Counterclockwise Rotation Of Occlusal Plane Research Articles

Late Maxillary Protraction in Patients with Unilateral Cleft Lip and Palate: A Retrospective Study

This retrospective study assessed the dentoskeletal effect of late maxillary protraction (LMP; reverse-pull headgear, Class III elastics, and maxillary sutural loosening) in unilateral cleft lip and palate (UCLP) patients versus a control group of untreated UCLP patients. Cephalograms taken at age 13 to 14 years (T1) and 17 to 18 years (T2) were used for this study. The study group comprised 18 patients (10 male and 8 female, mean age at start of LMP therapy = 13.4 [0.45] years). A control groups of 17 patients (8 male and 9 female, mean age = 13.5 [0.44] years) was used for comparison. The repeated-measures analysis of variance showed statistically significant changes across time between groups for the following variables (mean difference [T2-T1] in the study group, 95% confidence interval): SNA (°) (1.95, 0.75 to 3.15), A ⊥ Na Perp (mm) (1.82, 0.86 to 2.77), CoA (mm) (2.92, 1.53 to 4.31), ANB (°) (3.13, 2.02 to 4.24), Wits (mm) (7.82, 5.01 to 10.54), Mx-Md Diff (mm) (0.62, -1.58 to 2.83), Occl P-SN (°) (-3.98, -5.99 to -1.98), overjet (mm) (8.82, 5.90 to 11.74), FMIA (°) (4.05, -0.05 to 8.15), and IMPA (°) (-5.77, -9.74 to -1.80). Late maxillary protraction created a slight open bite (0.66 mm). Trends for overeruption of mandibular incisors and an increase in lower face height (P = .07 for both) were noted in the study group. Late maxillary protraction produced a combination of skeletal changes (protraction of maxilla, improvement in the maxillo-mandibular skeletal relationship) and dental compensations (counterclockwise rotation of occlusal plane, retroclination of mandibular incisors) in patients with UCLP. Late maxillary protraction was also associated with some unwanted tooth movements (open bite tendency, mandibular incisors overeruption).

TMJ disc displacement as a cause of changes in facial skeletal morphology

To evaluate an efficiency of TMJ open disc repositioning surgery with use of bone anchors. TMJ open disc repositioning surgery was indicated for patients with TMJ anterior disc displacement without reduction and skeletal class II or asymmetric forms of dysgnathia related to condyle resorption. Surgery was performed on 9 patients divided into two groups: the first one (5 patients) consisted of patients that were seeking help for bite problems, the second one (4 patients) consisted of patients with signs of TMJD, such as decreased mouth opening and pain in TMJ area. The first group patients underwent open disc repositioning and orthognathic surgery with counterclockwise rotation of occlusal plane. All the patients showed stability in skeletal and occlusal elements at 6 months follow-up period. The second group patients underwent disc-repositioning surgery only. In all the cases pain was completely eliminated but there was no sufficient improvement in MIO at 6 months follow-up period. Open TMJ disc repositioning surgery can be used for prevention of relapse after orthognathic surgery in patients with TMJ internal derangements such as anterior disc displacement without reduction.

骨格性下顎前突症の治療による顎顔面形態および歯・歯槽性の形態変化 外科的矯正治療症例と歯科矯正治療単独症例との比較

The purpose of this study was to compare the skeletal and dentoalveolar changes in skeletal class III patients who underwent only orthodontic treatment, with those in patients who received both orthodontic treatment and orthognathic surgery, and to identify a critical point in the treatment of skeletal class III malocclusion. Fifteen skeletal class III patients who underwent both orthodontic treatment and orthognathic surgery (mean age, 18.4 years; the surgical group), and 14 skeletal class III patients who underwent only orthodontic treatment (mean age, 18.1 years; the orthodontic group), were included in this study. They were treated by the multi-bracket edgewise technique without premolar extraction. Angular and linear cephalometric variables were measured, using lateral cephalograms, for each patient, taken before and at the end of the active orthodontic treatment. Unpaired and paired t-tests were used for statistical analysis. Before treatment, there were no significant differences in any of the cephalometric variables between the surgical and orthodontic groups, except for overjet. Significant changes commonly observed in both groups were a decrease in SNB, an increase in ANB, clockwise rotation of the mandible, counterclockwise rotation of the occlusal plane, and an increase in overjet. On the other hand, a significant increase in U1-FH, and a significant decrease in Ll-Mand. were found only in the orthodontic group. With regard to the extent of the change during treatment, the changes in SNB, ANB, Wits appraisal, and overjet were significantly greater in the surgical group than in the orthodontic group, whereas the changes in U1-FH and the functional occlusal plane angle were significantly greater in the orthodontic group than in the surgical group. Moreover, significant differences were also seen inL1-Mand. and overbite. These results suggest that counterclockwise rotation of the functional occlusal plane is the critical change in the orthodontic treatment of skeletal class III patients without orthognathic surgery, in addition to conventional skeletal and dentoalveolar changes, such as in the anteroposterior jaw relationship and the inclination of anterior teeth.