[Clinical outcome of single posterior implant-supported monolithic zirconia crowns fabricated using full digital workflow and conventional workflow: a 3-year follow-up].

Objective: To compare the clinical performance of posterior single implant-supported monolithic zirconia crowns fabricated by full digital workflow and that of those fabricated by conventional workflow. Methods: This is prospective clinical research. Thirty-five patients who participated in a previous study during August 2017 to October 2018 at Department of Prosthodontics, Peking University School and Hospital of Stomatology were included in this 3-year follow-up study. The 35 patients, 17 females and 18 males, aged (49.0±15.4) years (24-86 years old), was allocated into two groups. In the full digital workflow group, intraoral scanning was taken immediately after implant placement, and a full zirconia implant crown was fabricated using model-free computer aided design/computer aided manufacturing (CAD/CAM) procedure (n=14). In the conventional group, a conventional impression was taken 3 months after implant placement and the stone model was produced. A full zirconia implant crown was fabricated using conventional model-based procedure (n=21). Three years following crown delivery, all the prostheses were evaluated in the aspect of color, surface roughness, contour and marginal integrity using modified US Public Health Service criteria (MUSPHS criteria). The soft and hard tissue around implant was evaluated using modified plaque index, probing depth (PD), number of implants with bleeding on probing, marginal bone loss (MBL). The biological and mechanical complication were also recorded. Statistical analysis was performed using independent samples t test, Mann-Whitney U test and Fisher's exact test. Results: The total survival rate of prosthesis and implant was 100% (35/35). No significant difference in MUSPHS criteria ratings on color, surface roughness, contour and marginal integrity of these crowns were found between the full digital workflow group and the conventional group (P>0.05). Sixteen out of the 35 crowns had a contour score of B due to loss of interproximal contact. Ten out of the 35 crowns had the screw hole sealing resin sinking or falling off, four in the full digital workflow group and six in the conventional group. There was no significant difference in the rate of prostheses mechanical complications between the two groups (P=1.000). For all the implants, there was no significant difference in MBL, PD, the modified plaque index, and number of implants with bleeding on probing between the two groups (U=119.50,133.00,142.50, t=-0.53, P>0.05). Conclusions: The clinical performance of implant-supported posterior single monolithic zirconia crowns fabricated by full digital workflow was stable. There was no significant difference in the clinical performance of the single implant crowns between the full digital workflow group and the conventional group.目的： 对比全数字化修复流程与常规修复流程制作的后牙全氧化锆种植单冠的3年临床效果，以期为临床提供参考。 方法： 前瞻性纳入2017年8月至2018年10月就诊于北京大学口腔医学院·口腔医院修复科、拟行后牙全氧化锆种植单冠修复的患者35例，女性17例，男性18例，年龄（49.0±15.4）岁（24~86岁）。分为全数字化组（采用全数字化修复流程制作全氧化锆种植单冠，即种植体植入术后即刻口内扫描，用数字化模型直接制作全氧化锆单冠，共14件）和常规组（种植体植入术后3个月取常规印模，灌制实体模型，模型扫描为数字化模型后制作全氧化锆种植单冠，共21件）。修复后3年对修复体颜色、表面质地、外形、边缘适合性进行评价；检查种植体周围软硬组织健康状况，记录改良菌斑指数、探诊深度、探诊出血、边缘骨丧失量以及机械并发症情况。采用独立样本t检验、Mann-Whitney U检验和Fisher确切概率法进行两组比较。 结果： 修复后3年修复体及种植体的总存留率均为100%（35/35）。两组修复体颜色、外形、表面质地和边缘适合性差异均无统计学意义（P>0.05）。35件修复体中16件修复体出现邻接触丧失。35件修复体中10件螺丝孔封闭树脂下沉或脱落，全数字化组修复体螺丝孔封闭树脂下沉或脱落的发生率（4/14）与常规组［29%（6/21）］的差异无统计学意义（P>0.05）。两组改良菌斑指数、探诊深度、探诊出血和种植体近远中颈部边缘骨丧失量差异均无统计学意义（U=142.50，t=-0.53，U=119.50和133.00，P>0.05）。 结论： 全数字化修复流程制作的后牙全氧化锆种植单冠的3年临床效果稳定，其临床修复效果与常规修复流程相似。.