The type and architecture of bone are considered to affect its load-bearing capacity and it has been indicated that poorer quality bone is associated with higher implant failure rates. To date, bone classifications have only provided subjective methods for pre-operative assessment, which can be considered unreliable. The aim of this study was to evaluate variations of the bone density in designated endosseous implant sites using computerized tomography. One hundred and thirty-one designated implant sites in 72 patients were utilized. Computerized tomography results indicated that bone densities may vary markedly when different areas of a designated implant site are compared. it has been observed that a difference in the bone density exists for the four regions within the oral area, with the anterior mandible yielding mean density values of 944.9 +/- 207 Hounsfield units (HU) > anterior maxilla, 715.8 +/- 190 HU > posterior mandible, 674.3 +/- 227 HU > posterior maxilla and 455.1 +/- 122 HU. Computerized tomography may be a useful tool for determining the bone density of interest areas before implant placement, and this valuable information about the bone quality provides dental practitioners to make better treatment planning regarding the implant positions.