Files and links (1)
Final Thesis1.24 MB
Embargoed Access, Embargo ends: 06/29/2028
Thesis
Influence of desensitizing agents on the bond strength and surface chemistry of sound and eroded dentin
University of Iowa
Master of Science (MS), University of Iowa
Spring 2026
Abstract
Objective: Desensitizing agents are commonly used to manage dentin hypersensitivity, yet their application may influence dentin surface characteristics and subsequent adhesion. This study evaluated the effects of commonly used desensitizing agents on dentin surface chemical characteristics and on the resin-dentin bond strength of sound and eroded dentin after 24 hours and 6 months of aging. Methods: Eighty extracted sound human premolars were flattened on the buccal surface to expose dentin and randomly assigned to sound or eroded groups. Erosion was induced by citric acid cycling (1% citric acid, pH 2.4, 5 min, 3×/day) with storage in simulated body fluid (SBF) between cycles. Specimens then received one of four treatments (n = 10): (1) no treatment (control), (2) glutaraldehyde-based desensitizer (Gluma®, Kulzer), (3) nanohydroxyapatite-based desensitizer (Predicta Bioactive Desensitizer®, Parkell), or (4) silver diamine fluoride with potassium iodide (Riva Star®, SDI). After desensitizer application, specimens were stored in SBF for 7 days then restored using Scotchbond™ Universal Plus Adhesive and Filtek™ Supreme Ultra Universal Restorative (3M Oral Care). Resin-dentin beams were sectioned and tested for microtensile bond strength after 24 hours and 6 months of storage in SBF at 37 °C using a universal testing machine (Zwick/Roell) at a crosshead speed of 0.5 mm/min. A separate set of forty premolars was prepared for Raman spectroscopy by flattening the buccal dentin surfaces and allocated to the same sound/eroded and treatment groups (n = 5). Surface spectra were acquired using a micro-Raman spectrometer at baseline, immediately after desensitizer application, and after 7 days of storage in distilled water. Phosphate, carbonate, and collagen-associated bands were analyzed, and peak intensity/area ratios were calculated to detect treatment-related changes in dentin surface chemical composition. Statistical analysis of bond strength and Raman spectroscopy outcomes was performed using three-way ANOVA. Post hoc comparisons were adjusted using the Šidák correction, and statistical significance was set at α = 0.05.
Results: Tooth condition and aging significantly affected microtensile bond strength. Sound dentin showed higher bond strength than eroded dentin (p < 0.001), and bond strength decreased after 6 months compared with 24 hours (p < 0.001). Significant interactions were observed between tooth condition and measurement time (p = 0.003) and between material and measurement time (p = 0.020). At 24 hours, SDF+KI showed significantly lower bond strength than the control (p < 0.001) and Gluma groups (p < 0.001). At 6 months, Gluma showed significantly higher bond strength than SDF+KI (p = 0.009). Raman spectroscopy showed significant effects of tooth condition, material, timepoint, and/or their interactions on the reported surface chemical ratios, indicating that dentin surface composition varied according to substrate condition and treatment.
Conclusion: Desensitizing agents significantly influenced resin-dentin bond strength and had some effects on dentin surface chemistry, with outcomes dependent on substrate condition and aging period. Gluma demonstrated the most favorable overall bonding performance, whereas SDF+KI adversely affected bond strength, particularly at 24 hours. These findings highlight the importance of desensitizing agent selection when restorative treatment is planned, especially for eroded dentin.
Details
- Title: Subtitle
- Influence of desensitizing agents on the bond strength and surface chemistry of sound and eroded dentin
- Creators
- Noor Khaled Asfar
- Contributors
- Ariene Leme-Kraus (Advisor)Cristina Vidal (Committee Member)Erica Teixeira (Committee Member)Robert Bowers (Committee Member)Shareef Dabdoub (Committee Member)
- Resource Type
- Thesis
- Degree Awarded
- Master of Science (MS), University of Iowa
- Degree in
- Oral Science
- Date degree season
- Spring 2026
- Publisher
- University of Iowa
- Number of pages
- xi, 94 pages
- Copyright
- Copyright 2026 Noor Khaled Asfar
- Language
- English
- Date submitted
- 04/28/2026
- Description illustrations
- color illustrations
- Description bibliographic
- Includes bibliographical references (page 88-94).
- Public Abstract (ETD)
Tooth wear near the gumline is common and can expose dentin, the inner part of the tooth. When this happens, many people experience dentin hypersensitivity, a short, sharp pain triggered by cold, hot, sweet, or sour foods and drinks. Dentists often treat this pain with desensitizing products. Still, some of these teeth later need fillings, and it is not fully known whether desensitizing treatments help or interfere with how well those fillings stay in place.
This study examined several desensitizing treatments and their effect on future filling attachment. We compared normal dentin with dentin that had been weakened by acid-related wear. We also evaluated changes in the tooth surface after treatment.
We found that fillings bond better to healthy dentin than to acid-related worn dentin. We also found that attachment generally became weaker over time. The type of desensitizing treatment made a difference, with some treatments appearing more favorable than others. In addition, the tooth surface differed between normal and worn dentin, which may help explain why they responded differently.
These findings are important because tooth wear and sensitivity are common in dental care. A better understanding of these treatments may help dentists relieve pain while also improving the long-term success of fillings.
- Academic Unit
- Oral Pathology, Radiology and Medicine
- Record Identifier
- 9985177374202771
Metrics
1 Record Views