Evaluation of Tissue Tensions in Segmental Maxillary Osteotomies by Finite Element Analysis.

PURPOSE: Maxillary segmentation associated with Le Fort I osteotomy is a surgical technique used to correct transverse maxillary discrepancies. Notwithstanding advances over the years, there are still complications arising from this surgical intervention, including the maintenance of sufficient blood supply and excessive tension of the palatal fibromucosa. Therefore, the aim of this study was to analyze the effect of the force applied during surgery on bone dislocation and fibromucosa tension in different maxillary segmentation designs by finite element analysis. METHODS: A 3-dimensional skull was generated from tomographic images. We worked with 4 models. In 2 models, we divided the maxilla into 3 segments: one with osteotomy between the lateral incisor and canine and the other between the canine and first premolar. In the other 2 models, we divided the maxilla into 4 segments with the same osteotomies previously mentioned. A force of 100 N was applied to the palatal surfaces of the right and left permanent maxillary first molars. RESULTS: When comparing the technique between 3 and 4 segments with the same interdental osteotomy, we evidenced greater bone dislocation and less fibromucosa tension in the 3-segment technique. When we contrast the same number of segments with different regions of interdental osteotomy, we noticed a lower fibromucosa tension and a greater bone dislocation in the lateral incisors and canine. CONCLUSIONS: The technique with 3 segments and with interdental osteotomy between the lateral incisor and canine presented less resistance, allowing greater dislocation and consequently generating less mucosa tension.

Immunohistochemical panel of degenerated articular discs from patients with temporomandibular joint osteoarthritis.

BACKGROUND: Temporomandibular joint osteoarthritis (TMJOA) is a progressive degenerative disease caused by imbalance between anabolic and catabolic stimuli. OBJECTIVE: The aim of this study was to evaluate histopathological changes, collagen degeneration and the expression of eleven TMJOA biomarkers in articular discs. METHODS: Specimens were obtained from eight female patients submitted to discectomy. Discs were divided into anterior band (AB), intermediate zone (IZ) and posterior band (PB) for computerised histomorphometric analyses. Each was assigned a histopathological degeneration score (HDS). Collagen degeneration was assessed with Picrosirius-polarisation method. Biomarkers were evaluated through immunohistochemistry, including IGF-1, OPG, VEGF, TNF-α, FGF-23, IHH, MMP-3, MMP-9, TGF-ß1 , BMP-2 and WNT-3. Image processing software was used to calculate average immature collagen ratios and immunostained areas. Spearman rank tests were applied to verify correlations, with significance level of 0.05. RESULTS: The HDS showed negative correlation with expression of VEGF in IZ and PB (P < .05) and positive with TNF-α in AB (P < .01). Collagen degeneration correlated with TGF-ß1 (P < .05), BMP-2 (P < .01) and IHH (P < .05) immunostained areas in the IZ; TGF-ß1, BMP-2 and IHH expression correlated among each other in AB and IZ (P < .05). CONCLUSION: Angiogenesis and tissue fragmentation may result from aberrant physiologic responses mediated by VEGF and TNF-α, compromising TMJ discs during OA progression. The expression of TGF-ß1, BMP-2 and IHH could be related to collagen degeneration in displaced discs and may participate in TMJOA pathogenesis.