Assessment of Anatomical Dentin Thickness in Mandibular First Molar: An In Vivo Cone-Beam Computed Tomographic Study.

Aim: To determine the minimum dentin thickness in the mesial and distal walls of the mesiobuccal (MB) and mesiolingual (ML) canals of the mandibular first molars using cone-beam computed tomography (CBCT). Materials and Methods: CBCT examinations of 624 mandibular first molars from an Indian subpopulation were analyzed. The mesial and distal minimum dentin thickness was evaluated in 1 mm intervals apical to the furcation area. Independent t-test was used to analyze the data (α = 0.05). Using Cohen's kappa coefficient, the interexaminer and intraexaminer reliability was evaluated. Results: The mesial dentin thickness was significantly higher than the distal dentin thickness for MB and ML canals (P=0.01). The average dentin thickness in the distal and mesial plane of the MB canal was 1.15 ± 0.15 mm and 1.52 ± 0.19 mm at the 1 mm level and 0.83 ± 0.13 and 1.08 ± 0.18 at the 5 mm level, respectively. For the ML canal, the average dentin thickness in the distal plane and the mesial plane was 1.24 ± 0.18 mm and 1.44 ± 0.21 at the 1 mm level and 0.91 ± 0.16 and 1.01 ± 0.17 at the 5 mm level, respectively. Statistical analysis between the MB and ML canals showed significant differences in the dentin thickness at 4 and 5 mm levels in both the distal and the mesial planes (P=0.01). In more than 85% of the cases, the minimum dentin thickness was seen at the 5 mm level in both the distal and mesial planes in MB and ML canals. Conclusion: The distal planes of the mesiolingual and mesiobuccal canals were thinner in most cases, making the distal surface more prone to iatrogenic perforations. Considerably, at 4 and 5 mm from the furcation, the distal wall was significantly thinner than the mesial walls. Understanding the anatomy of the danger zone in the mesial roots of the mandibular first molars may serve to minimize the risk of endodontic mishaps such as strip perforations.

Electromyographic Assessment of Muscle Activity in Children Undergoing Orthodontic Treatment-A Systematic Review.

Background: Surface electromyography (sEMG) can provide an objective and quantitative image of the functional state of neuromuscular balance in the stomatognathic system. The objective of this systematic review is to examine current scientific evidence regarding the effects of orthodontic treatment on muscle electromyographic (EMG) activity in children. Methods: The search strategy included the PubMed, PubMed Central, Web of Science, Scopus, and Embase databases. The inclusion criteria were studies assessing EMG muscle activity in children undergoing orthodontic treatment compared with untreated children. The Cochrane risk-of-bias tool (RoB2) and the Newcastle-Ottawa Scale (NOS) were used to evaluate the quality of the studies. The quality of evidence assessment was performed using GRADE analysis. The PRISMA diagram visually represented the search strategy, as well as screening and inclusion process. Results: The search strategy identified 540 potential articles. Fourteen papers met the inclusion criteria. Six studies were judged at a low risk of bias. The certainty of evidence was rated as moderate to low, according to the GRADE criteria. Studies showed alterations in EMG muscle activity in children undergoing orthodontic treatment. Conclusions: Orthodontic treatment appears to affect muscle activity in children undergoing orthodontic treatment. However, the quality of evidence is low and, therefore, it is not possible to definitively state this effect. Further long-term studies are needed to confirm the findings of this review. Study protocol number in PROSPERO database: CRD42023491005.

In-vivo assessment of application of folinic acid and botulinum toxin A in cleft lip surgical defects.

INTRODUCTION: Folinic acid and botulinum toxin A have shown promising results in wound healing in different studies. This study aimed to compare the effects of these approaches on wound healing after simulating cleft lip surgery in rats. METHODS: In this experimental animal study, after creating lip defects, 30 rats were randomly divided into three groups and received normal saline (CTL), botulinum toxin A (BOT), and folinic acid (FOL). Biopsy from the skin wounds was performed after 14- and 28-days. These samples were stained with haematoxylin and eosin and Masson trichrome staining. Finally, each pathological parameter of wound healing was rated in this study. RESULTS: While the inflammatory response was not different among the study groups, fibroblast proliferation and collagen deposition were significantly higher in FOL group compared to BOT group. Moreover, both BOT and FOL facilitated epithelial healing and 14-day angiogenesis as compared with normal saline. CONCLUSIONS: Improved wound healing was observed using both botulinum toxin A and folinic acid in rat animal models. However, the application of botulinum toxin A caused less fibroblast proliferation and collagen deposition which can potentially lead to less scar formation, which can be particularly important in the aesthetic zone.

Assessment of Apical Pressures in Single and Joining Canals - An Ex Vivo Study Based on Computational Fluid Dynamic Analysis.

OBJECTIVE: Computational fluid dynamic analysis (CFD) is claimed to be a reliable tool for analysing the fluid flow and the generated apical pressures in the simulated root canal. The current study aimed to analyse the apical pressures in extracted teeth with single and joining canals. METHODS: Forty-six freshly extracted teeth were collected for the present study. The power was set at 95%, with an effect size of 0.55 (1-ß=95%, α=0.05). Once the root canal anatomy was confirmed with cone-beam computed tomography (CBCT), they were divided into two groups: group I: mandibular second premolars with Vertucci type-I (n=23), and group II: maxillary second premolars with Vertucci type-II (n=23). The instrumentation of the specimens was carried out to a 0.04-taper using rotary instruments. A post-instrumentation CBCT was obtained, and computer-aided design models were obtained. The CFD simulations were then con- ducted with simulated 30-gauge side vented needles at 25, 50, and 75% short of the working length (WL). RESULTS: Group I recorded significantly (p<0.05) higher apical pressures at needle positions 25% short of the WL. However, no significant differences were elicited in the groups at other needle positions. CONCLUSION: Single canal specimens recorded higher apical pressures at needle positions 25% short of the WL. However, no differences were elicited between single and joining canals at higher needle positions.

Surface electromyography in the assessment of masticatory muscle activity in patients with pain-related temporomandibular disorders: a systematic review.

Background: Temporomandibular disorders (TMD) are a set of painful conditions affecting the orofacial region that are prevalent and constitute the most frequent type of non-dental pain complaint in the maxillofacial area. Pain-related TMD (TMD-P) is characterized by ongoing pain in the masticatory muscles, the temporomandibular joint, or surrounding structures. Due to the multiple factors that contribute to the development of this condition, it can be challenging to accurately diagnose. One of the useful method for assessing patients with TMD-P is surface electromyography (sEMG). The aim of this systematic review was to provide a comprehensive overview of the current scientific literature on the evaluation of masticatory muscle activity (MMA) in individuals diagnosed with TMD-P, through the utilization of sEMG. Methods: To gather relevant information, electronic databases such as PubMed, Web of Science, Scopus, and Embase were searched using specific keywords including: "pain" AND ("temporomandibular disorder*" OR "temporomandibular dysfunction*") AND "surface electromyography" AND "masticatory muscle activity." The inclusion criteria were studies assessing MMA in patients with TMD-P using sEMG. The Effective Public Health Practice Project (EPHPP) Quality Assessment Tool for Quantitative Studies was utilized to evaluate the quality of the studies that were included in the review. Results: The search strategy identified 450 potential articles. Fourteen papers met the inclusion criteria. Global quality rating for significant part of the articles was weak. Most studies showed greater sEMG activity of the masseter (MM) and temporal anterior (TA) muscles at rest in TMD-P subjects than in the asymptomatic controls, while the MM and TA muscles were less active in the pain-related TMD group compared to the non-TMD group during maximal voluntary clenching (MVC). Conclusion: There were differences in MMA in the TMD-pain population compared to a healthy control group during various tasks. The diagnostic efficacy of surface electromyography in assessing individuals with TMD-P remains unclear.

Three-Dimensional Assessment of Temporomandibular Joint Morphology and Facial Asymmetry in Individuals with Different Vertical Skeletal Growth Patterns.

The aim of the current study was to investigate, by means of Cone-Beam Computed Tomography (CBCT), condyle−fossa relationship, temporomandibular joint (TMJ) morphology and facial asymmetry in subjects with different vertical skeletal growth patterns. CBCT of 56 patients (112 TMJs) were categorized into three groups according to the mandibular plane angle (MP): Hypodivergent (MP ≤ 23°), Normodivergent (23° < MP < 30°), and Hyperdivergent (MP ≥ 30°). TMJ spaces, width and depth of the condyle and thickness of the fossa were measured. Horizontal and vertical measurements were used to assess facial asymmetry. One-way Analysis of Variance (ANOVA) and post-hoc Turkey tests were computed for the between-groups comparison. Statistical significance was set at p < 0.05. Larger anterior joint space and smaller condylar dimensions (medio-lateral diameter and medio-lateral thickness) were observed in the hyperdivergent group compared to the normodivergent and hypodivergent groups. Right condylar distances to midsagittal plane were significantly larger than left distances in all the three groups. A vertical pattern of growth in healthy individuals seems to be associated with condylar position and dimension, while facial asymmetry values do not differ among different vertical groups.