Microshear Bond Strength of Composite Resin to Mineral Trioxide Aggregate and Potassium Nitrate-Modified...

This in vitro investigation evaluated the microshear bond strength (µSBS) of composite resin to mineral trioxide aggregate (MTA) and a modified polycarboxylate cement containing potassium nitrate (PCC/KNO₃), both utilized as pulpotomy materials. The performance of two universal adhesives was compared, applied using self-etch (SE) and etch-and-rinse (E&R) strategies.

A total of 192 cylindrical acrylic specimens (2 cm height × 1 cm diameter) with a central cavity (4 mm diameter × 2 mm depth) were fabricated and filled with either MTA or PCC/KNO₃ (n = 96 each). These were further divided into eight experimental subgroups (n = 12) based on adhesive type (All-Bond Universal or Gluma Bond Universal), adhesive application method (SE or E&R), and storage duration (24 h or 7 days). After resin composite application, all specimens were stored in 100% humidity at 37°C for 24 h prior to µSBS testing. Data were analyzed using four-way ANOVA and independent t-tests (α = 0.05).

PCC/KNO₃ exhibited significantly greater bond strength than MTA at both 24-h (p < 0.001) and 7-day (p = 0.030) intervals. Neither the adhesive type (p = 0.355) nor the application method (p = 0.358) significantly affected bond strength. Over time, µSBS values increased for MTA in some groups, while a significant decline was observed in most PCC/KNO₃ subgroups.

Due to its superior early bond strength and compatibility with immediate restoration, PCC/KNO₃ shows potential as a viable alternative to MTA in vital pulp therapy, regardless of the adhesive strategy employed.