Anatomic site evaluation of the zygomatic bone for dental implant placement

Thirty human zygomatic bone specimens (15 females mean age 81.60 +/- 11.38 years, 15 males, mean age 78.47 +/- 6.58 years) were examined by quantitative computed tomography and histomorphometry. The aim of the study was to assess the bone mineral density, the trabecular bone volume and the trabecular bone pattern factor. Moreover, the anterior-posterior and the medio-lateral dimensions and the estimated implant length within the zygomatic bone were determined. For quantitative computed tomography the specimens were scanned together with a bone mimicking anthropomorphic reference phantom. The bone mineral density was calculated for the specimens in the plane of the intended direction of the implant placement. Subsequently, with the sawing and grinding technique, the specimens were prepared in the same plane for histomorphometry. The trabecular bone mineral density was 369.95 +/- 188.80 mg/cm(3) for the female and 398.94 +/- 99.11 mg/cm(3) for the male specimens (P = 0.23). The male trabecular bone volume showed a value of 27.32 +/- 9.49%, while the female group reached a value of 19.99 +/- 7.60% (P = 0.23). The trabecular bone pattern factor was 1.2 X 10(-2) +/- 1.28 mm(-1) for the male and 1.02 +/- 0.96 mm(-1) for the female specimens (P = 0.045). The study reveals that the zygomatic bone consists of trabecular bone with parameters that are unfavourable for implant placement. However, the success of implants placed in the zygomatic bone is secured by the employment of at least four cortical portions.