An in vitro investigation into the effects of retained coronal dentine on the strength of a tooth restored with a cemented post and partial core restoration.

AIM: This study aimed to examine the fracture resistance of teeth restored with cast post and partial cores supported by different heights of coronal tooth structure.
METHODOLOGY: Four specimen groups were prepared. Group A was the control and consisted of 10 single-rooted teeth restored with post and cores cemented in dowel channels with no retained coronal dentine.The test groups, B, C and D differed in the amount of retained buccal coronal dentine having 3, 4 and 5 mm, respectively. All groups were tested to failure using an Instron Universal Testing Machine, Model 1195. The mode of failure for representative specimens for each group was recorded photographically.
RESULTS: Specimens in group B where the remaining dentine core was 3 mm in height fractured at a higher force than specimens in the control group (P = 0.0239). There were no statistically significant differences in the forces required to fracture teeth with retained buccal coronal dentine cores of 4 and 5 mm when compared to the control. There was no statistically significant difference between forces required to fracture groups B and C or groups B and D.
CONCLUSION: In this in vitro study, 3 mm of retained coronal buccal dentine improved fracture resistance of teeth restored with partial post and cores when compared to teeth without retained coronal dentine.