Christie W H, Thompson G K
Faculty of Dentistry, University of Manitoba, Winnipeg.
J Can Dent Assoc. 1994 Jun;60(6):527-32, 535-6.
The principle of straight-line access is discussed with particular reference to endodontic access of either maxillary or mandibular molar teeth. Modifications to the traditional triangular access opening are described that will make it easier for a practitioner to locate and instrument the fourth canal system commonly found in molar teeth. The high frequency of a fourth canal in molar teeth makes it essential to anticipate and find all canals during molar endodontic therapy. Quite frequently, the general practitioner attempting molar endodontic therapy should expect to locate a second canal in the mesiobuccal root of the maxillary molar and a second canal in the distal root of a mandibular molar. The possibility of extra roots over and above the norm should also be anticipated and looked for carefully. Proper angulation and interpretation of radiographs help to identify chamber and root anatomy. A two-step access opening is advocated when making access openings on molar teeth if a coronal crack in the crown is to be seen early in treatment. A method of unroofing the pulp chamber and pre-flaring the canal orifice to facilitate the subsequent shaping of the entire root-canal system is described. Clinical and laboratory examples are pictured to illustrate modifications or errors in the standard endodontic access opening.
本文特别参照上颌或下颌磨牙的根管治疗入口，讨论了直线进入原则。文中描述了对传统三角形入口开口的改进方法，这将使从业者更容易定位和处理磨牙中常见的第四根管系统。磨牙中第四根管的高发生率使得在磨牙根管治疗期间预测并找到所有根管至关重要。通常，进行磨牙根管治疗的全科医生应预期在上颌磨牙的近中颊根中找到第二根管，并在下颌磨牙的远中根中找到第二根管。还应预期并仔细查找超出正常数量的额外牙根的可能性。正确的角度和对X光片的解读有助于识别髓腔和牙根解剖结构。如果要在治疗早期发现牙冠的冠部裂纹，在磨牙上制作入口开口时提倡采用两步法入口开口。本文描述了一种打开髓腔并预先扩大根管口以促进后续整个根管系统塑形的方法。文中展示了临床和实验室示例，以说明标准根管治疗入口开口中的改进或错误。
