Human root dentin microhardness and degradation by triple antibiotic paste and calcium hydroxide.

PURPOSE: To investigate and compare the effects of the two widely used regenerative endodontics medicaments: Triple antibiotic paste (ciprofloxacine-metronidazole-clindamycin) and calcium hydroxide on the microhardness and degradation of human root dentin. METHODS: Following ethical approval and subject consent to use teeth in this research study, 60 singled-rooted permanent human teeth were randomly divided into six groups:(1) Tri-antibiotic paste with distilled water, or with (2) propylene glycol, (3) calcium hydroxide with distilled water, (4) calcium hydroxide propylene glycol, (5) untreated extracted teeth as negative controls, or (6) teeth instrumented and filled with calcium hydroxide or tri-antibiotic paste as positive controls. The microhardness tests were conducted after 1 and 2 months of exposure to the medicaments using a Vickers microhardness tester. Raman spectroscopy and energy dispersive x-ray spectroscopy were used to evaluate the chemistry and structure of the root dentin. RESULTS: There were differences in the dentin microhardness following treatment with the medicaments or controls (P< 0.05). The time of root dentin exposure to the medicaments was similar (P> 0.05). The root dentin microhardness was lower in the teeth treated with the triple antibiotic paste or calcium hydroxide when combined with propylene glycol. The root dentin collagen in these treated teeth were also significantly degraded when viewed with Raman spectroscopy and energy dispersive x-ray spectroscopy, whereas the inorganic phase (dentin) remained unaltered. Samples exposed to the antimicrobial agents with water as a vehicle exhibited stronger microhardness and less degradation. CLINICAL SIGNIFICANCE: These ex vivo results suggest that the triple antibiotic paste and calcium hydroxide should be used with propylene glycol if a fast diffusion is desired or with water to avoid degrading the collagen and weakening the microhardness of the teeth. Clinical trials are needed of new formulations of medicaments with propylene glycol to disinfect teeth for regenerative endodontic procedures, to help strengthen the teeth to prevent the loss of children's permanent immature teeth by fracture following caries or trauma.

Effect of an 8.0% arginine and calcium carbonate in-office desensitizing paste on the shear bond strength of composites to human dental enamel.

PURPOSE: To evaluate the effect of 8.0% arginine and calcium carbonate, in-office desensitizing paste (Colgate Sensitive Pro-Relief Desensitizing Paste) on the shear bond strength of composites to human dental enamel. METHODS: Two resin composites (Filtek Supreme, Premise) and human dental enamel were used. 16 samples per composite were prepared. Caries-free extracted human molars, not older than 3 months, and stored in distilled water were used for this portion of the experiment. Buccal and lingual surfaces were polished with high polishing pastes to create a uniform flat surface area to which the cylindrical composite samples were bonded. After polishing, the samples were rinsed in tap water and stored at 100% relative humidity. The resin composites were used to form cylindrical samples 3 mm x 1.6 mm, which were light-cured with a Demetron curing light according to the manufacturers' instructions. For each composite, 32 surfaces were used; 16 were a control group with the enamel polished with a water slurry of flour of pumice. The experimental group had the enamel polished with the 8.0% arginine and calcium carbonate desensitizing paste, using disposable latex free prophy cups with a slow speed hand piece at 3,000 rpm using moderate to light pressure, according to manufacturer's instructions. The composite cylinders were bonded to the enamel with their respective etching agents and adhesives and left in distilled water for 48 hours, after which the samples were sheared with an Instron testing machine at 0.5 mm/minute. After shearing, all samples were analyzed with a stereo microscope to evaluate failure pattern (failure at the enamel surface, failure at the composite surface, or mixed failure, at both enamel and composite surfaces). SEM images of selected surfaces were made to depict the overall morphology of the surface of dental materials used after 8.0% arginine and calcium carbonate desensitizing paste, application and shear strength tests. ANOVA and Student-Newman-Keuls tests (P < 0.05) were used to evaluate the difference among the groups. RESULTS: The 8.0% arginine and calcium carbonate desensitizing paste did not have a significant effect on the shear bond strength of the composites tested to enamel.

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).

Effect of APF Minute-Foam on the surface roughness, hardness, and micromorphology of high-viscosity glass ionomers.

PURPOSE: The purpose of the study was to evaluate the effect of Oral-B APF Minute-Foam on the surface roughness, hardness and morphology of high-viscosity glass-ionomer cements (GICs). METHODS: The GICs used were Fuji IX GP and Ketac-Molar. The controls were Vitremer resin-modified GIC and Fuji II conventional GIC. All materials were mixed to a restorative consistency. The encapsulated GICs were mixed with a Rotomix for 10 seconds. For each GIC, 14 specimens (6 mm in diameter and 3 mm thick) were made with a Teflon mold and a fresh mix for each sample. The specimens were allowed to set at room temperature for 15 minutes, and then stored in water at room temperature for 48 hours. Profilometry and microhardness measurements (Knoop) were obtained on the untreated specimens as baseline data. The specimens were then rinsed with water, gently air-dried and 1.23% APF Minute-Foam was applied for 1 minute with a brush, rinsed with water, gently air-dried, and hardness and roughness remeasured. In another set, similar measurements were obtained as before but after a 4 minute application of the APF foam. In a different set similar measurements were obtained as before but after a simulated 2-year application of the APF foam. The data were statistically analyzed using an ANOVA. The Student-Newman-Keuls method and Bonferroni tests (P=.05) were used for multiple comparisons of the means. The SEM was used to evaluate the APF effects on the surface micromorphology of the materials. RESULTS: Foam application time had no statistically significant effect on the surface roughness of Ketac-Molar and Vitremer. Fuji IX GP showed that 1 and 4 minute applications had lower values than after 2 years. Fuji II revealed similar roughness for the control at 1 and 4 minutes, but higher values after 2 years. Fuji IX GP proved no significant difference in hardness after the different application times. Ketac-Molar demonstrated less hardness than the control at 1 and 4 minutes but higher after 2 years. Foam application time had no statistically significant effect on the surface hardness of Vitremer. Fuji II showed 1 minute had harder values than 4 minutes and 2 years; the control was harder than 2 years. CONCLUSIONS: The SEM observations revealed that surface micromorphology was not significantly affected by the use of the Oral-B APF Minute-Foam. Treatment with the APF foam tested may be material dependent. It seems to be preferable to apply them for shorter times (1 minute versus 4 minutes) to reduce any adverse effect.

Effect of bleaching gels on the surface roughness, hardness, and micromorphology of composites.

This study sought to evaluate the effect of three bleaching gels on the surface roughness, hardness, and morphology of resin-based composites basically designed for posterior and anterior use. The application of the bleaching agents tested had no statistically significant effect on the surface roughness or hardness of the composites tested. With both unbleached and bleached samples, the posterior composite was significantly harder than the anterior composite while the roughness was not significantly different (p > 0.06).