The effect of mesio-distal chamber dimension on access preparation in mandibular incisors.

Because the pulp chamber of a young mandibular incisor flares coronally in a mesio-distal dimension, the access form pictured by a number of authors is triangular in shape. As a person ages, the chamber recedes and the access shape becomes oval in form consistent with a canal system that is primarily bucco-lingual in orientation. Endodontic literature generally recommends either the triangular or oval access shape without acknowledging that both are appropriate at a given time in the life of the individual. The question addressed by this study is when does the pulp chamber loose its coronal flare to become primarily oval in shape, and as a consequence of this change, when should the access form go from triangular to oval. It was concluded that by the age of 40 the canal has decreased in size sufficiently to justify in routine cases an oval preparation of less than 2 mm mesio-distal width.