Parallel post-space preparation in different tooth types ex vivo: deviation from the canal center and remaining dentine thickness.

By Huysmans MC, Klein MH, Kok GF, Whitworth JM.

Date: 06/2008
Journal: JOE

Purpose: to determine the linear deviation of parallel-sided twist-drills during post-space preparation and relate this to tooth type and position.

N = 64 single rooted teeth (16 / group).


•The sample consisted of 4 groups:

1. Group i: Maxillary 2nd premolars

2. Group ii: Maxillary lateral incisors

3. Group iii: Mandibular canines

4. Group iv: Mandibular 1st premolars

•The crowns were sectioned to 17 mm, the teeth were cleaned and shaped and obturated by a standardized protocol (CLC).

•2 operators prepared the post space: the teeth were placed in phantom head, GP removed with GG #2, 3 canals enlarged with Parapost system twist drills #3,4,5 (12 mm length, 1.25 mm diameter).

•Microradiographs were exposed before and after post space preparation  in BL and MD direction and superimposed.

•The canal deviation and remaining dentin thickness was measured.

Most highlighted Results: 

•Overall, the mean deviation was 0.07 mm to the mesial, and 0.27 mm to the buccal.

•Group ii (maxillary lateral) had significantly more buccal deviation than other groups.

•A remaining dentine thickness of <0.5 mm occurred 16 times in 14 teeth, and of <1 mm occurred 97 times in 52 teeth.

Clinical significance:

to avoid perforation and root fracture, if a post has to be used, long parallel posts should be avoided and apically tapered posts should be considered. Root size and root canal morphology should be considered.