Three dimensional evaluation of alveolar bone changes in response to different rapid palatal expansion activation rates

Abstract

Introduction: The aim of this multi-center retrospective study was to quantify the changes in alveolar bone height and thickness after using two different rapid palatal expansion (RPE) activation protocols, and to determine whether a more rapid rate of expansion is likely to cause more adverse effects, such as alveolar tipping, dental tipping, fenestration and dehiscence of anchorage teeth. Methods: The sample consisted of pre- and post-expansion records from 40 subjects (age 8-15 years) who underwent RPE using a 4-banded Hyrax appliance as part of their orthodontic treatment to correct posterior buccal crossbites. Subjects were divided into two groups according to their RPE activation rates (0.5 mm/day and 0.8 mm/day; n = 20 each group). Three-dimensional images for all included subjects were evaluated using Dolphin Imaging Software 11.7 Premium. Maxillary base width, buccal and palatal cortical bone thickness, alveolar bone height, and root angulation and length were measured. Significance of the changes in the measurements was evaluated using Wilcoxon signed-rank test and comparisons between groups were done using ANOVA. Significance was defined at p ≤ 0.05.Results: RPE activation rates of 0.5 mm per day (Group 1) and 0.8 mm per day (Group 2) caused significant increase in arch width following treatment; however, Group 2 showed greater increases compared to Group 1 (p < 0.01). Buccal alveolar height and width decreased significantly in both groups. Both treatment protocols resulted in significant increases in buccal-lingual angulation of teeth; however, Group 2 showed greater increases compared to Group 1 (p < 0.01).Conclusion: Both activation rates are associated with significant increase in intra-arch widths. However, 0.8 mm/day resulted in greater increases. The 0.8 mm/day activation rate also resulted in more increased dental tipping and decreased buccal alveolar bone thickness over 0.5 mm/day.

Differential assessment of skeletal, alveolar, and dental components induced by microimplant-supported midfacial skeletal expander (MSE), utilizing novel angular measurements from the fulcrum

“…It has been believed that, by young adulthood, fusion of the sutures virtually eliminates the potential for sutural separation without surgical assistance [ 34 ]. Even in growing patients, heavy forces of RME produce an increased buccal inclination of anchored teeth at the end of the active phase, regardless of the type of expanders [ 3 , 4 , 10 , 35 – 38 ] or of the rate of activation [ 8 ]. Also in pre-pubertal patients, it has been demonstrated that alveolar structures splayed buccally and carried the teeth with them [ 3 , 37 ], and that a 6-month period is necessary to allow recovery of the alveolar plate [ 39 ].…”

“…However, a significant alveolar bone bending and dental tipping cannot be ignored, even in these young populations. Dentoalveolar changes are associated with a decrease in alveolar bone height, fenestration, and bone dehiscence [ 8 ]. These negative effects escalate in mature patients because of the difficulty in splitting the heavily interlocked midpalatal suture with tooth-borne appliance.…”

Influence of Hyrax screw position on dental movement and cortical bone: A study of finite elements

“…Several authors (3,20) found that the amount of maxillary expansion is positively correlated with the magnitude of the buccal inclination of the crowns of the anchorage teeth of the expansion device. These findings are consistent with the results obtained in the present study where a greater expansion was observed due to the buccal inclination with a screw configuration below the center of resistance of the posterior teeth (observed in the anterior-low, medium-low and posterior-low positions).…”

Sutural loading in bone‐ versus dental‐borne rapid palatal expansion: An ex vivo study

“…In the DRPE, expansion force is applied through the teeth, and some of the expansion force will be dissipated by the PDL and through dental tipping. [5][6][7][8][9]16 This explains the excessive strains recorded at the alveolar bone and the delayed MPS opening in the DRPE. Additionally, the attachment points of the expander and the anchor teeth are vertically and laterally farther from the MPS, which will potentially result in less efficient mechanical loading of the suture.…”

“…side effects, including tipping of the anchor teeth and alveolar bone, possible dehiscence, and long-term instability. [5][6][7][8][9] Maxillary expansion is dependent on the maturation status of the intermaxillary suture. 10 As patient age, the suture increases in complexity and eventually fuses.…”