Inadequate Ridge Height was Significant in Edentulous Maxillary Implant Sites

Objectives: To evaluate the average height and width of posterior edentulous sites in the maxilla and mandible. Maxillary sinus pathology, bony septa, and mandibular lingual undercuts were also analyzed.
Methods: A total of 310 de-identified CBCT scans referred for dental implant therapy were evaluated. Maxillary and mandibular edentulous first molar sites were evaluated by generating cross sectional images to obtain height and width measurements of potential implant sites. The height was measured from alveolar crest to the floor of the maxillary sinus and width was measured half way between crest and sinus floor. In the mandible, the height was measured from alveolar crest to inferior alveolar nerve canal and width was measured 2mm and 6mm apical to the alveolar crest. Additionally, bony septations and mucosal thickening in the maxillary sinus and lingual undercuts in the mandible were evaluated.
Results: The average measurements in the posterior edentulous left and right maxilla were 5.635mm and 5.654mm in height and 8.769mm and 8.632mm in width, respectively. In the left mandible, the sites had an average of 10.835mm in height, 8.265mm at 2mm from the alveolar crest, and 11.086mm at 6mm from the alveolar crest. In the right mandible, the sites had an average of 10.848mm in height, 7.911mm at 2mm from the alveolar crest, and 10.566mm at 6mm from the alveolar crest. Lingual undercuts were found in 33.84% of left mandibular sites and 25.79% of right mandibular sites. Mucosal thickening was present in 24.34% of left maxillary sites and 13.04% of right maxillary sites. Bony septa were present in 10% of left maxillary sites, 2.2% of right maxillary sites.
Conclusions: From an implant planning perspective, this group of patients did not have adequate bone height in the maxillary posterior sites compared to posterior mandibular sites. Bone width was adequate for the majority of maxillary and mandibular sites.