Effects of low-intensity laser therapy on the stability of orthodontic mini-implants: a randomised controlled clinical trial

Objective: To investigate the effect of low-intensity laser therapy on mini-implant stability using resonance frequency analysis during canine retraction with fixed appliances. Design: A split-mouth randomised clinical trial. Setting: Subjects were recruited and treated in the outpatient clinic, Department of Orthodontics, Faculty of Dentistry, Cairo University. Participants: Fifteen subjects with mean age 20.9 (±3.4) years who required extraction of maxillary first premolar teeth and mini-implant-supported canine retraction. Methods: Thirty orthodontic mini-implants were inserted bilaterally in the maxillary arches of recruited subjects following alignment and levelling. Mini-implants were immediately loaded with a force of 150 g using nickel titanium coil springs with split-mouth randomisation to a low-intensity laser-treated side and control side. The experimental sides were exposed to low-intensity laser therapy from a diode laser with a wavelength of 940 nm at (0, 7, 14, 21 days) after mini-implant placement. Mini-implant stability was measured using resonance frequency analysis at (0, 1, 2, 3, 4, 6, 8, 10 weeks) after implant placement. Results: A total sample of 28 mini-implants were investigated with 14 in each group. Clinically, both mini-implant groups had the same overall success rate of 78.5%. There were no significant differences in resonance frequency scores between low-intensity laser and control sides from baseline to week 2. However, from week 3 to 10, the low-intensity laser sides showed significantly increased mean resonance frequency values compared to control (P > 0.05). Conclusions: Despite evidence of some significant differences in resonance frequency between mini-implants exposed to low-intensity laser light over a 10 weeks period there were no differences in mini-implant stability. Low-intensity laser light cannot be recommended as a clinically useful adjunct to promoting mini-implant stability during canine retraction

Global distribution of malocclusion traits: A systematic review

Objective: Considering that the available studies on prevalence of malocclusions are local or national-based, this study aimed to pool data to determine the distribution of malocclusion traits worldwide in mixed and permanent dentitions. Methods: An electronic search was conducted using PubMed, Embase and Google Scholar search engines, to retrieve data on malocclusion prevalence for both mixed and permanent dentitions, up to December 2016. Results: Out of 2,977 retrieved studies, 53 were included. In permanent dentition, the global distributions of Class I, Class II, and Class III malocclusion were 74.7% [31–97%], 19.56% [2–63%] and 5.93% [1–20%], respectively. In mixed dentition, the distributions of these malocclusions were 73% [40–96%], 23% [2–58%] and 4% [0.7–13%]. Regarding vertical malocclusions, the observed deep overbite and open bite were 21.98% and 4.93%, respectively. Posterior crossbite affected 9.39% of the sample. Africans showed the highest prevalence of Class I and open bite in permanent dentition (89% and 8%, respectively), and in mixed dentition (93% and 10%, respectively), while Caucasians showed the highest prevalence of Class II in permanent dentition (23%) and mixed dentition (26%). Class III malocclusion in mixed dentition was highly prevalent among Mongoloids. Conclusion: Worldwide, in mixed and permanent dentitions, Angle Class I malocclusion is more prevalent than Class II, specifically among Africans; the least prevalent was Class III, although higher among Mongoloids in mixed dentition. In vertical dimension, open bite was highest among Mongoloids in mixed dentition. Posterior crossbite was more prevalent in permanent dentition in Europe

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