Thomas Razmus

Class III camouflage treatment: What are the limits?

INTRODUCTION The purpose of this study was to determine the skeletal, dental, and soft-tissue changes in response to camouflage Class III treatment. METHODS Thirty patients (average age, 12.4 + or - 1.0 years) with skeletal Class III malocclusions who completed comprehensive nonextraction orthodontic treatment were studied. Skeletal, dental, and soft-tissue changes were determined by using published cephalometric analyses. The quality of orthodontic treatment was standardized by registering the peer assessment rating index on the pretreatment and posttreatment study models. The change in the level of gingival attachment with treatment was determined on the study casts. The results were compared with a group of untreated subjects. Data were analyzed with repeated measures analysis and paired t tests. RESULTS The average change in the Wits appraisal was greater in the treated group (1.2 + or - 0.1 mm) than in the control group (-0.5 + or - 0.3 mm). The average peer assessment rating index score improved from 33.5 to 4.1. No significant differences were found for the level of gingival attachments between the treatment and control groups. The sagittal jaw relationship (ANB angle) did not improve with camouflage treatment. A wide range of tooth movements compensated for the skeletal changes in both groups. The upper and lower limits for incisal movement to compensate for Class III skeletal changes were 120 degrees to the sella-nasion line and 80 degrees to the mandibular plane, respectively. Greater increases in the angle of convexity were found in the treated group, indicating improved facial profiles. Greater increases in length of the upper lip were found in the treated group, corresponding to the changes in the hard tissues with treatment. CONCLUSIONS Significant dental and soft-tissue changes can be expected in young Class III patients treated with camouflage orthodontic tooth movement. A wide range of skeletal dysplasias can be camouflaged with tooth movement without deleterious effects to the periodontium. However, proper diagnosis and realistic treatment objectives are necessary to prevent undesirable sequelae.

Stability of Class II treatment with an edgewise crowned Herbst appliance in the early mixed dentition: Skeletal and dental changes.

INTRODUCTION The objectives of this research were to assess skeletal and dental changes in patients with Class II malocclusion treated with the edgewise crowned Herbst appliance in the early mixed dentition and to measure the stability of treatment after a second phase of fixed appliance therapy. METHODS Twenty-two patients (ages, 8.4 ± 1.0 years) with Class II Division 1 malocclusion treated consecutively with the edgewise crowned Herbst appliance in the early mixed dentition were studied. Lateral cephalograms were taken before Herbst treatment, immediately after Herbst treatment, and after a second phase of fixed appliance therapy. The results were compared with a control group of untreated Class II subjects selected from the Bolton-Brush study, matched by age, sex, and craniofacial morphology. A total of 37 sagittal, vertical, and angular cephalometric variables were evaluated. Changes in overjet and molar relationship were calculated. Changes due to growth were subtracted to obtain the net changes due to treatment. The data were analyzed by using analysis of variance (ANOVA) and the t tests. RESULTS Overcorrection with the Herbst appliance resulted in an average reduction in overjet of 7.0 mm and a change in molar relationship of 6.6 mm. Several factors contributed to the change in overjet: restraint of the forward movement of the maxilla (0.4 mm), forward movement of the mandible (2.0 mm), backward movement of the maxillary incisors (3.7 mm), and forward movement of the mandibular incisors (0.9 mm). Skeletal changes together with a 3.1-mm backward movement of the maxillary molars and a 1.1-mm forward movement of the mandibular molars contributed to the changes in molar relationship. After the second phase of fixed appliance therapy, the change in overjet was reduced to 2.8 mm. Most of the remaining overjet corrections were contributed by the restraint of maxillary growth (2.8 mm). The mandible moved posteriorly by 1.6 mm, and the mandibular incisors moved forward by 0.2 mm. Change in molar relationship was reduced to 2.2 mm. The maxillary molars moved backward by 0.2 mm, and the mandibular molars moved forward by 0.8 mm. CONCLUSIONS Overcorrection of Class II malocclusion with the edgewise crowned Herbst appliance in the early mixed dentition resulted in a significant reduction in overjet and correction of the molar relationship. A portion of the correction was maintained after a second phase of fixed appliance therapy because of the continuous restraint of maxillary growth and the dentoalveolar adaptations.

Effects of filtration, collimation, and target-receptor distance on artificial approximal enamel lesion detection with the use of RadioVisioGraphy

RadioVisioGraphy is an imaging modality that uses a charge-coupled device electronic sensor. Dental charge-coupled device imaging can be used to detect dental caries; however, it was not known what effect beam collimation, added filtration, or variable target-receptor distance has on this task. The purpose of this investigation was to study these effects were imaged by conventional radiography and RadioVisioGraphy varying exposure time, target-receptor distance, collimation, and filtration. Printed RadioVisioGraphy images without enhancement and E-speed radiographs were evaluated by five viewers. The number of true-positives and false-positives were compared as were sensitivity, specificity, positive and negative predictive values, accuracy, and entrance level radiation exposure. Added filtration reduced the false-positives regardless of collimation or target-receptor distance. True-positives and false-positives were greater at a target-receptor distance of 8 inch at exposures < 0.10 seconds (F < 0.0151). E-speed radiographs had a greater specificity and positive predictive value than RadioVisioGraphy images without image enhancement; however, no significant differences were found between RadioVisioGraphy images and E-speed radiographs in true-positive or false-positive identifications without image enhancement.

Assessment of the knowledge of graduating American dental students about the panoramic image

The objective of this study was to assess the capability of graduating dental students to identify the causes of undiagnostic panoramic images and to interpret anatomic landmarks on panoramic films. Seventeen dental schools were represented by 311 students. A radiology faculty member at each institution completed a questionnaire that addressed lecture time and experience provided to students in panoramic radiography. The faculty member administered a test instrument comprised of several panoramic radiographs that demonstrated one or more labeled anatomic structures, technical errors, or projection artifacts and multiple choice questions that addressed each entity. The mean percentage correct for the tested population on the entire test instrument was 72.9%. The mean percentage correct for questions addressing anatomy, error and artifact recognition, and error correction was 84.0%, 61.4% and 45.2%, respectively. Factors that significantly (p < 0.05) affected student performance were the number of lecture hours provided, whether or not students took panoramic radiographs of patients, and the method of student selection as participants. Laboratory or self-study projects and the number of panoramic radiographs (> or = 1) taken of patients did not significantly affect student performance on the test instrument.

Evaluation of masseter muscle morphology in different types of malocclusions using cone beam computed tomography

OBJECTIVES To evaluate the length and orientation of masseter in different types of malocclusions using Cone Beam Computed Tomography (CBCT). METHODS Samples of 180 patients seeking orthodontic treatment at the University of Nevada, Las Vegas School of Dentistry, were included in the study. Pre-treatment multi-slice CBCT scans of these patients were divided into three anteroposterior groups: Class I subjects with ANB angle 0° to 5°; Class II subjects with ANB angle >5°; and Class III subjects with ANB angle <0°. CBCT scans were also divided into three vertical groups: normodivergent subjects with mandibular plane angle 22° to 30°; hyperdivergent subjects with mandibular plane angle >30°, hypodivergent subjects with mandibular plane angle <22°. The masseter was identified and landmarks were placed on the anterior border, at the origin and insertion of the muscle in 3-D mode of the Dolphin Imaging 10.5 Premium software. The Frankfort Horizontal Plane was used as a reference plane and an angular measurement was obtained by intersection of a line produced by the masseter landmarks to calculate the orientation of the muscles. The length of the masseter was measured and data were analyzed using ANOVA and matched pairs test. RESULTS ANOVA found significant differences in muscle length among the three vertical groups for both the left and right muscles. Paired t test showed significantly shorter muscle length for the hypodivergent group (43.3 ± 4.0 mm) compared to the normodivergent group (45.6 ± 4.5 mm, P < 0.05) and shorter muscle length for the hyperdivergent group (42.3 ± 4.7 mm) compared to the hypodivergent group, P < 0.05. No significant differences were found in muscle length among the three anteroposterior groups. However, significant differences in muscle orientation angle were found among the three anteroposterior groups (P < 0.05). Class II subjects were found to have the most acute orientation angle (67.2 ± 6.6°) and Class III had the most obtuse orientation angle (81.6 ± 6.8°). CONCLUSIONS These results suggest that certain types of malocclusion may have different masseter lengths and orientations and these differences may have implications for the mechanical advantage in bite force. For example, Class III individuals may have greater bite force than Class II individuals because the muscle fibers are oriented more along the arch of closure.

Anteroposterior relationship of the maxillary central incisors to the forehead in adult white males.

AIM To evaluate and compare the anteroposterior relationship of the maxillary central incisors to the forehead in white male adults with harmonious profiles and white male adult orthodontic patients. METHODS Photographs of 101 white male adults with good facial harmony (control sample) were compared with photographs of 97 white male adults seeking orthodontic treatment (study sample). All were profile images with the maxillary central incisors and foreheads in full view. The images were imported into an image editing software program, resized, and rotated to the upright head position. Reference lines were constructed to assess the anteroposterior positions of the maxillary central incisors and forehead inclinations. RESULTS In the control sample, the maxillary central incisors were positioned between the forehead facial axis (FFA) point and glabella in 91%, posterior to the FFA point in 8%, and anterior to the glabella in <1%. The position of the maxillary central incisors was moderately correlated with forehead inclination (r² = 0.37). In the study sample, the maxillary central incisors were positioned between the FFA point and glabella in 34%, posterior to the FFA point in 59%, and anterior to the glabella in 7%. Maxillary central incisor position and forehead inclination were strongly correlated (r² = 0.53). The anteroposterior maxillary incisor position relative to the forehead between the control and study groups was significantly different (P < .0001). In addition, the forehead inclination between the control and study group was significantly different (P < .05). CONCLUSION The forehead is an important landmark for anteroposterior maxillary incisor positioning for adult white male patients seeking improved facial harmony.

Comparison of computer-generated, enhanced and conventional 2-dimensional radiographic imaging

INTRODUCTION Technological advances have attempted to improve the standard of traditional x-ray imaging. ImageIQ software (LumenIQ, Bellingham, Wash) enhances conventional radiography by producing a computer-generated, enhanced 2-dimensional (2D) image, adding depth and detail. The software converts the scales of gray to topographic height values, which are easier for the eye to see. The purpose of this study was to determine whether the enhanced 2D renderings are as sensitive as traditional 2D radiographs for detecting periodontal defects in cadaver mandibles. METHODS Periodontal defects were located and classified on 20 cadaver mandibles. These defects were radiographed, and computer-generated, enhanced 2D topographic renderings were made with ImageIQ software. A panel of evaluators was shown the 2D radiographs and the enhanced 2D renderings in random order. The evaluators classified the defects from these images. RESULTS Significantly better agreement by the evaluators with the intrasurgical classification was found with the enhanced 2D rendering to view periodontal defects vs the traditional 2D x-ray. Enhanced 2D renderings improved the accuracy of radiographic periodontal defect classification by 14.3% over traditional 2D radiographs. CONCLUSIONS Computer generated, enhanced 2D renderings of conventional radiographs might provide a reliable diagnostic alternative to conventional 2D radiographs when attempting to classify periodontal defects.