Comparison of two light guide tips used to photo-polymerize two dental composites. An in-vitro study

Abstract

INTRODUCTION : Manufacturer-made light guide (MMLG) tips of light emitting diodes (LEDs) are frequently damaged. Could custom-made light guide (CMLG) tips be suitable replacements? AIMS : 1.) To compare compressive fracture strengths of resin- based composite specimens photo-polymerized/ cured with a CMLG tip (acrylic-glass) and a MMLG tip (fibre-optic), used interchangeably on a poly-LED curing unit. 2.) To compare the costs of the CMLG tip and the MMLG tip. METHODS : Two groups of 20 composite cylindrical specimens (4 mm diameter, 4 mm length) were made in teflon moulds. Each light tip cured ten micro-hybrid Z100TM and ten nano-filled FiltekTM Supreme XTE specimens, (60 seconds each side). Storage was in distilled water at 37°C (±2°C) for 48 hours. Compressive strength testing (MPa) was done at a crosshead speed of 0.5 mm/min using a Bencor Multi-T device in an Instron machine. Student’s paired t-test and intra-class correlation coefficients (ICC) were applied for analysis and agreement testing. Relative costs of both light guide tips were determined and compared. RESULTS : Only the Z100TM groups showed significant differences in compressive fracture strength (p = 0.001). The CMLG tip was cheaper. DISCUSSION : The CMLG tip was preferred for photo-curing FiltekTM Supreme XTE resin based composite. The MMLG tip was preferred for photo-curing Z100TM resin based composite. CONCLUSION :​​​​ The CMLG was suitable for curing preclinical Z100TM and FiltekTM Supreme XTE resins and was substantially cheaper than the MMLG tip.