Early-stage periodontal ligament compression predicts orthodontically induced root resorption in rats.

OBJECTIVES: To determine the effect of orthodontic pressure on periodontal ligament (PDL) compression in rats and assess correlation between PDL compression and orthodontically induced root resorption (OIRR). MATERIALS AND METHODS: Eight female Wistar rats aged 10 weeks underwent surgery to place 2 mini-screws at the center of the palatal plate. 25 cN coil springs connecting the maxillary first molars and mini-screws were applied bilaterally to generate mesial force. Maxillary first molars were assigned to undergo either bodily or tipping movements. Micro-computed tomography (µCT) scans were taken on days 0, 3, 7, and 14, and histological sections were taken on day 14. OIRR was measured from histological sections, and the corresponding PDL compression ratio was quantified using µCT images. RESULTS: The PDL was compressed by approximately 76% in tipping movement and 55% in bodily movement after 3 days, and by approximately 47% in bodily and tipping movements after 7 days of orthodontic force application. The extent of OIRR in tipping movement was significantly greater than that in bodily movement. A strong positive correlation between OIRR and PDL compression ratio was observed on day 3; however, no correlation was observed on day 7. CONCLUSIONS: A strong correlation between PDL compression ratio and OIRR was observed at an early stage after the application of orthodontic force regardless of the tooth movement type (bodily or tipping), implying the importance of early stage PDL compression in the induction of OIRR.

Oral appliance-generated malocclusion traits during the long-term management of obstructive sleep apnea in adults.

OBJECTIVES: To identify malocclusion characteristics generated after using oral appliances (OAs) for at least 5 years for the management of snoring and obstructive sleep apnea (OSA) in adults. MATERIALS AND METHODS: PubMed, MEDLINE (Ovid), Scopus, CINAHL, and Informit were searched without language restrictions through January 20, 2021. Unpublished literature was searched on ClinicalTrials.gov, the National Research Register, and the Pro-Quest Dissertation Abstracts and Thesis database. Authors were contacted when necessary, and reference lists of the included studies were screened. Risk of bias was assessed through the revised Cochrane Risk of Bias tool for randomized controlled trials (RoB2) and Non-Randomized Studies of Interventions for non-RCTs and uncontrolled before-after studies (ROBINS-I). A random-effects meta-analysis was conducted only on studies that used the same OAs to exclude biomechanical differences. Risk of bias across studies was assessed with the Grading of Recommendations, Assessment, Development and Evaluation tool. RESULTS: A total of 12 studies were included in the final qualitative synthesis. Eight included studies had high, one had moderate, and three had low risks of bias. Significant progressive decreases of overjet (OJ; -1.43 mm; 95% confidence interval [CI], -1.66 to -1.20) and overbite (OB; -1.94 mm; 95% CI, -2.14 to -1.74) associated with maxillary incisor retroclination and mandibular incisor proclination were reported long term. Although most studies showed no sagittal skeletal changes, some degree of vertical skeletal changes were noted. CONCLUSIONS: Based on a very low evidence level, inevitable anterior teeth positional changes seem to be a common long-term adverse effect of OAs. The magnitude of those changes could be considered clinically irrelevant for most pretreatment occlusions, but in occlusions with limited OJ and OB, it may be worth clinical consideration.

Efficiency and Accuracy of Three-Dimensional Models Versus Dental Casts: A Clinical Study.

OBJECTIVE: The aim of this study was to compare the accuracy of digital and plaster model methods and the time required for analysis. METHODS: A total of 30 subjects (20 females, 10 males; mean age, 14.36±6.30 years), who required plaster models for the construction of either a fixed or a removable orthodontic appliance, were randomly selected. As part of the diagnostic records, digital impressions with a three-dimensional (3D) intra-oral scanner (TriosColor-P13 Shape) were taken from all subjects. Conventional impressions for the orthodontic appliances were taken with alginate (Orthoprint, Zhermack, Italy), and the plaster models were obtained (Scheu-Dental, GmbH.D-58642, Iserlohn, Germany). Two groups were formed. In the conventional measurement group, manual measurements were taken on the plaster models, while in the digital measurement group, the 3Shape OrthoAnalyzer 2013 software was used to make the measurements on the 3D models. In both groups, the total time required to perform the Bolton analysis and space analysis was recorded, and the results were compared. RESULTS: There was no statistically significant difference found between the two groups in terms of the measurement values. The total time to perform all the analyses was determined to be shorter with digital models compared to conventional plaster models (p<0.001). CONCLUSION: The Bolton analysis and space analysis measurements carried out on 3D models did not show any statistically significant difference compared to plaster models. The time taken to perform the analyses was shorter using digital models than for conventional plaster models.