Prostheses Supported By The Tilted And Axial Implants Jointly:A Systematic Review

Objective:The objective of this review is to systematically analysis the survival rates and complications of the prostheses supported by different proportions of axial implants and tilted implants jointly and to examine the null hypothesis that no difference exist between the tilted and axial implants with aspects to the marginal bone loss and implant success rate.Methods:The electronic search of the Pub Med, Cochrane Library, Sinomed,Embase, Google Scholar, Wanfangdata, CNKI, and Web of Science will be performed. And the manual retrieval will cover a variety of oral medical journals and related meeting literatures in both English and Chinese. The relevant references of the included articles will be scanned as well. In strict accordance with the inclusion criteria and exclusion criteria, the data extraction and offset-risk assessment will be carried out. The null hypothesis test of the differences between the tilted implants and axial implants will be calculated in terms of the implant survival rate and MBL in the effect size expressed as standardized mean difference(SMD) or odds ratio(OR). And the combination of ITT analysis and PP analysis will be made to estimate the effect of drop-out bias. If sufficient homogeneity were detected(I2>50%), the Meta regression model will be fabricated regarding to the study type, the usage of the surgical template, loaded type, the type of dentition, and the implant distribution of the prosthesis to investigate their effects on the homogeneity. The corresponding subgroup analysis will be performed with a fixed effect model according to the results of the Meta regression.Results:The search strategy finally led to 17 studies included. A total of 903 patients, 4110implants(axial implant: 2105; tilt implant: 2005) and 972 dentures were listed. The prostheses survival rates were surpassed 97%. In 1 year follow-up, In 1 year follow-up,both of the odds ratio of the success rate between tilted implant and axial implant by the PP analysis and ITT analysis were 1.056(95%CI 0.56~2.00, P=0.556, Pheterogeneity=0.967);In 3 year follow-up, the odds ratio of the success rate between tilted implant and axial implant by the PP analysis and ITT analysis were 1.343(95%CI 0.643~2.804, P=0.432,Pheterogeneity=0.595) and 1.339(95%CI 0.668~2.687, P=0.869, Pheterogeneity=0.602)respectively. The prostheses survival rates stood at 96.5% to 100%. In regard to MBL, In1 year follow-up, based on the results of the Meta regression analysis and sub-group analysis, the pooled SMD of MBL between tilted implant and axial implant was-1.019(95%CI-1.337~-0.701, P<0.001, Pheterogeneity=0) in sub-group 4:2 in which only 1 study included, and the pooled SMD of MBL were 0.126(95%CI 0.015~0.238, P=0.027,Pheterogeneity=0.308) in sub-group 2:2,-0.193(95%CI-0.432~0.047, P=0.114,Pheterogeneity=0.722) in sub-group 2:4 and 0.079(95%CI-0.195~0.353, P=0.572,Pheterogeneity =0.830) in sub-group 1:1 respectively. In 3 year follow-up, the pooled SMD of MBL between tilted implant and axial implant was 0.166(95%CI-0.034~0.366, P=0.103,Pheterogeneity=0.328).