レジンコンポジットで再膜処理したファイバーポストの破折抵抗性に及ぼすポストの長さと残存根組織の影響

Effect of length post and remaining root tissue on fracture resistance of fibre posts relined with resin composite.

抄録

レジンコンポジットレジンでリライニングしたファイバーポストで修復した歯根の破折抵抗に及ぼすポストの長さと残存歯根組織の量の影響を検討する。90本の上顎犬歯を9群（n=10）に分けた。2/3群は長さ10mm，1/2群は長さ7～5mm，1/3群は長さ5mmとした．各グループは、残存歯根組織の量（2mm、1mm、0～5mmの太い歯根）によって3つのサブグループに分けられた。ファイバーポストはレジンコンポジットレジンで再固着され、すべての歯は金属冠で修復された。試料を万能試験機で角度135°，速度0-5mm min(-1)で破壊抵抗試験を行った．破壊モードが観察され，破壊抵抗のデータはanovaおよびTukey's（α＝0-05）に供された．その結果，ポスト長さの違いによる破壊抵抗の統計的有意差は認められなかった（P>0-05）．残存象牙質厚さ2mmと1mmでは破折抵抗に統計学的な差はみられず（P＞0-05），0-5mmでは0-5mmより高かった（P＜0-05）．修復可能な破壊の有病率はすべての群で観察された。このことから，レジンコンポジットレジンでリライニングされたファイバーポストの長さは耐破折性に影響しないが，厚さは歯内療法歯の修復に重要な因子であると結論できる．

To investigate the influence of post length and amount of remaining root tissue on the fracture resistance of roots restored with fibre posts relined with resin composite. Ninety upper canine teeth were divided into nine groups (n = 10). The post spaces were prepared resulting in different lengths, as follows: group 2/3, preparations with lengths of 10 mm; group 1/2, preparations with lengths of 7·5 mm; and group 1/3, preparations with lengths of 5 mm. Each group was divided into 3 subgroups according to amount of remaining root tooth tissue (2, 1 mm or 0·5 mm of thick root). Fibre posts relined with resin composite were cemented, and all teeth were restored with metal crowns. The samples were submitted to the fracture resistance test in a universal testing machine, at an angle of 135° and speed of 0·5 mm min(-1) . Failure modes were observed and the data of fracture resistance were submitted to the anova and Tukey's (α = 0·05). No statistically significant difference in fracture resistance was found among different post lengths (P > 0·05). Remaining dentin thickness of 2 and 1 mm did not differ statistically in fracture resistance (P > 0·05), which was higher than of 0·5 mm dentin thickness (P < 0·05). A prevalence of repairable failure was observed in all groups. It can be concluded that the length of fibre post relined with resin composite did not influence fracture resistance, but thickness was an important factor for the restoration of endodontically treated teeth.