Semester

Spring

Date of Graduation

2024

Document Type

Thesis

Degree Type

MS

College

School of Dentistry

Department

Orthodontics

Committee Chair

Peter Ngan

Committee Co-Chair

Khaled Alsharif

Committee Member

Guoqiang Guan

Abstract

ABSTRACT

Comparative cephalometric study between Class II patients treated with Herbst appliance and patients treated with MARA

Mona Meky, D.D.S.

Background and Objectives: Functional appliances have been used for over 100 years in orthodontics to correct Class II malocclusions. The Herbst and the MARA appliances have different designs that may enhance mandibular growth. Recent clinical evidence has questioned whether they really have a lasting influence on facial growth and that the effects of these appliances were mostly dentoalveolar rather than skeletal. The objective of this retrospective comparative study was to compare the dental and skeletal changes between Class II division 1 malocclusions treated with the Herbst and the MARA appliances.

Experimental Design and Methods: This is a retrospective study comparing twenty-eight patients treated with the Herbst appliance and twenty-eight patients treated with the MARA appliances. Orthodontic records were obtained in Dr. Neal Kravitz’s private practice in Northern VA. The stage of dental development varied from late mixed dentition to early permanent dentition. The skeletal maturation of the patient samples was matched as close as possible using the CVM method. Patients with a CVM between stages 3 and 4 were included in the sample. Lateral cephalogram was taken before treatment , immediately following the removal of the appliance, and following completion of fixed appliance therapy for the Herbst sample (T1, T2, T3) and the MARA sample (t1, t2, t3). Dental and skeletal changes were recorded using the Dolphin digital software. Data were analyzed using a two sample t test for the craniofacial morphology, a matched pair t test Wilcoxon signed rank test for the skeletal and dental changes across three time periods. Significant differences between the two treatment groups in changes across the three treatment time periods were analyzed by a two sample t tests. Intra-rater reliability for treatment changes were analyzed using the Intra-class correlation coefficients (ICCs). A two-sided p-value of less than 0.05 was considered statistically significant.

Results: The average total treatment time in the functional appliance was 11.3 +1.1 for Herbst and 11.2 +1.2 months for MARA. Significant differences were found in the reduction of overjet, change in molar relationship and overbite with the Herbst and the MARA appliances. The change in overjet and molar relationships were attributed to restriction in the forward movement of the maxilla, more forward movement of the mandible, backward movement of the maxillary molars, and forward movement of the mandibular molars. Greater reduction in the overjet was seen with the Herbst compared to the MARA appliance. There was also more skeletal contribution to the reduction in overjet and change in molar relationship seen with the Herbst sample. After comprehensive therapy, both groups maintained a reduction in overjet and overbite as well as a Class I molar relationship. The change in overbite was similar between the Herbst (1.9mm) and the MARA (2.0mm) groups. There was greater eruption of the maxillary incisors seen with the MARA (0.58mm vs. 0.06mm). Greater proclination of the lower incisors was seen in the MARA group (4.72° vs. 4.46°).

Conclusion: Both the Herbst and MARA appliances were effective in the reduction of overjet and correcting the molar relationships into a Class I molar relationship with treatment for 9-12 months. A large part of the correction is due to the fact that the patients were in their peak growth spurt. The treatment changes were greater with the Herbst appliance due to the headgear effect on the maxilla. There was more proclination of the lower incisors seen with the MARA group.

Embargo Reason

Publication Pending

Available for download on Tuesday, April 01, 2025

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