Statement of problem

The clinical success of monolithic lithium disilicate glass-ceramic (LDGC) crowns manufactured with computer-aided design and computer-aided manufacturing (CAD-CAM) technology provided by predoctoral students has not been fully investigated.

Purpose

The purpose of this retrospective clinical study was to evaluate the performance of laboratory-fabricated monolithic posterior LDGC CAD-CAM crowns provided by predoctoral students at the University of Toronto. Specific patient- and provider-related factors were also investigated.

Material and methods

A sample of posterior LDGC CAD-CAM crowns (IPS e.max) provided by predoctoral students was evaluated. Crown preparations were made according to specific criteria, and crowns were milled in an in-house laboratory by using the CEREC Bluecam system. The crowns were cemented with Rely-X Unicem (3M ESPE) and Calibra Universal (Dentsply Sirona) resin cements. Clinical assessments of the crowns and supporting periodontal structures were performed following the modified California Dental Association (CDA) criteria. Intraoral photographs and periapical and bitewing radiographs were obtained for further assessment by 2 evaluators. Descriptive statistics, McNemar, t test, log rank (Mantel-Cox) tests, Pearson chi-squared tests, simple logistic regression, odds ratios, and Kaplan Meier survival analyses were performed (α=.05).

Results

A total of 189 patients receiving 210 crowns (108 premolar and 102 molar) were examined with a follow-up period of up to 6 years. Altogether, 28 complications were observed (12 technical, 11 biological, and 5 esthetic). No significant association was found between patient age, sex, periodontal condition, tooth type, tooth vitality, cement type, and crown longevity. However, significantly lower survival and success rates were found for mandibular crowns than for maxillary crowns (P=.029). The provider’s experience had no significant effect on the clinical performance of LDGC CAD-CAM crowns. The 6-year cumulative survival rate was 93.0%, and the success rate was 86.4%.

Conclusions

The ease of use of the CAD-CAM system and clinical performance of LDGC suggest that this technology should be used in the dental school setting by predoctoral students.

中文翻译：

---

多伦多大学博士前学生提供的 CAD-CAM 牙冠临床表现

问题陈述

由博士前学生提供的计算机辅助设计和计算机辅助制造 (CAD-CAM) 技术制造的单片二硅酸锂玻璃陶瓷 (LDGC) 冠的临床成功尚未得到充分研究。

目的

这项回顾性临床研究的目的是评估多伦多大学博士前学生提供的实验室制造的整体式后部 LDGC CAD-CAM 牙冠的性能。还调查了特定的患者和提供者相关因素。

材料与方法

评估了由博士前学生提供的后部 LDGC CAD-CAM 牙冠 (IPS e.max) 样本。根据特定标准制备牙冠，并在内部实验室使用 CEREC Bluecam 系统研磨牙冠。牙冠用 Rely-X Unicem (3M ESPE) 和 Calibra Universal (Dentsply Sirona) 树脂粘固剂粘固。牙冠和支持牙周结构的临床评估是按照修改后的加州牙科协会 (CDA) 标准进行的。获得口内照片以及根尖周和咬翼射线照片，以供 2 名评估者进一步评估。描述性统计，McNemar，t检验、对数秩 (Mantel-Cox) 检验、Pearson 卡方检验、简单逻辑回归、优势比和 Kaplan Meier 生存分析 (α=.05)。

结果

共有 189 名接受 210 颗牙冠（108 颗前磨牙和 102 颗磨牙）的患者接受了长达 6 年的随访。总共观察到 28 种并发症（12 种技术并发症、11 种生物并发症和 5 种美学并发症）。在患者年龄、性别、牙周状况、牙齿类型、牙齿活力、水泥类型和牙冠寿命之间没有发现显着相关性。然而，下颌牙冠的存活率和成功率显着低于上颌牙冠 ( P =.029)。提供者的经验对 LDGC CAD-CAM 牙冠的临床表现没有显着影响。6年累计生存率为93.0%，成功率为86.4%。

结论

CAD-CAM 系统的易用性和 LDGC 的临床性能表明，该技术应该由博士前学生在牙科学校环境中使用。