Purpose: to evaluate in vitro the residual dentin thickness (RDT) in the bifurcated roots of the maxillary premolars after root canal and post space preparation for ParaPost.
N= 25 extracted bifurcated maxillary premolars
•The teeth were embedded in polyester resin and sectioned horizontally in 3 levels (apical, middle and coronal: at 2, 4 and 6 mm from the apex, respectively).
•the original dentine thickness of the coronal and middle slices of both B and L roots was measured using photographs and a Digitizer at 8 aspects (B, MB, M, ML, L,DL,D,DB). Fig.1
•the slices were reassembled, canals were cleaned and shaped, and Parapost preparation done as follows: GG #2,3; Largo burs #2,3 then Parapost drills #3, 4, leaving t least 5 mm of GP apically.
•The residual dentin thickness of the slices was measured and compared to the original one.
Most highlighted Results:
•In six lingual and buccal root locations, original dentin thickness was 1 mm or less.
•The largest amount of dentin was removed at the lingual aspect of the buccal root (towards the bifurcation), 31.3% where the original thickness was <1 mm.
•Most of the dentin removed from the lingual root was from its buccal bifurcation aspect, both at the coronal and middle levels (27.9 and 21.9%, respectively).
•After post preparation, RDT was less than 1 mm in 12 locations in the two levels of both roots.
•The difference in residual dentin thickness was highly significant regarding procedure (canal and dowel preparation), slice (middle, coronal), and the eight aspects.).
avoid post placement in buccal roots for maxillary PM whenever possible