Holan G, Eidelman E, Wright G Z
Hebrew University, Hadassah School of Dental Medicine, Department of Pediatric Dentistry, Jerusalem, Israel.
Oper Dent. 1997 Sep-Oct;22(5):217-21.
The aim of this study was to assess the effect of intentionally leaving undermined enamel (internal bevel) along the cervical margins of class 2 composites on marginal leakage. Conventional MO and DO cavity preparations were prepared in 25 extracted permanent premolars. In each tooth the cervical margin was a butt-joint for the control group and an internal bevel for the experimental group. A transparent celluloid matrix was adapted and the teeth were restored with scotchbond Multi-Purpose and increments of Z100. A U-shaped increment was attached to the buccal and lingual walls and cervical floor of the box, leaving a gap for a middle increment. A third increment filled the occlusal part of the cavity. Following thermocycling the teeth were immersed in basic fuchsin for 24 hours, and 0.5 mm-wide sections were cut in a mesiodistal direction. Dye penetration was scored: 0 = no penetration; 1 = dye along enamel tooth interface; 2 = dye along the gingival floor; 3 = dye along pulpal wall; 4 = dye penetration into dentinal tubules. The experimental group showed 17 teeth (68%) with no dye penetration, compared to eight (32%) in the control group. Severe dye penetration (score 4) was found in only four teeth (16%) of the experimental group and 12 (48%) of the controls. The difference between the groups was statistically significant (Wilcoxon matched-pairs signed-rank test; P < 0.01). This study showed that an internal bevel at the cervical margins of class 2 composite restorations reduces marginal leakage when compared to a conventional butt-joint cavity preparation.
本研究的目的是评估在二类复合树脂修复体的颈部边缘故意保留被破坏的牙釉质（内斜面）对边缘渗漏的影响。在25颗拔除的恒牙前磨牙上制备传统的近中邻面（MO）和远中邻面（DO）窝洞。在每颗牙齿中，对照组的颈部边缘为对接接头，实验组为内斜面。适配透明赛璐珞基质，并用Scotchbond多功能粘结剂和Z100树脂分层修复牙齿。在盒状洞形的颊壁、舌壁和颈部底部附着一个U形增量，为中间增量留出间隙。第三个增量填充窝洞的咬合部分。热循环后，将牙齿浸泡在碱性品红中24小时，并沿近远中方向切割0.5毫米宽的切片。对染料渗透情况进行评分：0 = 无渗透；1 = 染料沿牙釉质-牙界面；2 = 染料沿牙龈底部；3 = 染料沿髓壁；4 = 染料渗透到牙本质小管。实验组有17颗牙齿（68%）无染料渗透，而对照组为8颗（32%）。实验组仅4颗牙齿（16%）出现严重染料渗透（评分4），对照组为12颗（48%）。两组之间的差异具有统计学意义（Wilcoxon配对符号秩检验；P < 0.01）。本研究表明，与传统的对接接头窝洞制备相比，二类复合树脂修复体颈部边缘的内斜面可减少边缘渗漏。
