Department of Dental Materials and Prosthodontics, Araraquara Dental School, UNESP - Univ. Estadual Paulista, Araraquara, SP, Brazil.
Caries Res. 2010;44(4):349-57. doi: 10.1159/000318528. Epub 2010 Jul 10.
Enamel specimens need to be disinfected before being used in intraoral appliances and the disinfection method must not affect the integrity of the tooth. This study evaluated the effectiveness of microwave bovine enamel disinfection and its effect on the surface microhardness (SMH) and cross-sectional microhardness (CSMH) of sound, demineralized and remineralized enamel. Forty enamel specimens were divided into two groups (n = 20): control (nonirradiated) and microwave. Microwave specimens were immersed in water and irradiated (650 W/3 min). Specimens were incubated at 37 degrees C for 7 days under aerobic and anaerobic conditions. An aliquot was removed for counting, plated at serial dilutions on blood agar plates, which were incubated aerobically and anaerobically. The colony-forming units were calculated. Other 20 enamel specimens (4 x 4 mm) were embedded in acrylic resin, polished and sliced into two halves: one of the fragments was reserved as control while the other was microwaved. SMH and CSMH of sound enamel were analyzed for both groups. The CSMH was further evaluated after demineralization and remineralization cycles. The Knoop integral (DeltaKI) was also calculated. Data were analyzed statistically by paired Student's t test (alpha = 0.05). While control specimens showed microbial growth, those microwaved were disinfected. There were no significant differences in SMH, CSMH and DeltaKI between the control and microwave groups. Microwave irradiation for 3 min at 650 W was effective for the complete disinfection of bovine enamel specimens without affecting the SMH and CSMH of sound, demineralized and remineralized enamel.
釉质标本在用于口腔内器械之前需要消毒，消毒方法不能影响牙齿的完整性。本研究评估了微波牛釉质消毒的有效性及其对健康、脱矿和再矿化釉质表面显微硬度（SMH）和横截面显微硬度（CSMH）的影响。将 40 个釉质标本分为两组（n=20）：对照组（未辐照）和微波组。将微波标本浸入水中并辐照（650 W/3 分钟）。标本在 37°C 下孵育 7 天，在有氧和厌氧条件下。取出一部分进行计数，在血琼脂平板上进行连续稀释平板接种，在有氧和厌氧条件下孵育。计算菌落形成单位。另外 20 个釉质标本（4x4mm）嵌入丙烯酸树脂中，抛光并切成两半：一半作为对照保留，另一半用微波处理。分析两组健康釉质的 SMH 和 CSMH。在脱矿和再矿化循环后进一步评估 CSMH。还计算了克努普积分（DeltaKI）。通过配对学生 t 检验（alpha=0.05）对数据进行统计学分析。虽然对照组标本显示有微生物生长，但经微波处理的标本已消毒。对照组和微波组之间的 SMH、CSMH 和 DeltaKI 没有显著差异。在 650 W 下辐照 3 分钟的微波照射对牛釉质标本的完全消毒有效，而不会影响健康、脱矿和再矿化釉质的 SMH 和 CSMH。
