Abstract
BackgroundUnderstanding the anatomy of the facial alveolar bone (FAB), provides a prognostic tool for estimating the degree of dimensional ridge alterations after tooth extraction. This systematic review and meta-analysis aims to determine the FAB thickness and modifying factors of anterior maxillary teeth measured by CBCT scans. A secondary objective was to assess the facial distance from the cementoenamel junction (CEJ) to the bone crest.MethodsAn electronic search was made of Medline, Embase, Web of Science, Cochrane Library and Google Scholar up to December 2019. Studies that analyze and quantitatively compare FAB thickness at maxillary teeth by CBCT scans were included. The methodological quality of the included studies was appraised using the ROBINS-I tool and the overall meta-evidence certainty using the GRADE approach. A single means random-effects meta-analysis was performed to obtain the weighted mean for 95% confidence interval. A meta-regression of covariates and subgroup analysis was conducted. The nullity Qh test and I2 index for heterogeneity was estimated.Results2560 potentially relevant articles were recorded from which 29 studies were selected for the qualitative analysis, including 17,321 teeth. Seventeen studies considered the facial bone crest, and 12 the CEJ as a reference point for their measurements. Mean FAB thickness was ≤ 1 mm in maxillary incisors and canines (0.75–1.05 mm) and 1–2 mm in premolars. Patients over 50 years of age, females and thin gingival phenotype was associated with thinner FAB at some apico-coronal locations of maxillary incisors and canines. The geographical setting was an effect modifier that could explain up to 87% of the heterogeneity in FAB thickness, being Asian populations that showed the lowest FAB thickness values. The CEJ-bone crest distance was 2–2.5 mm in all teeth analyzed. Population over 50 years of age exhibited greater CEJ-bone crest distances, and males also showed a trend for greater distance. Evidence certainty has shown moderate quality in most analysis subsets.ConclusionsFacial alveolar bone at anterior maxillary teeth is thin, heterogeneous in width along its apico-coronal dimensions, and increases in thickness in maxillary premolars. The CEJ-bone crest distance presented homogeneous and similar values in all teeth analyzed.
Highlights
Understanding the anatomy of the facial alveolar bone (FAB), provides a prognostic tool for estimating the degree of dimensional ridge alterations after tooth extraction
Understanding the anatomy of the alveolar ridges and FAB thickness provides the clinician with a prognostic tool for estimating the degree of future bone loss after tooth extraction [3]
Some authors decide the timing of implant placement after single tooth extraction according to FAB thickness [10]
Summary
Understanding the anatomy of the facial alveolar bone (FAB), provides a prognostic tool for estimating the degree of dimensional ridge alterations after tooth extraction. Understanding the anatomy of the alveolar ridges and FAB thickness provides the clinician with a prognostic tool for estimating the degree of future bone loss after tooth extraction [3]. The thickness of the FAB is of utmost relevance in the morphological changes of the postextraction alveolus [8]. In this regard, it has been demonstrated that when the thickness is < 1 mm, a mean loss in the height of 7.5 mm occurs after single tooth extraction, while in the cases of thickness ≥ 1 mm, the mean loss in height is 1.1 mm [9]. There is currently no consensus regarding the minimal FAB thickness required to avoid ridge resorption [11]
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