Influence of photodynamic therapy with indocyanine green and methylene blue photosensitizers, and calcium hydroxide intracanal medication on bond strength of glass fiber posts to intraradicular dentin

• Grant number: 21/14486-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2022
• End date: December 31, 2022
• Field of knowledge: Health Sciences - Dentistry - Endodontics
• Principal Investigator: Gustavo Sivieri de Araújo
• Grantee: Fernanda Santos de Melo
• Host Institution: Faculdade de Odontologia (FOA). Universidade Estadual Paulista (UNESP). Campus de Araçatuba. Araçatuba , SP, Brazil

Abstract

Photodynamic therapy (PDT), associated with specific photosensitizers (PSs), is a therapeutic modality that is widely used as an adjunct to conventional endodontic treatment, allowing the microbial reduction present in root canals. However, there are few studies in the literature that assess the effect of indocyanine green PS on the bond strength of intraradicular retainers to root dentin. The aim of the present in vitro study is to evaluate the effects of photodynamic therapy with different photosensitizers, indocyanine green, methylene blue, and the calcium hydroxide intracanal medication on the bond strength of glass fiber posts luted to intraradicular dentin. Forty-eight bovine incisor teeth will be used in this study, which will be submitted to biomechanical preparation (BMP). The teeth will be randomly distributed into six experimental groups according to the photosensitizers used (indocyanine green [IV] activated with infrared laser [» 808nm] or methylene blue [AM] activated with red laser [» 660 nm]), and the use or not of calcium hydroxide intracanal medication (Ca(OH)2) (n =8). The experimental groups will be: G1: BMP + Deionized Water (Negative Control); G2: BMP + Deionized Water + Ca(OH)2 (Positive Control); G3: BMP + IG-PS 50 mg/L + Infrared Laser »=808nm; G4: BMP + IG-PS 50 mg/L + Infrared Laser »=808nm + Ca(OH)2; G5: BMP + MB-PS 50 mg/L + Red Laser »=660nm; and G6: BMP + MB-PS 50 mg/L + Red Laser »=660nm + Ca(OH)2. After the BMP, the intracanal medication will be inserted, remaining inside the root canals for a period of 14 days. Then, the intracanal medication will be removed and the root canals will be obturated and the glass fiber posts luted. The bond strength between the glass fiber posts to the root dentin will be measured through the Push-Out test using the universal testing machine. The bond strength will be assessed in the different thirds of the root dentin (cervical, middle and apical thirds). Furthermore, representative samples from each experimental group will be submitted to Scanning Electron Microscopy (SEM) to qualify the fracture pattern. The data obtained will be submitted to the normality test and the means compared by specific statistical tests (± = 0.05). (AU)