Prediction of Residual Alveolar Bone Height in the Posterior Maxilla After Dental Extractions

Abstract

After tooth extraction in the posterior maxilla, bone resorption often limits implant placement unless additional grafting procedures are performed. However, it is difficult to predict the amount of bone that will remain after extraction based on current evidence. The purpose of this study was to develop a method for predicting the postextraction alveolar bone height in the posterior maxilla. The authors conducted a retrospective cohort study that included all patients who were treated for the extraction and replacement of a maxillary first molar with a dental implant from 2008 to 2019. Potential predictor variables included thirteen pre-extraction radiographic measurements obtained via cone-beam computed tomography. The outcome variable was having more than 6mm of bone height from the alveolar crest to the sinus floor after extraction. Decision tree analyses were used to search for the best predictors of this outcome using random forest analysis with a maximum of 3 randomly chosen covariates in each candidate tree. A total of 63 patients were included in the study; 55.6% were women, and the mean age was 57.6±14.5years. In this study population, having a bone height from the furcation to the maxillary sinus floor of <6.7mm had a 7.1% chance of having >6mm of bone height postoperatively, whereas those patients with ≥6.7mm at the same position preoperatively had a 61.9% chance of having >6mm of bone height postoperatively (P<.001). This study suggests that patients with <6.7mm of bone from the furcation to the sinus are at increased risk of having insufficient bone to support a dental implant without additional grafting at the maxillary first molar position. When treating these patients, the surgeon should consider performing a procedure at the time of extraction to increase bone height or explain additional bone grafting is expected for ideal implant placement.