The Use of Oral Appliances for the Treatment of Obstructive Sleep Apnea Is Now Well Estab-

effects following the use of mandibular advancement in the treatment of obstructive sleep apnea. A study has subsequently been designed to investigate these issues. Design: 100 consecutively treated medically referred patients were reviewed cephalometrically in 6-month intervals (6—30 months) following mandibular advancement therapy. Setting: Orthodontic Private Practice. Patients: 87 males, 13 females (mean age 49 years, SD 8.5, range 3374 years). Interventions: N/A Measurements and Results: Reference points and planes in the cranial base, maxilla, and mandible were digitized with a reflex metrograph and their means converted to linear and angular measurements. Significant changes following mandibular advancement were observed in lower face height, vertical condylar position, incisor angulation, overbite, and overjet. Skeletal changes were attributed to a vertical repositioning of the mandibular condyle relative to the cranial base and were present at the first review period (6 months). Dental changes occurred later with treatment with the most significant changes occurring at the final review period (30 months) which resulted in a 4.9° proclination of the mandibular incisors and a reduction in overbite of 1.82mm. Conclusion: The data suggests that long-term use of mandibular advancement can cause dental and skeletal changes which may be progressive over time. As many consider mandibular advancement a treatment for life, it is strongly recommended that all patients be fully informed of the potential for such changes prior to treatment and undergo mandatory dental reviews with long-term mandibular advancement.