Ridge dimensions of the edentulous posterior maxilla: a retrospective analysis of a cohort of 127 patients using computerized tomography data

Abstract

Objectives: to evaluate the edentulous ridge dimensions of maxillary posterior sextants with a tridimensional radiographic technique. The influence of the presence/absence of teeth adjacent to the edentulous site on the dimensions of the edentulous ridge was also evaluated.

Material and methods: computerized tomography (CT) scans of 127 patients (65 males and 62 females; mean age: 55.2 ± 10.1 years) with at least one missing tooth in the maxillary posterior sextants were analyzed. On CT cross sections, bone height (BH), bone width (BW) at 1, 3, and 7 mm from the most coronal point of the alveolar crest (BW(1 mm) , BW(3 mm) , and BW(7 mm) , respectively) and the relative vertical ridge position (rVRP) were assessed at the first premolar, second premolar, first molar and second molar edentulous sites.

Results: the results of the study indicate that (i) the maxillary sinus was radiographically evident in about 50% of first premolar sites and 90-100% of second premolar and molar sites; (ii) BH showed a significant decrease from first premolar to molar sites; (iii) BW(1 mm) was higher at second molar site compared with the first and second premolar sites, BW(3 mm) and BW(7 mm) were higher at each molar site compared with each premolar site; (iv) the proportion of sites with BH ≥ 8mm and BWI mm ≥ 6mm was 28.3%, 18.4%, 8.0% and 18.2% [corrected] at first premolar, second premolar, first molar and second molar sites, respectively. The absence of teeth adjacent to the edentulous site negatively affected rVRP, but not BH and BW.

Conclusions: The results of the study indicate that at premolar and molar sites, [corrected] the dimensions of the alveolar crest may call for bone augmentation procedures for proper implant placement in a substantial amount of edentulous patients. When both mesial and distal tooth adjacent to the edentulous site are absent, the placement of implants of adequate dimensions may be more challenging due to a more apical position of the alveolar ridge compared with sites where both adjacent teeth are present.