Objective: To study the anatomic structure of the nasopalatine duct and the neighboring bone,provide reference for implant surgery in the incisor region. Methods: Manual quantitative measurement of the nasopalatine duct were performed in 73 maxilla specimens (38 from male and 35 from female). Results: The angle between the anterior wall of nasopalatine duct and the nasal floor was 114.80??11.00?, the angle between the cortical plate of anterior maxilla and the nasal floor 107.28??10.75?, the length of the nasopalatine duct was (15.63?2.18) mm in male, and ( 14.59 ?1.96) mm in female, the width of nasal opening of the duct was ( 4.92 ?1.46) mm in male, and (5.73?1.50) mm in female, the width of oral opening of the duct was (3.23?0.60) mm in male and (3.83?0.92) mm in female, at the level of nasal floor, the distance between the anterior wall of the duct and cortical plate of anterior maxilla was (6.15?1.90) mm. Conclusion: In front of nasopalatine duct, implants should be implanted parallel to nasopalatine duct,with an angle about 115? between the implant direction and nasal floor. The bone in front of nasopalatine duct was thin,the diameter of implants applied here should be less than 4 mm.

BACKGROUND: The rehabilitation of maxillary loss is based on maxillary prosthesis,and the most difficult problem is that retention and support of maxillary prosthesis can hardly be achieved. The employment of implants in the zygoma region provides good basis for the retention and support of maxillary prosthesis. However,during implantation in the zygoma the pe ripheral tissues may be injured, and even induce failed implantation.OBJECTIVE: To study the bone structure of the zygoma so as to provide reference for implantation in this region.DESIGN:Randomized sampling for repeated observation measurement based on maxilla specimens.SETTING: The research was completed in the prosthodontic department of stomatological college and department of human anatomy of a military medical university.PARTICIPANTS:The experiment was carried out in the Department of Human Anatomy,Fourth Military Medical University of Chinese PLA from March to May 2002. A total of 73 adult maxilla specimens(38 from males and 35 from females) were provided by the Department of Human Anatomy,Fourth Military Medical University of Chinese PLA.METHODS: Quantitative measurement of bone structure of the zygoma region was made with the cursor ruler in the 73 specimens. T-test was used to analyze the measurement data.MAIN OUTCOME MEASURES: The data of measurement: bone thickness of the zygoma, width of the lower part of the zygoma, length of the zygoma, and the distance between lower part of the zygoma and orbital floor.RESULTS: ① Bone thickness gradually decreased from the interior-inferior borderline to the exterior-superior part of the zygoma. In males, the average bone thickness 10 mm,12 mm,14 mm and 16 mm away from the interior-inferior borderline of the zygoma was 6.97 mm, 6.45 mm, 5.75 mm and 5. 01 mm, respectively, in the upper part, and 7.03 mm, 6.69 mm, 6.28 mm and 5.89 mm in the lower part. In females, the average bone thickness 4 mm,6 mm, 8 mm and 10 mm away from the interior-inferior borderline was 6.95 mm,6. 55 mm,6.28 mm and 5.31 mm in the upper part,and 6.60 mm,6. 39 mm,6.26 mm and 5.75 mm in the lower part. ② The lower part of the zygoma was 21.39 mm wide in males and 17.20 mm in females. ③ The average length of the zygoma was 21. 12 mm in males and 19.58 mm in females. ④ The average distance between lower part of the zygoma and orbital floor was 4. 17 mm in males and 3.71 mm in females.CONCLUSION:In maxillary loss,the zygoma is an optimal region for double implants at a distance of more than 15 mm. In males, the implants of 3.6 -4.0 mm in diameter and 10 - 12 mm or 14 - 16 mm in lengthcan be employed; in females, the implants of 3.4 - 3.8 mm in diameter and 4 - 6 mm or 8- 10 mm in length can be employed.The differences in bone quantity between males and females are statistically significant in the zygoma,males' better than females', so they should be treated differently during clinical practice.