A cephalometric study to compare the effects of cervical traction and Andresen therapy in the treatment of class II division 1 malocclusion. Part 2--Dentoalveolar changes

Occlusal and cephalometric Class II Division 1 malocclusion severity in patients treated with and without extraction of 2 maxillary premolars

INTRODUCTION

The purpose of this study was to compare the initial occlusal and cephalometric severity of Class II Division 1 malocclusion patients treated with and without extraction of 2 maxillary premolars.

METHODS

Dental study models and cephalograms of 62 patients were selected. Those in group 1 (n = 42) were treated without extractions, and those in group 2 (n = 20) were treated with 2 maxillary premolar extractions. Grainger's treatment priority index (TPI) was used to assess the final and the initial occlusal status of each subject. Variables such as overjet and overbite were also evaluated. Independent t tests were used to compare the occlusal variables at the posttreatment stage, the occlusal and cephalometric variables at the pretreatment stage, and the improvement in TPI values between the groups.

RESULTS

Patients treated with 2 maxillary premolar extractions had greater initial occlusal TPI values, overjets, cephalometric apical base anteroposterior discrepancies, maxillary incisor protrusions, and anteroposterior molar discrepancies than those treated without extractions.

CONCLUSIONS

For patients with more severe anteroposterior discrepancies, an extraction plan provides more effective treatment with less need for patient compliance.

Associations between changes in selected facial dimensions and the outcome of orthodontic treatment

The purpose of this study was to determine, in children with Class II, Division I malocclusion who were treated with functional appliances, the strength of the associations between the changes over 18 months in selected facial dimensions and the success of orthodontic treatment as determined by the weighted Peer Assessment Rating (PAR). Forty-two children, between 10 and 13 years of age (mean age 11.6 years), were randomly assigned to either an untreated group (control) or a group treated with either a Fränkel function regulator or Harvold activator (treatment). The outcome of treatment was assessed on study models and the craniofacial changes were measured on lateral cephalometric radiographs. Correlation coefficients were then calculated between the differences in the cephalometric variables over 18 months and the differences in the PAR scores. In the treatment group, the effects of normal growth were held constant by partial correlation. The partial used was the change in both stature and weight. Significant positive partial correlations were found between the increases in total anterior face height, posterior face height, S-Pg, and treatment success. Significant negative partial correlations were found between downward movement of the maxilla and mandibular body and lower anterior face height and treatment success. It is postulated that these associations occurred mainly in response to the bite opening by the appliances. Treatment success was also significantly associated with maxillary restriction, an increase in the SNB angle and a reduction in the ANB angle. Changes in B point due to proclination of the mandibular incisors were considered to be responsible for the two latter significant associations. Although mandibular length increased significantly in the treatment group, as compared with the control group, it was not significantly associated with treatment success.

Maxillary and cranial base changes during treatment with functional appliances

The purpose of this prospective study was to investigate the maxillary and the cranial base changes after treatment with the Harvold activator and the Fränkel function regulator appliances. Forty-two children, who are 10 to 13 years old, with Class II, Division 1 malocclusions were matched in triads according to age and sex and randomly assigned to either the control, Harvold activator, or Fränkel function regulator group. Lateral cephalometric radiographs were taken at the start of the study and 18 months later. Both appliances reduced the overjet by tipping the maxillary incisors palatally and, as a consequence, the length of the maxillary arch was reduced. The appliances had no effect on either the horizontal or vertical position of the maxillary molars. Small, but statistically significant, changes in the cranial base angle in the Fränkel function regulator group were attributed to relatively large changes at basion in several children, influencing the results because of the small size of the sample. The appliances had no effect on the position of the maxilla.

Three-dimensional diagnosis and management of Class II malocclusion in the mixed dentition

Class II malocclusion is a commonly observed problem, occurring in about one third of the United States population. The numerous treatment approaches that have been advocated to treat this malocclusion presumably produce differing treatment effects within the skeletal, dentoalveolar, and soft tissue components of the face. In the first section of this article, the three-dimensional components of Class II malocclusion are described, with transverse maxillary discrepancy, mandibular skeletal retrusion, and increased lower anterior facial height observed as common findings in a mixed dentition sample of Class II subjects. Second, the literature concerning two seemingly diverse treatment methods (extraoral traction and functional jaw orthopedics) is reviewed in detail. Last, cephalometric data are presented from a retrospective clinical study and is used to evaluate the treatment effects produced by cervical traction and the FR-2 appliance of Fränkel in comparison with an untreated sample of mixed dentition Class II patients. The results of this study indicated that although both skeletal and dentoalveolar components of Class II, Division 1 malocclusion were altered in the Class I direction by either a facebow or a Fränkel appliance, these two appliance systems accomplished the correction in dramatically differing ways. Cervical traction affected the skeletal and dentoalveolar components of the maxilla and mandible, whereas the FR-2 appliance had less of an effect on maxillary and dentoalveolar components and a greater effect on mandibular length. Thus, these two treatment modalities produce decidedly different treatment effects in patients with Class II malocclusions.

Long-term stability of Class II, Division 1, nonextraction cervical face-bow therapy: II. Cephalometric analysis

The long-term stability of Class II, Division 1 nonextraction therapy, using cervical face-bows with full fixed orthodontic appliances was evaluated for 42 randomly selected patients. Part 1, a study model analysis, was published in the March 1996 issue of the JOURNAL. Each patient was treated by the same practitioner, with the same techniques, and the treatment goals had been attained for all patients. Pretreatment records were taken at a mean age of 11.5 years; the posttreatment and postretention records were taken 3.0 and 11.6 years later, respectively. The results showed that the ANB angle decreased 2 degrees during treatment, most of which was due to the 1.6 degree decrease of the SNA angle. The mandibular plane angle was not changed significantly during treatment. Although upper incisor inclination was maintained during treatment, the lower incisor was proclined 2.3 degrees and the lower molar was tipped back 4 degrees. Of the 22 cephalometric measures evaluated, only four indicated relapse related with the treatment change. Three of the four measures pertain to lower incisor retroclination subsequent to excessive proclination. The ratio of treatment proclination of incisors to posttreatment retroclination is approximately 5:1. Similarly, for every 3 degrees of molar tip back, there was approximately 1 degree of relapse. It is concluded that nonextraction therapy for Class II malocclusion can be largely stable when the orthodontist ensures proper patient selection and compliance and attains treatment objectives.

Long-term stability of Class II, Division 1, nonextraction cervical face-bow therapy: I. Model analysis

The long-term stability of Class II, Division 1 nonextraction therapy remains poorly described. This study evaluates the face-bow therapy, in conjunction with full-fixed appliance therapy, of 42 patients (34 females and 8 males) who were treated by the same practitioner. Treatment goals had been attained for all patients. The pretreatment, posttreatment, and postretention records were taken at 11.5, 14.5, and 23.1 years, respectively. The results showed that mandibular and maxillary arch widths were increased significantly during treatment. Mandibular intercanine width decreased 0.3 mm during the postretention period; the remaining width measures increased or remained stable. Arch length, which did not change during treatment, decreased 1.0 mm after treatment. Overjet and overbite decreased 4.4 mm and 2.5 mm, respectively, during treatment. Both overjet (0.5 mm) and overbite (0.4 mm) showed small increases after retention. Mandibular incisor irregularity was decreased 2.7 mm during treatment and increased only 0.4 mm after treatment. Within the limits of this study, it is concluded that, when the described techniques are used, nonextraction therapy for patients with Class II malocclusion is largely stable.

Long-term stability of Angle Class II, division 1 malocclusions with successful occlusal results at end of active treatment

The purpose of this study was to examine long-term stability of Angle Class II, Division 1 malocclusions with successful occlusal results at the end of active appliance therapy, search for predictors of relapse, and look for characteristics associated with successful treatment. Records taken before and after treatment and a mean of 14.0 years postretention of adolescent patients treated for a significant Angle Class II, Division 1 malocclusion both with and without tooth extraction were evaluated. The sample was limited to successfully treated cases as judged by subjective evaluation of intercuspation and incisor occlusion of posttreatment study models and included 78 patients. Cephalometric characteristics or postretention occlusion was not considered in sample selection. The mode response was no change postretention for molar, premolar, and canine relationships and relapse of 0.5 mm for overjet and overbite. Maximum relapse was 3.5 mm for molar, premolar, and canine relationship, 3 mm for overjet, and 4.5 mm for overbite. Stepwise backward multiple regression analyses revealed no associations between either pretreatment characteristics or skeletal and dental treatment changes and relapse of overjet. However, relapse of overjet was associated with relapse of molar, premolar, and canine relationships, postretention increase in overbite, postretention proclination of maxillary incisors, and postretention retroclination of mandibular incisors. Active treatment changes included redirection or inhibition of maxillary growth and retraction of maxillary incisors. Mandibular incremental growth was favorable both during and after treatment. It was concluded that successful correction of Angle Class II, Division 1 malocclusions through differential growth adaptation and tooth movement appears to be very stable.

Stability of the lower labial segment following orthodontic treatment--a comparison of treatment with Andresen and Begg appliances

This retrospective cephalometric study of Class II division 1 malocclusions investigates the effects on the lower labial segment of two forms of orthodontic treatment. Non-extraction Andresen myofunctional therapy and first premolar extraction Begg treatment are compared to the lower incisor changes found in appropriate non-extraction and first premolar extraction control groups, which also presented with Class II division 1 malocclusions. Using four angular and two linear measurements, the lower labial segment was found to procline during Andresen therapy (1-2 degrees, 1-2 mm), and on withdrawal of the appliance it retroclined by about one-half of the in-treatment proclination (0.4-0.8 degrees, 0.1-0.5 mm). During extraction Begg mechanics, the lower incisors were found to retrocline (1.3-1.5 degrees, 0.4-0.9 mm), and they continued to retrocline following removal of the appliance (0.2-3.0 degrees, 0.8-1.1 mm). In general, the variables used to measure lower incisor position demonstrated only very small changes, and were near method error. The reliability of these changes are discussed. It is considered that the axial inclination of the lower incisor in relation to the mandibular plane is the most consistent and therefore still the most useful clinical measurement of lower incisor change available from cephalometric radiographs.