合着用レジン添加型グラスアイオノマーセメントの熱機械特性が修復物の保持性に及ぼす効果

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This study investigated the effect of termo-mechanical properties on the retention durability of restorations using resin-modified glass-ionomer cements for luting after thermal-cycling tests (TC-test, 10,000, 30,000, 50,000 cycles) on films of various thickness (50, 100, 200μm). Two types of resin-modified glass-ionomer cements were used in this study, Fuji Lute (GC, RG1) and Vitremer luting cement (3M, RG2), and zinc phosphate cement (Elite cement 100(GC, ZPC)), glass-ionomer cement(Fuji 1, GC, GIC) and resin cement (Bistite resin cement (RC), Tokuyama) were used as controls. The bond strength, thermal expansion coefficient, elasticmodulus and filler components of cements were measured in this experiment. The durability evaluated by failure frequency of bonding specimens and magnitude of theoretical thermal stress at the adhesive interface was calculated numerically. The findings were as follows. 1. The elastic modulus decreased slightly with all cements after 24-hour setting compared with that after the TC-test (10,000 cycles), but a significant decrease was indicated in RC only. 2. The mean thermal expansion coefficient of the cements in the range from 5 to 55℃ after 24-hour setting was compared with that after the TC-test (10,000 cycles), and only RG1 indicated a significant decrease. However, the thermal expansion coefficient in a narrow thermal range showed a significant increase in ZPC at 10, 37 and 55℃, and in GIC and 37 and 55℃. However, a significant decrease was found only in RG1 at 37 and 55℃, and RG2 at 55℃; it is considered that this phenomenon indicates softening for RG1 and RG2 between 37 and 55℃. 3. The mean thermal stress for each cement in the range from 5 to 55℃ was calculated at the adhesive interface of cement-dentin (C/D) and alloy-cement (A/C). It was higher at C/D than A/C in ZPC and GIC, but it was higher at A/C than C/D in RG1, RG2 and RC. The thermal stress of the cements after 24-hour setting was compared with that after the TC-test (10,000 cycles). The stress of RG1 showed the largest decrease among these cements; at C/D, the value was 0.75 (MPa, 22.9%) and at A/C 0.02 (MPa, 0.8%) after the TC-test. For RG2, the stress decreased to 1.11 (84.7%) and 0.55 (88.7%), and that of RC was 2.52 (73.3%) and 1.55 (64.6%) at C/D and A/C, respectively. 4. Regarding the thermal stress of RG1, RG2 and RC relative to the filler components after 24-hour setting, the stress of RC was the largest; that of RG1 was larger than that of RG2. However, the stress of RG1 was calculated to be the smallest after the TC-test (10,000 cycles). 5. Regarding the frequency of failure of bonding test specimens, the specimens of RG1 did not fail after the TC-test (50,000 cycles) on the films of 3 thicknesses, indication that RG1 has excellent retention durability. However, RC showed the highest bonding strength of all cements tested. These findings indicate that the visco-elastic property of resin-modified glass-ionomer cement allowed effective relaxation during thermal stress as well as good retention durability of restorations.
特定非営利活動法人日本歯科保存学会の論文
2006-12-31

合着用レジン添加型グラスアイオノマーセメントの熱機械特性が修復物の保持性に及ぼす効果

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