Mechanical properties and clinical performance of different brands of nickel titanium archwires following intraoral use: A prospective clinical trial

Objectives: To evaluate the effect of intraoral use of three brands of nickel titanium archwires on their mechanical properties and crowding relief ability. Methods: Three groups (n=39) of 0.016” round NiTi archwires: Dentaurum (A), American Orthodontics (B) and IMD Orthodontics (C) were subdivided according to the intervention (n=13) into: As-received, no intervention (subgroup 1), in-vivo (subgroup 2), and in-vitro (subgroup 3). Plateau slope, resilience, and elastic modulus of all wires were tested using a universal testing machine. The relief of crowding following intraoral use for 8 weeks was assessed using Little’s irregularity index. Results were significant at p ≤ 0.05. Results: For all NiTi brands, the highest plateau slope value; among the subgroups, was recorded following the intraoral use (in-vivo). For the in-vivo wires (subgroup 2), the Dentaurum wires revealed the lowest plateau slope value (0.258 N/mm ±0.032) while the IMD wires revealed the lowest resilience values (36.24 J.mm-3 ±0.6). There was no significant difference in the modulus of elasticity of wires between all 3 subgroups. The Little’s irregularity index decreased over time, and the difference between the groups was not significant. No significant difference was found between the groups in terms of inter-canine width.&nbsp

Dimensional and positional temporomandibular joint osseous characteristics in normodivergent facial patterns with and without temporomandibular disorders

Objective: This study evaluated the dimensional and positional osseous temporomandibular joint features in normodivergent facial patterns with and without temporomandibular disorders. Methods: A total of 165 adult patients were divided into two groups: group 1 (n = 79 patients; 158 joints): temporomandibular disorders patients and group 2 (n = 86 patients; 172 joints): non-temporomandibular disorders patients. Three-dimensional positional and dimensional temporomandibular joint characteristics, including glenoid fossa, mandibular condyles, and joint spaces, were assessed by cone beam computed tomography. Results: The glenoid fossa positions in the three orthogonal planes and height showed statistical significance between the two studied groups. The temporomandibular disorders patients showed higher horizontal and vertical condyle inclinations while anteroposterior inclination was less, and the condyle was positioned more superior, anterior, and lateral in the glenoid fossa. The condyle width and length showed no significance between the two groups, while condyle height was smaller in temporomandibular disorders patients. Anterior and medial joint spaces increased while the superior and posterior joint spaces reduced in temporomandibular disorders patients. Conclusion: There were significant differences between the patients with and without temporomandibular joint disorders in terms of mandibular fossa positions and height as well as condylar positions and inclinations in horizontal and vertical planes together with reduced condylar height and reduced posterior and superior joint spaces in the temporomandibular disorders patients. Clinical relevance: The temporomandibular disorder is a multifactorial disorder in which one of these factors is the dimensional and positional characteristics of the temporomandibular joints; including or excluding this factor requires a comprehensive three-dimensional investigation of patients with TMD compared to the normal group under the condition that the facial pattern is average as a confounding factor.Scopu

Malocclusion and Temporomandibular Disorders: Verification of the Controversy

Aims: To investigate the dental and skeletal aspects of malocclusion in the anteroposterior and vertical dimensions in a sample of temporomandibular disorders (TMD) patients and to correlate these aspects with the signs and symptoms of TMD. Methods: A total of 150 TMD patients were divided into five groups according to the Diagnostic Criteria for TMD: Group 1 = myalgia (M); Group 2 = disc displacement with reduction (DDWR); Group 3 = disc displacement without reduction (DDWOR); Group 4 = degenerative disorders (D); and Group 5 = subluxation (S). Molar and canine relations, overjet, overbite, occlusal guidance, occlusal interferences, and centric slides were recorded for each patient, and the skeletal craniofacial patterns were analyzed for each patient using cone beam computed tomography. One-way analysis of variance was used to compare the variable means of the different groups. Pearson correlation coefficient was used to assess the correlations of quantitative continuous variables. Significance level was considered at P < .05. Results: No significant difference was found among the groups regarding any aspects of dental occlusion except for mediotrusive interferences, which were significantly higher in Group 3 (DDWOR) (P = .02). Regarding skeletal craniofacial pattern, Group 4 (D) had significantly smaller mean ± standard deviation sella-nasion-B (SNB) point angle (74.31 ± 3.04 degrees) than Group 3 (DDWOR) (78.04 ± 4.88 degrees), and Group 1 (M) showed the greatest SNB angle (79.87 ± 3.73 degrees) (P = .03). Group 3 (DDWOR) showed significantly greater mean mandibular plane/SN angle (39.56 ± 6.19 degrees) than Group 1 (M) (34.73 ± 5.65 degrees) (P = .04). Relations between occlusal variables and TMD parameters were nonsignificant. Conclusion: This study provides robust evidence to diminish the TMD-malocclusion association, especially in myogenic types of TMD. © 2019 by Quintessence Publishing Co Inc