Relative position of the mylohyoid line on dentulous and edentulous mandibles

For the purpose of studying the relative position of the mylohyoid line, 156 Japanese mandibles (62 dentulous, 94 edentulous) were measured and comparisons made between specimens. Resorption of bone above the level of the mylohyoid line was recognized but no obvious changes were noted below the level of the mylohyoid line, except in rare cases. A straight pattern of the mylohyoid line was observed most frequently, with the segment of the mylohyoid line between the first and second molars being straight. The mean ratio between the total height of the mandible and the height of the mylohyoid line at the level of mesiolingual cusp of the lower first molar was 1:0.65 in males and 1:0.66 in females. These results will be useful in the fabrication of dental prostheses because the level of the occlusal plane can be estimated for edentulous patients using the proportional data for the the mylohyoid line's position.