Ridge dimensions of the edentulous posterior maxilla: a retrospective analysis of a cohort of 127 patients using computerized tomography data Mattia Pramstraller Roberto Farina Giovanni Franceschetti Christof Pramstraller Leonardo Trombelli Authors’ affiliations: Mattia Pramstraller, Roberto Farina, Giovanni Franceschetti, Leonardo Trombelli, Research Centre for the Study of Periodontal Diseases, University of Ferrara, Ferrara, Italy Christof Pramstraller, Medical Centre ‘‘Rovigo,’’ Rovigo, Italy Corresponding author: Prof. Leonardo Trombelli Research Centre for the Study of Periodontal Diseases University of Ferrara Corso Giovecca 203 44100 Ferrara Italy Tel.: þ 39 0532 205277 fax: þ 39 0532 202329 e-mail leonardo.trombelli@unife.it Key words: alveolar process, bone resorption, spiral cone-beam computed tomography, tooth extraction 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  8 mm and BW 1 mm  6 mm was 86.7%, 59.2%, 19.8% and 34.8% 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 second premolar as well as molar sites, 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. A basic requirement for the placement of dental implants is the presence of an ade- quate amount of alveolar bone. When the tooth is still present, however, the vertical amount of alveolar bone may be progres- sively reduced by traumatic injuries or chronic infective/inflammatory diseases, up to tooth exfoliation. Moreover, when single or multiple teeth are lost the alveolar crest undergoes atrophy (Johnson 1969; Pietrokovski & Massler 1967; Schropp et al. 2003; Pietrokovski et al. 2007), and in some instances, may exhibit a reduction in both corono-apical and bucco-lingual Date: Accepted 18 April 2010 To cite this article: Pramstraller M, Farina R, Franceschetti G, Pramstraller C, Trombelli L. Ridge dimensions of the edentulous posterior maxilla: a retrospective analysis of a cohort of 127 patients using computerized tomography data. Clin. Oral Impl. Res. 22, 2011; 54–61. doi: 10.1111/j.1600-0501.2010.01984.x 54 c  2010 John Wiley & Sons A/S