Abstract
The endodontic revascularization may be an alternative treatment for necrotic immature teeth, however, several treatment steps may cause tooth discoloration. This study evaluated the use of three calcium silicate-based cements with different radiopacifying agents on the color alteration (∆E) of extracted premolars after simulation of revascularization. Forty single rooted extracted premolars were shaped with #1-6 gates Glidden drills, rinsed with sodium hypochlorite, and filled with fresh human blood. Three calcium silicate-based cements with different radiopacifying agents (bismuth oxide - CSBi, calcium tungstate - CSW, and zirconium oxide - CSZr) were applied over the blood clot (n=10). The control group received the application of a temporary zinc oxide-based cement (TFZn) (n=10). ∆E was measured with a spectrophotometer, using the L*a*b* color system of the International Commission on Illumination (CIELab), in different times: prior to the preparation of the access cavity (t0); right after treatment (t1); and after one (t2), two (t3), three (t4) and four (t5) months. The tooth site for color evaluation was standardized by silicon matrix, the color reading was performed 3 times per tooth, and the teeth were stored in 37º water between evaluations. ∆E, whiteness (WID index) and yellowness (b*) were evaluated. Data were subjected to one-way ANOVA and repeated measures ANOVA, followed by Tukey's post hoc test (α=0.05). All groups were similar in ∆E1 (t0-t1). The ∆E was the lowest and constant in the control group. In all evaluation times, CSBi presented the highest ∆E (p<0.01). CSW and CSZr were similar in all evaluated times and presented intermediate ∆E values. WID index from CSBi and CSW presented more distancing from 'white' reference. CSBi presented the greatest decrease in yellowness (b* value). The cement containing bismuth oxide presented the highest color alteration values. All tested calcium silicate-based cements presented clinically perceptible discoloration. Calcium tungstate and zirconium oxide may be used as alternative radiopacifiers to decrease tooth discoloration after endodontic tooth revascularization.
Highlights
The pulp revascularization promotes deposition of dental hard tissue, resulting in strengthen of root walls and development of a normal apical morphology in immature teeth which suffered necrosis during development [1]
Two or three weeks later, the antibiotic paste is removed with sodium hypochlorite irrigation and an apical bleeding is induced inside the root canal [2], allowing the migration of cells which will promote root thickening and apical closure [5,6]
In the other evaluation times (∆E2, ∆E3, ∆E4, and ∆E5), CSBi always presented the highest values of color alteration, while TFZn presented the lowest values
Summary
The pulp revascularization promotes deposition of dental hard tissue, resulting in strengthen of root walls and development of a normal apical morphology (apexification) in immature teeth which suffered necrosis during development [1]. As a proposed protocol for tooth revascularization [4], after the diagnosis of teeth necrosis, the root canals and pulp chamber are cleaned (light instrumentation and irrigation with sodium hypochlorite) and receive a triple antibiotic paste. The Mineral Trioxide Aggregate (MTA) is the gold standard among biomaterials indicated for covering of exposed pulp tissue It is indicated as the material to be placed over the blood clot during tooth revascularization [4], promoting seal against the penetration of oral bacteria into the pulp space [7]. The MTA produces calcium silicate hydrate and calcium hydroxide on hydration, which will be relevant for deposition of calcium phosphate on the cement surface [8] It presents good results in cell viability and cell migration assays, promoting healing and mineralization activity [9]. MTA presents a radiopacifying agent in its composition and the bismuth oxide was one of the firsts to be used, its destabilization is reported to cause tooth discoloration [10,11]
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