Effect of initial bone morphology on alveolar bone remodeling following molar extraction: A retrospective study

The clinical evidence about alveolar ridge changes following molar extraction and how the alveolar bone morphology influences the ridge dimensional changes remains limited.

A total of 192 patients with 199 molar extractions were included in this retrospective study. Cone-beam computed tomography (CBCT) images of patients were obtained 0-3 months pre extraction and 6-12 months post extraction. Outcome variables included the change rate in ridge height and width. The effect of morphology on the outcomes was explored by single-factor analysis, correlation analysis, and a multiple linear regression model.

Significant resorption of alveolar bone occurred vertically and horizontally after molar extraction. Jaw, furcation involvement, number of roots, number of bone wall defects, extraction reasons, overall relative bone loss (RBL), bone height of the furcation region, thickness of the lingual/palatal wall, and height difference between buccal and lingual/palatal walls (|HB-HL|) were significantly correlated with the change in the height of the central alveolar bone (HC). The number of bone wall defects, overall RBL, and |HB-HL| were significantly correlated with horizontal width change. HC resorption was higher in sockets with |HB-HL| > 2.5 mm and overall RBL > 50%.

The alveolar bone presented significant resorption after extraction. Anatomical characteristics affected the dimensions of the alveolar bone after molar extraction. When the initial overall RBL was severe or |HB-HL| was larger, the loss of alveolar bone dimensions was even more.

In recent years, it has been demonstrated that the local anatomical morphology of extraction sites may influence the process of alveolar bone remodeling. However, most studies have focused on the anterior teeth, with fewer investigations addressing molar extraction sites. Therefore, we aimed to describe ridge changes following molar extraction and investigate how alveolar bone morphology influences ridge dimensional changes. In this retrospective study, we included a total of 199 alveolar sockets from 192 patients with molar extractions and obtained the corresponding cone-beam computed tomography (CBCT) images 0-3 months pre extraction and 6-12 months post extraction. The results showed significant resorption of the alveolar bone following molar extraction. We found that anatomical characteristics significantly affect the dimensions of the alveolar bone after molar extraction. Specifically, the loss of alveolar bone dimensions was greater when the initial overall relative bone loss (RBL) was severe or when the difference between buccal and lingual/palatal walls was greater.