Siqueira José F, Rôças Isabela N
Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, RJ 20261, Brazil.
Arch Oral Biol. 2003 Jul;48(7):495-502. doi: 10.1016/s0003-9969(03)00092-x.
Molecular genetic methods have significantly contributed to the knowledge about the microbiota associated with infected root canals. Albeit spirochetes have been commonly observed in primary root canal infections, only recently they have been identified. The purpose of the present study was to investigate the occurrence of four treponemes-Treponema maltophilum, Treponema lecithinolyticum, Treponema amylovorum, and Treponema medium-in cases of primary endodontic infections associated with different forms of periradicular diseases through a 16S rDNA-based nested PCR assay.
Samples were taken from thirty-one infected root canals associated with either asymptomatic or symptomatic apical periodontitis. DNA extracted from the samples was initially amplified using universal 16S rDNA primers, followed by a second round of amplification using the first PCR products to detect a specific fragment of the 16S rDNA of each target Treponema species.
All cases were positive for the universal bacterial primers, indicating that samples contained bacterial DNA. Of the four target species, T. maltophilum was the most prevalent, being detected in 39% of the cases (33% of the asymptomatic cases and 50% of the symptomatic cases). T. lecithinolyticum was the next more prevalent among the species tested, being found in 26% of the samples (33% of asymptomatic cases and 10% of the symptomatic cases). T. amylovorum was found in 7% of the cases (5% of the asymptomatic cases and 10% of the symptomatic cases), while T. medium was in 13% of the cases (14% of the asymptomatic cases and 10% of the symptomatic cases). None of the species tested was significantly associated with clinical symptoms.
This was possibly the hitherto first study to report the occurrence of T. lecithinolyticum, T. amylovorum, and T. medium in infections of endodontic origin. Overall, findings suggested that these oral treponemes, particularly T. maltophilum and T. lecithinolyticum, can be involved in the pathogenesis of periradicular diseases.
分子遗传学方法极大地增进了我们对与感染根管相关的微生物群的了解。尽管螺旋体在原发性根管感染中很常见，但直到最近才被鉴定出来。本研究的目的是通过基于16S rDNA的巢式PCR检测，调查在与不同形式根尖周病相关的原发性牙髓感染病例中四种密螺旋体——嗜麦芽密螺旋体、解卵磷脂密螺旋体、解淀粉密螺旋体和中间密螺旋体的出现情况。
从31个与无症状或有症状根尖周炎相关的感染根管中采集样本。从样本中提取的DNA首先使用通用16S rDNA引物进行扩增，然后使用第一轮PCR产物进行第二轮扩增，以检测每个目标密螺旋体物种16S rDNA的特定片段。
所有病例的通用细菌引物均呈阳性，表明样本中含有细菌DNA。在四种目标物种中，嗜麦芽密螺旋体最为普遍，在39%的病例中被检测到（无症状病例的33%和有症状病例的50%）。解卵磷脂密螺旋体是测试物种中第二普遍的，在26%的样本中被发现（无症状病例的33%和有症状病例的10%）。解淀粉密螺旋体在7%的病例中被发现（无症状病例的5%和有症状病例的10%），而中间密螺旋体在13%的病例中被发现（无症状病例的14%和有症状病例的10%）。所测试的物种均与临床症状无显著关联。
这可能是迄今为止第一项报告解卵磷脂密螺旋体、解淀粉密螺旋体和中间密螺旋体在牙髓源性感染中出现情况的研究。总体而言，研究结果表明这些口腔密螺旋体，尤其是嗜麦芽密螺旋体和解卵磷脂密螺旋体，可能参与根尖周病的发病机制。
