Tilted Dental Implants Versus Axial Dental Implants:a Meta-analysis

Objectives:In this study,the clinical effects of tilted implants and axial implants were evaluated by meta-analysis.In order to guide the clinical application,the implant failure rate and marginal bone loss of inclined implant and axial implant in edentulous and partial edentulous patients with a follow-up time of more than 5years were systematically evaluated,subsequently,we describe the complications of fixed dentures with mixed support of tilted implants and axial implants.Method:The electronic search of CNKI,Wanfang database,VIP database,Pub Med,Cochrane Library and web of science was performed,and the searching time from the establishment of the database to October 2021.And the related reviews were manually searched as supplements.Two independent researchers conduct data extraction and literature quality evaluation on the included literature in strict accordance with the established inclusion criteria and exclusion criteria.If there were differences,they will discuss and negotiate with the third researcher.The data collected from the literature were used revman5.3software to meta-analysis.The difference of the implant failure rate and marginal bone loss（MBL）between the tilted implants and axial implants will be calculated in the effect size expressed as mean difference（MD）or risk ratio（RR）.At the same time,the complications of tilted implants and axial implants supported prostheses were described and evaluated.Result:Through electronic search and manually searched,17 studies were finally included in this study.A total of 8191 implants were included,including 3819 tilted implants and 4372 axial implants.The results of meta-analysis showed that in terms of failure rate of implants,there was no significant difference in failure rate between tilted implants and axial implants（RR=0.93,95%CI:[0.73,1.18],P=0.54）;there was no significant difference in implant failure rate between maxillary tilted implants and axial implants in subgroup analysis of failure rate（RR=1.01,95%CI:[0.77,1.34],P= 0.93）,and there was no significant difference in failure rate between mandibular tilted implants and axial implant（RR=0.84,95%CI: [0.37,1.89],P=0.67）.In terms of marginal bone loss of implants,there was a significant difference between tilted implants and axial implants（MD=0.07,95%CI:[0.03,0.11],P=0.001）;there was a significant difference between maxillary tilted implants and axial implants in marginal bone loss subgroup analysis（MD=0.07,95%CI: [0.02,0.11],P =0.004）,there was no significant difference in bone loss between mandibular tilted implants and axial implants（MD=0.06,95%CI:[-0.02,0.14],P=0.1）.The complications of combined application of tilted implants and axial implants in fixed denture restoration include fracture of prosthesis,instability of prosthesis,loosening of screws,peri-implantitis and temporomandibular joint pain.Conclusion:1.When the follow-up time is up to 5 years or more,the failure rate of tilted implants is similar to that of axial implants.2.During the follow-up period of at least 5 years,the tilted implant in the upper jaw has obvious marginal bone absorption than the axial tilted implant,but there is no significant difference in the amount of marginal bone loss in the lower jaw.3.The most common complications of fixed denture with inclined implant and axial implant are prosthesis fracture,screw loosening and peri-implantitis.