Different Post Placement Strategies for the Restoration of Endodontically Treated Maxillary Premolars with Two Roots: Single Post vs Double Post.

Aim And Objective: The present study compared the fracture strength and failure pattern of endodontically treated, bi-rooted, maxillary premolars with different number of coronal walls and postendodontic restoration (one vs double post).

Materials And Methods: 105 premolars were divided into 3 groups according to the number of residual walls: control group (intact teeth; = 15), group 1 (3 residual walls; = 45), group 2 (2 residual walls; = 45). Each test group was then divided into 3 subgroups ( = 15 each) according to postendodontic restoration: no post (A), 1 post (B) or 2 posts (C). A load was applied parallel to the longitudinal axis of the teeth, thus simulating physiological occlusion. ANOVA and Tukey's tests were used to detect fracture strength differences among groups, while Chi-square test was used to check differences in fracture pattern.

Results: No significant differences were observed between control group (intact teeth) and groups A1 ( = 0.999), B1 ( = 0.997) and C1 ( = 1.000); statistically significant differences were detected between control group and groups A2 ( < 0.001), B2 ( < 0.001) and C2 ( < 0.05). Different post placement techniques were non-significantly associated with fracture pattern in both groups 1 ( = 0.666) and 2 ( = 0.143) while, irrespective of the number of posts, the presence of the post was significantly associated with the fracture pattern in teeth with two residual walls. The double-post technique did not further improve the fracture resistance of hardly damaged endodontically treated maxillary bi-rooted premolars compared to single-post technique. Therefore, the insertion of a single post in the palatal canal could be a safer and more conservative choice.

Clinical Significance: The double-post technique did not further improve the fracture resistance of severely structurally compromised endodontically treated maxillary premolars with two roots compared to the single-post technique. Therefore, the safer and less invasive treatment is the placement of a single post in the palatal canal.