Role of enamel and dentin on color changes after internal bleaching associated or not with external bleaching

Abstract

Objective To evaluate the effect of the association between external and internal tooth bleaching on color changes in dentin and enamel, individually or recombined, previously stained with triple antibiotic paste (TAP). Methodology Forty enamel-dentin specimens from bovine incisors were separated into ten blocks according to similarity in their whiteness index (WID). Three specimens within each block were stained by dentin exposure to TAP, and the remaining specimen was used as control to estimate color changes. Specimens were sectioned to separate tissues, and dentin and enamel colors were measured individually and after being recombined. Alterations in color (CIEDE2000 - ΔE 00 ) and translucency parameter (TP) resulting from staining were estimated by color difference between stained and control specimens. The contribution of each tissue to the color change (CTCC) was also calculated. Non-sectioned stained specimens were bleached by applying sodium perborate on dentin, associated or not with 35% hydrogen peroxide on enamel. Color changes caused by bleaching procedures were estimated and data were analyzed using the paired t-test or Two-way repeated measures ANOVA. Results TAP caused more pronounced changes in dentin, but enamel color was also affected. Both protocols presented a similar ΔE 00 , and dentin showed the greater color change. After exposure to TAP, we observed a reduction in WID; WID values were the same for bleached and control specimens regardless of protocol. We found no significant effect of substrate and bleaching technique on TP. Enamel played a more critical role in color changes caused by either staining or bleaching procedures. Conclusion Enamel color played a greater role on tooth color changes than dentin. External and internal bleaching association did not improve bleaching effect on specimens stained with TAP.

Assessment of Oxygen Expansion during Internal Bleaching with Enamel and Dentin: A Comparative In Vitro Study

“…Therefore, the marginal sealing of temporary restorations can be affected by bleaching reactions [13,21] Loss of marginal integrity opens a microscopic space between the tooth and the restoration, leading to a cascade of events, such as leakage of bleaching components into the oral cavity, causing an acid taste, irritation, localized desquamation of the adjacent gingival and periodontal tissues, leakage of oral fluids and bacteria into the chamber cavity as well as a decrease in the effectiveness of the treatment [21][22][23][24][25][26]. The exact mechanism explaining peroxides action on each tooth substrate bleaching has not yet been fully elucidated [6,18,27,28], but over the years various authors have demonstrated that intracoronal bleaching agents also reach enamel [29,30].…”

“…[ 1 ] Darkening of a single anterior tooth produces a negative aesthetic effect due to the lack of coincidence in color with the rest of the teeth [ 2 , 3 , 4 ]. Such color alteration may occur after endodontic treatment and/or following trauma due to pulp hemorrhage and necrosis, or as a result of the use of certain endodontic sealing agents, drugs, or restorative materials [ 5 , 6 , 7 ]. Non-vital teeth appear to be darker and more saturated and have an increased hue interval, compared to their vital counterparts [ 1 ].…”

Spectrophotometric analysis of internal bleaching of traumatized teeth with coronal discoloration following regenerative endodontic procedures

“…The REP is an effective therapy for the treatment of necrotic immature teeth, which combines decontamination techniques to eliminate microorganisms from the interior of the root canal and tissue stimulation techniques that will promote the continuation of root development 25 . Despite its clinical success 1,8 , the bond strength of restorative materials is influenced by the biomaterials used as a cervical barrier [26][27] , which can compromise the post-treatment sealing; in addition, some teeth show crown discoloration during the follow-up, often caused by intracanal medications and materials used in the procedure [7][8][9][10][11][12]19 .…”

“…The efficacy of internal bleaching already been proven in several in vitro and in vivo studies that included factors related to REP as etiologies of tooth discoloration, such as the use of MTA as a cervical barrier [30][31] , the use of triple antibiotic pastes 10,19 , or the presence of the blood clot 16 .…”

“…Internal bleaching is a consolidated option for the resolution of cases of coronary discoloration in non-vital teeth, even in cases related to traumatic injuries 17,18 . Recent in vitro studies have shown satisfactory results regarding the efficacy of internal bleaching in darkened teeth after the use of triple antibiotic paste or after the use of calcium silicate-based cervical barriers 10,19 . However, few in vivo studies regarding internal bleaching of teeth treated by regenerative endodontic procedures have been found in the literature [20][21][22][23] , mostly case reports.…”