3D-Image analysis of the impact of toothpaste abrasivity on the progression of simulated non-carious cervical lesions.

OBJECTIVES: To investigate the effect of toothpaste abrasive level on the progression of non-carious cervical lesions (NCCLs) using 3D-image subtraction. METHODS: Upper first premolars were allocated into seven groups (n = 16) of toothpaste/abrasive slurries: A-Zeodent113/5%, B-Zeodent124/10%, C-Zeodent103/15%, D-Sensodyne Pronamel, E-Crest Cavity-Protection, F-Crest Pro-Health-Whitening, and G-Deionized water (DIW). Teeth were mounted on acrylic blocks, and their root surfaces covered with acrylic resin, except for 2-mm near the cemento-enamel junction that was exposed to toothbrushing. Specimens were brushed with the slurries for 5000-, 15,000-, 35,000- and 65,000-strokes. Impressions were taken at baseline and after each brushing time, and then scanned by a 3D optical profilometer. Dentine volume loss was calculated by image subtraction software and subjected to mixed-model ANOVA and multiple comparison tests (α = 0.05). RESULTS: No significant differences among slurries were observed at 5000 and 15,000. At 35,000, F showed higher loss than all other groups except C, which did not differ from the others. At 65,000, F (4.19 ±â€¯3.29 mm3) showed the highest loss, followed by C (2.33 ±â€¯1.47 mm3), which differed from all the other groups except B (1.85 ±â€¯0.91 mm3). Groups B, A (1.35 ±â€¯0.65 mm3), D (1.17 ±â€¯0.48 mm3), E (1.40 ±â€¯0.68 mm3) and G (1.12 ±â€¯0.73 mm3) did not differ from each other. Groups F and C showed significant increase of volume loss starting at 35,000, while B, A, D and E only at 65,000; no increase loss was observed for G. CONCLUSIONS: 3D-image subtraction was able to quantify and differentiate tooth loss, but only at advanced stages. The progression of NCCLs was more evident and faster for highly abrasive slurries. CLINICAL SIGNIFICANCE: Upon root dentin exposure, brushing with lower abrasive dentifrices is advisable to reduce the risk for NCCLs development.

Efficacy of different strategies to treat root dentin eroded by liquid or gaseous hydrochloric acid associated with brushing abrasion.

OBJECTIVE: This study aims to evaluate how casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) associated with Nd:YAG or Diode laser affects dentin exposed to hydrochloric acid (HCl) with or without tooth brushing. DESIGN: One hundred and sixty human root dentin blocks were selected after they were initially eroded with liquid HCl (pH 1.2) 3x for one day. The blocks were divided into the following groups: G1- liquid HCl (HCl-l), G2- HCl-l + brushing, G3- gaseous HCl (HCl-g), and G4- HCl-g + brushing. Each group was randomly assigned to the following treatments (n = 10): A) Control (no treatment), B) CPP-ACP, C) CPP-ACP associated with Nd:YAG laser (λ = 1064 nm) (40 mJ, 10 Hz, 0.4 W, 15 s), and D) CPP-ACP associated with Diode laser (λ = 980 nm) (0.5 W, 200 µs, 15 s). The treatment with CPP-ACP (G2, G3 and G4) was applied on the dentine surface for 5 min. Erosion (6x/day/20 s) and erosion (6x/day/20 s) with abrasion (2x/10 s) were performed for five days. Dentin volume loss was determined by 3D confocal laser microscopy. Data were analyzed with two-way ANOVA and Tukey's tests. RESULTS: G1 - CPP-ACP (10.77 ±â€¯1.66) and CPP-ACP associated with Diode laser (9.98 ±â€¯0.89) showed lower volume loss in relation Control group (12.86 ±â€¯0.63) (p < 0.05). G2 - CPP-ACP associated with Diode laser (12.41 ±â€¯1.08) elicited lower volume loss as compared to the Control (14.42 ±â€¯1.24) (p < 0.05). As for G3 and G4, all treatments showed similar volume loss. CONCLUSION: CPP-ACP and CPP-ACP associated with Diode laser could control dental tissue loss in dentin eroded by liquid HCl. Moreover, CPP-ACP associated with Diode laser could effectively decrease dental tissue loss in dentin exposed to liquid HCl and brushing.

TiF4 gel effects on tubular occlusion of eroded/abraded human dentin.

This in situ study evaluated the tubular occlusion caused by 4% TiF4 gel on the surface of eroded/abraded dentin. Sixty human dentin samples were eroded in vitro and assigned into six groups (n = 10) according to the in situ surface treatment and number of cycling days: 4% TiF4 gel applied once (TiF4 1), twice (TiF4 2), or three times (TiF4 3) followed by 2, 4, and 6 days of erosive/abrasive in situ cycling, respectively. Control groups (no treatment) were subjected to 2 (C1), 4 (C2), and 6 (C3) days of erosive/abrasive in situ cycling only. A seventh group (n = 10) was comprised by in vitro uneroded samples (UN), subjected to 6 days of in situ erosive/abrasive cycling. Each cycling day consisted on six erosive (0.5% citric acid, pH 2.6) and one abrasive events. Environmental scanning electron microscopy micrographs were taken. For all groups, blinded examiners assessed dentin tubules occlusion using visual scores (0-unoccluded, 1-partially occluded by granular deposits, 2-partially occluded by reduction in tubular lumen into diamond shape, 3-completely occluded) on images captured prior and after the in situ phase. Scheirer-Ray-Hare test demonstrated that treatments significantly affected tubule occlusion (p < .001). Dunn's test showed that tubule occlusion in TiF4 3 was significantly higher than in C1. Tubule occlusion in remaining groups did not differ from that observed in groups TiF4 3 and C1. Tubule occlusion was significantly higher after in situ phase. It may be suggested that TiF4 , when applied three times, was able to positively change tubule occlusion of dentin samples.

A randomised exploratory clinical evaluation of dentifrices used as controls in dentinal hypersensitivity studies.

OBJECTIVES: To explore relative efficacy of six negative-control dentifrices utilised as controls in clinical studies compared with two dentine hypersensitivity (DH)-relief dentifrices used 2×/day for 8 weeks. METHODS: Six control dentifrices differing in terms of fluoride source (sodium fluoride/sodium monofluorophosphate), abrasive base (silica/dicalcium phosphate), relative dentine abrasivity (RDA) (∼17 to ∼180) and colour (white/blue/multicoloured stripes) were compared with a depolarising dentifrice (5% KNO3; RDA ∼70-97; 'Test 1') and an occlusion-technology dentifrice (0.454% SnF2; RDA ∼160-180; 'Test 2'). DH was assessed using tactile and evaporative (air) (measured by Schiff Sensitivity Scale and a visual rating scale [VRS]) stimuli. RESULTS: In total 249 subjects were randomized. All dentifrices yielded statistically significant improvements from baseline on all endpoints. The two DH-relief dentifrices ranked highest in terms of improvement in scores over the control dentifrices. While there was a clear differentiation between Test 1 and control dentifrices on both measures at 4/8 weeks, for Test 2, statistically significant improvements in Schiff scores were observed over all controls at Week 4 but only over three at Week 8. At Week 4 none of the controls separated from Test 2 on tactile threshold; all separated by Week 8. VRS scores did not separate test and control dentifrices. Dentifrices were generally well-tolerated. CONCLUSIONS: The six negative-control dentifrices can be used to assess dentifrices considered to be effective in reducing DH. Although response ranges for commercially available negative controls varied, these results may begin to set acceptable performance ranges for control dentifrices in DH trials.

A randomised clinical in situ study to evaluate the effects of novel low abrasivity anti-sensitivity dentifrices on dentine wear.

OBJECTIVES: To compare the abrasive wear on human dentine in an in situ model associated with use of an experimental low abrasivity anti-sensitivity dentifrice containing 1% alumina and 5% sodium tripolyphosphate (STP) with an experimental ultra-low abrasivity non-alumina 5% STP dentifrice, a higher abrasivity daily-use whitening dentifrice, and water as controls. METHODS: This was a single-centre, single-blind, randomised, split-mouth, four-treatment, two-period, crossover in situ study in 29 healthy subjects. Subjects wore bilateral lower buccal appliances, each fitted with four dentine specimens. Study treatments were applied ex vivo (three times daily). Dentine loss was measured by non-contact profilometry after 5, 10 and 15days' treatment. RESULTS: All 29 subjects were included in the efficacy analysis. Significantly less dentine loss was associated with brushing with the low and ultra-low abrasivity dentifrices than with the higher abrasivity dentifrice at all timepoints (p<0.01). Brushing with ultra-low abrasivity dentifrice or water resulted in statistically significantly less dentine loss compared with brushing with the low abrasivity dentifrice at all timepoints (p<0.05). Dentine loss after brushing with ultra-low abrasivity dentifrice was not significantly different from brushing with water. CONCLUSIONS: The degree of dentine loss observed in this in situ model reflected the abrasivity of the study dentifrices. Brushing with low or ultra-low abrasivity STP-containing anti-sensitivity dentifrices resulted in significantly less dentine loss (equating to dentine wear) than with a higher abrasivity daily-use whitening dentifrice.

Fluoride gel supplemented with sodium hexametaphosphate reduces enamel erosive wear in situ.

OBJECTIVE: This study evaluated the effect of fluoride gels, supplemented or not with sodium hexametaphosphate (HMP), on enamel erosive wear in situ. METHODS: Twelve healthy volunteers wore palatal appliances containing four bovine enamel discs. Subjects were randomly allocated into four experimental phases (double-blind, crossover protocol) according to the gels: Placebo (no fluoride or HMP), 1% NaF, 2% NaF, and 1% NaF+9% HMP. Enamel discs were selected after polishing and surface hardness analysis, and treated only once with the respective gels prior to each experimental phase. Erosion (ERO) was performed by extra-oral immersion of the appliance in 0.05M citric acid, pH 3.2 (four times/day, five minutes each, 5 days). Additional abrasion (ERO+ABR) was produced on only two discs by toothbrushing with fluoridated dentifrice after ERO (four times/day, 30s, 5 days). The specimens were submitted to profilometry and hardness analysis. The results were analyzed by two-way ANOVA and the Student-Newman-Keuls test (p<0.05). RESULTS: The 1% NaF+9% HMP gel promoted significantly lower enamel wear for ERO compared to the other groups, being statistically lower than 1% NaF and Placebo for ERO+ABR. Similarly, the lowest values of integrated lesion area were found for 1% NaF+9% HMP and 2% NaF, respectively, for ERO and ERO+ABR. CONCLUSION: The addition of HMP to the 1% NaF gel promoted greater protective effect against ERO and ERO+ABR compared to the 1% NaF gel, achieving similar protective levels to those seen for the 2% NaF gel. CLINICAL SIGNIFICANCE: Gel containing 1% NaF+9% HMP showed a high anti-erosive potential, being a safer alternative when compared to a conventional 2% NaF gel.

Effect of different concentrations of fluoride in dentifrices on dentin erosion subjected or not to abrasion in situ/ex vivo.

This in situ/ex vivo study assessed the effect of different concentrations of fluoride in dentifrices on dentin subjected to erosion or to erosion plus abrasion. Ten volunteers took part in this crossover and double-blind study performed in 3 phases (7 days). They wore acrylic palatal appliances containing 4 bovine dentin blocks divided in two rows: erosion and erosion plus abrasion. The blocks were subjected to erosion by immersion ex vivo in a cola drink (60 s, pH 2.6) 4 times daily. During this step, the volunteers brushed their teeth with one of three dentifrices D (5,000 ppm F, NaF, silica); C (1,100 ppm F, NaF, silica) and placebo (22 ppm F, silica). Then, the respective dentifrice slurry (1:3) was dripped on dentin surfaces. While no further treatment was performed in one row, the other row was brushed using an electric toothbrush for 30 s ex vivo. The appliances were replaced in the mouth and the volunteers rinsed with water. Dentin loss was determined by profilometry and analyzed by 2-way ANOVA/Bonferroni test (a = 0.05). Dentin loss after erosive-abrasive wear was significantly greater than after erosion alone. Wear was significantly higher for the placebo than for the D and C dentifrices, which were not significantly different from each other. It can be concluded that the presence of fluoride concentrations around 1,100 ppm in dentifrices is important to reduce dentin wear by erosion and erosion + abrasion, but the protective effect does not increase with fluoride concentration.

Influence of fluoride dentifrice on brushing abrasion of eroded human enamel: an in situ/ex vivo study.

This in situ/ex vivo study assessed the effect of fluoride dentifrice on eroded enamel subjected to brushing abrasion. In a crossover study performed in 2 phases, 10 volunteers wore acrylic palatal appliances, each containing 3 human enamel blocks. Dentifrice was used to brush the volunteers' teeth and the specimens subjected to abrasion. In phases A and B the dentifrices used had the same formulation, except for the absence or presence of fluoride, respectively. The blocks were subjected to erosion by immersion of the appliances in a cola drink for 5 min, 4 times a day. Then the blocks were brushed, and the appliance was replaced into the mouth. Enamel alterations were determined using profilometry and percentage change in surface microhardness (%SMHC) tests. The data were tested using the paired t test. The mean wear values (+/-SD, microm) were: group A 6.84 +/- 1.72 and group B 5.38 +/- 1.21 (p = 0.04). The mean %SMHC values (+/-SD) were: group A 54.6 +/- 16.2 and group B 45.7 +/- 6.8 (p = 0.04). Fluoride dentifrice had a protective effect on eroded enamel subjected to brushing abrasion.

The effect of a triclosan/copolymer/fluoride liquid dentifrice on interproximal enamel remineralization and fluoride uptake.

BACKGROUND: The authors measured the enamel remineralization of dental interproximal surfaces by a triclosan/copolymer/fluoride liquid dentifrice to test its performance against that of a standard toothpaste. METHODS: In a randomized, crossover, blinded, in situ protocol, the authors fitted 19 healthy adult subjects with mandibular appliances holding bilateral, interproximal bovine enamel slabs. They measured initial abrasion levels and fluoride content. In a two-phase crossover protocol, they evaluated the percentage of surface mineral recovery, or SMR, and fluoride uptake caused by the experimental dentifrice and a fluoride-containing traditional control toothpaste. RESULTS: Abrasion depths were similar and not different statistically (P > .05). The interproximal blocks exposed to the triclosan-containing liquid dentifrice had a mean fluoride uptake that was nearly 100 parts per million (13.1 percent) greater than that achieved with the American Dental Association-accepted control dentifrice. This finding, while not statistically significant, may indicate enhanced performance of the experimental dentifrice because the initial enamel slab abrasion depths were shown to be quite uniform. Moreover, the blocks exposed to the experimental toothpaste had a 49.8 percent SMR, while the positive control blocks had an SMR of only 36.9 percent. This enhanced remineralization performance was statistically significant (P < .05). CONCLUSIONS: This is the first study to show enhanced performance of a triclosan-containing liquid dentifrice in preventing interproximal dental caries. The difference in percentage of SMR was statistically significant and is likely to be clinically relevant. CLINICAL IMPLICATION: The results of this preliminary study offer evidence supporting clinicians' recommendation of the new liquid dentifrice to patients who are prone to developing interproximal carious lesions.

Estado da superfície externa do esmalte submetido aos procedimentos de microabrasäo: estudo ao microscópio eletrônico de varredura / Scanning electron microscopy study of enamel surface submitted to microabrasion

Este estudo avaliou a repercussäo dos tratamentos de microabrasäo sobre a superfície do esmalte de dentes humanos utilizando o ácido hidroclorídrico a 18 por cento sozinho, o ácido hidroclorídrico a 18 por cento mais pedra pomes e o composto PREMA, "in vitro", empregando o microscópio eletrônico de varredura. Para isso, foram utilizados 23 pré-molares erupcionados, de pacientes na faixa etária de 11 a 14 anos, recém extraídos, por razöes ortodônticas e armazenados em soluçäo de álcool a 70 por cento. Os resultados mostraram que houve aumento da rugosidade nas superfícies tratadas, quando comparadas com as do grupo controle. O grupo tratado com ácido hidroclorídrico a 18 por cento sozinho exibiu predominância do padräo de desmineralizaçäo TIPO I, onde o centro do prisma foi preferencialmente removido, ao contrário do grupo tratado com esse ácido associado com a pedra pomes, que mostrou predominância do padräo de desmineralizaçäo TIPO II, onde a periferia do prima foi preferencialmente removida. A principal característica observada no grupo tratado com o PREMA foi a presença de vários riscos e ranhuras, bem como restos provenientes do composto. O padräo de desmineralizaçäo näo mostrou semelhança com estrutura prismática, sendo classificado com TIPO III