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At least 19 recordsLinked to original sources
PubMed1987

Morphometrical observations on the mandible of five strains of rabbits and strain identification using mandible measurements.

In order to clarify the relationships between five strains of rabbits and to identify the strains, principal component and discriminant analyses were carried out using 12 mandibular measurements of three inbred strains (JW-NIBS/Y (JW/Y), NW-NIBS/Y (NW/Y) and Dutch-NIBS/Y (D/Y)) and two outbred strains (JW-NIBS (JW) and NW-NIBS (NW] which were maintained at the Nippon Institute for Biological Science. The results obtained were as follows. (1) Principal component analysis revealed that in the males the mandible of JW was the largest but with considerable variation. D/Y was the smallest of all strains examined. The mandibles of NW and NW/Y were similar to the JW mandibles but had a shape which was shorter and higher. In the females the mandible of NW was the largest of all strains and, as in the males, D/Y was the smallest and JW varied markedly. (2) Discriminant analysis showed the probability of erroneous discrimination to be 14.8% (34/229) when the inbred and outbred strains were combined. In both sexes erroneous discrimination mostly occurred between NW and NW/Y, which have the same origin, and between JW and NW, which have a common ancestor. However, when the inbreds and outbreds were identified separately by discriminant analysis, the probability of erroneous discrimination was low in both cases (4.5% (5/112) and 7.7% (9/117) respectively). These results indicate that strain differences are found in the size and shape of rabbit mandibles and that mandible analysis is effective for strain identification of laboratory rabbits.

Animals↗
PubMed1990

[Asymmetry of the mandible. Study of 386 mandibles in vitro].

The aim of this study was to investigate the existence of asymmetry or not between the right and left side of the mandible. Three hundred eighty six edentulous dry mandibles were measured. The results showed that: --Asymmetry was found in a percentage of 82.26% between the two rami of the mandible, with the right ramus being smaller than the left (45.66%). --Asymmetry was found in a percentage of 82% between the two parts of the body of the mandible, with the right part being smaller than the left (51.91%). --Asymmetry was found in a percentage of 82.2% between the two sides of the mandible, with the right side being smaller than the left (47.4%). --Asymmetry was found in a percentage of 82.2% between the two sides of the arch, formed of the rounded lower border of the mandible, with the right side being smaller than the left (49.2%).

Facial Asymmetry↗
PubMed2000

Oblique lateral cephalometric radiographs of the mandible in implantology: usefulness and reproducibility of the technique in quantitative densitometric measurements of the mandible in vivo.

In the literature intraoral periapical radiographs are commonly used for densitometric measurements of the mandible with implants. These films give detailed information of the implant and the surrounding bone. However, in extreme mandibular atrophy it can be difficult to obtain intraoral radiographs of adequate diagnostic quality. Extraoral Oblique Lateral Cephalometric Radiographs (OLCRs) can then be the alternative: reproducible images of large parts of the mandible can be obtained. In vitro, the results of densitometry using periapical films and OLCRs were shown to be similar. The present study aims to determine the measurement error of densitometry with OLCRs in vivo. In 16 patients (group I) with atrophic mandible and implants, duplicate OLCRs of one side of the jaw were obtained. The error of measurement for the densitometric measurements of the mandibular bone was 5.5%. The use of a specially developed correction program to compensate for undesired variations in the projection of the soft tissues of the face (tongue, lips, cheek and neck) on the radiographs resulted in a 40% reduction of that measurement error to 3.5%. This remaining error is mainly brought about by an imperfect repositioning of the patient when the duplicate OLCRs are obtained. The error caused by the image acquisition, processing and measurement is less than 1%. Deliberate variation up to 7.5 degrees of the horizontal angle wherein the OLCRs are made, results in a large error of measurement of 13.5% (group II: 17 patients). To reduce this variation the additional soft tissue correction program is unsuitable. It is concluded from this study that the described radiographic and image analysis technique is a promising tool for prospective densitometric studies of the mandible with or without implants. Especially in mandibles with bone grafts and implants, substantial changes in the graft can occur. The described technique may be particularly valuable in analyzing these changes.

Aluminum↗
PubMed1993

Morphometric profiles of the mandible of SMXA recombinant inbred strains of mice and strain identification on the basis of mandible measurements.

SMXA recombinant inbred (RI) strains were derived from the F2 generation of a cross between two progenitor inbred strains, A/J and SM/J, which differ considerably with respect to many characters. In order to determine the morphometric profiles of the mandible of SMXA RI strains and to identify these strains, principal component and discriminant analyses (mandible analysis) were carried out using 11 mandible measurements. Principal component analysis revealed that the mandibles of each strain have their own characteristic size and shape. The RI strains, however, were roughly divided into 15 groups based on the morphometric profile of their mandibles. Discriminant analysis showed the probability of erroneous discrimination to be 6.49% (20/308) for the males and 8.06% (27/335) for the females. In both sexes, most of the erroneous discrimination (13 in the male, 17 in the female) occurred between RI strains having comparatively similar morphometric profiles. This suggested that all of the SMXA RI strains examined could be regarded as genetically homogeneous within each strain.

Animals↗
PubMed1989

[Standard measurements, elasticity values and tensile strength behavior of the human mandible, a contribution to the biomechanics of the mandible--I].

This paper is intended to help to characterize the physiological behavior of compact bone structure, so that realistic account can be taken of it when performing finite element (FE) analysis with the aim of solving biomechanical problems. In addition, further knowledge about the complex mechanical behavior of bone structure is provided. In accordance with anthropometric considerations, 13 mandibles have been measured, and a standard mandible defined for use in representative model calculations. In 4 mandibles (fully dentulous, partly dentulous, edentulous), orthotropic mechanical behavior of the fresh bone was determined experimentally. A comparison was also made with published data, as well as our own unpublished data obtained in other bone structures. Orthotropic behavior of the bone structure was confirmed. The material data of the individual bone structure vary considerably, but remain within a certain range. The proportion of the direction-dependent data is, however, almost constant. Our data correspond well with published data, although a direct comparison with the data of the mandible was not possible. A comparison of the data with those from the lower and upper extremities shows significant differences in rigidity, Young's modulus, and extension. A gradation can be found--starting with a maximum--that reveals the following order: mandible, upper extremity, lower extremity. In the case of extension, this order is reversed.

Biomechanical Phenomena↗
PubMed1984

The mandible, an overhanging mechanically suspended structure. Considerations on the system of attachment and servo-command of the mandible.

The mandible, owing to its form, surrounding muscles and "position" in the craniofacial unit can be assimilated to an overhanging mechanically suspended structure. The hypothesis, according to which the temporomandibular joints would be submitted to pressure during mastication should be abandoned on the basis of anatomical and clinical findings. Furthermore, this hypothesis is in disagreement with the results of simulation on a physicomathematical model of the mandible. Accordingly, it is reasonable to assume that the mandible is a suspended structure and that the elevator muscles of mastication, especially the masseter and medial pterygoid (together forming the mandibular sling), and probably also the anterior belly of the temporalis muscle play a twin role in the suspension of this bone. These muscles obviously command the movement of closure. They also constitute the suspensory apparatus of the mandible and, by mechanical computation, should display a certain degree of elasticity and undergo most of the mechanical constraints developed during mastication. One can also consider the cranio-facio-mandibulo-hyoid group as a suspended structure. The comparison of this type of system to the basic principles of servo-robotics allows to understand that such a structure is capable of extremely precise movements in all spatial planes with a minimum of effort.

Biomechanical Phenomena↗
PubMed1977

Biologic laws governing functions of muscles that move the mandible. Part III. Speed of closure--manipulation of the mandible.

The character of the occlusal surfaces of teeth programs the functions of muscles that move the mandible and imposes specifications upon the dentist within which he must work in manipulating the patient's mandible. If he exceeds those specifications, protective responses that inhibit his efforts are elicited in the patient's musculature. A knowledge of the laws governing functions of the muscles that move the mandible enables the dentist to acquire mandibular-manipulation skills necessary for diagnosis and effective occlusal treatment. A model in which the dentist visualizes the patient, the patient's protective reflexes, the components of the patient's gnathostomatic system, and himself as four independent personalities participating in the jaw manipulation is a useful tool in acquiring mandibular-manipulation skills. This article is Part III of a series presented in four parts on the "Biologic Laws Governing Functions of Muscles That Move the Mandible."

Biomechanical Phenomena↗
PubMed1976

The flared mandible sign of the flail mandible.

A useful radiographic finding is described for the diagnosis of a flail mandible. The flail mandible removes forward support for the tongue, which may result in airway obstruction. Immediate radiographic diagnosis allows quick surgical correction of the fractured mandible and relief of the obstruction, decreasing the time during which an endotracheal or tracheostomy tube is needed to keep the airway open.

Airway Obstruction↗
PubMed1990

[Mechanical characteristics of the human mandible and study of in vivo behavior of compact bone tissue, a contribution to the description of biomechanics of the mandible--II].

On the basis of the investigation of fresh bone in Part I, results are presented that show the influence of ageing, location and direction on the characteristics of the mandible. A comparison with the results of the earlier report, reveals the extent of degradation. The test results of 56 specimens of the left halves of the mandibles L 01, 02 and 03 indicate a so-called self-splint effect within the bony cross-section in the vicinity of structure possibly diseased or attenuated areas. Investigation of the "in-vivo" behavior of the compact bone was performed on the thigh bone of a freshly slaughtered cow. The influence of the loading velocity on Young's modulus was evaluated, and revealed an elastic and a viscid component, and that an asymptotic limit applies. It was also shown that the loading velocity of 0.2 mm/min, which was used for the tests, provides values very close to the asymptotic limit. Changes in condition, associated with progressive demineralisation and drying out of the bone tissue during the preparation of the specimens have an influence on Young's modulus. Specimens were tested under dry and wet conditions, and a variation of 20% caused by moisture was found. In general, the stiffness of dry specimens is higher than that of specimens in a physiological condition.

Animals↗
PubMed1989

[Anatomy of the atrophic mandible. 1. The location of the mandibular canal in the atrophic mandible].

43 atrophic left hemimandibles were divided by 6 saw cuts made between the mental foramen and the third molar to analyze the location of the mandibular canal. Mandibles were classified by the severity of alveolar absorption using Atwood's classification and changes in the distances of the mandibular canal from the superior and inferior borders of the mandibular body were correlated wit the degree of atrophy. Measurements were obtained with a digitizer and a computer and results were analyzed statistically. The following statistically significant observations were made: The distance of the mandibular canal to the external lingua and buccal cortical layers did not change with increasing atrophy, but remained remarkably constant. By contrast, highly significant changes in the distance of the mandibular body were found to be present. These were more pronounced at the superior than at the inferior border. The changes seen were consistently most severe at the level of the first molar. Prior to surgical interventions involving an atrophic mandible the location of the mandibular canal should invariably be identified by imaging techniques such as orthopantomography, telemetric X-rays, tomographies, CT and MRI, if indicated, in order to avoid injuries of the inferior alveloar nerve and preclude forensic consequences.

Aged↗
PubMed2000

[Management of comminuted and open fractures of the mandible and fractures in atrophic mandibles with titanium mesh].

Miniplate osteosynthesis is a standard method for the surgical treatment of mandible fractures today. Apart from easy handling, in the majority of cases it also ensures adequate fracture stability. The treatment of fractures of very atrophic mandibles as well as mandibular defects and comminuted fractures with miniplates and rigid plates is often difficult or only possible to an inadequate extent. Titanium mesh has proved successful for the treatment of such fractures. Compared with conventional miniplates this mesh is outstanding for its considerably higher stability due to its given geometry. The titanium mesh can be adapted and screwed individually in any situation, in contrast to miniplates and rigid plates. As a result, complications such as fracture gap infections and pseudoarthrosis can be avoided to a great extent.

Adult↗
PubMed1987

[Aggressive fibrous dysplasia of the mandible. Resection of the lower portion of the mandible].

Report of a case of swelling monostotic fibrous dysplasia in the left part of the mandible in a girl 8 years old. Two rapid recurrences after total curettage require the sus periostal resection of the left part of the mandible, without bone graft. Total recovery with 6 years follow up, with good cosmetic and functional result because of bone regeneration and growth stimulation by orthesis.

Bone Diseases, Developmental↗
PubMedDate not supplied

Reconstruction of the mandible: use of combined homologous mandible and autologous bone.

Loss of portions of the mandible as a result of trauma or cancer surgery poses a difficult problem in reconstruction. Experience in the use of the mandibular homograft combined with autologous bone and bone marrow in 26 patients is reviewed. It is evident that this method of reconstruction has many advantages but is a failure in patients who have received radiation therapy to the recipient site.

Adult↗
PubMed1990

[A study of developmental changes of Indian mandibles concerning development of weight, height, thickness and length of the mandible].

A total of 230 mandibles were classified into 7 groups 8 stages according to eruption phase, observing developmental changes from unerupted stage (Group A) to permanent dentition (Group G) 1. Development from Group A to deciduous dentition completion stage (Group C) was classified into 3 types. 1) Regarding height of mandibular ramus, height and weight of mandibular body, the increase from Group B where the deciduous central incisor erupts to Group C is greater that from Group A-B (type a). 2) As to coronoid process height, length of mandibular body, mandibular length and mandibular ramus width, equal increases were seen between Group A-B and B-C (type b). 3) Chin height and thickness of the mandibular body developed suddenly with the eruption of the deciduous central incisors. The increase is greater in Group A-B (type c). 2. They are classified according to size proportion in unerupted stage as compared to entire size. The classification are: 42%-33% (smaller), 50%-45% (medium), 70%-50% (bigger). 1) Type a is small at Group A and developed steadily after Group C. Development is greater, about 2.3-3 times. 3) Type b at Group A is larger than type a. It continuously developed after Group C. The developmental rate is about 2 times except the coronoid process height. 3) Type c is large at Group A. No development occurred after D1 stage when first molars erupt. Developmental rate is 1.4-1.85 times and smallest of the 3 types. 3. Developmental quantity: 1) Regarding total increase; The height of the mandibular ramus, the height of the mandibular ramus and coronoid process showed about 28-32 mm increase Group C accounted for 55%, Group C-D2 14%-17%, Group D2-G 30%-27% of the developmental increase. The mandibular ramus width showed increases of 14.43mm (74% at D1 stage) and subsequent increase was 7% between each group, showing equal increases. 2) Chin and mandibular ramus height showed increases of 14 mm. At Group C, development in chin height accounted for 67%. The mandibular body width increased 4.0mm-6.0mm at the foramen in m2/m2 and 6/6 portions. It reached 82%-100% in D1 stage. 3) An increase in mandibular body length and mandibular length was 50mm and 32mm, reaching 73% of the entire developmental amount by D1 stage.

Adolescent↗
PubMed1988

Movement and function of mandible--a simplified mechano-morphological model of mandible.

It is an obvious fact that the shape of mandibles and its change are much concerned with the force vector of mastication muscles. In reference to the shape of mentum, however, it is yet inexplicable up to the present that the human mentum is such toughly shaped as being bearable against the force induced by mastication. In this paper, the authors show their three-dimensional mechanics model for the analysis in strength and they indicate that this model is suitable to explaining the shape.

Humans↗