Ibrahim Amal Mamdouh B R, Richards Lindsay C, Berekally Thomas L
Lecturer, Department of Conservative Dentistry, School of Dentistry, University of Adelaide, SA, Australia.
Professor, School of Dentistry, University of Adelaide, SA, Australia.
J Prosthet Dent. 2016 Mar;115(3):290-5. doi: 10.1016/j.prosdent.2015.08.013. Epub 2015 Nov 6.
Assessing the quantity and distribution of residual coronal dentin is important in deciding the restorability of endodontically treated teeth.
The purpose of this in vitro study was to investigate the relationship between the cross-sectional area and location of remaining coronal tooth structure and the fracture resistance of restored teeth after endodontic treatment.
Fifty-five extracted maxillary premolars received endodontic treatment and crown preparations. The teeth were assigned to 11 groups of 5 teeth according to the number and the location of missing axial walls. Impressions of the prepared teeth were made to fabricate dies. Each die was sectioned 1 mm above the finish line, and the dentin surface area was measured. All teeth were restored with composite resin cores and cast metal crowns. The specimens were thermocycled between 5°C and 55°C for 500 cycles before loading until failure with a universal testing machine. The results were analyzed with 1-way ANOVA and post hoc comparisons.
Specimens with all axial walls intact around the access cavity had the highest mean fracture strength (1380.5 ±393.9 N). Groups with the palatal and 1 or 2 proximal walls missing showed the lowest mean failure loads (398.4 N ±149.5 N and 344.7 N ±91.2 N). The correlation between the surface area and the fracture resistance was 0.72 CONCLUSIONS: For restored endodontically treated maxillary premolars, a positive linear relationship was found between the remaining coronal dentin surface area and fracture strength. Residual dentin location influences fracture resistance.
评估剩余牙冠牙本质的数量和分布对于确定经牙髓治疗牙齿的可修复性很重要。
本体外研究的目的是调查剩余牙冠结构的横截面积和位置与牙髓治疗后修复牙齿的抗折性之间的关系。
55颗拔除的上颌前磨牙接受了牙髓治疗和牙冠预备。根据缺失轴向壁的数量和位置，将牙齿分为11组，每组5颗。对预备好的牙齿制取印模以制作代型。每个代型在完成线以上1mm处进行切片，并测量牙本质表面积。所有牙齿均用复合树脂核和铸造金属冠修复。在万能试验机上加载直至破坏之前，将标本在5°C至55°C之间进行500次热循环。结果采用单因素方差分析和事后比较进行分析。
在进入腔周围所有轴向壁均完整的标本具有最高的平均抗折强度（1380.5±393.9N）。腭侧和1个或2个近中壁缺失的组显示出最低的平均破坏载荷（398.4N±149.5N和344.7N±91.2N）。表面积与抗折性之间的相关性为0.72。
对于经牙髓治疗后修复的上颌前磨牙，发现剩余牙冠牙本质表面积与抗折强度之间存在正线性关系。剩余牙本质的位置影响抗折性。
