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The impact of endodontic access on the biaxial flexure strength of dentine‐bonded crown substrates – an in vitro study
Author(s) -
Kelly R. D.,
Palin W. M.,
Tomson P. L.,
Addison O.
Publication year - 2017
Publication title -
international endodontic journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.988
H-Index - 119
eISSN - 1365-2591
pISSN - 0143-2885
DOI - 10.1111/iej.12608
Subject(s) - materials science , cementation (geology) , ceramic , crown (dentistry) , composite material , adhesive , flexural strength , dentistry , weibull modulus , medicine , layer (electronics) , cement
Aim To investigate how preparation of a simulated access cavity into ceramic materials suitable for the manufacture of dentine‐bonded crowns ( DBC s) impacted on biaxial flexural strength ( BFS ) determined as a monolithic structure and in a more clinically representative resin‐cemented form. Methodology One hundred and twenty feldspathic and 120 leucite‐reinforced ceramic disc‐shaped specimens were divided into eight groups ( n = 30). All groups received ‘fit’ surface treatments representative of pre‐cementation modifications and of cementation prior to preparation of a representative endodontic access cavity through the sample. BFS was determined for both ‘intact’ and the ‘annular’ disc‐shaped specimens which had received simulated endodontic access. Newly reported analytical solutions were used to calculate BFS of the ‘annular’ specimens. Statistical analysis included two‐way anova s (α = 0.05) and Weibull analysis. Fractographic examination provided insight into the fracture mechanisms. Results A two‐way anova identified a significant impact of material ( P < 0.01) and of resin coating ( P < 0.01) on the mean BFS of intact specimens. For the annular ceramic specimens, the substrate material significantly impacted on mean BFS ( P < 0.01), but the effect of resin coating was dependent on the substrate type ( P < 0.01). Conclusions Endodontic access cavity preparation modified the critical defect population of the all‐ceramic restorative materials investigated. The strength of a predominantly glassy ceramic following endodontic access can be maintained if adhesive cementation was used; however, the beneficial effects of adhesive cementation on ceramic reinforcement were lost on leucite‐reinforced ceramics following access cavity preparation. Replacement restoration for these materials would be recommended clinically following endodontic access as opposed to repair of the access cavity using a direct restorative material.