Surface Treatments that Demonstrate a Significant Positive Effect on the Shear Bond Strength of Repaired Resin-modified Glass Ionomer

Repair Bond Strength of High-viscosity Glass-ionomer Cements Using Resin Composite Bonded with Light- and Self-cured Adhesive Systems

CLINICAL RELEVANCE

High-viscosity glass-ionomer cements (HVGICs) used with atraumatic restorative treatment can be repaired with light- or self-cured adhesive systems; however, the repair bond strength of two-step, self-etching and one-step adhesives in the light-cure mode surpass one-step self-cure adhesives. Working on a feasible self-cure approach in the absence of such in rural areas as well as in war zones is of prime importance.

SUMMARY

In vitro compressive strength and edge stability testing of directly repaired glass-ionomer cements

Objective

To study the repair potential of seven commercial glass-ionomer cements (GICs) using an in vitro edge compression test model.

Materials and methods

A total of 448 normal and 192 repaired cylindrical specimens (6 × 4 mm) were produced from 6 GICs and one resin-modified GIC. Repaired samples consisted of a base aged for 1 month before repaired by an overlying layer. All samples were matured for 1 day, 1 week, 1 month or 3 months before compression, and edge tests were performed respectively on the whole surface (compressive strength, CS) or on the edge (edge stability, ES) using a universal testing machine.

Results

For normal specimens, Ketac Universal (KU) illustrated a significantly higher CS than other groups at all time points (p < 0.001). ES of KU was weaker than EQUIA Forte (EQF), FIX (Fuji IX) and RSC (Riva Self Cure) after 1 day, increasing after 1 week. Repaired specimens showed CS comparable to normal specimens (p > 0.05). Repaired KU significantly improved CS compared to repaired EQF and Fuji II (FII) after 1 day. No statistical difference was found in ES among these groups (p > 0.05).

Conclusions

KU provided the fastest maturation and greatest CS and ES in both normal and repair models after short-term ageing. Repair of GICs could potentially be achieved directly onto the fractured substrate and the subsequent improved mechanical performance could be maintained for at least 3 months.

Clinical relevance

This study provides a potential alternative in-vitro method to assess GIC restoration failure as well as provide insight into the mechanisms of GIC restoration repair.