A 3-year prospective study of implant-supported, single-tooth restorations of all-ceramic and metal-ceramic materials in patients with tooth agenesis

Objectives The purpose of this clinical study was to describe outcome variables of all-ceramic and metal-ceramic implant-supported, single-tooth restorations. Materials and methods A total of 59 patients (mean age: 27.9years) with tooth agenesis and treated with 98 implant-supported single-tooth restorations were included in this study. Two patients did not attend baseline examination, but all patients were followed for 3years. The implants supported 52 zirconia, 21 titanium and 25 gold alloy abutments, which retained 64 all-ceramic and 34 metal-ceramic crowns. At baseline and 3-year follow-up examinations, the biological outcome variables such as survival rate of implants, marginal bone level, modified Plaque Index (mPlI), modified Sulcus Bleeding Index (mBI) and biological complications were registered. The technical outcome variables included abutment and crown survival rate, marginal adaptation of crowns, cement excess and technical complications. The aesthetic outcome was assessed by using the Copenhagen Index Score, and the patient-reported outcomes were recorded using the OHIP-49 questionnaire. The statistical analyses were mainly performed by using mixed model of ANOVA for quantitative data and PROC NLMIXED for ordinal categorical data. Results The 3-year survival rate was 100% for implants and 97% for abutments and crowns. Significantly more marginal bone loss was registered at gold-alloy compared to zirconia abutments (P=0.040). The mPlI and mBI were not significantly different at three abutment materials. The frequency of biological complications was higher at restorations with all-ceramic restorations than metal-ceramic crowns. Loss of retention, which was only observed at metal-ceramic crowns, was the most frequent technical complication, and the marginal adaptations of all-ceramic crowns were significantly less optimal than metal-ceramic crowns (P=0.020). The professional-reported aesthetic outcome demonstrated significantly superior colour match of all-ceramic over metal-ceramic crowns (P=0.015). However, no significant differences in the other aesthetic parameters at various restoration materials were registered. After 3years, the patient-reported outcome variables at different restoration materials were not significantly different. Conclusion The biological outcomes at the zirconia and metal abutments were comparable. All-ceramic crowns demonstrated better colour match, but higher frequency of marginal discrepancy compared to metal-ceramic crowns. Generally, the patients noticed no difference in aesthetic outcome of all-ceramic and metal-ceramic restorations.