de Souza Pedro Paulo Chaves, Hebling Josimeri, Scalon Mariana Grecco, Aranha Andreza Maria Fábio, Costa Carlos Alberto de Souza
Department of Biochemistry and Immunology, Faculty of Medicine, University of São Paulo, USP, São Paulo, Brazil.
Am J Dent. 2009 Jun;22(3):151-6.
To investigate the effects of intrapulpal temperature changes induced by a quartz tungsten halogen (QTH) and a light emitting diode (LED) curing units on the metabolism of odontoblast-like cells.
Thirty-six 0.5 mm-thick dentin discs obtained from sound human teeth were randomly assigned into three groups: QTH, LED and no light (control). After placement of the dentin discs in pulp chamber devices, a thermistor was attached to the pulpal surface of each disc and the light sources were applied on the occlusal surface. After registering the temperature change, odontoblast-like cells MDPC-23 were seeded on the pulpal side of the discs and the curing lights were again applied. Cell metabolism was evaluated by the MTT assay and cell morphology was assessed by SEM.
In groups QTH and LED the intrapulpal temperature increased by 6.4 degrees C and 3.4 degrees C, respectively. The difference between both groups was statistically significant (Mann-Whitney; P < 0.05). QTH and LED reduced the cell metabolism by 36.4% and 33.4%, respectively. Regarding the cell metabolism, no statistically significant difference was observed between both groups (Mann-Whitney; P > 0.05). However, when compared to the control, only QTH significantly reduced the cell metabolism (Mann-Whitney; P < 0.05). It was concluded that the irradiance of 0.5 mm-thick human dentin discs with a QTH in comparison to a LED curing unit promoted a higher temperature rise, which propagates through the dentin negatively affecting the metabolism of the underlying cultured pulp cells.
研究石英钨卤素（QTH）和发光二极管（LED）固化灯引起的牙髓腔内温度变化对成牙本质细胞样细胞代谢的影响。
从健康人牙齿获取36个0.5毫米厚的牙本质圆盘，随机分为三组：QTH组、LED组和无光照组（对照组）。将牙本质圆盘置于牙髓腔装置中后，在每个圆盘的牙髓表面连接一个热敏电阻，并在咬合面施加光源。记录温度变化后，将成牙本质细胞样细胞MDPC - 23接种在圆盘的牙髓侧，并再次施加固化光。通过MTT法评估细胞代谢，通过扫描电子显微镜评估细胞形态。
QTH组和LED组牙髓腔内温度分别升高了6.4摄氏度和3.4摄氏度。两组之间的差异具有统计学意义（曼 - 惠特尼检验；P < 0.05）。QTH组和LED组分别使细胞代谢降低了36.4%和33.4%。关于细胞代谢，两组之间未观察到统计学显著差异（曼 - 惠特尼检验；P > 0.05）。然而，与对照组相比，只有QTH组显著降低了细胞代谢（曼 - 惠特尼检验；P < 0.05）。得出的结论是，与LED固化灯相比，用QTH照射0.5毫米厚的人牙本质圆盘会导致更高的温度升高，该温度通过牙本质传播，对下层培养的牙髓细胞的代谢产生负面影响。
