Evaluation of peri-implant tissue in nonsubmerged dental implants: a multicenter retrospective study.

OBJECTIVES: The objective of this study was to evaluate the peri-implant's hard and soft tissue response associated with the 1-stage, nonsubmerged, endosseous dental implant. STUDY DESIGN: A multicenter retrospective clinical evaluation was performed on 339 nonsubmerged implants placed in 108 patients at 5 clinical centers between January 2003 and December 2007. RESULTS: After a mean follow-up period of 30 months, the mean crestal bone resorption in 339 implants was 0.43 mm. The survival and success rates were observed to be 99.1% and 95.1%, respectively. The mean calculus, inflammatory, and plaque indices were 0.13, 0.37, and 0.73, respectively, and the mean width of buccal keratinized mucosa was observed to be 2.43 mm. CONCLUSION: The short- to intermediate-term evaluation of the 1-stage, nonsubmerged, endosseous implant yields relatively high survival and success rates.

Cryopreservation of human teeth for future organization of a tooth bank--a preliminary study.

This study was aimed at evaluating whether cryopreserved teeth can be used for future transplantation by examining the viability and differentiation capability of periodontal ligament (PDL) cells and measuring the hardness of dental hard tissue. Fifty-four teeth were divided into two groups, control and frozen teeth. A MTT assay and a TUNEL assay were performed for the examination of the viability and apoptotic death of PDL cells. Immunohistochemical staining for alkaline phosphatase was performed to observe whether the differentiation capability of PDL cells was maintained by the freezing and thawing procedure. Hardness was measured to detect whether dental hard tissue was affected by the freezing conditions. The MTT and TUNEL assays showed no significant difference in the viability of PDL cells between the two groups. The differentiation capability of PDL cells was maintained in frozen teeth as evidenced by alkaline phosphatase staining. The hardness of frozen teeth was not changed, but a longitudinal fracture was found in 25% of the frozen group. The viability and differentiation capability of PDL cells were maintained in a frozen environment; however, it is thought that a new cryopreservation method preventing fracture of dental hard tissue should be developed for clinical application.

Construction of DNA-shuffled and incrementally truncated libraries by a mutagenic and unidirectional reassembly method: changing from a substrate specificity of phospholipase to that of lipase.

A method of mutagenic and unidirectional reassembly (MURA) that can generate libraries of DNA-shuffled and randomly truncated proteins was developed. The method involved fragmenting the template gene(s) randomly by DNase I and reassembling the small fragments with a unidirectional primer by PCR. The MURA products were treated with T4 DNA polymerase and subsequently with a restriction enzyme whose site was located on the region of the MURA primer. The N-terminal-truncated and DNA-shuffled library of a Serratia sp. phospholipase A(1) prepared by this method had an essentially random variation of truncated size and also showed point mutations associated with DNA shuffling. After high-throughput screening on triglyceride-emulsified plates, several mutants exhibiting absolute lipase activity (NPL variants) were obtained. The sequence analysis and the lipase activity assay on the NPL variants revealed that N-terminal truncations at a region beginning with amino acids 61 to 71, together with amino acid substitutions, resulted in the change of substrate specificity from a phospholipase to a lipase. We therefore suggest that the MURA method, which combines incremental truncation with DNA shuffling, can contribute to expanding the searchable sequence space in directed evolution experiments.