歯科用陶材の表面粗さに及ぼす2種類の研磨方式とリグレイジングの影響

Effects of 2 polishing techniques and reglazing on the surface roughness of dental porcelain.

抄録

本研究の目的は，触針式プロフィロメーターと走査型電子顕微鏡を用いた表面粗さの定量的・定性的分析により，歯科用陶材の2種類の研磨方式とリグレーズの効果を比較することである．15個のポーセレン試料（10 x 3 x 3 mm）が使用された．各ブロックの1面に釉薬を塗布し，表面粗さ(Ra)を分析した．すべての試料を酸化アルミニウム製サンドペーパーで光沢がなくなるまで研磨し，その結果得られたRa値を求めた。その後，無作為に3つの処理群に分けた（n = 5）。グループ I（GI）はダイヤモンド含浸ゴム砥石で研磨，グループ II（GII）は炭化ケイ素含浸ゴム砥石で研磨，グループ III（GIII）はリグレーズ焼成のみであった。処理後，新たにRaの測定を行った。データは分散分析（ANOVA），および5%でのTukey検定に供した。素地と処理面の比較は，paired t-testで行った．研削面および処理面のRa値（μm）は以下のように決定された．GI: 0.66 ± 0.14, 0.35 ± 0.06; GII: 0.60 ± 0.04, 0.09 ± 0.03; GIII: 0.67 ± 0.05, 0.75 ± 0.24 であった。すべての群について，地上と処理後の値に有意な差が認められた。処理後では、すべてのグループで統計的に差が見られた（P < 0.05）。ダイヤモンド含浸ゴムによる研磨やリグレーズのみでは十分な平滑性を得ることができなかったが，炭化ケイ素システムにより初期の平滑性が再確立された．

The aim of this study was to compare the effect of 2 polishing systems and reglazing of dental porcelain through a quantitative and qualitative analysis of surface roughness using a stylus profilometer and scanning electron microscope. Fifteen porcelain specimens (10 x 3 x 3 mm) were used. On 1 surface of each block, a layer of glaze was applied, and surface roughness (Ra) was analyzed. All specimens were ground with aluminum oxide sandpaper until the shine was removed and the resulting Ra values were obtained. Afterwards, they were randomly divided into 3 treatment groups (n = 5): Group I (GI), polished with diamond-impregnated rubber wheels; Group II (GII), polished with silicon carbide-impregnated rubber wheels; and Group III (GIII), reglazed firing procedure alone. After the treatments, new Ra measurements were done. Data were submitted to analysis of variance (ANOVA), and Tukey tests at 5%. Comparisons between ground surface and treated surface were made by paired t-test. The ground and treated Ra values (µm) were determined as follows: GI: 0.66 ± 0.14, 0.35 ± 0.06; GII: 0.60 ± 0.04, 0.09 ± 0.03; and GIII: 0.67 ± 0.05, 0.75 ± 0.24. Significant differences were found between the ground and treated values for all groups. After the treatments, all groups differed statistically (P < 0.05). The silicon carbide system re-established the initial surface smoothness, while polishing with diamond-impregnated rubber or reglazing alone were not able to achieve a satisfactory smoothness.