RESUMO
AIM: To investigate the effect of root canal and post-space preparation on the remaining dentine thickness in the apical region of maxillary central and lateral incisors. METHODOLOGY: Fifty extracted maxillary incisors (25 centrals and 25 laterals) were mounted and then sectioned at two levels: 5 and 7 mm from the apex. Computerized images were obtained and a digital image analysis system was used to measure dentine thickness for each section at eight sites: labial, mesial, distal, palatal, mesio-labial, disto-labial, mesio-palatal and disto-palatal. Measurements were repeated at baseline and after both root canal and post-space preparation. Central and lateral incisors were divided into five groups each (n = 5) according to the drill used for post-space preparation: Groups 1 through 4 were prepared using Parapost drills sizes 4.5, 5, 5.5 and 6 respectively. For group 5, size 4 Gates Glidden was used. RESULTS: For both teeth, and at the two levels there was a significant difference (P < 0.001) between the baseline dentine thickness and that remaining after post-space preparation at all sites. There was a statistically significant difference (P = 0.007) between the remaining dentine thickness at 5 and 7 mm at all sites. The average amount of dentine removed ranged from 0.20 to 0.52 mm. In all groups, and for both teeth, some specimens had <1 mm of remaining dentine thickness. CONCLUSIONS: Posts should be used carefully when restoring root filled maxillary incisors.
