Fracture Resistance of Endodontically-treated Teeth: Effect of Combination Bleaching and an Antioxidant

Abstract

SUMMARYThis in vitro study assessed the fracture resistance of endodontically-treated teeth undergoing combination bleaching with 38% and 9.5% hydrogen peroxide gels as in-office and at-home bleaching techniques, respectively. In addition, the effect of an antioxidizing agent, sodium ascorbate, was investigated.Methods and Materials: Sixty maxillary premolars were endodontically-treated, received a glass ionomer barrier as a mechanical seal and were embedded in acrylic resin up to the cemento-enamel junction. The specimens were divided into four groups (n=15) as follows: G I: no bleaching, access cavity restored with resin composite (negative control); G II: bleached for three weeks daily using 9.5% hydrogen peroxide for two hours and three sessions of in-office bleaching using 38% hydrogen peroxide every seven days, then restored (positive control); G III: bleached similar to G II and restored after one week; G IV: bleached similar to G II, along with the use of an antioxidizing agent for 24 hours, then restored. In each in-office and athome bleaching session, the whitening gels were applied to the buccal surface of the tooth and placed inside the pulp chamber (inside/outside bleaching technique). Finally, the specimens underwent fracture resistance testing; the data were analyzed using ANOVA and Scheffé's test (α α=0.05). M Khoroushi • A Feiz • R Khodamoradi Clinical RelevanceThe fracture resistance of endodontically-treated teeth decreases after combination bleaching. The use of sodium ascorbate as an antioxidizing agent reverses decreased fracture resistance. In addition, it decreases the treatment period and the risk of catastrophic crown fractures.

Ex-vivo evaluation of the intrapulpal temperature variation and fracture strength in teeth subjected to different external bleaching protocols

“…These results corroborate those of a previous study (18) that evaluated the flexural strength and modulus of elasticity of bovine teeth bleached with 10% CP during 6 h/day within a 14-day period. Conversely, Khoroushi et al (19) verified that the fracture resistance of endodontically treated teeth decreases after bleaching with different HP bleaching protocols. The structural alterations resulting from the action of the bleaching agents may be reversed by remineralization with fluoride substances (20) or using sodium ascorbate (19).…”

O ascorbato de sódio promove a resistência de união após técnicas de clareamento dental?

“…Others studies have reported that SA can also promote resistance to fracture of teeth after internal bleaching [44] reduce microleakage [45,46,47], and restored the decrease in the Ca/P ratio after bleaching [48]. Khoroushi et al [44] reported that the SA hydrogel gradually attains a yellowish color, and after seven days, it becomes dark yellow to orange [44]. If this gel remains for a long time in contact with the dental substrate, it can reverse the bleaching outcome [44].…”

“…When the antioxidant was applied before bleaching, less damage to the odontoblastlike cells MDPC-23 was found, suggesting the SA solution may protect against the deleterious effect of hydrogen peroxide [43]. Others studies have reported that SA can also promote resistance to fracture of teeth after internal bleaching [44] reduce microleakage [45,46,47], and restored the decrease in the Ca/P ratio after bleaching [48]. Khoroushi et al [44] reported that the SA hydrogel gradually attains a yellowish color, and after seven days, it becomes dark yellow to orange [44].…”

“…Khoroushi et al [44] reported that the SA hydrogel gradually attains a yellowish color, and after seven days, it becomes dark yellow to orange [44]. If this gel remains for a long time in contact with the dental substrate, it can reverse the bleaching outcome [44].…”

Effect of two formulations of 10% sodium ascorbate on fracture resistance of endodontically treated tooth submitted to dental bleaching with hydrogen peroxide associated titanium dioxide nanoparticles

“…28 -After-this-period,-the-pulpchamber-was-washed-with-5.0-mL-distilled-water,-dried-with-an-air-stream-and-restored-in-a-similarmanner-as-described-for-G1.-In-G4-(10SAs),-allprocedures-were-realized-similar-to-G3,-but-afterthe-crown-bleaching,-the-pulp-chamber-was-Nilledwith-10%-sodium-ascorbate-solution-(Aphoticário,-Araçatuba,-SP,-Brazil).--After-the-restoration,-the-teeth-were-againmaintained-at-37°C-and-after-24-hrs-submitted-tof r a c t u r e-s t r e n g t h-t e s t i n g-u s i n g-a n- …”