The effect of light-emitting diode and laser on mandibular growth in rats.

OBJECTIVE: To evaluate the effect of a light-emitting diode (LED) and/or low-level laser (LLL) with or without the use of anterior bite jumping appliances (also known as functional appliances [FAs]) on mandibular growth in rats. MATERIALS AND METHODS: Thirty-six 8-week-old male Sprague-Dawley rats weighing 200 g were obtained from Charles River Canada (St. Constant, QC, Canada) and were divided into six groups of six animals each. Groups were as follows: group 1: LLL; group 2: LLL + FA; group 3: LED; group 4: LED + FA; group 5: FA; and group 6: control (no treatment). Mandibular growth was evaluated by histomorphometric and micro computed tomographic (microCT) analyses. RESULTS: The LED and LED + FA groups showed an increase in all condylar tissue parameters compared with other groups. CONCLUSION: The LED-treated groups showed more mandibular growth stimulation compared with the laser groups.

Dose-dependent effects of genistein on bone homeostasis in rats' mandibular subchondral bone.

AIM: To investigate the effect of genistein on bone homeostasis in mandibular subchondral bone of rats. METHODS: Female SD rats were administered with genistein (10 and 50 mg/kg) or placebo by oral gavage for 6 weeks. Then the animals were sacrificed, and histomorphology and micro-structure of mandibular condyle were examined using HE staining and micro-CT analysis, respectively. The expression levels of alkaline phosphatase (ALP), osteocalcin (OC), osteoprotegerin (OPG), the receptor activator of nuclear factor κB ligand (RANKL) and estrogen receptors (ERs) in mandibular condyle were detected using real-time PCR. Cultured osteoblasts were prepared from rat mandibular condyle for in in vitro study. The cells were treated with genistein (10(-7) or 10(-4) mol/L) for 48 h. The expression of the bone homeostasis-associated factors and estrogen receptors (ERs) was detected using real-time PCR, and ER silencing was performed. RESULTS: At both the low- and high-doses, genistein significantly increased the bone mineral density (BMD) and bone volume, and resulted in thicker subchondral trabecular bone in vivo. In both in vivo and in vitro study, the low-dose genistein significantly increased the expression of ALP, OC and OPG, but decreased the expression of RANKL and the RANKL/OPG ratio. The high-dose genistein decreased the expression of all these bone homeostasis-associated factors. Both the low and high doses of genistein significantly increased the expression of ERß, while ERα expression was increased by the low dose genistein and decreased by the high dose genistein. ERß silencing abrogated most of the effects of genistein treatment. CONCLUSION: In rat mandibular condylar subchondral bone, low-dose genistein increases bone formation and inhibit bone resorption, while excess genistein inhibits both bone formation and resorption. The effects of genistein were predominantly mediated through ERß.

Neuromuscular diagnosis in orthodontics: effects of TENS on the sagittal maxillo-mandibular relationship.

AIM: This study was conducted in order to assess the changes in the occlusal position of the mandible after ULF (Ultra Low Frequency)-TENS relaxing procedure in subjects in pubertal growth phase with diagnosed Angle Class II division 1 and mandibular dentoalveolar retrusion. MATERIALS AND METHODS: This study was performed on 19 patients (13 females, 6 males) with an Angle Class II division 1, aged between 10 and 15 years old (mean age 12.26, SD 1.32), characterised by mandible dentoalveolar retrusion and optimal vertical facial dimension, diagnosed by clinical and cephalometric evaluation. Diagnostic neuromuscular registrations were made for all subjects. The casts were mounted on articulator in habitual intercuspal position with a tooth-guided wax bite registration. Reference points were chosen at molar level. Subsequently the same casts were mounted in myocentric position and compared to the habitual intercuspal position, assessing the sagittal shift after TENS procedure. STATISTICS: Mean and standard deviation were calculated on the amount of shifting at the left molar reference point after TENS procedure. Analysis of variance (ANOVA), using STATA statistics package, was carried out in order to evaluate the influence of sex and age on the amount of molar shift. RESULTS: Nine subjects showed, in the sagittal plane, a forward mandibular shift in neuromuscular myocentric position compared to habitual intercuspal position. Six subjects showed no differences between habitual and myocentric position in the sagittal plane. Four individuals showed a backward mandible shift after TENS indicating worsening of the II molar class in the sagittal plane. CONCLUSION: This study suggests that TENS recorded occlusion in subjects with Class II division 1 with mandible dentoalveolar retrusion allows to visualise an unusual trend of growth. The advancements of the mandible were not taken into account. These results could offer new diagnosis and prognosis methods for Class II malocclusions.

Fracturas del cóndilo mandibular: tratamiento funcional / Mandibular condyle fractures: functional management

Se realizó el estudio retrospectivo de la incidencia de las fracturas del cóndilo mandibular en los traumatismos faciales, ya sean únicas o asociadas a otras fracturas de la cara. La importancia en el diagnóstico y tratamiento fue centralizado en el análisis, resolución y seguimiento de 100 casos atendidos en los últimos 5 años...Sobre 100 traumatizados se instituyó un tratamiento funcional dividido en 4 etapas..Los resultados obtenidos tuvieron como objetivo fundamental, la recuperación funcional de la articulación témporomaxilodentaria, centrada en la reprogramación del aparato masticatorio y sus receptores. Hacemos referncia a la rehabilitación y mantenimiento de la función pterigoidea, la cual es la llave central de la reposición mandibular para recuperar la función masticatoria y la simetría de la boca y la cara

Fracturas del cóndilo mandibular: tratamiento funcional / Mandibular condyle fractures: functional management

Se realizó el estudio retrospectivo de la incidencia de las fracturas del cóndilo mandibular en los traumatismos faciales, ya sean únicas o asociadas a otras fracturas de la cara. La importancia en el diagnóstico y tratamiento fue centralizado en el análisis, resolución y seguimiento de 100 casos atendidos en los últimos 5 años...Sobre 100 traumatizados se instituyó un tratamiento funcional dividido en 4 etapas..Los resultados obtenidos tuvieron como objetivo fundamental, la recuperación funcional de la articulación témporomaxilodentaria, centrada en la reprogramación del aparato masticatorio y sus receptores. Hacemos referncia a la rehabilitación y mantenimiento de la función pterigoidea, la cual es la llave central de la reposición mandibular para recuperar la función masticatoria y la simetría de la boca y la cara

Achados radiográficos, sinais e sintomas nas disfunçöes da articulaçäo temporomandibular / Radiographic findings, signs and symptoms in temporomandibular joint dysfunctions

Os achados radiográficos e os sinais e sintomas de pacientes com disfunçöes da articulaçäo temporomandibular (ATM) foram estudados. Através da incidência transcranial para ATM, foram verificadas a presença de alteraçöes degenerativas e a estimativa de excursäo condilar. Pelo exame clínico, foram avaliados dados como queixa principal, padräo de ocorrência de dor, sinais de dor muscular e sinais articulares de disfunçäo. As alteraçöes radiográficas mais freqüentes foram as degenerativas. As alteraçöes degenerativas mais freqüentes foram, em ordem decrescente, facetamento, eburnaçäo e osteofito. As alteraçöes degenerativas foram mais freqüentes no côndilo do que na eminência articular. A estimativa de excursäo condilar foi, em ordem decrescente, normo, hiper e hipoexcursäo. Näo foi observada relaçäo entre achados radiográficos e sinais ou sintomas específicos

A macroscopic study of the effect of oxygen on the growth of the rat mandible and femur in vivo.

The effect of oxygen on the growth of the mandible was studied in 40 Long-Evans/Turku rats. Pregnant rats were exposed to increased oxygen tension for 16 days from 7 to 23 days of gestation. After parturition the young rats were kept under normal laboratory conditions until the age of 50 days and then killed for macroscopic examination. Fifteen rats were exposed to increased oxygen tension from 15 to 50 days postnatally and then killed. The control animals were kept under normal laboratory conditions throughout. A prenatal increase in oxygen tension had no marked effects on the dimensions of the mandible at the age of 50 days, although the height of the mandible was increased when the dimensions were corrected for body weight. A postnatal increase in oxygen tension reduced the length of the mandible but increased its height. Although low oxygen tension has been thought to favor cartilage formation, and although function is considered necessary for the growth of the mandibular condyle, it seems that the latter process is stimulated by increased oxygen tension and reduced by loading.

Relationships between mandibular joint size and craniofacial size in human groups.

Substantial evidence attests to the capability of the joint to undergo morphological alteration in response to biomechanical forces transmitted to it during function. Measurements expressing the size of mandibular condyles and fossae were obtained from skulls representative of a broad spectrum of subsistence practices and tooth use. Craniofacial dimensions were measured for some groups. Considerable differences in joint size were noted between groups roughly consistent with known or presumed intensity of masticatory stress. Size was largest in the hunter-gatherers, intermediate in aboriginal horticulturalists and smallest in 20th century American caucasoids and 17th century British. In each group, male joint size was absolutely larger than females. With the exception of condylar breadth, male joint dimensions were not relatively larger than female when corrected for differences in craniofacial size. In contrast, same-sex comparisons of Eskimo and American caucasoid means adjusted for differences in craniofacial size showed joint size in Eskimos to be significantly larger, both absolutely and relatively. Eskimo females had relatively larger joints than American caucasoid males. Thus, intergroup differences in joint size persist even when differences in craniofacial size are taken into account. Although the influence of genetic factors cannot be excluded, differences in the nature or intensity of tooth use during growth may account, at least in part, for the observed differences in joint size.

Tooth attrition and the temporomandibular joint.

1. It is thought the differences shown to exist between the unworn sample and the worn sample would have been clearer if the criteria for the classification of worn had been more severe. Examination of the ranges of measurements would make one suspect some subjects suffered dental attrition to a degree that no enamel was left on the occlusal surfaces of the third molars without showing damage elsewhere. The author did not feel competent to assess third molars that had not only lost all their occlusal enamel but also one mm of dentin, so was unable to make his worn classification more stringent. Again the reader is reminded that broeken down or "worn out" dentitions were specifically excluded from the samples...