Toru Inomata

Patient-specific cutting guides are used for safe and accurate jaw resection during oral and maxillofacial surgery. This study investigated the effect of shavings from 3D-printed cutting guide materials during surgery on bone healing. The biocompatibility of commercially available biocompatible polymers including photopolymer resin (PP) and polyamide resin (PA) materials was assessed in the present study. The viability of mouse osteoblast-like MC3T3E-1 cells was evaluated upon coculture with the materials. Furthermore, the effects of PP and PA as additives on bone formation were investigated in a rat calvarial bone defect model. Both PP and PA were biocompatible and allowed cells to attach to them. However, both materials could be damaged when cutting devices were used, and their shavings impaired osteoblast proliferation and bone formation. Cutting guide materials are designed to be biocompatible when they are fabricated according to the manufacturer’s protocol. Nevertheless, the polymer shavings generated during jaw cutting might adversely affect bone healing.

Angiogenesis is an important issue related to normal growth and differentiation, and it is a critical issue in the progression of human disease in oral mucosa. Tooth marks occur after clenching the teeth for a long period under muscle tension in the human oral cavity. However, the sites of angiogenesis, cell differentiation and microvessel density are not known for human mucosa with tooth marks. Therefore, we investigated the relationship between the markers of differentiation (Ki-67), angiogenesis (CD31, D2-40, VEGF-A), and marks from teeth in the second molar region using immunohistochemical methods. In addition, we compared these areas with the mucous membrane. Our results revealed blood and lymphoid vessels in irregular mucosa structures, and the vessels in the oral mucosa were observed in three types of samples: dentulous, denture attachment (containing partial teeth), and edentulous samples. The localization of the angiogenesis was related to the structure of the oral mucosa of connective tissue in humans, such as the mucosal fold-like of the buccal region. Using principal component analysis (PCA), we found that tooth occlusal condition, gender, anti-VEGF-A reaction levels in oral mucosa of the epithelium were positive factors in all groups, which is in contrast to the negative association of Ki-67 reaction in the epithelium and CD31 expression. In addition, Ki-67 reaction in oral mucosa had negative impacts, in contrast to the positive association of D2-40. These PCA properties provide useful information for future study of tumour progression or mechanical stress in remodelling of oral mucosa and angiogenesis. Moreover, mechanical stress of the occlusal condition may be correlated with tumour angiogenic activity and cell differentiation in human oral mucosa.