Craniomandibular Complex Research Articles

Comparative osteology of the skull of cowbirds (Icteridae: Molothrus).

Detailed osteological descriptions of the craniomandibular complex of passerine birds are lacking for most species, limiting our understanding of their diversity and evolution. Cowbirds (genus Molothrus) are a small but widespread group of New World nine-primaried songbirds, well-known for their unique brooding parasitic behavior. However, detailed osteological data for cowbirds and other Icteridae are currently scarce and several features of their skulls remain undescribed or poorly known. To address this issue, a detailed comparative osteology of cowbird skulls is presented here for the first time based on data from x-ray microcomputed tomography, dry skeletal data, and multivariate analyses of linear morphometric data. Cowbird skulls offer some functional insights, with many finch-like features probably related to a seed-rich diet that distinguishes them from most other icterids. In addition, features previously overlooked in earlier studies might provide valuable phylogenetic information at different levels of passerine phylogeny (Passerida, Emberizoidea, Icteridae, and Agelaiinae), including some of the otic region and nasal septum. Comparisons among cowbirds show that there is substantial cranial variation within the genus, with M. oryzivorus being the most divergent cowbird species. Within the genus, distantly related species share similar overall skull morphology and proportions, but detailed osteological data allow species identification even in cases of strong convergence. Further efforts are warranted to furnish baseline data for future studies of this iconic group of Neotropical birds and to fully integrate it into phylogenetic comparative frameworks.

Evaluating stress and displacement in the craniomandibular complex using Twin Block appliances at varied angles: A finite element study

ObjectivesThe objective of this investigation was to assess the stress and displacement pattern of the craniomandibular complex by employing finite element methodology to simulate diverse angulations of inclined planes that are incorporated in the Twin Block appliance. MethodsA 3D finite element representation was established by use of Cone Beam Computed Tomography (CBCT) scans. This comprehensive structure included craniofacial skeletal components, the articular disc, a posterior disc elastic layer, dental elements, periodontal ligaments, and a Twin Block appliance. This investigation is the first to incorporated inclined planes featuring three distinct angulations (45, 60, and 70°) as the study models. Mechanical impacts were evaluated within the glenoid fossa, tooth, condylar, and articular disc regions. ResultsIn all simulations, the stress generated by the Twin Block appliance was distributed across teeth and periodontal ligament, facilitating the anterior movement of mandibular teeth and the posterior displacement of maxillary teeth. Within the temporomandibular joint region, compressive forces on the superior and posterior facets of the condyle diminished, coinciding with the stress configuration that fosters condylar and mandibular growth. Stress dispersion homogenized in the condylar anterior facet and articular disc, with considerable tensile stress in the glenoid fossa's posterior aspect conforming to stress distribution that promote fossa reconfiguration. The 70° inclined plane exerts the highest force on the tissues. The condyle's maximum and minimum principal stresses are 0.36 MPa and −0.15 MPa, respectively, while those of the glenoid fossa are 0.54 MPa and −0.23 MPa. ConclusionThree angled appliances serve the purpose of advancing the mandible. A 45° inclined plane relative to the occlusal plane exerts balanced anteroposterior and vertical forces on the mandibular arch. Steeper angles yield greater horizontal forces, which may enhance forward growth and efficient repositioning.

Optimization of the clinical diagnostic examination algorithm of patients with a cross bite complicated by cranio-mandibular dysfunction and postural disorder.

Aim: Optimization of the clinical and diagnostic examination algorithm of patients with cross bite, aggravated by cranio-mandibular dysfunction and postural disorders. Materials and Methods: 22 patients aged 13-16 years with cross bite with displacement of the lower jaw were examined. The first group consisted of 15 people with a right-sided displacement of the lower jaw, the second - 7 patients with a left-sided one. The condition of the musculoskeletal system was assessed by the position of the head, shoulders, shoulder blades, back (curvature of the spine), legs, chest shape, and abdomen. To determine the state of stability of the body in space, posturological and kinesiological tests were performed. The location of TMJ elements was evaluated on orthopantomograms. Statistical processing of the material was carried out with the help of the "Excel" license package. Results: 63.64% of patients with a cross bite have disorders of the musculoskeletal system: scoliotic posture - 40.91% and scoliosis - 22.73%. TMJ dysfunction was detected in all examined patients. It was established that the anatomical and topographic features of the joint elements depend on the side of the lower jaw displacement. Conclusions: The functional imbalance of all structural elements of the musculoskeletal system and the cranio-mandibular complex determined during the research proved the need to optimize the clinical-diagnostic algorithm: consultation of a traumatologist-orthopedic doctor, X-ray examination of TMJ, conducting posturological tests.

Effect of intervertebral disc degeneration on the stomatognathic system function in adults

ABSTRACT Objective To analyze the electromyographic activity (EMG) and thermographic patterns of the masseter and temporalis muscles and pressure of the orofacial tissues in individuals with intervertebral disc degeneration (IDD). Methods This study had two distinct groups: with IDD (n = 16) and controls (n = 16). EMG at rest, protrusion, right and left laterality, and maximum voluntary contraction were evaluated. Tongue, orbicularis oris, and buccinator muscles pressures were measured by Iowa Oral Performance Instrument. The thermographic patterns were analyzed using infrared thermography. Results Comparisons between groups showed significant differences regarding at rest [right (p = 0.05) and left (p = 0.05) masseter and right temporal (p = 0.05)], orofacial tissue pressure [tongue (p = 0.001), orbicularis oris (p = 0.01), and buccinator (p = 0.0001)], but no significant differences for the thermographic patterns. Conclusion IDD modifies the functionality of the craniomandibular complex, influencing the performance of the stomatognathic system.

Redefining the simplicity of the craniomandibular complex of nightjars: The case of Systellura longirostris (Aves: Caprimulgidae) by means of anatomical network analysis.

To study morphological evolution, itis necessary to combine information from multiple intersecting research fields. Here, we report on the structure of the bony and muscular elements of the craniomandibular complex of birds, highlighting its morphological architecture and complexity (or simplification) in the context of anatomical networks of the Band-winged Nightjar Systellura longirostris (Caprimulgiformes, Caprimulgidae). This species has skull osteology and jaw myology that departs from the general structural plan of the craniomandibular complex of Neornithes and is considered morphologically simple. Our goal is to test if its simplification is also reflected in its anatomical network, particularly in those parameters that measure complexity and to explore if the distribution of the networks in a phylomorphospace is conditioned by their evolutionary history or by convergence. Our results show that S. longirostris clusters with other Strisores and momotids and is segregated from the other bird species analyzed when plotted in the phylomorphospace, as a consequence of convergence in the network parameters. Systellura has a craniomandibular complex consisting of fewer muscles connecting more bones than the model species (e.g., the rock pigeon or the guira cuckoo). In this sense, Systellura is actually more complex regarding the number of integrative bony parts, while its craniomandibular complex is simpler. According to its anatomical network, Systellura also can be interpreted as less complex, particularly compared with other Strisores and taxa that reflect the general structure of the craniomandibular complex in Neornithes.

Differences in craniofacial morphology between platybasic and nonplatybasic patients with velopharyngeal dysfunction and control subjects

This study aimed to identify the characteristics of cranial-base morphology in platybasic and nonplatybasic patients with palatal anomalies and velopharyngeal dysfunction (VPD) compared with control subjects to investigate structural factors related to craniofacial morphology that affect the nasopharyngeal space and may influence velopharyngeal function, and to develop precise treatments for specific patients with VPD. Three hundred eighty-six patients with VPD and various palatal anomalies were studied retrospectively. The control group included 126 healthy patients with normal speech. Lateral cephalometric images assessed craniofacial morphology. Nonplatybasic patients and control subjects had larger SNA, S-Ba-Ptm, and N-Ba-PP angles (in the craniomaxillary complex), and platybasic patients had larger nasopharyngeal ANS-Ptm-Ve and Ba-S-Ptm angles and longer Ve-T and Ve-Ba distances than the nonplatybasic patients. All study patients had larger ANB, Gn-Go-Ar, and PP-MP angles (in the craniomandibular complex). Nonplatybasic patients had smaller Ba-SN angles than platybasic patients and controls because of more acute N-S-Ptm angle. Among the nonplatybasic patients, Ve-T length tended to be shorter (with no significant difference between groups) and located more inferiorly (because of the smallest ANS-Ptm-Ve angle) in relation to the maxilla. Thus, the nasopharynx was narrower horizontally but longer vertically than in patients with platybasia. Cranial-base flexure influences the shape of the skull base and facial-skeletal structure and may alter the pharyngeal space between them. This finding should help improve preoperative planning regarding the effect of the pharyngeal flap height relative to the nasopharynx and oropharynx ratio that affects surgical outcomes, such as resonance and residual VPD. In patients with Class III malocclusion and maxillary constriction, careful planning of presurgical orthodontic treatment is needed in maxillary advancement procedures. Orthodontic and surgical collaboration can help prevent postoperative VPD, especially in platybasic patients.

Why the long beak? Phylogeny, convergence, feeding ecology, and evolutionary allometry shaped the skull of the Giant Cowbird Molothrus oryzivorus (Icteridae).

Cowbirds are a successful group of obligate brood parasites in the Neotropical passerine family Icteridae that offer an interesting model to explore the factors behind the evolution of the bird craniomandibular complex. The Giant Cowbird, Molothrus oryzivorus, stands out from its congeners, among other features, in diet (feeds mostly on fruit, nectar, and arthropods, instead on seeds), its larger body size, and longer, more robust beak with a much broader bony casque than in other cowbirds. In turn, Giant Cowbirds show a remarkable resemblance in these features to the distantly related caciques and oropendolas (some are its breeding hosts). However, the causes behind the latter resemblance and the distinctiveness among cowbirds have not yet been elucidated. We aim to explore the factors involved in the diverging morphology of the Giant Cowbird from its congeners and the convergence with caciques and oropendolas, surveying their skull and lower jaw under an explicit evolutionary framework. Using geometric morphometrics and comparative methods, we assessed the signal of phylogeny, convergence, feeding ecology, and size in skull shape. Our results indicated that evolution of the craniomandibular complex of icterids in general, and of the beak morphology in the Giant Cowbird in particular, are shaped by multiple factors, with phylogeny being largely overridden by changes in size (evolutionary allometry), primarily, and feeding ecology, secondarily. However, the evolution of a broad bony casque in the Giant Cowbird, otherwise a hallmark of caciques and oropendolas, does not appear to have primarily been ruled by evolutionary allometry. Instead, taking into account the unique extreme convergence between Giant Cowbirds and some of its caciques hosts, it might be consequence of selective regimes associated with parasite-host interactions acting on top of other evolutionary processes. This suggests chick mimicry as a reasonable explanation for this peculiar morphology that would require further investigation.

Digest: Taxonomically inclusive and quantitative tests for convergence.

How common is morphological convergence, and can the cause of convergence be traced to simple ecological categories like diet? Tamagnini etal. use phylogenetic comparative methods and simple morphological data from a large number of Carnivora taxa to investigate whether diet causes convergence in their craniomandibular complex. They find that convergence is less prevalent than expected and that this outcome is likely caused by a complex interplay between biomechanics, ecology, and morphology.

Testing the occurrence of convergence in the craniomandibular shape evolution of living carnivorans.

Convergence consists in the independent evolution of similar traits in distantly related species. The mammalian craniomandibular complex constitutes an ideal biological structure to investigate ecomorphological dynamics and the carnivorans, due to their phenotypic variability and ecological flexibility, offer an interesting case study to explore the occurrence of convergent evolution. Here, we applied multiple pattern‐based metrics to test the occurrence of convergence in the craniomandibular shape of extant carnivorans. To this aim, we tested for convergence in many dietary groups and analyzed several cases of carnivoran convergence concerning either ecologically equivalent species or ecologically similar species of different body sizes described in the literature. Our results validate the occurrence of convergence in ecologically equivalent species in a few cases (as well as in the case of giant and red pandas), but almost never support the occurrence of convergent evolution in dietary categories of living carnivorans. Therefore, convergent evolution in this clade appears to be a rare phenomenon. This is probably the consequence of a complex interplay of one‐to‐many, many‐to‐one, and many‐to‐many relationships taking place between ecology, biomechanics, and morphology.

520 A Cone-Beam Computed Tomography Study on the Impact of Bruxism in Craniomandibular Morphology of Adults. Preliminary findings

Abstract Introduction Although bruxism, either during awake and during sleep is still a controversial topic in contemporary Medicine, its prevalence and its putative relationship with several conditions interfering with health and wellbeing make it relevant as a target to be studied in distinct scientific domains. Histological and morphological on the craniomandibular complex (CC) have been documented with different techniques. However, there is a lack of high quality imaging studies showing structural changes among the different anatomical structures therefore leading to a misinterpretation of the real impact of bruxism on such elements.The aim of this clinical retrospective comparative study was to investigate whether there are structural differences on the craniomandibular complex of bruxers in face to non-bruxers evaluated by a cone-beam computed tomohraphy (CBCT). We present the preliminary findings of this still ongoing study. Methods A retrospective analysis of CBCT imaging exams from patients with ages between 18 and 44 years old, were distributed among 1) bruxism group:BG (n=31); 2) Non-bruxism/Control group (n=21). Bruxism diagnosis followed non-instrumental approach suggested by the bruxism consensus 2013. To the craniomorphological evaluation, 3D CBCT SYM Diagnosis protocol was implemented by a calibrated expert at an adequate local with reduced light. Photograpic parameters were analyzed according to standard procedures. Results Female gender prevailed without differences between groups (61,3% in BG and 66,7 in CG; p=0,91). Age of BG was significantly higher than CG (40,1 yo versus 28,4;p=0,002). Mandibular structure as inferred by its shape was significantly higher in BG compared with CG. Conclusion In this preliminary study the CBCT 3D image showed important and significant changes in mandibular structure in bruxers compared with non-bruxers. Support (if any):

Effects of miniplate anchored Herbst appliance on skeletal, dental and masticatory structures of the craniomandibular apparatus: A finite element study

To analyze the stress distribution in the hard and soft tissue structures of craniomandibular complex during mandibular advancement with miniplate anchored rigid fixed functional appliance (FFA) using Finite Element Analysis (FEA). The virtual model consisting of all the maxillofacial bones (up to calvaria), the mandible and temporomandibular joint (TMJ) was generated using the volumetric data from pre-treatment CBCT-scan of a growing patient. The masticatory muscles, other soft tissues, Herbst appliance and plate geometry were modelled mathematically. Force vectors simulating muscle contraction at rest and advanced mandibular positions, with protraction force of 8N were applied. The final model was imported into ANSYS for analysis after assigning material properties. The maximum von Mises stress of 11.69MPa and 11.96MPa magnitude was observed in the region of pterygoid plates and at the bone-miniplate interface respectively, with the mandibular advancement of 7mm. Stress patterns were also noted at the condylar neck. The stress values observed in the medial and lateral pterygoid muscles were of 10.42MPa and 4.16MPa magnitude, respectively. Stress was noted in the bucco-cervical region of the upper posterior teeth, but negligible change was seen on the lower anterior teeth and periodontal ligament. Miniplate Anchored Herbst Appliance brought about Class II skeletal correction in growing children as it was accompanied by minimal changes in the inclination of the lower incisors. Soft tissue structures like pterygoid muscles and discal ligaments exhibited increased stress whereas masseter muscle displayed reduction in stresses.

The cranio-mandibular complex of the nightjar Systellura longirostris (Aves, Caprimulgiformes): functional relationship between osteology, myology and feeding

Here we address the morphology of the cranial musculoskeletal in the South American Band-winged nightjar (Systellura longirostris, Caprimulgiformes, Aves) with the focus upon in how the mouth closure and opening mechanism is. Bony characters such as the thinness of the interorbital septum and the reduction of the postorbital process co-assist the location of large eyes, although correlations between eye size brain mass and body mass revealed that the Band-winged nightjar’s eye is bigger than expected. The reduction of the processus orbitalis of the os quadratum would allow the great mouth opening given by a large maxillary protraction. Systellura longirostris shows a zona flexoria intramandibularis with marked reduction in bone ossification that helps to the lateral opening of the jaws. In Systellura longirostris, the m. pseudotemporalis profundus, m. adductor mandibulae externus superficialis, and m. adductor mandibulae externus medialis are absent. The adductor muscles represent 66.614% of the total mandibular muscle mass. Physiological Cross Sectional Area (PCSA) values of the adductor muscles are high and the fibers are relatively long compared to other zoophagous birds, another condition that favors adduction. The m. adductor mandibulae externus profundus is the largest jaw muscle regarding its mass but its osteological correlate on the neurocranium, the fossa temporalis, is absent. In the absence of some muscles in charge of the bill closing, an elastic instability model for jaw closing is proposed.

Functional morphology of the cranio-mandibular complex of the Guira cuckoo (Aves).

The cranio-mandibular complex is an important structure involved in food capture and processing. Its morphology is related to the nature of the food item. Jaw muscles enable the motion of this complex and their study is essential for functional and evolutionary analysis. The present study compares available behavioral and dietary data obtained from the literature with novel results from functional morphological analyses of the cranio-mandibular complex of the Guira cuckoo (Guira guira) to understand its relationship with the zoophagous trophic habit of this species. The bite force was estimated based on muscle dissections, measurements of the physiological cross-sectional area, and biomechanical modeling of the skull. The results were compared with the available functional morphological data for other birds. The standardized bite force of G. guira is higher than predicted for exclusively zoophagous birds, but lower than for granivorous and/or omnivorous birds. Guira guira possesses the generalized jaw muscular system of neognathous birds, but some features can be related to its trophic habit. The external adductor muscles act mainly during food item processing and multiple aspects of this muscle group are interpreted to increase bite force, that is, their high values of muscle mass, their mechanical advantage (MA), and their perpendicular orientation when the beak is closed. The m. depressor mandibulae and the m. pterygoideus dorsalis et ventralis are interpreted to prioritize speed of action (low MA values), being most important during prey capture. The supposed ecological significance of these traits is the potential to widen the range of prey size that can be processed and the possibility of rapidly capturing agile prey through changes in the leverage of the muscles involved in opening and closing of the bill. This contributes to the trophic versatility of the species and its ability to thrive in different habitats, including urban areas.

Effect of mouthguards on impact to the craniomandibular complex.

The aim of this study was to investigate the effect of wearing a mouthguard and teeth-clenching on impact to the head and temporomandibular joint (TMJ) during a blow to the jaw. A custom-made mouthguard was fabricated for five participants. A 4.1-N impact load was applied to the chin with a pendulum. Two acceleration sensors were attached to the forehead and left TMJ. The amplitudes and durations of the accelerations were obtained under five conditions: mouth-open without mouthguard; light teeth-clenching without mouthguard; maximum voluntary clenching (MVC) without mouthguard; mouth-open with mouthguard and MVC with mouthguard. Wearing a mouthguard led to significant decreases in the amplitude (mouth-open with mouthguard vs mouth-open without mouthguard, P = 0.035 at forehead, P = 0.022 at TMJ) and duration (mouth-open with mouthguard vs mouth-open without mouthguard, P = 0.043 at forehead, not significant at TMJ). Similarly, teeth-clenching caused significant decreases in the amplitude (mouth-open without mouthguard vs MVC without mouthguard, P = 0.024 at forehead, P = 0.025 at TMJ) and duration (mouth-open without mouthguard vs MVC without mouthguard, P = 0.033 at forehead, not significant at TMJ). Furthermore, wearing a mouthguard in itself provided an impact reduction effect similar to the combination of teeth-clenching and wearing a mouthguard. Wearing a mouthguard and/or teeth-clenching reduced the impact to the head and TMJ during a blow to the jaw. However, it should be noted that the findings are the results from a small impact load to the jaw.

Functional implications of craniomandibular morphology in African mole-rats (Rodentia: Bathyergidae)

African mole-rats are subterranean rodents from the family Bathyergidae. The family consists of six genera, five of which (Cryptomys, Fukomys, Georychus, Heliophobius and Heterocephalus) are chisel-tooth diggers, meaning they dig underground using procumbent incisors. The remaining genus of mole-rat (Bathyergus) is a scratch digger, which digs using its forelimbs. Chisel-tooth digging is thought to have evolved to enable exploitation of harder soils. It was hypothesized that to dig successfully using incisors, chisel-tooth digging mole-rats will have a craniomandibular complex that is better able to achieve a large bite force and wide gape compared with scratch digging mole-rats. Linear measurements of morphological characteristics associated with bite force and gape were measured in several chisel-tooth digging and scratch digging mole-rats. Chisel-tooth diggers have increased jaw and condyle lengths relative to their size (characteristics associated with larger gape). They also have relatively wider and taller skulls (characteristics associated with larger bite force). The mechanical advantage of three masticatory muscles of each specimen was also calculated. The mechanical advantage of the temporalis muscle was significantly larger in chisel-tooth digging mole-rats than scratch digging genus. The results demonstrate that chisel-tooth digging bathyergids have a craniomandibular morphology that is better able to facilitate high bite force and wide gape than scratch digging mole-rats.

Morphological Constraints in the Craniomandibular Complex of Chisel‐tooth Digging Mole‐rats

African mole-rats are subterranean rodents from the family Bathyergidae, which consists of six genera, five of which (Cryptomys, Fukomys, Georychus, Heliophobius and Heterocephalus) are chisel-toot...

Histomorphology of the mandibular condylar cartilage in greater galagos (Otolemur spp.)

The functional morphology of the primate craniomandibular complex and temporomandibular joint (TMJ) components is frequently discussed in terms of gross skeletal structure. At the histomorphologic level, however, the TMJ has only been studied in Old World anthropoids. The present study is designed to describe the microanatomy of the condylar cartilage of the TMJ in two closely related species of greater galago: the exudativorous Otolemur crassicaudatus and the frugivorous O. garnettii. TMJs with intact joint capsules were harvested from adult, cadaveric specimens of these species (four O. crassicaudatus and five O. garnettii). The samples were decalcified, processed for paraffin sectioning, and sectioned at 10-18 microm in the coronal plane. The samples were then stained with hematoxylin/eosin, Gomori trichrome, and Alcian blue, and examined with a photomicroscope. Generally, condylar cartilage in O. crassicaudatus was thickest both laterally and centrally, while O. garnettii had the relatively thickest cartilage laterally. Both species displayed a superficial articular zone, a middle proliferative zone, and a deeply located hypertrophic zone in the condylar cartilage. O. crassicaudatus typically had the greatest cell density in each of these zones. In addition, O. crassicaudatus had focal concentrations of Alcian blue laterally and centrally, while O. garnettii had the greatest reactivity in the central portion only. These results suggest that O. crassicaudatus may be specialized to resist greater compressive force at the TMJ condylar cartilage in specific regions of the mandibular condyle.

Occlusal stabilization appliance: evaluation of its efficacy in the treatment of temporomandibular disorders

Occlusal stabilization appliances or splints are the most widely employed method for treatment of temporomandibular disorders (TMD). Magnetic Resonance Imaging (MRI) is the most indicated imaging modality to evaluate the components of the temporomandibular joint (TMJ). Forty patients with signs and symptoms of temporomandibular disorders were treated with splints for a mean period of 12 months, comprising regular semimonthly follow-ups. After stabilization of the clinical status, occlusal adjustments and MRI evaluation were performed. It was concluded that the success of this kind of treatment are related to the total (70%) or partial improvement (22.5%) of painful symptomatology and to the functional reestablishment of the craniomandibular complex. The MRI allowed evaluation and also the conclusion that the splints provide conditions for the organism to develop means to resist to the temporomandibular disorders by means of elimination of several etiologic factors. Moreover, after treatment the patients are able to cope with disc displacements with larger or smaller tolerance.

The effect of growth hormone therapy on mandibular and cranial base development in children treated with total body irradiation.

The aim of the present investigation was to study craniomandibular development during growth hormone (GH) therapy in nine girls and one boy, aged between 7.3 and 16 years, who exhibited pronounced growth reduction after total body irradiation (TBI) and bone marrow transplantation (BMT). Age- and sex-matched healthy children with normal dentofacial development constituted the control material. The investigation data were based on measurements made on lateral skull radiographs taken at the start and, on average, 6 months after cessation of GH treatment. The control group comprised similar longitudinal cephalographic records. The results showed that GH therapy in patients who exhibited growth retardation after TBI and BMT had only a minor effect on cranial base dimensions, probably due to the fact that the development of this area is completed at a relatively early age. The effect of GH treatment on mandibular growth was very obvious. The dimensional increase of the mandibular variables in the patients was equivalent to, or in some cases even exceeded, that of the controls. In relation to basion, the mandibular condyles were displaced in a backward/upward direction in the patient group. Displacement in the opposite direction was recorded in the controls. It seems likely that the development seen in the patients is a reflection of a normalization of the condyle-fossa relationship made possible by enhanced condylar growth. This change should be advantageous for the function of the craniomandibular complex.

A magnetic appliance for treatment of snoring patients with and without obstructive sleep apnea

The aim of this intraindividual study was to investigate the effects of an intraoral magnetic appliance on snoring, daytime sleepiness, and blood oxygen saturation, as well as to analyze the effects on the craniomandibular complex and investigate the response of the device to craniofacial structure. Twenty-five male patients (mean age 54.1 years, SD 11.44) with handicapping snoring or obstructed sleep apnea (OSAS) participated in the study. The appliance consisted of a maxillary and a mandibular occlusal acrylic splint. In each splint, four cylindrical neodymium-iron-boron magnets were embedded and oriented to produce intermaxillary forces that pulled the mandible forward. After a treatment period of 6 months, questionnaires were used for registration of the patients' subjective rating of daytime sleepiness and their close relatives' opinions about the snoring. The treatment effects on the temporomandibular joint were evaluated, according to Helkimos' anamnestic and dysfunctional index, and nightly registration of blood oxygen saturation was performed before and after 6 months of treatment. The effects on craniofacial skeletal and soft tissue profiles were analyzed cephalometrically. All patients easily accepted the magnetic appliance. The main symptoms, snoring and daytime sleepiness, decreased significantly when the magnet appliance was inserted ( p = 0.0001 and p = 0.0002, respectively). The blood oxygen saturation during sleep was also improved ( p = 0.012). The treatment had no aberrant effects on the temporomandibular joint status. The appliance made the mandible rotate downward and backward, mean 7.8°, and this rotation mostly camouflaged the forward movement of the mandible. There was no significant influence on the hyoid bone position, but the hypopharyngeal airway space increased, the tongue base was lowered, and the contact between the tongue and soft palate was reduced significantly.(Am J Orthod Dentofacial Orthop 1998;113:144-055)