Mitchell C A, Pintado M R, Douglas W H
School of Clinical Dentistry, The Queen's University of Belfast, Belfast, Northern Ireland, United Kingdom.
J Prosthet Dent. 2001 Jun;85(6):575-84. doi: 10.1067/mpr.2001.114268.
It is important that artificial crowns fit the prepared tooth accurately, as marginal deficiencies are predisposed to plaque accumulation and lead to increased risk of periodontal disease. Various methods of evaluation for marginal fit are described in the literature, but most approaches are limited by destructive methods of assessment and/or small points of measurement.
This study compared, in vitro, the marginal fit of 4 types of complete crowns on human premolar teeth with the use of nondestructive profilometry. This method determined whether fit was influenced by type of crown or surface morphology of the tooth, namely, grooved or ungrooved surfaces.
Four groups of specimens were prepared for complete crowns: group BA, bonding alloy with chamfer finish line; group G, gold alloy with chamfer finish line; group PC, porcelain with a chamfer finish line; and group PS, porcelain with a shoulder finish line. Two profiles of grooved mesial and ungrooved distal surfaces of the teeth were performed: (1) teeth prepared for each type of crown and (2) teeth with crowns seated but not cemented. Marginal fit (absolute marginal discrepancy) from the finish line edge of the tooth preparations to crown edges (CE) and leading edges (LE) of crowns were measured.
A 2-way analysis of variance for crown type and tooth surface morphology revealed significant differences between crown types for all measurement parameters, except vertical LE. The effect of surface morphology was not significant, except for vertical LE (P<.05). For all parameters, except vertical LE, the ranking of marginal fit discrepancies from greatest to least was as follows: group PC, G, BA, and PS. For vertical LE distances, the ranking was PS, BA, G, and PC (P<.05).
Profilometry was used as a nondestructive, accurate method of evaluating the absolute marginal fit of different types of crowns. Marginal fits varied continuously around the circumference of each crown and made clinical assessment of fit accuracy subjective and arduous.
人造牙冠精确适配预备好的牙齿非常重要，因为边缘缺陷易导致菌斑积聚，并增加患牙周疾病的风险。文献中描述了多种边缘适配性的评估方法，但大多数方法受到破坏性评估方法和/或测量点较少的限制。
本研究在体外使用无损轮廓测量法比较了4种类型全冠在人前磨牙上的边缘适配性。该方法确定了适配性是否受牙冠类型或牙齿表面形态（即有沟或无沟表面）的影响。
制备了四组全冠标本：BA组，带倒角边缘线的粘结合金冠；G组，带倒角边缘线的金合金冠；PC组，带倒角边缘线的瓷冠；PS组，带肩台边缘线的瓷冠。对牙齿有沟的近中面和无沟的远中面进行了两种轮廓测量：(1)为每种类型牙冠预备的牙齿；(2)已就位但未粘结的带冠牙齿。测量从牙齿预备体的边缘线边缘到牙冠边缘（CE）和牙冠前缘（LE）的边缘适配性（绝对边缘差异）。
对牙冠类型和牙齿表面形态进行的双向方差分析显示，除垂直LE外，所有测量参数在牙冠类型之间均存在显著差异。表面形态的影响不显著，垂直LE除外（P<0.05）。对于所有参数，除垂直LE外，边缘适配差异从大到小的排序如下：PC组、G组、BA组和PS组。对于垂直LE距离，排序为PS组、BA组、G组和PC组（P<0.05）。
轮廓测量法被用作评估不同类型牙冠绝对边缘适配性的一种无损、准确的方法。边缘适配性在每个牙冠的圆周上连续变化，使得对适配准确性的临床评估主观且艰巨。
