Abstract：
Theoretically, a necrotic root canal fulfils all requirements as a niche for methanogens to inhabit. However, their presence in it and its implication in apical periodontitis (AP) is controversial. Therefore, to contribute to ending the controversy, this study aimed to detect and compare methanogens\' presence in two distinct niches with supposedly different microenvironments; both were necrotic root canals associated with AP but one from patients with type 2 diabetes mellitus (T2DM) while the other from non-diabetic patients. A clinical examination was performed on 65 T2DM patients and 73 non-diabetic controls. Samples from necrotic root canals were obtained, and methanogens were identified. The presence of methanogens was three times higher (27.6%) in the T2DM group than in non-diabetic patients (8.2%). In addition, methanogens\' presence was associated with a higher prevalence of periapical symptoms.
摘要：
理论上,作为产甲烷菌栖息的生态位，坏死根管满足所有要求。然而,它们在其中的存在及其在根尖周炎（AP）中的意义是有争议的。因此,为了结束这场争论，这项研究旨在检测和比较产甲烷菌存在于两个具有不同微环境的不同生态位中;两者都是与AP相关的坏死根管,但一个来自2型糖尿病(T2DM)患者,另一个来自非糖尿病患者.对65名T2DM患者和73名非糖尿病对照进行了临床检查。从坏死根管获得样品，并鉴定了产甲烷菌。T2DM组产甲烷菌的存在是非糖尿病患者（8.2％）的三倍（27.6％）。此外,产甲烷菌的存在与根尖周症状的患病率较高相关。
