|The overall purpose behind treatment in sleep-breathing disorders is to ease breathing and thereby reduce the risk of morbidity. The mandibular protruding device (MPD) is one method of treating both obstructive sleep apnea (OSA) and snoring. The aims of the studies were to study MPD users after 2 years and evaluate the following aspects of the MPD: subjective and objective effects on sleep, influences on airway passages and hard tissues, and the incidence and types of adverse events of the masticatory system including temporomandibular disorders. Further aims were to evaluate the impact of body posture and the effects of the MPD on pharyngeal width and to validate two methods for measuring mandibular protrusion and MPD advancement. MATERIALS AND METHODS: Seventy-seven subjects with OSA or snorers without OSA, were admitted to the study after a medical examination, which included a somnographic registration. The patients completed questionnaires regarding sleep quality and symptoms from the masticatory system, and underwent a clinical jaw function examination, were given an MPD, and were subjected to lateral cephalometric examination. Two follow-ups, 6 months and 2 years after MPD treatment were conducted. The study population comprised 65 patients at the 2-year follow-up. RESULTS: At the 2-year follow-up, a significant reduction of the subjective complaints was noted by 90% of the MPD users. In the objective evaluation, the oxygen desaturation index (ODI) of the OSA group (n=39) decreased significantly from a mean of 14.7 to 3.1 and the mean arterial oxygen saturation (SaO2) increased significantly from 78% to 89%. The snorers maintained their initial values. In the total group, MPD treatment significantly increased most pharyngeal measures and lifted the hyoid bone. The pharyngeal area decreased significantly - by more than 50% - when the patient was supine, and the velum area increased significantly. At the 2-year follow-up, on upright cephalogram without MPD, the pharyngeal area had significantly increased and the velum area had significantly decreased. The mandible was posteriorly rotated (P<0.01) as well as the lower incisors were proclined (P<0.05). Mandibular advancement and vertical opening with an MPD, as measured with a ruler, compared well with measurements taken from a cephalogram. At the 2-year follow-up significant changes in the mean mandibular range of protrusion (+0.6 mm), overjet (-0.5 mm), and overbite (-0.8 mm) were registered. Nine of the 65 patients had developed a lateral open bite, and 2 were aware of the change. The reported frequency of headache was significantly reduced. At the 2-year follow-up there was a significant reduction in pain during mandibular movements. CONCLUSIONS:MPD treatment significantly reduced subjective complaints of sleep disturbances and significantly reduced ODI values among OSA patients. A high MPD compliance rate after 2 years (84%) indicated a well-tolerated treatment and a low rate of side effects were noted. The key factor in OSA and snoring is the obstruction of pharynx. The MPD treatment significantly increased the pharyngeal passages and significantly reduced the size of velum and thereby facilitated the breathing.