Since medicines and medical devices have been developed and used on different basis of the laws, it was not easy to develop a hybrid preparation of these and to apply for legal permission. However, now, there is a need to develop medical preparations with novel functions by combining the functions of medicines and medical devices. In this section, development examples of apatite-related devices with various medicines are represented as new hybrid pharmaceutical preparations with high functional drug release and/or biocompatibility. Examples; drug release from self-hardening apatite bone cement, creation of osteoporosis condition dependent drug delivery system, cell scaffold construction study with biodegradable apatite / collagen composite cement and cell activity dependent drug release mechanism consisting of apatite cement Gene delivery system.

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Prosthodontic treatments with dental implants are currently clinically effective and predictable. Although all the clinicians are using antibiotics at the implant placement surgery, majority of them are not concerning minimum dose to prevent infections and disadvantages of using antibiotics. I reviewed the clinical studies of antibiotics application in implant placement surgery and proposed a proper antibiotic application with a mouthwash in implant placement surgery.

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Dental implants are one of the effective ways to replace missing teeth. Although favorable long-term results of implant therapy have been reported, the incidence of biological complications occurred around periimplant tissues has also increased. Peri-implantitis and peri-implant mucositis are thought to be caused by dysbiosis in bacterial biofilm, and inflammatory tissue destruction around the implant progresses due to the disruption of homeostasis. For a long time, many researchers have considered that bacterial pathogens related to peri-implant diseases are similar with those of periodontitis. Recently, we tried the comprehensive analysis of microbiota using next-generation sequencing technique and found the difference of interacting core taxa between peri-implantitis and periodontitis. Besides, there were several species frequently found at the sites with peri-implantitis, suggesting that they would play important roles in the dysbiotic biofilm related to peri-implantitis. Systemic conditions such as smoking habit and/or presence of diabetes mellitus are possibly associated with the development of peri-implantitis, while it is inconclusive as established risk indicators. In the consensus report from the 2017 World Workshop held by the American Academy of Periodontology and European Federation of Periodontology, a history of severe periodontitis, poor plaque control, and no regular maintenance care after implant therapy were listed as the rational risk indicators of peri-implantitis. The treatment of peri-implantitis is mainly focused on infection controls. Although the treatment of peri-implantitis is generally carried out according to the treatment for periodontitis, its predictability is not high. Both surgical and non-surgical techniques have been proposed, however, there is still no specific recommendation for the treatment for peri-implantitis. At present, therefore, it would be important to prevent and find the diseases at an early stage by follow-up care

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Gingiva is part of the soft tissue lining of the mouth which surrounds and protects the teeth. In the gingiva there are some unique structures which are essential for wound healing and repair. One of the characteristics of gingiva is to stimulate osteogenesis owing to mesenchymal stem cells (MSCs) contained in the tissue. In this study, we developed a method to isolate mouse gingiva-derived stem cells and characterize these cells for MSCs properties in detail. The results showed that gingivaderived MSCs (GMSCs) showed spindle-shaped fibroblast-like morphology and adherence to plastic. Furthermore, the GMSCs were able to differentiate into multi-lineages (osteogensis, adipogensis, chondrogensis), and strong expression of CD90 and CD105, but lack of CD19 and CD45, was detected by flow cytometry. Expression of two gingiva-dependent miRNAs: miR-146a and miR-155 were observed by RT-qPCR. Supported by these results, it was indicated that gingiva-derived stem cells might be a promising source in tissue engineering.

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There are anatomical limitations in posterior maxilla and mandible for treating with dental implants. Short implant has recently gained a great attention to avoid complications associated with implant treatment in these regions. Although clinical studies with short implants in these regions have been reported, real outcomes of short implants have not been clear yet. The purpose of the present study was to evaluate implant treatments with short implants (6 and 8 mm in length) and long implants (9, 11, 13 mm in length) in posterior molar regions retrospectively. This clinical study was approved by the ethical committee of the institute. Forty five patients received 48 short implants whereas 59 patients received 110 long implants. After a sufficient non-loaded period, 2-3 months in mandible and 4-5 months in maxilla, the secondary surgeries were performed and the final prostheses of cement fixation were delivered. Clinical assessments were done three years after delivering the final prostheses. All the procedures from the surgeries, the prosthodontic steps and the maintenances were performed by the first author. At the secondary surgery, 6 short implants did not integrate with bone, in which 2 implants were placed in the very hard mandibular bone and other 4 implants were exposed after the surgery resulting in extensive bone loss. Four long implants also did not integrate with bone at the secondary surgery, which were also placed in hard mandibular bone. In the osseointegrated 42 short implants, 20 implants were single crown restorations whereas 22 implants were splinted. At 3 years all the 42 short implants were functioning. Radiographically, the periimplant bone loss around the short implants and the long implants was 0.14 ± 0.29 mm and 0.29 ± 0.61, respectively (mean ± SD) Although the 6 short implants were not osseointegrated, these failed cases could be avoided with more surgical attentions. The results of the present study indicate that implant treatments with short implants in posterior regions of anatomical restrictions are clinically effective.

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In order to secure the initial fixation for implanting an implant, obtaining mechanical interdigitations between the implant and a bone is a critical element. For that reason, at the initial fixation of the implanted implant, understanding the stress distribution on the implant and jawbone is clinically necessary. In this research, we fabricated CAD data based on the actual CT images, and by using the finite element method, we examined the stresses generated in the jawbone and implant during the initial fixation of the implant by the SAT (Step Adaptation Technique) method. We fabricated two types of analysis models: normal drill hole and the SAT method, and reproduced it on CAD. As a result of the finite element analysis, by using the SAT method, the stresses were increased by about five times the maximum on the jawbone and about six times the maximum on the implant compared to the normal drill hole. This suggests that the SAT method is an effective method for securing the initial fixation of the implant.

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