Long-term outcomes of lateral sinus floor elevation: A machine-learning analysis, systematic review, and meta-analysis of predictive factors

Objectives To quantify long-term (>= 5 years) implant survival after lateral sinus floor elevation (LSFE) and to identify clinical predictors of long-term survival using conventional and machine-learning meta-analytic techniques.Methods A systematic search was conducted through MEDLINE, Embase and Scopus. Randomized trials, prospective or retrospective studies with >= 10 patients and >= 5-year follow-up were eligible. Risk of bias was assessed with RoB-2 (RCTs) and the Newcastle-Ottawa Scale (observational studies); certainty of evidence was graded with GRADE approach. A multilevel random-effects meta-analysis (logit-transformed proportions) estimated pooled survival while accounting for clustering of multiple implants per patient. Moderator effects were explored by mixed-effects meta-regression. A MetaForest machine-learning model examined non-linear interactions among predictive factors.Results Thirty-two studies (48 cohorts) involving 7,902 implants and approximate to 2,800 patients met the criteria (3 RCTs, 7 prospective non-randomized, and 22 retrospective studies; follow-up 5-13 years). Pooled long-term survival was 95.8 % (95 % CI: 94.5-96.8 %); Heterogeneity was substantial (I & sup2; = 82.8 %) but fell to 53.2 % in MetaForest residuals. Meta-regression identified lower survival with Graftless procedures versus allografts(beta = 1.11, p = 0.016), autografts(beta =2.40, p = 0.005), Xenografts(beta =1.53, p = 0.04), Xenografts+Allografts(beta =1.55, p = 0.04) and Xenografts+Autografts(beta =1.82, p = 0.03) with no significant difference versus Alloplasts. Residual bone height (RBH) < 4 mm (beta = -0.53, p = 0.039) as well as smoking prevalence (1.96 % per 10 % increase, p = 0.009) reduced survival. MetaForest ranked smoking, age, RBH, follow-up duration and membrane use as the principal predictors; barrier membranes mitigated the negative effect in smokers and in low-RBH sites. Time-to-failure analysis of 205 failed implants showed 59 % of losses within the first year and 96 % by year 5. Overall certainty of evidence was low.Conclusions Implants placed after LSFE exhibit high 5-13-year survival (96 %). Use of bone graft materials and their mixtures yield more favorable outcomes compared to Graftless protocol, whereas RBH < 4 mm and smoking significantly impair implant survival. Barrier-membrane coverage is advisable for smokers and short-RBH sites. Despite the long-term nature of this review (>= 5 years of follow-up), most failures occur within the first three years of function, underscoring the need for intensified monitoring during this early phase.