The position of mental foramen is very important anatomic landmark in dentistry. A dentist can achieve optimal local anesthetic effect and protect mental nerve and artery from unfavorable injury, as long as he knows the position of mental foramen exactly.
The author measured the positions of the mental foramina with 120 orthopan-tomograms of normal adults.
For this study the author divided the cases into three age groups; the first group was form 10 to 29, second group from 30 to 49, and third group from 50 to 69.
The results were as follows.
1. The percentage obtained from the study of the relationships between the mental foramen and the lower teeth showed that the most common location was type Ⅳ in which the mental foramen lay at the apex of the second premolar. The foramen between the apices of the two premolars (type Ⅲ) and the foramen between the second premolar and the first molar (type Ⅴ) occurred often and less often respectively and the foramen below the apex of the first premolar or posterior to the first molar (type Ⅱ, Ⅵ) occurred rare and found no foramen mesial to the first premolar (type Ⅰ).
2. The distance from the occlusal plane to the center of the mental foramen was 32.23±2.74㎜, and apt to increase as aging without exception, and in male (32.73±2,77㎜) was somewhat longer than female (31.74±2.63㎜).
3. The vertical distance from the apex of the second premolar to the center of the mental foramen was 7.43±3.57㎜. And it was jumped in the second group (8.43±3.5O㎜) compared with the first group (5.43±3.53㎜), whereas similar to the third groiip (8.42±3.26㎜). And it was somewhat longer in right side (7.90±3.46㎜) than left side (6.95±3.62㎜), and found no difference between male and female.
4. The horizontal distance from the apex of the second premolar to the center of the mental foramen was 1.14±3.98㎜. And it was slumped in the second group (0.48±3.93㎜) compared with the first group (1.50±2.40㎜), whereas similar to the third group (0.76±4.61㎜). Meanwhile they are somewhat longer in male and left side than female and right side.
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