骨増生の研究は，バイオエンジニアリングと再生医工学において，骨欠損を修復させることからインプラント治療にとって非常に重要である．従来から，ハイドロキシアパタイト，β-TCP または炭酸アパタイトを用い，コラーゲンまたはゼラチンで製作した複合体による骨形成の研究は行われている．しかしながら，炭酸カルシウムを用いる研究は少ない．われわれは，北海道において十分に活用されていない資源であるホタテガイの貝殻の炭酸カルシウム（CCSS）と，サケコラーゲン（SAC）によって作られた複合体の骨増生材料として研究を行った．
ウシコラーゲンとSAC は電子顕微鏡によって，形態的な比較を行った．SAC 単体とSAC＋CCSS 複合体は，一晩凍結乾燥された．それらの比率は1.4 mL のSAC に0 g または0.014 g のCCSS が含まれた．SACと0.014 g CCSS 含有のSAC 複合体は，4週間の雄ウイスター・ラットの頭頂骨に埋入し2週間後，頭頂骨は複合体とともに摘出され，ヘマトキシリン・エオジン染色法とアザン・マロリー染色法で染色した．
SAC 構造はウシのものと同様に観察された．しかし，SAC コラーゲン線維はウシのものより多孔性であった．組織学的標本では，新生骨様形態がそれぞれの実験群で確認された．新生骨様形態は対照群には観察されなかった．0.014 g CCSS 含有の複合体は，SAC単独と比較して新生骨様形態が多かった．また，実験群と対照群には骨膜の肥厚が観察された．
本研究は，スペースが骨形成のために保たれるならSAC とCCSS によって新生骨様形態を確認することができた．さらに，本研究は産業廃棄物を研究に用いるという新しい試みである．

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It is clear that sufficient osseointegration markedly influences the prognosis of implant therapy. One problem that is yet to be resolved is the development of a therapy to promote rapid and reliable implant osseointegration. However, there have been few reports investigating the cell biological mechanisms of implant osseointegration. Recently, several experiments demonstrated that carbon dioxide (CO₂) laser irradiation as well as mechanical force could stimulate bone regeneration. Given that laser irradiation can induce bone formation, it has been postulated that CO₂ laser irradiation may be applicable to implant therapy in order to promote rapid and reliable osseointegration. This study examined the effects of CO₂ laser irradiation on implant osseointegration. Sprague-Dawley rats underwent titanium implant insertion at the proximal tibiae and then 24 hours after the implant placement, and CO₂ laser irradiation (0.5 W, 60 sec, 30 J) was performed at region of the left tibiae where the implants were inserted (laser group), while implants inserted in the right tibiae did not receive laser irradiation and served as the control group. Two weeks after the surgery, removal torque values of the laser group were significantly higher than those of the control group, but the values in both groups were equivalent 1 and 4 weeks after surgery. Sections of tibiae obtained 2 weeks after surgery showed that large amounts of bone tissue had formed around the implants in the bone marrow region in the laser group, whereas small amounts of bone tissue could be seen in sections from the control group. Interestingly, osteocytes in the bone tissue formed around the implants in the laser group showed a remarkably decreased immunohistochemical reaction for sclerostin as compared with osteocytes in the control group. Mineral appositional rate on bone histomorphometric examination using calcein labeling demonstrated much higher values in bone tissues formed around the implants in the laser group than those in the control group 2 weeks after surgery. These results indicate that bone formation around the implants was stimulated and maturation was accelerated by CO₂ laser irradiation. In conclusion, these findings suggest that CO₂ laser irradiation could be useful for implant therapy.

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The purpose of this study was to evaluate the biological effects of dental rinses and dental pastes on titanium-surface properties. Titanium discs were totally covered with commercially available dental rinses or pastes, then the specimens were incubated for two or ten days, respectively. The alterations of color stability and surface roughness before and after the incubation with the dental rinses and pastes were analyzed by a color-difference meter and surface roughness meter, respectively. In addition, the mRNA expressions of CCL2 in human gingival fibroblast cells (hGFB) were investigated when the cells were cultured on the surface of the titanium discs treated with the dental pastes. By biofilm assay using an ATP analyzer, the biofilm formation of Porphyromonas gingivalis on the surface of the titanium disc was examined. There were no significant differences in color stability or surface roughness of the titanium surfaces among all dental rinses. Similarly, dental pastes showed no significant change in color stability or surface roughness. On the other hand, sodium fluoride alone significantly increased color stability, as compared with those of dental pastes examined here ( ANOVA, p＜0.05). The titanium surface after incubation with dental pastes had no effect on the mRNA expression of CCL2 in hGFB and biofilm formation of P. gingivalis. The in vitro data in the present study, taken together, suggested that dental rinses of pH: 4.1～7.4 and dental pastes with and without commercially available fluoride could be used daily by patients treated with dental implants. However, care should be taken in the case of prolonged usage since sodium fluoride might be involved in corrosion of the titanium surface.

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Objectives: This study evaluated the application of low-intensity pulsed ultrasound (LIPUS) to reduce the implant healing time in rat tibiae.
Materials and Methods: Forty-two 10-week-old female Sprague-Dawley (SD) rats were used in this study. Titanium implants were inserted into the proximal tibiae of all rats. After installation, LIPUS irradiation was performed for 15 min on the left tibiae. LIPUS therapy was repeated every other day for 2 weeks, i.e., a total of 3 times for a 7-day observation group and 7 times for 28-day observation group. Animals were sacrificed and tibiae were collected 8 and 28 days after implant placement. After capturing soft X-ray images and performing a torque test, the tibiae were decalcified and 8-µm-thick sections were prepared. Specimens were stained with hematoxylin and eosin, Masson-Goldner stain, TRAP stain, and immunohistochemical staining with anti-SOST and PECAM antibodies.
Results: Soft-X ray images, removal torque values, and histomorphometric analysis demonstrated a significantly higher degree of bone formation in the LIPUS group earlier in the healing process. This phenomenon was observed continuously until 28 days. Bone maturation and angiogenesis were also promoted by LIPUS treatment.
Conclusion: LIPUS irradiation was effective in bone healing and osseointegration of titanium implants inserted into rat tibiae. LIPUS may also be suitable for use in oral implant therapy.

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Many previous clinical studies have reported the successful application of dental implants for functional reconstruction of edentate and partially edentate jaws. However, few of those studies focused on the Japanese population. In fact, most of the studies that focused on the Japanese population were cross-sectional in design or excluded patients who were lost to follow-up; therefore, the findings from such studies have low reliability. Moreover, the studies focused on implant survival after the insertion of superstructures, and very few studies have separately investigated the acquisition and maintenance of osseointegration.
The purpose of the present study was to build a useful database to help patients choose the most appropriate treatment. It was a follow-up study based on existing clinical records, and covered all participants and implants. In this study, we analyzed the survival rate and clearly investigated separately the acquisition and maintenance of osseointegration.
The rate of acquisition of osseointegration was calculated by dividing the number of implants acquired by the total number of implants placed. The rate of maintenance of osseointegration was evaluated using life-table analyses, which included an intention-to-treat parameter.
The study consisted of a consecutive series of 161 women and 56 men (mean age: 60.3±9.5 years) who received osseointegrated dental implants at the Department of Dentistry and Oral Surgery, Yata Cooperative Clinic, from January 1999 to December 2010. A total of 637 implants were placed.
About 625 implants acquired osseointegration, and functioned with superstructures; 5 of these implants failed to maintain osseointegration. Around 40 implants were lost to follow-up (rate of tracing: 93.6%). The rate of acquisition of osseointegration was 98.1%, while that of maintenance of osseointegration for 12 years was 99.1%. Thus, we conclude that follow-up surveys on the long-term prognosis of dental implants should be conducted more frequently to expand the available clinical data on this subject.

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