Influence of Different Treatments on Light Transmission of Fiber Posts

Objectives: The aim of this study was to verify the effect of two different surface treatments on the light transmission of two glass-fiber post.
Methods: The sample was composed by 60 translucent glass-fiber posts from two manufacturers (White Post DC – WP and Superpost Light Core – SP, n=30/each). Specimens received one of the following surface treatments (n=10/condition): (A) no treatment (WT); (B) Silane (S); (C) 24% Hydrogen Peroxide (HP). They were evaluated in terms of (1) their light transmission at the coronal, middle and apical thirds, by a optical fiber coupled to a power meter (FieldMaster, Coherent, USA); and (2) total radiant power (mW), measured by an integrating sphere (Illumina 10, Labsphere, USA). Data assessment was done by generalized liner models/Bonferroni post-hoc test (α = 0.05).
Results: Light transmission (% radiant power) on each level (cervical, middle and apical) was significantly different for both posts. The coronal third presented the highest values (WP – WT: 74.8; S: 72.9; HP: 74.6; SP – WT: 73.6; S: 73.5; HP: 76.05), whereas the middle third had intermediate result (WP – WT: 20.7; S: 22.1; HP: 19.8; SP – WT: 20.8; S: 21,4; HP: 18.5) and the apical third had the lowest values (WP – WT: 4.6; S: 5.0; HP: 5.5; SP – WT: 5.5; S: 5.0; HP: 5.4). The total radiant power (mW) was significantly influenced by the posts and treatments tested, without interaction between factors. The mean estimates for light transmission was significantly lower for the treatment with hydrogen peroxide (HP: 11.6) than for the control condition (WT: 12.8), with intermediate results for the silane-treated posts (S: 12.2). Regardless of the treatment, WP (12.9) provided a significantly higher total radiant power than SP (11.4).
Conclusions: The percentage of transmitted radiant power decreases from the coronal to the apical third, regardless of the post. Both proprietary posts had slightly different potential to transmit light, which underwent mild reduction following surface treatments.