Katherine W.L. Vig

Root resorption associated with orthodontic tooth movement: a systematic review.

INTRODUCTION This systematic review evaluated root resorption as an outcome for patients who had orthodontic tooth movement. The results could provide the best available evidence for clinical decisions to minimize the risks and severity of root resorption. METHODS Electronic databases were searched, nonelectronic journals were hand searched, and experts in the field were consulted with no language restrictions. Study selection criteria included randomized clinical trials involving human subjects for orthodontic tooth movement, with fixed appliances, and root resorption recorded during or after treatment. Two authors independently reviewed and extracted data from the selected studies on a standardized form. RESULTS The searches retrieved 921 unique citations. Titles and abstracts identified 144 full articles from which 13 remained after the inclusion criteria were applied. Differences in the methodologic approaches and reporting results made quantitative statistical comparisons impossible. Evidence suggests that comprehensive orthodontic treatment causes increased incidence and severity of root resorption, and heavy forces might be particularly harmful. Orthodontically induced inflammatory root resorption is unaffected by archwire sequencing, bracket prescription, and self-ligation. Previous trauma and tooth morphology are unlikely causative factors. There is some evidence that a 2 to 3 month pause in treatment decreases total root resorption. CONCLUSIONS The results were inconclusive in the clinical management of root resorption, but there is evidence to support the use of light forces, especially with incisor intrusion.

The Accuracy and Reliability of Measurements Made on Computer-Based Digital Models

For reasons of convenience and economy, orthodontists who routinely use and maintain pre- and posttreatment plaster casts are beginning to use computer-based digital models. The purpose of this study was to determine the accuracy (validity), reproducibility (reliability), efficacy, and effectiveness of measurements made on computer-based models. A plastic model occlusion ie, dentoform, served as a gold standard to evaluate the systematic errors associated with producing either plaster or computer-based models. Accuracy, reproducibility, efficacy, and effectiveness were tested by comparing the measurements of the computer-based models with the measurements of the plaster models--(1) accuracy: one examiner measuring 10 models made from a dentoform, twice; (2) reproducibility and efficacy: two examiners measuring 50 models made from patients, twice; and (3) effectiveness: 10 examiners measuring 10 models made from patients, twice. Reproducibility (reliability) was tested by using the intraclass correlation coefficient. Repeated measures of analysis of variance for multiple repeated measurements and Students t-test were used to test for validity. Only measurements of maxillary and mandibular space available made on computer-based models differed from the measurements made on the dentoform gold standard. There was significantly greater variance for measurements made from computer-based models. Reproducibility was high for measurements made on both computer-based and plaster models. In conclusion, measurements made from computer-based models appear to be generally as accurate and reliable as measurements made from plaster models. Efficacy and effectiveness were similar to those of plaster models. Therefore, computer-based models appear to be a clinically acceptable alternative to conventional plaster models.

Early fracture of the mandibular condyles: frequently an unsuspected cause of growth disturbances.

Experience with patients referred to the Dentofacial Clinic at the University of North Carolina indicates that previous fracture of the mandibular condylar process may be involved in 5 to 10 percent of all severe mandibular deficiency or asymmetry problems. Since these fractures often go undiagnosed and since three fourths of the children with fractures have no growth deficits, the incidence of condylar fractures probably is much higher than commonly thought. Management of fracture patients immediately following the accident, during the postinjury stages of mandibular growth, and at completion or near-completion of growth is discussed.

The validation of the Peer Assessment Rating index for malocclusion severity and treatment difficulty

The Peer Assessment Rating (PAR) index is a British occlusal index that measures the severity of dental malocclusion and has been used in several investigations that have evaluated the effectiveness of orthodontic treatment provision in Europe. As part of its development, the PAR index was validated for malocclusion severity, by using the opinions of a panel of 74 dentists and orthodontists. The present investigation was carried out to validate the PAR index, by using the opinion of an American panel of orthodontists. Eleven orthodontists examined a sample of 200 sets of study casts and rated them for malocclusion severity and perceived treatment difficulty. Multiple regression techniques were used to evaluate the predictive power of the components of malocclusion on the panels scores. Weightings were calculated from the partial regression coefficients and, when these weightings were applied to the PAR index, the association between the panels opinion and the PAR index scores was increased.

Delayed bone grafting in the cleft maxilla and palate: A retrospective multidisciplinary analysis

The results of delayed bone-grafting procedures in a group of twenty-four cleft patients are reported. All patients benefitted from closure of their fistulas. The need for a prosthesis was eliminated in twelve patients, and eight of the remaining twelve patients required only a three-unit bridge. Residual movement of the premaxilla in two of the nine bilateral cases included in this study was detectable. The esthetic benefits were difficult to assess since sixteen of the patients simultaneously underwent lip and nasal revisions. In seventeen patients, the graft was placed prior to canine eruption, and in sixteen of these patients, the canine erupted passively into the arch. Not every patient with a cleft is a candidate for delayed bone grafting, but the procedure has been found to be beneficial in selected persons.

Nasal obstruction and facial growth: The strength of evidence for clinical assumptions☆☆☆★

The orthodontic relevance of nasorespiratory obstruction and its effect on facial growth continues to be debated after almost a century of controversy. The continuing interest in nasal obstruction is fueled by strong convictions, weak evidence, and the prevailing uncertainty of cause and effect relationships that exist. The essence of any debate is to provide opposing evidence from which a majority vote is obtained. Political issues may be appropriately resolved by such means as a majority vote. Scientific issues, however, can only be resolved by data and appropriately structured hypotheses put to the test. One of the problems in debating nasorespiratory obstruction and facial growth is the inability to provide unequivocal answers to such issues as: How much nasal obstruction is clinically significant? At what age is the onset critical and for how long does it have to exist before an effect on facial growth can be expected? To provide unequivocal answers, clinical studies need to be designed to identify and quantify the degree of nasorespiratory obstruction and compare individuals for any clinically relevant differences. The purpose of this article is to review the available evidence. If both data and untested popular beliefs are subjected to the same rigorous criteria, indications for the orthodontic management of patients with nasorespiratory obstruction may gain a more rational approach to treatment recommendations.

Variables Affecting Measurements of Vertical Occlusal Force

Previous studies of occlusal force have provided conflicting results. The purpose of these studies was to determine whether the extent of vertical opening, contralateral occlusal support, or head posture influenced vertical occlusal forces during swallowing, simulated chewing, and maximum biting effort. Three samples of subjects with normal vertical facial proportions - one each of children, adolescents, and young adults - were evaluated to determine the effects of changes in small (2.5 vs. 6.0 mm) vertical separation of the first molars. A sample of young adults was used to evaluate changes in large (10-40 mm) vertical openings, and a sample of adolescents was used to investigate the effect of contralateral support and head posture. All between-group comparisons were evaluated using non-parametric statistics. For the small vertical openings, there was significantly more vertical occlusal force at 6.0 than 2.5 mm in children during swallowing and chewing but not during maximum biting effort. In adults, there was significantly more force during swallowing at 6.0 than at 2.5 mm separation, but no differences in chewing or maximum biting. Increasingly large vertical openings resulted in a progressive increase in maximum bite force to a maximum at about 20 mm, followed by a decrease and then a second increase to near-maximum force at about 40 mm for young adults. There were no significant differences in vertical force with or without contralateral support or between flexed, normal, and extended head postures at either of the small openings.

The effectiveness of Class II, Division 1 treatment

The aim of this retrospective study was to evaluate the effectiveness of orthodontic treatment in terms of two outcome variables, namely, the percentage change in a valid and reliable occlusal index, the Peer Assessment Rating (PAR) score, and the duration of treatment. Data were collected from the records of 250 patients with Class II, Division 1 malocclusions who were treated in the Orthodontic Department of the University of Pittsburgh between 1977 and 1989. The relationships between the outcome and the treatment variables were analyzed with multiple regression techniques. Those variables significantly associated with the duration of treatment (p < 0.01) were (1) the pretreatment PAR score, (2) the number of treatment stages, (3) the percentage of appointments attended, (4) the number of appliance repairs, and (5) whether the patient was treated with or without extractions. The only variable that influenced the percentage change in PAR was the pretreatment PAR score (p < 0.01).

Comparison of incisor inclination in patients with Class III malocclusion treated with orthognathic surgery or orthodontic camouflage.

INTRODUCTION Reports comparing Class III patients treated by camouflage and those treated by orthognathic surgery are not numerous. The purpose of this study was to compare the dental and skeletal values of Class III patients treated with these methods against normative data and over the course of treatment. METHODS Thirty-three surgical and 39 camouflage Class III patients were selected from a graduate orthodontic clinic and regional private practices, and lateral cephalograms were digitized. Skeletal and dental values were obtained, and mean and efficacy evaluations referenced to ethnic norms were calculated. RESULTS At pretreatment, the surgery patients had more severe skeletal discrepancies and more compensated incisors. During presurgical orthodontic treatment, most of the surgery groups mandibular incisors were significantly decompensated, although half of the maxillary incisors remained compensated. The surgical move improved 90% of these patients but to only 60% to 65% of the norm. The camouflage group was compensated at pretreatment, and they became more compensated in the end. After treatment, there were no differences between the incisor positions of the 2 groups. CONCLUSIONS There was no statistical difference in incisor inclination and position between the Class III surgical and camouflage groups after treatment; there was a significant difference in the pretreatment and posttreatment incisor inclination and position compared with normative values for both the surgical and the camouflage groups; the maxillary and mandibular incisors were not adequately decompensated in the surgical group, but significant improvement in mandibular incisor position and axial inclination was achieved presurgically. The outcome of the surgical correction was limited by the inadequate presurgical orthodontic incisor decompensation, and orthodontic compensation of incisors occurred postsurgically to achieve an optimal occlusal result.

Validity of the Index of Complexity, Outcome, and Need (ICON) in determining orthodontic treatment need.

Occlusal indices are used to determine eligibility for orthodontic treatment in several publicly funded programs. The Index of Complexity, Outcome, and Need (ICON), based on the perception of 97 orthodontists from 9 countries, has been proposed as a multipurpose occlusal index. The aim of this study was to investigate the validity of the ICON as an index of orthodontic treatment need compared with the perception of need as determined by a panel of US orthodontists. One hundred seventy study casts, representing a full spectrum of malocclusion types and severity, were scored for orthodontic treatment need by an examiner calibrated in the ICON. The results were compared with the decisions of an expert panel of 15 orthodontic specialists from the central Ohio area. The simple kappa statistic (0.81) indicated very high agreement of the index with the decisions of the expert panel. The sensitivity (94%), specificity (85%), positive predictive value (92%), negative predictive value (90%), and overall accuracy of the ICON (91%) also confirmed good agreement with the orthodontic specialists. The panel found that 64% of the casts required orthodontic treatment; the ICON scores indicated that 65% of the cases needed treatment. There was agreement between the expert panel and the index in 155 of the 170 cases. These results support the use of the ICON as a validated index of orthodontic treatment need.