Accuracy of indirect bracket placement with medium-soft, transparent, broad-coverage transfer trays fabricated using computer-aided design and manufacturing: An in-vivo study.

INTRODUCTION: The objective of this study was to test the precision of in-vivo indirect bracket placement via medium-soft, transparent, broad-coverage, computer-aided designed and manufactured transfer trays using an automated digital method. METHODS: Seventeen patients requiring vestibular fixed appliances were consecutively recruited, and bonding accuracy was measured at each bracket, evaluating 3 linear (mesiodistal, buccolingual, and vertical) and 3 angular measurements (torque, tip, and rotation) with an automated method involving digital superimposition of individual teeth. Mean and standard deviation values were calculated for both arches, single arch, and tooth type, and the percentages of single deviations over the thresholds of 0.25 mm and 1° were calculated, as well as maximum and minimum values for each deviation and directional bias. Correlations between each variable (arch, tooth type, and single tooth) and deviations were investigated through classification and regression trees (CART) predictive models. RESULTS: Neither mean nor single linear deviations ever exceeded the set cutoff value of 0.25 mm. Mean angular deviations never exceeded 1°, but some individual angular deviations did, specifically 8.31% of torque, 13.16% of tip, and 7.16% of rotation deviations. The highest percentage of deviation was recorded for rotation of the maxillary incisors (18.11%). No evident trend in directional deviation bias was found. Tooth type appears to influence mesiodistal and torque deviations, whereas the single tooth variable influenced the percentage of rotation deviations exceeding 1° (P <0.05). CONCLUSIONS: This computer-aided designed and manufactured medium-soft, transparent transfer tray provides accurate bracket placement and could be recommended for routine fixed appliance treatment.

Dentoalveolar Effects Following Maxillary Expansion: Comparison Between Dental and Skeletal Anchorage

ABSTRACT Objective: To compare the dento-alveolar effects between dental and skeletal anchored expansion devices to achieve maxillary expansion in different groups of patients: pure dental anchorage was used in growing patients and skeletal anchorage in adult patients. Linear, angular and volumetric parameters have been analysed. Material and Methods: 22 patients has been selected from the total archive of patients treated in the Orthodontics Department of the University of Ferrara, Italy, divided into 3 groups according to the appliance used to obtain the transversal maxillary correction. Digital files of the upper arch were obtained from scans performed using an intro-oral scanner before treatment (T0) and at the end of expansion (T1). Therefore, linear, angular and volumetric measurements have been performed. Results: There is a highly significant statistic variation of the 3-3, 4-4 and 6-6 diameter as a function of time. There was a statistically significant variation of the palatal vault angle and of the 6-6 distance at the cusp level as a function of time. Moreover, it appears that these parameters are reduced in the group with skeletal anchored expander. No tooth considered have encountered a statistically significant change in tip and torque values, no matter the type of RPE and the treatment time. For all patients, we have recorded the superimposition of the maxillary dental cast before and after treatment. Conclusion: In all patients, we obtained a resolution of the maxillary transverse deficit. Patients treated by pure skeletal anchored devices have recorded a less variations of palatal vault angle and the distance between first molar cusps, as if the expansion was gained more parallel. The expansion obtained showed reduced dental side effects, as tip and torque values haven't changed in a statistically significant way.