Metal-ceramic and monolithic zirconia single crowns lead to similar peri implant marginal bone changes: Study

Monolithic zirconia has excellent mechanical and biologic properties. However, evidence of the clinical properties of implant-supported monolithic zirconia prostheses is limited.

Hence, authors Xiao-tingShen and colleagues from the The Affiliated Hospital of Stomatology, School of Stomatology, Zhejiang University School of Medicine, and Key Laboratory of Oral Biomedical Research of Zhejiang Province, Hangzhou, Zhejiang, PR China conducted this study with the sole purpose to compare the peri-implant marginal bone changes of metal-ceramic and monolithic zirconia single crowns in the posterior region after prosthetic loading.

A total of 224 participants treated with 327 implants restored with either metal-ceramic or monolithic zirconia single crowns in the posterior region were included in this study. Clinical outcomes, including the plaque index, peri-implant probing depth, and bleeding on probing, were recorded, and the marginal bone level was recorded by using the panoramic radiographs obtained at implant placement, second-stage surgery, and the most recent follow-up visit. The included parameters were analyzed with the nonparametric Mann-Whitney tests (α=.05).

The results showed that-

a. The mean follow-up time was 30.4 months, and the cumulative survival rate of implants was 100% and that of the prostheses was 99.1%.

b. The plaque index was 0.46 in the metal-ceramic group, which was significantly higher (P<.05) than 0.37 in the monolithic zirconia group.

c. However, no significant differences (P>.05) were observed in peri-implant probing depth and bleeding on probing between the 2 groups.

d. The marginal bone level at implant placement, second-stage surgery, and the most recent follow-up visit was above the implant platform in both the metal-ceramic and monolithic zirconia groups.

e. The marginal bone changes of the metal-ceramic group was 0.31 mm in the healing period and 0.38 mm in the prosthetic loading period, while in the monolithic zirconia group, it was 0.25 mm in the healing period and 0.43 mm in the prosthetic loading period; no significant differences (P>.05) were observed between the 2 groups.

Therefore, the authors concluded that "The peri-implant marginal bone level change was comparable after prosthetic loading for metal-ceramic and monolithic zirconia single crowns, although monolithic zirconia was associated with reduced plaque."