Difference in the Alveolar Bone Remodeling Between the Adolescents and Adults During Upper Incisor Retraction: a Retrospective Study

Background: The purpose of this study was to compare the difference of alveolar bone remodeling between the adolescents and adults in the maxillary incisor area during retraction. Methods: This retrospective study included 72 female patients who needed moderate anchorage to correct the bimaxillary protrusion. Subjects were further divided into the minor group (n=36, 11-16 years old) and adult group (n=36, 18-35 years old). Digital lateral cephalography and cone beam CT scanning were taken in each patient before (T0) and after treatment (T1). Cephalometry was conducted to assess incisor retraction, while alveolar bone thickness (ABT), alveolar bone distance (ABD, and alveolar bone area (ABA) were detected to assess changes in the alveolar bone. Results: No difference in the inclination of upper incisors was observed at both T0 and T1. Changes in the alveolar bone showed a similar tendency with bone apposition on the labial side and resorption on the palatal side. Less increase in the labial ABT (T1-T0) and more decrease in the palatal ABT (T1-T0) was found in the adult group, leading to less total ABT in the adult group. Higher reduction inn ABD (T1-T0) was found in the adult group. Moreover, more decrease in the ABA (T1-T0) was found in the adult group. Conclusion: When compared adolescents, adult patients have less alveolar bone support after orthodontic treatment, showing a through-the-bone remodeling pattern. Orthodontic should take the age into consideration to reduce the potential periodontal risks during treatment planning.

Morphological changes of the anterior alveolar bone due to retraction of anterior teeth: a retrospective study

Backgroud To analyze the morphological changes of the anterior alveolar bone after the retraction of incisors in premolar extraction cases and the relationship between incisor retraction and remodeling of the alveolar base represented by points A and B displacements. Methods Pre- (T0) and post-treatment (T1) lateral cephalograms of 308 subjects in the maxilla and 154 subjects in the mandible who underwent the orthodontic treatment with extraction of 2 premolars in upper or lower arches were included. Alveolar bone width and height in both the maxillary and mandible incisor area were measured at T0 and T1 respectively. By superimposing the T0 and T1 cephalometric tracings, changes of points A and B, and the movement of the incisors were also measured. Then the correlation between incisor movement and the displacements of points A and B was analyzed. Results The alveolar bone width (ABW) showed a significant decrease in both maxilla and mandible (P < 0.001) except the labial side of the mandible (P > 0.05). The alveolar bone height (ABH) showed a significant increase in the labial side of maxilla and a significant decrease in the lingual side of maxilla and mandible. A strong positive correlation was verified between incisor movement and position changes of points A and B in both horizontal and vertical directions. Conclusions Anterior alveolar bone width and height generally decreased after orthodontic treatment. Incisor retraction led to significant position changes of points A and B. The decrease of anterior alveolar bone due to significant incisor retraction should be taken into account in treatment planning.

The effect of platelet-rich fibrin (PRF) on maxillary incisor retraction rate

ABSTRACT Objective To investigate the efficiency of platelet-rich fibrin (PRF) injection on maxillary incisor retraction rate. Materials and Methods The study included 40 patients (23 women and 17 men; mean age; 20.7 ± 1.45) with Class II Division 1 malocclusion. The treatment plan for all patients was extraction of the maxillary first premolars and canine distalization, followed by retraction of the maxillary incisors. Patients were randomly divided into two groups. The study group received injectable platelet-rich fibrin (i-PRF) two times with an interval of 2 weeks; the control group did not receive i-PRF. In both groups, the measurements were bilaterally assessed as the distances between the lateral and canine teeth on the plaster models at five time points. The rate of incisor movement was evaluated by Student's t-test, analysis of variance, and Tukey honestly significant difference tests. Statistical significance was set as P &lt; .05. Results The average movements of incisors were significantly higher in the study group than the control group at all time points (P &lt; .05). According to the within-group comparison, none of the measurements showed any significant differences between the right and left sides in both groups at all time points (P &gt; .05). While the movement of incisors was significantly higher in the study group in the week following the PRF injection compared to the other weeks (P &lt; .05), there were no significant differences in the control group at all-time points (P &gt; .05). Conclusions Applying i-PRF significantly increased the rate of maxillary incisor retraction at all time intervals. Platelet-rich fibrin injection can be an effective method for shortening treatment duration.

Alveolar bone response to maxillary incisor retraction using stable skeletal structures as a reference

ABSTRACT Objectives To evaluate alveolar bone change in relation to root position change after maxillary incisor retraction via cone-beam computed tomography (CBCT) using stable skeletal structures as a reference. Materials and Methods A total of 17 subjects (age 24.7 ± 4.4 years) who required retraction of the maxillary incisors were included. Labial and palatal alveolar bone changes and root change were assessed from preretraction and 3 months postretraction CBCT images. The reference planes were based on stable skeletal structures. The Kruskal-Wallis test and Wilcoxon signed-rank test were used to compare changes within and between groups, as appropriate. Spearman rank correlations were used to identify the parameters that correlated with alveolar bone change. The significance level was set at .05. Results The labial alveolar bone change after maxillary incisor retraction was statistically significant (P &lt; .05), and the bone remodeling/tooth movement (B/T) ratio was 1:1. However, the palatal bone remained unchanged (P &gt; .05). The change in inclination was significantly related to labial alveolar bone change. Conclusions Using stable skeletal structures as a reference, the change in labial alveolar bone followed tooth movement in an almost 1:1 B/T ratio. Palatal alveolar bone did not remodel following maxillary incisor retraction. The change in inclination was associated with alveolar bone change.

Von Mises stresses on Mushroom-loop archwires for incisor retraction: a numerical study

ABSTRACT Objective: To perform a numerical simulation using FEM to study the von Mises stresses on Mushroom archwires. Methods: Mushroom archwires made of titanium-molybdenum alloy with 0.017 x 0.025-in cross-section were used in this study. A YS of 1240 MPa and a Young’s modulus of 69 GPa were adopted. The archwire was modeled in Autodesk Inventor software and its behavior was simulated using the finite element code Ansys Workbench (Swanson Analysis Systems, Houston, Pennsylvania, USA). A large displacement simulation was used for non-linear analysis. The archwires were deformed in their extremities with 0° and 45°, and activated by their vertical extremities separated at 4.0 or 5.0 mm. Results: Tensions revealed a maximum of 1158 MPa at the whole part of the loop at 5.0mm of activation, except in a very small area situated at the top of the loop, in which a maximum of 1324 Mpa was found. Conclusions: Mushroom loops are capable to produce tension levels in an elastic range and could be safely activated up to 5.0mm.

Alveolar bone modeling and bone modeling/ tooth movement ratio during mandibular incisor retraction: a retrospective study

Background: The objective of this study was to explore the limit of orthodontic tooth movement by evaluating changes of alveolar bone during mandibular incisor retraction and comparing the bone modeling/tooth movement (B/T) ratio among patients with different vertical facial types. Methods: There were 103 patients with bimaxillary dentoalveolar protrusion evaluated with cephalograms in this study. The alveolar bone thickness (ABT) and cortical plate remodeling at cervical level (S1), middle level (S2) and apical level (S3) in Tip and Torque groups were measured, and B/T ratio in patients with different vertical facial types was calculated. Results: After excluding growth effect, buccolingual ABT at S1 and S2, as well as labial ABT at S1 in both Tip and Torque group decreased significantly. Cortical plate at three levels in Torque group remodeled to the lingual side. But in Tip group, cortical plate at S1 remodeled to the lingual side and cortical plate at S2 and S3 remodeled to the labial side. Regarding the B/T ratio, high-angle patients was smaller than average-angle and low-angle patients. Conclusions: In conclusion, resorption of alveolar bone was more than apposition during mandibular incisor retraction. The direction of alveolar cortical modeling was as same as tooth movement and the modeling amount was proportional to the distance of tooth movement. In addition, the B/T ratio was different among patients with different vertical craniofacial patterns. Close attention should be paid to high-angle patients with narrower ABT and smaller B/T ratio. Keywords: alveolar bone modeling, orthodontic tooth movement limit, incisor retraction, vertical facial patterns

Class II Division 1 malocclusion treatment using TADs: Case report

Introduction. Orthodontic treatment of Class II Division 1 (II/1) malocclusions in adults can be challenging since skeletal effects are limited. Possible treatment options are orthodontic camouflage or orthognatic surgery, in severe cases. The aim of this paper was to present a successful management of Class II malocclusion in an adult patient using temporary anchorage devices (TADs). Case report. After detailed clinical examination, study models and cephalometric analysis, a 26 years old patient was diagnosed with Class II malocclusion, an overjet of 12 mm, congenitally missing tooth 41 and midline shifted to the right in upper dental arch. In prior orthodontic treatment, patient had upper premolars extracted. Posterior teeth in upper left quadrant were shifted mesially. The camouflage treatment was considered, using temporary anchorage devices (TADs) to distalize posterior teeth on the left side, and gain space for incisor retraction and midline correction in upper dental arch. Results. Using TADs as additional anchorage in anterior region and coil spring for molar distalization, the space was made for tooth 23, midline correction and incisor retraction. After 40 months, a satisfactory result was achieved, overjet and midline correction, class I canines occlusion and class II molar occlusion. Conclusion. Class II/1 malocclusion in adults can be successfully treated using TADs. The success depends on the severity of malocclusion and patient cooperation.