The salience network dynamics in perceptual decision-making

Publication date: 1 July 2016
Source:NeuroImage, Volume 134
Author(s): Ganesh B. Chand, Mukesh Dhamala
Recent neuroimaging studies have demonstrated that the network consisting of the right anterior insula (rAI), left anterior insula (lAI) and dorsal anterior cingulate cortex (dACC) is activated in sensory stimulus-guided goal-directed behaviors. This network is often known as the salience network (SN). When and how a sensory signal enters and organizes within SN before reaching the central executive network including the prefrontal cortices is still a mystery. Previous electrophysiological studies focused on individual nodes of SN, either on dACC or rAI, have reports of conflicting findings of the earliest cortical activity within the network. Functional magnetic resonance imaging (fMRI) studies are not able to answer these questions in the time-scales of human sensory perception and decision-making. Here, using clear and noisy face-house image categorization tasks and human scalp electroencephalography (EEG) recordings combined with source reconstruction techniques, we study when and how oscillatory activity organizes SN during a perceptual decision. We uncovered that the beta-band (13–30Hz) oscillations bound SN, became most active around 100ms after the stimulus onset and the rAI acted as a main outflow hub within SN for easier decision making task. The SN activities (Granger causality measures) were negatively correlated with the decision response time (decision difficulty). These findings suggest that the SN activity precedes the executive control in mediating sensory and cognitive processing to arrive at visual perceptual decisions.



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Media multitasking is associated with distractibility and increased prefrontal activity in adolescents and young adults

Publication date: 1 July 2016
Source:NeuroImage, Volume 134
Author(s): M. Moisala, V. Salmela, L. Hietajärvi, E. Salo, S. Carlson, O. Salonen, K. Lonka, K. Hakkarainen, K. Salmela-Aro, K. Alho
The current generation of young people indulges in more media multitasking behavior (e.g., instant messaging while watching videos) in their everyday lives than older generations. Concerns have been raised about how this might affect their attentional functioning, as previous studies have indicated that extensive media multitasking in everyday life may be associated with decreased attentional control. In the current study, 149 adolescents and young adults (aged 13–24years) performed speech-listening and reading tasks that required maintaining attention in the presence of distractor stimuli in the other modality or dividing attention between two concurrent tasks. Brain activity during task performance was measured using functional magnetic resonance imaging (fMRI). We studied the relationship between self-reported daily media multitasking (MMT), task performance and brain activity during task performance. The results showed that in the presence of distractor stimuli, a higher MMT score was associated with worse performance and increased brain activity in right prefrontal regions. The level of performance during divided attention did not depend on MMT. This suggests that daily media multitasking is associated with behavioral distractibility and increased recruitment of brain areas involved in attentional and inhibitory control, and that media multitasking in everyday life does not translate to performance benefits in multitasking in laboratory settings.

Graphical abstract

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Neuronal interactions in areas of spatial attention reflect avoidance of disgust but orienting to danger

Publication date: 1 July 2016
Source:NeuroImage, Volume 134
Author(s): Ulrike Zimmer, Margit Höfler, Karl Koschutnig, Anja Ischebeck
For survival, it is necessary to attend quickly towards dangerous objects, but to turn away from something that is disgusting. We tested whether fear and disgust sounds direct spatial attention differently. Using fMRI, a sound cue (disgust, fear or neutral) was presented to the left or right ear. The cue was followed by a visual target (a small arrow) which was located on the same (valid) or opposite (invalid) side as the cue. Participants were required to decide whether the arrow pointed up- or downwards while ignoring the sound cue. Behaviorally, responses were faster for invalid compared to valid targets when cued by disgust, whereas the opposite pattern was observed for targets after fearful and neutral sound cues. During target presentation, activity in the visual cortex and IPL increased for targets invalidly cued with disgust, but for targets validly cued with fear which indicated a general modulation of activation due to attention. For the TPJ, an interaction in the opposite direction was observed, consistent with its role in detecting targets at unattended positions and in relocating attention. As a whole our results indicate that a disgusting sound directs spatial attention away from its location, in contrast to fearful and neutral sounds.



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Trails of meaning construction: Symbolic artifacts engage the social brain

Publication date: 1 July 2016
Source:NeuroImage, Volume 134
Author(s): Kristian Tylén, Johanne Stege Philipsen, Andreas Roepstorff, Riccardo Fusaroli
Symbolic artifacts present a challenge to theories of neurocognitive processing due to their hybrid nature: they are at the same time physical objects and vehicles of intangible social meanings. While their physical properties can be read of their perceptual appearance, the meaning of symbolic artifacts depends on the perceiver's interpretative attitude and embeddedness in cultural practices. In this study, participants built models of LEGO bricks to illustrate their understanding of abstract concepts. They were then scanned with fMRI while presented to photographs of their own and others' models. When participants attended to the meaning of the models in contrast to their bare physical properties, we observed activations in mPFC and TPJ, areas often associated with social cognition, and IFG, possibly related to semantics. When contrasting own and others' models, we also found activations in precuneus, an area associated with autobiographical memory and agency, while looking at one's own collective models yielded interaction effects in rostral ACC, right IFG and left Insula. Interestingly, variability in the insula was predicted by individual differences in participants' feeling of relatedness to their fellow group members during LEGO construction activity. Our findings support a view of symbolic artifacts as neuro-cognitive trails of human social interactions.



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Alpha power indexes task-related networks on large and small scales: A multimodal ECoG study in humans and a non-human primate

Publication date: 1 July 2016
Source:NeuroImage, Volume 134
Author(s): A. de Pesters, W.G. Coon, P. Brunner, A. Gunduz, A.L. Ritaccio, N.M. Brunet, P. de Weerd, M.J. Roberts, R. Oostenveld, P. Fries, G. Schalk
Performing different tasks, such as generating motor movements or processing sensory input, requires the recruitment of specific networks of neuronal populations. Previous studies suggested that power variations in the alpha band (8–12Hz) may implement such recruitment of task-specific populations by increasing cortical excitability in task-related areas while inhibiting population-level cortical activity in task-unrelated areas (Klimesch et al., 2007; Jensen and Mazaheri, 2010). However, the precise temporal and spatial relationships between the modulatory function implemented by alpha oscillations and population-level cortical activity remained undefined. Furthermore, while several studies suggested that alpha power indexes task-related populations across large and spatially separated cortical areas, it was largely unclear whether alpha power also differentially indexes smaller networks of task-related neuronal populations. Here we addressed these questions by investigating the temporal and spatial relationships of electrocorticographic (ECoG) power modulations in the alpha band and in the broadband gamma range (70–170Hz, indexing population-level activity) during auditory and motor tasks in five human subjects and one macaque monkey. In line with previous research, our results confirm that broadband gamma power accurately tracks task-related behavior and that alpha power decreases in task-related areas. More importantly, they demonstrate that alpha power suppression lags population-level activity in auditory areas during the auditory task, but precedes it in motor areas during the motor task. This suppression of alpha power in task-related areas was accompanied by an increase in areas not related to the task. In addition, we show for the first time that these differential modulations of alpha power could be observed not only across widely distributed systems (e.g., motor vs. auditory system), but also within the auditory system. Specifically, alpha power was suppressed in the locations within the auditory system that most robustly responded to particular sound stimuli. Altogether, our results provide experimental evidence for a mechanism that preferentially recruits task-related neuronal populations by increasing cortical excitability in task-related cortical areas and decreasing cortical excitability in task-unrelated areas. This mechanism is implemented by variations in alpha power and is common to humans and the non-human primate under study. These results contribute to an increasingly refined understanding of the mechanisms underlying the selection of the specific neuronal populations required for task execution.



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Inhibitors of Histone Deacetylases Attenuate Noise-Induced Hearing Loss

Abstract

Loss of auditory sensory hair cells is the major pathological feature of noise-induced hearing loss (NIHL). Currently, no established clinical therapies for prevention or amelioration of NIHL are available. The absence of treatments is due to our lack of a comprehensive understanding of the molecular mechanisms underlying noise-induced damage. Our previous study indicates that epigenetic modification of histones alters hair cell survival. In this study, we investigated the effect of noise exposure on histone H3 lysine 9 acetylation (H3K9ac) in the inner ear of adult CBA/J mice and determined if inhibition of histone deacetylases by systemic administration of suberoylanilide hydroxamic acid (SAHA) could attenuate NIHL. Our results showed that H3K9ac was decreased in the nuclei of outer hair cells (OHCs) and marginal cells of the stria vascularis in the basal region after exposure to a traumatic noise paradigm known to induce permanent threshold shifts (PTS). Consistent with these results, levels of histone deacetylases 1, 2, and 3 (HDAC1, HDAC2 and HDAC3) were increased predominately in the nuclei of cochlear cells. Silencing of HDAC1, HDAC2, or HDAC3 with siRNA reduced the expression of the target HDAC in OHCs, but did not attenuate noise-induced PTS, whereas treatment with the pan-HDAC inhibitor SAHA, also named vorinostat, reduced OHC loss, and attenuated PTS. These findings suggest that histone acetylation is involved in the pathogenesis of noise-induced OHC death and hearing loss. Pharmacological targeting of histone deacetylases may afford a strategy for protection against NIHL.

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Clinical Trial Evaluating the Risk of Thromboembolic Events During Dental Extractions

Abstract

Purpose

Discontinuation of anti-platelet therapy increases the risk of thrombotic complications whereas its continuation is believed to increase the risk of prolonged post-extraction bleeding. We therefore, performed this study to evaluate the risk of significant bleeding following dental extractions and also to assess the necessity of discontinuing anti-platelet therapy.

Patients and methods

Three hundred patients requiring dental extraction were included in the study in which 200 patients were on anti-platelet therapy. Patients were divided into three groups of 100 patients each. Group 1 consisted of patients continuing their anti-platelet therapy, Group 2 consisted of patients whose anti-platelet therapy was interrupted and Group 3 comprised of healthy patients not on anti-platelet therapy. Preoperative bleeding and clotting time were determined for all patients. The procedure involved single or multiple teeth (>3 teeth) extractions under local anesthesia with a vasoconstrictor. Pressure pack was given in all cases as in routine dental extractions and bleeding was checked after 15, 30 min, 1, 24, 48 h and 1 week. Immediate post-extraction bleeding was considered to be prolonged if it continued beyond 30 min in spite of the pressure pack. Late and very late bleeding was considered to be clinically significant if it extended beyond 12 and 24 h respectively.

Results

The mean bleeding time in Groups 1, 2, and 3 were 1 min and 32 s, 1 min and 25 s, and 1 min and 27 s, respectively. Prolonged immediate post-extraction bleeding (bleeding after 30 min) was present among 9 patients in Group 1 (9 %) and 15 patients in Group 2 (15 %) whereas it was not seen in any patient of Group 3. Bleeding after 1 h was present in 9 patients of Group 2 (9 %) and was controlled with gelatin sponge within half an hour thereafter. None of the patients in any group reported with bleeding after 24, 48 h and 1 week.

Conclusion

Dental extractions can be safely carried out in patients on anti-platelet therapy without the risk of significant post-extraction bleeding thus averting the risk of thromboembolic events that might take place on temporary discontinuation of antiplatelet therapy.

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Ocular Injuries in Patients of Zygomatico-Complex (ZMC) Fractures

Abstract

Purpose

Mid face injuries commonly destroy the integrity of the orbital skeleton, and are frequently complicated by injury to the eye, ranging between 2.7 and 90.6 % as reported in literature. The eye injuries range from simple subconjunctival haemorrhage to globe rupture. The paper aims to study the types of ocular injuries in patients with ZMC fractures.

Patients and Methods

A study of 67 patients, who had sustained facial trauma sufficient to lead to a facial bone fracture, was undertaken in the department of Oral and Maxillofacial Surgery, Govt Dental College, Srinagar from 2008 to 2014 and the patients received a comprehensive examination by an ophthalmologist within 1 week of injury. All the patients sustaining confirmed ZMC fracture were examined by an ophthalmologist for any associated ocular injury. A thorough ophthalmologic examination included assessment of visual acuity, pupillary reactivity, anterior and posterior segment examination and extraocular motility. The variables reviewed included patient's gender, mechanism of injury, visual acuity, pupillary reactivity, extra ocular motility, presence or absence of diplopia, ocular and orbital findings, and intraorbital hypoesthesia.

Results

The most common etiology of trauma was RTA (64.1 %), followed by falls (14.9 %) in our study. In our study 83.5 % of the patients were males. Minor ocular injuries such as subconjunctival haemorrhage and corneal injury accounted for most of the cases. Subconjunctival haemorrhage was the most common injury, present in 86.5 % of the cases. Hyphema was present 13.4 %, vitreous haemorrhage 2.98 %, retinal haemorrhage 1.49 %, corneal abrasion 4.47 %, mydriasis 1.49 %, choroidal rupture 5.97 %, retinal detachment 2.98 %, decreased visual activity 13.4 %, retinal tear and angle recession was present 7.46 % times.

Conclusion

ZMC fractures are associated with higher incidence of ocular injuries. The incidence of traumatic optic neuropathy and other ocular injuries warrants a prompt ophthalmologic examination of all patients with ZMC fractures as quickly as possible to prevent morbidity.

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Comparison of Ropivacaine 0.75% and Lignocaine 2% with 1:200000 Adrenaline in Dental Extractions: Single Blind Clinical Trial

Abstract

Introduction

The aim of this study was to evaluate the efficacy, safety and clinical acceptability of the local anaesthetic agent ropivacaine 0.75 % in comparison with lignocaine 2 % with adrenaline 1:200,000 in minor oral surgical procedures.

Methods

Forty-seven patients, who required bilateral extractions in a single arch, were included in this study. One hundred and sixty-six extractions were performed and all the patients were administered nerve blocks/infiltration. Pre and postoperative pulse, blood pressure, random blood sugar, electrocardiogram and partial oxygen pressure were recorded at specified time intervals. Pain score by visual analogue scale, onset of action and depth of anesthesia were also observed. Duration of anaesthesia was assessed by feeling of numbness and first sign of pain.

Results

Statistical analysis revealed insignificant difference between both the groups in terms of pulse, blood pressure, random blood sugar, and partial oxygen pressure. The depth of anesthesia was evaluated by pain, comfort during the procedure with visual analog scale and showed no significant difference between the two groups. The onset of action for maxillary infiltration was 33.29 ± 9.2 (ropivacaine), 32.12 ± 6.8 s (2 % lignocaine with adrenaline 1:200,000) and for pterygomandibular nerve block was 181.0 ± 87.5 (ropivacaine), 32.12 ± 6.8 s (2 % lignocaine with adrenaline 1:200,000). Duration of anesthesia when compared was 411.7 ± 66.11 min (ropivacaine) and 107.87 ± 16.54 (2 % lignocaine with adrenaline 1:200,000). On maxillary buccal vestibule infiltration it was also observed that in ropivacaine group there was no requirement of palatal infiltration suggestive of good diffusion property.

Conclusion

Ropivacaine is a safe, clinically acceptable long acting local anaesthetic agent with added advantage of effective diffusion property.

Ethical Committee Approval Number

SDC/MISC/2013/239.

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Conversion of Aneurysmal Bone Cyst into Fibrous Dysplasia: A Rare Pediatric Case Report

Abstract

Aneurysmal bone cyst (ABC) is an uncommon, non-neoplastic, expansive and erosive bone lesion. Considered as a pseudocyst due the lack of epithelial lining, the presence of giant cells and similarity to other lesions can make preoperative diagnosis difficult; biopsy findings must be co-related to complete clinical and radiological assessment. ABC's controversial etiopathogenesis and variable clinicopathological presentations have been widely described, but to date, there are just a few reports in literature describing the development of fibrous dysplasia (FD) from an ABC, and even less cases occurring in the jaws. We describe the case of an ABC in an 8 year-old male patient, affecting the body of the mandible, which showed accelerated growth associated to thinning of the buccal, lingual and lower cortical plates. The treatment consisted of repetitive surgical resection, curettage of the lesion and mandibular reinforcement with osteosynthesis reconstruction plates. A 16-month follow-up showed self-limitation of the overgrowth. The final histopathological and radiological analysis confirmed the FD diagnosis.

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Dont Know Cant Do Wont Change: Barriers to Moving Knowledge to Action in Managing the Carious Lesion

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A Randomized Clinical Trial Evaluating rh-FGF-2/{beta}-TCP in Periodontal Defects

Biological mediators have been used to enhance periodontal regeneration. The aim of this prospective randomized controlled study was to evaluate the safety and effectiveness of 3 doses of fibroblast growth factor 2 (FGF-2) when combined with a β-tricalcium phosphate (β-TCP) scaffold carrier placed in vertical infrabony periodontal defects in adult patients. In this double-blinded, dose-verification, externally monitored clinical study, 88 patients who required surgical intervention to treat a qualifying infrabony periodontal defect were randomized to 1 of 4 treatment groups—β-TCP alone (control) and 0.1% recombinant human FGF-2 (rh-FGF-2), 0.3% rh-FGF-2, and 0.4% rh-FGF-2 with β-TCP—following scaling and root planing of the tooth prior to a surgical appointment. Flap surgery was performed with EDTA conditioning of the root prior to device implantation. There were no statistically significant differences in patient demographics and baseline characteristics among the 4 treatment groups. When a composite outcome of gain in clinical attachment of 1.5 mm was used with a linear bone growth of 2.5 mm, a dose response pattern detected a plateau in the 0.3% and 0.4% rh-FGF-2/β-TCP groups with significant improvements over control and 0.1% rh-FGF-2/β-TCP groups. The success rate at 6 mo was 71% in the 2 higher-concentration groups, as compared with 45% in the control and lowest treatment groups. Percentage bone fill in the 2 higher-concentration groups was 75% and 71%, compared with 63% and 61% in the control and lowest treatment group. No increases in specific antibody to rh-FGF-2 were detected, and no serious adverse events related to the products were reported. The results from this multicenter trial demonstrated that the treatment of infrabony vertical periodontal defects can be enhanced with the addition of rh-FGF-2/β-TCP (ClinicalTrials.gov NCT01728844).

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Surface Engineering of Nanostructured Titanium Implants with Bioactive Ions

Surface nanofeatures and bioactive ion chemical modification are centrally important in current titanium (Ti) oral implants for enhancing osseointegration. However, it is unclear whether the addition of bioactive ions definitively enhances the osteogenic capacity of a nanostructured Ti implant. We systematically investigated the osteogenesis process of human multipotent adipose stem cells triggered by bioactive ions in the nanostructured Ti implant surface. Here, we report that bioactive ion surface modification (calcium [Ca] or strontium [Sr]) and resultant ion release significantly increase osteogenic activity of the nanofeatured Ti surface. We for the first time demonstrate that ion modification actively induces focal adhesion development and expression of critical adhesion–related genes (vinculin, talin, and RHOA) of human multipotent adipose stem cells, resulting in enhanced osteogenic differentiation on the nanofeatured Ti surface. It is also suggested that fibronectin adsorption may have only a weak effect on early cellular events of mesenchymal stem cells (MSCs) at least in the case of the nanostructured Ti implant surface incorporating Sr. Moreover, results indicate that Sr overrides the effect of Ca and other important surface factors (i.e., surface area and wettability) in the osteogenesis function of various MSCs (derived from human adipose, bone marrow, and murine bone marrow). In addition, surface engineering of nanostructured Ti implants using Sr ions is expected to exert additional beneficial effects on implant bone healing through the proper balancing of the allocation of MSCs between adipogenesis and osteogenesis. This work provides insight into the future surface design of Ti dental implants using surface bioactive ion chemistry and nanotopography.

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Pragmatic RCT on the Efficacy of Proximal Caries Infiltration

Proximal caries infiltration has been shown to be efficacious in hampering caries lesion progression when performed by dentists working in a university setting. The aim of this randomized split-mouth, placebo-controlled clinical trial was to assess the efficacy of resin infiltration of proximal caries lesions being performed by several dentists in private practices, in combination with individualized oral hygiene plus noninvasive measures compared with these alone. In this study, 87 children and young adults (with 238 pairs of proximal caries lesions radiographically extending into the inner half of the enamel [E2] or the outer third of the dentin [D1]) were randomly allocated to either 1 of 2 treatments. Test lesions were infiltrated, and a mock treatment was performed in control lesions by 5 German private practitioners. All patients received instructions for a noncariogenic diet, flossing and fluoridation, and individualized noninvasive interventions. The primary outcome was radiographic lesion progression (pairwise comparison) evaluated independently by 2 evaluators who were blinded to treatment allocation. After approximately 10 mo (mean ± SD 307 ± 43 d), 92 of 148 lesion pairs in 24 of 38 treated patients who were at high caries risk could be re-evaluated clinically as well as radiographically using individualized bitewing holders, as at baseline; 186 of 204 lesion pairs in 70 of 77 patients (35 of 38 high-risk patients) could be evaluated after 18 mo (mean 542 ± 110 d). No unwanted effects were observed. After 10 mo, progression was recorded in 2 of 92 test lesions (2%) and in 22 of 92 control lesions (24%) (P = 0.001, McNemar/Obuchowski test; relative risk reduction, 91; 95% confidence interval, 62%–98%). After 18 mo, lesion progression was recorded in all included patients in 10 of 186 test lesions (5%) and in 58 of 186 control lesions (31%) (P < 0.001; relative risk reduction, 83; 95% confidence interval, 67%–91%). Thus, resin infiltration seems to be more efficacious in reducing lesion progression compared with individualized noninvasive measures alone over a period of 18 mo when performed in a private practice setting by various practitioners (German Clinical Trials Register / Deutsches Register Klinischer Studien DRKS00009963).

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Laboratory Studies of Nonlinear Optical Signals for Caries Detection

Multiphoton confocal microscopy and nonlinear spectroscopy are used to investigate the caries process in dentin. Although dentin is a major calcified tissue of the teeth, its organic phase comprises type I collagen fibers. Caries drive dentin demineralization and collagen denaturation. Multiphoton microscopy is a powerful imaging technique: the biological materials are transparent to infrared frequencies and can be excited to penetration depths inaccessible to 1-photon confocal microscopy. The laser excitation greatly reduces photodamage to the sole focal region, and the signal-to-noise ratio is improved significantly. The method has been used to follow pathologic processes involving collagen fibrosis or collagen destruction based on their 2-photon excited fluorescence (2PEF) emission and second harmonic generation (SHG). Combining multiphoton imaging with nonlinear spectroscopy, we demonstrate that both 2PEF and SHG intensity of human dentin are strongly modified during the tooth caries process, and we show that the ratio between SHG and 2PEF signals is a reliable parameter to follow dental caries. The ratio of the SHG/2PEF signals measured by nonlinear optical spectroscopy provides valuable information on the caries process, specifically on the degradation of the organic matrix of dentin. The goal is to bring these nonlinear optical signals to clinical application for caries diagnosis.

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Dental Surface Texture Characterization Based on Erosive Tooth Wear Processes

The differential diagnosis of dental wear lesions affects their clinical management. We hypothesized that surface texture parameters can differentiate simulated erosion, abrasion, and erosion-abrasion lesions on human enamel and dentin. This in vitro study comprised 2 parts (both factorial 4 x 2), with 4 lesion types (erosion, abrasion, erosion-abrasion, and sound [no lesion; control]) and 2 substrates (enamel and dentin). Flattened/polished dental specimens were used in part 1, whereas natural dental surfaces were used in part 2. Testing surfaces were evaluated in blind conditions, using average surface roughness (Sa) and the following scale-sensitive fractal analysis parameters: area-scale fractal complexity (Asfc), exact proportion length-scale anisotropy of relief (eplsar), scale of maximum complexity (Smc), and textural fill volume (Tfv). Two-way analyses of variance, followed by Fisher's protected least significant difference tests (α = 0.05), were used to evaluate the effects of lesion and substrate. Classification trees were constructed to verify the strength of potential associations of the tested parameters. In part 1, Asfc, Sa, and Tfv were able to differentiate erosion and erosion-abrasion lesions from the sound (no lesion) control in both substrates; only Asfc differentiated erosion and erosion-abrasion enamel lesions (all P < 0.05). The best association of parameters correctly classified up to 84% and 94% of the lesions on enamel and dentin, respectively. In part 2, only Asfc differentiated erosion and erosion-abrasion lesions from the sound (no lesion) control in both substrates, whereas eplsar was able to differentiate erosion from erosion-abrasion (all P < 0.05). The association of parameters correctly classified up to 81% and 91% of the lesions in enamel and dentin, respectively. Asfc, Sa, and Tfv were able to differentiate erosion and erosion-abrasion lesions, despite their complicated surface textures. The association of parameters improved the differentiation of lesions for both enamel and dentin in polished or natural surfaces.

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Evidence for Bicarbonate Secretion by Ameloblasts in a Novel Cellular Model

Formation and growth of hydroxyapatite crystals during amelogenesis generate a large number of protons that must be neutralized, presumably by HCO₃^– ions transported from ameloblasts into the developing enamel matrix. Ameloblasts express a number of transporters and channels known to be involved in HCO₃^– transport in other epithelia. However, to date, there is no functional evidence for HCO₃^– transport in these cells. To address questions related to HCO₃^– export from ameloblasts, we have developed a polarized 2-dimensional culture system for HAT-7 cells, a rat cell line of ameloblast origin. HAT-7 cells were seeded onto Transwell permeable filters. Transepithelial resistance was measured as a function of time, and the expression of transporters and tight junction proteins was investigated by conventional and quantitative reverse transcription polymerase chain reaction. Intracellular pH regulation and HCO₃^– transport were assessed by microfluorometry. HAT-7 cells formed epithelial layers with measureable transepithelial resistance on Transwell permeable supports and expressed claudin-1, claudin-4, and claudin-8—key proteins for tight junction formation. Transport proteins previously described in maturation ameloblasts were also present in HAT-7 cells. Microfluorometry showed that the HAT-7 cells were polarized with a high apical membrane CO₂ permeability and vigorous basolateral HCO₃^– uptake, which was sensitive to Na⁺ withdrawal, to the carbonic anhydrase inhibitor acetazolamide and to H₂DIDS inhibition. Measurements of transepithelial HCO₃^– transport showed a marked increase in response to Ca²⁺- and cAMP-mobilizing stimuli. Collectively, 2-dimensional HAT-7 cell cultures on permeable supports 1) form tight junctions, 2) express typical tight junction proteins and electrolyte transporters, 3) are functionally polarized, and 4) can accumulate HCO₃^– ions from the basolateral side and secrete them at the apical membrane. These studies provide evidence for a regulated, vectorial, basolateral-to-apical bicarbonate transport in polarized HAT-7 cells. We therefore propose that the HAT-7 cell line is a useful functional model for studying electrolyte transport by ameloblasts.

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Effective Expansion: Balance between Shrinkage and Hygroscopic Expansion

The purpose of this study was to investigate the relationship between hygroscopic expansion and polymerization shrinkage for compensation of polymerization shrinkage stresses in a restored tooth. One resin-modified glass-ionomer (RMGI) (Ketac Nano, 3M ESPE), 2 compomers (Dyract, Dentsply; Compoglass, Ivoclar), and a universal resin-based composite (Esthet•X HD, Dentsply) were tested. Volumetric change after polymerization ("total shrinkage") and during 4 wk of water storage at 37°C was measured using an optical method (n = 10). Post-gel shrinkage was measured during polymerization using a strain gauge method (n = 10). Extracted human molars with large mesio-occluso-distal slot preparations were restored with the tested restorative materials. Tooth surfaces at baseline (preparation), after restoration, and during 4 wk of 37°C water storage were scanned with an optical scanner to determine cuspal flexure (n = 8). Occlusal interface integrity was measured using dye penetration. Data were analyzed using analysis of variance and post hoc tests (significance level 0.05). All tested materials shrunk after polymerization. RMGI had the highest total shrinkage (4.65%) but lowest post-gel shrinkage (0.35%). Shrinkage values dropped significantly during storage in water but had not completely compensated polymerization shrinkage after 4 wk. All restored teeth initially exhibited inward (negative) cuspal flexure due to polymerization shrinkage. Cuspal flexure with the RMGI restoration was significantly less (–6.4 µm) than with the other materials (–12.1 to –14.1 µm). After 1 d, cuspal flexure reversed to +5.0 µm cuspal expansion with the RMGI and increased to +9.3 µm at 4 wk. After 4 wk, hygroscopic expansion compensated cuspal flexure in a compomer (Compoglass) and reduced flexure with Dyract and resin-based composite. Marginal integrity (93.7% intact restoration wall) was best for the Compoglass restorations and lowest (73.1%) for the RMGI restorations. Hygroscopic expansion was more effective in compensating shrinkage stress than would be assumed based on total shrinkage, because only post-gel shrinkage needed compensation. Effective expansion is therefore hygroscopic expansion minus post-gel shrinkage.

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Clinical Trial Evaluating the Risk of Thromboembolic Events During Dental Extractions

Abstract

Purpose

Discontinuation of anti-platelet therapy increases the risk of thrombotic complications whereas its continuation is believed to increase the risk of prolonged post-extraction bleeding. We therefore, performed this study to evaluate the risk of significant bleeding following dental extractions and also to assess the necessity of discontinuing anti-platelet therapy.

Patients and methods

Three hundred patients requiring dental extraction were included in the study in which 200 patients were on anti-platelet therapy. Patients were divided into three groups of 100 patients each. Group 1 consisted of patients continuing their anti-platelet therapy, Group 2 consisted of patients whose anti-platelet therapy was interrupted and Group 3 comprised of healthy patients not on anti-platelet therapy. Preoperative bleeding and clotting time were determined for all patients. The procedure involved single or multiple teeth (>3 teeth) extractions under local anesthesia with a vasoconstrictor. Pressure pack was given in all cases as in routine dental extractions and bleeding was checked after 15, 30 min, 1, 24, 48 h and 1 week. Immediate post-extraction bleeding was considered to be prolonged if it continued beyond 30 min in spite of the pressure pack. Late and very late bleeding was considered to be clinically significant if it extended beyond 12 and 24 h respectively.

Results

The mean bleeding time in Groups 1, 2, and 3 were 1 min and 32 s, 1 min and 25 s, and 1 min and 27 s, respectively. Prolonged immediate post-extraction bleeding (bleeding after 30 min) was present among 9 patients in Group 1 (9 %) and 15 patients in Group 2 (15 %) whereas it was not seen in any patient of Group 3. Bleeding after 1 h was present in 9 patients of Group 2 (9 %) and was controlled with gelatin sponge within half an hour thereafter. None of the patients in any group reported with bleeding after 24, 48 h and 1 week.

Conclusion

Dental extractions can be safely carried out in patients on anti-platelet therapy without the risk of significant post-extraction bleeding thus averting the risk of thromboembolic events that might take place on temporary discontinuation of antiplatelet therapy.

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Ocular Injuries in Patients of Zygomatico-Complex (ZMC) Fractures

Abstract

Purpose

Mid face injuries commonly destroy the integrity of the orbital skeleton, and are frequently complicated by injury to the eye, ranging between 2.7 and 90.6 % as reported in literature. The eye injuries range from simple subconjunctival haemorrhage to globe rupture. The paper aims to study the types of ocular injuries in patients with ZMC fractures.

Patients and Methods

A study of 67 patients, who had sustained facial trauma sufficient to lead to a facial bone fracture, was undertaken in the department of Oral and Maxillofacial Surgery, Govt Dental College, Srinagar from 2008 to 2014 and the patients received a comprehensive examination by an ophthalmologist within 1 week of injury. All the patients sustaining confirmed ZMC fracture were examined by an ophthalmologist for any associated ocular injury. A thorough ophthalmologic examination included assessment of visual acuity, pupillary reactivity, anterior and posterior segment examination and extraocular motility. The variables reviewed included patient's gender, mechanism of injury, visual acuity, pupillary reactivity, extra ocular motility, presence or absence of diplopia, ocular and orbital findings, and intraorbital hypoesthesia.

Results

The most common etiology of trauma was RTA (64.1 %), followed by falls (14.9 %) in our study. In our study 83.5 % of the patients were males. Minor ocular injuries such as subconjunctival haemorrhage and corneal injury accounted for most of the cases. Subconjunctival haemorrhage was the most common injury, present in 86.5 % of the cases. Hyphema was present 13.4 %, vitreous haemorrhage 2.98 %, retinal haemorrhage 1.49 %, corneal abrasion 4.47 %, mydriasis 1.49 %, choroidal rupture 5.97 %, retinal detachment 2.98 %, decreased visual activity 13.4 %, retinal tear and angle recession was present 7.46 % times.

Conclusion

ZMC fractures are associated with higher incidence of ocular injuries. The incidence of traumatic optic neuropathy and other ocular injuries warrants a prompt ophthalmologic examination of all patients with ZMC fractures as quickly as possible to prevent morbidity.

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Comparison of Ropivacaine 0.75% and Lignocaine 2% with 1:200000 Adrenaline in Dental Extractions: Single Blind Clinical Trial

Abstract

Introduction

The aim of this study was to evaluate the efficacy, safety and clinical acceptability of the local anaesthetic agent ropivacaine 0.75 % in comparison with lignocaine 2 % with adrenaline 1:200,000 in minor oral surgical procedures.

Methods

Forty-seven patients, who required bilateral extractions in a single arch, were included in this study. One hundred and sixty-six extractions were performed and all the patients were administered nerve blocks/infiltration. Pre and postoperative pulse, blood pressure, random blood sugar, electrocardiogram and partial oxygen pressure were recorded at specified time intervals. Pain score by visual analogue scale, onset of action and depth of anesthesia were also observed. Duration of anaesthesia was assessed by feeling of numbness and first sign of pain.

Results

Statistical analysis revealed insignificant difference between both the groups in terms of pulse, blood pressure, random blood sugar, and partial oxygen pressure. The depth of anesthesia was evaluated by pain, comfort during the procedure with visual analog scale and showed no significant difference between the two groups. The onset of action for maxillary infiltration was 33.29 ± 9.2 (ropivacaine), 32.12 ± 6.8 s (2 % lignocaine with adrenaline 1:200,000) and for pterygomandibular nerve block was 181.0 ± 87.5 (ropivacaine), 32.12 ± 6.8 s (2 % lignocaine with adrenaline 1:200,000). Duration of anesthesia when compared was 411.7 ± 66.11 min (ropivacaine) and 107.87 ± 16.54 (2 % lignocaine with adrenaline 1:200,000). On maxillary buccal vestibule infiltration it was also observed that in ropivacaine group there was no requirement of palatal infiltration suggestive of good diffusion property.

Conclusion

Ropivacaine is a safe, clinically acceptable long acting local anaesthetic agent with added advantage of effective diffusion property.

Ethical Committee Approval Number

SDC/MISC/2013/239.

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Conversion of Aneurysmal Bone Cyst into Fibrous Dysplasia: A Rare Pediatric Case Report

Abstract

Aneurysmal bone cyst (ABC) is an uncommon, non-neoplastic, expansive and erosive bone lesion. Considered as a pseudocyst due the lack of epithelial lining, the presence of giant cells and similarity to other lesions can make preoperative diagnosis difficult; biopsy findings must be co-related to complete clinical and radiological assessment. ABC's controversial etiopathogenesis and variable clinicopathological presentations have been widely described, but to date, there are just a few reports in literature describing the development of fibrous dysplasia (FD) from an ABC, and even less cases occurring in the jaws. We describe the case of an ABC in an 8 year-old male patient, affecting the body of the mandible, which showed accelerated growth associated to thinning of the buccal, lingual and lower cortical plates. The treatment consisted of repetitive surgical resection, curettage of the lesion and mandibular reinforcement with osteosynthesis reconstruction plates. A 16-month follow-up showed self-limitation of the overgrowth. The final histopathological and radiological analysis confirmed the FD diagnosis.

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Dont Know Cant Do Wont Change: Barriers to Moving Knowledge to Action in Managing the Carious Lesion

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A Randomized Clinical Trial Evaluating rh-FGF-2/{beta}-TCP in Periodontal Defects

Biological mediators have been used to enhance periodontal regeneration. The aim of this prospective randomized controlled study was to evaluate the safety and effectiveness of 3 doses of fibroblast growth factor 2 (FGF-2) when combined with a β-tricalcium phosphate (β-TCP) scaffold carrier placed in vertical infrabony periodontal defects in adult patients. In this double-blinded, dose-verification, externally monitored clinical study, 88 patients who required surgical intervention to treat a qualifying infrabony periodontal defect were randomized to 1 of 4 treatment groups—β-TCP alone (control) and 0.1% recombinant human FGF-2 (rh-FGF-2), 0.3% rh-FGF-2, and 0.4% rh-FGF-2 with β-TCP—following scaling and root planing of the tooth prior to a surgical appointment. Flap surgery was performed with EDTA conditioning of the root prior to device implantation. There were no statistically significant differences in patient demographics and baseline characteristics among the 4 treatment groups. When a composite outcome of gain in clinical attachment of 1.5 mm was used with a linear bone growth of 2.5 mm, a dose response pattern detected a plateau in the 0.3% and 0.4% rh-FGF-2/β-TCP groups with significant improvements over control and 0.1% rh-FGF-2/β-TCP groups. The success rate at 6 mo was 71% in the 2 higher-concentration groups, as compared with 45% in the control and lowest treatment groups. Percentage bone fill in the 2 higher-concentration groups was 75% and 71%, compared with 63% and 61% in the control and lowest treatment group. No increases in specific antibody to rh-FGF-2 were detected, and no serious adverse events related to the products were reported. The results from this multicenter trial demonstrated that the treatment of infrabony vertical periodontal defects can be enhanced with the addition of rh-FGF-2/β-TCP (ClinicalTrials.gov NCT01728844).

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Surface Engineering of Nanostructured Titanium Implants with Bioactive Ions

Surface nanofeatures and bioactive ion chemical modification are centrally important in current titanium (Ti) oral implants for enhancing osseointegration. However, it is unclear whether the addition of bioactive ions definitively enhances the osteogenic capacity of a nanostructured Ti implant. We systematically investigated the osteogenesis process of human multipotent adipose stem cells triggered by bioactive ions in the nanostructured Ti implant surface. Here, we report that bioactive ion surface modification (calcium [Ca] or strontium [Sr]) and resultant ion release significantly increase osteogenic activity of the nanofeatured Ti surface. We for the first time demonstrate that ion modification actively induces focal adhesion development and expression of critical adhesion–related genes (vinculin, talin, and RHOA) of human multipotent adipose stem cells, resulting in enhanced osteogenic differentiation on the nanofeatured Ti surface. It is also suggested that fibronectin adsorption may have only a weak effect on early cellular events of mesenchymal stem cells (MSCs) at least in the case of the nanostructured Ti implant surface incorporating Sr. Moreover, results indicate that Sr overrides the effect of Ca and other important surface factors (i.e., surface area and wettability) in the osteogenesis function of various MSCs (derived from human adipose, bone marrow, and murine bone marrow). In addition, surface engineering of nanostructured Ti implants using Sr ions is expected to exert additional beneficial effects on implant bone healing through the proper balancing of the allocation of MSCs between adipogenesis and osteogenesis. This work provides insight into the future surface design of Ti dental implants using surface bioactive ion chemistry and nanotopography.

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Pragmatic RCT on the Efficacy of Proximal Caries Infiltration

Proximal caries infiltration has been shown to be efficacious in hampering caries lesion progression when performed by dentists working in a university setting. The aim of this randomized split-mouth, placebo-controlled clinical trial was to assess the efficacy of resin infiltration of proximal caries lesions being performed by several dentists in private practices, in combination with individualized oral hygiene plus noninvasive measures compared with these alone. In this study, 87 children and young adults (with 238 pairs of proximal caries lesions radiographically extending into the inner half of the enamel [E2] or the outer third of the dentin [D1]) were randomly allocated to either 1 of 2 treatments. Test lesions were infiltrated, and a mock treatment was performed in control lesions by 5 German private practitioners. All patients received instructions for a noncariogenic diet, flossing and fluoridation, and individualized noninvasive interventions. The primary outcome was radiographic lesion progression (pairwise comparison) evaluated independently by 2 evaluators who were blinded to treatment allocation. After approximately 10 mo (mean ± SD 307 ± 43 d), 92 of 148 lesion pairs in 24 of 38 treated patients who were at high caries risk could be re-evaluated clinically as well as radiographically using individualized bitewing holders, as at baseline; 186 of 204 lesion pairs in 70 of 77 patients (35 of 38 high-risk patients) could be evaluated after 18 mo (mean 542 ± 110 d). No unwanted effects were observed. After 10 mo, progression was recorded in 2 of 92 test lesions (2%) and in 22 of 92 control lesions (24%) (P = 0.001, McNemar/Obuchowski test; relative risk reduction, 91; 95% confidence interval, 62%–98%). After 18 mo, lesion progression was recorded in all included patients in 10 of 186 test lesions (5%) and in 58 of 186 control lesions (31%) (P < 0.001; relative risk reduction, 83; 95% confidence interval, 67%–91%). Thus, resin infiltration seems to be more efficacious in reducing lesion progression compared with individualized noninvasive measures alone over a period of 18 mo when performed in a private practice setting by various practitioners (German Clinical Trials Register / Deutsches Register Klinischer Studien DRKS00009963).

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Laboratory Studies of Nonlinear Optical Signals for Caries Detection

Multiphoton confocal microscopy and nonlinear spectroscopy are used to investigate the caries process in dentin. Although dentin is a major calcified tissue of the teeth, its organic phase comprises type I collagen fibers. Caries drive dentin demineralization and collagen denaturation. Multiphoton microscopy is a powerful imaging technique: the biological materials are transparent to infrared frequencies and can be excited to penetration depths inaccessible to 1-photon confocal microscopy. The laser excitation greatly reduces photodamage to the sole focal region, and the signal-to-noise ratio is improved significantly. The method has been used to follow pathologic processes involving collagen fibrosis or collagen destruction based on their 2-photon excited fluorescence (2PEF) emission and second harmonic generation (SHG). Combining multiphoton imaging with nonlinear spectroscopy, we demonstrate that both 2PEF and SHG intensity of human dentin are strongly modified during the tooth caries process, and we show that the ratio between SHG and 2PEF signals is a reliable parameter to follow dental caries. The ratio of the SHG/2PEF signals measured by nonlinear optical spectroscopy provides valuable information on the caries process, specifically on the degradation of the organic matrix of dentin. The goal is to bring these nonlinear optical signals to clinical application for caries diagnosis.

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Dental Surface Texture Characterization Based on Erosive Tooth Wear Processes

The differential diagnosis of dental wear lesions affects their clinical management. We hypothesized that surface texture parameters can differentiate simulated erosion, abrasion, and erosion-abrasion lesions on human enamel and dentin. This in vitro study comprised 2 parts (both factorial 4 x 2), with 4 lesion types (erosion, abrasion, erosion-abrasion, and sound [no lesion; control]) and 2 substrates (enamel and dentin). Flattened/polished dental specimens were used in part 1, whereas natural dental surfaces were used in part 2. Testing surfaces were evaluated in blind conditions, using average surface roughness (Sa) and the following scale-sensitive fractal analysis parameters: area-scale fractal complexity (Asfc), exact proportion length-scale anisotropy of relief (eplsar), scale of maximum complexity (Smc), and textural fill volume (Tfv). Two-way analyses of variance, followed by Fisher's protected least significant difference tests (α = 0.05), were used to evaluate the effects of lesion and substrate. Classification trees were constructed to verify the strength of potential associations of the tested parameters. In part 1, Asfc, Sa, and Tfv were able to differentiate erosion and erosion-abrasion lesions from the sound (no lesion) control in both substrates; only Asfc differentiated erosion and erosion-abrasion enamel lesions (all P < 0.05). The best association of parameters correctly classified up to 84% and 94% of the lesions on enamel and dentin, respectively. In part 2, only Asfc differentiated erosion and erosion-abrasion lesions from the sound (no lesion) control in both substrates, whereas eplsar was able to differentiate erosion from erosion-abrasion (all P < 0.05). The association of parameters correctly classified up to 81% and 91% of the lesions in enamel and dentin, respectively. Asfc, Sa, and Tfv were able to differentiate erosion and erosion-abrasion lesions, despite their complicated surface textures. The association of parameters improved the differentiation of lesions for both enamel and dentin in polished or natural surfaces.

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Evidence for Bicarbonate Secretion by Ameloblasts in a Novel Cellular Model

Formation and growth of hydroxyapatite crystals during amelogenesis generate a large number of protons that must be neutralized, presumably by HCO₃^– ions transported from ameloblasts into the developing enamel matrix. Ameloblasts express a number of transporters and channels known to be involved in HCO₃^– transport in other epithelia. However, to date, there is no functional evidence for HCO₃^– transport in these cells. To address questions related to HCO₃^– export from ameloblasts, we have developed a polarized 2-dimensional culture system for HAT-7 cells, a rat cell line of ameloblast origin. HAT-7 cells were seeded onto Transwell permeable filters. Transepithelial resistance was measured as a function of time, and the expression of transporters and tight junction proteins was investigated by conventional and quantitative reverse transcription polymerase chain reaction. Intracellular pH regulation and HCO₃^– transport were assessed by microfluorometry. HAT-7 cells formed epithelial layers with measureable transepithelial resistance on Transwell permeable supports and expressed claudin-1, claudin-4, and claudin-8—key proteins for tight junction formation. Transport proteins previously described in maturation ameloblasts were also present in HAT-7 cells. Microfluorometry showed that the HAT-7 cells were polarized with a high apical membrane CO₂ permeability and vigorous basolateral HCO₃^– uptake, which was sensitive to Na⁺ withdrawal, to the carbonic anhydrase inhibitor acetazolamide and to H₂DIDS inhibition. Measurements of transepithelial HCO₃^– transport showed a marked increase in response to Ca²⁺- and cAMP-mobilizing stimuli. Collectively, 2-dimensional HAT-7 cell cultures on permeable supports 1) form tight junctions, 2) express typical tight junction proteins and electrolyte transporters, 3) are functionally polarized, and 4) can accumulate HCO₃^– ions from the basolateral side and secrete them at the apical membrane. These studies provide evidence for a regulated, vectorial, basolateral-to-apical bicarbonate transport in polarized HAT-7 cells. We therefore propose that the HAT-7 cell line is a useful functional model for studying electrolyte transport by ameloblasts.

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Effective Expansion: Balance between Shrinkage and Hygroscopic Expansion

The purpose of this study was to investigate the relationship between hygroscopic expansion and polymerization shrinkage for compensation of polymerization shrinkage stresses in a restored tooth. One resin-modified glass-ionomer (RMGI) (Ketac Nano, 3M ESPE), 2 compomers (Dyract, Dentsply; Compoglass, Ivoclar), and a universal resin-based composite (Esthet•X HD, Dentsply) were tested. Volumetric change after polymerization ("total shrinkage") and during 4 wk of water storage at 37°C was measured using an optical method (n = 10). Post-gel shrinkage was measured during polymerization using a strain gauge method (n = 10). Extracted human molars with large mesio-occluso-distal slot preparations were restored with the tested restorative materials. Tooth surfaces at baseline (preparation), after restoration, and during 4 wk of 37°C water storage were scanned with an optical scanner to determine cuspal flexure (n = 8). Occlusal interface integrity was measured using dye penetration. Data were analyzed using analysis of variance and post hoc tests (significance level 0.05). All tested materials shrunk after polymerization. RMGI had the highest total shrinkage (4.65%) but lowest post-gel shrinkage (0.35%). Shrinkage values dropped significantly during storage in water but had not completely compensated polymerization shrinkage after 4 wk. All restored teeth initially exhibited inward (negative) cuspal flexure due to polymerization shrinkage. Cuspal flexure with the RMGI restoration was significantly less (–6.4 µm) than with the other materials (–12.1 to –14.1 µm). After 1 d, cuspal flexure reversed to +5.0 µm cuspal expansion with the RMGI and increased to +9.3 µm at 4 wk. After 4 wk, hygroscopic expansion compensated cuspal flexure in a compomer (Compoglass) and reduced flexure with Dyract and resin-based composite. Marginal integrity (93.7% intact restoration wall) was best for the Compoglass restorations and lowest (73.1%) for the RMGI restorations. Hygroscopic expansion was more effective in compensating shrinkage stress than would be assumed based on total shrinkage, because only post-gel shrinkage needed compensation. Effective expansion is therefore hygroscopic expansion minus post-gel shrinkage.

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Response to Letter to the Editor: Toward a Multifactorial Model of Caries Formation

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Structural and functional associations of the rostral anterior cingulate cortex with subjective happiness

Publication date: 1 July 2016
Source:NeuroImage, Volume 134
Author(s): Masahiro Matsunaga, Hiroaki Kawamichi, Takahiko Koike, Kazufumi Yoshihara, Yumiko Yoshida, Haruka K. Takahashi, Eri Nakagawa, Norihiro Sadato
Happiness is one of the most fundamental human goals, which has led researchers to examine the source of individual happiness. Happiness has usually been discussed regarding two aspects (a temporary positive emotion and a trait-like long-term sense of being happy) that are interrelated; for example, individuals with a high level of trait-like subjective happiness tend to rate events as more pleasant. In this study, we hypothesized that the interaction between the two aspects of happiness could be explained by the interaction between structure and function in certain brain regions. Thus, we first assessed the association between gray matter density (GMD) of healthy participants and trait-like subjective happiness using voxel-based morphometry (VBM). Further, to assess the association between the GMD and brain function, we conducted functional magnetic resonance imaging (MRI) using the task of positive emotion induction (imagination of several emotional life events). VBM indicated that the subjective happiness was positively correlated with the GMD of the rostral anterior cingulate cortex (rACC). Functional MRI demonstrated that experimentally induced temporal happy feelings were positively correlated with subjective happiness level and rACC activity. The rACC response to positive events was also positively correlated with its GMD. These results provide convergent structural and functional evidence that the rACC is related to happiness and suggest that the interaction between structure and function in the rACC may explain the trait–state interaction in happiness.



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Reinforcement learning of self-regulated sensorimotor β-oscillations improves motor performance

Publication date: 1 July 2016
Source:NeuroImage, Volume 134
Author(s): G. Naros, I. Naros, F. Grimm, U. Ziemann, A. Gharabaghi
Self-regulation of sensorimotor oscillations is currently researched in neurorehabilitation, e.g. for priming subsequent physiotherapy in stroke patients, and may be modulated by neurofeedback or transcranial brain stimulation. It has still to be demonstrated, however, whether and under which training conditions such brain self-regulation could also result in motor gains.Thirty-two right-handed, healthy subjects participated in a three-day intervention during which they performed 462 trials of kinesthetic motor-imagery while a brain–robot interface (BRI) turned event-related β-band desynchronization of the left sensorimotor cortex into the opening of the right hand by a robotic orthosis. Different training conditions were compared in a parallel-group design: (i) adaptive classifier thresholding and contingent feedback, (ii) adaptive classifier thresholding and non-contingent feedback, (iii) non-adaptive classifier thresholding and contingent feedback, and (iv) non-adaptive classifier thresholding and non-contingent feedback. We studied the task-related cortical physiology with electroencephalography and the behavioral performance in a subsequent isometric motor task.Contingent neurofeedback and adaptive classifier thresholding were critical for learning brain self-regulation which, in turn, led to behavioral gains after the intervention. The acquired skill for sustained sensorimotor β-desynchronization correlated significantly with subsequent motor improvement. Operant learning of brain self-regulation with a BRI may offer a therapeutic perspective for severely affected stroke patients lacking residual hand function.



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Task-based neurofeedback training: A novel approach toward training executive functions

Publication date: 1 July 2016
Source:NeuroImage, Volume 134
Author(s): S.M. Hadi Hosseini, Mika Pritchard-Berman, Natasha Sosa, Angelica Ceja, Shelli R. Kesler
Cognitive training is an emergent approach to improve cognitive functions in various neurodevelopmental and neurodegenerative diseases. However, current training programs can be relatively lengthy, making adherence potentially difficult for patients with cognitive difficulties. Previous studies suggest that providing individuals with real-time feedback about the level of brain activity (neurofeedback) can potentially help them learn to control the activation of specific brain regions. In the present study, we developed a novel task-based neurofeedback training paradigm that benefits from the effects of neurofeedback in parallel with computerized training. We focused on executive function training given its core involvement in various developmental and neurodegenerative diseases. Near-infrared spectroscopy (NIRS) was employed for providing neurofeedback by measuring changes in oxygenated hemoglobin in the prefrontal cortex.Of the twenty healthy adult participants, ten received real neurofeedback (NFB) on prefrontal activity during cognitive training, and ten were presented with sham feedback (SHAM). Compared with SHAM, the NFB group showed significantly improved executive function performance including measures of working memory after four sessions of training (100min total). The NFB group also showed significantly reduced training-related brain activity in the executive function network including right middle frontal and inferior frontal regions compared with SHAM. Our data suggest that providing neurofeedback along with cognitive training can enhance executive function after a relatively short period of training. Similar designs could potentially be used for patient populations with known neuropathology, potentially helping them to boost/recover the activity in the affected brain regions.



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Letter to the Editor: Toward a Multifactorial Model of Caries Formation

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From Artisanal to CAD-CAM Blocks: State of the Art of Indirect Composites

Indirect composites have been undergoing an impressive evolution over the last few years. Specifically, recent developments in computer-aided design–computer-aided manufacturing (CAD-CAM) blocks have been associated with new polymerization modes, innovative microstructures, and different compositions. All these recent breakthroughs have introduced important gaps among the properties of the different materials. This critical state-of-the-art review analyzes the strengths and weaknesses of the different varieties of CAD-CAM composite materials, especially as compared with direct and artisanal indirect composites. Indeed, new polymerization modes used for CAD-CAM blocks—especially high temperature (HT) and, most of all, high temperature–high pressure (HT-HP)—are shown to significantly increase the degree of conversion in comparison with light-cured composites. Industrial processes also allow for the augmentation of the filler content and for the realization of more homogeneous structures with fewer flaws. In addition, due to their increased degree of conversion and their different monomer composition, some CAD-CAM blocks are more advantageous in terms of toxicity and monomer release. Finally, materials with a polymer-infiltrated ceramic network (PICN) microstructure exhibit higher flexural strength and a more favorable elasticity modulus than materials with a dispersed filler microstructure. Consequently, some high-performance composite CAD-CAM blocks—particularly experimental PICNs—can now rival glass-ceramics, such as lithium-disilicate glass-ceramics, for use as bonded partial restorations and crowns on natural teeth and implants. Being able to be manufactured in very low thicknesses, they offer the possibility of developing innovative minimally invasive treatment strategies, such as "no prep" treatment of worn dentition. Current issues are related to the study of bonding and wear properties of the different varieties of CAD-CAM composites. There is also a crucial need to conduct clinical studies. Last, manufacturers should provide more complete information regarding their product polymerization process, microstructure, and composition, which significantly influence CAD-CAM material properties.

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Plasma of Argon Affects the Earliest Biological Response of Different Implant Surfaces: An In Vitro Comparative Study

The aim of this in vitro study was to evaluate the early cell response and protein adsorption elicited by the argon plasma treatment of different commercially available titanium surfaces via a chair-side device. Sterile disks made of grade 4 titanium (n = 450, 4-mm diameter) with 3 surface topographies (machined, plasma sprayed, and zirconia blasted and acid etched) were allocated to receive 4 testing treatments (2% and 10% protein adsorption and cell adhesion with MC3T3-E1 and MG-63). Furthermore, the specimens were divided to undergo 1) argon plasma treatment (10 W, 1 bar for 12 min) in a plasma reactor, 2) ultraviolet (UV) light treatment for 2 h (positive control group), or 3) no treatment (control group). Pretreatment surface analyses based on a scanning electron microscope and profilometer images were also performed. Profilometric analysis demonstrated that the evaluated specimens perfectly suit the standard parameters. The use of argon plasma was capable of affecting the quantity of proteins adsorbed on the different surfaces, notwithstanding their roughness or topographic features at a low fetal bovine serum concentration (2%). UV light treatment for 2 h attained similar results. Moreover, both the plasma of argon and the UV light demonstrated a significant increase in the number of osteoblasts adherent at 10 min in all tested surfaces. Within its limitations, this in vitro study highlights the potential biological benefits of treating implant surfaces with plasma of argon or UV, irrespective of the roughness of the titanium surface. However, in vivo experiments are needed to confirm these preliminary data and settle the rationale of a treatment that might be clinically relevant in case of bone-reparative deficiencies.

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Nonthermal Atmospheric Plasmas in Dental Restoration

It is well known that the service life of contemporary composite restoration is unsatisfactory, and longevity of dentin bonding is one of the major culprits. Bonding is essentially a hybridization process in which dental substrate and adhesive resin interact with each other through an exchange process. Thus, the longevity of dentin bonding can only be improved with enhanced qualities in substrate, adhesive resin, and their interaction within the hybridization zone. This review aims to collect and summarize recent advances in utilizing nonthermal atmospheric plasmas (NTAPs)—a novel technology that delivers highly reactive species in a gaseous medium at or below physiologic temperature—to improve the durability of dentin bonding by addressing these 3 issues simultaneously. Overall, NTAP has demonstrated efficacies in improving a number of critical properties for dentin bonding, including deactivation of oral pathogens, modification of surface chemistry/properties, resin polymerization, improvement in adhesive-dentin interactions, and establishment of auxiliary bonding mechanism. While a few preliminary studies have indicated the benefit of NTAP to bond strength and stability, additional researches are warranted to employ knowledge acquired so far and to evaluate these properties in a systematic way.

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Dont Know Cant Do Wont Change: Barriers to Moving Knowledge to Action in Managing the Carious Lesion

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A Randomized Clinical Trial Evaluating rh-FGF-2/{beta}-TCP in Periodontal Defects

Biological mediators have been used to enhance periodontal regeneration. The aim of this prospective randomized controlled study was to evaluate the safety and effectiveness of 3 doses of fibroblast growth factor 2 (FGF-2) when combined with a β-tricalcium phosphate (β-TCP) scaffold carrier placed in vertical infrabony periodontal defects in adult patients. In this double-blinded, dose-verification, externally monitored clinical study, 88 patients who required surgical intervention to treat a qualifying infrabony periodontal defect were randomized to 1 of 4 treatment groups—β-TCP alone (control) and 0.1% recombinant human FGF-2 (rh-FGF-2), 0.3% rh-FGF-2, and 0.4% rh-FGF-2 with β-TCP—following scaling and root planing of the tooth prior to a surgical appointment. Flap surgery was performed with EDTA conditioning of the root prior to device implantation. There were no statistically significant differences in patient demographics and baseline characteristics among the 4 treatment groups. When a composite outcome of gain in clinical attachment of 1.5 mm was used with a linear bone growth of 2.5 mm, a dose response pattern detected a plateau in the 0.3% and 0.4% rh-FGF-2/β-TCP groups with significant improvements over control and 0.1% rh-FGF-2/β-TCP groups. The success rate at 6 mo was 71% in the 2 higher-concentration groups, as compared with 45% in the control and lowest treatment groups. Percentage bone fill in the 2 higher-concentration groups was 75% and 71%, compared with 63% and 61% in the control and lowest treatment group. No increases in specific antibody to rh-FGF-2 were detected, and no serious adverse events related to the products were reported. The results from this multicenter trial demonstrated that the treatment of infrabony vertical periodontal defects can be enhanced with the addition of rh-FGF-2/β-TCP (ClinicalTrials.gov NCT01728844).

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Surface Engineering of Nanostructured Titanium Implants with Bioactive Ions

Surface nanofeatures and bioactive ion chemical modification are centrally important in current titanium (Ti) oral implants for enhancing osseointegration. However, it is unclear whether the addition of bioactive ions definitively enhances the osteogenic capacity of a nanostructured Ti implant. We systematically investigated the osteogenesis process of human multipotent adipose stem cells triggered by bioactive ions in the nanostructured Ti implant surface. Here, we report that bioactive ion surface modification (calcium [Ca] or strontium [Sr]) and resultant ion release significantly increase osteogenic activity of the nanofeatured Ti surface. We for the first time demonstrate that ion modification actively induces focal adhesion development and expression of critical adhesion–related genes (vinculin, talin, and RHOA) of human multipotent adipose stem cells, resulting in enhanced osteogenic differentiation on the nanofeatured Ti surface. It is also suggested that fibronectin adsorption may have only a weak effect on early cellular events of mesenchymal stem cells (MSCs) at least in the case of the nanostructured Ti implant surface incorporating Sr. Moreover, results indicate that Sr overrides the effect of Ca and other important surface factors (i.e., surface area and wettability) in the osteogenesis function of various MSCs (derived from human adipose, bone marrow, and murine bone marrow). In addition, surface engineering of nanostructured Ti implants using Sr ions is expected to exert additional beneficial effects on implant bone healing through the proper balancing of the allocation of MSCs between adipogenesis and osteogenesis. This work provides insight into the future surface design of Ti dental implants using surface bioactive ion chemistry and nanotopography.

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Pragmatic RCT on the Efficacy of Proximal Caries Infiltration

Proximal caries infiltration has been shown to be efficacious in hampering caries lesion progression when performed by dentists working in a university setting. The aim of this randomized split-mouth, placebo-controlled clinical trial was to assess the efficacy of resin infiltration of proximal caries lesions being performed by several dentists in private practices, in combination with individualized oral hygiene plus noninvasive measures compared with these alone. In this study, 87 children and young adults (with 238 pairs of proximal caries lesions radiographically extending into the inner half of the enamel [E2] or the outer third of the dentin [D1]) were randomly allocated to either 1 of 2 treatments. Test lesions were infiltrated, and a mock treatment was performed in control lesions by 5 German private practitioners. All patients received instructions for a noncariogenic diet, flossing and fluoridation, and individualized noninvasive interventions. The primary outcome was radiographic lesion progression (pairwise comparison) evaluated independently by 2 evaluators who were blinded to treatment allocation. After approximately 10 mo (mean ± SD 307 ± 43 d), 92 of 148 lesion pairs in 24 of 38 treated patients who were at high caries risk could be re-evaluated clinically as well as radiographically using individualized bitewing holders, as at baseline; 186 of 204 lesion pairs in 70 of 77 patients (35 of 38 high-risk patients) could be evaluated after 18 mo (mean 542 ± 110 d). No unwanted effects were observed. After 10 mo, progression was recorded in 2 of 92 test lesions (2%) and in 22 of 92 control lesions (24%) (P = 0.001, McNemar/Obuchowski test; relative risk reduction, 91; 95% confidence interval, 62%–98%). After 18 mo, lesion progression was recorded in all included patients in 10 of 186 test lesions (5%) and in 58 of 186 control lesions (31%) (P < 0.001; relative risk reduction, 83; 95% confidence interval, 67%–91%). Thus, resin infiltration seems to be more efficacious in reducing lesion progression compared with individualized noninvasive measures alone over a period of 18 mo when performed in a private practice setting by various practitioners (German Clinical Trials Register / Deutsches Register Klinischer Studien DRKS00009963).

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Laboratory Studies of Nonlinear Optical Signals for Caries Detection

Multiphoton confocal microscopy and nonlinear spectroscopy are used to investigate the caries process in dentin. Although dentin is a major calcified tissue of the teeth, its organic phase comprises type I collagen fibers. Caries drive dentin demineralization and collagen denaturation. Multiphoton microscopy is a powerful imaging technique: the biological materials are transparent to infrared frequencies and can be excited to penetration depths inaccessible to 1-photon confocal microscopy. The laser excitation greatly reduces photodamage to the sole focal region, and the signal-to-noise ratio is improved significantly. The method has been used to follow pathologic processes involving collagen fibrosis or collagen destruction based on their 2-photon excited fluorescence (2PEF) emission and second harmonic generation (SHG). Combining multiphoton imaging with nonlinear spectroscopy, we demonstrate that both 2PEF and SHG intensity of human dentin are strongly modified during the tooth caries process, and we show that the ratio between SHG and 2PEF signals is a reliable parameter to follow dental caries. The ratio of the SHG/2PEF signals measured by nonlinear optical spectroscopy provides valuable information on the caries process, specifically on the degradation of the organic matrix of dentin. The goal is to bring these nonlinear optical signals to clinical application for caries diagnosis.

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Dental Surface Texture Characterization Based on Erosive Tooth Wear Processes

The differential diagnosis of dental wear lesions affects their clinical management. We hypothesized that surface texture parameters can differentiate simulated erosion, abrasion, and erosion-abrasion lesions on human enamel and dentin. This in vitro study comprised 2 parts (both factorial 4 x 2), with 4 lesion types (erosion, abrasion, erosion-abrasion, and sound [no lesion; control]) and 2 substrates (enamel and dentin). Flattened/polished dental specimens were used in part 1, whereas natural dental surfaces were used in part 2. Testing surfaces were evaluated in blind conditions, using average surface roughness (Sa) and the following scale-sensitive fractal analysis parameters: area-scale fractal complexity (Asfc), exact proportion length-scale anisotropy of relief (eplsar), scale of maximum complexity (Smc), and textural fill volume (Tfv). Two-way analyses of variance, followed by Fisher's protected least significant difference tests (α = 0.05), were used to evaluate the effects of lesion and substrate. Classification trees were constructed to verify the strength of potential associations of the tested parameters. In part 1, Asfc, Sa, and Tfv were able to differentiate erosion and erosion-abrasion lesions from the sound (no lesion) control in both substrates; only Asfc differentiated erosion and erosion-abrasion enamel lesions (all P < 0.05). The best association of parameters correctly classified up to 84% and 94% of the lesions on enamel and dentin, respectively. In part 2, only Asfc differentiated erosion and erosion-abrasion lesions from the sound (no lesion) control in both substrates, whereas eplsar was able to differentiate erosion from erosion-abrasion (all P < 0.05). The association of parameters correctly classified up to 81% and 91% of the lesions in enamel and dentin, respectively. Asfc, Sa, and Tfv were able to differentiate erosion and erosion-abrasion lesions, despite their complicated surface textures. The association of parameters improved the differentiation of lesions for both enamel and dentin in polished or natural surfaces.

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Evidence for Bicarbonate Secretion by Ameloblasts in a Novel Cellular Model

Formation and growth of hydroxyapatite crystals during amelogenesis generate a large number of protons that must be neutralized, presumably by HCO₃^– ions transported from ameloblasts into the developing enamel matrix. Ameloblasts express a number of transporters and channels known to be involved in HCO₃^– transport in other epithelia. However, to date, there is no functional evidence for HCO₃^– transport in these cells. To address questions related to HCO₃^– export from ameloblasts, we have developed a polarized 2-dimensional culture system for HAT-7 cells, a rat cell line of ameloblast origin. HAT-7 cells were seeded onto Transwell permeable filters. Transepithelial resistance was measured as a function of time, and the expression of transporters and tight junction proteins was investigated by conventional and quantitative reverse transcription polymerase chain reaction. Intracellular pH regulation and HCO₃^– transport were assessed by microfluorometry. HAT-7 cells formed epithelial layers with measureable transepithelial resistance on Transwell permeable supports and expressed claudin-1, claudin-4, and claudin-8—key proteins for tight junction formation. Transport proteins previously described in maturation ameloblasts were also present in HAT-7 cells. Microfluorometry showed that the HAT-7 cells were polarized with a high apical membrane CO₂ permeability and vigorous basolateral HCO₃^– uptake, which was sensitive to Na⁺ withdrawal, to the carbonic anhydrase inhibitor acetazolamide and to H₂DIDS inhibition. Measurements of transepithelial HCO₃^– transport showed a marked increase in response to Ca²⁺- and cAMP-mobilizing stimuli. Collectively, 2-dimensional HAT-7 cell cultures on permeable supports 1) form tight junctions, 2) express typical tight junction proteins and electrolyte transporters, 3) are functionally polarized, and 4) can accumulate HCO₃^– ions from the basolateral side and secrete them at the apical membrane. These studies provide evidence for a regulated, vectorial, basolateral-to-apical bicarbonate transport in polarized HAT-7 cells. We therefore propose that the HAT-7 cell line is a useful functional model for studying electrolyte transport by ameloblasts.

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