In vivo evaluation of systemic migration of bismuth and silicon ions from reparative cement in contact with connective tissue

• Grant number: 19/04614-0
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: July 01, 2019
• End date: May 12, 2023
• Field of knowledge: Health Sciences - Dentistry - Endodontics
• Agreement: Coordination of Improvement of Higher Education Personnel (CAPES)
• Principal Investigator: Marina Angélica Marciano da Silva
• Grantee: Lauter Eston Pelepenko Teixeira
• Host Institution: Faculdade de Odontologia de Piracicaba (FOP). Universidade Estadual de Campinas (UNICAMP). Piracicaba , SP, Brazil
• Associated scholarship(s): 20/12327-8 - Cytotoxicity of reparative endodontic materials in direct and indirect contact with different cells, BE.EP.DR

Abstract

Reparative cements such as MTA are widely used in endodontics in procedures that include perforation sealing, pulp capping, apical surgeries, and apexifications. The composition of such cements includes the presence of bismuth oxide, as a radiopacifying agent. Bismuth ions are very reactive and interact chemically with dental structures, resulting in the deposition of a black precipitate that causes dental discoloration. Recent studies have shown that there is a migration of ions from these materials to adjacent tissues. The hypothesis to be tested is that bismuth ions migrate only when combined with silicon ions. The objective of this study is to evaluate the migration of bismuth ions systemically from local application in subcutaneous connective tissue of the commercially available ProRoot MTA cement considering the fluids: blood and cervical-spinal fluid; and also, its accumulation in organs: brain, liver and kidneys. For this purpose, 34 male Wistar rats, 9 weeks old, will be used for evaluation of ProRoot MTA cement (n=10) containing bismuth and silicon (TCS-BiO); compared to tricalcium silicate cement (n=10) containing silicon and bismuth-free (TCS); and with hydroxyapatite + 20% bismuth oxide containing bismuth and silicon-free (HAp-BiO). Two samples of each cement (2 x 4 mm in diameter) will be implanted in the subcutaneous tissue, with each animal receiving two implants of the same cement. As a negative control (n=4), the animals will not receive any type of implant. After the 30-day period, half of the animals (n=17) will be sacrificed and after 180 days the others (n=17). After euthanasia, the total volume of blood, cervical-spinal fluid and organs: brain, liver and kidneys will be collected for analysis in atomic absorption spectrometry to detect the presence of bismuth and silicon ions. The results will be submitted to appropriate statistical analysis with significance level of 5%.