In vitro studies on the performance of adhesive systems using different etching methods and bulk-fill composites

Author(s)

Maicon Sebold

• Document type: Doctoral Thesis
• Press: Piracicaba, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba
• Defense date: 2021-11-30

Examining board members

Marcelo Giannini; Fábio Dupart Nascimento; Adriana Bona Matos; Fernanda Miori Pascon; Caio Cezar Randi Ferraz

• Advisor: Marcelo Giannini

Abstract

This thesis was divided into three studies. The first study was a narrative review about the history and the technological advancements of dental adhesives. The second study addressed the effect of etchants (37% phosphoric acid, adhesives in self-etch mode, 10-3 solution ? 3% ferric chloride dissolved in 10% citric acid ? and 1.4% nitric acid) on enamel shear bond strength (24 hours), and dentin microtensile bond strength (24 hours and 2 years), from which samples were classified regarding failure mode by scanning electron microscopy (SEM). The Prime&Bond Universal (PBU, Dentsply-Sirona) and Gluma Bond Universal (GBU, Kulzer) adhesives were applied on air-dried dentin previously etched with the abovementioned agents or used in self-etch mode. Application of the adhesives on phosphoric acid-etched, blot-dried dentin was used as control. Enzymatic activity within the hybrid layer (24 hours), and nanoleakage of the bonding interface (24 hours and 2 years) were evaluated. Bond strength tests used 160 teeth (n=10). Nanoleakage (n=5) was evaluated by SEM, whereas enzymatic activity was analyzed by in situ zymography (n=3). The third study investigated dentin bond strength, failure mode, morphology of the bonding interface, adhesive diffusion into dentin, and marginal adaptation of the adhesives Scotchbond Multipurpose (3M Oral Care), Clearfil SE Bond (Kuraray-Noritake), OptiBond All-in-One (Kavo-Kerr), and Futurabond U (Voco) coupled with bulk-fill composites (Admira Fusion x-tra, Voco; Sonic Fill 2, Kavo-Kerr). Class-I cavities were prepared in third molars and restored with the proposed adhesives and composites. Sixty-four teeth were used for the dentin bond strength test (n=8). Failure mode and marginal adaptation (n=3) were evaluated by SEM. Bonding interface morphology and adhesive diffusion (n=3) were analyzed by confocal microscopy. The first study demonstrated research has focused on the modification of adhesive composition to simplify their application, while offering antibacterial effect, enzymatic activity inhibition, and/or remineralization. The second article showed there was no difference among etchants concerning enamel bond strength. At 24 hours, there was no difference in dentin bond strength comparing the phosphoric acid-etched, blot-dried group with 10-3 solution or nitric acid, and mostly adhesive and mixed failures were observed. None of the etching approaches could inhibit dentin enzymatic activity, and all groups presented bond strength reduction after storage. PBU showed less nanoleakage than GBU. In the third article, there was no difference in bond strength among adhesives for SonicFill 2; the bond strength of Admira Fusion x-tra was lower when Clearfil SE Bond was used in comparison with Scotchbond Multipurpose; and the tested composites did not differ between each other. A thick hybrid layer was achieved by Scotchbond Multipurpose. The Futurabond U adhesive led to higher rates of marginal gaps. Overall, the present thesis concludes the determining aspects linked to dentin bonding quality and longevity were influenced by the type of etchant and adhesive system, but not by the type of bulk-fill composite (AU)

• FAPESP's process: 18/09459-0 - In vitro evaluation of alternative dentin conditioning agents based on ferric chloride and citric acid or nitric acid
• Grantee: Maicon Sebold
• Support Opportunities: Scholarships in Brazil - Doctorate