Effect of a desensitizing paste containing 8% arginine and calcium carbonate on the surface roughness of dental materials and human dental enamel.

Purpose: To evaluate the effect of an 8% arginine-calcium carbonate fluoride-free desensitizing paste on the surface roughness of resin composite, porcelain, amalgam, gold, and human dental enamel both prior to and following simulated toothbrushing.

Methods: A resin composite (Filtek Supreme), a commercial porcelain (IPS Empress), an amalgam (Dispersalloy), gold (JIF-PF) and human dental enamel were used, as well as commercial finishing and polishing instruments. Eight two-sided samples were fabricated for each group. The composite and amalgam samples were stored at 100% relative humidity and 37 degrees C for 48 hours prior to measuring the surface roughness and completing the subsequent finishing and polishing procedures. Enamel blocks were cut from human lesion-free teeth and embedded in acrylic. The blocks were then polished flat with high polishing pastes. For gold and porcelain, the same size was used and the materials processed by a professional dental laboratory. Following storage, each surface was polished using the Super-Snap (Shofu) system. The amalgam was polished with conventional polishing techniques. Roughness (Ra and Ry) was evaluated with both a 3D non-contact profilometer and a stylus profilometer. With the two-sided samples only one side was polished with the desensitizing paste and the other side was left unpolished without paste. The 8% arginine-calcium carbonate desensitizing paste was applied to a surface for 15 seconds using a single disposable prophy cup. Each polished surface was measured by the profilometers and three roughness values per surface were recorded as the "initial prophy" surface. Following initial surface analysis, each side of every sample was treated with a simulated toothbrushing technique using a toothbrushing device (V-8). A 50:50 (w/w) slurry of toothpaste (Colgate Cavity Protection) and deionized water was used. Each surface was brushed 10,000 times. Then, the samples were rinsed with tap water and stored in 100% humidity until roughness values were obtained using the profilometers as previously described ("toothbrush surface"). After analyzing the brushed surfaces, the samples were returned to their original treatment group ("desensitizing paste"). Each surface was re-polished with the desensitizing paste as previously stated. Those surfaces (referred to as "recall paste") were measured as previously described for final surface roughness. Data was analyzed using repeated measures two-factor ANOVA with Tukey HSD pairwise comparison as appropriate (alpha=0.05). Two additional samples were made of each material in order to measure step-heights. Tape was placed on the surface of each sample to separate the treatment side and the non-treated side. The tape was removed before each profilometry reading.

Results: The desensitizing paste containing 8% arginine and calcium carbonate did not have a significant effect on the surface roughness of the substrates tested. Although the 3D non-contact profilometry images showed slight roughness after toothbrushing followed by the use of the desensitizing paste, these changes were not statistically significant (P>0.05).