Since titanium-fixed prosthodontics fabricated by CAD/CAM systems have a relatively smooth surface, should be modified the adhesive surface of the machined crown to provide excellent bonding. The purpose of this study is to investigate the treatment condition of tribo-chemical treatment with silica-coated alumina particles to commercially pure titanium (cpTi) for the bonding characteristics with resin-based luting cements.
We used three kinds of alumina particles. Two types of silica-coated alumina powder with average particle sizes of 110, μm (TCP) and 30μm (TCS) were used for the tribo-chemical treatment. Alumina powder with an average particle size of 110μm (SB) was used for sandblasting as a control.
Both SiO₂ and Al₂O₃ were detected on cpTi plates after tribo-chemical treatment with TCP and TCS. Even if the surface modification of cpTi was affected by the pressure condition of the treatment, we suggested that cpTi should be subjected to tribo-chemical treatment at a pressure lower than 0.28 MPa, as recommended by the manufacturer, to decrease deformation and minimize volume loss.
The shear bond strength of cpTi after tribo-chemical treatment with a resin-based luting cement seemed to be high enough even when using a lower pressure and lower angles than those recommended by the manufacturer.
These findings suggest that tribo-chemical treatment can be applied for the practical surface treatment of cpTi to improve bonding with resin-based luting cements.

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In our previous study Fuji II LC EM (FLC), which is a resin-modified glass-ionomer cement, with a G-Bond (GB) and a UniFil^® Bond Self-Etching Primer (UP) showed higher and stabler shear bond strengths to dentin compared with a Cavity Conditioner (CC) attached to FLC. The objective of this study was to evaluate the effectiveness of these surface conditioners on FLC bonding strength to enamel.
FLC and Vitremer^TMR (VTM) were used as resin-modified glass-ionomer cements. CC, Self Conditioner (SC), UP, GB, Etching Liquid (EE) and Vitrmer^TM Primer (VP) for FLC and VP for VTM were used as surface conditioners. The bond strength of FLC with no conditioner (NC) was also tested. Flat enamel surfaces were prepared by grinding the proximal surfaces of 80 extracted human molars. The surface conditioners were handled according to the manufacturer's instructions. The shear bond strength was determined after storage in water at 37°C for 24 h.
The bond strengths of FLC (mean±SD; MPa) to enamel were 14.7±2.0 in CC, 12.8 ±1.1 in SC, 11.6±1.7 in UP, 17.0±1.6 in GB, 13.8 ± 1.4 in EE, 1.3 ± 1.1 in NC and 0.6 ± 1.1 in VP. That of VTM was 7.9 ± 1.6. Only GB showed significantly higher bond strength compared with CC. EE showed no difference and SC, UP, VP and NC showed significantly lower bond strength compared with CC.
CC is suitable in the cases of an enamel cavity or a shallow cavity as a surface conditioner of FLC. However, in a deep cavity or in a dentin cavity, GB or UP, which showed high and stable bond strength to dentin, are more suitable

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The aim of this study was to evaluate the recovery process of masticatory muscle activity after orthognathic surgery. The subjects were 5 adult female patients with mandibular prognathism who had received orthodontic treatment at the Department of Orthodontics of Showa University Dental Hospital before undergoing mandibular osteotomy at the Department of Oral Surgery of Showa University Dental Hospital. Surface electromyography was performed just prior to surgery, and 1 month, 3 months and 6 months postoperatively. Bilateral recordings were made from the masseter muscles and from the anterior and posterior temporal muscles during maximal clenching. The results were as follows : (1) One month postoperatively, all of the muscles showed markedly lower levels of activity than before surgery. However, the 3 month and 6 month examinations showed a tendency for gradual recovery of muscle function. (2) Six months after surgery, the degree of recovery varied, with the muscle function in some patients not recovering to preoperative levels. (3) Two of the patients showed distinct asymmetries of muscle activity in the preoperative recordings. In these cases, the asymmetries persisted 6 months after surgery. Our findings indicate that the recovery of muscle function in patients with mandibular prognathism who have undergone sagittal split ramus osteotomy varies between patients, and is likely to continue for longer than 6 months in most cases

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[in Japanese]

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