Peter Ngan

Objectives: This retrospective study aimed to assess the skeletal and dental effects of the Carriere ^® motion 3D ^™ appliance (CMA) followed by comprehensive orthodontic treatment in Chinese adult patients with Class II malocclusions. Material and Methods: The sample size consisted of 25 post-pubertal patients treated with CMA, followed by comprehensive orthodontic therapy with fixed appliances ( n = 5) or clear aligners ( n = 20). Lateral cephalometric radiographs were collected at 3 time points: Pre-treatment (T1), immediately after Class II correction with the CMA (T2), and immediately after completion of comprehensive orthodontic therapy (T3). Changes between the time points were evaluated using a matched paired t-test. Intra-rater reliability was evaluated with Pearson correlation coefficients. Inter-rater reliability was assessed with an intra-class correlation coefficient. Results: The average treatment time with the CMA was 6.3 ± 1.9 months. The total treatment time together with comprehensive orthodontic therapy was 32.2 ± 6.5 months. During CMA treatment, dentoalveolar movements accounted for 84% of molar correction and 77% of overjet reduction. CMA significantly corrected the overjet by 1.6 mm and molar relationship by 3.1 mm. Dentoalveolar treatment effects of the CMA included 2.2 mm distalization of maxillary molars, 1.6 mm mesialization and 0.7 mm extrusion of mandibular molars, 1.5° retroclination of the maxillary incisors, 5.0° proclination of mandibular incisors, and 2.4° steepening of the occlusal plane. Minor skeletal changes were observed, including a 0.4° decrease in SNB, 0.3° increase in ANB, and 0.6° increase in mandibular plane angle; however, these changes were not clinically significant. Following comprehensive treatment, total overjet correction was 2.5 mm. Molar relationship partially relapsed after CMA removal, with 2.2 mm total correction. Some overbite reduction and mandibular incisor proclination also rebounded. Total angular changes post-treatment included 6.5° retroclination of the maxillary incisors and 2.7° proclination of the mandibular incisors. Conclusion: CMA appliances can effectively improve molar relationships and reduce overjet in adult Class II patients through primarily dentoalveolar movements. The change in molar relationship suggests that CMA may best be used for adult Class II malocclusions that require 2–3 mm of molar correction.

Skeletal Class II patients with concurrent mandibular retrognathia who are still growing, may be treated with removable or fixed functional appliances. The success of treating these patients to an acceptable facial profile and occlusion depends on the amount of remaining growth, the design of the appliance and patient compliance. The objective of this clinical practice review article is to present the literature background of contemporary treatment of Class II malocclusion with mandibular deficiency using a fixed Herbst functional appliance and a removable Invisalign^® with mandibular advancement (MA) clear aligner functional appliance. Both of these appliances sequentially advance the mandible into a forward position for Class II correction. This review is illustrated with a clinical case treated with each type of functional appliance, as examples to demonstrate mechanism of action and treatment outcomes. Overall, both appliances deliver similar outcomes in Class II correction with improvement in convexity of facial profile, skeletal changes in decrease in angle A point-nasion-B point (ANB), increase in angle sella-nasion-B point of mandible (SNB), forward movement of the mandible and minor maxillary restraint. They differ in that the Herbst appliance increased proclination of lower incisors, while Invisalign^® MA controlled the lower incisor inclination. Invisalign^® MA also offered better vertical control. Understanding the mechanisms of action, similarities and differences in treatment outcomes may assist clinicians in selecting the appropriate orthodontic appliance for Class II treatment.

Pycnodysostosis (PYCD) is a rare lysosomal storage disease of the bone caused by a mutation in the gene that codes the enzyme cathepsin K. Patients diagnosed with PYCD demonstrate certain physical characteristics, including deformity in craniofacial structure for which patients seek orthodontic treatments to improve occlusal functions and esthetics. In addition, growth hormone therapy is indicated for these patients due to their short stature. This article is the first to report on the successful completion of the non-surgical orthodontic treatments of a patient diagnosed with PYCD. The patient was treated in two phases due to a waiting period for growth hormone therapy. However, superimposition of pre-and post-treatment radiographs showed no evidence of accelerated skeletal growth at the conclusion of the hormonal therapy. The rate of orthodontic tooth movement for Phase I with conventional appliance and Phase II treatment with clear aligners was similar with healthy individuals treated with four premolars extraction. Surgical exposure of the impacted permanent molars was contraindicated as no posterior dentition was available as anchorage for molar uprighting. Extraction of impacted molars in the mandible was performed with care due to the high risk of fracture. Orthognathic surgery treatment carries an increased risk of osteomyelitis for these patients due to dense bone with poor vascularity. Therefore, non-surgical camouflage orthodontic treatment can be the best option to achieve functional occlusion for patients diagnosed with PYCD.

Objective: Orthodontic treatment often involves four first premolar extractions. There is concern that the retraction of the anterior teeth due to extraction of first premolars may constrict tongue space and will reduce oral cavity and oropharynx space. Constricted airways are often associated with sleep disordered breathing (SDB) and sleep disruption. The aim of this study was to determine if there is an association of SDB factors with the absence of first premolars.Methods: A cross‐sectional study was conducted using National Health and Nutrition Examination Survey (NHANES) 2017‐March 2020 data on participants, aged 18–65 years (n = 4742). Variables of interest included self‐reports of SDB (symptoms of disrupted sleep such as snoring, snorting, daytime sleepiness, and inappropriate number of hours of sleep). Data for the presence/absence of first premolars were gathered from the oral examination section of NHANES. An assumption was made that absence of four first premolars in dentate participants indicated extractions for orthodontic treatment. Data analyses were conducted with Rao Scott chi squared test.Results: There were no significant associations of SDB and symptoms of disrupted sleep associated with the absence of four first premolars in dentate participants.Conclusion: Concerns of the impact of first premolar extractions on SDB were not supported with this study.

Introduction Orthodontic treatment using face mask protraction combined with an alternate rapid maxillary expansion and constriction/protraction face mask (Alt-RAMEC/PFM) protocol is effective in the early treatment of patients with class III malocclusion, but the stability of treatment outcomes represents a major concern. Previous studies have suggested that tonsillar hypertrophy can be a risk factor for class III malocclusion and tonsillectomy may prompt the normalisation of dentofacial growth. However, these studies had a low-to-moderate level of evidence. This study was designed to identify the impact of tonsillectomy before orthodontic treatment on the efficacy and stability of Alt-RAMEC/PFM protocols and the sleep quality and oral health in children with anterior crossbite and tonsillar hypertrophy. Methods and analysis This is a two-arm, parallel-group, superiority cluster randomised controlled trial, with four clinics randomly assigned to the surgery-first arm and the orthodontic-first arm in a 1:1 ratio. The Alt-RAMEC protocol involves alternate activation and deactivation of the expander’s jet screw over 6 weeks to stimulate maxillary suture distraction. Patients will be instructed to wear the PFM for a minimum of 14 hours per day. The primary outcomes are changes in Wits appraisal and the degree of maxillary advancement from baseline to the end of orthodontic treatment. Lateral cephalometric radiographs, polysomnography, Obstructive Sleep Apnoea-18 questionnaire and Oral Health Impact Profile-14 questionnaire will be traced, collected and measured. We will recruit 96 patients intofor the study. To assess differences, repeated multilevel linear mixed modelling analyses will be used. Ethics and dissemination This study has been granted ethical approval by the Ethics Committee of the School & Hospital of Stomatology, Wuhan University (approval No. 2023-D10). Written informed consent will be obtained from the participants and their guardians. The results of the trial will be disseminated through academic conferences and journal publications. Trial registration number ChiCTR2300078833.