Department of Restorative Dental Science, College of Dentistry, Jazan University, Jazan, 45142, Saudi Arabia.
Department of Prosthetic Dental Science, College of Dentistry, Jazan University, Jazan, 45142, Saudi Arabia.
BMC Oral Health. 2024 Aug 21;24(1):970. doi: 10.1186/s12903-024-04755-z.
The objective of this in vitro study was to evaluate the effects of different preparation designs on the mean colour change (ΔE), marginal adaptation, fracture resistance, and fracture types of maxillary and mandibular premolar endocrowns (ECs).
A total of 40 extracted maxillary and mandibular premolars were treated endodontically, and each type was subdivided according to the remaining axial height (remaining walls on all surfaces; 2-4 mm) and 2 mm inside the pulp chamber. Specimens were immersed in coffee for 14 days, ΔE was determined, marginal adaptation was observed, fracture forces test was conducted, and the samples were examined visually at 10× magnification to evaluate failure type and identify fracture origin. The data were entered and analyzed using Statistical Package for Social Sciences, and significance between and within groups was evaluated through ANOVA. The p-value ≤ 0.05 was considered statistically significant.
The ΔE* values of the maxillary premolar with 2 mm axial height were the highest (6.8 ± 0.89 units), whereas the lowest value was observed in the mandibular premolar with 4 mm axial height (2.9 ± 0.53 units). Significant differences (p < 0.05) in teeth and design were observed. The marginal adaptation of the mandibular premolar with 4 mm axial height was the highest (30.20 ± 1.53 μm), whereas the lowest marginal adaptation was observed in the maxillary premolar with 2 mm axial height (14.38 ± 0.99 μm), and the difference was statistically significant (p < 0.05). The maximum fracture force was observed in maxillary premolars with 2 mm axial height (2248.15 ± 134.74 N), and no statistically significant difference (p = 0.07) was observed between maxillary and mandibular premolars at 4 mm axial height.
The recorded ΔE values of the ECs were within clinically acceptable values or slightly higher, and the marginal adaption values were within acceptable and recommended clinical values in µm. EC preparation with 2 mm axial height in both arches recorded the highest fracture forces. Type III (split fracture) failure was recorded as the highest in the maxillary and mandibular premolar ECs with different axial wall heights.
本体外研究旨在评估不同预备设计对上颌和下颌前磨牙嵌体冠（EC）的平均颜色变化（ΔE）、边缘适合性、抗折强度和骨折类型的影响。
共处理 40 颗上颌和下颌前磨牙的牙髓，并根据剩余轴向高度（所有表面的剩余壁；2-4mm）和牙髓腔内部的 2mm 将每种类型进一步细分。将标本浸入咖啡中 14 天，测定 ΔE，观察边缘适合性，进行抗折强度测试，并在 10×放大倍数下目视检查样品，以评估失效类型并确定骨折起源。使用社会科学统计软件包输入和分析数据，并通过方差分析评估组间和组内的显著性。p 值≤0.05 被认为具有统计学意义。
2mm 轴向高度的上颌前磨牙的 ΔE*值最高（6.8±0.89 单位），而 4mm 轴向高度的下颌前磨牙的最低值（2.9±0.53 单位）。牙齿和设计之间存在显著差异（p<0.05）。4mm 轴向高度的下颌前磨牙的边缘适合性最高（30.20±1.53μm），而 2mm 轴向高度的上颌前磨牙的最低边缘适合性（14.38±0.99μm），差异具有统计学意义（p<0.05）。2mm 轴向高度的上颌前磨牙的最大骨折力最高（2248.15±134.74N），4mm 轴向高度的上颌和下颌前磨牙之间无统计学显著差异（p=0.07）。
EC 的记录 ΔE 值在临床可接受范围内或略高，边缘适应值在 µm 内处于可接受和推荐的临床值范围内。上颌和下颌的 2mm 轴向高度的 EC 预备记录了最高的骨折力。在上颌和下颌前磨牙 EC 中，记录到的 III 型（劈裂骨折）失效最高。
