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At least 973 records · Page 54Linked to original sources
PubMed2000

Comparisons of bone volumes and densities relating to osseointegrated implants in microvascularly reconstructed mandibles: a study of cadaveric radius and fibula bones.

The study was designed to compare the dimensions and densities of two frequently used bone donor sites with regard to placement of endosseous dental implants in microvascularly reconstructed mandibles. A total of 40 radii and of 40 fibulae were investigated. Fifty two percent of the fibulae had adequate bone volume for the positioning of four 10 mm implants, while this figure was 55% for the radii. After using the 'double barrel' technique the placement of four 10 mm implants succeeded in 87% of all the fibulae. Due to the lack of bone length required, this special technique was not possible in the radii investigated. Cortical thickness and density of bone were higher in the radii when compared with the fibulae. In each bone the central and distal parts presented the highest values of cortical thickness and density. Although the radius offers enough substantial bone for implant placement in some cases this cannot be used for clinical purpose, as only hemicortical grafts can be obtained. Otherwise the resulting donor site morbidity would be intolerable. In conclusion, our results support the clinical experience that the fibula is today's 'work horse' donor site for reconstruction of the mandible.

Aged↗
PubMed2000

Development of a static simulator of the mandible.

Our aim was to build and assess a static mandibular simulator capable of reproducing various masticatory exercises as closely as possible to physiological situations. Unlike existing devices that reproduce a small number of exercises and of muscular bundles, our simulator is able to reproduce all types of effort in the sagittal plane and integrates eleven muscular groups considered by the majority of authors as being the most important in mastication. The value of our simulator arises from its ability to replicate the external forces (including muscular traction, intra-articular reaction and resultant forces applied to the mandible) as determined in vivo during previous studies. The importance of such a versatile simulator, in addition to enabling study of the mechanical behaviour of the mandible, is that it greatly enhances evaluation of a possible mathematical model by means of finite element analysis. Stages of the development and evaluation of this device are described.

Computer Simulation↗
PubMed2002

[Sonography in callus distraction of the hypoplastic mandible].

OBJECTIVES: Since the early 1990's when callus distraction of hypoplastic mandibles was developed, surgeons have been looking for a reliable method to monitor distraction treatment. X-rays films resulted in insufficient quality of images of low calcified structures and are only of little support in follow-up. Therefore, a standardised protocol using ultrasound was introduced. METHODS: 24 patients were included (aged 4 - 29 years with hemifacial microsomy [19], mandibulary micrognathia [5]), 20 intraoral (Howmedica-Leibinger/Mühlheim) and 9 extraoral distractors (Normed/Tuttlingen). Standard procedures for intra- and extraoral distraction were carried out and all postsurgical treatment steps were monitored by ultrasound. RESULTS: The mineralisation of the neocallus shows the following sequence: echogenic dots, needles directed along the distraction direction, bands, plaques, and modulation of the neocompacta. Additional therapeutically relevant questions of distraction distance, inflammation or occurrence of pus, arising during treatment were answered by sonography. Distance measurements could be performed reliably. CAT scan and MRI cannot be carried out because of metal artefacts. X-ray pictures like orthopantomogram and Clementschisch projection cannot show the early mineralisation and do not allow an exact distance measurement. CONCLUSIONS: Sonography is a effective, method to investigate the callus field without using X-rays and supports monitoring and decision making in distraction treatment of hypoplastic mandibles.

Adolescent↗
PubMed1997

[Ultrasound of segment distraction and callus formation in reconstruction of the mandible. Value of surgical ultrasound of callus distraction of vascularized ilial crest transplants and mandibular segments in a previously irradiated area].

PURPOSE: B-scan ultrasonography (US) was applied in patients subjected to callus distraction for bone formation at the interface of mandibular segments and vascularised bone grafts. METHODS: This study consisted of 7 patients requiring further surgical augmentation to allow for prosthetic treatment. All patients had been preoperatively irradiated percutaneously in the region of the primary oral squamous cell carcinoma up to an isodose of 60-75.5 Gy. Ablative surgery was then performed, including discontinuity resection of the mandible. Vascularised iliac crest grafts had been chosen due to poor healing conditions in the irradiated recipient site. For callus distraction, a distraction device was inserted in both the mandibular segment and the bone graft. Subsequently, osteotomy was performed, and distracting forces were applied to the segments. For US, a small-part applicator was used (7.5 MHz). RESULTS: US gives a true estimation of the distraction length, actually achieved at the time of investigation. The applicator can be easily adjusted to the area of interest. Application is safe and easy, the results are reliable, and the procedure can be carried out without affecting the hygiene of the wound after surgical intervention. In addition, US enables the supervising surgeon to detect zones of calcification in the area of callus distraction at an earlier point than can be detected by standard x-ray documentation, thus facilitating control of the therapy. CONCLUSION: US is highly recommended for routine application in callus distraction of the mandible. X-ray documentation is a "must".

Bone Transplantation↗
PubMed1995

The fate of the osteotomized free radial forearm osteocutaneous flap in mandible reconstruction.

The radial forearm osteocutaneous free flap has become a standard method of mandible reconstruction. In order to improve the contour of the reconstructed jaw in large resections, especially the anterior defect, the radial forearm bone graft needs to be osteotomized. The bone graft is nourished by small branches of the radial artery via the fascial connections between the skin flap and bone. The effect of the osteotomy, fixation devices, and the angulation of the bone segment on bone viability and eventual bone healing is not known. Forty-two radial forearm osteocutaneous flaps were used for composite mandible reconstruction. In 25 patients, the bone graft required osteotomy to achieve contour, of which 16 required single osteotomy and nine required double osteotomy. In a remaining 17 cases, no osteotomy was performed. Only those patients who had at least a 1-year follow-up were included in this study. The proportion of patients who achieved bone union was similar for both groups (i.e. osteotomy vs. nonosteotomy). Performing osteotomies on the segment of the radius in free osteocutaneous transfers is safe, and it allows for more flexibility in reconstruction, to achieve a natural-appearing jaw.

Adult↗
PubMed1993

Sonographic measurement of the fetal mandible: standards for normal pregnancy.

Measurements of the fetal mandible were made on 204 women with uncomplicated pregnancies and reliable gestational dates. The measurements were made in the sonographic plane, which included the fetal mandible and the hypopharynx. The antero-posterior and transverse jaw measurements increased with gestational age (p < 0.0001), and correlated well with both the biparietal diameter and femur length (p < 0.0001). Measurements were technically more difficult to obtain during the late third trimester. These standards for fetal jaw measurement may be useful in the sonographic identification of micrognathia.

Embryonic and Fetal Development↗
PubMed1989

[Sonographic detection of osteodestruction of the mandible].

32 patients with osseous destruction of the mandible were examined sonographically. The results were compared with those of plain radiographs. In 30 patients, discontinuation of the cortex was clearly evident. Sonography could detect osteolytic lesions in the corpus region, in the angle and on the buccal side of the rami of the mandible. 2 cases of osteodestruction on the lingual side could not be seen.

Aged↗
PubMed2001

Postsurgical growth changes in the mandible of adolescents with vertical maxillary excess growth pattern.

This case-control study investigates the effects of superior maxillary repositioning by LeFort I osteotomy on adolescent mandibular growth. A total of 15 growing patients (average age, 12.8 years) with vertical maxillary excess who had undergone maxillary surgery were compared with matched untreated control subjects. Lateral cephalograms were evaluated and superimposed to describe the presurgical (1.6 years), surgical, and postsurgical (4.0 years) changes. During the presurgical period, comparisons of traditional measures and mandibular modeling changes showed no significant differences between the 2 groups. During surgery, the maxilla was impacted approximately 3 mm anteriorly and 1 mm posteriorly, which caused a 3.2 degrees autorotation of the mandible. During the postsurgical period, there was no change in the vertical growth pattern of the surgical patients, with the vertical facial heights increasing the same as the control subjects and the mandible rotating backwards. Although there was no inhibition of mandibular growth in the patients postsurgically, there was a decrease in horizontal maxillary growth compared with control subjects. There were clear postsurgical changes in the mandibular modeling and condylar growth, which were indicative of adaptive compensations for surgical mandibular repositioning and autorotation. It is concluded that early maxillary impaction does not normalize or inhibit the vertical maxillary excess growth pattern; mandibular modeling and condylar growth undergo adaptive changes in response to repositioning.

Adaptation, Physiological↗
PubMedDate not supplied

Intra-operative acute leg ischaemia after free fibula flap harvest for mandible reconstruction.

Osteosarcomas of the cranial bones need a large surgical radical resection. The best option to reconstruct mandible defect after resection is the free fibula flap. In our patient an acute ischaemic leg occurred just after the free fibula flap harvest for mandible reconstruction. The abnormal distribution of the calf arteries leads to catastrophic consequences. The peroneal artery could be the main dominant artery of the leg in a small number of patients. We reported an extremely rare case of "peronea magna", described in less than 0.2% of the global population. A careful pre-operative workup of the calf vessels is required in all the patients who need free fibula flap harvest.

Adult↗
PubMed2000

Prolonged mandibular hypomobility patient with a "square mandible" configuration with coronoid process and angle hyperplasia.

The objective of this study was the surgical management of chronic severe mandibular hypomobility patients associated with square mandible morphology with coronoid process and angle hyperplasia, and one-year follow-up data is reported. Ten patients were studied. All patients were female and had a history of gradual severe jaw hypomobility. Clinical findings were similar to those of a "closed lock" patient. However, the facial appearance in these patients showed a characteristic square mandible facial configuration. Coronoid process thickening and overgrowth of the mandibular angle was evident in the radiographic findings. Diagnostic imaging scarcely depicted any disk derangement, but a severely limited jaw opening was noted in spite of acceptable excursive jaw movements. Bilateral coronoidotomy or coronoidectomy was done initially, and then masseter muscle stripping via the intraoral approach. After successful reduction of jaw hypomobility, a selective mandibular anglectomy was completed. Physical therapy began within three to five days after the surgery. Postoperatively, all patients were questioned about their jaw function and their subjective assessment of the treatment. Interincisal jaw opening was recorded with a ruler marked in millimeters. Bilateral coronoidotomy or coronoidectomy and masseter muscle stripping were done for all patients; the mandibular anglectomy was performed in seven of the cases at 13 sites. Simultaneous TMJ surgery was done on three joints for three patients. Most patients reported improvement of jaw function, and the patients' subjective assessment revealed an average satisfaction rate of 74.6%. A preoperative mean jaw opening distance of 25.6 mm increased to 36.6 mm postoperatively at a one-year follow-up (p < 0.05). The conclusion was that surgical intervention is indicated when nonsurgical treatment is unsuccessful. Etiology is unknown, but masseter and temporal muscle contracture associated with mandibular coronoid and angle hyperplasia may be a strong component of the pathophysiology.

Adolescent↗
PubMed2003

Mandible and maxilla bone mineral density and threshold analysis studies by pQCT in two edentulous women receiving pamidronate.

The mandible and maxilla of two edentulous women, treated during 25 weeks with oral pamidronate, were monitored by peripheral quantitative tomography (pQCT). Whole bone volumetric mineral density failed to show meaningful variations after treatment. However, an analysis of separated cortical and medullar areas disclosed focal bone loss at the right mandible cortex of patient #1 and at the left maxilla cortex of patient #2. These and other bone sub-regions were further studied by clustering the internal sites with a different degree of bone mineral density, resorting to the mineral threshold analysis provided by the system. Where bone loss was detected, it corresponded to increased loss of the most osteopenic sites, while medium and high-density portions tended to remain unchanged within the region. There were no significant variations in all other regions, or alternatively, minor losses at osteopenic sites were compensated by an increase at high-density portions. Hence, the pQCT system allowed monitoring volumetric bone mineral density at particular sites of interest, discriminating variations at portions with a dissimilar degree of bone volume. Further studies should confirm whether pamidronate exerts a protective effect on sub-regions with previous medium and high degrees of bone mineralization, as suggested by our present findings.

Bone Demineralization, Pathologic↗
PubMed2000

Immediate free flap mandibular reconstruction in osteosarcoma of the mandible in childhood.

Mandibular osteogenic sarcoma (OS) is a very rare entity in childhood. Adequate surgical rejection with a wide margin of normal tissue is the mainstay of treatment of this site, while the role of adjuvant chemotherapy remains uncertain. A case is presented of a 15 1/2-year-old male with a huge OS of the mandible. The boy underwent surgical resection of the mandible with immediate fibula free flap reconstruction and is alive and free of disease 6 1/2 years following unitial diagnosis. This case suggests that immediate bone reconstitution with vascularized grafts have good functional and morphological results for osteosarcoma of the lower jaw.

Adolescent↗
PubMed1989

Disposition of cervical vertebrae, atlanto-axial joint, hyoid and mandible during x-ray laryngoscopy.

Ten healthy volunteers underwent direct laryngoscopy using topical anaesthesia and a curved Macintosh laryngoscope blade. A lateral x-ray was performed during laryngoscopy in a standard intubating position. In this position the lower neck was relatively straight and increasing curvature occurred from the mid cervical spine upwards. Extension at the atlanto-axial joint was probably near maximum; this has implications for conditions associated with laxity of this joint. The position of the mandible was influenced by the direction of pull on the laryngoscope handle. The hyoid was drawn forward and its body tilted downwards so as to lie halfway between the lower border of the mandible and the glottis. The relative length of epiglottis projecting above the hyoid was variable.

Adult↗
PubMed1992

Postnatal width changes in the internal structures of the human mandible: a longitudinal three-dimensional cephalometric study using implants.

This paper presents case-specific quantitative evidence of the systematic lateral displacement of metallic implants in the mandibles of treated and untreated human subjects between the ages of 8.5 and 15.5 years. This evidence appears to be consistent with the inference of small, but systematic increases in distance between the internal structures of the two sides of the osseous mandible during growth. Such a conclusion, however, is inconsistent with traditional beliefs that the internal structures of the mandibular symphysis fuse at the midline during the first post-natal year and remain dimensionally constant thereafter. We recently published evidence of statistically significant transverse displacement of metallic implants in the mandibular body region for 12 of 28 subjects for whom longitudinal data were available. Of the twelve subjects for whom statistically significant changes were observed, widening occurred in eleven cases and narrowing in one. Matching data are now available on concurrent ramus changes for 22 of the same 28 subjects, including 11 of the 12 for whom statistically significant width changes had previously been noted in the body region. In eight of these 11 subjects, statistically significant widening in the ramus region was also observed. No subject had statistically significant widening in the ramus region without also having statistically significant widening in the body region. No subject had statistically significant trans-ramus narrowing.

Adolescent↗
PubMed2006

Influence of sex hormone disturbances on the internal structure of the mandible in newborn mice.

It has not yet been clarified how sex hormones affect craniofacial bone development immediately after birth. The purpose of this study was to examine the effects of sex hormone deficiency on craniofacial bone development immediately after birth, in terms of the internal structure of the mandible in newborn mice with orchiectomy (ORX) and ovariectomy (OVX). ORX, OVX and a sham-operation were performed on 40 five-day-old C57BL/6J mice. Eight weeks after surgery, each mandible was subjected to histomorphometric analysis of trabecular (Tr) and cortical (Ct) bone mineral density (BMD) by peripheral quantitative computed tomography (pQCT). In the experimental groups, a significant reduction in BMD was found in comparison with the control groups. In histomorphometric analysis, the number of tartrate-resistant acid phosphatase (TRAP)-positive cells in the condyle and the thickness of the condylar cartilage layer was significantly greater in the experimental mice than in the controls. Trabecular bone volume of the condyle measured on azocarmine-aniline blue (AZAN) sections was significantly less in the experimental mice than in the controls. These results indicate that mandibular growth is inhibited by sex hormone disturbances and the relevant internal structures changed. The findings show that sex hormones are one of the key determinants of mandibular growth and development immediately after birth.

Acid Phosphatase↗
PubMed1985

Genetics of mandible form in the mouse.

The underlying determination of phenotypic variability and covariability is described for 14 traits that define the morphological size and shape of the mature mouse mandible. Variability is partitioned into components due to direct additive and dominance genetic effects, indirect maternal additive genetic effects, genetic covariance between direct additive and indirect maternal additive effects and common and residual environmental effects. Multivariate analyses of the dimensionality of genetic variability indicate several complex and independent genetic components underlie the morphological form of the mandible. The multidimensional nature of the genetic components suggests a complex picture with regard to the consequences of selection on mandibular form.

Analysis of Variance↗
PubMed1988

Genetic divergence in mandible form in relation to molecular divergence in inbred mouse strains.

Genetic divergence in the form of the mandible is examined in ten inbred strains of mice. Several univariate and multivariate genetic distance estimates are given for the morphological data and these estimates are compared to measures of genealogical and molecular divergence. Highly significant divergence occurs among the ten strains in all 11 mandible traits considered individually and simultaneously. Genealogical relationship among strains is highly correlated with genetic divergence in single locus molecular traits. However, the concordance between genealogical relationship and multivariate genetic divergence in morphology is much more complex. Whether there is a significant correlation between morphological divergence and genealogy depends upon the method of analysis and the particular genetic distance statistic being employed.

Animals↗
PubMed1986

Reconstruction of the atrophic mandible.

Because atrophy of the jaws in edentulous patients is a major health problem, how best to reconstruct the atrophic mandible is a dilemma that frequently confronts the medical and dental professions. After loss of the natural dentition, the reduction of the residual ridges is progressive, irreversible, and cumulative. The cause and pathogenesis of mandibular atrophy is discussed. In the evaluation of a patient, the amount of residual bone at the symphysis should be measured on the lateral cephalometric radiograph as an aid to treatment planning. This measurement allows the degree of atrophy to be classified as minor, moderate, or severe. The current techniques to rehabilitate the edentulous mandible, including relative and absolute heightening techniques and implants, are reviewed with illustrative examples. A modification of a previous absolute heightening osteotomy technique utilizing pedicle bone flaps, is presented.

Adult↗