Resin Bonding: RMGIC vs Conventional GIC
Direct Recommendation
For resin bonding applications, Resin-Modified Glass Ionomer Cement (RMGIC) is the preferred choice over conventional GIC due to its superior bond strength to composite resins and better mechanical properties, provided that adequate moisture control can be achieved. 1, 2
Key Performance Differences
Bond Strength to Composite Resin
- RMGIC demonstrates significantly higher shear bond strength to composite resin compared to conventional GIC, with mean values ranging from 4.38-6.13 MPa when bonding agents are used versus lower values for conventional GIC 1
- RMGIC is easily bonded to resins due to its resin component, making it the superior choice for sandwich techniques and layered restorations 3
- When bonding composite to RMGIC, HEMA-free adhesive systems (OptiBond All-In-One) provide greater shear bond strength (6.13±1.859 MPa) than HEMA-based systems (4.38±1.533 MPa) 1
Mechanical Properties
- RMGIC exhibits higher diametral tensile strength (DTS) values ranging from 6.21-22.32 MPa compared to conventional GIC, with the highest values achieved by resin-modified formulations 2
- Compressive strength values are comparable between RMGIC and conventional GIC (90.27-170.73 MPa), though RMGIC shows more consistent early strength 2
- RMGIC demonstrates superior fatigue resistance under mechanical stress, with significantly longer survival times in simulated clinical conditions 4
Critical Moisture Control Considerations
When to Choose RMGIC
- Use RMGIC when optimal moisture control is achievable, as it requires completely dry surfaces for proper adhesion, similar to resin-based materials 5
- RMGIC provides the advantage of long working time combined with rapid set and higher early strength 3
- The American Dental Association emphasizes that ensuring surfaces are completely dry before applying RMGIC is crucial to prevent adhesive failure 5
When to Choose Conventional GIC
- Select conventional GIC when moisture control is compromised or impossible, such as with young, uncooperative children or in field settings 5
- The American Academy of Pediatric Dentistry recommends traditional GIC for managing cavitated lesions when traditional moisture control is not possible 5
- Conventional GIC can tolerate moisture during setting, making it practical for dental therapists and hygienists providing care without optimal moisture control 5
Optimal Bonding Protocol for RMGIC
Surface Preparation
- Apply 15% phosphoric acid etching to enamel surfaces before RMGIC application for maximum bond strength 6
- Ensure complete dryness of all surfaces—moisture will prevent proper adhesion 5, 7
- Avoid water contamination during the bonding procedure, as this significantly reduces bond strength 6
Adhesive Selection
- Prioritize HEMA-free adhesive systems over HEMA-based systems when bonding composite resin to RMGIC for superior shear bond strength 1
- Select appropriate resin cement, as this plays a crucial role in clinical success 7
- Apply the least amount of adhesive necessary to avoid excess material that could cause pooling and complications 7
Common Pitfalls to Avoid
- Do not use RMGIC in situations with inadequate moisture control—this is the most common cause of adhesive failure 5
- Avoid assuming RMGIC has the same moisture tolerance as conventional GIC—it does not 5
- Do not skip acid etching when using RMGIC, as this significantly improves bond strength 6
- Be aware that RMGIC contains free monomers and may not be as biocompatible as conventional GIC, though this is rarely clinically significant 3
Clinical Decision Algorithm
Assess moisture control capability:
- Adequate control available → Proceed to step 2
- Inadequate control (uncooperative patient, field conditions) → Use conventional GIC 5
For adequate moisture control scenarios:
If layering with composite resin: