Camoes Izabel C G, Salles Milton R, Fernando Mourao Vieira M, Freitas Lilian F, Gomes Cinthya C
Department of Clinical Dentistry, Center of Medical Sciences, Fluminense Federal University, Niterói, RJ, Brazil.
Indian J Dent Res. 2009 Oct-Dec;20(4):426-30. doi: 10.4103/0970-9290.59443.
Sodium hypochlorite (NaOCl) is the most widely used endodontic irrigant because of its excellent antimicrobial, organic tissue dissolving, and lubricating properties. However, it is highly cytotoxic to the periapical tissues.
This study evaluated in vitro the extrusion of 5.25% NaOCl through the apical foramina of mesiobuccal (MB) root canals of maxillary first molars in two experimental conditions: Before apical debridement and after apical debridement with different instrument sizes to ensure direct access to the apical foramen (apical patency).
Coronal accesses were prepared in 17 teeth and the apical foramina of the distobuccal and palatal root canals were sealed. The teeth were held in acrylic receptacles with the roots turned upwards to reproduce their position in the maxillary dental arch. The receptacles were filled with a starch/KI solution (a reagent that changes its color to blue after contacting NaOCl) covering the roots. The experiment had two phases: P1: Irrigation of the MB canals with 5.25% NaOCl without previous establishment of apical patency; P2: Canal irrigation after use of size 10 K-file and size 15 Flexofile as patency files. Only specimens with no NaOCl extrusion in P1 were assigned to P2. NaOCl was delivered pressureless at the canal entrance. The moment that the starch/KI solution contacted NaOCl was captured on digital photographs.
There was no NaOCl extrusion in nine specimens in P1, but all of these teeth had irrigant extrusion in P2. The 5.25% NaOCl used as an endodontic irrigant showed great capacity to extrude beyond both intact and small-sized apical foramina of MB root canals of maxillary first molars.
次氯酸钠（NaOCl）因其出色的抗菌、溶解有机组织和润滑特性，是最广泛使用的根管冲洗剂。然而，它对根尖周组织具有高度细胞毒性。
本研究在两种实验条件下，体外评估5.25% NaOCl通过上颌第一磨牙近中颊（MB）根管根尖孔的挤出情况：根尖清创术前以及使用不同器械尺寸进行根尖清创以确保直接通达根尖孔（根尖通畅）后。
对17颗牙齿制备冠部通道，并封闭远中颊和腭根管的根尖孔。将牙齿固定在丙烯酸容器中，牙根向上以重现其在上颌牙弓中的位置。容器中填充淀粉/KI溶液（一种与NaOCl接触后会变为蓝色的试剂）覆盖牙根。实验分为两个阶段：P1：在未预先建立根尖通畅的情况下，用5.25% NaOCl冲洗MB根管；P2：使用10号K锉和15号Flexofile作为通畅锉后进行根管冲洗。仅将在P1中无NaOCl挤出的标本分配到P2。NaOCl在根管入口处无压力输送。淀粉/KI溶液与NaOCl接触的瞬间通过数码照片记录。
在P1中，9个标本没有NaOCl挤出，但所有这些牙齿在P2中都有冲洗剂挤出。用作根管冲洗剂的5.25% NaOCl显示出有很大能力挤出上颌第一磨牙MB根管完整和小尺寸根尖孔之外。
