Toothpaste Slurry Research Articles

Rinsing with Fluoride Toothpaste Slurry may Prevent Dental Caries in Orthodontic Patients

Modified fluoride toothpaste technique reduces caries in orthodontic patients: a longitudinal, randomized clinical trial. Al Mulla AH, Kharsa SA, Birkhed D. Am J Orthod Dentofacial Orthop 2010;138(3):285-91. Joana Cunha-Cruz, PhD What is the caries incidence of orthodontic patients using a modified oral hygiene technique compared with orthodontic patients using routine oral hygiene technique? Information not available Randomized controlled trial Level 2 Not applicable

Retention of o-cymen-5-ol and zinc on reconstructed human gingival tissue from a toothpaste formulation

To assess the retention of o-cymen-5-ol and zinc on reconstructed human gingival tissue delivered by topical applications of toothpaste formulated with 0.1%w/w o-cymen-5-ol and 0.6%w/w zinc chloride (ZnCl2). EpiGingival tissues were treated topically for 2 minutes with either solutions or toothpaste slurries containing o-cymen-5-ol and ZnCl2. Tissues were rinsed with water between application and the effects of repeat dosing for up to 6 occasions were investigated. Tissues were blot dried, extracted and o-cymen-5-ol and zinc were measured by HPLC and atomic absorption spectroscopy, respectively. Retention of o-cymen-5-ol and zinc delivered from solutions to EpiGingival tissues showed a dose response to the concentration and to the number of applications. Significantly higher concentrations of zinc were delivered to EpiGingival tissues by toothpaste compared to equivalent doses delivered from solution. Equivalent doses of o-cymen-5-ol were delivered from toothpaste and solution. No cytotoxic effects on the EpiGingival tissues, measured by MTT viability, were detected following application of test toothpaste compared to a water control. Reconstructed human gingival tissue proved to be an effective model for the assessment of active retention from topically applied formulations. The test toothpaste was effective in delivering o-cymen-5-ol and zinc to oral soft tissue in vitro.

Protection against enamel demineralisation using toothpastes containing o-cymen-5-ol, zinc chloride and sodium fluoride

To evaluate the ability of two experimental toothpastes containing 0.1%w/w o-cymen-5-ol, 0.6%w/w ZnCl2 and 0.320%w/w NaF to reduce demineralisation of sound human enamel compared with control toothpastes. Study 1: Specimens were treated with toothpaste slurries, followed by alternating periods in demineralising and neutral solutions. Demineralisation was assessed using surface microhardness (SMH). Study 2: Specimens were subjected to a 14 day cycling regime of alternating demineralisation/remineralisation with two toothpaste treatments per day, before and after demineralisation. Demineralisation was assessed by cross-sectional microhardness and mineral loss (ΔZ) was calculated. Test toothpastes were a) 0%w/w or 0.002%w/w NaF placebo, b) 0.055%w/w or 0.149%w/w NaF (dose response), c) 0.320%w/w NaF marketed product, d & e) 0.1%w/w o-cymen-5-ol, 0.6%w/w ZnCl2 and 0.320%w/w NaF (experimental toothpastes). Study 1: Mean±SE % of baseline hardness values were a) 48.0±2.1a, b) 66.7±1.7b, c) 82.9±1.9c, d) 91.7±1.4d and e) 94.6±2.1d. Study 2: Mean±SE ΔZ values were a) 2114±187a, b) 1206±132b, c) 303±89c, d) 19±73c, and e) -10±55c. Letters represent different statistical groupings (P<0.05). In study 1, both experimental toothpastes were statistically superior to the marketed product and in study 2; they were at least as effective as the marketed product at reducing caries lesion development.

In vitro effects of novel toothpaste actives on components of oral malodour

To evaluate the efficacy of a novel toothpaste containing zinc ions and o-cymen-5-ol to reduce volatile sulfur compounds (VSCs) in in vitro models and to elucidate the mode of action for any activity observed. Three models were employed, a chemical neutralisation model to evaluate the chemical reactivity of toothpaste slurries to VSCs, a biofilm perfusion model to measure activity in an orally-relevant biofilm and a planktonic bacterial model to measure antimicrobial effects. The models showed that zinc ions were able to react chemically with hydrogen sulfide to remove this odorous component of halitotic breath. This activity was confirmed within a complex biofilm model, with over 90% of hydrogen sulfide removed from perfusate gas by a slurry of the test toothpaste. This work provides a mode of action for the clinically observed reduction in VSCs seen for up to 12 hours post brushing with this novel toothpaste.

In vitro evaluation of fluoride and calcium sodium phosphosilicate toothpastes, on root dentine caries lesions

Objectives The aim of this in vitro study was to assess the effect of toothpastes containing three different sodium fluoride concentrations and a calcium sodium phosphosilicate system, on root dentine demineralization and remineralization. Methods During a fourteen-day pH-cycling protocol, pre-softened bovine root dentine specimens were immersed twice daily, before and after the demineralization periods, for 2 min, in the following toothpaste slurries: (a) non-fluoridated (control), (b) 7.5% calcium sodium phosphosilicate, (c) 1450 ppm F, (d) 2800 ppm F, and (e) 5000 ppm F. Subsequently, the slabs were subjected to a fifty-hour acid resistance test. Knoop microhardness at different lesion depths was assessed in specimen cross-sections and KHN values were converted to vol.% mineral. Comparisons between the groups were performed at each lesion depth through ANOVA-based tests and furthermore, regression analysis of the derived statistic of “integrated vol.% mineral loss” was carried out. Also, lesions were evaluated qualitatively using transmission and polarized light microscopy. Results The 5000 ppm F toothpaste group, during pH-cycling, presented significantly less total vol.% mineral loss and subsequently exhibited considerably increased surface acid resistance, compared to all the other tested groups. The calcium sodium phosphosilicate toothpaste, during pH-cycling, inhibited demineralization and/or promoted remineralization of the surface layers significantly more effectively than the control group nevertheless, subsequently, the acid resistance of the calcium sodium phosphosilicate dentifrice group was similar to that of the control group. These observations were confirmed by microscopic examination of the lesions. Conclusions Under the present experimental conditions, the 5000 ppm F toothpaste, promoted remineralization and inhibited demineralization more effectively, than the other tested toothpastes.

Influence of fluoride–detergent combinations on the visco‐elasticity of adsorbed salivary protein films

The visco-elasticity of salivary-protein films is related to mouthfeel, lubrication, biofilm formation, and protection against erosion and is influenced by the adsorption of toothpaste components. The thickness and the visco-elasticity of hydrated films (determined using a quartz crystal microbalance) of 2-h-old in vitro-adsorbed salivary-protein films were 43.5 nm and 9.4 MHz, respectively, whereas the dehydrated thickness, measured using X-ray photoelectron spectroscopy, was 2.4 nm. Treatment with toothpaste slurries decreased the thickness of the film, depending on the fluoride-detergent combination involved. Secondary exposure to saliva resulted in a regained thickness of the film to a level similar to its original thickness; however, no association was found between the thickness of hydrated and dehydrated films, indicating differences in film structure. Treatment with stannous fluoride/sodium lauryl sulphate (SnF(2)/SLS)-containing toothpaste slurries yielded a strong, immediate two-fold increase in characteristic film frequency (f(c)) with respect to untreated films, indicating cross-linking in adsorbed salivary-protein films by Sn(2+) that was absent when SLS was replaced with sodium hexametaphosphate (NaHMP). Secondary exposure to saliva of films treated with SnF(2) caused a strong, six-fold increase in f(c) compared with primary salivary-protein films, regardless of whether SLS or NaHMP was the detergent. This suggests that ionized stannous is not directly available for cross-linking in combination with highly negatively charged NaHMP, but becomes slowly available after initial treatment to cause cross-linking during secondary exposure to saliva.

Clinical and antibacterial effect of an anti-inflammatory toothpaste formulation with Scutellaria baicalensis extract on experimental gingivitis

It was the aim of the study to evaluate the clinical and antibacterial effect of a dentifrice containing an anti-inflammatory plant extract (SB) versus a placebo (PLA) using an experimental gingivitis model. Forty subjects (20 per group) discontinued all oral hygiene measures for four teeth for a period of 21days using a shield (to generate a possible gingivitis) while they could brush the other teeth normally. After brushing, the shield was removed and teeth were treated with the randomly assigned toothpaste slurry for 1min. Löe and Silness gingival index (GI), Silness and Löe plaque index (PI), and biofilm vitality (VF%) were assessed at days0, 14, and 21, respectively. Subjects of the PLA group developed a GI of 0.82 ± 0.342 (day14) and 1.585 ± 0.218 (day21), while the data of the SB group were significantly reduced (0.355 ± 0.243 and 0.934 ± 0.342, p < 0.001). While PI was significantly reduced at all follow-up appointments, reductions in VF reached the level of significance only at day21. The results suggest that the new toothpaste formulation was able to significantly reduce the extent of gingivitis, plaque development, and vital flora.

The Role of Fluoride and Casein Phosphopeptide/Amorphous Calcium Phosphate in the Prevention of Erosive/Abrasive Wear in an in vitro Model Using Hydrochloric Acid

Objective: To investigate the effect of various fluoride compounds and casein phosphopeptide/amorphous calcium phosphate (CPP-ACP) on the reduction of erosive/abrasive tooth wear. Methods: Forty enamel samples were prepared from bovine lower incisors, stratified and allocated to 4 groups (1–4). Samples in group 1 remained untreated and served as negative controls. The test samples were treated for 2 min/day as follows: group 2 amine/sodium fluoride gel (pH 4.8; 12,500 ppm), group 3 sodium fluoride gel (pH 7.1; 12,500 ppm) and group 4 CPP-ACP-containing mousse. De- and remineralization cycling was performed for 20 days with 6 erosive attacks for 20 s with HCl (pH 3.0) per day. Samples were stored in artificial saliva between cycles and overnight. Toothbrushing (15 s; 60 strokes/min; load 2.5 N) with a toothpaste slurry was performed each day before the first and 1 h after the last erosive exposure. Tooth wear was measured by comparing baseline surface profiles with the corresponding posttreatment profiles. Results: Tooth wear was significantly reduced in groups 2 and 3 compared with group 1, while the enamel loss of group 4 was not significantly lower compared to the negative control group 1. Between the fluoride groups 2 and 3, no significant difference in tooth wear was recorded. Conclusion: Erosive/abrasive tooth wear under the conditions used could be reduced significantly by the daily application of fluoride gels, irrespective of the fluoride compound, while the application of CPP-ACP-containing mousse was less effective.

Effect of fluoride and of calcium sodium phosphosilicate toothpastes on pre-softened dentin demineralization and remineralization in vitro

Objectives The purpose of this in vitro study was to evaluate the effect of toothpastes containing sodium fluoride in different concentrations or a calcium sodium phosphosilicate system on pre-softened dentin demineralization and remineralization. Methods During a ten day pH-cycling protocol, pre-softened bovine root dentin slabs were immersed twice daily, after the demineralization periods, for 2 min, in the following toothpaste slurries: (a) non-fluoridated (control), (b) 7.5% calcium sodium phosphosilicate, (c) 1450 ppm F, (d) 2800 ppm F and (e) 5000 ppm F. Subsequently, the specimens were subjected to a 15-h acid resistance test. Surface microhardness was assessed initially and during the pH-cycling and the acid resistance test period. Repeated measurements in each group were analyzed through appropriate regression models for longitudinal data. Results All fluoride groups, during pH cycling, showed significantly less microhardness loss ( p ≤ 0.010, p ≤ 0.002, p ≤ 0.002) and subsequently exhibited increased acid resistance ( p ≤ 0.010, p ≤ 0.001, p ≤ 0.001) compared to the control. The 5000 ppm and 2800 ppm F toothpastes, inhibited demineralization significantly more effectively than the 1450 ppm F ( p ≤ 0.001, p ≤ 0.030) and the calcium sodium phosphosilicate toothpaste ( p ≤ 0.001), while no significant differences were found between the two high fluoride groups ( p = 0.130). The calcium sodium phosphosilicate toothpaste, during pH cycling showed a difference that approached statistical significance compared to control ( p = 0.079), but its acid resistance behavior was similar to control ( p = 0.610). Conclusions Under these experimental conditions, the high fluoride toothpastes promoted remineralization and inhibited demineralization more effectively, than the 1450 ppm F, the non-fluoridated (control) and the calcium sodium phosphosilicate toothpastes.

Preventive Effect of Commercial Desensitizing Toothpastes on Bovine Enamel Erosion in vitro

This study evaluated in vitro commercial desensitizing toothpastes with respect to the prevention of erosion and explored the effect of their agents alone or in combination with fluoride. Bovine enamel blocks were randomly allocated to five groups of 20 and exposed to: Sensodyne ProNamel (1,425 ppm F as NaF, 5% KNO₃), Sensodyne Original (no fluoride, 10% SrCl₂), Colgate Sensitive (1,450 ppm F as sodium monofluorophosphate, 5% K citrate), Crest (fluoride-only toothpaste, 1,100 ppm F as NaF) and water (negative control). A second experiment was conducted with experimental dentifrices containing fluoride (NaF, 1,100 ppm F), 10% SrCl₂, 5% KNO₃or 5% K citrate alone or the latter three combined with F. The samples were submitted to four cycles, alternating demineralization (cola, 10 min) and remineralization (artificial saliva, 1 h). Before and between cyclic de- and remineralization, blocks were treated with slurries of the respective toothpastes or water (1 min). Erosive tissue loss was analyzed by profilometry. Data were analyzed by Kruskal-Wallis and Dunn’s tests (p < 0.05). The mean erosion depth (± SE, µm) was significantly less for Colgate Sensitive (0.04 ± 0.00), Sensodyne Original (0.06 ± 0.01) and Crest (0.07 ± 0.01) than for Sensodyne ProNamel (2.36 ± 0.25) or water (2.92 ± 0.24), which did not significantly differ from each other. Both F and the desensitizing agents alone reduced erosion, but no additive effect was found. In addition, the combination of F and KNO₃ did not reduce erosion. These in vitro results suggest that the presence of fluoride or desensitizing substances in toothpastes, alone or in combination, can reduce erosion of enamel, but this is not valid for all the formulations.

Surface deterioration of dental materials after simulated toothbrushing in relation to brushing time and load

Objectives (1) To evaluate the changes in surface roughness and gloss after simulated toothbrushing of 9 composite materials and 2 ceramic materials in relation to brushing time and load in vitro; (2) to assess the relationship between surface gloss and surface roughness. Methods Eight flat specimens of composite materials (microfilled: Adoro, Filtek Supreme, Heliomolar; microhybrid: Four Seasons, Tetric EvoCeram; hybrid: Compoglass F, Targis, Tetric Ceram; macrohybrid: Grandio), two ceramic materials (IPS d.SIGN and IPS Empress polished) were fabricated according to the manufacturer's instructions and optimally polished with up to 4000 grit SiC. The specimens were subjected to a toothbrushing (TB) simulation device (Willytec) with rotating movements, toothpaste slurry and at three different loads (100 g/250 g/350 g). At hourly intervals from 1 h to 10 h TB, mean surface roughness Ra was measured with an optical sensor and the surface gloss (Gl) with a glossmeter. Statistical analysis was performed for log-transformed Ra data applying two-way ANOVA to evaluate the interaction between load and material and load and brushing time. Results There was a significant interaction between material and load as well as between load and brushing time ( p < 0.0001). The microhybrid and hybrid materials demonstrated more surface deterioration with higher loads, whereas with the microfilled resins Heliomolar and Adoro it was vice versa. For ceramic materials, no or little deterioration was observed over time and independent of the load. The ceramic materials and 3 of the composite materials (roughness) showed no further deterioration after 5 h of toothbrushing. Mean surface gloss was the parameter which discriminated best between the materials, followed by mean surface roughness Ra. There was a strong correlation between surface gloss and surface roughness for all the materials except the ceramics. The evaluation of the deterioration curves of individual specimens revealed a more or less synchronous course suspecting hinting specific external conditions and not showing the true variability in relation to the tested material. Significance The surface roughness and gloss of dental materials changes with brushing time and load and thus results in different material rankings. Apart from Grandio, the hybrid composite resins were more prone to surface changes than microfilled composites. The deterioration potential of a composite material can be quickly assessed by measuring surface gloss. For this purpose, a brushing time of 10 h (=72,000 strokes) is needed. In further comparative studies, specimens of different materials should be tested in one series to estimate the true variability.

Effect on de novo plaque formation of rinsing with toothpaste slurries and water solutions with a high fluoride concentration (5,000 ppm)

The aim of this study was to evaluate the effect, on de novo plaque formation, of rinsing with toothpaste slurries and water solutions containing a high concentration of fluoride (F). Sixteen subjects rinsed three times per day for 4 d with dentifrice slurries containing 5,000, 1,500, and 500 ppm F, while 12 subjects rinsed with water solutions containing 5,000, 1,500, 500, and 0 ppm F, and 1.5% sodium lauryl sulphate (SLS). Plaque was scored [using the Quigley & Hein index (QHI)] after each 4-d period. Plaque samples for F analysis were collected. Significantly less plaque was scored for the dentifrice slurry containing 5,000 ppm F (buccal and all surfaces) and for 1.5% SLS (buccal surfaces). The differences in plaque scores between dentifrice containing 5,000 and 1,500 ppm F were 19% for all surfaces and 33% for buccal surfaces. The difference between the water solutions containing 1.5% SLS and 1,500 ppm F for buccal surfaces was 23%; the corresponding difference for 5,000 ppm F was 17%. The dentifrice slurry containing 5,000 ppm F accumulated 56% more F in plaque. The combination of high levels of F and SLS in dentifrice reduces de novo plaque formation and increases the accumulation of F in plaque after 4 d.

Thickness of softened human enamel removed by toothbrush abrasion: an in vitro study

The aim of the study was to assess the thickness of softened enamel removed by toothbrushing. Human enamel specimens were indented with a Knoop diamond. Softening was performed with citric acid or orange juice. The specimens were brushed in a brushing machine with a manual soft toothbrush in toothpaste slurry or in artificial saliva. Enamel loss was calculated from the change in indentation depth of the same indent before and after abrasion. Mean surface losses (95% confidence interval) were recorded in treatment groups (in nanometers): (1) citric acid, abrasion with slurry = 339 (280-398); (2) citric acid, abrasion with artificial saliva = 16 (5-27); (3) orange juice, abrasion with slurry = 268 (233-303); (4) orange juice, abrasion with artificial saliva = 14 (5-23); (5) no softening, abrasion with slurry = 28 (10-46). The calculated thickness of the softened enamel varied between 254 and 323 nm, depending on the acid used.

Abrasion of eroded dentin caused by toothpaste slurries of different abrasivity and toothbrushes of different filament diameter

Objective This study aimed to evaluate the impact of toothpaste slurry abrasivity and toothbrush filament diameter on abrasion of eroded dentin in vitro. Methods Eroded dentin samples (hydrochloric acid, pH 2.6, 15 s) were brushed with 40 strokes in an automatic brushing machine using manual toothbrushes with different filament diameter (0.15, 0.20 or 0.25 mm). The toothbrushes were applied with a control slurry free of abrasive particles (RDA-value 10) or toothpastes slurries with different abrasivity (RDA-values 20, 50 or 100). Each erosive–abrasive cycle was followed by storage of the dentin samples in artificial saliva for 3 h. After each 4 cycles, the samples were stored in artificial saliva for 15 h. After 60 cycles, dentin loss was measured by profilometry and statistically analysed by ANOVA and linear regression analysis. Results Dentin loss increased along with the RDA-value of the toothpaste slurries. The impact of the filament diameter on dentin loss was less evident compared to the RDA-value. However, toothbrushes with smaller filament stiffness caused higher dentin wear in all toothpaste slurry groups (RDA 20, 50 and 100) except for the paste-free control group (RDA 10). Conclusion Abrasion of eroded dentin increased along with the RDA-value of the toothpaste slurry and with decreasing filament diameter of the toothbrush.

The effect of casein phosphopeptide–amorphous calcium phosphate on erosive enamel and dentine wear by toothbrush abrasion

Objective In addition to its role as a remineralizing agent in preventing dental caries, calcium product (CPP–ACP) delivered as a mousse (Tooth Mousse ®, TM) can reduce erosion of enamel and dentine. The aim of this study was to determine whether CPP–ACP could also reduce erosive tooth wear involving toothbrush abrasion. Methods Flat, polished enamel and dentine specimens ( n = 72) were subjected to 10 wear regimes, with each regime involving erosion in 0.3% citric acid (pH 3.2) for 10 min followed by toothbrush abrasion in a slurry of fluoride-free toothpaste and artificial saliva (1:3 ratio by weight) under a load of 2N for 200 cycles. The specimens were immersed in artificial saliva for 2 h between wear regimes. In the experimental group 1, TM (containing CPP–ACP) was applied at the beginning of each wear episode for 5 min whereas TM− (without CPP–ACP) was applied in the experimental group 2. No mousse was applied in the control group. Results TM significantly reduced enamel wear (mean ± S.E., 1.26 ± 0.33 μm in the experimental group 1 vs 3.48 ± 0.43 μm in the control group) and dentine wear (2.16 ± 0.89 μm in the experimental group 1 vs 10.29 ± 1.64 μm in the control group), and dentine wear was significantly less in the experimental group 1 than in the experimental group 2 (5.75 ± 0.98 μm). Conclusion The finding that TM reduced erosive tooth wear involving toothbrush abrasion, probably by remineralizing and lubricating eroded tooth surfaces, may have implications in the management of tooth wear.

Effect of a 5000 ppm fluoride toothpaste and a 250 ppm fluoride mouth rinse on the demineralisation of dentin surfaces

BackgroundThe purpose of this study was to test the null hypothesis that there is no difference between the effect of (1) a 5000 ppm fluoride toothpaste, and (2) a 250 ppm fluoride mouth rinse on demineralized human dentin surfaces, against the alternative hypothesis of a difference.FindingsDentin specimens were obtained from the cervical regions of 45 extracted human third molars. Half the surface of each specimen was sealed with a self-etching adhesive system and served as the reference surface. The dentin specimens were randomly assigned to one of the three groups, 5000 ppm fluoride toothpaste (Duraphat), 250 ppm fluoride mouth rinse (Meridol) and distilled water (negative control).An intraoral appliance was made for one volunteer. In each test cycle, 15 specimens were inserted in the appliance and worn for 24 hours a day, over a period of three weeks.Once daily, the appliance was immersed in the agent being tested; either toothpaste slurry, mouth rinse or distilled water for 60 seconds.Demineralization was assessed in terms of lesion depth (μm) and mineral loss (vol. % × μm) by transversal microradiography. Data analysis was accomplished using Kolmogorov-Smirnov test and ANOVA (SPSS 12.0).Statistically significant differences for mineral loss and lesion depth were found between the toothpaste and the mouth rinse as well as between the toothpaste and the control group, but not between the mouth rinse and the control group.ConclusionWithin the limitations of this study, the results suggest that treatment of demineralised dentin with a toothpaste containing 5000 ppm fluoride may considerably reduce mineral loss and lesion depth on exposed dentin.

Controlled Toothbrush Abrasion of Softened Human Enamel

The aim of this in vitro study was to compare toothbrush abrasion of softened enamel after brushing with two (soft and hard) toothbrushes. One hundred and fifty-six human enamel specimens were indented with a Knoop diamond. Salivary pellicle was formed in vitro over a period of 3 h. Erosive lesions were produced by means of 1% citric acid. A force-measuring device allowed a controlled toothbrushing force of 1.5 N. The specimens were brushed either in toothpaste slurry or with toothpaste in artificial saliva for 15 s. Enamel loss was calculated from the change in indentation depth of the same indent before and after abrasion. Mean surface losses (95% CI) were recorded in ten treatment groups: (1) soft toothbrush only [28 (17–39) nm]; (2) hard toothbrush only [25 (16–34) nm]; (3) soft toothbrush in Sensodyne MultiCare slurry [46 (27–65) nm]; (4) hard toothbrush in Sensodyne MultiCare slurry [45 (24–66) nm]; (5) soft toothbrush in Colgate sensation white slurry [71 (55–87) nm]; (6) hard toothbrush in Colgate sensation white slurry [85 (60–110) nm]; (7) soft toothbrush with Sensodyne MultiCare [48 (39–57) nm]; (8) hard toothbrush with Sensodyne MultiCare [40 (29–51) nm]; (9) soft toothbrush with Colgate sensation white [51 (37–65) nm]; (10) hard toothbrush with Colgate sensation white [52 (36–68) nm]. Neither soft nor hard toothbrushes produced significantly different toothbrush abrasion of softened human enamel in this model (p > 0.05).

Is bovine dentine an appropriate substitute for human dentine in erosion/abrasion tests?

The study aimed to compare the dentine wear of primary and permanent human and bovine teeth because of erosion/abrasion and evaluate if bovine dentine is an appropriate substitute for human dentine in further erosion/abrasions tests. Dentine samples from deciduous molars and human third molars as well as from calves' and cattle's lower incisors were prepared and baseline surface profiles were recorded. Each day all samples were demineralized in 1% citric acid, tooth brushed with 100 brushing strokes with toothpaste slurry and stored in artificial saliva for the rest of the day. This cycle was run for 20 days. Afterwards, new surface profiles were recorded and dentine wear was calculated by a customized computer program. Dentine wear because of erosion/abrasion was not statistically, significantly different for human third molars and cattle's lower incisors (P = 0.7002). The dentine wear because of erosion/abrasion of deciduous molars and calves' lower incisors was significantly different (P < 0.0000). No statistically significant difference in the dentine wear of human third molars and cattle's lower incisors was observed, so that the use of cattle's lower incisors as substitute for adult human teeth for further investigations in erosion/abrasion studies could be accepted.

Removal of oral debris and bacteria during supervised tooth brushing

Objective To investigate foam generation during brushing, and the oral debris and bacteria removal efficacy of an experimental gel-to-foam dentifrice compared to a commercially-available dentifrice after brushing. Methods Thirty-four subjects participated in this blinded, crossover study. After a wash-out period prior to each session of product use, subjects reported to the site having abstained from oral hygiene, eating and drinking from 22:00 h on the evening prior to treatment visits. The subjects brushed with a weighed dose of assigned paste and were asked to expectorate their toothpaste slurry into a collection vessel at 30 and 60 seconds during supervised brushing. The expectorated foam was measured immediately, after which subjects rinsed with 10 ml of sterile water and expectorated into the same vessel. Samples were placed on ice and immediately transported to the laboratory for analysis. Bacteria (total anaerobes and VSC-producing bacteria) were enumerated using appropriate selective media. To calculate the amount of debris, a measured portion of the sample was deposited onto a pre-weighed dish and weighed. Dishes were dried thoroughly and weighed again after cooling. Results Use of the gel-to-foam dentifrice resulted in 105% greater foam volume compared with use of the control dentifrice (p<0.0001). Further, the gel-to-foam dentifrice removed 15.77% more debris than the control dentifrice (p-value = 0.0342). There was greater removal of total anaerobes and VSC-producing bacteria by the gel-to-foam dentifrice versus the control dentifrice (p-value < 0.0001). Conclusion Single use of a gel-to-foam dentifrice generated a greater volume of foam and removed a greater amount of oral debris and bacteria during brushing than a standard dentifrice.

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 (10 s) 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 (μm) 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 (μm) 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.