微波和水浴聚合方法对热固化聚甲基丙烯酸甲酯树脂基托义齿精度和抗弯强度的影响

目的:观察微波和水浴聚合方法对热固化聚甲基丙烯酸甲酯树脂基托义齿精度和抗弯强度的影响.方法:采用402 U标准上颌无牙台原模以及标准上颌全曰义齿原模制作10副上颌全口义齿,随机数字表法分成微波聚合法组和水浴聚合法组,每组5个.微波聚合法在40%的火力下加热9 min,自然冷却至室温,开盒,严格控制装盒压力大小为4.5 kg/mm~2;水浴聚合法由室温升温到70℃,恒温1.5 h,再升温到100℃,恒温0.5 h,自然冷却至室温,开盒.义齿在25℃恒温水浴中保存1周,在上颌第2磨牙远中部位切断义齿基托与标准模型,用数字显微镜测量上颌全口义齿基托组织面与标准模型之间共5个部位的间隙.分别用上述两种聚合方法制作64 mm×10 mm×2.5 mm的树脂基托试样,采用电子万能试验机测量其抗弯强度.结果:微波法和水浴法制作的义齿在相同点处间隙大小差异无显著性意义(141±78),(147±74)μm,P＞0.05].微波法和水浴法制作试样的抗弯强度差异无显著性意义(81.60±14.04),(84.24±17.65)MPa,P＞0.05].结论:微波聚合法和水浴聚合法制作的义齿精度和抗弯强度无明显差别,但微波法聚合时间较水浴法大为缩短.

Effects of microwave polymerization and water-bath heat polymerization on accuracy and flexural strength of denture base resin

OBJECTIVE: To evaluate the effect of microwave polymerization and water-bath heat polymerization on accuracy and flexural strength of denture base resin. METHODS: Ten maxillary complete dentures were prepared and divided into microwave polymerization and water-bath heat polymerization groups according to random number table, with 5 dentures in each group. In the microwave polymerization group, the dentures were heated for 9 minutes with 40% firepower, natural cooled, the pressure of flasking at 4.5 kg/mm~2. In the water-bath heat polymerization group, the temperature increased from room to 70℃, sustained for 1.5 hours, then rise to 100℃ for 0.5 hour. The dentures were maintained at 25℃ thermostatic water bath for a week. The denture base, as well as standard cast was cut down at posterior border of the second molar. Dimensional accuracy between the posterior border of upper complete denture and standardized cast at five different positions was measured by digital microscope. Specimens with 64 mm× 10 mm×2.5 mm were made for measuring flexural strength.RESULTS: ①The posterior border gaps between the upper complete denture and standardized cast was (141±78) urn and (147±74) μm cured by microwave polymerization and water-bath heat polymerization, which has no statistical difference. The flexural strength of denture base resin cured by the microwave polymerization and water-bath heat polymerization was (81.60±14.04) MPa and (84.24±17.65) MPa, and there was no statistical difference (P > 0.05). CONCLUSION: There is no significantly difference in the accuracy and flexural strength cured by microwave polymerization and by water-bath heat polymerization, but the microwave polymerization takes shorter time than that by water-bath heat polymerization.