[The protective effect of the bone-augmented subantral barrier after sinus lift on periapical changes of adjacent...

To assess, using cone-beam computed tomography (CBCT), the association between a bone-augmented subantral barrier after sinus floor elevation and radiological signs of apical periodontitis and destructive sinus floor bone changes in adjacent maxillary premolars and molars.

A retrospective comparative clinico-radiological study based on archived CBCT data was performed. The cohort comprised 494 patients (554 teeth) aged 25-75 years: main group - 251 patients (289 teeth) examined 7 years (±3 months) after sinus floor elevation; control group - 243 patients (265 teeth) without sinus floor elevation. The primary analysis of apical periodontitis used generalized estimating equations (GEE) clustered by patient; the adjusted model included group, age, sex, tooth type, and previous endodontic treatment. Inter- and intra-observer agreement was assessed on a 100-tooth subsample.

Apical periodontitis was found in 2.8% (8/289) of main-group teeth vs 9.8% (26/265) of controls: crude OR 0.26 (95% CI 0.12-0.59; p<0.001); GEE OR 0.29 (0.11-0.75; p=0.011). After adjustment the association attenuated to borderline significance: OR 0.38 (0.14-1.05; p=0.063). Destructive sinus floor bone changes were absent in the main group (0/289) and present in 10.2% (27/265) of controls. Observer agreement was substantial to almost perfect: Cohen's kappa 0.73-0.82; ICC(2.1) 0.98-0.99.

A bone-augmented subantral barrier was associated with an approximately 2.5-3-fold reduction in the odds of apical periodontitis and with the absence of destructive sinus floor bone changes in the observed sample. The findings are consistent with a protective barrier hypothesis; causality cannot be inferred. The study is hypothesis-generating and requires prospective confirmation.