Gallic acid as a biointeractive dentin conditioning agent for universal adhesives: bond strength, iron retention, and surface characterization following ferric sulfate hemostatic contamination
Clinical Oral Investigations, vol.30, no.7, 2026 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Volume: 30 Issue: 7
- Publication Date: 2026
- Doi Number: 10.1007/s00784-026-06987-5
- Journal Name: Clinical Oral Investigations
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, EMBASE, MEDLINE, Academic Search Ultimate (EBSCO), Natural Science Collection (ProQuest), Biological Science Database (ProQuest), Biomedical Reference Collection: Corporate Edition (EBSCO), Health Research Premium Collection (ProQuest), Pharma Collection (ProQuest)
- Keywords: Dentin adhesion, Dentin contamination, Ferric sulfate, Gallic acid, Restorative dentistry, Universal adhesives
- Open Archive Collection: AVESIS Open Access Collection
- Dokuz Eylül University Affiliated: Yes
Abstract
Objectives: This study evaluated the effects of two universal adhesives, applied under three protocols, self-etch (SE), conventional total-etch (CTE), and modified total-etch (MTE) with 1% (w/v) gallic acid, on shear bond strength (SBS), iron retention, and surface characteristics of noncontaminated and ferric sulfate-contaminated dentin. Materials and methods: One hundred eighty dentin specimens prepared from ninety extracted human molars were allocated to 12 groups (n = 15) by adhesive type (All Bond Universal [ABU] or Tokuyama Universal Bond [TUB]), application protocol (SE, CTE, or MTE), and contamination condition (noncontaminated or 20% ferric sulfate-contaminated [ViscoStat]. After composite build-up and 5,000x thermocycling, SBS was measured. Surface morphology (n = 3, 6 groups) and elemental composition (n = 5, 5 groups) were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). SBS data were analyzed by three-way ANOVA (α = 0.05). Results: All three variables significantly affected SBS (p < 0.001). SE yielded the lowest SBS values (17.46 ± 3.19 MPa) among all protocols (p < 0.001). CTE and MTE protocols showed comparable SBS values (20.30 ± 3.20 vs. 20.80 ± 3.05 MPa; p = 0.591). After ferric sulfate contamination, CTE produced no detectable iron residue, whereas MTE retained iron-associated surface deposits. EDS revealed descriptively higher mineral content in gallic acid-conditioned dentin, and SEM showed protocol-dependent surface patterns. Conclusions: Gallic acid yielded short-term bond strength comparable to phosphoric acid, while inducing a more conservative surface modification. However, gallic acid conditioning following ferric sulfate contamination should be regarded cautiously, as iron-associated deposits are preserved. Clinical relevance: Gallic acid may be considered a conservative preconditioning option for noncontaminated dentin. After ferric sulfate contamination, phosphoric acid remains the more predictable choice given its iron-removal capacity.