LIGHT TRANSMISSION THROUGH POSTS TO SIMULATED REGIONAL ROOT CANAL USING DIFFERENT CURING SOURCES

Statement of problem: Light-activated luting agents have become an indispensable material for clinical dental use. However, it remains debatable as to which level, the light curing unit pro­vides sufficient intensity of light to achieve polymerization.
Purpose: The purpose of this study was to assess quantitatively the light intensity transmitted from three different light sources through translucent glass fiber posts with sequential cuts at depths of 15 mm, 10 mm, 5.0 mm
Materials and Methods: A 15 x 30 mm hollow Teflon ring was used. 60 specimens were prepared and assigned randomly into three groups (n=20 per each) according to the curing source. Within each group, 15 specimens were used for the experimental and 5 for the control group. For the experimental ones, a self-cure acrylic resin with black pigment was poured into the ring. A translucent glass fiber post was placed in the center of each ring and held in position till com­plete polymerization was occurred. For the control groups, the black resin blocks were filled with a lubricated dowel for its later removal. Therefore, the resin blocks with internal hollow orifices were obtained without the dowel. After preparing the blocks, readings for the passage of light will be made at the apical, middle , and cervical third level, involving dowel lengths of 15, 10, 5 mm respectively. A 40-second light exposure was used for each specimen and curing unit combina­tion .The output of light intensity was recorded. Mean light intensities were analyzed with 2-way ANOVA test followed by Kruskal-Wallis tests at α = 0.05.
Results: Two-way ANOVA results of light intensities for the experimental and control groups demonstrated significant differences between the light curing units (P<0.001) and the root level (P<0.001). Moreover, their interaction was also significantly different (P<0.001). For the experi­mental groups, Kruskal Wallis test revealed the highest quantity of light intensity was recorded for the high power LED curing unit at the cervical level of the root canal. For the control groups, the highest quantity of light intensity was displayed for the HPLED curing unit at the cervical level of the root canal.
Conclusions: The quantity of the light intensity transmitted from three different light sourc­es are significant different through translucent glass fiber posts with sequential cuts at depths of 15 mm, 10 mm , 5.0 mm