Bonding of dental restorative materials to tooth structure can be adversely affected by numerous clinical factors. Bonding agents and self-adhesive materials that are affected by these factors are often considered to be technique-sensitive materials. Factors that can affect in vitro bond strength to human teeth include substrate (enamel, superficial dentin, deep dentin; permanent versus primary teeth; caries-affected dentin), phosphoric acid when used in conjunction with acidic primers or self-etching adhesives, preparation by air abrasion and laser, moisture, contaminants (saliva, blood, eugenol, peroxides), desensitizing agents, astringents, and even self-cured restorative materials. This paper reviews the literature with a focus on studies conducted at the Houston Biomaterials Research Center from 1993-2004. Results show that in vitro bond strengths can be reduced by more than 50 percent when bonding conditions are not ideal. Thus the clinician must be aware of clinical factors that affect bonding and must have techniques to counteract these factors. A dental manufacturer seeking to improve a bonding system should strive to decrease the technique sensitivity of the system.

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In the medical polymer material development, our company aims at the worldwide marketing as an enterprise with the advanced expertise. Absorbable surgical suture and monofilaments surgical suture material and absorbable bones fixation devices, etc. offer the raw material to each manufacturer as a raw material supplier. And, surgical adhesives and denture bases, etc. are produced in our company, and it is offered to the direct user.

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Biomimetic nano-apatite collagen composite is a promising biomaterial for bone tissue engineering. However, the low mechanical property and poor shaping property limited its application. We had prepared a three-dimensional scaffold material using a mineralized collagen and a degradable polymer, named as nHAC/PLA, which satisfied both the high biocompatibility and enough mechanical properties. The co-culture experimental results with human neutrophils demonstrate that this biomaterial has almost no initial inflammations. The osteoblasts were separated from the neonatal rat calvaria. By the static cell culture, we developed the three-dimensional osteoblasts/composite bone-like construct in vitro. It was shown by CLSM and OM observation that the cells could spread and proliferate throughout the inner-pores of the scaffold material.

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Immobilization of antimicrobial peptide "Histatin-5" on PMMA is considered to be useful to create the antibacterial denture base. QCM-D measurements revealed that surface modifications with oxgen and nitrogen - plasma treatment enhanced adsorption of Histatin-5 onto PMMA.

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In this study the fracture mode was defined for both conventional tests and micro-tensile bond test, and then the relationship between bond strength and fracture mode was theoretically clarified based on the results. Considering an influence of specimen dimension to bond strength, fracture mode was discussed using new concept of adhesion theory.

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Human flat dentin surface ground with SiC paper (#180, 600 or 2000) was treated with one of 4 all-in-one adhesive systems (AP Plus, i Bond, G-Bond, Xeno CF Bond_II_). The bonding interface was ultrastructurally observed in TEM to clarify the effect of smeared layer on the bonding performance of all-in-one adhesive susyems.

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The study was aimed to investigate the effect of grinding status of dentin on all-in-one adhesive/dentin bonding. Human flat dentin surface ground with SiC paper (#180, 600 or 2000) was treated with 2 all-in-one adhesive systems (i Bond or G-Bond). Microtensile bond strength was measured after 24 hour. Additionally, etching effects on the gourd dentin surface were observed in SEM.

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In order to know the property of diversity of p-HAp, the experiments were observed on dynamics of Streptococcus mutans, oral complements and IgA antibody.

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Concentrated fluoric, nitric, hydrochrolic, sulfuric, and phosphoric acids were used for surface modification of titanium. After the etching, the surface was characterizaed. XRD indicated the formation of hydrogen titanium. Etching in sulfuric acid was the most attractive.

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Using strength of materials combined with computer programming technique, influence of variation of biting force as to internal and external forces produced by masticatory muscle forces, temporomandibular joint reaction forces and biting forces with teeth was analyzed. According to an increase of biting forces, shearing force, bending moment and torsion moment increased in a positive linear form. The method presented in this study is useful for analysis of influence of biting force with respect to internal and external forces of a human mandible by strength of materials.

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The teeth replica for auto-implantation was made by opt-modeling system with three-dimensional X-ray micro-focus CT. The cavity of the auto-implantation was prepared by the tooth replica, then the wisdom tooth was set and fixed for several months. After implantation, the three-dimensional X-ray CT were taken. Mechanical/physical properties were simulated and evaluated by three-dimensional finite element analysis.

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In the previous study we have reported on the application of VR haptic device in dental implantology, and CAD/CAM fabrication of bone stent. In the present study the bone stent and bone model were fabricated by FDM(Fused Deposition Modeling). Adaptability of the stent on the bone was examined before operation, and drilling on the bone in the implant surgery was done using the bone stent.

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Dental metallic materials used in oral environment are required to have high corrosion resistance because they contact to various solution such as saliva, mouth-wash, and so on. In this study, we examine electrochemical corrosion behavior of Au-Ag-Pd, gold alloy, Co-Cr alloy and titanium in various mouth-wash solutions, and we discussed the corrosion behavior on dental metallic materials in oral environment.

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Several injectable ceramics have been introduced in dental field. Recently, the effects of cyclic loading on ceramics fatigue properties have been recognized. However, the effects of cyclic loading on dental injectable ceramics have not been clearly confirmed. In the present study, three commercial injectable ceramics were examined to evaluate effects of cyclic loading on fatigue properties.

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