Characterization of bioactive substances involved in the induction of bone augmentation using demineralized bone sheets.

PURPOSE: To investigate the bone augmentation ability of demineralized bone sheets mixed with allogeneic bone with protein fractions containing bioactive substances and the interaction between coexisting bioactive substances and proteins. METHODS: Four types of demineralized bone sheets mixed with allogeneic bone in the presence or absence of bone proteins were created. Transplantation experiments using each demineralized bone sheet were performed in rats, and their ability to induce bone augmentation was analysed by microcomputed tomography images. Bioactive substances in bone proteins were isolated by heparin affinity chromatography and detected by the measurement of alkaline phosphatase activity in human periodontal ligament cells and dual luciferase assays. Noncollagenous proteins (NCPs) coexisting with the bioactive substances were identified by mass spectrometry, and their interaction with bioactive substances was investigated by in vitro binding experiments. RESULTS: Demineralized bone sheets containing bone proteins possessed the ability to induce bone augmentation. Bone proteins were isolated into five fractions by heparin affinity chromatography, and transforming growth factor-beta (TGF-ß) was detected in the third fraction (Hep-c). Dentin matrix protein 1 (DMP1), matrix extracellular phosphoglycoprotein (MEPE), and biglycan (BGN) also coexisted in Hep-c, and the binding of these proteins to TGF-ß increased TGF-ß activity by approximately 14.7% to 32.7%. CONCLUSIONS: Demineralized bone sheets are capable of inducing bone augmentation, and this ability is mainly due to TGF-ß in the bone protein mixed with the sheets. The activity of TGF-ß is maintained when binding to bone NCPs such as DMP1, MEPE, and BGN in the sheets.

Maintenance issues of elderly patients requiring nursing care with implant treatments in dental visiting: position paper.

PURPOSE: Japan, with an increasing number of elderly people needing long-term care in a super-aged society, urgent needs to develop the clinical guidelines on implant maintenance for elderly people with declining independence. The purpose is to categorize the troubles encountered in the care of patients with dental implants and to indicate actual practices and points of note. METHODS: From the members of the Japanese Society of Oral Implantology, 12 expert panelists who were experienced with many problems of implant maintenance during dental visits and were familiar with their solutions were selected. Through repeated discussions in the many panel meetings, the problems of implant maintenance during dental visits were distilled. RESULTS: During a dental visit, the oral cavity, general conditions, and background of elderly patients who cannot orally care for themselves must be grasped, and medical staff, care managers, and patients should understand the changes in these factors as time goes by. The solutions and responses that can be made differ greatly depending on the medical care facilities, the environment, differences in the experience of medical staff, and the patient's background. Thus, it is necessary to select safe treatments appropriate to each situation. CONCLUSIONS: This paper features many opinions based on clinical experiences. However, clinical guidelines on implant management during dental visits should be formulated in the future based on the accumulation of evidence through the implementation of clinical research.

Occlusion accuracy of restorations and removable partial dentures fabricated using the impression under occlusal force with functionally generated path recording.

To evaluate the occlusion accuracy of a novel impression technique, excessively high occlusion and the occlusal contact area during lateral movements were compared between metal restorations (restorations) and removable partial dentures (RPDs) fabricated using conventional and novel techniques. Both restorations and RPDs were fabricated on the simulation model with the precise displacement of the remaining teeth and soft tissue. For the novel technique, functionally generated path (FGP) recording and impression under occlusal force were simultaneously performed using a custom tray with an FGP table. For the two conventional techniques, definitive casts were mounted on an average value articulator and a semi-adjustable articulator in the typical manner. Prostheses were placed on the simulation models, and excessively high occlusion in the intercuspal position and occlusal contact areas during lateral movements were measured. Statistical analyses were performed using Kruskal-Wallis and Steel-Dwass tests (α = 0.05). For both prostheses, conventional techniques showed significantly higher occlusion in the intercuspal position than the novel technique. Moreover, the new technique demonstrated better guidance contact during lateral movements than conventional techniques. This novel technique can be recommended for the fabrication of highly accurate prostheses with appropriate occlusal contact without corrections at delivery.

Bone augmentation around a dental implant using demineralized bone sheet containing biologically active substances.

This study was designed to evaluate the volume of alveolar bone augmentation after immediate implant placement using demineralized bone. We examined the collagen matrix of demineralized bone and biologically active substances contained therein. Rat maxillary first molars were extracted, and the animals were divided into five groups as follows: tooth extraction only, implant into the mesial root socket, implant and other root sockets covered with demineralized bone sheet, implant and other root sockets filled with demineralized bone powder under the sheet, and implant and other root sockets covered with demineralized bone sheet from which proteins were extracted. We ascertained whether biologically active substances are contained in extracted proteins. Biologically active substances were detected in extracted proteins. Conditions using demineralized bone sheet with biologically active substances significantly augmented the height of the alveolar bone. Such resorbable membranes containing biologically active substances hold promise as clinical agents for bone augmentation upon implantation.

Effect of Nerve Growth Factor on Osseointegration of Titanium Implants in Type 2 Diabetic Rats.

PURPOSE: Compared with the general population, a poorer quality of bone-implant osseointegration occurs and at a higher failure rate in patients with type 2 diabetes mellitus. The aim of this study was to analyze the effects of local injection of nerve growth factor at the bone-implant interface after implantation in type 2 diabetic rats. MATERIALS AND METHODS: Goto-Kakizaki (GK) rats (n = 30) were used as a model of type 2 diabetes mellitus, and Wistar rats were used as a control (n = 15). GK rats were assigned randomly into two groups (n = 15/group): the diabetes mellitus group (saline only) and the nerve growth factor group (received nerve growth factor treatment). One titanium implant was placed in each rat's left tibia. Immediately postoperatively, nerve growth factor group rats were injected with nerve growth factor (0.4 µg/day) intramuscularly around the implant, daily for 7 days. Diabetes mellitus and control group rats received normal saline in an identical manner. Rats were sacrificed at 2, 4, and 8 weeks following implant surgery. RESULTS: Traditional light and confocal laser scanning microscopy were used on nondecalcified sections to investigate fluorochrome labeling changes and histologic features of bone adjoining the implants. Bone-to-implant contact and bone volume percentage in the diabetes mellitus group were significantly less than in the control and nerve growth factor groups, with no statistically significant differences between the control and nerve growth factor groups. Confocal laser scanning microscopy showed a significant increase in marked bone around the nerve growth factor group implant at 4 weeks (P < .01) and 8 weeks (P < .05) compared with the diabetes mellitus group. CONCLUSION: This study showed that local injection of nerve growth factor could improve implant-bone osseointegration in diabetic rats and may have important clinical implications.