Photobiomodulation and Mandibular Advancement Modulates Cartilage Thickness and Matrix Deposition in the Mandibular Condyle.

Objective: We evaluated the effects of photobiomodulation (PBM), mandibular advancement (MA), and the combination of both treatments (PBM+MA) on condylar growth, by the analysis of cartilage and bone formation, fibrillar collagen deposition, proteoglycan content, cell proliferation, and clastic cell index (CCI). Methods: Forty male Wistar rats were randomly assigned to CONTROL, PBM, positive control-MA, and PBM+MA groups. The appliance was worn 10 h/day. Laser was irradiated bilaterally on mandibular condyles in 8 alternate days (1 irradiation point per condyle) using the following parameters: 780 nm, 10 J/cm2, 40 mW, 1 W/cm2, 10 sec/point, 0.4 J/point, and cumulative dose per point: 3.2 J. PBM+MA received both treatments simultaneously. After 15 days, the animals were euthanized and the condyles dissected and embedded in paraffin. Histological sections from the intermediate portion of the condyle were used for morphometric analysis. The relative frequency (%) of fibrillar collagens was determined in sections stained with picrosirius red-hematoxylin under polarized light or Gömöri's method for reticular fibers. Proteoglycan content was evaluated by computerized photocolorimetric analysis. CCI was determined by tartrate-resistant acid phosphatase (TRAP), and proliferating cell nuclear antigen (PCNA) was detected by immunohistochemistry. Results: PBM and MA influenced condylar cartilage thickeness and matrix deposition, but none of the treatments affected significantly the area of the condyle. CCI were not influenced by the treatments, but clastic cells distribution was influenced by MA and PBM+MA treatments. There was no significant difference in proliferating cells among the groups. Conclusions: This study demonstrated that PBM and MA stimulates matrix deposition and cartilage thickening in the mandibular condyle, but was not able to demonstrate a synergistic effect between the treatments. Additional studies should be conducted to evaluate the possible synergistic effect between PBM and MA.

Nutritional supplementation with myo-inositol in growing mice specifically augments mandibular endochondral growth.

INTRODUCTION: The purpose of this study was to examine growth-promoting effects of myo-inositol nutritional supplementation on the mandible in experimental animals. METHODS: Mice were fed on diets that contained various concentration of myo-inositol for 3 to 12 weeks. The length of the mandible, maxilla, and femur were measured on µCT images. The mandible and tibia were examined histologically and immunohistochemically. The effects of myo-inositol on cell proliferation and chondrocytic differentiation were examined using ATDC5 cells. RESULTS: Myo-inositol supplementation had no effects on body weight, length, and maxilla and femur lengths. However, the length of mandible and the thickness of the mandibular condylar cartilage (MCC) were increased by myo-inositol supplement. Microarray analysis revealed that Pik3cd was highly expressed in MCC as compared to that in the cartilage of the tibial growth plate, which was confirmed by real-time RT-PCR and immunohistochemistry. ATDC5 cells also highly expressed Pik3CD. Myoinositol induced increases in cell proliferation and chondrocytic differentiation in ATDC5 cells. The addition of a PIK3CD inhibitor blocked the induction of cell proliferation by myo-inositol in ATDC5 cells. CONCLUSIONS: Nutritional supplementation with myo-inositol in growing mice augmented mandibular endochondral growth without any systemic effects. The specific promotion of mandibular growth by myoinositol is primarily dependent on the specific intensive expression of PIK3CD in the MCC.

La artritis reumatoidea juvenil y su influencia en la alteración de desarrollo de la mandíbula / Juvenile rheumatoid arthritis and its influence on the alteration of jaw development

La artritis reumatoidea juvenil (ARJ) es una enfermedad inflamatoria autoinmune que se presenta en niños menores de 16 años. Es de curso crónico, etiología desconocida, y afecta sobre todo las articulaciones, como la temporomandibular (ATM). El daño de la ATM puede ocasionar: alteraciones en el crecimiento facial (micrognatia), maloclusión clase II, mordida abierta anterior, desviaciones laterales, erosiones óseas, destrucción del cón-dilo, oclusión disfuncional y alteración de la estética facial, entre otras consecuencias. La posición oclusal neurofisiológica lograda por medio de elementos electrónicos, como el Transcutaneus Electrical Neural Stimulation (TENS), y mantenida por el Dispositivo Intaroral (DIO) podría posibilitar la remodelación de la cabeza del cóndilo, en pacientes en crecimiento, en los que la enfermedad se halla controlada, regulando así también la sintomatología dolorosa...

The effects of low-level laser therapy on condylar growth with a mandibular advancement appliance in rats.

OBJECTIVE: The aim of this study was to evaluate the effects of low-level laser therapy (LLLT) on condylar growth with a mandibular advancement appliance in rats. BACKGROUND DATA: Researchers studied new methods such as laser, for mandibular condyle growth stimulation and acceleration with or without functional appliances in experimental animals, but the specific mechanism and laser energy density values for condylar biostimulation and bone cell activities are still unknown. METHODS: Forty-eight 8-week-old male Wistar albino rats weighing between 260 and 280 g were randomly divided into four groups. Group I was the control group; group II was the mandibular advancement appliance group; group III was the 8 J/cm(2) (0.25 W, 20 sec) laser irradiation with mandibular advancement appliance group; and group IV was the 10 J/cm(2) (0.25 W, 25 sec) laser irradiation with mandibular advancement appliance group. Experimental rats in groups III and IV were stimulated with a low-level laser in the temporomandibular joint region bilaterally 15 times over 30 days. Morphological changes in the mandible were evaluated with lateral radiographs before and after the study with selected linear and angular measurements. Pearson correlation test, Friedman, Kruskal-Wallis, and Mann-Whitney U tests were used for statistical analysis. RESULTS: According the lateral radiograph results, the growth of mandibles in the experimental groups was significantly more than that of the control group (p<0.05). Group III also showed greater mandibular growth than the other groups (p<0.05). CONCLUSIONS: We concluded that an intraoral appliance with LLLT, including chosen parameters, can stimulate condylar growth and increase mandibular advancement.

Impact of local steroid or statin treatment of experimental temporomandibular joint arthritis on bone growth in young rats.

INTRODUCTION: Juvenile idiopathic arthritis in temporomandibular joints (TMJs) is often treated with intra-articular steroid injections, which can inhibit condylar growth. The purpose of this study was to compare simvastatin (a cholesterol-lowering drug that reduces TMJ inflammation) with the steroid triamcinolone hexacetonide in experimental TMJ arthritis. METHODS: Joint inflammation was induced by injecting complete Freund's adjuvant (CFA) into the TMJs of 40 growing Sprague Dawley rats; 4 other rats were left untreated. In the same intra-articular injection, one of the following was applied: (1) 0.5 mg of simvastatin in ethanol carrier, (2) ethanol carrier alone, (3) 0.15 mg of triamcinolone hexacetonide, (4) 0.5 mg of simvastatin and 0.15 mg of triamcinolone hexacetonide, or (5) nothing additional to the CFA. The animals were killed 28 days later, and their mandibles were evaluated morphometrically and with microcomputed tomography. RESULTS: The analysis showed that the TMJs subjected to CFA alone had decreased ramus height compared with those with no treatment (P <0.05). Groups that had injections containing the steroid overall had decreases in weight, ramus height, and bone surface density when compared with the CFA-alone group (P <0.0001). Groups that had injections containing simvastatin, however, had overall increases in weight (P <0.0001), ramus height (P <0.0001), condylar width (P <0.05), condylar bone surface density (P <0.05), and bone volume (P <0.0001) compared with the groups receiving the steroid injections, and they were not different from the healthy (no treatment) group. CONCLUSIONS: Treatment of experimentally induced arthritis in TMJs with intra-articular simvastatin preserved normal condylar bone growth.

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.

The effect of low level laser on condylar growth during mandibular advancement in rabbits.

INTRODUCTION: It has been shown that Low Level Laser (LLL) has a positive effect on bone formation. The aim of this study was to evaluate the effect of low level laser on condylar growth during mandibular advancement in rabbits. MATERIALS AND METHODS: Continuous forward mandibular advancement was performed in fourteen male Albino rabbits with the mean age of 8 weeks and the mean weight of 1.5 ± 0.5 kg, with acrylic inclined planes. The rabbits were randomly assigned into two groups after 4 weeks. LLL (KLO3: wave length 630 nm) was irradiated at 3 points around the TMJ, through the skin in the first group. The exposure was performed for 3 minutes at each point (a total of 9 minutes) once a day for 3 weeks. The control group was not exposed to any irradiation. The rabbits in both groups were sacrificed after two months and the histological evaluation of TMJ was performed to compare fibrous tissue, cartilage, and new bone formation in condylar region in both groups. Disc displacement was also detected in both groups. Student's t-test, Exact Fisher and Chi square tests were used for the statistical analysis. RESULTS: The formation of fibrous tissue was significantly lower, while bone formation was significantly greater in lased group as compared with control group. The thickness of cartilage did not differ significantly between two groups. CONCLUSION: Irradiation of LLL (KLO3) during mandibular advancement in rabbits, increases bone formation in condylar region, while neither increase in the cartilage thickness nor fibrous tissues was observed.

Association between condylar morphology and changes in bony microstructure and sub-synovial inflammation in experimental temporomandibular joint arthritis.

BACKGROUND: In juvenile idiopathic arthritis involvement of the temporomandibular joints (TMJs) is often associated with mandibular growth deviations. The relation between the growth deviations and severity of the inflammation, condylar shape, the micro-architecture, and the quality of the bone has not previously been investigated. This paper studies the effect on the bony structures in mandibular condylar development in rabbits with antigen-induced arthritis. METHODS: Included were 42 juvenile rabbits with ovalbumin-induced arthritis of the TMJs treated with intraarticular saline, intraarticular etanercept or subcutaneous etanercept. A TMJ from each animal was scanned using micro-computed tomography and structural parameters were calculated. Three-dimensional reconstructions of the mandibular condyle were scored blindly as normal or abnormal. TMJs were stratified for condylar morphology and were evaluated against data on trabecular structural parameters, inflammation, degree of mineralization, overall mandibular growth, and mineral apposition rate. RESULTS: Abnormal morphology were seen in 15/32 animals available for data analysis. Erosions were an uncommon finding. Abnormal morphology was strongly related to the degree of inflammation. The trabecular separation was larger in group with abnormal morphology than in the group with normal morphology. Abnormal condylar morphology was not associated with overall mandibular growth. No differences were observed in mineral apposition rate. No differences in structural parameters were seen according to treatment modality. CONCLUSION: We showed that severe inflammation in the TMJs during mandibular development was associated with morphological changes in the mandibular condyle. These changes were predominantly seen at the macro-morphological level and only very few differences were structural.

The effect of 904 nm low level laser on condylar growth in rats.

A growth center of the mandible that contributes to its length and height is the mandibular condyle. Proliferation of prechondroblasts, followed by synthesis of the extracellular matrix and hypertrophy of the cartilage cells, governs the major part of condylar growth. The sample consisted of 54 male rats, weighing between 60 g and 80 g, divided randomly into three groups. Group I was the control group, group II was irradiated bilaterally, and group III was irradiated on the right side. Laser irradiation (lambda = 904 nm, 2000 Hz, pulse length 200 ns and output power 4 mW) was performed, and the procedure was repeated after a 50-day interval. Two months later, the rats were killed. In a single blind manner the lengths of denuded mandibles and the lengths of mandibles on soft tissue were measured. The growth of the mandibles in the unilaterally irradiated group (P < 0.001) and the bilaterally irradiated group (P < 0.05) was significantly more than that in the control group. There was no significant difference between right and left condylar growth in the bilaterally irradiated group (P = 0.3). Soft tissue analysis also verified these results (P < 0.001). Histomorphometric results also revealed a significant difference between laser-irradiated groups and the control group (P < 0.01). We concluded that particular laser irradiation with the chosen parameters can stimulate condylar growth and subsequently cause mandibular advancement. These findings might be clinically relevant, indicating that low level laser irradiation can be used for further improvement of mandibular retrognathism.

Low-intensity pulsed ultrasound stimulation of condylar growth in rats.

OBJECTIVE: To test the hypothesis that low-intensity pulsed ultrasound (LIPUS) stimulation does not histologically affect the growth of mandibular condylar cartilage. MATERIALS AND METHODS: Thirty-five 20-day-old Sprague-Dawley rats were assigned to experimental and control groups. Experimental rats were stimulated with LIPUS in the temporomandibular joint (TMJ) region unilaterally, for 10 or 20 minutes for 20 days. After euthanasia, histological specimens were analyzed qualitatively and histomorphometrically at the anterior and posterior aspects of the mandibular condyle, including the condylar cartilage and the area and perimeter of subchondral bony trabeculae. RESULTS: LIPUS stimulation may alter the histological arrangement of the condylar bone and cartilage, showing qualitative differences on specimens treated for 10 or 20 minutes daily compared with controls. Cartilaginous layer thickness was not affected by LIPUS stimulation to a significant level, but was modified at the relative layer thickness within the cartilage at the anterior aspect of the condyle (P < .05). At the subchondral bone level, 20-minute stimulation significantly increases trabecular perimeter (P = .01). CONCLUSIONS: LIPUS application may affect mandibular growth pattern in rats acting at the cartilage and bone level. The effect of LIPUS on the growing condyle is expressed through a variation in trabecular shape and perimeter. A greater response is achieved when stimulated for 20 minutes instead of 10 minutes daily.

Adult stem cell driven genesis of human-shaped articular condyle.

Uniform design of synovial articulations across mammalian species is challenged by their common susceptibility to joint degeneration. The present study was designed to investigate the possibility of creating human-shaped articular condyles by rat bone marrow-derived mesenchymal stem cells (MSCs) encapsulated in a biocompatible poly(ethylene glycol)-based hydrogel. Rat MSCs were harvested, expanded in culture, and treated with either chondrogenic or osteogenic supplements. Rat MSC-derived chondrogenic and osteogenic cells were loaded in hydrogel suspensions in two stratified and yet integrated hydrogel layers that were sequentially photopolymerized in a human condylar mold. Harvested articular condyles from 4-week in vivo implantation demonstrated stratified layers of chondrogenesis and osteogenesis. Parallel in vitro experiments using goat and rat MSCs corroborated in vivo data by demonstrating the expression of chondrogenic and osteogenic markers by biochemical and mRNA analyses. Ex vivo incubated goat MSC-derived chondral constructs contained cartilage-related glycosaminoglycans and collagen. By contrast, goat MSC-derived osteogenic constructs expressed alkaline phosphatase and osteonectin genes, and showed escalating calcium content over time. Rat MSC-derived osteogenic constructs were stiffer than rat MSC-derived chondrogenic constructs upon nanoindentation with atomic force microscopy. These findings may serve as a primitive proof of concept for ultimate tissue-engineered replacement of degenerated articular condyles via a single population of adult mesenchymal stem cells.

Formation of a mandibular condyle in vitro by tissue engineering.

PURPOSE: Mandibular reconstructive procedures often produce significant donor site morbidity. Recently, the use of minimally invasive techniques has been reported for mandibular reconstruction with decreased morbidity at the primary operative site. To date, these techniques have not addressed the graft donor site. We hypothesize that tissue-engineering techniques may be used to fabricate bone and thereby eliminate donor site morbidity. METHODS: Porcine mesenchymal stem cells (pMSCs) were isolated from the bone marrow of 3 Yucatan minipigs and grown in standard culture flasks. When they became near-confluent, cells were detached and replated with the addition of osteogenic supplements. A model of a porcine mandibular condyle was made and used to fabricate porous polymer scaffolds from biodegradable poly DL-lactic-co-glycolic acid (PLGA). Differentiated osteoblasts were transferred to the PLGA scaffold and cultured for 6 weeks in a rotational oxygen-permeable bioreactor system. The cultured constructs, consisting of scaffold and cells, were evaluated by gross, radiologic, and histologic examinations. RESULTS: The engineered constructs were white and hard and had a shape that closely resembled that of the model condyle. Plain radiographs demonstrated that the radiodensity of the construct was between that of the normal condyle and that of control scaffolds. Histologically, bone was observed on the entire surface of the PLGA scaffolds with an average thickness of 0.03 mm. Bone was not observed in the control scaffolds. CONCLUSION: In this pilot study, autologous tissue-engineered bone constructs were successfully made by combining biodegradable polymers and pMSCs.

Effects and noneffects of personal environmental experimentation on postnatal craniofacial growth.

Genetic makeup, as well as various environmental factors, such as gravity, temperature, disease, trauma, inflammation, radiation, and chemicals, may affect skeletal growth sites and centers, thereby causing faulty growth of bone(s). The degree of the subsequent deformity will depend not only on the type, intensity, extent, and chronology of the noxious agent but also on the site and its particular susceptibility and growth activity. Over the years, I conceived, designed, initiated, and carried out a series of experiments in regard to bone(s), in both young and adult animals. Eventually, I directed my efforts principally toward local surgical experimentation as it related to both normal and abnormal gross postnatal craniofacial growth. Because of the wide variety of different structures, their interrelated individualities, and the challenges presented in both its richness of sites of growth and complexity, the skull proved to be a most unusual source of study. The purpose of this selective, organized, and limited review, analysis, and summary of personally conducted experiments is to relate certain aspects of growth with change and nonchange to age, sites, rates, factors, and mechanisms. In many instances, there are correlations between basic research findings and clinical practice. There is no such similar report in the literature. This retrospective study brings it all together.

Temporomandibular joint remodeling in adolescents and young adults during Herbst treatment: A prospective longitudinal magnetic resonance imaging and cephalometric radiographic investigation.

The aim of this prospective study was to analyze and compare the temporomandibular joint adaptive mechanisms in 25 adolescent and 14 young adult Class II malocclusions treated with the Herbst appliance. Temporomandibular joint remodeling was analyzed by magnetic resonance imaging. In each subject, 4 magnetic resonance images of both temporomandibular joints were available: before treatment, at the start of treatment (when the Herbst appliance was placed), during treatment (6 to 12 weeks after appliance placement), and after treatment (when the appliance was removed). Furthermore, effective temporomandibular joint changes (the sum of condylar remodeling, fossa remodeling, and condyle-fossa relationship changes) were analyzed with the aid of lateral cephalometric radiographs from before and after treatment. All subjects were treated to Class I or overcorrected Class I dental arch relationships, and their mandibles became significantly (P <.001) more prognathic. After 6 to 12 weeks of Herbst treatment, signs of condylar remodeling were seen at the posterosuperior border in 48 of the 50 adolescent condyles and in 26 of the 28 young adult condyles. Bilateral remodeling of the mandibular ramus could be detected in 1 adolescent and 2 young adult patients. Signs of glenoid fossa remodeling at the anterior surface of the postglenoid spine were noted in 36 adolescent and 22 young adult temporomandibular joints. Effective temporomandibular joint changes during treatment were more horizontally directed and larger in both adolescents and young adult patients treated with the Herbst appliance than in an untreated group of subjects with ideal occlusion (Bolton standards). The increase in mandibular prognathism accomplished by Herbst therapy in both adolescents and young adults seems, in particular, to be a result of condylar and glenoid fossa remodeling. Because the Herbst appliance is most successful in Class II patients also at the end of the growth period, the treatment method could be an alternative to orthognathic surgery in borderline skeletal Class II cases. Magnetic resonance imaging renders an excellent opportunity to visualize the temporomandibular joint remodeling growth processes.

Dimensional growth and extracellular matrix accumulation by neonatal rat mandibular condyles in long-term culture.

Mandibular condyles in organ culture commonly have been used as a model system for examination of the factors that influence skeletal growth and development. The work reported here complements previously published histological studies by providing quantitative temporal information on growth and matrix accumulation. Condyles maintained for as long as 5 weeks in serum-free and 1% serum-supplemented culture media were found to remain viable and metabolically active as demonstrated by continued dimensional growth as well as cell and matrix accumulation. Growth occurred by a combination of cell proliferation, matrix synthesis and accumulation, and cell hypertrophy (with the latter two mechanisms dominating). Increases in tissue volume correlated directly with increased glycosaminoglycan content; both increased 7-fold over 5 weeks. In comparison with serum-free culture, after 35 days in medium containing 1% serum, glycosaminoglycan content was 24% lower and collagen content was 36% higher, whereas dry weight, condyle length, and DNA content were not significantly different; in addition, histological observation suggested that, for samples cultured with serum, chondrogenic phenotype had been lost from some regions. The temporal behavior for all growth parameters exhibited a transient phase 1-2 weeks in duration followed by a steady-state period in which dimensions and tissue constituents or content increased at a constant or near constant rate. Comparison of the rates of incorporation of [35S]sulfate with glycosaminoglycan content in serum-free cultures suggests that the loss of glycosaminoglycan occurs only initially or is negligible; therefore, under these baseline conditions, cartilage glycosaminoglycan content reflects the biosynthetic rate. The high degree of reproducibility seen during steady-state growth suggests that these data provide reliable baseline information and further supports the notion that this model system is useful for investigation of the effects of specific physical factors on in vitro growth and development.

Growth of the skeletal units of the rat mandible in acute renal failure experimental model.

A study of the effect of acute renal failure (ARF) on the growth of the skeletal units of the mandible was performed. Male Wistar rats weighing 35-40 g were assigned to three groups. One of the groups received a basal choline-deficient diet ad libitum. A second group was pair-fed with the first one and was given a basal diet supplemented with 0.35 g choline chloride/100 g of diet. The third group was fed a basal diet plus 0.35 g choline chloride/100 g of diet ad libitum and used as the normal control. Body length, renal function parameters and measurements of the mandible were recorded at the end of a 12-day period on the different diets. Food intake and body weight were recorded every day. Plasma urea and creatinine concentrations markedly increased over the first 12 days of exposure to a choline-deficient diet. Significant increases in urine volume and significant depressions in urine osmolality were also observed. The average body weight and body length gains for rats given the choline-deficient diet were lower than those of control rats. There were no significant differences between the average body weight and body length of pair-fed and normal rats. All skeletal measurements of the mandible of the choline-deficient group differed significantly from those of the control group. These differences varied between 7% and 30%. The skeletal units of the mandible of the pair-fed group did not differ significantly from ad libitum controls. This study suggests that this rat model can be used for the investigation of the different alterations observed in uremia.(ABSTRACT TRUNCATED AT 250 WORDS)