An interproximal model to determine the erosion-protective effect of calcium silicate, sodium phosphate, fluoride formulations.

OBJECTIVES: Previous work has shown the effectiveness of a newly developed interproximal model to differentiate between the amount of remineralization caused by toothpastes used with or without a dual-phase gel treatment system containing calcium silicate, sodium phosphate salts and fluoride to repair acid-softened enamel. The aim of this study was to utilize the same interproximal model to identify how effective calcium silicate phosphate toothpastes are at reducing surface softening in the early stages of erosion. The model was also used to identify the effect of increasing the frequency of acid exposure on the reduction in surface hardness. METHODS: Human enamel specimens were prepared and mounted in an interproximal face-to-face arrangement and exposed to a cycling regime of whole human saliva, treatment, artificial saliva and 1% citric acid pH 3.75. Specimens were measured by surface microhardness at baseline and after three and seven days. The frequency of acid exposure was increased from 2 to 4 cycles a day for the second part of the study. RESULTS: The results showed that specimens treated with the calcium silicate phosphate toothpastes softened less than those treated with control fluoridated or non-fluoride toothpastes at each time point and following an increase in the frequency of acid exposure. SIGNIFICANCE: This work has demonstrated how an interproximal model can also be successfully used to determine differences in the erosion protection of various treatments as well as determining how they perform when the frequency of acid exposure is increased.

Tooth whitening evaluation of blue covarine containing toothpastes.

OBJECTIVES: To measure the tooth whitening effects delivered immediately after brushing with silica-based toothpastes containing blue covarine in vitro and in vivo. METHODS: Salivary pellicle coated human extracted teeth were brushed with either a slurry of a toothpaste containing blue covarine (BC), a formulation containing an increased level of blue covarine (BC+) or a negative control toothpaste containing no blue covarine. The colour of the specimens were measured in vitro using either a Minolta chromameter or a VITA Easyshade spectrophotometer, before and after brushing and changes in CIELAB values and tooth Whiteness Index (WIO) values calculated. In a double-blind cross-over clinical study, subjects brushed with either BC or BC+ toothpaste and tooth colour changes were measured with a digital image analysis system. RESULTS: The in vitro studies demonstrated that toothpastes containing blue covarine gave a significantly (p<0.05) greater change in b* and WIO values than the negative control toothpaste; the BC+ toothpaste gave a significantly greater increase in b* and WIO values than the BC toothpaste, and BC+ gave a significant increase in shade change versus the negative control. Clinical results showed that BC and BC+ gave a significant reduction in b* (p<0.0001) and increase in WIO (p<0.0001) from baseline indicating significant tooth whitening had occurred. The parameter changes were significantly greater when brushing with the BC+ toothpaste than with the BC toothpaste (WIO p=0.006; b* p=0.013). CONCLUSIONS: Toothpastes containing blue covarine gave a statistically significant reduction in tooth yellowness and improvement in tooth whiteness immediately after brushing in both in vitro and clinical studies. In addition, the higher concentration blue covarine toothpaste gave statistically significant greater tooth whitening benefits than the lower concentration blue covarine toothpaste. CLINICAL SIGNIFICANCE: The silica-based toothpastes containing blue covarine evaluated in the current study gave tooth whitening benefits immediately after one brush.

In vitro and clinical evaluation of optical tooth whitening toothpastes.

OBJECTIVES: To measure tooth whitening effects delivered immediately after brushing with silica-based toothpastes containing either blue covarine or a combination of blue covarine and FD&C Blue No. 1 in vitro and in vivo. METHODS: Salivary pellicle coated human extracted teeth were brushed with either a slurry of a toothpaste containing blue covarine (BC) or a formulation containing a matched level of blue covarine and FD&C Blue No.1 (BC+D). The colour of the specimens were measured in vitro using a colorimeter, before and after brushing and changes in CIELAB and tooth Whiteness Index (WIO) values calculated. In a double-blind cross-over clinical study, subjects brushed with BC toothpaste, a toothpaste containing increased levels of blue covarine (BC+) or BC+D toothpaste and tooth colour changes were measured with a digital image analysis system. RESULTS: The in vitro study demonstrated that BC+D gave a significantly (p=0.002) greater change in WIO value than BC. Clinical results showed that BC, BC+ and BC+D gave a significant increase in WIO (p<0.0001) from baseline. The WIO change was significantly greater when brushing with BC+D toothpaste than with either toothpaste BC (p<0.0001) or BC+ (p<0.05). CONCLUSIONS: Toothpastes containing blue covarine or a combination of blue covarine and FD&C Blue No. 1 gave a statistically significant improvement in tooth whiteness immediately after brushing in both in vitro and clinical studies. In addition, the toothpaste containing both blue covarine and FD&C Blue No. 1 gave statistically significant greater tooth whitening from baseline than the blue covarine containing toothpastes. CLINICAL SIGNIFICANCE: The silica-based toothpastes containing blue covarine or a combination of blue covarine and FD&C Blue No. 1 evaluated in the current study gave significant tooth whitening benefits immediately after one brush.

In vitro evaluation of a silica whitening toothpaste containing blue covarine on the colour of teeth containing anterior restoration materials.

OBJECTIVES: To investigate the effects of a silica-based whitening toothpaste containing blue covarine on the colour of restorations in extracted human teeth. METHODS: Human extracted teeth were mounted in acrylic resin. A cavity was cut into the enamel surface and the specimen restored with either glass ionomer or composite dental materials. Following 4 weeks storage in water, specimens were treated with either water, red wine or a toothpaste containing blue covarine (n=10) for 24h followed by brushing with a silica-based toothpaste. Specimens were imaged with a digital imaging system at baseline, after 24h treatment and after brushing with a silica-based toothpaste. CIELAB colour parameters were determined for the restoration and the whole specimen and overall mean colour changes calculated (ΔE). Baseline and post-brushing images were compared subjectively for overall stain and staining around the restoration margin. RESULTS: Red wine produced the largest ΔE values for whole specimens and for all restoration materials and the largest subjective stain scores for whole specimens and restoration margins. The red wine stain was not completely removed by brushing with a silica-based toothpaste. Comparisons of the red wine group with either the blue covarine toothpaste group or the water group were of statistical significance for all parameters (ANOVA, Tukey-Kramer, p<0.05). Following brushing with the silica-based toothpaste, specimens from the blue covarine toothpaste group were not significantly different (p>0.05) to the water group, for all restoration material types. CONCLUSIONS: Exaggerated treatment with a blue covarine containing toothpaste does not significantly affect the colour of the restoration or the restoration margin of the dental materials tested versus a water alone treatment. CLINICAL SIGNIFICANCE: The silica-based blue covarine containing toothpaste does not permanently stain the restorative materials tested or their margins.

Enhanced enamel benefits from a novel toothpaste and dual phase gel containing calcium silicate and sodium phosphate salts.

OBJECTIVE: To investigate the enamel health benefits of a novel toothpaste and a dual phase gel containing calcium silicate, sodium phosphate and fluoride. METHODS: Enamel demineralisation was assessed using two pH cycling protocols with either lactic acid or citric acid as the acid challenge. Remineralisation of lactic acid softened and citric acid softened enamel was assessed using a number of protocols. All demineralisation and remineralisation evaluation was by surface microhardness measurements. RESULTS: The novel calcium silicate/phosphate fluoride toothpaste inhibited enamel demineralisation to a significantly (p<0.05) greater extent than control formulations, including a fluoride control. The novel calcium silicate/phosphate fluoride toothpaste also showed significant (p<0.05) remineralisation of lactic acid and citric acid softened enamel compared to fluoride and non-fluoride controls. The addition of the novel calcium silicate/phosphate fluoride dual phase gel provided enhanced remineralisation of citric acid softened enamel compared to fluoride and non-fluoride controls. CONCLUSIONS: These studies show that formulations containing calcium silicate, sodium phosphate salts and fluoride provide enhanced enamel demineralisation and remineralisation in vitro benefits. CLINICAL SIGNIFICANCE: The novel oral care formulations containing calcium silicate, sodium phosphate salts and fluoride is a new approach to the protection of enamel from acid attacks and the repair of demineralised enamel, leading to increased dental hard tissue benefits.

The effect of toothpaste concentration on enamel and dentine wear in vitro.

OBJECTIVES: To determine the effect of toothpaste concentration on enamel and dentine wear in vitro and to model the effects of toothpaste abrasion upon dilution during toothbrushing in vivo. METHODS: Polished human enamel/dentine specimens were indented with a Knoop diamond and the enamel-dentine junction profiled. Specimens were brushed for 1200s with toothpastes with differing relative dentine abrasivity (RDA), either Toothpaste A (RDA=90) or Toothpaste B (RDA=200), using a toothbrush mounted in a brushing machine. The toothpastes were dispersed in water and 1% sodium carboxymethyl cellulose to give a range of toothpaste concentrations. After brushing the Knoop indent length and the enamel-dentine step were remeasured and the wear to the enamel and dentine calculated. An equation for modelling the decrease in toothpaste concentration with brushing time was found using published in vivo data and used to estimate the level of dentine wear during in vivo brushing. RESULTS: The mean enamel wear was in the range 0.03-0.11µm and there was only a small but non-significant (p>0.05) increase in enamel wear with toothpaste concentration. The mean dentine wear was in the range 0.28-27.63µm and the dentine wear increased significantly (p<0.05) with toothpaste concentration, with Toothpaste B giving more wear than Toothpaste A. Analysis with published in vivo data showed that 50% of dentine wear occurs in the first 20s of brushing and that the wear approaches a plateau value with brushing time as the toothpaste concentration is reduced. CONCLUSIONS: Enamel wear increases only slightly with toothpaste concentration whereas dentine wear increases with toothpaste concentration.

Evaluation of a 6% hydrogen peroxide tooth-whitening gel on enamel microhardness after extended use.

OBJECTIVES: To evaluate the effects of a 6% hydrogen peroxide tooth whitener, Xtra White, on sound human enamel microhardness in vitro after an extended and exaggerated simulated 8 weeks of product use. METHOD AND MATERIALS: Polished human enamel specimens were prepared and baseline microhardness and color measurements determined. The enamel specimens were exposed to a fluoride-containing toothpaste for 30 seconds and then exposed to water, Xtra White, a control carbopol gel containing no hydrogen peroxide, or a carbonated beverage (each group, n = 8) for 20 minutes. Specimens were exposed to whole saliva at all other times. In order to simulate 8 weeks of extended product use, quadruple the length of the manufacturer's instructions, 112 treatments, were conducted. Microhardness measurements were taken after 2, 4, 6, and 8 weeks of simulated treatments, and color was measured after 2 and 8 weeks. RESULTS: The Xtra White-treated specimens showed a statistically significant (P < .0001) increase in L* and decrease in b* compared to the water-treated specimens after 2 weeks simulated use, indicating bleaching had occurred. The carbonated beverage-treated specimens were significantly softened (P = .0009) compared to baseline after only 1 treatment. The carbopol gel-treated specimens were significantly softened (P = .0028) after 2 weeks of simulated treatments compared to baseline. There were no statistically significant differences in enamel microhardness between baseline and all treatment times for XW and water groups. CONCLUSION: Xtra White does not have any deleterious effects on sound human enamel microhardness after an extended and exaggerated simulated 8 weeks of product use.

A novel optical approach to achieving tooth whitening.

OBJECTIVE: To investigate a new optical approach to tooth whitening by enhancing the measurement and perception of tooth whiteness using blue coloured materials deposited onto the tooth surface. METHODS: Salivary pellicle coated human extracted teeth or polished enamel specimens were used as substrates and their colour was measured using a colorimeter in the CIELAB mode. Whole teeth were treated with a range of blue dyes and pigments and the colour measured following rinsing with water. Whole teeth were treated with Blue Covarine for 30 s, rinsed with water and colour changes assessed via colorimetric and visual assessment with a Vita Shade guide under controlled lighting (D65). Deposition of Blue Covarine onto cut enamel specimens was investigated using time-of-flight secondary ion mass spectrometry (TOF-SIMS). Tooth colour changes were also investigated following brushing for 1 min with toothpaste formulations containing Blue Covarine. RESULTS: Blue Covarine gave a significantly greater deltab* shift (p < 0.0001) compared to water. Blue Covarine gave a mean Vita Shade change of 1.18 compared to the water control (-0.03) (p <0.0001) and an increase in objectively measured whiteness index (WIO) (p <0.0001). Blue Covarine was chemically detected on enamel surfaces using TOF-SIMS. Toothpaste formulations containing Blue Covarine gave improvements in tooth whiteness. CONCLUSIONS: Blue Covarine has been identified as a new approach to tooth whitening. Its mode of action involves deposition and retention on tooth surfaces where it alters the optical properties of the tooth. This gives rise to an increase in the overall measurement and perception of tooth whiteness.

The in vitro and in vivo validation of a mobile non-contact camera-based digital imaging system for tooth colour measurement.

OBJECTIVE: To assess the reproducibility of a mobile non-contact camera-based digital imaging system (DIS) for measuring tooth colour under in vitro and in vivo conditions. METHODS: One in vitro and two in vivo studies were performed using a mobile non-contact camera-based digital imaging system. In vitro study: two operators used the DIS to image 10 dry tooth specimens in a randomised order on three occasions. In vivo study 1:25 subjects with two natural, normally aligned, upper central incisors had their teeth imaged using the DIS on four consecutive days by one operator to measure day-to-day variability. On one of the four test days, duplicate images were collected by three different operators to measure inter- and intra-operator variability. In vivo study 2:11 subjects with two natural, normally aligned, upper central incisors had their teeth imaged using the DIS twice daily over three days within the same week to assess day-to-day variability. Three operators collected images from subjects in a randomised order to measure inter- and intra-operator variability. RESULTS: Subject-to-subject variability was the largest source of variation within the data. Pairwise correlations and concordance coefficients were > 0.7 for each operator, demonstrating good precision and excellent operator agreement in each of the studies. Intraclass correlation coefficients (ICCs) for each operator indicate that day-to-day reliability was good to excellent, where all ICC's where > 0.75 for each operator. CONCLUSION: The mobile non-contact camera-based digital imaging system was shown to be a reproducible means of measuring tooth colour in both in vitro and in vivo experiments.

Evaluation of a new silica whitening toothpaste containing blue covarine on the colour of anterior restoration materials in vitro.

OBJECTIVES: The aims of this study were to evaluate the effects of a novel silica-based blue covarine whitening toothpaste on the colour of anterior restoration materials. METHODS: Restoration materials (three glass ionomers, three resin composites) were cast into disks (10 mm diameter, 2 mm thick) using cylindrical moulds. Specimens were immersed in pooled whole saliva prior to exposure to staining materials via one of two protocols. CIELAB colour measurements were taken at baseline and after each stage of the procedures. In one protocol, specimens were brushed with 10 ml of 33% (w/w) silica whitening toothpaste containing blue covarine slurry in water four times, for 10 min each time, with control specimens being immersed in water or red wine for the same period. Disks were re-immersed in saliva for 2 h between cycles. In the other protocol, specimens were immersed in 20 ml of water, red wine or silica whitening toothpaste containing blue covarine slurry for 96 h with colour measurements being taken afterwards. The second protocol disks were then brushed for 2 min using a non-whitening silica paste and further colour measurements made. Colour differences were then calculated. RESULTS: At the end of both protocols the disks treated with silica whitening toothpaste containing blue covarine were not significantly different from the water controls (p > 0.1) in contrast to those treated with red wine. Even prior to brushing in the second protocol, there was no significant staining from the new toothpaste compared to the water control (p > 0.1). CONCLUSIONS: There was no significant staining by the silica whitening toothpaste containing blue covarine on any of these materials.

In vitro cleaning, abrasion and fluoride efficacy of a new silica based whitening toothpaste containing blue covarine.

OBJECTIVES: To investigate the stain removal ability, abrasivity towards enamel and dentine, and fluoride efficacy of a new silica based blue covarine whitening toothpaste in vitro. METHODS: Stain removal was assessed by brushing artificially stained bovine specimens with slurries of either the new toothpaste or one of two whitening products or a non-whitening silica product. Toothpaste abrasivity was assessed by brushing enamel/dentine specimens with slurries of either the new toothpaste, a whitening toothpaste or a non-whitening toothpaste and measuring the wear via a combination of changes in geometry of Knoop indents and surface profilometry. Fluoride efficacy was assessed using remineralisation, demineralisation and fluoride-uptake methods. RESULTS: The in vitro cleaning study showed that the silica based blue covarine whitening toothpaste removed significantly (p < 0.05) more stain than the non-whitening toothpaste and was as effective as the two marketed silica based whitening toothpastes. This enhanced tooth whitening benefit did not give rise to a concomitant statistically significant increase in the level of wear to enamel and dentine compared to the non-whitening silica based toothpaste. The fluoride efficacy was superior to a non-fluoridated control and was as effective as a clinically tested formulation containing the same fluoride source. CONCLUSIONS: The studies show that the new whitening toothpaste is effective in extrinsic stain removal, does not have an undue degree of abrasivity to enamel or dentine compared to other relevant commercially available products, and is an efficacious source of fluoride.

The protective nature of pellicle towards toothpaste abrasion on enamel and dentine.

OBJECTIVES: To determine the protective nature of pellicle towards toothpaste abrasion. METHODS: The enamel region of human enamel-dentine blocks was indented with a Knoop diamond and the profile across the enamel-dentine junction was measured. Blocks were either exposed to deionised water or placed onto intra-oral appliances and worn in the mouth to produce in situ pellicles. This was followed by a 10-day period of tooth brushing experiments. Each day, specimens were brushed with a slurry of either Toothpaste A (RDA=90) or Toothpaste B (RDA=204) for 25 cycles (10s) on a brushing machine. This was repeated three times per day for a total of 750 brushing cycles. Between brushing cycles specimens were returned to water or in situ. The geometry of the Knoop indents and the enamel-dentine profile were re-measured and the enamel and dentine wear calculated. Specimens were also prepared for TEM analyses. RESULTS: The mean enamel wear (microm) for Toothpastes A and B (water) was 0.23 and 0.06, and for Toothpastes A and B (in situ) was 0.03 and 0.08, respectively. The mean dentine wear (microm) for Toothpastes A and B (water) was 5.08 and 6.03, and for Toothpastes A and B (in situ) was 1.94 and 1.70, respectively. For Toothpaste A, the presence of in situ pellicle significantly (p<0.05) reduced enamel and dentine wear compared to water and for Toothpaste B, dentine wear was significantly reduced compared to water. After tooth brushing, residues of the in situ pellicle layer could be detected on enamel and dentine surfaces by TEM analysis. CONCLUSIONS: The study has demonstrated for the first time that the presence of pellicle can significantly reduce toothpaste abrasion.