Rapid palatal expansion for spontaneous Class II correction.

INTRODUCTION: Palatal expanders have been advocated for spontaneous correction of some Class II malocclusions. However, little research has been done to determine whether correction or improvement actually occurs with expansion. Past research has not shown whether an anterior functional shift is achieved in patients who have Class II improvement. The objective of this study was to determine whether maxillary expansion causes spontaneous correction or improvement of a Class II malocclusion. METHODS: This was a retrospective study of subjects from an orthodontic office in which models are mounted (articulator) in centric occlusion and maximum intercuspation before and after treatment. The sample included Class II patients (n = 13; mean age, 10 years 3 months) who, during the preceding 2 years, had been treated with expansion alone. Study models made before and after expansion were measured to compare the centric occlusion to the maximum intersuspation position. Condyle position indicator paper was also used to determine whether there was a functional shift after expansion. RESULTS: The only measurements with statistically significant changes from pretreatment to postexpansion were the maxillary intermolar widths. Seven of the 13 patients showed Class II improvement, but none had an anterior functional shift after expansion. CONCLUSIONS: Maxillary expansion does not predictably improve Class II dental relationships.

Assessing the American Board of Orthodontics objective grading system: digital vs plaster dental casts.

INTRODUCTION: The purposes of this study were to determine whether the American Board of Orthodontics objective grading system (ABO OGS) can be assessed accurately from digital dental casts and whether there are statistical differences between digital and plaster dental casts in scoring the ABO OGS. METHODS: Thirty posttreatment plaster dental casts were selected and scanned by OrthoCAD (Cadent, Carlstadt, NJ) to produce 30 corresponding digital dental casts. The plaster and digital casts were compared by using the criteria of the ABO OGS. Because the data were ordinal, a nonparametic statistical analysis was used. RESULTS: The Wilcoxon test for paired samples showed significant differences between the plaster and digital casts for occlusal contacts, occlusal relationships, and total scores (P <.05). No significant differences were found for alignment, marginal ridges, overjet, and interproximal contacts. Buccolingual inclination was not included in this study because of inability to perform proper measurements with the OrthoCAD program. Mean differences of points deducted ranged from .03 point for marginal ridges to 5.07 points for the total score. The variable with the most points deducted related to occlusal relationships, and the fewest points were deducted for interproximal contacts. CONCLUSIONS: Based on this study, the current OrthoCAD program (version 2.2) was not adequate for scoring all parameters as required by the ABO OGS.

The effectiveness and long-term stability of overbite correction with incisor intrusion mechanics.

BACKGROUND: Correction of deep overbite with subsequent achievement of long-term stability is difficult. The purpose of this study was to investigate the effectiveness and long-term stability of overbite correction with incisor intrusion mechanics. METHODS: The treated group consisted of 25 subjects (13 female, 12 male) with deep overbite of at least 4 mm (mean overbite, 5.9 mm). The orthodontic treatment was initiated in the late mixed or early permanent dentition, and all patients were treated nonextraction. All patients had lateral cephalometric radiographs taken at pretreatment (T1), posttreatment (T2), and postretention (T3). The treatment included cervical headgear and lever arches to intrude mainly the maxillary incisors and occasionally the mandibular incisors. Premolars were not included in the fixed appliances during the treatment. The untreated group consisted of 25 age- and sex-matched subjects from the Bolton Growth Study. RESULTS: The mechanics used were effective in overbite correction. During the posttreatment period, overbite increased by 0.7 mm. CONCLUSIONS: Although this change was statistically significant, the amount was small and is considered clinically insignificant, given the severity of the overbite pretreatment. Furthermore, a net overbite correction (T3-T1) of 3.3 mm and postretention overbite on 2.6 mm is an excellent clinical outcome.

Effects of orthodontic treatment on mandibular rotation and displacement in Angle Class II division 1 malocclusions.

The aim of this retrospective cephalometric study was to investigate the effects of orthodontic treatment on rotation and displacement of the mandible in Angle Class II, division 1 malocclusions. Thirty patients in the treated group (15 boys and 15 girls; mean age at pretreatment, 12.27 +/- 1.36 years) were compared with 28 subjects who had untreated Class II, division 1 malocclusions (15 boys and 13 girls; mean age at T1, 12.01 +/- 0.07 years). The patients in the first group were treated nonsurgically, without extraction, and without the use of functional appliances. Cephalometric data were obtained from three lateral cephalograms per case representing pretreatment (T1), posttreatment (T2), and at least 2-years postretention (T3). Thirty-seven variables were measured representing craniofacial morphology, tooth measurements, and mandibular displacement. Some variables were obtained from cranial base, maxillary, or mandibular superimposition. Statistical significance was established at P < .05, P < .01, and P < .001. The findings indicated that orthodontic treatment of Class II, division 1 malocclusions induced a more vertical mandibular growth direction associated with an increased vertical displacement of pogonion. Occlusal or vertical movement of maxillary and mandibular molars was not correlated to mandibular rotation or horizontal displacement of pogonion. When compared with controls, the treated group did not exhibit a significant difference in mandibular rotation or occlusal movement of maxillary molars; however, it did show a greater occlusal movement of mandibular molars during treatment.

Treatment outcome in a graduate orthodontic clinic using the American Board of Orthodontics grading system.

Since 1999, the American Board of Orthodontics (ABO) has used the objective grading system (OGS) to grade clinical case reports; the ABO also encourages prospective candidates to use the system. Ninety-two cases that satisfied the specifications of 6 of the ABO's malocclusion categories were selected from the files of 500 consecutively completed patients in the graduate orthodontic clinic at the University of Illinois at Chicago; this was called the university group. A comparison group of 32 cases previously presented to the ABO was collected from 5 clinicians in the Chicago area who had passed the ABO examination and become board-certified between 1984 and 2000; this was called the ABO group. Fourteen of the 32 cases in the ABO group were presented to the ABO after implementation of the OGS; these were also analyzed separately. Overall, the ABO group lost fewer points (had lower OGS scores) than did the university group (P <.05); the ABO group comprised a highly selected sample. The university group had significantly (P <.05) better scores for root parallelism, whereas the ABO group had significantly better scores for occlusal contacts and overjet scores, possibly reflecting settling after appliance removal. Finishing in the anterior segment and the second molar region was better in the ABO group. Orthodontists are good at correcting spaces in the arch and are deficient in placing adequate torque in the buccal segments. No differences were found in OGS scores among the 6 malocclusion categories. This study suggests how university cases could be completed to a higher level of quality and how other samples could be evaluated to raise the level of orthodontic treatment outcome.