Objectives:
Extraction of a tooth leads to a series of healing events that are intimately associated with dimensional changes in the alveolar ridge that typically result in a net volume loss. Previous studies have evaluated the extent and pattern of those resorptive changes, however it remains challenging to predict the degree of change that will occur, as numerous local and systemic factors may play a role in the biologic events that follow tooth extraction. The purpose of this study was to assess the role that phenotypic characteristics of the periodontium play in the alveolar ridge remodeling processes that take place following single tooth extraction.
Methods:
Healthy patients in need of a single tooth extraction in the maxillary arch from second premolar to second premolar (inclusive) and who met a predefined eligibility criteria were enrolled in this study. An impression of the maxillary arch was made and a cone beam computed tomography (CBCT) scan of the maxilla was obtained immediately prior to tooth extraction at the baseline visit. At the time of the extraction, clinical measurements were made including probing depth, bone sounding, buccal keratinized mucosa width, buccal and palatal alveolar bone thickness, and buccal and palatal soft tissue thickness. Fourteen weeks following the baseline intervention, patients returned to the clinic for a second impression of the maxillary arch and a second CBCT of the maxilla. Linear and volumetric bone measurements were made using the data obtained from the CBCT scans. The casts obtained from the impressions were digitally scanned and volumetric measurements were made from the digitized data to assess volume changes of the residual ridge. The primary outcome of interest was the volumetric percent reduction of the alveolar ridge following single tooth extraction. Spearman correlations were utilized to evaluate relationships between variables and modeling was completed to predict the percentage of volumetric change in the hard and soft tissues using the clinical variables.
Results:
A total of 21 patients participated in the study, 19 patients are included in this analysis (one patient has yet to complete the study, one patient was later excluded due to lack of compliance). Of the 19 extraction sites included, 17 were maxillary premolar teeth. At baseline, the average buccal plate thickness was 1.09 mm. After 14 weeks, the average loss of alveolar bone width was 1.66 mm. The average loss of buccal bone height was 1.10 mm and mean loss of palatal bone height was 1.36 mm. The average percentage volumetric reduction of the bone as measured from a CBCT scan was 26.42% after 14 weeks of healing. Mean percentage volumetric reduction of the ridge, as measured from a digitized cast, was 18.89%. There was no statistically significant correlation noted between the bone and ridge volumetric measurements.
While there were no statistically significant correlations noted between the thickness of the buccal bone and the amount of volumetric remodeling, statistically significant negative correlations were found between the buccal bone thickness and the loss of alveolar bone width (rs = -0.66418, p-value = 0.0019). In addition, a statistically significant correlation was noted between the reduction in alveolar bone width and the loss of buccal ridge height (rs = 0.55707, p-value = 0.0132). Modeling methods found that increased thickness of the buccal soft tissue was predictive of increased percentage volumetric reduction of hard tissues (coeff = 37.24, p-value = 0.0301).
Conclusions:
Increased buccal soft tissue thickness was found to be predictive of increased percent volumetric reduction of alveolar bone. Thinner buccal bone was correlated with increased loss of alveolar bone width. While statistically significant correlations were identified, further studies with larger sample size are needed to better understand these relationships.