Effect of light irradiation distance during intermediate polymerization on depth of cure and hardness of indirect composite

Kota Okamura, DDS

Nihon University Graduate School of Dentistry

Purpose: This study evaluated the influence of distance between a halogen lamp and an indirect composite material surface on depth of cure and Knoop hardness number of the material.
Materials and Methods: An indirect composite material (Signum Ceramis DA2) and single-lamp intermediate light polymerization unit equipped with a 150 W halogen lamp (Sublite S) was assessed. Relative light intensity and temperature rise of the halogen lamp, depth of cure and Knoop hardness of the composite material were assessed with different lamp-material distances.
Results: Relative light intensity of the lamp, depth of cure and hardness of the material were maximal when the lamp-material distance was set as 20 mm. However, temperature rise during light exposure was apparent around the lamp aperture.
Conclusion: It can be concluded that the distance between the halogen lamp and the material to be polymerized should be set around 20 mm, when the composite material is polymerized with an intermediate polymerization unit equipped with the 150 W halogen lamp.
(Asian Pac J Dent 2014; 14: 7-12.)
Key Words: halogen lamp, indirect composite, intermediate polymerization, light intensity