Abstract: [Abstract] Objective For better use of pigs′ mandibles as models in endodontic surgery, the study assesses the location of the root apex in mandibular first permanent molars in pigs. Methods 48 pigs′ mandibles were selected.
All had sound permanent teeth and the first molars had erupted. The tooth length（distance between dental cusp and root apex location shadowed through bone）, the distance between root apex location and the buccul
surface of the bone, mesiodistal width, buccolingual width, and the length of the clinical crown were measured with a vernier calliper. SPSS software was used to analyze the data. Results The average tooth length was 27.98 mm,
and the average distance between the root apex and buccal surface of the bone was 4.53 mm. Linear regression analysis showed significant relationship between the buccolingual width and tooth length, mesiodistal width and
tooth length. No statistically significant relationship were found in other indices. Conclusion The experiment found that the buccolingual width, mesiodistal width and the average tooth length can be used for predicting the location of the root apex.

Key words:

mandibular first permanent molar in pig, root apex surgery experiment, measurement