Journal Article 炭酸カルシウムまたはα-TCPを複合化した4-META/MMA-TBBレジン上への新生骨の接触

柳澤, 剛  ,  菅谷, 勉  ,  川浪, 雅光

36 ( 2 )  , pp.54 - 62 , 2016-03 , 北海道歯学会
4-META/MMA-TBBレジンは優れた接着性と生体親和性を有することから,歯根端切除術や垂直歯根破折の接着治療,髄床底穿孔部の封鎖などに応用されてきたが,レジン上への硬組織の形成はできていないのが現状である.一方で,4-META/MMA-TBBレジンに炭酸カルシウムを添加すると,骨との結合を促進させることが示唆されている.そこで,本研究では4-META/MMA-TBBレジンにα-TCPおよび炭酸カルシウムを複合化させ,大腿骨骨髄腔に移植して新生骨との接触状態などを評価した.  4-META/MMA-TBBレジンを硬化させて円柱形試料を作製し,炭酸カルシウムまたはα-TCPをそれぞれ0,40,60wt%で複合化したスーパーボンドポリマー粉末を,モノマー液とキャタリストに混和し,円柱形試料表面に塗布,Wistar系雄性ラットの左右大腿骨骨髄腔に穿孔して埋植した.術後2,8週で大腿骨を採取,脱灰薄切標本を作製してH-E染色し,試料底部と骨との接触率などを計測した.  2週後,すべての群で試料周囲に新生骨が形成されていたが,新生骨と試料が直接接している部分はほとんどなかった.8週後には試料と骨が直接接している部分もみられ,接触率はコントロール群は2.6±0.5%(中央値±四分位偏差),炭酸カルシウム40%群は0±4.8%,炭酸カルシウム60%群は0%,α-TCP40%群は14.0±5.0%,α-TCP 60%群は28.3±14.4%で,α-TCP40%群はコントロール群と炭酸カルシウム60%群に比較して有意に高く,α-TCP60%群はコントロール群と炭酸カルシウム40%および60%群より有意に高かった.  以上より,4-META/MMA-TBBレジンにα-TCPを複合化すると,レジンと骨との直接接触が高まることが示唆された.
4-META/MMA-TBB resin (SuperBond, Sun Medical) has been used for root-end sealing following apicoectomy and the bonding treatment of vertical root fractures as it results in high strength and biocompatible. However hard tissue is rarely formed by the resin. New bone formation was reported to have been observed directly on cured resin containing calcium carbonate. In this study, we evaluated bone formation on the surface of 4-META/MMA-TBB resin containing calcium carbonate or α-TCP.  To create the implantation rods, SuperBond was cured anaerobically in a polypropylene tube that was 1 mm in diameter and broken into segments that were 5 mm in length. The right and left femur of Wistar rats were trephined to create a medullary cavity that was 1 mm in diameter, and the rods were implanted after resin was applied : calcium carbonate or α -TCP were mixed with the polymer powder of SuperBond at 0, 40, and 60 wt%, and then mixed with monomer and an initiator. Histological specimens were prepared at 2 and 8 weeks post-operation and the sections were stained with H-E. Measurements including both the rates of bone formation and the direct contact of new bone with the resin were taken.  Two weeks following implantation, newly-formed bone was observed in the surrounding area of the implanted rods, and few inflammatory cells were found in the five groups. Newly formed bone was not directly in contact with the samples. The soft tissue was thin at eight weeks. The newly formed bone was directly in contact with all samples. The rates of bone-resin contact were 2.6±0.5% (0% group), 0±4.8% (calcium carbonate 40% group), 0% (calcium carbonate 60% group), 14.0±5.0% (α-TCP 40% group), 28.3±14.4 (α-TCP 60% group) respectively. The α-TCP 40% group showed a statistically significant difference compared with the 0% and the calcium carbonate 60% group. The Theα-TCP 60% group showed a statistically significant difference compared with the 0%, the calcium carbonate 40% and 60% group.  These results suggested that α-TCP filler in cured 4-META/MMA-TBB resin can facilitate direct contact with bone.

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