Zirconia compared to titanium dental implants in preclinical studies-A systematic review and meta-analysis

To evaluate whether zirconia implants demonstrate differences in hard and soft tissue integration compared to titanium implants in preclinical studies.

In March 2017, electronic (MEDLINE, EMBASE) and hand search was performed to identify preclinical studies comparing zirconia and titanium implants. Primary outcomes were bone-to-implant contact (BIC) and removal torque out (RTQ), respectively, push-in (PI) measurements. Secondary outcomes included biologic width (BW) dimensions.

A total of 37 studies were included for data extraction after screening of 91 from 1,231 selected titles. Thirty-seven experimental studies using six different species were identified. The follow-up periods ranged between 0.4 and 56 weeks. For titanium, mean values of 59.1% (95% CI: 53.3 - 64.8), 102.6 Ncm (95% CI: 81.5 - 123.6), and 25.1 N (95% CI: 20.2 - 30.0) for BIC, RTQ, and PI were estimated, respectively. The mean values for zirconia were 55.9% (95% CI: 51.6 - 60.1), 71.5 Ncm (95% CI: 51.1 - 91.9), and 22.0 N (95% CI: 13.2 - 30.7) for corresponding parameters. Confounding factors such as animal species, implant material, loading protocol, and study or loading duration significantly influenced the outcomes. Similar qualitative soft tissue integration was reported for zirconia and titanium implants. However, faster maturation processes of epithelial and connective tissues around zirconia implants were assumed. Quantitatively, similar BW dimensions were evaluated for titanium (3.5 mm; 95% CI: 2.9 - 4.2) and zirconia (3.2 mm; 95% CI: 2.7 - 3.7), whereas the loading protocol significantly influenced the outcomes.

Zirconia and titanium implants demonstrate a similar soft and hard tissue integration capacity. However, titanium tended to show a faster initial osseointegration process compared to zirconia. Importantly, not only material characteristics but predominantly animal species and study protocols can significantly influence the outcomes.