Randomized controlled clinical pilot study of all-ceramic single-tooth implant reconstructions: clinical and microbiological outcomes at one year of loading.

OBJECTIVE: To test whether or not pink veneering of the submucosal part of zirconia abutments influences clinical, microbiological and histological outcomes of cemented implant-supported single crowns (ISSC). MATERIALS AND METHODS: A total of 20 patients with one single-tooth implant in the esthetic zone were included. Implants were randomly restored with either pink-veneered zirconia abutments (test group; n = 10) or non-veneered white zirconia abutments (control group; n = 10) and with adhesively cemented all-ceramic crowns. At the 6-month follow-up, soft tissue biopsies were prepared for histological evaluation and microbiological samples were collected around abutments and the respective contra-lateral teeth (in 10 of 20 patients). One year after the initiation of loading, clinical parameters were assessed. Robust linear mixed model and cumulative linked mixed model analyses were performed to investigate the effect of group and time-point on clinical and biological outcomes. RESULTS: Clinical evaluations revealed stable peri-implant soft tissues in terms of probing pocket depth, but a high BOP index (87.5% control; 80.0% test). No statistically significant differences were observed between the test and control group for any outcome measure (P > 0.05). No major biological complications occurred during the observation period. Histological samples revealed a remarkable degree of inflammation in both groups without clear differences in qualitative histological features. Microbiological evaluation demonstrated a slightly higher bacterial count at implants compared to natural teeth at one year of loading without marked differences between groups. CONCLUSION: Limited by a small sample size and a relatively short observation period, pink-veneered zirconia abutments exhibited similar clinical, histological and microbiological outcomes as non-veneered zirconia abutments supporting cemented single crowns.

The Esthetic Effect of Veneered Zirconia Abutments for Single-Tooth Implant Reconstructions: A Randomized Controlled Clinical Trial.

PURPOSE: The purposes of this study were to test whether or not veneering of the submucosal part of zirconia abutments can positively influence the esthetic outcome compared with nonveneered zirconia abutments; to evaluate the influence of the mucosal thickness on the esthetic outcomes of the veneered and nonveneered abutments; and to evaluate the thickness of the peri-implant mucosa compared with the thickness of the gingiva of contralateral tooth sites. MATERIALS AND METHODS: Forty-four single-tooth implants in 44 patients were randomly restored with either cemented (CR) or screw-retained (SR) reconstructions based on white zirconia abutments (CR-W, SR-W) or pink-veneered zirconia abutments (CR-P, SR-P). Esthetic outcome measurements were performed based on a spectrophotometric evaluation of the peri-implant mucosal color. In addition, the thickness of the mucosa was measured. A two-way analysis of variance was conducted to test the effect of veneering (pink vs white) and mucosa thickness (<2 mm vs ≥2 mm) on the calculated color difference ΔE for pooled data of CR and SR reconstructions (p < .05). RESULTS: Analyses grouping the sites according to veneering of the abutments and mucosal thickness demonstrated less discoloration for sites with a veneered abutment irrespective of the mucosal thickness: ΔE 4.50 ± 1.93 (<2 mm) and ΔE 6.88 ± 2.45 (≥2 mm); CR-P, SR-P) compared with sites without veneering ΔE 9.72 ± 3.82 (<2 mm; CR-W, SR-W) and ΔE 8.31 ± 2.98 (≥2 mm). The differences between veneered and nonveneered abutments were significant (p = .032). CONCLUSIONS: Veneering of zirconia abutments with pink veneering ceramic positively influenced the peri-implant mucosal color.

Randomized Controlled Clinical Trial of All-Ceramic Single Tooth Implant Reconstructions Using Modified Zirconia Abutments: Radiographic and Prosthetic Results at 1 Year of Loading.

PURPOSE: This study aims to test whether or not veneering of the submucosal part of zirconia abutments with pink dental ceramic affects radiographic and technical outcomes of implant-supported single crowns (ISSC). MATERIALS AND METHODS: Single tooth implants were randomly restored with either pink-veneered zirconia abutments (test; n = 10) or non-veneered zirconia abutments (control group; n = 10) and all-ceramic crowns. At baseline (crown insertion), and 6- and 12-month radiographic and technical evaluations were performed including standardized x-rays and modified United States Public Health Service criteria (technical). Survival and complication rates were assessed for implants and restorations. Robust linear mixed model analysis was performed to investigate the effect of group and time-point on radiographic outcomes. RESULTS: At 1 year, the survival rate for implants was 100% and 95% for ISSC. Most of the implants were placed subcrestally. Therefore, mean marginal bone levels decreased in both groups between implant insertion and baseline (p < .05), but then remained stable up to 1 year (test: 0.15 mm ± 0.42 mm; control 0.23 mm ± 0.63 mm) (p > .005). At 6 months, one minor chipping occurred in the test group. At 1 year, three crowns (control) exhibited occlusal roughness. In addition, one abutment fracture occurred (test). The differences between test and control group were not statistically significantly different for any of the evaluated outcome measures (p > .05). CONCLUSIONS: Veneering of the submucosal part of zirconia abutments did not affect biological and technical outcomes of ISSCs. Technical complications of the reconstructions, however, were frequent, resulting in a rate of 75% of the crowns being complication free.