The effect of implantâ abutment junction position on crestal bone loss: A systematic review and metaâ analysis

PurposeTo investigate the effect of the apicoâ coronal implant position on early and late crestal bone loss (CBL), in bone and tissue level implants.Materials and methodsElectronic and manual literature searches were conducted for controlled clinical trials reporting on CBL before and after functional loading of implants. Random effects metaâ analyses were applied to analyze the weighted mean difference (WMD) and metaâ regression was conducted to investigate any potential influences of select confounding factors.ResultsFourteen articles were included in the systematic review and 12 were included in the quantitative synthesis. For bone level implants, WMD comparing early CBL in equi and subcrestal placement was 0.15 mm (Pâ =â .18). For analyses of late CBL in bone level implants, equi and subcrestal placement revealed a 0.03 mm WMD (Pâ =â .88). Where in supra and subcrestal placement, WMD was 0.04 mm (Pâ =â .86). The comparison presented considerable heterogeneity between these two arms, where the P value for chiâ square test presented as .006. Finally, for CBL between supra and equicrestal placement, WMD was â 0.64 mm (Pâ