Longitudinal study on risk indicators for peri-implantitis using survival-time analysis.

PURPOSE: The purpose of this study was to evaluate the incidence of peri-implantitis and to identify potential associated risk indicators. METHODS: This longitudinal study included 477 patients treated with 1420 implants. Medical and dental histories were evaluated in all patients. The location, size, connection type, surgical protocol, use of prosthesis splinting and fixation type were evaluated for each implant. In peri-implant evaluation, minimum keratinized tissue width around implants, peri-implant probing depths, peri-implant bleeding and peri-implant suppuration were assessed. Bone resorption around implants was evaluated with intraoral radiographs at baseline and at follow-up examinations. The study endpoint was peri-implantitis, which was defined as the presence of bleeding on probing and/or suppuration with bone resorption >1mm, in accordance with previous studies. Data were analyzed with mixed-effects Cox models. RESULTS: Peri-implantitis occurred in 15.3% of patients and 9.2% of implants. The overall 5- and 10-year cumulative implant survival rates were 0.95 (95% confidence interval [CI]: 0.93-0.96) and 0.83 (95% CI: 0.8-0.87), respectively. Age (hazard ratio [HR]=0.94, 95% CI: 0.90-0.98, p<0.01), plaque control record >20% (HR=2.61, 95% CI: 1.02-6.67, p=0.04), maxillary placement (HR=1.90, 95% CI: 1.11-3.23, p=0.02) and number of occlusal supports (HR=0.87, 95% CI: 0.77-0.99, p=0.03) were significantly correlated with peri-implantitis development. CONCLUSIONS: Within the limitations of this longitudinal study on risk indicators for peri-implantitis, age, inadequate plaque control, insertion in the maxilla and less occlusal support of natural teeth correlated with peri-implantitis development.

Photosynthetic electron transfer from reaction center pigment-protein complex in silica nanopores.

A photosynthetic reaction center (RC) pigment-protein complex purified from a thermophilic purple photosynthetic bacterium, Thermochromatium tepidum, was adsorbed to a folded-sheet silica mesoporous material (FSM). The RC has a molecular structure with a 7.0 x 5.0 x 13 nm diameter. The amount of RC adsorbed to the FSM compound with an average internal pore diameter of 7.9 nm (FSM(7.9)) was high at 0.29 gRC/gFSM, while that to the FSM(2.7) (2.7 nm diameter) was low at 0.02 gRC/gFSM, suggesting the specific binding of the RC into the 7.9 nm pores of FSM(7.9). An N(2)-adsorption isotherm study indicated the incorporation of the RC into the 7.9 nm pores. The RC inside FSM(7.9) showed absorption spectra in the visible and infrared regions similar to those of the RC in solution, indicating almost no structural changes induced by the adsorption. The RC-FSM(7.9) conjugate showed the high photochemical activity with the increased thermal stability up to 50 degrees C in the measurements by laser spectroscopy. The conjugates rapidly provided electrons to a dye in the outer medium or showed electric current on the ITO electrode upon the illumination. The RC-FSM conjugate will be useful for the construction of artificial photosynthetic systems and new photodevices.