Agb. Mentink et al., QUALITATIVE ASSESSMENT OF STRESS-DISTRIBUTION DURING INSERTION OF ENDODONTIC POSTS IN PHOTOELASTIC MATERIAL, Journal of dentistry, 26(2), 1998, pp. 125-131
Objectives: The purpose of this study was to investigate the stress pa
tterns associated with prefabricated endodontic posts during the vario
us stages of insertion according to a number of design characteristics
. Methods: In a photoelastic material with elastic properties comparab
le to dentin, analyses were performed of the overall stress patterns w
ith polarized light revealing substantial differences in stresses gene
rated by the various posts. The effects of variations in design for ce
rtain configurations of the posts were also assessed. Results: One geo
metric feature was the retentive thread of the post. The stress patter
ns within the photoelastic material revealed a homogeneous distributio
n of stress along the entire length of the thread, and more threads in
duced additional stress, The stress recorded with a vent when the pitc
h of the thread was 0.8-1.0 mm was classified as minimal-to-mild stres
s. Another geometric feature considered was the head (coronal extensio
n) of the post. Minimal stress was recorded in the material in contact
with the head and the apical end of the post when the contact surface
of head was more than 3 mm(2). Conclusions: This study suggests that
during insertion of threaded posts the least stress occurs when the he
ad contact surface is sufficient (greater than or equal to 3 mm(2)). A
thread with a pitch of 0.8-1.0 mm is most desirable in stress reducti
on. The number of windings should also be limited (less than six windi
ngs) as samples with a substantial number of windings (N=13 or 30) pro
duce severe stress. (C) 1998 Elsevier Science Ltd. All rights reserved
.