背景：ウシ真皮由来の生体吸収性コラーゲンスポンジと，多孔性ベータ型リン酸三カルシウム（β-TCP）小顆粒からなる複合体は良好な臨床的操作性，優れた骨伝導能と生体内崩壊性を示す可能性がある．
目的：本研究の目的は，動物実験と細胞培養実験モデルを用いて，β-TCP コラーゲン複合体の組織学的，細胞生物学的性質を示すことである．
材料と方法：β-TCP コラーゲン複合体もしくは対照のコラーゲンスポンジを，直径5.0 mm のラット頭蓋骨欠損へ埋入した．術後2，4および8週に組織学的評価を行った．ラット大腿骨骨髄由来骨芽細胞様細胞を，ポリスチレン培養皿上で物理的接触がないように，β-TCP コラーゲン複合体もしくは対照コラーゲンスポンジとともに共培養した．
結果：治癒初期に，β-TCP コラーゲン複合体は，生体内崩壊とともに，材料内外から骨芽細胞と結合組織様組織の侵入を受けた．最終的に，β-TCP コラーゲン複合体は埋入部位の体積を減少させずに緻密で厚い成熟骨組織に置換された．一方，対照コラーゲンスポンジを埋入した骨欠損内では，薄い線維様組織のみ観察された．β-TCP コラーゲン複合体は，対照コラーゲンスポンジよりも，共培養した骨芽細胞様細胞のアルカリフォスファターゼ活性やvon Kossa 陽性石灰化基質産生量，細胞内カルシウムレベルを上昇させた．
結論：β-TCP コラーゲン複合体は，ラット頭蓋骨クリティカル・サイズ骨欠損において，治癒初期には材料内部で骨梁形成をうけ，その後，成熟骨組織に完全に置換された．さらに，β-TCP コラーゲン複合体はカルシウムの供給を通じて骨芽細胞様細胞の分化を刺激することが示唆された．これら所見は，β-TCP コラーゲン複合体の優れた骨伝導性，生体内崩壊性および骨刺激活性を支持するものであった．

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Rotational panoramic radiography is routinely used in dental practice. It has not been clarified, however, whether an accessory mental foramen can be demonstrated using this technique. The visibility of accessory mental foramina on rotational panoramic radiographs, including the influence of dry mandibles and their positioning, was compared with that on para-panoramic images reconstructed from cone-beam computed tomography (CBCT).
Four mandibular bones with accessory mental foramina were analyzed. Para-panoramic images were reconstructed from CBCT images with the accessory mental foramen using three-dimensional visualization and measurement software, and then the accessory mental foramen on rotational panoramic images was compared with that on para-panoramic images.
There was a difference in the rate of visualization of the accessory mental foramen on rotational panoramicradiographs from 20% to 95%.
These results indicated that some of the accessory mental foramen could be observed on rotational panoramic radiographs.

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Metal ceramic restorations with high-gold alloys have been used for crowns and fixed dental prostheses (FDPs). Today, however, high-gold alloys have been largely replaced by cobalt-chromium alloy (Co-Cr alloy) for the FDP framework of the implant superstructure, due to the low cost and favorable mechanical properties such as high strength, high modulus of elasticity as well as high corrosion resistance. When fabricating the superstructure, it is necessary to use high-fusing gold solder for joining the Co-Cr alloy framework to the gold cylinder. However, the strength of solder joints between Co-Cr alloy and high-fusing gold solder has not been fully clarified. This study aimed to evaluate the tensile bond strengths of Co-Cr alloys that were joined with high-fusing gold solder in comparison with conventional gold alloys joined with high-fusing gold solder. In addition, scanning electron microscopy (SEM) of the fractured surface and electron probe microanalysis (EPMA) of the joint interface were performed.
The tensile bond strengths of Co-Cr alloy joined with high-fusing gold solder were more than 600 MPa, and were significantly larger than those of metal-ceramic gold alloys joined with high-fusing gold solder. The cohesive fracture pattern in solder was observed in the fractured surface of all specimens by SEM observation. EPMA analyses revealed that the elements of the gold solder had diffused into the Co-Cr alloy, leading to firm bonding between the alloy and solder.
These results indicated that the joining technique of Co-Cr alloy using a high-fusing gold solder is promising for fabricating implant superstructures.

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本研究では，ラット頭蓋骨の骨膜下に連通多孔体ハイドロキシアパタイトであるネオボーン^®（NB），または連通多孔体β-トリリン酸カルシウムであるオスフェリオン^®（OS）を埋入し，骨の治癒過程を伴わない骨造成の観察を行った．NB は非吸収性であり，OS は吸収性である．
NB とOS は連通多孔体構造を有している．走査電子顕微鏡観察の結果，NB の直径約100～200μm の大きさの微小気孔は，球形で均一的な形状をしていた．OS の微小気孔は不均一な形状をしており，その数はNB よりも少ないことが分かった．NB とOS のエックス線解析パターンから，それぞれ両者とも純度の高いハイドロキシアパイトとβ-トリリン酸カルシウムであることがわかった．
埋入したNB，OS のラット頭蓋骨骨膜空隙の中央付近にカルセインによる蛍光標識がみられ，両材料とも骨の誘導はラットの頭蓋骨表面から起こり，骨膜側からは起こっていなかった．埋入後4 週と8 週経過後では，NB とOS のグループの間で緑のラベリング線の長さに統計学的に有意差はみられなかった．（p＞0.05）
NB とOS の両グループの骨造成の組織学的観察でも，ラットの骨膜側からではなく頭蓋骨表面側から新生骨の形成が認められた．術後4 週では新生骨形成はNB，OS ともに非常に少なく部分的であった．術後8 週では，連通多孔の内部に成熟した骨形成が確認できた．NB では術後4 週から8 週にかけて，材料の寸法変化は全くみられなかった．一方，OS では埋入期間中，試材の吸収のため試料の高さが約8～9％減少した．術後4 週までのNB とOS の新生骨形成の割合は約5％程度であった．術後8 週では，両材料ともに，統計学的に有為な新生骨形成の増加がみられた（p＜0.05）．8 週目ではOS はNB に比較して統計学的に有意に高い割合の骨形成を示した（p＜0.05）．
以上，ラット骨膜挙上モデルを用い非吸収性多孔性リン酸カルシウムセラミックと吸収性リン酸カルシウムセラミックの骨造成の違いが確認でき，体積は減少するものの，連通多孔性の吸収性がより多くの骨造成に関与することがわかった．

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Purpose: The purpose of the present clinical study was to examine the effect of differences in the surface materials of implants on the achievement of osseointegration and its long-term maintenance during a 10- to 15-year follow-up for two systems of cylinder implant, titanium implant and hydroxyapatite-coated implant, which were used for the prosthesis of posterior partially edentulous jaws.
Materials and Methods: The study evaluated 221 titanium implants in 75 patients (Ti implants) and 181 hydroxyapatite-coated implants in 66 patients (HA im plants), all of which were installed in available bone of posterior partially edentulous jaws during the period from 1994 to 1999 at a single center in Japan. The cumulative survival rates after 10 to 15 years were calculated by life table analysis and compared to evaluate the clinical courses.
Results: The cumulative survival rates after 10 to 15 years were 94.2% for Ti implants and 92.5% for HA implants, showing no significant difference in survival rate between the different implant bodies.
On comparison of survival rates of the implant bodies by elapsed period, Ti implants and HA implants showed 99.5% and 99.4%, respectively, for less than one year post-implantation, and 92.2% and 89.5%, respectively, for one year or more post-implantation, demonstrating no significant difference in survival rate during either period. However, in both implant bodies the survival rate tended to decrease over time at 4 to 5 years after loading.
In addition, incidence rates of implantation failure during the elapsed period showed no significant difference between Ti implants and HA implants in the cases of implant loss due to failed osseointegration, with 0.5% and 0.6%, respectively, during the post-implantation period of less than one year. Meanwhile, after one year or more post-implantation, the incidence of implant loss due to failed osseointegration was 6.1% for Ti implants and 0% for HA implants, and the incidence of implant loss due to peri-implantitis was 1.7% for Ti implants and 10.5% for HA implants, demonstrating a significant difference in incidence rate between the different implant bodies.
Discussion and Conclusion: No significant differences were found in the long-term survival rates between Ti implant bodies and HA implant bodies.
In addition, while both types of implant body showed successful survival rates during a post-implantation period of less than one year, at one year or more after implantation, the survival rates tended to decrease over time due to the development of failed osseointegration in Ti implants and the occurrence of peri-implantitis in HA implants.
Thus, it is suggested that, in order to achieve better long-term outcomes, occlusal adjustment for avoiding overloading on specific implant bodies is important for Ti implant bodies, whereas maintaining good oral hygiene for avoiding peri-implantitis is important for HA implant bodies, during a follow-up period of one year or more.

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Purpose: To evaluate the sinus lift procedure in conjunction with autogenous bone harvested from the mandible.
Materials and Methods: The study group comprised 10 patients who underwent a total of 11 sinus lift procedures. The donor sites in the mandible included the symphysis, ramus or retro-molar region. Each implant site was radiographically evaluated preoperatively; at superstructure placement 6 to 10 months later; and 1, 2, 3, 5, and 10 years after loading. Panoramic radiography and cross-sectional imaging were performed as needed. Preoperative bone height was measured to determine the distance between the primitive sinus floor and the crest of the alveolar ridge. Postoperative bone height was measured to determine the distance between the sinus floor after the sinus lift procedure and the crest of the alveolar ridge and the apical end of the implant body in the area. We analyzed the difference of measurement using two way ANOVA with IBM SPSS, and analyzed the difference of the average value with multiple comparisons (Tukey). The change in bone density was also observed on the radiograph.
Results: The average distance between the primitive sinus floor and the crest of the alveolar ridge in the plan of the implant placement area was 3.5±1.4 mm. The mean distance between the sinus floor after the sinus lift procedure and the crest of the alveolar ridge was 12.4±1.6 mm at the time of superstructure placement and 11.8±1.9 mm and 11.3±1.9 mm after 1 and 10 years of loading, respectively. The distance between the sinus floor after the sinus lift procedure and the apical end of the implant body was 1.6±1.2 mm at the time of superstructure placement and 1.4±1.5 mm and 1.0±1.8 mm after 1 and 10 years of loading, respectively. A statistical significance was detected between at the time of superstructure placement and after 10 years. Regarding the change in bone density, in 5 of the 11 sinuses, the grafted bone was highly radiopaque compared to the native bone at the time of superstructure placement, but it showed the same density as that of the native bone about 2 years after loading.
Conclusion: The height of the grafted bone decreased gradually, and its rate was very low. The change in density of the grafted bone was approximately stable between 1.5 to 2.5 years. This appearance was maintained during the observation.

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