132 - Pediatric Interproximal Slot Preparation Depth of Cure Analysis via Microhardness and Photopolymerization Assays

Purpose:
The purpose of this study was to evaluate the efficacy of rapid curing lights in composite photopolymerization within pediatric slot preparations.

Methods:
Plastic discs of 7mm diameter(outer), 2.5mm height, 2.5mm diameter(inner)were milled. Tetric-PowerFill and UltraDent-Mosaic composites were acquired and placed on a flat, orange, glass slide. Composite was condensed completely into intaglio. Glass slide was placed on disc top. Ivoclar-Vivadent BluePhase light was placed into housing. Housing held light at distance of 0mm, 3mm, or 3mm-at-45º angulation. Composite cured at curing times(irradiance) as follows: 3s(3050mW/cm^2), 10s(1,200mW/cm^2), or 5s(2,000mW/cm^2) at distances and angles. After 24h, samples were tested using Vickers-Hardness-Test at 50gf with15s dwell. Three microhardness measurements on top-and-bottom surfaces were completed. Samples tested in batches of 10.


Results:
All groups showed lower bottom-to-top hardness ratio with increased composite-to-curing tip distance. Across tip-to-composite distances, UltraDentMosaic showed higher top-surface hardness vs TetricPowerFill. Across tip-to-composite distances (68-76VHN vs 40-51VHN), UltraDentMosaic showed the lowest bottom-surface hardness. Across all combinations, Irradiance and Energy Delivered(Time×Irradiance) trended with cure.

Conclusions:
1. Due to universally low bottom-to-top hardness ratio(0.20-0.66), we recommend composites be cured in increments less than 2.5mm to maximize cure completeness.
2. Due to TetricPowerFill’s increased top and bottom hardness when cured on the BluePhase 3s(3050mW/cm^2) mode when compared to 10s(1,200mW/cm^2), we recommend that it be cured the 3s-mode.
3. Due to decreased curing with increased tip-to-composite distance, we recommend that composites be cured at minimal distance.
4. The 3mm distance was similar to 3mm tip-to-composite distance-with-45º-angulation. We recommend users attempt to maintain light directness.