What is the best restoration approach for a cervical non-carious lesion with sclerotic dentine, comparing RM-GIC (Resin Modified Glass Ionomer Cement) sandwich and entirely resin composite in terms of bond strength?

Bond Strength for Cervical Non-Carious Lesion Restoration

Direct Recommendation

For cervical non-carious lesions with sclerotic dentine, use the RM-GIC sandwich technique rather than resin composite alone, as it provides superior retention rates at 3 years and beyond. 1, 2

Evidence Supporting RM-GIC Sandwich Technique

Retention Performance

• The sandwich technique (RM-GIC base with composite overlay) demonstrates significantly better retention than composite resin alone, with a 7.5-fold reduction in restoration loss at 3-year follow-up (RR: 7.5; 95% CI: 2.1 to 27.2; p = 0.002). 1
• At 7 years, RM-GIC restorations showed 88.5% retention compared to only 52.0% retention for composite resin restorations in non-carious cervical lesions. 2
• Glass ionomer cements demonstrate statistically superior retention compared to composite resins (risk difference: 0.07; 95% CI: 0.02,0.12; p = 0.003). 3

Clinical Performance Parameters

• For all other clinical parameters (marginal discoloration, marginal adaptation, secondary caries, color, anatomic form, and surface texture), the sandwich technique performs equivalently to composite resin alone. 1
• The cumulative success rate at 7 years was 58.1% for RM-GIC versus only 30% for composite resin restorations. 2

Why Sclerotic Dentine Matters

Bonding Challenges

• Sclerotic dentine in cervical non-carious lesions presents a particularly difficult substrate for adhesive bonding due to obliterated dentinal tubules and altered collagen structure. 4
• The chemical bonding mechanism of RM-GIC to tooth structure provides advantages over purely adhesive-dependent composite resins in this challenging substrate. 4

Recommended Restorative Protocol

Material Selection Hierarchy

1. First choice: Resin-modified restorative glass ionomer (RM-GIC) as a standalone restoration 4
2. Second choice: RM-GIC liner/base with microfine composite overlay (sandwich technique) 4
3. Third choice: Enamel/dentine bonding agent with microfine composite (use only if RM-GIC unavailable) 4

Technical Considerations

• The sandwich technique involves placing RM-GIC as a base layer (typically 1-2mm) followed by composite resin overlay. 1
• RM-GIC provides chemical adhesion to tooth structure, which is particularly advantageous in sclerotic dentine where mechanical bonding is compromised. 4, 3
• No mechanical preparation is required; rubber dam isolation is recommended for optimal moisture control. 2

Important Clinical Pitfalls

Surface Finish Concerns

• RM-GIC materials demonstrate inferior surface smoothness compared to composite resins, which may affect patient satisfaction initially. 5
• However, this aesthetic compromise is outweighed by the superior long-term retention, particularly in stress-bearing cervical areas. 5, 2

Long-Term Deterioration Pattern

• Composite resin restorations show progressive deterioration in anatomic form, marginal integrity, and retention over time in cervical lesions. 2
• Twelve composite restorations (48% failure rate) were dislodged by 7 years versus only three RM-GIC restorations (11.5% failure rate). 2

Quality of Evidence

• The recommendation for sandwich technique is supported by moderate-quality evidence from systematic review and meta-analysis of randomized controlled trials. 1
• Direct comparative studies consistently demonstrate RM-GIC superiority in retention, the most clinically relevant outcome for restoration longevity. 1, 2, 3
• All secondary outcomes (marginal adaptation, discoloration, secondary caries) show no significant differences between techniques, making retention the decisive factor. 1, 3