Comparative Study of the Mechanical Resistance of 2 Separate Plates and 2 Overlaid Plates Used in the Fixation of the Mandibular Condyle: An In Vitro Study

Purpose: The objective of this study was to carry out a comparative evaluation of the mechanical resistance of 2 rigid internal fixation techniques for fractures of the mandibular condyle using miniplates.Materials and Methods: Fort), polyurethane resin replicas of human hemimandibles were used. The hemimandibles were sectioned to simulate a high subcondylar fracture and then stabilized with 2 fixing techniques using 2.0-mm system plates and screws. The fixation techniques were 2 separate 4-hole plates with 8 screws, and 2 overlaid 4-hole plates with 4 screws. Each system was submitted to load tests, with the application of the load in mediolateral and anteroposterior directions in an Instron 4411 universal assay machine (Instron, Norwood, MA).Results: Load values and peak displacement were measured. Means and standard deviations were evaluated by analysis of variance (P < .05) and Tukey tests, in which it was verified that the anteroposterior peak load value was affected by the arrangement of the plates on the models, although no differences were observed between the groups for the mediolateral peak load. The arrangement of the plates did not have any influence on peak displacement. Similarly, the final value of the mediolateral load was not affected by the arrangement of the plates on the model.Conclusion: The experimental model with 2 separate plates was statistically superior to the model with 2 overlaid plates only in relation to anteroposterior peak load. Despite showing superiority in mediolateral peak load and peak displacement, there was no statistical difference between the groups for these parameters. (C) 2009 American Association of Oral and Maxillofacial Surgeons

Conservative condylectomy for management of osteochondroma of the mandibular condyle

Osteochondroma is one of the most common benign tumors of the skeleton. This tumor is rare in the craniofacial region, with the most common sites of occurrence being the coronoid process of the mandible and the mandibular condyle. Traditionally, the treatments of these lesions include total condylectomy or local resection of the lesion. Conservative condylectomy procedure with reshaping of the remaining condylar neck and repositioning of the articular disk has been suggested. This article aimed to describe a 35-year-old woman with osteochondroma in the left mandibular condyle who was treated by conservative condylectomy. The patient has been free of recurrence for 2 years, showing good aesthetic and functional stability. Copyright © 2013 by Mutaz B. Habal, MD.

Using Conservative Condylectomy for Management of a Large Osteochondroma of the Mandibular Condyle With 6-Year Follow- up

Osteochondroma is a hamartomatous proliferation of cartilaginous tissue, which is the most common benign tumor of the long bones, but is relatively rare in the maxillofacial region. Most cases of mandibular condylar osteochondroma manifest with facial asymmetry or malocclusion with limited temporomandibular joint movements. Several approaches for management of this lesion have been proposed, as conservative condylectomy technique. This procedure has been suggested a valid approach to minimize facial asymmetry, contributing to the recovery of occlusion associated with no local tumor recurrence, and without condylar reconstruction procedure. Therefore, this article aims to describe a clinical report of a true osteochondroma of the mandibular condyle in a 35-year-old patient who was successfully treated using conservative condylectomy procedure.

Treatment of severe facial asymmetry secondary to osteochondroma of the mandibular condyle: case report

Osteochondroma (OC) is the most common benign tumor of long bones. However it is rarely found in the facial skeleton, being the coronoid process and mandibular condyle the most affected sites in this region. It basically consists in bone growth covered by cartilage. The etiology is still controversial: neoplastic, developmental, reparative and traumatic origins have been discussed in literature. The treatments of these lesions include total condylectomy or local resection of the lesion. This paper aims to report a case of a patient with history of trauma and possible fracture of the mandibular condyle in childhood, which in youth developed dentofacial deformity with severe facial asymmetry. The treatment consisted of resection of lesion both with maxillary and mandibular osteotomies associated with graft from the iliac crest bone. Actually, the patient is with a favorable aesthetic, without functional deficit and absence of lesion’s recurrence.

Effects of estrogen deficiency combined with chronic alcohol consumption on rat mandibular condyle

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Changes in cells's secretory organelles and extracellular matrix during endochondral ossification in the mandibular condyle of the growing rat

The mandibular condyle from 20-day-old rats was examined in the electron microscope with particular attention to intracellular secretory granules and extracellular matrix. Moreover, type II collagen was localized by an immunoperoxidase method. The condyle has been divided into five layers: (1) the most superficial, articular layer, (2) polymorphic cell layer, (3) flattened cell layer, (4) upper hypertrophic, and (5) lower hypertrophic cell layers. In the articular layer, the cells seldom divide, but in the polymorphic layer and upper part of the flattened cell layer, mitosis gives rise to new cells. In these layers, cells produce two types of secretory granules, usually in distinct stacks of the Golgi apparatus; type a, cylindrical granules, in which 300-nm-long threads are packed in bundles which appear lucent after formaldehyde fixation; and type b, spherical granules loaded with short, dotted filaments. The matrix is composed of thick banded lucent fibrils in a loose feltwork of short, dotted filaments. The cells arising from mitosis undergo endochondral differentiation, which begins in the lower part of the flattened cell layer and is completed in the upper hypertrophic cell layer; it is followed by gradual cell degeneration in the lower hypertrophic cell layer. The cells produce two main types of secretory granules: type b as above; and type c, ovoid granules containing 300-nm-long threads associated with short, dotted filaments. A possibly different secretory granule, type d, dense and cigar-shaped, is also produced. The matrix is composed of thin banded fibrils in a dense feltwork. In the matrix of the superficial layers, the lucency of the fibrils indicated that they were composed of collagen I, whereas the lucency of the cylindrical secretory granules suggested that they transported collagen I precursors to the matrix. Moreover, the use of ruthenium red indicated that the feltwork was composed of proteoglycan; the dotted filaments packed in spherical granules were similar to, and presumably the source of, the matrix feltwork. The superficial layers did not contain collagen II and were collectively referred to as perichondrium. In the deep layers, the ovoid secretory granules displayed collagen II antigenicity and were likely to transport precursors of this collagen to the matrix, where it appeared in the thin banded fibrils. That these granules also carried proteoglycan to the matrix was suggested by their content of short dotted filaments. Thus the deep layers contained collagen II and proteoglycan as in cartilage; they were collectively referred to as the hyaline cartilage region.

Efeito da deficiência estrogênica associada ao consumo de álcool no côndilo mandibular de ratas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise da posição mandibular através de diferentes métodos de localização

Pós-graduação em Odontologia - FOA

Avaliação do comportamento mecânico de três diferentes tipos de osteossíntese em fratura de côndilo mandibular: análise por elementos finitos 3D

Pós-graduação em Odontologia - FOAR

Finite element evaluation of three methods of stable fixation of condyle base fractures

The surgical treatment of mandibular condyle fractures currently offers several possibilities for stable internal fixation. In this study, a finite element model evaluation was performed of three different methods for osteosynthesis of low subcondylar fractures: (1) two four-hole straight plates, (2) one seven-hole lambda plate, and (3) one four-hole trapezoidal plate. The finite element model evaluation considered a load applied to the first molar on the contralateral side to the fracture. Results showed that, although the three methods are capable of withstanding functional loading, the lambda plate displayed a more homogeneous stress distribution for both osteosynthesis material and bone and may be a better method when single-plate fixation is the option.

Estabilidade sagital da condiloplastia associada à cirurgia ortognática para o tratamento do osteocondroma mandibular

The aim of this study was to evaluate the stability of the conservative condylectomy technique and articular disc repositioning as the surgical treatment approach for management of mandibular condylar osteochondroma, with appropriate Orthognathic surgery. Fifteen patients (12 females and 3 males), average age of 32.3 years (range, 13 to 56 years), with unilateral active osteochondroma of the mandibular condyle were analyzed. All patients underwent conservative condylectomy, recontouring of the remaining condylar neck stump and articular disc repositioned and indicated orthognatic surgical procedures. Average post surgical follow-up was 19 months. Each patient's lateral cephalograms were traced at 3 intervals (presurgery, immediate post surgery and long-term follow-up). Immediate after surgery the oclusal plane angle decreased -2.8 ± 4.5o, the maxillomandibular complex rotated counter-clockwise with advancement at menton 5.3 ± 5.6 mm, pogonion 5.0 ± 5.1 mm, B point 3.4 ± 4.2 mm and A point 1.0 ± 1.5 mm. The long-term follow-up showed significant changes in overbite (-0.6 ± 0.5 mm) and SNGoMe (0,93° ± 1,53°). Horizontally and vertically small instabilities occurred in Me (-1.21 ± 1.94 mm) and PNS (-1.48 ± 1.67 mm) respectively. The treatment protocol studied produced counterclockwise rotation and maxillofacial mandibular advancement. The long-term follow-up showed solid dental and skeletal stability with horizontal instability of Me and PNS in the vertical direction.

Effect of alendronate on endochondral ossification in mandibular condyles of growing rats

The replacement of the calcified cartilage by bone tissue during the endochondral ossification of the mandibular condyle is dependent of the resorbing activity of osteoclats. After partial resorption, calcified cartilage septa are covered by a primary bone matrix secreted by osteoblasts. Osteoadherin (OSAD) is a small proteoglycan present in bone matrix but absent in cartilage during the endochondral ossification. The aim of this study was to analyze the effect of alendronate, a drug known to inhibit bone resorption by osteoclasts, on the endochondral ossification of the mandibular condyle of young rats, by evaluating the distribution of osteoclasts and the presence of OSAD in the bone matrix deposited. Wistar newborn rats (n = 45) received daily injections of alendronate (n = 27) or sterile saline solution as control (n = 18) from the day of birth until the ages of 4, 14 and 30 days. At the days mentioned, the mandibular condyles were collected and processed for transmission electron microscopy analysis. Specimens were also submitted to tartrate resistant acid phosphatase (TRAP) histochemistry and ultrastructural immunodetection of OSAD. Alendronate treatment did not impede the recruitment and fusion of osteoclasts at the ossification zone during condyle growth, but they presented inactivated phenotype. The trabeculae at the ossification area consisted of cartilage matrix covered by a layer of primary bone matrix that was immunopositive to OSAD at all time points studied. Apparently, alendronate impeded the removal of calcified cartilage and maturation of bone trabeculae in the mandibular ramus, while in controls they occurred normally. These findings highlight for giving attention to the potential side-effects of bisphosphonates administered to young patients once it may represent a risk of disturbing maxillofacial development.

Auriculo-condylar syndrome: mapping of a first locus and evidence for genetic heterogeneity

Auriculo-condylar syndrome (ACS), an autosomal dominant disorder of first and second pharyngeal arches, is characterized by malformed ears (`question mark ears`), prominent cheeks, microstomia, abnormal temporomandibular joint, and mandibular condyle hypoplasia. Penetrance seems to be complete, but there is high inter-and intra-familial phenotypic variation, with no evidence of genetic heterogeneity. We herein describe a new multigeneration family with 11 affected individuals (F1), in whom we confirm intra-familial clinical variability. Facial asymmetry, a clinical feature not highlighted in other ACS reports, was highly prevalent among the patients reported here. The gene responsible for ACS is still unknown and its identification will certainly contribute to the understanding of human craniofacial development. No chromosomal rearrangements have been associated with ACS, thus mapping and positional cloning is the best approach to identify this disease gene. To map the ACS gene, we conducted linkage analysis in two large ACS families, F1 and F2 (F2; reported elsewhere). Through segregation analysis, we first excluded three known loci associated with disorders of first and second pharyngeal arches (Treacher Collins syndrome, oculo-auriculo-vertebral spectrum, and Townes-Brocks syndrome). Next, we performed a wide genome search and we observed evidence of linkage to 1p21.1-q23.3 in F2 (LOD max 3.01 at theta = 0). Interestingly, this locus was not linked to the phenotype segregating in F1. Therefore, our results led to the mapping of a first locus of ACS (ACS1) and also showed evidence for genetic heterogeneity, suggesting that there are at least two loci responsible for this phenotype.

Reorganizacao do processo condilar da articulacao temporomandibular apos condilectomia unilateral, em camundongos tratados com zidovudina (AZT)

In order to analyze the reorganization of the condylar process after unilateral condylectomy in animals which have received AZT, 30 albino mice, 30 days old were used. The condylectomized animals were divided in two groups, one have received distilled water and the other AZT, orally during 10 days. After 5, 10, 15, 30 and 45 days of the surgery the animals of both groups were sacrificed, their heads removed and fixed in 10% formalin. After decalcification the pieces received histological routine treatment to be included in paraffin. The slices were stained by hematoxylin/eosin method. The analysis of results showed that: 1. the condylar repair is similar on both groups; 2. the results reaffirm those found in the literature, that the articulation after condylectomy is located in an anterior position and that the articular disc is not a determinant factor on condylar reorganization.

Cirurgia ortognática associada á cirurgia das ATMs acometidas por artrite reumatóide ou osteocondroma

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)