Objective: To test the null hypothesis that circumaxillary sutures do not show bony displacement in response to rapid maxillary expansion (RME) therapy. Materials and Methods: Subjects consisted of eight growing patients (two male and six female) with Angle Class I malocclusion, bilateral posterior crossbite, transverse maxillary deficiency, deep palatal vault, and dental crowding at the start of the treatment. A Hyrax palatal expander was used for each patient, and activation protocol required the screw to be turned three times per day (0.25 mm per turn) for an average of 18 days for all subjects. Multislice computed tomography (CT) scans were performed before rapid palatal expansion (time T0) and again at the end of the active expansion phase (time T1) without removing the expander. Measurements were carried out directly on the CT image using the OsiriX Imaging software program. Data were analyzed statistically by using the Wilcoxon signed rank test. Results: All linear measurements showed an increase between T0 and T1 and RME determined a widening of suture; however, sutures far from the maxilla showed a smaller degree of disarticulation. Conclusions: The hypothesis is rejected. Early treatment with RME produced a significant bony displacement by circumaxillary suture opening. The amount of changes of sutures depends on different factors relating to the subjects and varies between different sutures, showing that sutures that articulate directly with the maxilla face a greater influence by the RME compared with those located further away. (Angle Orthod. 2011;81:36-41.)

Objective: To test the null hypothesis that the spheno-occipital synchondrosis does not show bony displacement in response to rapid maxillary expansion (RME) therapy in youngsters. Materials and Methods: A total of 16 computed tomography (CT) records were taken from 8 growing patients (2 males and 6 females), before (T0) and after (T1) treatment with RME. All patients had been diagnosed originally with transverse maxillary deficiency. The mean chronological age of the patients was 9.8 Ϯ 1.8 years (range, 8 to 11.4 years). High-resolution multislice multidetector CT was used to study quantitatively the extent of the opening of the spheno-occipital synchondrosis following RME. A low-dose CT scan protocol was used (80 kV, 10 mA) and the data file of each patient was transferred to a workstation where the anteroposterior width of the spheno-occipital synchondrosis was measured on axial images. Results: Before treatment with RME (T0), the anteroposterior mean width of the spheno-occipital synchondrosis was 1.73 Ϯ 0.46 mm immediately after the active phase of expansion (T1), and the width of the synchondrosis increased to 2.30 Ϯ 0.47. This difference was statistically significant according to the Wilcoxon signed rank test (P Ͻ .05). Conclusion: Rapid maxillary expansion leads to a small immediate widening of the sphenooccipital synchondrosis in youngsters. (Angle Orthod. 2010;80:106-110.)

The purpose of this study was to evaluate the dimensional changes of the alveolar ridge in patients with congenitally missing maxillary lateral incisors. The width and height of the alveolar ridge were compared before and after opening space for an endosseous dental implant between the central incisor and canine. Pre- and post-treatment dental stone models of 31 patients (8 males, 23 females; mean age 15.1 ± 7.9 years pre-treatment, 17.6 ± 8 years post-treatment) with unilaterally or bilaterally, congenitally missing maxillary lateral incisors were used in this study. Pre- and post-treatment measurements included: the space between the maxillary central incisor and canine, the depth of the labial concavity, and the width and height of the lateral incisor alveolar ridge. Two different techniques were used to measure the ridge width. Student's paired samples t-test was used to test for significance. The alveolar ridge underwent statistically significant width loss (Method 1: 4-8 per cent, Method 2: 13-15 per cent) during the course of orthodontic treatment. A 6-12 per cent loss in ridge height was also noted. The depth of the labial concavity between the maxillary central incisor and canine nearly doubled. There was a significant decrease in the width and height of the alveolar ridge in patients congenitally missing a maxillary lateral incisor who received orthodontic treatment to create space for an endosseous dental implant.

Structured AbstractObjectives: To evaluate the amount of external apical root resorption (EARR) secondary to orthodontic treatment in patients with Short Root Anomaly (SRA) compared to patients with average root lengths using Cone Beam Computed Tomography (CBCT). Settings and Sample Population:Cone beam computed tomography scans of 23 SRA and 26 control patients were selected from 232 pretreatment scans from a single private practice. Materials and Methods:Cone beam computed tomography scans before (T1) and after orthodontic treatment (T2) were evaluated for differences in the change in tooth and root length of the maxillary incisors between both groups. Gender, treatment duration and age were examined as covariates. Results:The mean values for root and tooth length of the maxillary incisors decreased by a range of 0.6 to 1.3 mm after orthodontic treatment. There was no significant difference between the groups for the majority of the measurements although there was a trend for less EARR in the SRA group. The maxillary left central incisor had significantly less proportional and non-proportional loss in tooth length in the SRA group. Age, gender and treatment duration were not associated with change in the proportional and non-proportional lengths for both groups. Conclusion:Patients with SRA did not exhibit a significant difference in the proportional and non-proportional change of length after orthodontic treatment when compared to the controls for most measurements. Only tooth length for the maxillary left central incisor had significantly less reduction after orthodontic treatment for both the proportional and non-proportional measurements in the SRA group compared to the control group. K E Y W O R D Sapical root resorption, cone beam computed tomography, Short Root Anomaly | 33 CUTRERA ET Al.