異なる表面処理が超微粒子ジルコニアの結合能と物理的・機械的性質に及ぼす影響

Effect of different surface treatments on the bonding potential and physical and mechanical properties of ultratranslucent zirconia.

抄録

問題提起:

超透明ジルコニアの強度や透光性を損なわずに接着性を向上させる適切な表面処理を決定するための研究は少ない。

STATEMENT OF PROBLEM: Studies to determine a suitable surface treatment that improves bonding without compromising the strength or translucency of ultratranslucent zirconia are scarce.

目的:

本研究の目的は，異なる表面処理が透光性，表面形状，相変態，二軸曲げ強度，接着強度および耐久性に及ぼす影響を評価することである。

PURPOSE: The purpose of this in vitro study was to evaluate the effect of different surface treatments on translucency, surface topography, phase transformation, biaxial flexural strength, bond strength, and durability.

材料と方法:

合計169個の超透光性ジルコニア円盤を、適用した表面処理によってランダムに4群に分けた：空中粒子研磨（APA）（n=46）、摩擦化学シリカ空中粒子研磨（TS）（n=46）、非熱酸素プラズマ（NTP）（n=46）、無処理、コントロール（C）（n=31）。透光性パラメータ（ΔTP00）は分光光度計（n=15）、相変態はX線回折装置（n=5）、表面形状は走査型電子顕微鏡（SEM）（n=3）、二軸曲げ強度（BFS）は万能試験機（n=15）で評価しました。マイクロシアー接着強さ（μSBS）試験は，8枚の円盤に40枚のコンポジットレジン試験片を貼り付けて万能試験機で試験し，20枚の試験片は24時間後に，20枚の試験片はサーモサイクラー（TC）で熱水老化後に試験した．データは、ANOVAとTukeyポストホックテスト（α=.05）で分析した。曲げ強さとμSBSの結果についてはワイブル解析を行った。

MATERIAL AND METHODS: A total of 169 ultratranslucent zirconia disks were randomly divided into 4 groups according to the surface treatment applied: airborne-particle abrasion (APA) (n=46), tribochemical silica airborne-particle abrasion (TS) (n=46), nonthermal oxygen plasma (NTP) (n=46), and no treatment, control (C) (n=31). The translucency parameter (ΔTP00) was evaluated with a spectrophotometer (n=15), phase transformation was assessed with an X-ray diffractometer (n=5), surface topography was evaluated with a scanning electron microscope (SEM) (n=3), and biaxial flexural strength (BFS) was tested with a universal testing machine (n=15). For the microshear bond strength (μSBS) test, 40 composite resin specimens were attached to 8 disks and tested with a universal testing machine; 20 specimens were tested after 24 hours, and 20 specimens after hydrothermal aging in a thermocycler (TC). The data were analyzed with ANOVA followed by the Tukey post hoc test (α=.05). Weibull analysis was performed for the flexural strength and μSBS results.

結果:

有意なΔTP00の差は全グループで認められ、APAグループで最も高く（7.33）、NTPグループで最も低かった（4.79）。NTP群は他の群に比べ、単斜晶重量分率値（4.54％）が有意に高かった。BFSは、NTP群が他の群より有意に高い値（581.31）を示し、APA群は他の群より有意に低い値（340.43）であった。APA群は24時間後（13.51MPa）、TC後（13.68MPa）のμSBS値が他の群に比べ有意に高かった（P<.05）。

RESULTS: Significant ΔTP00 differences were found among all groups and were highest for the APA group (7.33) and lowest for the NTP group (4.79). The NTP group had a significantly higher monoclinic weight fraction value (4.54%) than other groups. The NTP group had significantly higher BFS (581.31) than other groups, while the APA group showed significantly lower values than other groups (340.43). The APA group had significantly higher μSBS values after 24 hours (13.51 MPa) and after TC (13.68 MPa) than the other groups (P<.05).

結論:

APAおよびTSはレジン-ジルコニア結合を改善する有効な手法であるが，透光性および強度の劣化が著しく高い．NTPはジルコニアのBFSを有意に改善したが，他の方法より低い接着強度の値を示した．

CONCLUSIONS: Although APA and TS are effective techniques for improving resin-zirconia bonding, they result in significantly higher deterioration of translucency and strength. NTP significantly improved the BFS of zirconia; however, it showed lower bond strength values than other methods.