SEM-EDX study of prepared human dentine surfaces exposed to gingival retraction fluids

Olalekan A. Ayo-Yusuf*, Cornel H. Driessen, Andre J. Botha

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


Objectives: To evaluate the effects of gingival retraction fluids (GRF) on prepared dentine surfaces, and to test the null-hypothesis that prior exposure of dentine surfaces for prolonged period to any of the fluids evaluated does not influence acid-etching of the exposed surfaces. Methods: The investigation was carried out using SEM and energy-dispersive X-ray analysis (EDX). The GRF studied were Hemodent™ (HMDT), Astringedent® (AST) and Ultradent® buffered 25% Aluminium Chloride (ULTB). Longitudinal sections of 220-grit ground dentine surfaces were exposed to GRF for 0.5-, 1-, 2- and 5-min (n=4 each). Another group of samples was produced by 20 s application of 35% phosphoric acid (PA) on GRF-pretreated dentine. Control samples were not exposed to GRF. Differences in etching effect - a function of the Ca-contents detected by EDX, were analysed using Friedman's and Wilcoxon's rank test (P<0.05). Results: The SEM demonstrated the presence of a relatively non-porous amorphous dentine matrix, but many of the dentine tubule orifices remained occluded. Granular precipitates, which remained even after acid-etching, were noted on surfaces exposed to Hemodent™ for 5 min. Characteristic crystal growth was observed on surfaces exposed to Astringedent® for 1- or 2-min prior to acid-etching. The EDX data demonstrated that there were differences in resulting Ca-content; ULTB >AST>HMDT>ULTB+PA>HMDT+PA>AST+PA>PA, but AST and HMDT were not significantly different. Conclusions: The exposure of dentine prepared surfaces to these three GRF altered its morphology and reduced the dentine's susceptibility to acid-etching, thus the null-hypothesis is rejected.

Original languageEnglish
Pages (from-to)731-739
Number of pages9
JournalJournal of Dentistry
Issue number9
Publication statusPublished - Oct 2005
Externally publishedYes


  • Acid etching
  • Bonding
  • Dentine
  • Gingival retraction fluids
  • Impression
  • Permeability
  • Smear layer


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