The aim of this prospective, randomized study was to analyze dental and skeletal side effects after 4 years of treating obstructive sleep apnea (OSA) patients with a mandibular advancement device (MAD) compared with uvulopalatopharyngoplasty (UPPP). With the appliance in position, the mandible was advanced 50% of maximum protrusion capacity (ie, 4-6 mm); the vertical opening between the incisal edges was, on average, 3 mm. Thirty patients in the MAD group and 37 in the UPPP group completed the 4-year follow-up. There were no differences between the MAD and the UPPP groups in any of the dental or skeletal variables measured after the 4-year treatment period. In the MAD group, small but statistically significant changes were found: there was a posterior rotation of the mandible (mandibular line [ML]/nasion-sella line [NSL]) (mean 0.5 degrees [95% confidence interval (CI) 0.1-0.8 degrees ]). Correlated to the posterior rotation of the mandible, the distances incision superius ML, incision superius-NSL, and incision inferius-NSL increased by means (95% CI) of 0.7 (0.5-1.2), 0.8 (0.4-1.1), and 1.3 (0.8-1.8) mm, respectively. Overjet and overbite did not change significantly, nor was there a significant change in the mandibular length. The observed changes were considered clinically insignificant because overbite and overjet stayed within normal limits. Only the vertical position of the maxillary incisors in relation to ML changed to the extent that the 95% CI of the mean for the change was outside that of the mean of the change in the UPPP group and measurement error. Treatment of OSA with a dental appliance is probably a lifelong process, and long-term follow-up studies should therefore be undertaken to control both the treatment effect on OSA and the side effects on the masticatory system.

The enthusiasm for uvulopalatopharyngoplasty (UPPP) in the treatment of obstructive sleep apnoea (OSA) has declined in recent years, partly because of a lower success rate over time and partly because of adverse effects. Reports on the beneficial effects of dental appliances exist, but only one prospective randomized study has been published comparing dental appliances with nasal continuous positive airway pressure (CPAP) treatment. No study has been published comparing dental appliance treatment with UPPP. Ninety-five male patients with confirmed OSA, subjective daytime sleepiness and an apnoea index (AI) > 5 were randomized for subsequent treatment with either a dental appliance or UPPP. There were 49 patients in the dental appliance group and 46 in the UPPP group. Thirty-seven patients in the dental appliance group and 43 in the UPPP group completed the 12-month follow-up. The success rate (rate of patients with at least a 50% reduction in AI) for the dental appliance group was 95%, which was significantly higher (p < 0.01) than the 70% success rate for the UPPP group. According to the criteria for OSA (apnoea index > or = 5 or apnoea/hypopnoea index > or = 10), 78% of the dental appliance group and 51% of the UPPP group were normalized after 12 months. The difference between the groups was significant (p < 0.05). These findings suggest that the dental appliance technique is useful in the treatment of mild to moderate OSA.

In a prospective study, 95 patients with mild to moderate obstructive sleep apnoea (OSA) were randomised to receive either surgical treatment, uvulopalatopharyngoplasty, (4-6 patients) or treatment with a nocturnal dental appliance for mandibular advancement (49 patients). Of the 49 dental appliance patients, 37 completed the 12-month follow-up. The aim of this study was to evaluate the effects and adverse events of dental appliance treatment from a one-year perspective. Somnography was employed to measure treatment effects before and 12 months post-treatment. At the 12-month control, somnography was performed twice: the first time with the dental appliance and the second time without it. Adverse events were recorded 2 weeks and 3, 6, and 12 months after treatment was initiated. The patients used the dental appliance on average 6 nights/week. After 12 months of treatment, the apnoea, apnoea/hypopnoea, oxygen desaturation, and snoring indices decreased significantly. Ninety-five per cent of the patients reduced their apnoea index by > or = 50% and 78% of the patients were normalised following treatment. At the somnographic registration without the dental appliance, the values were found comparable to what they were before treatment. Mandibular mobility and occlusion were constant throughout the study. The adverse events resulting from using the dental appliance were relatively minor and infrequent, and no serious complications were observed except for two patients who reported pain from the temporomandibular joint. In conclusion, the dental appliance has been shown to be a valuable treatment method for mild to moderate OSA with few adverse events in the stomatognathic system or other complications.

In a prospective randomized study on treatment of obstructive sleep apnea syndrome, anterior-inferior mandibular osteotomy with the purpose of stretching the suprahyoidal muscle was performed as one of the treatment methods. Ten men aged 20 to 65 years, without cardiovascular or neurologic disease, with normal maxillomandibular relation, and having an apnea index between 5 and 25 were included in the study. After a specially designed osteotomy of the chin, the anterior suprahyoidal muscles were detached, stretched approximately 10 to 12 mm, and sutured. The chin was then placed in its original position and post-operative evaluation was performed. Although there were initial reports of decreased daytime sleepiness and less snoring after surgery, the results after 12 months were discouraging. Somnographic registration (apnea index, apnea/hypopnea index, and oxygen desaturation index) as well as cephalometric analysis failed to show positive results. Hence, suspension of the suprahyoidal muscles as a method of treatment for obstructive sleep apnea syndrome cannot be recommended.

In 30 patients posterior repositioning of the entire maxilla has been performed. No postoperative intermaxillary fixation (IMF) has been applied. The surgical procedure is described and data given on the distance of repositioning. Results of cephalometric analysis indicate good long-term stability after surgery. We concluded that omitting IMF not only enhances patient comfort, but has no deleterious effect on postoperative stability of the maxilla.

A modified sagittal split technique has been evaluated in 42 dentate patients, in whom no postoperative intermaxillary fixation was used. Twenty-three patients had mandible set-back performed and 19 patients mandibular advancement. The method makes possible a safe split osteotomy under controlled conditions. The design of the osteotomy and screw osteosynthesis counteracts relapse. Omitting intermaxillary fixation facilitates postoperative handling of the patient and promotes rehabilitation.

Simultaneous correction of maxillary and mandibular anomalies was performed in 23 patients. The maxillary segment was stabilized by means of steel wires as horizontal mattress sutures, which, in all cases, gave good stability. A modified sagittal split has been applied in all cases. The method makes a safe split osteotomy possible under controlled conditions. The design of the osteotomy and the screw osteosynthesis counteract relapse. Postoperatively, no rigid intermaxillary fixation (IMF) was used. Masticatory function was started from the 1st postoperative day and in most cases was normalized 2-3 weeks after surgery according to the patients own judgement. Cephalometric analysis was performed on 15 patients by a superimposition technique. There was an overall good postoperative stability of the maxilla and mandible in the horizontal and vertical planes. We conclude that omitting IMF has no negative effect on the postoperative stability of the fragments.

Histochemical staining methods were applied to selected superficial forearm muscles of Macaca mulatta monkeys. The muscles were analyzed with regard to relative percentage distribution of different fiber types. In extensor carpi radialis brevis, extensor carpi radialis longus, and palmaris longus there was an even dispersion of each fiber type from the superficial to the deep part of the muscle. Extensor digiti communis showed a slightly higher percentage of type I fibers and correspondingly lower percentage of type II fibers in its central as compared to its superficial area. Three muscles, bracioradialis, extensor carpi ulnaris, and flexor carpi radialis, displayed marked differences between their superficial and deep areas. All of them contained a higher proportion of type I fibers (and correspondingly lower percentage of type II fibers) in their deep parts than in their superficial areas. Flexor carpi ulnaris (FCU) differed from the other muscles studied in that it showed distinctly different fiber proportions on either side of a central tendon. While the ulnar head of FCU was dominated by type II fibers (71% compared to 27% type I fibers), the humeral head contained a larger proportion of type I fibers (58% vs. 40% type II fibers). This difference in fiber type distribution suggests different functional demands for the two heads of FCU, with the possibility of more sustained activity in the humeral head.

Human fetal muscles have been studied using immunocytochemical methods with antibodies directed against different myosin isoforms. We show that fiber type differences can be detected as early as 15–16 weeks of gestation. At this time it would appear that both the heavy and light chains characteristic of slow myosin are found in some myotubes.

On the basis of enzymic properties, different fibre types can be distinguished in human skeletal muscle (type I fibres and type II fibres with subtypes) and there is a correlation between fibre types and the occurrence of slow and fast myosin. In human masticatory muscles, fibres with ATPase activity at pH 9.4, intermediate between that of type I (low activity) and type II (high activity), are frequent. On cryostat-sectioned material, highly specific antibodies against fast myosin, slow myosin and slow light chains were applied. The myosin composition of human masticatory muscles was very heterogeneous, in contrast to that in limb muscles, with various proportions of slow and fast myosins, heavy as well as light chains. Type I fibres contained slow myosin only and type II mainly fast myosin, ATPase IM and type IIC fibres contained a mixture of slow and fast myosins in variable amounts. The findings conform with physiological evidence of a continuum of contraction times for motor units in the human masticatory muscles and suggests that these muscles are highly adapted to the special and complicated functions of the stomatognathic system.

The histochemical muscle-fibre composition of the anterior and posterior belly of the human digastric muscle was analysed in young male adults. Both bellies, of differing embryological origin and supplied by different cranial nerves, showed a fibre composition similar to that of normal limb and trunk muscles. Type I, type IIA and type IIB fibres each occupied about one-third of the total fibre population and were evenly distributed in a mosaic pattern. About 1 per cent of fibres were type IIC and ATPase (pH 9.4) intermediate fibres. Thus, there were major differences between the anterior belly of digastric and the likewise trigeminal nerve innervated masticatory muscles with respect to both histochemical profile and size and distribution of various types of fibre. The observations suggest that the fibre pattern of the digastric is not primarily related to its specific nervous supply but its special functional demands. The predominance of type II fibres indicates a capacity for fast acceleration and speed in mandibular movements. The disparity in fibre-type profile between the digastric and the jaw elevator muscles might be related to changing demands during evolution. Civilized diets need no heavy mastication and, while the requirements upon the jaw elevators have thus changed, the functional demands on the jaw openers would have remained unchanged.

A histochemical characterization of the masseter muscle was performed on biopsy samples of dentate subjects with normal occlusion. There was a continuum of ranges of oxidative and glycolytic capacities of the masseter muscle fibres.

The histochemical fibre-type profile was analyzed in 10 human lateral pterygoid muscles from young adults with complete dentitions and normal intermaxillary relations. The distributions of various types of fibre in the lateral pterygoid differed from those of normal human limb and trunk muscles as well as from those of human masseter and temporal muscles. There was a marked predominance of type I fibres, a high frequency of adenosine triphosphatase (ATPase) intermediate fibres and type IIC fibres and lack of type IIA ones. The muscle fibres, especially the type II fibres, were smaller than those in limb and trunk muscles. There was marked intra-muscular variability in both the proportion and diameter of the types. Type I fibres were larger in diameter than the others and occupied, on average, 81 per cent of the overall fibre crass-sectional area. Type II and the ATPase intermediate fibres were larger in males than in females. There was no difference in type I fibre diameter or fibre-type proportion between females and males. No difference in fibre diameter was observed between the two heads of the muscle, but the proportions of fibre types differed significantly in four muscles. The fibre-type composition in the adult lateral pterygoid muscle indicates a capacity for endurance during continuous work at relatively low forces and accords with the stabilizing effect on the mandibular joint attributed to this muscle.

The reliability of muscle fibre typing of post mortem specimens was investigated with special reference to the influence of time and temperature. In specimens stored at +4° C, muscle fibre typing could be reliably performed up to at least ten and fifteen days post mortem for the masseter and biceps brachii muscles respectively. The corresponding figures for storage at room temperature were three and six days. The difference in the preservation of enzyme activity between masticatory and limb muscles might be related to the demonstrated difference in the fibre type composition and thus the enzyme content and energy sources.

Masseter, temporal and biceps brachii muscles were histochemically evaluated for fibre type differentiation in 19 aborted fetuses (gestational ages 15–23 weeks), in 2 premature infants of 34 and 36 weeks gestation and in 2 fullterm stillborn infants. There was no convincing evidence of fibre type differentiation in the masticatory muscles before 22 weeks' gestation while a fairly distinct differentiation was seen in biceps brachii specimens at 16 weeks' gestation with ATPase at pH 4.35. Around 22 weeks two types of fibre were found in all specimens with ATPase at pH 4.35. With regular ATPase (pH 9.4) there was a relatively weak difference in staining between different types of fibre in the masticatory muscles. In biceps brachii Type I and Type II were demonstrated. Neonatally 3 levels of staining were seen in biceps brachii with regular ATPase (pH 9.4); while ATPase at pH 4.35 and 4.6 demonstrated the subtypes IIB and IIC. In the masticatory muscles only 2 levels were recognized with regular ATPase and all type II fibres had the characteristics of Type IIC as seen with ATPase at pH 4.35.

Histochemical staining methods were applied to biopsy specimens from the masseter muscles of 17 healthy subjects with mandibular prognathism and 4 subjects with benign parotid lesions. Fibre sizes and percentage fibre distributions were assessed in transverse sections stained for myofibrillar ATPase at pH 9.4. Size or percentage distribution of different fibre types was not significantly correlated to the state of occlusion. In subjects with unilateral chewing only, the frequency of Type I fibres (lightly stained) was higher (P < 0.01) and the frequency of intermediate fibres (moderately stained) lower on the chewing side than on the non-chewing side (P < 0.05). Type I fibres were invariably larger than Type II (strongly stained) fibres—mean value 33.2 μm versus 17.9 μm. There was no significant relationship between the sizes of Type I and Type II, but there was between Type I and intermediate fibres (P < 0.05). Intermediate fibres were generally intermediate in size to Type I and Type II, mean value 23.8 μm. The range of percentage distribution of the 3 types of fibres was wide. Average values were Type I 29%, type II 57% and intermediate fibres 14%. There was an indication that fibres from different depths of the muscle differ in size and in percentage distribution. The size of Type I and its percentage distribution were significantly negatively correlated (P < 0.01). The percentages of Type II and intermediate fibres were negatively correlated (P < 0.001) but not those of Type I and intermediate fibres. It is suggested that ATPase-intermediate fibres may result from transformation of Type II fibres.