Mode of correction is related to treatment timing in Class II patients treated with the mandibular advancement locking unit (MALU) appliance.

OBJECTIVE: To investigate the proportion of skeletal/dentoalveolar components for correction of Class II malocclusion in relation to the pubertal growth peak (PGP) among patients treated with the mandibular advancement locking unit (MALU) appliance. MATERIALS AND METHODS: We conducted a retrospective study of 27 orthodontic patients (age range: 12-18 years; mean age 14.9 years) with skeletal Class II Division 1 malocclusion who were treated with the MALU appliance until they reached Class I occlusion with overjet and overbite within normal range. Pretreatment (T1) and posttreatment (T2) lateral cephalograms were analyzed using standard cephalometrics and sagittal occlusion analysis to assess changes in the dentoalveolar and skeletal complex. The cervical vertebral maturation (CVM) method was used to determine participants' skeletal maturation in T1 cephalograms. Based on this maturation, participants were divided into two groups: the peak group (treatment initiation before or during PGP [peak group, n=15]) or the postpeak group (treatment initiation after the PGP [n = 12]). RESULTS: No significant differences between groups were found at T1 for most of the skeletal and dental parameters investigated. At T2, the mean ANB angle and proclination of the mandibular incisors were significantly smaller in the peak group than in the postpeak group. In the peak group, skeletal correction comprised 54% and dental correction 46% of the total change at T2, while in the postpeak group the corresponding figures were 24% and 76%, respectively. CONCLUSIONS: Treatment initiated before or during PGP seems to result in a more favorable SNA/SNB relationship and less tipping of the mandibular incisors than when treatment is initiated after PGP.

Digital volume tomography in the diagnosis of periodontal defects: an in vitro study on native pig and human mandibles.

BACKGROUND: The aim of this study of native pig and human mandibles was to investigate the accuracy and quality of the representation of periodontal defects by intraoral radiography (IR), panoramic radiography (PR), computed tomography (CT), and digital volume tomography (DVT) in comparison with histologic specimens. METHODS: Following the standardized preparation of periodontal defects (14 dehiscences, fenestrations, 2- to 3-walled intrabony defects, respectively; Class I, II, and III furcation involvement) in six pig and seven human mandibles, IR, PR, CT, and DVT were performed. The histologic specimens were produced by cutting blocks with the individual defects out of the mandibles, embedding them in acrylic, and producing sagittal and axial microsections. The intrabony defects were measured using appropriate software on the digitized IR and PR images programs. The histologic sections were measured by reflecting stereomicroscopy. The statistical comparison between the measurements of the radiographic images and those of the histologic specimens was performed with Pearson's correlation coefficient. The quality of the radiographic images was determined through the subjective perception and detectability of the intrabony defects by five independent observers. RESULTS: All intrabony defects could be measured in three planes in the CT and DVT scans. Comparison with the histologic specimens yielded a mean deviation of 0.16 +/- 0.10 mm for the CT scans and 0.19 +/- 0.11 mm for the DVT scans. On the IR and PR images, the defects could be detected only in the mesio-distal and craniocaudal planes. In comparison with the histologic specimens, the IR images revealed a mean deviation of 0.33 +/- 0.18 mm and the PR images a mean deviation of 1.07 +/- 0.62 mm. The quality rating of the radiographic images was highest for the DVT scans. CONCLUSIONS: Overall, the CT and DVT scans displayed only a slight deviation in the extent of the periodontal defects in comparison with the histologic specimens. Both radiographic imaging techniques permitted imaging of anatomic osseous structures in three planes, true to scale, and without overlay or distortion. The DVT scans showed the best imaging quality.