Progress of LPS-induced apical lesion in rat immature mandibular molars
Progress of LPS-induced apical lesion in rat immature mandibular molars
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DOI：
10.1016/j.pdj.2022.12.001
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发表时间：
2023-01
影响因子：
0.8
通讯作者：
Chikako Nakajima;Maiko Fujita-Otani;Y. Mikuni‐Takagaki;Kuniomi Nakamura;Kouki Hidaka;A. Kawata;Ryota Kawamata;S. Kimoto
中科院分区：
文献类型：
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作者：
Chikako Nakajima;Maiko Fujita-Otani;Y. Mikuni‐Takagaki;Kuniomi Nakamura;Kouki Hidaka;A. Kawata;Ryota Kawamata;S. Kimoto
在日常实践中，牙医经常被要求对未成熟的恒牙进行牙髓治疗，例如中央结节断裂的牙齿。未成熟恒牙的牙根通常是不完整的，根尖呈漏斗状，治疗困难。中央结节是一种异常形式的牙冠，主要出现在前磨牙咬合面的中心部分，更常见于蒙古人。据报道，约有1%的日本人[1]会发生牙周炎，且多见于下颌第二前磨牙[1 e4]。骨折通常发生在牙齿萌出的过程中，因此有必要注意防止通过骨折裂缝感染牙髓[5]。目前，还没有达成共识的标准治疗方法来帮助根发育完成这一过程。这是一个迫切的任务，以建立一个可靠的方案，导致正常的恒牙与成熟的牙根。对这类未成熟牙齿进行根管治疗的目的是尽可能地保留它们的功能。动物模型已经被用于评估某些发病机制，识别新药的作用，并在临床试验之前确定干预的结果。到目前为止，牙科实验经常使用大鼠上颌磨牙[6 E8]，而不是下颌骨，因为与大鼠下颌骨相关的面颊、舌头和颅周组织存在解剖学上的限制。虽然使用下颌牙齿的研究很少，但某些临床情况，如中央结节骨折，需要使用下颌牙齿模型。在龋齿、创伤或其他疾病期间，根尖周组织的感染可能是由于微生物侵入牙髓而引起的。根尖周围组织的炎症反应是由根管系统中的微生物感染引起的[9]。由此导致的根尖周炎是一种以牙周组织和牙槽骨减少为特征的炎症性疾病。通过手术暴露牙髓制备的根尖周炎模型已被广泛使用，主要用于大鼠，其牙髓处于开放状态并暴露在口腔细菌中。感染的牙髓组织随后被用作牙周炎模型[10，11]。在这样的模型中，很难确定发生在根尖的感染的来源和程度。另一方面，通过将病原体直接注射到牙髓中并用玻璃离子粘固剂封闭它，可以控制病原体的来源并确定诱导炎症的程度，然后进行愈合，从而获得根尖周炎模型。然而，在幼年大鼠的下颌牙齿上进行这样的手术是具有挑战性的。在本研究中，我们开发了一种便于对大鼠下颌磨牙进行操作的装置，该装置可用于建立下颌牙模型。利用这一新型手术床，我们观察了牙龈卟啉单胞菌脂多糖(PG-LPS)在下颌第一磨牙牙髓内注射的效果。在接种后1周(PG-1w)和2周(PG-2w)通过显微CT成像、抗体阵列、碱性磷酸酶(ALP)和TRACP-5b活性染色以及免疫荧光染色来评估疗效。我们获得了有关炎症导致愈合过程的有用信息，这可能有助于开发新的治疗方法。
In daily practice, dentists are often required to perform endodontic treatment in immature permanent teeth such as those with a fractured central tubercle. The roots of immature permanent teeth are usually incomplete with a funnel-shaped apex making treatment difficult. A central tubercle is an abnormal form of crown that appears mainly on the central portion of the occlusal surface of premolars, more commonly in mongoloids. It has been reported to form in about 1% of Japanese [1] and to be found mostly in mandibular second premolars [1 e4]. Fractures generally occur during the process of tooth eruption necessitating attention to prevent dental pulp infection through fracture cracks [5]. Currently, there is no agreed standard treatment to aid root development to complete the process. This is an urgent task to establish a reliable protocol leading to normal permanent teeth with mature roots. The goal of endodontic treatment of such immature teeth is to preserve their function as much as possible. Animal models have been used in evaluating certain pathogenesis, identifying the actions of novel drugs, and determining the results of interventions prior to clinical trials. To date, dental experiments have often used rat maxillary molars [6 e8] rather than mandibles because of anatomical constraints with cheek, tongue, and pericranial tissues associated with rat mandible. While few studies used mandibular teeth, certain clinical conditions such as central tubercle fracture necessitate use of mandibular teeth models. Infection of periapical tissues may occur by pathogenic invasion of microorganisms into the dental pulp during dental caries, trauma or other ailments. Inflammatory reaction in periapical tissues is induced by microbial infection in the root canal system [9]. Resulting root apex periodontitis is an inflammatory disease characterized by reduced periodontal tissue and alveolar bone. Apical periodontitis models prepared by surgically exposing dental pulp have been widely used, mostly with rats whose dental pulp was left open and exposed to oral bacteria. Infected pulpal tissue was then used as a periodontitis model [10, 11]. It is difficult to identify the source and extent of an infection occurred at the root apex in such a model. On the other hand, by injecting a pathogen directly into the dental pulp and sealing it with glass ionomer cement, one can control the source and determine the extent of induced inflammation followed by healing to obtain an apical periodontitis model. To perform such an operation on mandibular teeth of young rats, is challenging, however. In the present study, we developed apparatus, a table, to facilitate easy operation on rat mandibular molars which may be used to develop mandibular teeth models. Using this novel operation table, we examined the effect of Porphyromonas gingivalis lipopolysaccharide (Pg LPS) injected into the pulp of mandibular first molar teeth. The effects were assessed at 1-week (Pg-1w) and 2-weeks (Pg-2w) post-inoculation by micro CT imaging, antibody array, activity staining for ALP and TRACP-5b and immunofluorescence staining. We obtained useful information with regard to the process of inflammation leading to healing that could contribute to the development of new treatment methods.