Effect of Selective Etch on the Bond Strength of Composite to Enamel Using a Silorane Adhesive

At a Glance

Metadata	Details
Publication Date	2015-08-05
Journal	Operative Dentistry
Authors	L Bermudez, Michael Wajdowicz, Deborah L. Ashcraft‐Olmscheid, KS Vandewalle
Institutions	Keesler Medical Center, Uniformed Services University of the Health Sciences
Citations	3
Analysis	Full AI Review Included

Technical Documentation & Material Solutions Analysis (6CCVD)

Research Paper: Effect of Selective Etch on the Bond Strength of Composite to Enamel Using a Silorane Adhesive Source: Operative Dentistry, 2015, 40-6, E242-E249

Executive Summary

This study successfully quantified the shear bond strength (SBS) of three two-step self-etch adhesive systems (LS System, Clearfil SE Bond, OptiBond XTR) to bovine enamel, focusing on the impact of prior selective etching with phosphoric acid.

Core Achievement: Demonstrated a statistically significant increase in composite-to-enamel bond strength across all adhesive types when enamel was selectively etched using 35% phosphoric acid (p<0.01).
Performance Comparison: Methacrylate-based adhesives (Clearfil SE Bond and OptiBond XTR) exhibited significantly higher bond strengths overall compared to the silorane-based LS System Adhesive.
Durability: No significant difference in SBS was found between specimens stored for 24 hours and those stored for six months in 37 °C distilled water, confirming short-term durability.
Interface Stability: Selective etching resulted in a higher incidence of mixed and cohesive fracture modes, indicating a more stable and mechanically robust bond interface compared to purely adhesive failure.
Methodology Note: High-precision material preparation was critical, relying on specialized tooling, including water-cooled diamond saws for sectioning and diamond wheel burs for surface flattening.
6CCVD Relevance: The requirement for high-precision cutting, flattening, and low-roughness surface preparation highlights the demand for high-quality, custom-fabricated CVD diamond tools and substrates in rigorous biomedical testing environments.

Technical Specifications

The following hard data points define the materials tested and the experimental conditions utilized in the study:

Parameter	Value	Unit	Context
Etchant Concentration	35	%	Phosphoric acid used for selective etching
Etching Time	15	s	Duration of phosphoric acid application
Light Curing Irradiance	>1000	mW/cm²	Minimum acceptable intensity from Bluephase G2 unit
Testing Speed	1	mm/min	Crosshead speed on Instron universal testing machine (shear mode)
Storage Temperature	37	°C	Distilled water storage condition
Maximum Mean SBS (Etch-and-Rinse)	30.9 (SD: 7.9)	MPa	OptiBond XTR, 6 months
Minimum Mean SBS (Self-Etch)	14.2 (SD: 3.3)	MPa	LS System Adhesive, 6 months
Mean Total SBS (Etch-and-Rinse)	26.4 (SD: 7.0)	MPa	Average across all agents/times
Mean Total SBS (Self-Etch)	19.7 (SD: 5.6)	MPa	Average across all agents/times
Specimen Bond Area Diameter	2.4	mm	Defined by white plastic mold

Key Methodologies

The following is an outline of the critical preparation and testing steps, emphasizing the requirements for precision tooling:

Specimen Acquisition and Storage: Bovine incisors stored in 0.5% chloramine-T and used within three months.
Rough Sectioning: Crowns were sectioned buccolingually using a water-cooled diamond saw (Isomet 5000) at the cementoenamel junction to remove roots.
Retention Preparation: Retention cuts were placed on the lingual surface to prevent dislodgement during testing.
Surface Flattening: A small area of exposed enamel was flattened using a diamond wheel bur mounted in a drill press (Proxxon).
Surface Smoothing: Flattened enamel surfaces were smoothed using 600-grit silicon-carbide paper (Norton Abrasives).
Selective Etching (Etch-and-Rinse Groups): 35% phosphoric-acid gel applied for 15 seconds, rinsed for 15 seconds, and lightly air-dried for 3 seconds.
Adhesive Application: Two-step self-etch adhesives (LS System, Clearfil SE, OptiBond XTR) applied per manufacturer instructions and light cured (10 s).
Composite Placement: Composite restorative material (Filtek LS or Filtek Supreme Ultra) placed incrementally (two increments, 3-4 mm total height) and light cured (10 s per increment).
Storage and Testing: Specimens stored in distilled water at 37 °C for 24 hours or 6 months. Shear bond strength (SBS) measured using a universal testing machine (Instron Model 5943) with a knife-edge blade.

6CCVD Solutions & Capabilities

This research relies heavily on precise material processing—specifically sectioning, grinding, and surface finish control—which are core applications benefiting from Monocrystalline (SCD) and Polycrystalline (PCD) MPCVD Diamond manufactured by 6CCVD. Our materials ensure the required stability, wear resistance, and geometric accuracy for replicable biomedical tests.

Research Requirement	6CCVD Material/Capability	Value Proposition for Engineers
High-Volume Precision Sectioning	Custom PCD Wafers/Plates (Up to 125 mm)	Supply of ultra-hard, large-format Polycrystalline Diamond (PCD) substrates, ideal for manufacturing highly durable, water-cooled cutting wheels (e.g., Isomet saw blades) with minimal kerf loss and superior edge retention required for sample preparation.
Repeatable Surface Flattening	Custom-Machined SCD/PCD Components	Engineering and fabricating complex diamond geometries (e.g., custom diamond wheel burs, micro-milling heads) using advanced laser and CNC processes. We deliver tools with tight dimensional tolerances critical for preparing standardized flat enamel surfaces.
Ultra-Low Roughness Finishing	Optical Grade SCD Wafers (Ra < 1 nm)	SCD materials available with exceptional polish (Ra < 1 nm). These can be used as high-precision lapping surfaces or reference substrates to calibrate grinding processes, ensuring researchers achieve a precise, verifiable roughness standard far superior to commercial SiC paper.
Environmental Control Substrates	Substrates up to 10 mm Thickness	Provision of thick SCD or PCD plates (up to 10 mm). Diamond’s extreme thermal conductivity and low coefficient of thermal expansion (CTE) make these ideal mounting blocks for dental specimens, ensuring stability during curing cycles and minimizing temperature-induced stress during long-term storage or mechanical testing.
Advanced Sensor Integration	Custom Metalization (Ti/Pt/Au/Cu)	For future iterations of adhesion studies involving electrical impedance or localized heating, 6CCVD provides in-house metalization services (Au, Pt, Ti, W, Cu) on diamond substrates, enabling the integration of micro-sensors directly into the test jig or mounting apparatus.

Applicable Materials

To replicate or extend this research requiring high-precision mechanical modification and reliable thermal performance, 6CCVD recommends:

Polycrystalline Diamond (PCD): For high-wear cutting applications (saws, grinding wheels) where toughness and durability are paramount. Supplied in custom dimensions up to 125 mm.
Single Crystal Diamond (SCD): For extremely fine micro-machining tools or high-tolerance polishing surfaces where a consistent, low-roughness finish (Ra < 1 nm) is required.

Engineering Support

6CCVD’s in-house PhD team specializes in CVD diamond mechanics and thermal properties. We offer direct consultation to assist engineers in selecting and designing custom diamond tooling (cutting, polishing, and grinding components) required for robust biomaterial adhesion testing and other precision mechanical experiments.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

SUMMARY An improvement in bond strength to enamel has been demonstrated with the use of phosphoric acid prior to bonding with self-etch methacrylate-based adhesive agents. No research has evaluated the effect of phosphoric-acid etching of enamel with a newer self-etch silorane adhesive. The purpose of this study was to evaluate the shear-bond strength of composite to enamel using the self-etch silorane adhesive compared to other self-etching methacrylate-based adhesives, with or without a separate application of phosphoric acid. Bovine incisors were sectioned using a diamond saw and mounted in plastic pipe. The bonding agents were applied to flattened enamel surfaces with or without the application of 35% phosphoric acid. The bonded tooth specimens were inserted beneath a mold, and composite was placed incrementally and light cured. The specimens were stored for 24 hours and six months in water and tested in shear. Data were analyzed with a three-way analysis of variance (ANOVA) to evaluate the effects of surface treatment, adhesive agent, or time on the bond strength of composite to bovine enamel (α=0.05). Significant differences were found between the groups based on surface treatment (p&lt;0.01) or adhesive agent (p&lt;0.01), but not on time (p=0.19), with no significant interactions (p&gt;0.14). Phosphoric-acid etching of bovine enamel significantly increased the bond strength of the self-etch methacrylate and the silorane adhesives. The methacrylate-based adhesives had significantly greater bond strength to enamel than the silorane adhesive.

Tech Support

Original Source

DOI: https://doi.org/10.2341/14-311-l

References

2011 - State of the art of self-etch adhesives [Crossref]
2005 - A critical review of the durability of adhesion to tooth tissue: Methods and results [Crossref]
2005 - Bond strength of self-etch adhesives to pre-etched enamel [Crossref]
2015 - Thirteen-year randomized controlled clinical trial of a two-step self-etch adhesive in non-carious cervical lesions [Crossref]
2010 - Eight-year clinical evaluation of a 2-step self-etch adhesive with and without selective enamel etching [Crossref]
2010 - Clinical performance of a two-step self-etch adhesive with additional enamel etching in Class 3 cavities [Crossref]
2014 - Clinical recipe for durable dental bonding: Why and how?
2010 - Physical properties of a new silorane-based restorative system [Crossref]
2010 - Clinical performance of cervical restorations—A meta-analysis [Crossref]