Skeletal and dental effects of a novel application of the MARA appliance in adolescent patients with Class II malocclusions.

Garrett Rand Criswell, DDS, MBA

Purpose: The objectives of this study were to test the hypotheses that there is no significant increase in mandibular growth, no significant inhibition of maxillary growth, no significant relationship between mandibular inclination and mandibular growth, and no significant molar changes in patients treated with the MARA appliance compared to subjects who had no treatment intervention.

Methods: This is a retrospective longitudinal study of early adolescents with Class II malocclusions treated concurrently with the Mandibular Anterior Repositioning Appliance (MARA) and fixed Edgewise appliances over an extended duration (mean 3.5 years). The study was based on successive lateral cephalometric headfilms of 17 individuals (10 females and 7 males) from a private orthodontic office and on 9 control subjects matched for age, malocclusion, skeletal makeup and adequate records.

Results: The findings in this study show that concurrent MARA and fixed Edgewise appliance treatment did not result in any statistically significant difference in mandibular length (Ar-Pg), mandibular prognathism (SN-Pog), or maxillary position (SNA) when compared to the control group either for T1-T2 (mean 13 months) or during the overall period from T1-T3. During the course of treatment, the mandibular inclination and lower anterior facial height increased significantly. Pretreatment mandibular inclination did not have any measurable influence on the change in mandibular length or mandibular prognathism. Compared to controls, the maxillary molars experienced more distal tip and restricted forward movement, while the mandibular molars moved forward and extruded more, though none were statistically significant.

Conclusions: Treatment of Class II malocclusions with the concurrent use of the MARA and Edgewise appliances for an extended duration of time did not result in any statistically significant skeletal effects on the maxilla or mandible except for increasing the mandibular inclination and lower anterior facial height. The Class II malocclusion was effectively treated to a Class I occlusion in all subjects with the use of the MARA and Edgewise appliances largely through dental changes and some skeletal changes that were individually not statistically significant. There was significant individual variation in response to treatment.

Introduction

Obstructive sleep apnea (OSA) is characterized by breathing disturbances during sleep, and daytime sleepiness.1 Prevalence of OSA has been cited as 3-33% for men and 2-9% for women.2-4 Risk factors for OSA include obesity, male gender, age, neck circumference, high blood pressure, and specific craniofacial anomalies.1,2,5,6 Craniofacial findings in OSA patients include an inferiorly-positioned hyoid relative to the mandibular plane, a relatively shorter maxilla and mandible, larger overjet, an increased mandibular plane angle, and an increased ANB angle.7-10 Our hypothesis is that in an adult orthodontic patient population, specific skeletal cephalometric measurements can distinguish between OSA high-risk and low-risk patients, and that there is a preventive effect of orthognathic surgery in young adulthood for developing OSA later in life.

Materials and Methods

We conducted a cross-sectional study evaluating OSA risk in adult orthodontic and orthognathic surgery patients from the UCSF Orthodontic and Oral and Maxillofacial Surgery clinics. We used a questionnaire composed of the Berlin Questionnaire (BQ), and the Epworth Sleepiness Scale (ESS) to assess the risk of OSA. Each orthodontic subject's lateral cephalogram was digitized. Logistic regression was used to evaluate the association between the subjects' specific cephalometric measurements, and the results of the BQ and ESS.

Results

27 orthodontic subjects and 28 surgical subjects were included. In the orthodontic group, none of the female subjects and 4 of the male subjects scored `high-risk' on the BQ. Male gender (p < 0.05) was found to be significantly associated with being classified as `high-risk' by the BQ in the orthodontic patient group. No difference was found in the BQ and ESS results of the orthodontic and surgical groups. The mandibular plane to hyoid distance (MPH) was found to be moderately associated with being classified as `high-risk' by the BQ (p < 0.1).

Conclusions

1. Our questionnaire serves as an excellent screening tool for orthodontic patients.

2. Prevalence of probable OSA was found to be 40% for males and in 0% of the females in this study's orthodontic patient population.

3. There is a positive association between likelihood of OSA and the following factors: male gender, and an inferiorly-positioned hyoid.