Division of Operative Dentistry, Department of Restorative and Biomaterials Sciences, Meikai University School of Dentistry, Sakado, Saitama 350-0283, Japan.
In Vivo. 2011 Jan-Feb;25(1):93-8.
Many drugs (including toxicants) and radiation therapy have been reported to exert bi-phasic hormetic effects on cultured cells, but only when both the concentration and treatment time were optimal. Most previous studies have been carried out with multiple laser modalities other than CO(2) laser, and there has been no comparison of the hormetic response between normal and tumor cells. We investigated here whether CO(2) laser treatment induces hormesis in human gingival fibroblast (HGF) and oral squamous cell carcinoma (HSC-2) cells.
Cells were cultured for 24, 48 or 72 hours after exposure to various irradiation powers, and the viable cell number was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method.
CO(2) laser irradiation stimulated cell growth at low and inhibited it at high irradiation power. Among three dispatch modes, super pulse (SP)2 most effectively induced growth stimulation in HGF, at an irradiation dose slightly lower than that which induced cytotoxicity. Higher irradiation doses were comparably cytotoxic against both normal (HGF) and tumor (HSC-2) cells, reaching a plateau of cytotoxicity within 24 hours.
Since both the range and magnitude of hormetic response in HGF cells were very narrow and small, it is crucial to establish the optimal conditions for hormesis induction for clinical application in dentistry.
许多药物（包括毒素）和放射疗法已被报道对培养细胞产生双相激动效应，但仅在浓度和处理时间最佳时才会产生。大多数先前的研究都是使用 CO2 激光以外的多种激光模式进行的，并且没有比较正常细胞和肿瘤细胞之间的激动反应。我们在此研究 CO2 激光处理是否会引起人牙龈成纤维细胞（HGF）和口腔鳞状细胞癌（HSC-2）细胞的激动反应。
将细胞暴露于不同的辐照功率下 24、48 或 72 小时后进行培养，并通过 3-（4,5-二甲基噻唑-2-基）-2,5-二苯基四氮唑溴化物（MTT）法测定活细胞数。
CO2 激光辐照在低剂量下刺激细胞生长，在高剂量下抑制细胞生长。在三种发射模式中，超脉冲（SP）2 最有效地刺激 HGF 细胞生长，辐照剂量略低于诱导细胞毒性的剂量。更高的辐照剂量对正常（HGF）和肿瘤（HSC-2）细胞的细胞毒性相当，在 24 小时内达到细胞毒性平台。
由于 HGF 细胞中的激动反应范围和幅度都非常狭窄和小，因此对于在牙科临床应用中诱导激动反应，建立最佳条件至关重要。
