Young patients with DM1 had already from the beginning a more retrognathic profile and hyperdivergent skeletal aberration with a steep mandibular plane and large intermaxillary angle when compared with healthy individuals. The intermaxillary angle did not decrease during the observation period, contrary to what was observed in healthy individuals.

Objective: To assess the efficacy of lingual orthodontics by comparing setups and post-treatment casts.Setting and sample population: Thirty-two consecutive patients treated with a customized lingual orthodontic appliance were included in this retrospective study. Materials and methods:Initial casts, post-treatment casts and setups were scanned, and the digital models produced were analysed in terms of overjet; overbite; molar and canine relationships; intercanine, interpremolar and intermolar distances; upper and lower arch lengths; midline deviation; bucco-lingual angulation of all teeth and mesio-distal angulation of anterior teeth. Comparisons between setups and posttreatment casts were performed via paired t tests. Relationships between the planned and actual correction were studied using regression analysis.Results: Statistically significant differences in bucco-lingual torque between setups and post-treatment casts were found for all upper teeth, except for central incisors.In the lower jaw, statistically significant differences in bucco-lingual torque were found between setups and post-treatment casts for the lower incisors and molars.No statistically significant differences in mesio-distal angulation of anterior teeth were found between setups and post-treatment casts. Upper and lower arch widths did not vary significantly between setups and final casts, except upper inter-second premolar and intermolar distances. Conclusion:Customized lingual appliances offer efficient control of mesio-distal angulation of all anterior teeth. Significant differences in torque between setups and post-treatment casts were observed for upper lateral incisors, canines, premolars and molars, as well as lower incisors and molars. However, the torque difference was clinically significant (over three degrees) for upper second premolars and molars only.

Summary Background/objectives This research aimed to study the malocclusions of children and adolescents with myotonic dystrophy type 1 (DM1), in respect to healthy individuals, and trace the occlusal changes that occurred in these individuals during growth. Materials/methods Thirty-six dental casts, from children and adolescents with DM1 living in western and southern Sweden, were compared with a control group of 50 healthy individuals. To identify potential changes in occlusal traits, 26 casts were assessed and followed-up over a median time of 9 years. Independent samples t-tests were used to compare the two groups and their changes over time. Paired samples t-tests tested changes over time within each group (P < 0.05). Results DM1 patients had a higher prevalence of anterior open bite, posterior crossbite, and Class III malocclusions. When compared to controls, patients presented smaller upper and lower intermolar as well as intercanine widths. In both groups, the individuals revealed longitudinal changes with a decrease in both upper and lower arch lengths and an increase on the palatal vault height. During the follow-up period, the prevalence of malocclusions remained almost the same, only significantly differing regarding the changes that occurred between groups referred to the upper intermolar width, which decreased among DM1 patients. Conclusions/implications In comparison to healthy controls, children and adolescents with DM1 have shown already at an early age a higher prevalence of both anterior open bite and posterior crossbite. These occlusal traits did not change with time apart from the upper narrow intermolar width, which further decreased with time.