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PubMed2001

Dental and skeletal changes associated with long-term mandibular advancement.

STUDY OBJECTIVES: Little is known of the possible dental or skeletal side 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 33-74 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 degrees 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.

Adult↗
PubMed1998

Prosthodontic and surgical management of a patient with an osteoma of the temporomandibular joint.

Osteomas of the temporomandibular joint are rare. This article presents a case report delineating treatment of a partially edentulous patient using a team approach for an osteoma originating from the anterolateral aspect of the glenoid. The tumor was diagnosed with the aid of a panoramic radiograph and a computerized axial tomograph. Interim prostheses with anterior teeth and posterior teeth with nonanatomic occlusal surfaces were fabricated before surgery. After surgical excision of the osteoma, the interim prostheses were periodically adjusted as the mandibular condyle gradually shifted into the space that was previously occupied by the tumor. Final removable prostheses were fabricated after the condyle had stopped shifting.

Aged↗
PubMed2005

A comparative analysis of temporomandibular joint morphology in the African apes.

A number of researchers have suggested a functional relationship between dietary variation and temporomandibular joint (TMJ) morphology, yet few studies have evaluated TMJ form in the African apes. In this study, I compare TMJ morphology in adults and during ontogeny in Gorilla (G.g. beringei, G.g. graueri, and G.g. gorilla) and Pan (P. paniscus, P. troglodytes troglodytes, P.t. schweinfurthii, and P.t. verus). I test two hypotheses: first, compared to all other African apes, G.g. beringei exhibits TMJ morphologies that would be predicted for a primate that consumes a diet comprised primarily of moderately to very tough, leafy vegetation; and second, all gorillas exhibit the same predicted morphologies compared to Pan. Compared to all adult African apes, G.g. beringei has higher rami and condyles positioned further above the occlusal plane of the mandible, relative to jaw length. Thus, mountain gorillas have the potential to generate relatively more muscle force, more evenly distribute occlusal forces along the postcanine teeth, and generate relatively greater jaw adductor moment. G.g. beringei also exhibits relatively wider mandibular condyles, suggesting these folivorous apes are able to resist relatively greater compressive loads along the lateral and/or medial aspect of the condyle. All gorillas likewise exhibit these same shape differences compared to Pan. These morphological responses are the predicted consequences of intensification of folivory and, as such, provide support for functional hypotheses linking these TMJ morphologies to degree of folivory. The African apes to not, however, demonstrate a systematic pattern of divergence in relative condylar area as a function of intensification of folivory. The ontogenetic trajectories for gorillas are significantly elevated above those of Pan, and to a lesser but still significant degree, mountain gorillas similarly deviate from lowland gorillas (G.g. gorilla and G.g. graueri). Thus, adult shape differences in ramal and condylar heights do not result from the simple extrapolation of common growth allometries relative to jaw length. As such, they are suggestive of an adaptive shift towards a tougher, more folivorous diet. However, the allometric patterning for condylar area and condylar width does not systematically conform to predictions based on dietary specialization. Thus, while differences in condylar shapes may confer functional advantages both during growth and as adults, there is no evidence to suggest selection for altered condylar proportions, independent of the effects of changes in jaw size.

Africa↗
PubMed1996

The human mandibular canal arises from three separate canals innervating different tooth groups.

The purpose of this study was to describe the prenatal formation of the human mandibular canal. Since bony canals develop in prenatal life around the nerve paths, it was assumed that the canal pattern could reflect the pattern of innervation of the dentition. Mapping of this early canal pattern does not appear to have been undertaken before. The material consisted of anthropological mandibles from the National Institute of Anthropology and History, Mexico City. A total of 302 human hemimandibles from the latter half of the prenatal period was investigated. The length, measured from the mental symphysis to the mandibular condyle, ranged from 28 to 60 mm. The dento-alveolar maturity was classified in two stages according to the appearance of alveolar sockets of deciduous and first permanent molars. The mandibles were radiographed with guttapercha points inserted into the canal openings (foramina) on the lingual surfaces of the mandibular rami. The study showed that the canal to the incisors appeared first, followed by the canal to the primary molars, and last by the one or more canals to the first permanent molars. In the most mature group, three different canals always occurred in each hemimandible. The canals were directed from the lingual surface of the mandibular ramus toward the different tooth groups. The inferior alveolar nerve presumably occurs in the mandible as three individual nerve paths originating at different stages of development. It is suggested that rapid prenatal growth and remodeling in the ramus region result in a gradual coalescence of the canal entrances that is obvious at birth. It is hypothesized that the pattern of tooth agenesis within the three groups of teeth is related to the three separate paths of innervation of the dentition.

Dentition↗
PubMed1977

[Geometric-mathematical analysis of transition errors in the articulator and their practical effects].

In a computerized program based on the conditions in the Dentatus articulator, those errors were calculated and graphically represented which resulted from the inaccurate registration of the following parameters: Sagittal and caudal distance of incisal point to condyle axis, condyle dise put into relation to 2 mm laterotrusion of a molar point. In both the frontal and the horizontal plane, the individual parameters led to differently great errors which influenced the working and the balancing sides differently. The greatest errors occur when changing the angle of the inclination of the mandibular condyle path and the sagittal and caudal distance of incisal point to condyle axis. Errors of several tenths of a millimeter in the frontal plane are potential disturbing factors.

Cephalometry↗
PubMed2002

Thin-plate spline graphical analysis of the mandible in mandibular prognathism.

The chin cup has been used to treat skeletal mandibular prognathism in growing patients for 200 years. The pull on the orthopedic-force chin cup is oriented along a line from the mandibular symphysis to the mandibular condyle. Various levels of success have been reported with this restraining device. The vertical chin cup produces strong vertical compression stress on the maxillary molar regions when the direction of traction is 20 degrees more vertical than the chin-condyle line. This treatment strategy may prevent relapse due to counter-clockwise rotation of the mandible. In this report, we describe a new strategy for using chin-cup therapy involving thin-plate spline (TPS) analysis of lateral cephalometric roentgenograms to visualize transformation of the mandible. The actual sites of mandibular skeletal change are not detectable with conventional cephalometric analysis. A case of mandibular prognathism treated with a chin cup and a case of dental Class III malocclusion without orthodontic treatment are described. The case analysis illustrates that specific patterns of mandibular transformation are associated with Class III malocclusion with or without orthopedic therapy, and that visualization of these deformations is feasible using TPS graphical analysis.

Cephalometry↗
PubMed1983

Effect of maxillary osteotomy on subsequent craniofacial growth in adolescent monkeys.

LeFort I osteotomy was performed on seven adolescent Macaca fascicularis monkeys to study its effect on the subsequent dentocraniofacial growth. Eight adolescent monkeys were used as controls. Tantalum implants were inserted at predetermined areas in certain craniofacial bones of all monkeys. For stereometric cephalometry, implants were placed in both the left and right sides of the facial bones. Lateral cephalometric radiographs of all monkeys were taken prior to and immediately after metallic implant placement, immediately after maxillary osteotomy, and thereafter every 4 weeks during the postsurgical period. At least two cephalograms were taken on each occasion, one with the teeth in occlusion and the other with mouth wide open. The latter was used to view the mandibular condyle adequately. These findings suggest that the maxillary osteotomy did disturb the vertical growth of the maxilla at the PNS and retarded the horizontal growth at the premaxilla. The anterior growth of the maxilla and mandible and the vertical growth of the face were substantially reduced. The most interesting finding was also a reduction of the mandibular growth in all of its dimensions. The rate and the amount of reduced anterior mandibular growth were found to be coordinated with the anterior maxillary growth which resulted in all animals showing a normal overjet, overbite, and occlusion throughout the postsurgical observation period.

Animals↗
PubMed1999

[Current problems in the diagnosis and treatment of injuries to the temporomandibular joint].

Complex examination of 2103 patients with temporomandibular joint (TMJ) injuries was carried out. This examination included contrast arthrotomography, computed tomography (CT) and MR tomography of the TMJ. It gas been established, that in mandibular condyle fractures not only bone structures of the TMJ, but also soft tissue ones (the articular disk and capsular-ligamentous apparatus) are being injured. Our investigation has shown that condylar fractures in the region of condylar base and neck are combined with the injuries of the articular disk and capsular-ligamentous apparatus in 54.1 +/- 5.4% cases, mandibular head fractures with its dislocation--in 100%. The term "TMJ injuries" reflecting the injuries of bone and soft tissue structures of the TMJ has been introduced. The classification of TMJ injuries including TMJ contusion, mandibular dislocations, condylar and glenoid fossa fractures, the injuries of the articular disk and capsular-ligamentous apparatus has been developed. Distant results of traditional methods of treatment used in TMJ trauma have been studied and the necessity of the restoring of correct relation: glenoid fossa --articular disk--mandibular head--has been shown. The method of TMJ reconstruction consisting in the restoration of TMJ bone structures and the articular disk and capsular-ligamentous apparatus has been developed.

Arthroplasty↗
PubMed1994

CT of intact but nonfunctioning temporomandibular joints following temporal bone fracture.

Six patients were examined by CT following head trauma, with bleeding from the ear and trismus. The mandibular condyles were normal and MRI in two patients demonstrated a normally located meniscus. An unilateral comminuted temporal bone fracture (TBF) with multiple fracture lines and one or more fragments detached from the petrous bone was demonstrated by CT in every patient. On physical examination there was trismus, inability to chew and local pain in the temporomandibular joint (TMJ) without tenderness and swelling. Measurements of vertical and horizontal mandibular movement unequivocally demonstrated TMJ malfunction in comparison with 10 controls. The malfunction was presumably due to instability of the fractured petrous bone, base of the TMJ. Immobilising one TMJ results in blocking of both joints. Clinical improvement in 6-8 months and absence of symptoms of joint derangement on repeated physical examination were thought to be explained by restored petrous bone stability following healing of the fractures. The phenomenon of trismus following TBF with normal TMJ is rare and not yet reported.

Adolescent↗
PubMed1987

Facial growth subsequent to Le Fort I osteotomies in adolescent monkeys.

The study goal was to assess qualitatively and quantitatively the craniofacial adaptations following total maxillary osteotomy with and without mandibular autorotation. Six adolescent female Macaca fascicularis monkeys were randomly divided into two surgical groups, and eight others served control. Prior to surgery, metallic implants were inserted in the anterior part of the cranial base, on opposite sides of craniofacial sutures, and in multiple sites of the maxilla and mandible. Group I animals underwent a Le Fort I advancement of 4 mm, while Group II animals had a 5-mm advancement and a 2.5-mm impaction. Lateral cephalometric head-films were taken at monthly intervals for a total follow-up of 12 months after surgery. At least two cephalograms were taken on each occasion, one with the teeth in occlusion and the other with the mouth wide open. The latter was used to ascertain accurately the outline of the mandibular condyle. Cephalometric superimposition methods were used to quantify the growth changes. The findings indicated that the growth changes in the maxilla and mandible were related to the extent of injury caused by maxillary surgery. The largest increments and rates of growth were observed respectively in the control animals, Group I animals (anterior maxillary repositioning), and Group II animals (anterior and superior maxillary repositioning). The most interesting finding was that mandibular growth pattern followed maxillary growth pattern in both experimental groups, and the immediate postsurgical occlusion in Class II molar relationship was maintained with increased overjet in both experimental groups throughout the postsurgical observation period.

Animals↗
PubMed2006

[Aneurysmal bone cyst of the mandible: a case report].

Aneurysmal bone cyst is a benign lesion that is more commonly seen in long bones and the vertebra. Its occurrence in the craniofacial region is rare. A nine-year-old boy presented with a well-demarcated, painless, fixed mass, 3 x 3 cm in size, in the left preauricular region, with no fluctuation or crepitation. Computed tomography showed a lesion in the left mandibular ramus with a fluid-fluid level, extending to the mandibular condyle, with erosion to the adjacent cortex. Total curettage was performed via a transoral approach under general anesthesia. Histopathologic diagnosis was made as an aneurysmal bone cyst. No recurrence or complication were seen during a follow-up period of four years.

Bone Cysts, Aneurysmal↗
PubMed1996

[Neurologic examinations for facial nerve damage in surgically treated mandibular collum fractures].

Transcranial magnetic stimulation is a new method for objective evaluation of the facial nerve without constraints for the patient. By the first time, especially cortical lesions can be detected objectively. Using this method, a permanent disturbance of the ramus marginalis mandibularis after operative treatment of fractures of the mandibular condyle could be certainly excluded. Therefore, because of the clear presentation and the possibility of enlargement, the deep submandibular approach, using a correct operative technique, can be strictly recommended.

Electromagnetic Fields↗
PubMedDate not supplied

[Facial nerve paralysis and mandibular fracture].

The authors describe three cases of peripheral facial nerve paralysis in patients with a mandibular fracture. In two cases, in which the onset of palsy was uncertain, the facial nerve injury was contralateral to the fractured side. Topodiagnostic tests showed neural damage at the third intrapetrosal portion and at the genicular ganglion. In one of the two patients tomography revealed a fracture line through the anterio-superior wall of the external auditory canal homolateral to the facial palsy. In the third subject palsy set in immediately after the trauma and was ipsilateral to the mandibular fracture; the facial lesion was localized at the genicular ganglion. In the first two cases, functional recovery was spontaneous (40 and 0 days after the trauma respectively). In the third subject, the nerve was decompressed surgically with a complete functional recovery two months later. The functional and clinical findings of these three cases show that a contralateral facial palsy secondary to a mandibular fracture resolves spontaneously while the traumatic displacement of the mandibular condyle may determine a temporal bone fracture sometimes followed by a lesion in the intratemporal portion of the facial nerve. An event such as the latter may delay functional recovery and thus warrant surgery such as in cases of Bell's palsy.

Accidental Falls↗
PubMed1992

Biomechanical model of the human mandible: a hypothesis involving stabilizing activity of the superior belly of lateral pterygoid muscle.

A new biomechanical analog for the human mandible is proposed. The biomechanics of the human mandible can be explained by a simple support model, where muscular forces are produced by the masseter, medial pterygoid, temporal, and superior lateral pterygoid muscle components, and reaction forces are produced by the occlusal surfaces and condyle. All forces are resolved into components orthogonal and parallel to the temporal articular plane (articular eminence). In this model, one component of muscular forces is parallel to the temporal articular plane. The influence of the inclination of the occlusal plane, the inclination of the temporal articular plane, the position of the resultant of the occlusal reactions, and the relative contribution of the different jaw elevator muscles on the parallel and orthogonal components are evaluated according to a computer model of the system. The muscular force parallel to the temporal articular plane may be produced by the superior lateral pterygoid muscle, which during clenching acts as a stabilizer of the mandibular condyle to prevent posterior dislocation and compression of nonarticular tissues.

Biomechanical Phenomena↗
PubMed1991

Tissue responses to degenerative changes in the temporomandibular joint: a review.

The articular cartilage covering of the mandibular condyle and the articular eminence, as well as the tissue of the articular disc, may be affected by degenerative changes associated with osteoarthrosis. Degenerative changes of cartilage alter its physical properties and, as a result, affect its ability to withstand compressive and shearing stresses. Increased friction between the articular surfaces may impair joint movement and may elicit compensatory or pathologic responses of the cartilage and the adjacent tissues, such as capsule and ligaments, synovial membrane, subchondral bone, and associated musculature. In this review, these structural changes are described and related to common signs and symptoms of craniomandibular dysfunction, such as clicking, locking and instability, pain and tenderness, restricted ranges of mandibular motion, crepitation, deformity, muscle wasting, and changes of occlusion.

Adaptation, Biological↗
PubMed1981

Scleroderma: oral manifestations.

An oral clinical and radiologic study of twenty-one patients suffering from scleroderma revealed that in one half of the patients the blood sedimentation rate and the antinuclear factor were elevated. When both these laboratory findings were present at the same time, they proved to be well correlated. The majority of the patients had limited mouth opening. Gross jawbone changes affecting the mandibular condyle, coronoid process, and posterior part of the ascending ramus occurred in four patients. There was no correlation in these four patients with regard to the bone changes and clinical and laboratory findings or to age and duration of illness. Widening of the periodontal ligament space, as measured in a meticulous manner, was a feature in all twenty-one patients and in all teeth.

Adult↗
PubMed1986

Injury to the glenoid fossa.

An illustrated case of fracture through the confines of the glenoid fossa by the mandibular condyle is presented. The mechanism of injury and postinjury sequelae of this rarely reported but frequently suspected occurrence are discussed and a treatment rationale proposed. The key to the diagnosis of this entity is an awareness of vector forces directed to the region of the glenoid fossa with or without evidence of subcondylar fracture.

Accidents, Traffic↗
PubMed1989

Relationships between the size and spatial morphology of human masseter and medial pterygoid muscles, the craniofacial skeleton, and jaw biomechanics.

The relationship between human craniofacial morphology and the biomechanical efficiency of bite force generation in widely varying muscular and skeletal types is unknown. To address this problem, we selected 22 subjects with different facial morphologies and used magnetic resonance imaging, cephalometric radiography, and data from dental casts to reconstruct their craniofacial tissues in three dimensions. Conventional cephalometric analyses were carried out, and the cross-sectional sizes of the masseter and medial pterygoid muscles were measured from reconstituted sections. The potential abilities of the muscles to generate bite forces at the molar teeth and mandibular condyles were calculated according to static equilibrium theory using muscle, first molar, and condylar moment arms. On average, the masseter muscle was about 66% larger in cross section than the medial pterygoid and was inclined more anteriorly relative to the functional occlusal plane. There was a significant positive correlation (P less than 0.01) between the cross-sectional areas of the masseter and medial pterygoid muscles (r = 0.75) and between the bizygomatic arch width and masseter cross-sectional area (r = 0.56) and medial pterygoid cross-sectional area (r = 0.69). The masseter muscle was always a more efficient producer of vertically oriented bite force than the medial pterygoid. Putative bite force from the medial pterygoid muscle alone correlated positively with mandibular length and inversely with upper face height. When muscle and tooth moment arms were considered together, a system efficient at producing force on the first molar was statistically associated with a face having a large intergonial width, small intercondylar width, narrow dental arch, forward maxilla, and forward mandible. There was no significant correlation between muscle cross-sectional areas and their respective putative bite forces. This suggests that there is no simple relationship between the tension-generating capacity of the muscles and their mechanical efficiency as described by their spatial arrangement. The study shows that in a modern human population so many combinations of biomechanically relevant variables are possible that subjects cannot easily be placed into ideal or nonideal categories for producing molar force. Our findings also confirm the impression that similar bite-force efficiencies can be found in subjects with disparate facial features.

Adult↗