Abstract
This study evaluated the fracture resistance of teeth submitted to internal bleaching and restored with different non-metallic post. Eighty mandibular incisors were endodontically treated and randomly divided in 10 groups (n = 8): G1- restored with composite resin (CR), G2- CR + fiber-reinforced composite post (FRC, Everstick post, Sticktech) cemented with resin cement self-etch adhesive (RCS, Panavia F 2.0, Kuraray), G3- CR + FRC + self-adhesive resin cement (SRC, Breeze, Pentral Clinical), G4- CR+ glass fiber post (GF, Exacto Post, Angelus) + RCS, G5- CR + GF + SRC. The G6 to G10 were bleached with hydrogen peroxide (HP) and restored with the same restorative procedures used for G1 to G5, respectively. After 7 days storage in artificial saliva, the specimens were submitted to the compressive strength test (N) at 0.5 mm/min cross-head speed and the failure pattern was identified as either reparable (failure showed until 2 mm below the cement-enamel junction) or irreparable (the failure showed <2 mm or more below the cement-enamel). Data were analyzed by ANOVA and Tukey test (α = 0.05). No significant difference (p < 0.05) was found among G1 to G10. The results suggest that intracoronal bleaching did not significantly weaken the teeth and the failure patterns were predominately reparable for all groups. The non-metallic posts in these teeth did not improve fracture resistance.
Highlights
The discolouration of non-vital teeth due to endodontic treatment can occur by dissemination of blood components into the dentinal tubules, inappropriate access cavity, filling materials remaining in the pulp chamber due to incorrect cavity cleaning and inadequate use of tetracycline-containing medicaments[1,2]
*e-mail: matheus.bandeca@utoronto.ca pigment the dentin into carbon dioxide and water released together with the nascent oxygen[5]. The use of these traditional bleaching materials, especially hydrogen peroxide, has been associated with complications such as cervical root reabsorption, increased dentine permeability, changes in the biomechanical properties of tooth related to alteration in the chemical structure of tooth occurred by demineralization and quantitative mineral loss[6,7]
With the exception of carbon, the other posts showed esthetic more favorable in anterior teeth due to their light-transmitting capacity in addition to their modulus of elasticity values that are similar to that of dentine[15]. This can reduce the risk of tooth fractures and can increase their survival rates when compared to teeth restored with metallic posts[15]
Summary
The discolouration of non-vital teeth due to endodontic treatment can occur by dissemination of blood components into the dentinal tubules, inappropriate access cavity, filling materials remaining in the pulp chamber due to incorrect cavity cleaning and inadequate use of tetracycline-containing medicaments[1,2]. The hydrogen peroxide is widely used in the concentration 30 to 35% with photosensitive components that act as starters to initiate and catalyze the reaction when exposed to light sources[4] The use of these traditional bleaching materials, especially hydrogen peroxide, has been associated with complications such as cervical root reabsorption, increased dentine permeability, changes in the biomechanical properties of tooth related to alteration in the chemical structure of tooth occurred by demineralization and quantitative mineral loss[6,7]. With the exception of carbon, the other posts showed esthetic more favorable in anterior teeth due to their light-transmitting capacity in addition to their modulus of elasticity values that are similar to that of dentine[15] This can reduce the risk of tooth fractures and can increase their survival rates when compared to teeth restored with metallic posts[15]. The purpose of this in vitro study was to evaluate the fracture resistance and failure pattern of teeth submitted to intracoronal bleaching with 35% HP and restored with different procedures
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