Marginal bone changes in cement-retained implant-supported crowns: A systematic review and meta-analysis

Despite extensive research on the individual factors associated with marginal bone changes around cement-retained implant-supported crowns, there remains a substantial knowledge gap concerning the cumulative impact of multiple factors on this outcome.

The purpose of this systematic review and meta-analysis was to identify factors associated with marginal bone changes around cement-retained implant-supported crowns and to compare these bone changes with those of screw-retained implant-supported crowns.

A comprehensive literature search was conducted in the PubMed, Embase, and Scopus databases before November 2024, supplemented by a manual search of relevant reference lists. Two independent reviewers screened studies, extracted data, and assessed study quality. The included studies involved bone-level dental implants with platform-switching and internal connection designs supporting cement-retained crowns adjacent to natural teeth. Relevant data were extracted and analyzed using meta-regression to identify significant factors influencing marginal bone changes. Pairwise meta-analysis was performed to compare the mean marginal bone changes between cement- and screw-retained implant-supported crowns.

Thirty-one studies, comprising 17 randomized controlled trials (RCTs) and 14 prospective nonrandomized studies, were included in the analysis. Meta-regression analysis revealed that mandibular implant placement was associated with greater bone loss compared with maxillary implant placement. Additionally, baseline bone measurements made at implant loading were linked to less bone loss than those made at implant placement. Certain loading and placement protocols demonstrated lower bone loss, while glass ionomer, zinc phosphate, polycarboxylate, and resin cements were associated with less bone loss compared with zinc oxide cement (P<.05). Over a period of 6 months to 7.5 years, the pooled mean marginal bone change was 0.201 mm (95%CI: 0.147, 0.256) for cement-retained crowns, while for the screw-retained crowns it was 0.105 mm (95%CI: 0.058, 0.151). However, no significant difference in mean marginal bone change was observed between the 2 groups (P=.888).

The findings indicated that several factors significantly impacted marginal bone loss, including implant placement site, baseline marginal bone measurement, implant placement and loading protocols, and cement type. Cement-retained crowns exhibited statistically similar bone loss compared with screw-retained crowns.