Ortho-ophthalmic head position

• Main Authors: Kwen-Jing Chen, 陳癸菁
• Other Authors: 賴聖宗
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/41700096452150514485

碩士 === 高雄醫學大學 === 牙醫學研究所碩士班 === 94 === Objective In the 19th century, anthropologist introduced the craniometry for the research of the skull . For the purpose of comparison the difference between the ethnic 、gender and craniofacial relationship , a number of reference lines and planes were defined and the most important of them was the horizontal reference plane. Since the Frankfurt agreement concluded is Germany in 1882 the“Frankfort horizontal plane”has been generally recognized as the reference plane for the skull and frequently been adopted as the horizontal reference line in radiographic cephalometrics. But it had the disadvantages as following:(1)Its reference points were difficultly accessible on cephlometric film.(2)The significant variance of the orbital rim between persons.(3)The ethnic difference of craniofacial morphology.(4)Interindividual variation in the inclination of the intracranial reference line. The concept of natural head position(NHP) was introduced in orthodontics in 1950s. NHP (and the true horizontal) provides a more reliable reference plane cephalometric analysis. But NHP is subjective feeling, and it may be variable accompanying time and habit. NHP has been shown to be correlated to craniofacial morphology, to growth trend and mode respiratory. There were disadvantages for the method to obtain the natural head position. The present study reports the reproducibility of the Ortho-ophthalmic determinated head position. The mean and S.D of the angle between the S-N Line and the true horizontal line through the Ortho-ophthalmic determinated head position were also calculated. Materials & methods The material consisted of a group of students at Kaohsiung medical university —15 females and 15 males. The mean age was 24.3 years. The selective criteria were as following: (1)none of significant craniofacial deformity; (2)The development has been stopped. (3)Never suffered from facial bone fracture; (4)Never suffered from trauma near orbital rim. The head position in this study including:(1)The self-balance natural head position;(2)the closed-eye head position; (3) the Ortho-ophthalmic determinated head position; (4)The estimated head position. All lateral cephalometric recording was performed. The angles between the S-N and the horizontal lines through the four head position were measured. Results The reproducibility of the Ortho-ophthalmic determinated head position was found to be 1.72° and 1.55°(2 weeks). The reproducibility of the estimated head position was found to be 1.73° and 1.55°. The reproducibility of the self-balance natural head position was found to be 1.99° and 2.39°.The reproducibility of the closed-eye head position was found to be 2.78° and 2.39°. The mean value of the angle between the S-N line and the true horizontal line through the Ortho-ophthalmic determinated head position was about 10°.Value for the standard deviation ranged from 3.6°to 4.3°. The mean value of the angle between the Ba-N line and the true horizontal line through the Ortho-ophthalmic determinated head position was about 30.6°.Value for the standard deviation ranged from 3.3°to 4.3°. The mean value of the angle between the S-N line and the true horizontal line through the estimaed head position was about 8.7°.Value for the standard deviation ranged from 3.0°to 3.6°. The mean value of the angle between the Ba-N line and the true horizontal line through the estimaed head position was about 29.4°.Value for the standard deviation ranged from 3.2°to 3.6°. The mean value of the angle between the S-N line and the true horizontal line through the self-balance natural head position was about 8.8°.Value for the standard deviation ranged from 3.7°to 4.1°. The mean value of the angle between the Ba-N line and the true horizontal line through the self-balance natural head position was about 29.4°.Value for the standard deviation ranged from 3.7°to 4.3°. The mean value of the angle between the S-N line and the true horizontal line through the closed-eye natural head position was about 8.8°.Value for the standard deviation ranged from 3.4°to 4.9°. The mean value of the angle between the Ba-N line and the true horizontal line through the closed-eye natural head position was about 29.4°.Value for the standard deviation ranged from 3.4°to 4.3°. Conclusion The Ortho-ophthalmic determinated head position was fairly constant. And the variance of the Ortho-ophthalmic determinated head position is still significantly less than the variance of intracranial reference planes to the horizontal. Through the correct procedure, cephalometric analysis based on the Ortho-ophthalmic determinated head position therefore remains valid.