Accuracy of the digital workflow for guided insertion of orthodontic palatal TADs: a step-by-step 3D analysis.

BACKGROUND: The introduction in the orthodontic field of the digital workflow for guided insertion of palatal TADs and the development of the 1-visit protocol led to the reduction of chair time and the possibility of complete customization of designs and materials. Conversely, the reduction of operative steps implicates a lower tolerance of deviations between the planned and the actual position of the miniscrews, particularly when the orthodontic device is fixed on 4 palatal TADs or has a rigid structure. This study aims to analyze the influence of each step of the digital workflow on the deviation of the miniscrews' axis of insertion in a bicortical sample. The null hypothesis is that there are no significant differences in the deviations among the operative steps. METHODS: 33 subjects were selected for insertion of bicortical palatal miniscrews with a 1-visit protocol. Digital files were collected at the three stages of the workflow (i.e., digital planning, laboratory prototype, post-insertion impression). A 3D software analysis was performed on a total of 64 miniscrews. After automatic shape recognition of the guiding holes of the digital plan and the scanbodies of the laboratory prototype and post-insertion impression as geometric cylinders, their three-dimensional longitudinal axis was traced and the deviation among them was calculated. Friedman test with Bonferroni correction was performed to assess the significance of the deviations among the three steps, with significance set at p < 0.05. RESULTS: The laboratory step has a significantly lower degree of deviations (2.12° ± 1.62) than both the clinical step (6.23° ± 3.75) and the total deviations (5.70° ± 3.42). No significant differences were found between miniscrews inserted on the left or the right side. CONCLUSIONS: This study suggests that laboratory procedures such as surgical guide production or rapid prototyping don't play a significant role in the degree of deviations between the planned and the positioned palatal TADs. Conversely, the clinical steps have a bigger influence and need to be carefully evaluated. Despite this difference, there is a cumulative effect of deviations that can lead to the failure of the 1-visit protocol.

Skeletal expansion using a miniscrew-assisted rapid palatal expansion in a 50-year-old patient.

This case report illustrates a nonsurgical treatment plan using a miniscrew-assisted rapid palatal expander (MARPE) in a 50-year-old patient with maxillary transverse deficiency. The MARPE appliance consisted of a conventional Hyrax expander anchored to 4 orthodontic miniscrews. The exact locations of the miniscrews were determined with virtual planning software. Cone-beam computed tomography (CBCT) scans were superimposed on the maxillary digital model, and 3-dimensional-printed surgical guides were used to accurately position the mini-implants. A slow expansion protocol was used, and the appliance was held in place during the entire treatment (almost 20 months). Pretreatment, postexpansion, and posttreatment CBCT scans show the parallel expansion obtained without dental torque compensation or bite opening. The posttreatment scan showed that a long period is required to complete the midpalatal suture mineralization. MARPE has proven effective in correcting transverse discrepancies, even in adults. However, posttreatment CBCT imaging showed incomplete ossification of the midpalatal suture, demonstrating that the retention period should be extended in some adult patients.

Sagittal and Vertical Craniofacial Growth Pattern and Timing of Circumpubertal Skeletal Maturation: A Multiple Regression Study.

The knowledge of the associations between the timing of skeletal maturation and craniofacial growth is of primary importance when planning a functional treatment for most of the skeletal malocclusions. This cross-sectional study was thus aimed at evaluating whether sagittal and vertical craniofacial growth has an association with the timing of circumpubertal skeletal maturation. A total of 320 subjects (160 females and 160 males) were included in the study (mean age, 12.3 ± 1.7 years; range, 7.6-16.7 years). These subjects were equally distributed in the circumpubertal cervical vertebral maturation (CVM) stages 2 to 5. Each CVM stage group also had equal number of females and males. Multiple regression models were run for each CVM stage group to assess the significance of the association of cephalometric parameters (ANB, SN/MP, and NSBa angles) with age of attainment of the corresponding CVM stage (in months). Significant associations were seen only for stage 3, where the SN/MP angle was negatively associated with age (ß coefficient, -0.7). These results show that hyperdivergent and hypodivergent subjects may have an anticipated and delayed attainment of the pubertal CVM stage 3, respectively. However, such association remains of little entity and it would become clinically relevant only in extreme cases.