Push-out bond strenght and failure mode of single adjustable and customized glass fiber posts.

Lívia Duarte Santos Lopes a,b, Marlus da Silva Pedrosa c,Lara Beatriz Melo Oliveira b, Sandy Maria da Silva Costa b,Livia Aguiar Santos Nogueira Lima b, Flávia Lucisano Botelho do Amaral a,*

a São Leopoldo Mandic Institute and Research Center, Campinas, São Paulo, Brazil b Course of Dentistry, Centro Universitário UniFacid | Wyden, Teresina, Piauí, Brazil
‍c Department of Biomaterials and Oral Biology, School of Dentistry, University of São Paulo, São Paulo
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Objective: This studyaimed to evaluate the push-out bond strength (PBS) and type of failure of SAP (Splendor®Universal) and CP (composite resin in customized posts) using traditional resincement (RelyX Ultimate) and a dual core self-adhesive (RelyX U200). The resultswere used to determine whether (1) the PBS (MPa) of the CP and Splendor®Universal would change significantly and (2) whether the resin cement and theroot third affect the PBS and the type of failure (adhesive, cohesive, ormixed).
Clinical Implications: The push-out bond strength is clinically important as it evaluates the adhesive capacity between the post, cement, and dentin, preventing future gaps or detachments that could lead to tooth fracture.

Figura 1. Força de adesão push-out (MPa) do pino único ajustável (SAP) e pinos anatomizados (CP) considerando os terços radiculares e cimentos resinosos.

Figura 2. Frequência relativa (%) dos padrões de falhados pinos de fibra de vidro ajustáveis ​​e customizados considerando osdiferentes terços radiculares e cimentos resinosos.

Table 2 lists the different failure types according to the post type, resin cement, and root thirds. Regardless of the root third, when RelyX Ultimate was used, Splendor® Universal showed differences in relation to CP (p < 0.05). Overall, adhesive failure rates were 59% when using CP, but only 38% when using Splendor® Universal. For the self-adhesive resin cement (RelyX U200), regardless of the root third, no significant difference was observed in relation to the type of post (p > 0.05). Splendor® Universal and CP fracture patterns were unaffected by root thirds.

Results:
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‍Regardless of the root third or resin cement, Splendor® Universal showed a statistically higher PBS when compared to CP. According to this viewpoint, Splendor® Universal may have encouraged better post-fitting by creating adhesiveness between the post, sleeve, and cement. There is also the possibility of obtaining mechanical imbrication by sliding the sleeve between the fiberglass post and the canal walls, increasing retention (Angelus, 2020). In addition, applying an auxiliary fiber post during restoration of endodontically treated teeth with enlarged canals significantly increases fracture resistance (Haralur et al., 2018; Li et al., 2011). The Splendor® Universal sleeve may have functioned similarly to an accessory post.

Conclusion:

The Splendor® Universal demonstrated greater bond strength than anatomized posts. The third of the root canal and the adhesive strategy had no effect on the push-out bond strength.