Toothbrush Abrasion Research Articles

Comparison of Profilometric and Microindentation Analyses for Determining the Impact of Saliva on the Abrasion of Initially Eroded Enamel

The aim of this in vitro study was to investigate the impact of saliva on the abrasion of eroded enamel using two measuring methods. A total of 80 bovine enamel specimens from 20 bovine incisors were allocated to four experimental groups (n = 20 specimens per group). After baseline surface microhardness (SMH) measurements and profilometry all specimens were subjected to erosion (2 min, 1% citric acid, pH: 3.6, 37°C). SMH was determined again, and the depths of the Knoop indentations were calculated. Thereafter, specimens were incubated in human saliva (group 1 – no incubation/control, group 2 – 0.5 h, group 3 – 1 h, group 4 – 2 h) before toothbrush abrasion was performed. After final SMH measurements and profilometry, indentations were remeasured, and surface loss was calculated. SMH did not return to baseline values regardless of the length of saliva incubation. Further, an irreversible substance loss was observed for all specimens. With the indentation method, significantly (p < 0.05) more substance loss was found for controls (least square means ± standard error of 198 ± 19 nm) than for groups 2–4 (110 ± 10, 114 ± 11, and 105 ± 14 nm). Profilometric assessment showed significantly more substance loss for controls (122 ± 8 nm) than for group 4 (106 ± 5 nm). Intraclass correlation for interrater reliability between measurement methods was low (0.21, CI: 0.1–0.3), indicating poor agreement. Exposure of eroded enamel to saliva for up to 2 h could not re-establish the original SMH. The amount of measured substance loss depended on the measurement method applied.

Efficacy of toothpastes in the prevention of erosive tooth wear in permanent and deciduous teeth

To evaluate the erosive preventive effect of toothpastes in permanent (PT) and deciduous teeth (dt). Enamel samples were divided into five groups (n= 20): G1: placebo toothpaste; G2: NaF toothpaste; G3: AmF-NaF-SnCl2 anti-erosion toothpaste; G4: SnF2-toothpaste; and G5: NaF anti-erosion toothpaste for children. The samples were exposed to five erosion-abrasion cycles (artificial saliva incubation; 3min in 1% citric acid; 2min in slurry, toothbrush abrasion, 50 strokes, 200g). Surface microhardness (SMH), surface specular reflection intensity (SRI), and cumulative surface loss (CSL) were measured. Comparisons among toothpastes were evaluated using Kruskal-Wallis tests and comparisons between PT and dt were evaluated using Wilcoxon's rank sum test. G1 exhibited significantly lower SMH values in PT than the other toothpastes (p< 0.05), with no significant differences among the others groups. In dt, G1 and G4 exhibited significantly different values than the other groups (p< 0.05). G4 exhibited lower values of SRI in both types of teeth. Deciduous teeth presented significantly higher SRI than PT (p< 0.05), except for G3. Deciduous teeth generally presented higher CSL than PT, except for G3. Deciduous teeth were more prone to mineral loss than permanent teeth. G5 exhibited better efficacy for both teeth, while G3 exhibited a better preventive effect only for deciduous teeth. Erosive tooth wear prevalence in children is growing and deciduous teeth are more susceptible than permanent teeth. Considering this, it is important to know the preventive effect of different toothpastes in an initial erosion-abrasion model.

Bond Stability of a Universal Adhesive System to Eroded/Abraded Dentin After Deproteinization.

Erosive/abrasive challenges can potentially compromise bonding to dentin. Aiming to improve the quality and stability of bonding to this substrate, this study investigated the combined effect of erosion and toothbrush abrasion on the microtensile bond strength (μTBS) stability to dentin using a universal adhesive system in total and self-etching modes, associated or not associated with deproteinization. Bovine dentin specimens were divided into five groups according to the organic matrix condition (n=20): control (C); erosion (E); erosion + abrasion (EA); erosion + sodium hypochlorite (EH); erosion + abrasion + sodium hypochlorite (EAH). The groups were further divided (n=10) according to the mode of application (total or self-etching) of a universal adhesive. After the bonding procedure, composite blocks were built up, and the samples were cut to obtain sticks for μTBS testing. For each specimen, one-half of the sticks was immediately tested, and the other one-half was tested after artificial aging (5000 thermocycles, 5°C and 55°C). Three-way analysis of variance (α=5%) showed a significant difference for the triple interaction ( p=0.0007). Higher μTBS means were obtained for the EH and EAH groups compared with the E and EA groups. The control group showed immediate μTBS values similar to that of the E and EA groups for both bond strategies. Erosion and erosion/abrasion did not significantly influence the immediate μTBS to dentin. Artificial aging reduced μTBS values for the groups C, E, and EA using the total-etching mode. Deproteinization maintained the bond stability to artificially aged eroded and eroded/abraded dentin.

Erosion-protecting effect of oral-care products available on the Swiss market. A pilot study

The present study sought to test oral-care products available on the Swiss market, such as toothpastes and gels, with respect to the protection of enamel against erosive tooth wear. A total of 56 enamel specimens were divided into 7 groups (n = 8): F-TP = Migros Budget Anti-Caries Toothpaste (Negative Control); F+Sn3500-TP = Elmex Erosion Protection Toothpaste (Positive Control); F-TP + F+Oligopep-Gel = Migros Budget Anti-Caries Toothpaste + Emofluor Protect Gel Professional; F+Sn3120-Gel = Emofluor Gel Intensive Care; F+Oligopep-TP = Candida Protect Professional Toothpaste; F+Sn1260-TP = Emoform-F Protect Toothpaste; and F+Sn3440-TP = Sensodyne Repair & Protect Toothpaste. The specimens were incubated in artificial saliva for 30 min and then brushed in a toothbrushing machine (10 s brushing; total 2 min exposure to the product). After the toothbrush abrasion, the specimens were rinsed, dried and submitted to an erosive challenge (2 min; 1% citric acid; pH 3.6). This sequence was repeated 4 times, and the total enamel surface loss was calculated using indentation measurements before and after the brushing period. All groups presented progressive surface loss throughout the experiment; after 4 cycles, total surface loss values ranged from 0.11 µm (F+Sn3120-Gel) to 0.89 µm (F+Sn1260-TP). Regarding the total surface loss values (median; interquartile range), F-TP (0.54; 0.42–0.59) presented no significant differences compared to any of the other groups. F+Sn3500-TP (0.33; 0.30–0.40), F-TP + F+Oligopep-Gel (0.34; 0.29–0.42) and F+Sn3120-Gel (0.11; 0.09–0.15) presented lower surface loss than F+Oligopep-TP (0.75; 0.59–0.98), F+Sn1260-TP (0.89; 0.68–1.13) and F+Sn3440-TP (0.69; 0.66–0.78). Conclusion: Although some of the oral-care products containing stannous ions or oligopeptide-104 presented numerically lower SL values, they did not present significantly better protection than a regular fluoride toothpaste. The gels showed a general trend of better enamel protection against ETW.

Erosion-protecting effect of oral-care products available on the Swiss market. A pilot study

The present study sought to test oral-care products available on the Swiss market, such as toothpastes and gels, with respect to the protection of enamel against erosive tooth wear. A total of 56 enamel specimens were divided into 7 groups (n = 8): F-TP = Migros Budget Anti-Caries Toothpaste (Negative Control); F+Sn3500-TP = Elmex Erosion Protection Toothpaste (Positive Control); F-TP + F+Oligopep-Gel = Migros Budget Anti-Caries Toothpaste + Emofluor Protect Gel Professional; F+Sn3120-Gel = Emofluor Gel Intensive Care; F+Oligopep-TP = Candida Protect Professional Toothpaste; F+Sn1260-TP = Emoform-F Protect Toothpaste; and F+Sn3440-TP = Sensodyne Repair & Protect Toothpaste. The specimens were incubated in artificial saliva for 30 min and then brushed in a toothbrushing machine (10 s brushing; total 2 min exposure to the product). After the toothbrush abrasion, the specimens were rinsed, dried and submitted to an erosive challenge (2 min; 1% citric acid; pH 3.6). This sequence was repeated 4 times, and the total enamel surface loss was calculated using indentation measurements before and after the brushing period. All groups presented progressive surface loss throughout the experiment; after 4 cycles, total surface loss values ranged from 0.11 µm (F+Sn3120-Gel) to 0.89 µm (F+Sn1260-TP). Regarding the total surface loss values (median; interquartile range), F-TP (0.54; 0.42–0.59) presented no significant differences compared to any of the other groups. F+Sn3500-TP (0.33; 0.30–0.40), F-TP + F+Oligopep-Gel (0.34; 0.29–0.42) and F+Sn3120-Gel (0.11; 0.09–0.15) presented lower surface loss than F+Oligopep-TP (0.75; 0.59–0.98), F+Sn1260-TP (0.89; 0.68–1.13) and F+Sn3440-TP (0.69; 0.66–0.78). Conclusion: Although some of the oral-care products containing stannous ions or oligopeptide-104 presented numerically lower SL values, they did not present significantly better protection than a regular fluoride toothpaste. The gels showed a general trend of better enamel protection against ETW.

Impact of Gastric Acid Induced Surface Changes on Mechanical Behavior and Optical Characteristics of Dental Ceramics.

To test the impact of exposure to artificial gastric acid combined with toothbrush abrasion on the properties of dental ceramics. Earlier research has indicated that immersion in artificial gastric acid has caused increased surface roughness of dental ceramics; however, the combined effects of acid immersion and toothbrush abrasion and the impact of increased surface roughness on mechanical strength and optical properties have not been studied. Three commercially available ceramics were chosen for this study: feldspathic porcelain, lithium disilicate glass-ceramic, and monolithic zirconium oxide. The specimens (10 × 1 mm discs) were cut, thermally treated as required, and polished. Each material was divided into four groups (n = 8 per group): control (no exposure), acid only, brush only, acid + brush. The specimens were immersed in artificial gastric acid (50 ml of 0.2% [w/v] sodium chloride in 0.7% [v/v] hydrochloric acid mixed with 0.16 g of pepsin powder, pH = 2) for 2 minutes and rinsed with deionized water for 2 minutes. The procedure was repeated 6 times/day × 9 days, and specimens were stored in deionized water at 37°C. Toothbrush abrasion was performed using an ISO/ADA design brushing machine for 100 cycles/day × 9 days. The acid + brush group received both treatments. Specimens were examined under SEM and an optical microscope for morphological changes. Color and translucency were measured using spectrophotometer CIELAB coordinates (L*, a*, b*). Surface gloss was measured using a gloss meter. Surface roughness was measured using a stylus profilometer. Biaxial flexural strength was measured using a mechanical testing machine. The data were analyzed by one-way ANOVA followed by Tukey's HSD post hoc test (p < 0.05). Statistically significant changes were found for color, gloss, and surface roughness for porcelain and e.max specimens. No statistically significant changes were found for any properties of zirconia specimens. The acid treatment affected the surface roughness, color, and gloss of porcelain and e.max ceramics. The changes in translucency and mechanical strength for all materials were not statistically significant. Zirconia ceramic showed resistance to all treatments.

Effect of simulating tooth brushing on surface change of different ceramic materials

Objectives: Purpose of the present study was to evaluate the surface roughness of current ceramics before and after tooth brushing abrasion, using simulated tooth brushing wear testing. Materials and Methods: 40 ceramic samples (Zirconia ceramics, Vita Enamic, Lava Ultimate, & E-max ceramics) were cut from corresponding 4 types of ceramic blocks using microtome, then 40 samples were divided into 4 groups (n=10). Each sample has a fixed dimension about 10 x 10 x 2mm (thickness). The 3-body simulated tooth brushing wear testing was performed using a programmable logic controlled equipment; ROBOTA chewing simulator* integrated with thermo-cyclic protocol, then Surface roughness of each material (Ra) was measured with USB digital surface profile gauge. Results: Total effect of material; regardless to toothbrush wear simulation cycles, totally there was no-significant (p=0.1379 > 0.05) difference between all materials where (Zr ≥ e.max ≥V enamic ≥ L ultimate) with their mean values respectively after 24 months (Zr; 0.25898 ±0.0035, e.max; 0.25428 ±0.0029, V enamic; 0.25413 ±0.0049, L ultimate; 0.25403 ±0.0028). Total effect of toothbrush wear simulation cycles; irrespective of material, totally toothbrush wear simulation cycles did not affect roughness significantly (p=0.8281 > 0.05) difference between all materials where (18 m ≥ baseline ≥ 6 m ≥24 m ≥ 12 m). Conclusions: Brushing of ceramic materials with conventional dentifrices non-significantly increased surface roughness, where results of surface roughness present within the clinically acceptable range, not insult the patient intraorally.

Biological and mechanical degradation affecting the surface properties of aesthetic restorative

Aim: To evaluate the roughness (Ra), Knoop hardness (KHN) and change of color (∆E) of esthetic restorative materials (Filtek Z350-composite nanoparticle; Empress Direct-composite nanohybrid and IPS e.Max-ceramic) subjected to contact with the Streptococcus mutans biofilm (biological degradation) associated with abrasion generated by tooth brushing (mechanical degradation). Methods: Ten specimens of each material were prepared, and the surface properties initial were evaluated. All specimens were exposed to Streptococcus mutans inoculum; after 7 days, surface properties were evaluated. The specimens were submitted to a 30,000 toothbrushing cycles, using a toothpaste slurry, then, surface properties were evaluated again. Data were analyzed by Proc-Mixed, One-way ANOVA, Tukey-Kramer and Tukey’s tests (α = 0.05). Results: At the baseline, ceramic showed the highest Ra and KHN values; after the biological degradation the composites showed increased Ra, but KHN did not change; after the mechanical degradation, Empress showed decreased Ra and Z350 showed similar Ra, the KHN increased to both composites, and all materials had increased lightness after the mechanical degradation. Conclusions: The results suggest that, when exposed to Streptococcus mutans biofilm and toothbrush abrasion, the ceramics undergoes minimal degradation and the composites exhibited variable degradation, depending on the composition of the material.

Monomer conversion, dimensional stability, strength, modulus, surface apatite precipitation and wear of novel, reactive calcium phosphate and polylysine-containing dental composites.

PurposeThe aim was to assess monomer conversion, dimensional stability, flexural strength / modulus, surface apatite precipitation and wear of mono / tri calcium phosphate (CaP) and polylysine (PLS)—containing dental composites. These were formulated using a new, high molecular weight, fluid monomer phase that requires no polymerisation activator.Materials and methodsUrethane and Polypropylene Glycol Dimethacrylates were combined with low levels of an adhesion promoting monomer and a light activated initiator. This liquid was mixed with a hybrid glass containing either 10 wt% CaP and 1 wt% PLS (F1) or 20 wt% CaP and 2 wt% PLS (F2). Powder to liquid mass ratio was 5:1. Commercial controls included Gradia Direct Posterior (GD) and Filtek Z250 (FZ). Monomer conversion and polymerisation shrinkage were calculated using Fourier Transform Infrared (FTIR). Subsequent volume increases in water over 7 weeks were determined using gravimetric studies. Biaxial flexural strength (BFS) / modulus (BFM) reduction and surface apatite precipitation upon 1 and 4 weeks immersion in water versus simulated body fluid (SBF) were assessed using a mechanical testing frame and scanning electron microscope (SEM). Mass / volume loss and surface roughness (Ra) following 7 weeks water immersion and subsequent accelerated tooth-brush abrasion were examined using gravimetric studies and profilometer.ResultsF1 and F2 exhibited much higher monomer conversion (72%) than FZ (54%) and low calculated polymerization shrinkage (2.2 vol%). Final hygroscopic expansions decreased in the order; F2 (3.5 vol%) > F1 (1.8 vol%) ~ Z250 (1.6 vol%) > Gradia (1.0 vol%). BFS and BFM were unaffected by storage medium type. Average BFS / BFM upon 4 weeks immersion reduced from 144 MPa / 8 GPa to 107 MPa / 5 GPa for F1 and 105 MPa / 6 GPa to 82 MPa / 4 GPa for F2. Much of this change was observed in the first week of immersion when water sorption rate was high. Surface apatite layers were incomplete at 1 week, but around 2 and 15 micron thick for F1 and F2 respectively following 4 weeks in SBF. Mass and volume loss following wear were equal. Average results for F1 (0.5%), F2 (0.7%), and FZ (0.5%) were comparable but lower than that of GD (1%). Ra, however, decreased in the order; F1 (15 μm) > F2 (11 μm) > GD (9 μm) > FZ (5 μm).ConclusionsHigh monomer conversion in combination with large monomer size and lack of amine activator should improve cytocompatibility of the new composites. High monomer molecular weight and powder content enables low polymerisation shrinkage despite high conversion. Increasing active filler provides enhanced swelling to balance shrinkage, which, in combination with greater surface apatite precipitation, may help seal gaps and reduce bacterial microleakage. High monomer conversion also ensures competitive mechanical / wear characteristics despite enhanced water sorption. Furthermore, increased active filler could help reduce surface roughness upon wear.

Antibiofilm properties of model composites containing quaternary ammonium methacrylates after surface texture modification

ObjectiveInvestigate antimicrobial properties and surface texture of model composites with different concentration and alkyl chain length of quaternary ammonium monomers (QAS). MethodsMonomers derived from QAS salts with alkyl chain lengths of 12 carbons ((dimethylaminododecyl methacrylate) DMADDM) and 16 carbons (dimethylaminohexadecyl methacrylate—DMAHDM) were obtained from the reactions of their respective organo-halides with the tertiary amine 2-(dimethylamino)ethyl methacrylate (DMAEMA). DMADDM and DMAHDM were incorporated into model composite in concentrations of 5 or 10%, resulting the following groups: G12.5 (DMADDM 5%), G12.10 (DMADDM 10%), G16.5 (DMAHDM 5%), G16.10 (DMAHDM 10%) and GC (control). Biofilm viability, lactic acid production and surface roughness were analysed 24h after samples preparation (initial), repeated after toothbrush abrasion and after polishing simulation. Data were submitted to ANOVA and Tukey’s test (p≤0.05). ResultsThe longer the molecular chain size of QAS and the higher its concentration (G16.10), the lower was the viability and the production of lactic acid by the biofilm. No differences were detected in initial roughness’ measurements among groups. However, after abrasion, there was an increase of biofilm viability and lactic acid production. Composites containing QAS presented rougher surfaces compared to the CG. After polishing, biofilm viability and surface roughness were statistically similar for all groups. Nevertheless, DMAHDM at 10% showed reduction in lactic acid production. SignificanceChain length and concentration of QAS influenced biofilm development and production of lactic acid. Longer chains and higher concentrations of QAS promoted better antimicrobial properties. Changes in surface texture caused by abrasion, decreased antibiofilm properties.

Non-carious cervical lesions imaged by focus variation microscopy

ObjectiveThe aim of this study is to characterize the morphological and histological features of NCCLs in a group of extracted teeth using a focus variation optical microscopic technique that is capable of detecting minute variation in surface topography. MethodsTwenty three extracted teeth containing NCCLs were collected. Histological features of the surface and longitudinal cross sections were examined using a focus variation microscope (FVM). ResultsThe sample included 8 teeth with wedge-shaped lesions; the remaining 15 contained saucer-shaped lesions. Wedge-shaped lesions showed obliterated dentinal tubules, parallel furrows and micro-fractures in the surface; longitudinal cross sections revealed subsurface micro-fractures extending toward the pulp chamber. The surfaces of typical saucer-shaped lesions were smooth and relatively featureless. ConclusionsFVM imaging shows microstructures that are consistent with simultaneous erosion and toothbrush abrasion. Saucer shaped lesions have a smooth featureless surface as well as craters and dimples that could be attributed to uneven acid attack. In wedge-shaped lesions, the presence of scratches and furrows could be attributed to mechanical forces such as tooth brush abrasion. The furrows and in-surface micro-factures of wedge shaped lesions suggest a possible role of tensile stresses but require further investigation. Clinical significanceNCCLs present in two morphologies, either saucer-shaped or wedge-shaped. Erosion and toothbrush abrasion are important in both types of lesions. Tensile stresses due to occlusal loading may be important in some wedge-shaped lesions. Knowing the etiology of cervical lesions is the key for their prevention.

EFFECT OF TOOTHBRUSH ABRASION ON SURFACE ROUGHNESS OF DEMINERALIZED ENAMEL TREATED WITH RESIN INFILTRATION

This study was conducted to evaluate the effect of the toothbrush abrasion on surface roughness of the demineralized enamel treated with resin infiltration. Materials and methods: A total number of 12 extracted caries-free human permanent premolars were used in this study. Surface roughness assessment of specimens (sound enamel) was performed using Environmental Scanning Electron Microscope (R1). Specimens were subjected to a demineralization protocol until a white spot lesion (WSL) was developed (chalky white lesion) (surface roughness R2). Resin infiltrant was applied on the WSL (R3), followed by tooth brush abrasion(R4). Surface roughness assessment of specimens (R) was performed qualitatively and quantitatively using Environmental Scanning Electron Microscope for each of the four stages of the study. Results: One-way ANOVA showed statistical significant difference between the tested groups (P= 0.001). The post-hoc test revealed that sound enamel has significantly the lowest surface roughness than all other tested groups (P= 0.001). Moreover, demineralized enamel and toothbrush abraded resin infiltrated enamel had significantly lower surface roughness than that of resin infiltrated enamel (P= 0.001). No significant differences were revealed between demineralized enamel and toothbrush abraded resin infiltrated enamel (P= 0.309). Conclusions: Within the limitations of the study, it can be concluded that: 1- Surface roughness of enamel with artificial carious lesion treated with resin infiltration was higher than that of sound enamel. 2- Tooth brushing have the potential to lower the surface roughness of artificial carious lesion treated with resin infiltration.

Abrasion: A Common Dental Problem Revisited.

Dental abrasion is most commonly seen at the cervical necks of teeth, but can occur in any area, even inter-dentally from vigorous and incorrect use of dental floss. Acid erosion has been implicated in the initiation and progress of the cervical lesion, while tooth-brush abrasion has long been held as the prime cause of cervical abrasion. Identification of the risk factors is clearly important in order to modify any habits and provide appropriate advice.

Effects of tooth-brushing force with a desensitising dentifrice on dentine tubule patency and surface roughness

ObjectivesTo investigate the effects of a 5% NovaMin containing dentifrice on dentine tubule patency and surface roughness at 100g and 400g tooth brush abrasion forces. Methods75 polished human dentine samples were prepared and randomly allocated into one of five groups; control (1), Na2PFO3 100g abrasion force (2), NovaMin 100g (3), Na2PFO3 400g (4) and NovaMin 400g (5). The control group underwent two 2-min cycles of artificial saliva (AS), one 2-min erosion cycle; the rest underwent two toothbrush abrasion cycles in an AS/dentifrice slurry and one 2-min erosion cycle. All samples were imaged at baseline and post intervention using Tandem Scanning Microscopy and Profilometry to analyse tubule patency and roughness. ResultsMean tubule patency increased significantly between baseline and post intervention in groups 1,2 and 4 and decreased significantly post intervention in groups 3 and 5 (p<0.01). Post intervention, there were statistically significant differences in mean patent tubules between NovaMin and the Na2PFO3 and control groups (p<0.001). Surface roughness increased for all groups between baseline and post interventions (P<0.001); mean (SD) roughness increases for groups 1, 2, 3, 4 and 5 were 0.14 (0.05) μm, 0.18 (0.04) μm, 0.16 (0.06) μm, 0.19 (0.07) μm and 0.21 (0.02) μm respectively. Differences between group 1 and 5 were significant (p<0.01). ConclusionsBrushing with NovaMin resulted in significant dentine tubule occlusion at 100g and 400g, but brushing with Na2PFO3 resulted in increased tubule patency. Surface roughness increased significantly at 400g brushing with NovaMin. There was no correlation between tubule patency and surface roughness. Clinical significanceA NovaMin desensitising dentifrice resulted in tubule occlusion even at high brushing forces. There was minimal increase in surface roughness at the lower (100g) brushing force.

Evaluation of gloss retention of indirect composite after toothbrush abrasion

Evaluation of gloss retention of indirect composite after toothbrush abrasion

Evaluation of Surface Microhardness and Abrasion Resistance of Two Dental Glass Ionomer Cement Materials after Radiant Heat Treatment

The aim of this study was to evaluate the effect of a radiant heat treatment using a dental LED unit on the surface microhardness and abrasion resistance after toothbrushing simulation of two conventional GIC materials. Two conventional GIC materials were studied in this investigation: Ketac Fil Plus Aplicap and IonoStar Molar. Twenty disk-shaped specimens (n=10) were prepared of each GIC (7 mm × 2 mm) using cylindrical Teflon molds. Group 1 specimens were left in the mold to set without any treatment, while in Group 2 after placement in the mold the specimens were irradiated for 60 sec at the top surface using a LED light-curing unit. Toothbrushing simulation was carried out using a commercial electric toothbrush which was fixed in a constructed device that allowed the heads of the brushes to be aligned parallel to the surface of the specimens and to control the pressure, with the following parameters: load of the toothbrush standardized at 250 g, medium hardness toothbrush head, and rotation sense changing every 30 sec. The toothbrush abrasion test mechanism, based on a 1.25-Hz frequency for 10,000 cycles, was equivalent to 800 days (~2 years) of brushing. Surface hardness, surface roughness, and surface loss after abrasive procedure were evaluated using Vickers method and Vertical Scanning Interferometry. Data were statistically analyzed using one-way ANOVA and Tukey’s post hoc test (a=0.05). The radiant heat treatment increased the surface microhardness and decreased surface roughness and surface loss after abrasive procedures of both the tested GIC materials but to different extent. Between the tested GIC materials there were significant differences in their tested properties (p&lt;0.05).

Timing of dietary acid intake and erosive tooth wear: A case-control study

ObjectivesThere is a lack of clinical data on the impact of timing of dietary acid intake and toothbrush abrasion when attempting to control erosive tooth wear progression. The aim of this study was to estimate the association of theoretical causative factors with erosive tooth wear to inform evidence-based guidelines. MethodsUsing case-control study design, 300 participants with dietary erosive tooth wear and 300 age-matched controls were recruited from the restorative clinics of King’s College London Dental Institute. A previously validated questionnaire was adapted to be interviewer-led and to assess frequency, timing and duration of dietary acid intake in addition to alternate drinking habits prior to swallowing. Timing of toothbrushing in relation to meals and dietary acid intake was investigated. Associations with erosive tooth wear were assessed in crude and adjusted logistic regression models. ResultsFruit intake between meals (p<0.001), but not with meals (p=0.206), was associated with erosive tooth wear and contrasted with acidic drinks which maintained a strong association regardless of timing of intake (OR up to 11.84 [95% CI: 5.42–25.89], p<0.001). Prolonged fruit eating and alternate drinking habits prior to swallowing (OR 12.82 [95% CI: 5.85–28.08] and 10.34 [95% CI: 4.85–22.06] respectively) were as strongly associated with erosive tooth wear as three or greater daily acid intakes (OR 10.92 [95% CI: 4.40–27.10]). Toothbrushing within 10min of acid intake was not associated with erosive tooth wear following adjustments for dietary factors (OR 1.41 [95% CI: 0.82–2.42], p=0.215]). ConclusionSignificantly increased odds ratios were observed when acids were consumed between meals in this cohort of patients. Universal advice to delay brushing after meals may not be substantiated. Clinical significancePrevention should be focused on avoiding dietary acids between meals, eliminating habits which increase contact time with the acid and reducing daily intake of acidic drinks. Toothbrushing after meals was not associated with erosive wear. Toothbrushing immediately after an acid challenge requires further investigation.

Influence of Finishing and Polishing Techniques and Abrasion on Transmittance and Roughness of Composite Resins.

The aim of this study was to evaluate the influence of finishing and polishing systems and toothbrush abrasion on transmittance (T) and surface roughness (Ra) of three composite resins (Filtek Z350 XT, Tetric N-Ceram, and IPS Empress Direct). Eighteen resin disks (10 mm diameter × 2 mm thick) finished by polyester strips had initial surface smoothness recorded, representing phase 1 (P1). Specimens were divided into three groups (n=6) according to the finishing/polishing instrument used (OneGloss, TopGloss, and Sof-Lex) to compose phase 2 samples (P2). Then specimens were subjected to 514 cycles of toothbrush simulation using a toothpaste slurry, with a constant load applied to soft bristles, and were then washed (phase 3=P3). After each phase, the specimens were examined by an optical profiler and spectrophotometer to measure Ra and T. Data were analyzed by analysis of variance, Tukey and Pearson tests. T values were statistically influenced by composite resin ( p=0.000) and phase of measurement ( p=0.000) factors, while the finishing/polishing system used ( p=0.741) did not affect T. On the other hand, Ra values were statistically affected by the factor finishing/polishing system ( p=0.000), but not by composite resin ( p=0.100) and phase of measurement ( p=0.451). Tetric N-Ceram and Empress Direct presented higher values of roughness when polished by OneGloss, while TopGloss and Sof-Lex showed a lower roughness. It can be concluded that composite resins transmitted more light after dental abrasion. Transmittance of composite resins was not modified by the distinct roughness created by finishing/polishing instruments.

Three-dimensional invitro measurements of tooth wear using fluoridated dentifrices.

The aim of this study was to compare differences in wear of human enamel and dentine invitro using a 3D measurement method comparing silica versus non-silica containing fluoridated dentifrices (Colgate Total(™) [CT] or Fluor Protector Gel(™) [FPG]). Mounted native enamel (n = 36) and polished dentine (n = 36) samples were subjected to 10 wear cycles. Each cycle consisted of: (1) 1 hour remineralization in artificial saliva (AS); (2) 10 minute erosion (0.3% citric acid; pH = 2.8); (3) 2 minute toothbrush abrasion in AS (G1, control) or a slurry of 3:1 by weight of AS:dentifrice (G2 = CT; G3 = FPG) under a load of 2 N. Each group contained 12 enamel and 12 dentine samples. Paired pre- and post-wear scans made with a contacting scanner were digitally superimposed using ball bearings as datum. Mean and (SD) enamel wear was G1 = 21.9 μm (6.4); G2 = 15.2 μm (2.8); G3 = 16.9 μm (3.2). Enamel wear was not different between dentifrices (p = 0.99). Both dentifrices resulted in less enamel wear compared to the control (p < 0.05). Dentine wear was G1 = 41.3 μm (8.1); G2 = 29.1 μm (4.4); G3 = 22.1 μm (3.5). Differences in measurements were observed between dentifrices and control (p < 0.05) and between dentifrices (p = 0.014) with FPG showing less dentine wear than CT. FPG offered protection against erosive/abrasive tooth wear in dentine compared to CT. FPG did not offer such protective effect on enamel wear.

Toothbrushing abrasion susceptibility of enamel and dentin bleached with calcium-supplemented hydrogen peroxide gel

The objective of this study was to evaluate enamel and dentin susceptibility to toothbrushing abrasion, after bleaching with 7.5% hydrogen peroxide (HP) gel supplemented or not with 0.5% calcium gluconate (Ca). Toothbrushing was performed immediately and 1h after bleaching, with two suspensions (high and low abrasivity). Bovine enamel and dentin specimens were divided into 12 groups (n=10) according to the bleaching gel (with and without Ca), slurry abrasivity (high or low) and elapsed time after bleaching (immediately and after 1h). As control, a group was not bleached, but abraded. The treatment cycle (7 d) consisted of bleaching (1h) and toothbrushing (135 strokes/day) immediatelly or after 1h of artificial saliva exposure. Surface roughness and surface loss (μm) were measured by profilometry and analysed by three-way ANOVA (5%). Surface roughness means were significantly influenced by slurry abrasivity (p<0.0001). For enamel loss, significant triple interaction was observed (p<0.0001). HP-bleached groups and immediately brushed with high-abrasive slurry exhibited increased loss (1.41±0.14) compared to other groups (μm). Control and HP+Ca-bleached groups brushed after 1h with low abrasive slurry presented the lowest loss (0.21±0.03/0.27±0.02). For dentin loss, significant interaction was observed for bleaching and interval factors (p<0.001). 7.5%HP-bleached groups and immediately brushed showed significantly higher loss (8.71±2.45) than the other groups. It was concluded that surface roughness increased when high abrasive was used, independently of bleaching. 7.5%HP increased enamel and dentin loss, mainly with high abrasive slurries. Calcium supplementation of bleaching gel reduced surface loss. Additionally, in order to minimize tooth wear susceptibility, it is recommended to delay brushing after bleaching. Clinical relevanceAfter bleaching gel application, postponing toothbrushing is recommended, as well as brushing with low abrasive dentifrices. Additionally, supplementation of hydrogen peroxide gel with calcium-based remineralizing agent potentially reduces tooth loss after abrasion.