J Adv Prosthodont.  2016 Apr;8(2):101-109. 10.4047/jap.2016.8.2.101.

3D micro-CT analysis of void formations and push-out bonding strength of resin cements used for fiber post cementation

• Uzun ÄH
• Malkoç MA
• KeleÅŸ A
• Öğreten

• KMID: 2176646
• DOI: http://doi.org/10.4047/jap.2016.8.2.101

Abstract

PURPOSE
To investigate the void parameters within the resin cements used for fiber post cementation by micro-CT (µCT) and regional push-out bonding strength.
MATERIALS AND METHODS
Twenty-one, single and round shaped roots were enlarged with a low-speed drill following by endodontic treatment. The roots were divided into three groups (n=7) and fiber posts were cemented with Maxcem Elite, Multilink N and Superbond C&B resin cements. Specimens were scanned using µCT scanner at resolution of 13.7 µm. The number, area, and volume of voids between dentin and post were evaluated. A method of analysis based on the post segmentation was used, and coronal, middle and apical thirds considered separately. After the µCT analysis, roots were embedded in epoxy resin and sectioned into 2 mm thick slices (63 sections in total). Push-out testing was performed with universal testing device at 0.5 mm/min cross-head speed. Data were analyzed with Kruskal-Wallis and Mann-Whitney U tests (α=.05).
RESULTS
Overall, significant differences between the resin cements and the post level were observed in the void number, area, and volume (P<.05). Super-Bond C&B showed the most void formation (44.86 ± 22.71). Multilink N showed the least void surface (3.51 ± 2.24 mm2) and volume (0.01 ± 0.01 mm3). Regional push-out bond strength of the cements was not different (P>.05).
CONCLUSION
µCT proved to be a powerful non-destructive 3D analysis tool for visualizing the void parameters. Multilink N had the lowest void parameters. When efficiency of all cements was evaluated, direct relationship between the post region and push-out bonding strength was not observed.

Keyword

Fiber post; Resin cement; Micro ct; Void formation; Push-out bonding

MeSH Terms

Cementation*
Dentin
Resin Cements*
Resin Cements

Figure

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  Fig. 1 Representative micro-CT cross-sections (interval of 500 µm) from the coronal, middle and apical thirds of fiber posts with different resin cement. In the Maxcem Elite cement, fewer, wider, and more voluminous voids (black spots within the cement layers) were formed (A). Multilink N cement had the lowest number of void formations and the smallest area and volume (B). In Super-Bond C&B cement, a large number of narrow and small voids were observed (C).

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  Fig. 2 Regional push-out bonding strength of used resin cements. The highest bond strength was obtained at the coronal level.

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  Fig. 3 Representative image of 3D model of voids. (A) Continuous void formations along the fiber post were wider at coronal third. Insizal view (B) Viewing of same specimen from aproximal (C), (D) Localized void formations in middle third from insizal and aproximal.

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  Fig. 4 (A) Representative images of detected circumferential and open voids in Maxcem Elite. Open voids may act as microbial pathway and penetration area. (B) localized and closed voids in Super Bond C&B. Closed voids weakens the resin cement mechanically. But they protects the interior of tooth from penetration of oral fluids, bacteria and bacterial toxins (D: dentine, C: resin cement, P: post, V: void).

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  Fig. 5 A representative 3D model of fiber post and dispersion of void formations in continuity of post. It is seen that the void formations were the distribution of equal proportion and size in all root region.

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