One‐piece zirconia oral implants for single‐tooth replacement: Three‐year results from a long‐term prospective cohort study

Aim

This 3‐year report of a prospective long‐term cohort investigation aimed to evaluate the clinical and radiographic outcomes of a one‐piece zirconia oral implant for single‐tooth replacement.

Materials and Methods

Sixty‐five patients received a 1‐stage implant surgery with immediate temporization. Standardized radiographs were taken at implant insertion, after 1 year, and after 3 years to monitor peri‐implant bone levels. A univariate analysis of the association of different baseline parameters on marginal bone loss from implant insertion to 36 months was performed. Soft‐tissue parameters were evaluated at prosthesis insertion, after 6 months, after 1 year, and at the 3‐year follow‐up.

Results

After 3 years, six posterior site implants were lost, giving a cumulative survival rate of 90.8%. The mean marginal bone loss was 1.45 mm; 35% of the implants lost at least 2 mm bone, and 22% more than 3 mm. The univariate analysis did not identify any parameter associated with marginal bone loss. Probing depth, clinical attachment level, and bleeding index increased over 3 years, and plaque index decreased.

Conclusions

The low survival rate of the presented ceramic implant and especially the high frequency of advanced bone loss are noticeable but remain unexplained.     

Clinical fit of four‐unit zirconia posterior fixed dental prostheses

The objective of this clinical study was to assess the internal and marginal accuracy of computer‐aided design/computer‐aided manufacturing (CAD/CAM)‐generated four‐unit all‐ceramic posterior fixed dental prostheses (FDPs). The data were compared with the results of three‐unit metal‐ceramic and all‐ceramic FDPs that were obtained in a previous study. Twenty‐four patients were provided with all‐ceramic posterior four‐unit FDPs made from semisintered blank zirconia material. Prior to definitive insertion the accuracy was evaluated using a replica technique with a light body silicone that was stabilized with a heavy body material. The replica samples were examined using microscopy. The median marginal gap of the 24 four‐unit FDPs was 77 μm. The median gap widths were 87 μm at the midaxial wall, 167 μm at the axio‐occlusal transition of the abutments, and 170 μm at centro‐occlusal location. Although the marginal accuracy of the four‐unit FDPs differed significantly from that of the three‐unit metal‐ceramic FDPs (median 54 μm), the values obtained were clinically satisfactory and showed that semisintered zirconia blanks could be used for the fabrication of four‐unit FDPs.     

A practice‐based clinical evaluation of the survival and success of metal‐ceramic and zirconia molar crowns: 5‐year results

This practice‐based study evaluates the survival and success of conventionally luted metal‐ceramic and zirconia molar crowns fabricated by using a prolonged cooling period for the veneering porcelain. Fifty‐three patients were treated from 07/2008 to 07/2009 with either metal‐ceramic crowns (MCC) or zirconia crowns (ZC). Forty‐five patients (26 female) with 91 restorations (obser‐vational period: 64·0 ± 4·8 months) participated in a clinical follow‐up examination and were included in the study. Estimated cumulative survival (ECSv), success (ECSc) and veneering ceramic success (ECVCSc) were calculated (Kaplan–Meier) and analysed by the crown fabrication technique and the position of the restoration (Cox regression model) (P < 0·05). Five complete failures (MCC: 2, ZC: 3) were recorded (5‐year ECSv: MCC: 97·6%, (95% confidence interval (95%‐CI): [93%; 100%]/ZC: 94·0%, (95%‐CI): [87%; 100%]). Of the MCCs (n = 41), 85·0%, [95%‐CI: (77%; 96%)] remained event‐free, whereas the ECSc for the ZCs (n = 50) was 74·3% (95%‐CI): [61%; 87%]. No significant differences in ECSv (P = 0·51), ECSc (P = 0·43) and ECVCSc (P = 0·36) were detected between the two fabrication techniques. Restorations placed on terminal abutments (n = 44) demonstrated a significantly lower ECVCSc (P = 0·035), (5‐year VCF‐rate: 14·8%) than crowns placed on tooth‐neighboured abutments (n = 47), (5‐year VCF‐rate: 4·3%). In the present study, zirconia molar crowns demonstrated a 5‐year ECSv, ECSc and ECVCSc comparable to MCCs. Irrespective of the fabrication technique, crowns on terminal abutments bear a significantly increased risk for VCFs. Clinical investigations with an increased number of restorations are needed.     

Practice‐based clinical evaluation of metal–ceramic and zirconia molar crowns: 3‐year results

This practice‐based study evaluates the clinical performance of conventionally luted metal–ceramic and zirconia molar crowns fabricated with pronounced anatomical core design and a prolonged cooling period of the veneering porcelain. Fifty‐three patients were treated from 07/2008 until 07/2009 with either metal–ceramic crowns (MCC) (high‐noble alloy + low‐fusing porcelain) or zirconia crowns (Cercon System, DeguDent, Germany). Forty‐nine patients (30 women/19 men) with 100 restorations (metal–ceramic: 48/zirconia: 52, mean observational period: 36·5 ± 6 months) participated in a clinical follow‐up examination and were included in the study. Time‐dependent survival (in situ criteria), success (event‐free restorations) and chipping rates (defects of the veneering ceramics) were calculated according to the Kaplan–Meier method and analysed in relation to the crown fabrication technique, using a Cox regression model (P < 0·05). Three complete failures (metal–ceramic: 1, zirconia: 2) were recorded (survival rate after 3 years: metal–ceramic: 97·6%, zirconia: 95·2%). Of the metal–ceramic restorations, 90·9% remained event‐free (two ceramic fractures, one endodontic treatment), whereas the success rate for the zirconia was 86·8% (two ceramic fractures, one endodontic treatment, one secondary caries). No significant differences in survival (P = 0·53), success (P = 0·49) and ceramic fracture rates (P = 0·57) were detected. The combination of a pronounced anatomical core design and a modified firing of the veneering porcelain for the fabrication of zirconia molar crowns resulted in a 3‐year survival, success and chipping rate comparable to MCC.     

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目的 探讨氧化锆全瓷冠桥修复体的修复效果,为临床应用提供参考.方法 对2008年1月至2009年6月佛山市禅城区口腔医院修复科收治的40例接受全瓷修复的患者,采用计算机辅助设计与计算机辅助制作(CAD/CAM)技术制作氧化锆全瓷冠桥修复体60件,其中上颌32件,下颌28件;前牙单冠24个,后牙单冠21个,前牙固定桥2个,后牙固定桥3个(均为3单位固定桥).分别在修复体黏结后1、3、6、12个月对患者进行随访观察,采用美国加利弗尼亚牙科学会的全瓷修复临床标准对修复体的临床效果进行评价,同时也对牙周健康状况进行评价,记录全瓷修复体牙冠的牙龈出血指数(BI)、牙周袋深度(PD)以及附着丧失(AL).结果 观察期间失访3例患者5件修复体,对剩余的37例患者55件修复体的临床观察结果显示,在黏结1个月后有2件修复体的边缘卡探针,有2颗氧化锆全瓷冠修复的牙齿出现牙龈炎.在黏结3个月后,有1个单冠出现裂纹,1例固定桥断裂,2颗牙齿出现牙龈红肿.在黏结6个月后,有1例桩核冠脱落,2颗牙齿出现牙髓炎或根尖周炎.所有复诊患者在12个月的临床观察中均未见边缘着色和继发龋,有5件修复体的颜色匹配稍差.在各时间点BI、PD和AL等指标与治疗前比较差异均无统计学意义(P＞0.05),各项指标比较差异亦无统计学意义(P＞0.05).结论 氧化锆全瓷修复体具有良好的稳定性和生物相容性,近期临床效果满意.     

Four‐year clinical results of fixed dental prostheses with zirconia substructures (Cercon): end abutments vs. cantilever design

The purpose of this prospective study was to evaluate the clinical outcome of three‐ to four‐unit posterior all‐ceramic fixed dental prostheses (FDPs) made of yttria‐stabilized tetragonal zirconia‐polycrystal ceramic frameworks (CerconBase; Degudent). Fifty‐eight restorations were placed in 48 patients. Twenty‐four FDPs had an end abutment design (EAD) replacing 3 premolars and 21 molars. Thirty‐four FDPs had a cantilever design (CD) replacing 11 premolars and 23 molars. The frameworks had a minimum proximal connector dimension of 3 × 3 mm. The fixed dental prostheses were cemented with glass‐ionomer cement after air‐abrading the inner crown surfaces. Three FDPs were defined as drop‐outs. The mean observation period was 48 ± 7 months for the EAD (21 patients/24 FDPs) and 50 ± 14 months for the CD (25 patients/31 FDPs). The 4‐yr survival rate, according to the Kaplan–Meier analyses, was 96% for the EAD and 92% for the CD. The technical complication rate was 13% for the EAD and 12% for the CD, and the biological complication rate was 21% for the EAD and 15% for the CD. For none of the analyses were significant differences found between both groups. After 4 yr the clinical outcome of three‐ to four‐unit posterior FDPs with EAD and CD was promising.