Effect of the addition of the niobophosphate bioactive glass in the gutta-percha: Development, characterization, bond strength to dentin and influence on biofilm formation

Author(s)

Ceci Nunes Carvalho

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Odontologia
• Defense date: 25 abr. 2014

Examining board members

Giulio Gavini; Flaviana Bombarda de Andrade; Vivian Bradaschia Corrêa; José Roberto Martinelli; Fernanda Geraldo Pappen

• Advisor: Giulio Gavini

Abstract

The objectives of this study were to develop and characterize a composite for endodontic obturation based gutta-percha and niobium phosphate glass. The study evaluated the composites micropush-out bond strength to root dentine of the experimental gutta-percha and niobium phosphate glass composite applied with thermoplastic technique to the root canals without sealer in a moist environment and compare to the conventional root canal obturation Ah Plus and gutta-percha, and a commercial bioceramic gutta without sealer. Additionally, the cores materials were characterized using Scanning Electron Microscopic/Energy-dispersive X-ray (SEM/EDS) and Energy Dispersive X-ray fluorescence spectrometry (EDX) analysis. The failure mode was analyzed with SEM. Analysis using EDX and SEMEDS was carried out to verify the composition and distribution of the particles of the tested materials. Data were statistically analyzed by one-way ANOVA and Tukeys test (p < 0,05). Also was analysed the influence of different types of gutta-percha and bioactive niobium phosphate glass on the adherence and biofilm formation by oral bacteria from human dental plaque with Live/dead staining assay using confocal laser scanning microscopy (CLSM). The multispecies biofilm was grown from plaque bacteria on discs of hydroxyapatite - HA, niobium phosphate bioactive glass- VNB, Obtura pellets - OBT, Protaper gutta-percha - PTP, EndoSequence BC gutta-percha - GBC and gutta-percha associated with niobium phosphate glass - GNB in brain-heart infusion broth for 3,14 and 30 days. After the growth induction periods, specimens were stained by using Live/Dead, and the images were analyzed under a CLSM. The total biovolume (mm3), viable biovolume (mm3), and Live percentage (%) were quantified. Biofilm structure was visualized by scanning electron microscopy (SEM). The materials were immersed in phosphate-buffered saline (PBS) and the pH in the solutions was monitored. The materials were also immersed in deionized water and the solutions were analyzed with ICP-OES (Inductively Coupled Plasma - optical emission spectrometry) to determine elemental release. AH Plus and GNB groups showed bond strengths of 2,83 MPa and 2,68 MPa respectively, with no statistically significant difference between them (p > 0,05). GBC group had the lowest bond strength average (1,34 MPa), which was a statistically significant difference compared to the other groups (p < 0,05). Groups GBC, GNB and VNB presented the lowest total biovolume values in 30 days. The highest viable biovolume values in 30 days of incubation, in decreasing order, were as follows: HA; PTP and OBT; GBC and VNB and finally GNB. As regards live percentage, the experimental material GNB presented the lowest values at 3 and 30 days, while VNB presented the lowest value at 14 days, with statistically significant difference in comparison with the other groups (P < 0,05). The experimental material GNB presented the highest pH value after 30 days of immersion in PBS, and greatest Zn release in all the time intervals analyzed when compared with the other groups; and the greatest Ca release at 14 and 30 days, similar to Group GBC, which released a larger quantity of Si when compared with the other groups in the time intervals of 14 and 30 days. The experimental root filling composite (GNB) showed an ability to adhere to root dentine equal to the current gold standard root filling with gutta-percha and sealer (Ah Plus) and was able to inhibit the formation of microbial biofilm when compared to HA and conventional gutta-percha. (AU)

• FAPESP's process: 11/18967-0 - Development and characterization of a composite-based bioactive glass Niobium/Phosphate and gutta-percha for endodontic use: analysis of bond strength to dentin and nanoleakage
• Grantee: Ceci Nunes Carvalho
• Support type: Scholarships in Brazil - Doctorate