Wear of dentine in vitro by toothpaste abrasives and detergents alone and combined

Is the whitening effect of charcoal-based dentifrices related to their abrasive potential or the ability of charcoal to adsorb dyes?

OBJECTIVES

To evaluate if tooth color alteration of activated charcoal-based dentifrices may be attributed to the dye adsorption potential of charcoal (chemical action - C - slurry only) or to the association of dye adsorption with abrasion (chemo-mechanical action - CM- slurry/toothbrushing). Potential adverse effects in surface roughness, gloss, and wear were also assessed.

METHODS

Bovine enamel/dentin specimens were randomly allocated into the groups according to treatments and test model (n = 15): deionized water (negative control- NC); Colgate Maximum Anticaries Protection (conventional toothpaste- positive control- PC); Colgate Luminous White Activated Charcoal (LW); Oral-B 3D White Therapy Charcoal (WT); Curaprox Black is White (BW); Dermavita Whitemax (Activated charcoal powder- WP). Specimens were exposed to the C or CM models, in 28-day staining-treatment cycling. Color change (ΔE00), whiteness index (ΔWID), percentage of alteration of surface roughness (%Raalt), and gloss (%GUalt) were calculated. Additional specimens (n = 9) were indented with a Knoop diamond and subjected to 100,000 abrasion cycles. Enamel wear was determined by calculating the decrease in indentations geometry. Data were analyzed by ANOVA/Tukey tests (α = 0.05).

RESULTS

The CM-model produced lower color change (staining) than C (p = 0.0001). PC, LW, WT, BW, and WP showed similar color results for both models, differing from NC (p < 0.05).%Ra and%GU did not differ among the C-model groups (p > 0.05) and WP exhibited the highest variation (%Ra and%GU) under CM-model. Enamel wear values were lowest in the NC and PC groups, intermediate for LW, WT, BW, and highest for the WP (p < 0.05).

CONCLUSION

Activated charcoal-based dentifrices have a similar ability to minimize tooth staining as the conventional toothpaste, with increased enamel wear potential in the long term (after 100,000 cycles). The activated charcoal powder damaged the enamel surface, showing a higher deleterious effect on enamel roughness, gloss, and wear.

CLINICAL SIGNIFICANCE

Dentifrices containing activated charcoal do not provide superior results to minimize tooth staining compared to conventional toothpaste. Charcoal powder should be used with caution because it promotes higher superficial alterations on the enamel surface.

Effects of a commercial whitening toothpaste containing hydrogen peroxide and citric acid on dentin abrasion and erosion

BACKGROUND

Hydrogen peroxide (HP) and citric acid (CA), key contributors to toothpaste acidity, can lead to dental loss. This study aimed to compare the amount of abrasion or loss of dentin based on pH, buffering, and concentration of HP and CA in commercial and experimental toothpastes after toothbrushing or immersion.

METHODS

Bovine dentin specimens were randomly assigned to nine solutions. The prepared solutions included two commercial toothpastes (whitening toothpaste [WT] with HP and CA; conventional toothpaste [CT] without HP and CA), reference slurry (RS), two CA solutions (1.92%, CAS1; 0.001%, CAS2), basic solution (7.16% sodium phosphate dibasic [SPDS]), CA phosphate buffer solution (3.58% SPDS and 0.96% CA [CAPB]), HP solution (4%, HPS), and distilled water (DW). Dentin specimens were performed in two treatments: one with only abrasion (10,000 brushings) and one with only immersion (1 h). After treatments, the amount of dentin loss and surface images were measured and observed using noncontact profilometry. Data were analyzed using an one-way analysis of variance and the Tukey test as a post hoc analysis (p < 0.05).

RESULTS

WT with pH 5.0 had lower dentin abrasion than CT and RS after brushing but had higher dentin loss than both after immersion. The dentin surfaces of CAS1, CAPB, and WT were damaged after immersion, whereas HPS, CAS2, CT, SPDS, RS, and DW remained intact after soaking. CAS2 and HPS, which had a pH of 5.0 like WT, did not significantly differ from those of DW after brushing.

CONCLUSIONS

WT containing HP and CA did not cause significant dentin abrasion but may cause additional dentin loss even without brushing. After brushing or immersion, the CA concentration may affect the dentin surface more than the HP concentration included in WT. The amount of abrasion or loss of dentin after brushing or soaking can vary based on the composition, concentration, and buffer in the solution, even if the pH of the solution is similar to pH 5.0.

Influence of the Amount of Toothpaste on Cleaning Efficacy: An In Vitro Study

OBJECTIVES

 The aim of this in vitro study was to test the influence of the amount of toothpaste on enamel cleaning efficacy.

MATERIALS AND METHODS

 The hydrated silica-based test toothpaste (radioactive dentin abrasion: 60.19 ± 1.35) contained all ingredients of a regular fluoride toothpaste. The cleaning efficacy of four different toothpaste amounts (1.00 g, 0.50 g [both "full length of brush"], 0.25 g ["pea-size"], and 0.125 g ["grain of rice-size"]) diluted in 1.00 mL water were each tested for different brushing times (10, 30, 60, 120, 180, and 300 seconds) using a standardized staining model on human molars with a brushing machine. Photographic documentation and colorimetric measurements were conducted, respectively, initially, after staining and after each brushing step. Colorimetric measurements were used to calculate the stain removal (in %).

STATISTICAL ANALYSIS

 Results were analyzed by one-way analysis of variance with post hoc Tukey test and Levene's test for analysis of homogeneity of variance. The level of significance α was set at ≤ 0.05.

RESULTS

 The cleaning efficacy decreased significantly when using smaller toothpaste amounts. Stain removal after 120 seconds brushing time was: 77.4 ± 5.0% (1.00 g toothpaste), 75.7 ± 3.4% (0.50 g toothpaste), 54.1 ± 6.7% (0.25 g toothpaste), and 48.2 ± 7.1% (0.125 g toothpaste), respectively.

CONCLUSION

 In this in vitro study the cleaning efficacy of a medium-abrasive, hydrated silica-based toothpaste was analyzed. Note that 1.00 g toothpaste showed for all brushing times a significantly higher cleaning efficacy than 0.25 g toothpaste and 0.125 g toothpaste.

Abrasion Behaviour of Different Charcoal Toothpastes When Using Electric Toothbrushes

OBJECTIVES

The purpose of this in vitro study was to compare the abrasion behaviour of different charcoal toothpastes when brushing with electric toothbrushes on human enamel.

MATERIALS AND METHODS

A self-designed brushing machine was built using six commercially available electric toothbrushes in abrasion chambers. Each chamber was constantly supplied with a toothpaste-water mix. Pieces of human enamel, which were embedded in PMMA, were brushed for 4 h. Before and after brushing, profilometer measurements were performed in order to determine the substance loss due to brushing.

RESULTS

The following calculated mean removal values (mean ± SD) were found: (4.6 ± 0.6) µm (Group C: Splat Blackwood), (3.2 ± 0.9) µm (Group D: Curaprox Black is White), (2.3 ± 0.7) µm (Group B: Sensodyne Pro Schmelz), (1.7 ± 0.6) µm (Group A: Water), (1.4 ± 0.6) µm (Group E: Prokudent Black Brilliant). A post hoc Tukey HSD test (p = 0.05) showed that the results for Group A/B/E, Group B/D and Group C each lie within subsets that differ statistically significantly from the other subsets.

CONCLUSIONS

Within the limitations of this in vitro study, it can be stated that some charcoal toothpastes lead to significantly higher abrasion on human enamel, when brushing with electric brushes.

CLINICAL RELEVANCE

As low-abrasion toothpaste is generally advisable, and some charcoal toothpastes should be viewed critically with regard to their abrasive properties.

In vitro abrasivity and chemical properties of charcoal-containing dentifrices

Objective

Charcoal-containing dentifrices are gaining popularity, but scientific information on their effect on oral health is scarce. This study investigated properties of dentifrices that may affect dentine abrasivity, as well as their ability to adsorb fluoride, their pH and the presence of harmful substances.

Materials and methods

The dentifrices NAO and COCO were subjected to the following analyses: abrasivity, expressed as mean abraded depth and relative dentin abrasivity (RDA), and surface roughness of extracted human molars (n = 30) after simulated brushing; fluoride adsorption measured as concentration change; pH measurements; detection of polycyclic aromatic hydrocarbons by gas chromatography–mass spectrometry. The products were compared to a reference dentifrice (Colgate^® MaxWhite), positive controls (ISO dentifrice slurry, activated charcoal for laboratory use) and a negative control (distilled water).

Results

The mean abraded depths of NAO and COCO were not different (p > .05), but higher than the reference dentifrice and the negative control (p < .05). The RDA values of NAO, COCO and the ISO dentifrice slurry were higher than the reference dentifrice value (p < .05) by up to 10 times. The dentine surface roughness was higher after brushing with NAO, COCO and ISO dentifrice slurry compared to distilled water (p < .05). No change in mean adsorbed fluoride concentration was observed after 24 h (p > .05). Both NAO and COCO were alkaline (pH > 7). Analysis of NAO revealed the presence of naphthalene (112.8 ± 2.0 ng/mL).

Conclusion

The charcoal-containing dentifrices were abrasive within acceptable limits set by ISO and did not adsorb fluoride. The presence of naphthalene in one product is a cause for concern.

Evaluating the Abrasivity of a Nanosized Eggshell-Titanium Dioxide on Tooth Enamel Using Atomic Force Microscopy

Objectives  This study aimed to evaluate nanosized eggshell–titanium dioxide (EB@TiO ² ) abrasiveness in comparison with calcium carbonate and hydrated silica-containing toothpaste.

Material and Methods  Thirty-five bovine tooth enamels were prepared, and specimens randomly assigned to a sample group of five ( n = 7), namely, Colgate regular, Colgate pro-relief, Sensodyne rapid relief, Sensodyne repair, and EB@TiO ₂ . Half of the enamel surface was brushed with each respective sample group, while the other half was covered with a tap.

Statistical Analysis  The mean roughness value (Ra) of the brushed and covered halves were measured using an atomic force microscope (AFM). To assess the surface morphology and changes, a scanning electron microscope (SEM) was performed. Using pair sample test and ANOVA, the Ra for the entire specimens were analyzed. A Bonferroni correction was used to identify the mean differences among the five groups (α=.05).

Results  The findings from this analysis show that all the tested toothpaste abraded the enamel significantly ( p < 0.05). The abrasive value contained in toothpaste comprising calcium carbonate was lower than the silica toothpaste hydrated.

Conclusion  Overall, Colgate regular had the lowest toothpaste abrasivity, followed by EB@TiO2, while Sensodyne rapid relief had the most enamel wear. The prominent feature of this study suggests that EB@TiO2 is suitable for oral use, as its abrasivity is comparable with calcium carbonate-containing toothpaste.

Morpho-Chemical Observations of Human Deciduous Teeth Enamel in Response to Biomimetic Toothpastes Treatment

Today, biomaterial research on biomimetic mineralization strategies represents a new challenge in the prevention and cure of enamel mineral loss on delicate deciduous teeth. Distinctive assumptions about the origin, the growth, and the functionalization on the biomimetic materials have been recently proposed by scientific research studies in evaluating the different clinical aspects of treating the deciduous tooth. Therefore, appropriate morpho-chemical observations on delivering specific biomaterials to enamel teeth is the most important factor for controlling biomineralization processes. Detailed morpho-chemical investigations of the treated enamel layer using three commercial toothpastes (Biorepair, F1400, and F500) were performed through variable pressure scanning electron microscopy (VP-SEM) and energy dispersive X-ray spectroscopy (EDS) on deciduous teeth in their native state. A new microscopy methodology allowed us to determine the behaviors of silicate, phosphate, and calcium contents from the early stage, as commercially available toothpastes, to the final stage of delivered diffusion, occurring within the enamel layer together with their penetration depth properties. The reported results represent a valuable background towards full comprehension of the role of organic-inorganic biomaterials for developing a controlled biomimetic toothpaste in biofluid media.

Baking soda as an abrasive in toothpastes: Mechanism of action and safety and effectiveness considerations

BACKGROUND

Toothpastes can be formulated with different abrasive systems, depending on their intended clinical application. This formulation potentially affects their effectiveness and safety and, therefore, requires proper understanding. In this article, the authors focused on abrasive aspects of toothpastes containing sodium bicarbonate (baking soda), which have gained considerable attention because of their low abrasivity and good compatibility, while providing clinical effectiveness (further detailed in the other articles of this special issue). The authors first appraised the role of toothpaste abrasivity on tooth wear, exploring some underlying processes and the existing methods to determine toothpaste abrasivity.

TYPES OF STUDIES REVIEWED

The authors reviewed the available data on the abrasivity of toothpastes containing baking soda and reported a summary of findings highlighting the clinical implications.

CONCLUSIONS

On the basis of the collected evidence, baking soda has an intrinsic low-abrasive nature because of its comparatively lower hardness in relation to enamel and dentin. Baking soda toothpastes also may contain other ingredients, which can increase their stain removal effectiveness and, consequently, abrasivity.

PRACTICAL IMPLICATIONS

Even those formulations have abrasivity well within the safety limit regulatory agencies have established and, therefore, can be considered safe.

The Influence of Suspension Containing Nanodiamonds on the Morphology of the Tooth Tissue Surface in Atomic Force Microscope Observations

Reduced friction and wear of materials after the use of the carbon nanomaterials including nanodiamonds (NDs) have been confirmed by several studies in material engineering. Mechanical cleaning of the tooth surface by brush bristles should leave as little tissue roughened as possible. Higher surface roughness increases the tissue's wear and encourages the redeposition of the bacteria and the colouring agents present in the diet. Therefore, we evaluated the tooth tissues' surface's morphological changes after brushing them with the NDs suspension. Ten human teeth were brushed with the NDs aqueous suspension. The surfaces were observed using an Atomic Force Microscope (AFM). We found that the nature of the tissue surface became milder and smoother. A number of selected profilometric parameters were compared before and after brushing. We observed that brushing with the suspension of NDs resulted in a significant reduction in the enamel and dentine's surface roughness both in the range of the average parameters (Ra; p-0,0019) and in the detailed parameters (Rsk; p-0,048 and Rku; p-0,036). We concluded that the NDs used in the oral hygiene applications have a potentially protective effect on the enamel and the dentine's surfaces.

Influence of the Extended Use of Desensitizing Toothpastes on Dentin Bonding, Microhardness and Roughness

The aim of this study was to evaluate the influence of an extended use of desensitizing toothpastes (DTs) on dentin bonding, microhardness and roughness. One hundred and twenty bovine incisor teeth were randomly divided into four groups: G1, distilled water (WATER); G2, Colgate Total 12 (CT12); G3, Colgate Sensitive Pro-Relief (CSPR); and G4, Sensodyne Repair ?αμπ; Protect (SRP). Dentin surfaces were etched with 17% EDTA and 2 years of simulated tooth brushing (20,000 cycles) was performed on their surfaces. Knoop microhardness, surface roughness and scanning electron microscopy (SEM) were performed before and after the simulated tooth brushing. For microshear bonding test, a 2-step self-etching adhesive system (Clearfil SE Bond) was used and 0.8 mm diameter composite resin (Filtek Z350 XT) cylinders were built. Microshear test was performed with an orthodontic wire and with a crosshead speed of 0.5 mm/min. The data were analyzed for: 1) bond strength (one-way ANOVA), 2) microhardness intra-group (Student's test) and inter-group (one-way ANOVA/Tukey's test) comparisons, 3) roughness intra-group (Student's test/Wilcoxon's test) and inter-group (Kruskal-Wallis/Student-Newman-Keuls test) comparisons. The extended use of both dentifrices (conventional and for sensitive teeth) did not affect the bond strength and produced a significant increase in microhardness and roughness of the dentin, except for the microhardness of the SRP group. The simulated tooth brushing technique with water produced an increase in roughness, without reducing significantly the dentin microhardness.

Influence of Surfactants and Fluoride against Enamel Erosion

This study investigated the effect of surfactants associated with sodium fluoride (NaF) on enamel erosion prevention, using an erosion-remineralization in vitro model. Sodium lauryl sulfate (SLS), polysorbate 20 (P20), and cocoamidopropyl betaine (CAPB) were tested, at concentrations of 1.0 and 1.5%, and associated or not with NaF (275 ppm). The control groups were distilled water and the NaF solution. Bovine enamel samples (n = 12) were prepared and submitted to a 5-day cycling model: acid challenge (0.3% citric acid, pH 2.6, 4×/day), human saliva (2 h, 4×/day), and the treatment solutions (2 min, 2×/day). The protective potential of the agents against initial erosion was assessed by microhardness and the surface loss by profilometry. Enamel surface wettability was determined by goniometry, protein adsorption was measured by spectroscopy (FTIR), and the KOH-soluble fluoride was quantified. Goniometry showed that SLS and CAPB increased enamel wettability. No differences were found among the surfactants regarding protein adsorption. Microhardness showed that SLS reduced NaF protection. P20 (1 and 1.5%) and CAPB 1.5% presented a protective effect, but lower than the NaF solution. Profilometry showed that CAPB protected enamel, but no agent associated with NaF promoted a higher protection than the NaF solution alone. KOH-soluble fluoride analysis showed that all surfactants reduced the fluoride adsorption on the enamel surface. Therefore, the surfactants tested (except for P20) changed the enamel surface energy. The SLS decreased the protective potential of NaF on initial erosion, but no tested agent interfered with the protective effect of NaF on enamel erosive wear.

Potential application of Bacillus subtilis SPB1 lipopeptides in toothpaste formulation

•

The application of a lipopeptide biosurfactant in a toothpaste formulation.

•

The investigation of the physicochemical properties and the cleaning ability of the formulated toothpaste.

•

The evaluation of the antimicrobial activity of the formulated toothpaste.

•

The follow-up of the formulated toothpaste stability.

Toothpaste is a gel dentifrice used with a toothbrush as an accessory to clean, keep and promote oral hygiene. The literature review suggests that there are many different formulations of toothpastes and that each of their individual components present specific functions. The concentration of the toothpaste ingredients must be appropriately chosen taking into account the purposes of the toothpaste. Biosurfactants are considered as suitable molecules for application in many formulations such as in toothpaste one. In the present work, two dentifrice formulations were investigated and their efficiencies were tested using chemical surfactant agent and lipopeptide biosurfactant isolated from Bacillus subtilis SPB1. The physicochemical properties were analyzed considering several tests mainly spreading ability, water activity, pH, foaming and cleaning tests. The obtained results indicated that the SPB1 biosurfactant was as efficient as the chemical surfactant confirming its potential utilization in toothpaste formulation compared to the commercial one. The evaluation of the antimicrobial activity of the formulated dentifrice was carried out against eight bacteria. The results demonstrated that the biosurfactant-based product exhibited an important antimicrobial activity, which was very effective against Enterobacter sp and Salmonella typhinirium.

Toothbrush abrasivity in a long-term simulation on human dentin depends on brushing mode and bristle arrangement

Objective

The aim of this study was to evaluate the susceptibility of dentin to brushing abrasion using four different toothbrushes (rotating-oscillating, sonic and two types of manual toothbrushes) with the same brushing forces.

Methods

Dentin samples (n = 72) were selected from 72 impacted third molars. Half of the surface of dentin samples was covered with an adhesive tape, creating a protected and a freely exposed area in the same specimen. Brushing was performed with either a: sonic (Sonicare PowerUp, Philips GmbH, Hamburg, Germany), b: oscillating-rotating (Oral B Vitality Precisions Clean, Procter & Gamble, Schwalbach am Taunus, Germany) or two different manual toothbrushes c: flat trim brush head toothbrush (Dr. Best: Original, Glaxo-Smith-Kline, Bühl, Germany) and d: rippled-shaped brush head toothbrush (Blend-a-Dent, Complete V-Interdental, Blend-a-med, Schwalbach, Germany) in a custom made automatic brushing machine. The brushing force was set to 2 N and a whitening toothpaste (RDA = 150) was used. The simulation period was performed over a calculated period to mimic a brushing behavior of two times a day brushing for eight years and six months. Dentin loss was quantitatively determined by profilometry and statistically analyzed by Wilcoxon and Mann-Whitney-U Test (p < 0.05).

Results

The mean (standard deviation) surface loss was 21.03 (±1.26) μm for the sonic toothbrush, 15.71 (±0.85) μm for the oscillating-rotating toothbrush, 6.13 (±1.24) μm for the manual toothbrush with flat trim brush head and 2.50 (±0.43) μm for the manual toothbrush with rippled-shaped brush head. Differences between all groups were statistically significant at p<0.05.

Conclusion

Using the same brushing force and a highly abrasive toothpaste, manual toothbrushes are significantly less abrasive compared to power toothbrushes for an 8.5—year simulation.

Effects of whitening dentifrice on yttria-stabilized tetragonal zirconia polycrystal surfaces after simulating brushing

STATEMENT OF PROBLEM

The changes that occur after brushing yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) are unknown. These changes may favor the retention of microorganisms and chemisorption of water, impairing its longevity.

OBJECTIVE

The purpose of this in vitro study was to evaluate the effects of a whitening dentifrice on Y-TZP surfaces after simulating 10 years of brushing.

MATERIAL AND METHODS

Seventy-two bar-shaped specimens (20×4×1.2 mm) were divided into 4 groups: storage in distilled water (SW, control), brushing with distilled water (BW), brushing with dentifrice (BD), and brushing with whitening dentifrice (BWD). Brushing was conducted using a linear brushing machine (878400 cycles, 0.98 N, soft toothbrush). The mean roughness (Ra) was analyzed with a profilometer and the superficial topography with scanning electron microscopy (SEM) at baseline and after treatment. Crystalline phases were characterized using x-ray diffraction. Baseline and posttreatment Ra were analyzed using the 1-way ANOVA and Tukey HSD multiple comparison test; the paired t test was used for intragroup comparison (all α=.05).

RESULTS

The Ra (μm) means (before/after treatment) were SW 0.28/0.28; BW 0.32/0.31; BD 0.28/0.36; BWD 0.30/0.20. No statistically significant difference was found for Ra at baseline (P=.108) than for posttreatment results (P<.001); the BD group had higher Ra values when compared with baseline (P=.019); the BWD group had the lowest values (P<.001). The BD surfaces showed pronounced scratches and detachment of the surface, while BWD showed smoother surfaces; similar crystallographic results among groups were observed.

CONCLUSIONS

Brushing Y-TZP with conventional dentifrice increased roughness, while brushing with whitening dentifrice reduced roughness. Neither dentifrice changed the crystallographic phases after brushing.

Influence of Bristle Stiffness of Manual Toothbrushes on Eroded and Sound Human Dentin--An In Vitro Study

Aim

The aim of this study was to determine the influence of manual toothbrushes with different bristle stiffness on the abrasivity on eroded and sound human dentin.

Materials and Methods

Dentin specimens were made from impacted third molars and attributed to three groups: erosion-abrasion (EA), abrasion (A) and erosion (E). The specimens from EA and E were treated with 1% citric acid (pH 2.3) for 1 min rinsed, and neutralized with artificial saliva for 15 min. This cycle was repeated five times. Thereafter, specimens from EA and A were treated with three toothbrushes types with different bristle stiffness (soft, medium, and hard) in a custom-made toothbrushing machine. The brushing was performed at a load of 3 N with a toothpaste slurry for 630 s. This procedure was repeated five times, in group EA after each erosion cycle. EA and A groups passed through five cycles with a total of 6300 strokes. The abrasivity was analyzed by contact-free profilometry. Kruskal-Wallis and Mann-Whitney U tests were performed for statistical analysis.

Results

With respect to bristle stiffness there was no statistically significant difference in dentin loss within the EA group. In group A, a statistically significantly higher dentin loss was found for the soft in comparison to the hard bristles. No statistically significant differences were measured between soft/medium and medium/hard toothbrushes. The amount of dentin loss from specimens in the EA group was significantly higher than in the A group.

Conclusions

Within the limitations of this study, the dentin loss in the Abrasion group was higher with soft bristles than with hard ones. This result might have an influence on the toothbrush recommendations for patients with non-carious cervical lesions.

Dentin abrasivity of various desensitizing toothpastes

Background

The aim of this study was to compare the abrasivity of various commercially available toothpastes that claim to reduce dentin hypersensitivity.

Methods

Dentin discs were prepared from 70 human extracted molars. The discs were etched with lemon juice for 5 min, and one half of the discs were covered with aluminum tape. Following this, they were brushed with 6 different toothpastes, simulating a total brushing time of 6 months. As a negative control, discs were brushed with tap water only. The toothpastes contained pro-arginine and calcium carbonate, strontium acetate, stannous fluoride, zinc carbonate and hydroxyapatite, new silica, or tetrapotassium pyrophosphate and hydroxyapatite. After brushing, the height differences between the control halves and the brushed halves were determined with a profilometer and statistically compared using a Mann–Whitney U test for independent variables.

Results

A significant difference (p < 0.001) in height difference between the controls and the toothpaste-treated samples was found in all cases, except for the stannous fluoride-containing toothpaste (p = 0.583). The highest abrasion was found in the toothpaste containing zinc carbonate and hydroxyapatite, and the lowest was found in the toothpaste containing pro-arginine and calcium carbonate.

Conclusions

Desensitizing toothpastes with different desensitizing ingredients have different levels of abrasivity, which may have a negative effect on their desensitizing abilities over a long period of time.

Choice of toothpaste for the elderly: an in vitro study

Hyposalivation and dental root exposure in the elderly are problems that require special oral care. In this context, the characteristics of certain toothpastes are of particular importance. Thus, the aim of this study was to evaluate the cytotoxicity and dentin wear caused by seven different toothpastes. For dentin wear analysis, 40 root dentin specimens were submitted to 20,000 brushing cycles with the different toothpastes and distilled water (control group-CG), using a brushing machine. Dentin surface loss (SL) was measured by contact profilometer. The cytotoxicity of each toothpaste was tested using cultured fibroblasts submitted to a cell-culture-conditioned medium. Fresh medium served as the control. Cell viability was assessed by MTT assay after 24 h of contact with the conditioned media. The data were analyzed statistically by ANOVA, followed by Tukey's test (p < 0.05). The SL of the CG was minimal and significantly lower than that of the Oral B Pro Health (OBPH) group (p < 0.05). All other groups presented SL in between that of the CG and the Oral B Pro Health OBPH group, except for the Sensodyne (SEN) group, which presented SL similar to that of CG (p = 0.05). The SEN group presented a percentage of viable cells similar to that of CG: between 60-89%. All the other toothpastes showed high cytotoxicity, with cell viability less than 50% of the CG. Considering study limitations, we concluded that only one of the seven tested toothpastes exhibited the most desirable toothpaste characteristics for the worldwide growing elderly population (e.g. low cytotoxicity and low-abrasive potential).

Characterization of Dentifrices Containing Desensitizing Agents, Triclosan or Whitening Agents: EDX and SEM Analysis

Dentifrices with different compositions are available on the market, but there is limited information about their properties. The aim of this in vitro study was to evaluate the physicochemical characteristics of 12 dentifrices divided into three categories, as containing desensitizing agents, Triclosan or whitening agents. Desiccation loss/residue analysis: 5 g of dentifrice was weighed five times for each group. pH analysis: 5 g of dentifrice were diluted in three parts of distilled water and analyzed using a digital potentiometer. Scanning electron microscopy (SEM): analysis of ashes, shape and size of the particles. Energy-dispersive x-ray spectroscopy (EDX): identification of the abrasive elements. Data were analyzed using ANOVA, Bonferroni post hoc test (α=0.05). Desiccation loss: 38.21% to 65.83%. Dentifrices containing Triclosan and desensitizing agents showed statistically significant differences among them (p<0.05). Whitening dentifrices showed statistically significant differences between Close-Up Whitening and Sensodyne Branqueador (44.72%, 65.83%, respectively). Most dentifrices presented neutral or basic pH. Different shape and size particles were observed in the SEM analysis. Abrasive elements were identified in the EDX. These results demonstrate that the evaluated dentifrices had different properties and their composition influences directly their characteristics, thus resulting in a more or less abrasive action on tooth surface. Knowing the characteristics of the dentifrices is important to indicate the ideal product for each case.

In vitro assessment of a toothpaste range specifically designed for children

OBJECTIVE

To evaluate the ability of a range of low abrasivity experimental toothpastes designed for use by children at different stages of their development (typically ages 0-2 years, 3-5 years and 6+ years) to promote fluoride uptake and remineralisation of artificial caries lesions.

METHODS

pH cycling study: demineralised human permanent enamel specimens were subjected to a daily pH cycling regime consisting of four 1-minute treatments with toothpaste slurries, a 4-hour acid challenge and remineralisation in pooled whole human saliva. Surface microhardness (SMH) was measured at baseline, 10 days and 20 days, and the fluoride content determined at 20 days. Enamel Fluoride Uptake (EFU): these studies were based on Method #40 described in the US Food and Drug Administration (FDA) testing procedures. Abrasivity: relative enamel abrasivity (REA) and relative dentine abrasivity (RDA) were measured using the Hefferren abrasivity test. Bioavailable fluoride: the bioavailable fluoride was determined for all experimental toothpastes from slurries of one part toothpaste plus 10 parts deionised water.

RESULTS

Enamel remineralisation measured by changes in SMH correlated with enamel fluoride content. A statistically significant fluoride dose response was observed for all toothpastes tested across all age groups (P < 0.05). The fluoride content of specimens in the pH cycling model correlated with the EFU testing results. The enamel and dentine abrasivities were low and the level of bioavailable fluoride was high for all experimental toothpastes.

CONCLUSION

A series of low abrasivity experimental toothpastes were developed which were effective at promoting fluoride uptake and remineralisation of artificial caries lesions.

The importance of measuring toothpaste abrasivity in both a quantitative and qualitative way

OBJECTIVE

To evaluate the relative abrasivity of different toothpastes and polishing pastes both qualitatively and quantitatively.

MATERIALS AND METHODS

Acrylic plates were exposed to brushing in a brushing machine with a toothpaste/water slurry for 1 and 6 h. Twelve different toothpastes were used and also four different polishing pastes. The results were evaluated using a profilometer after 1 and 6 h of brushing (corresponding to 2000 and 12 000 double strokes, respectively). A surface roughness value (Ra-value) and also a volume loss value were calculated from the profilometer measurements. These values were then correlated to each other. An unpaired t-test for the difference in the abrasion values between the toothpastes and the abrasion values over time was used.

RESULTS

The polishing paste RDA® 170 yielded higher Ra-values than RDA 250®, both after 1 and 6 h of brushing (1.01 ± 0.22 and 8.99 ± 1.55 compared to 0.63 ± 0.26 and 7.83 ± 5.89, respectively) as well as volume loss values (3.71 ± 0.17 and 20.20 ± 2.41 compared to 2.15 ± 1.41 and 14.79 ± 11.76, respectively), thus poor correlations between the RDA and Ra and Volume loss values were shown. Among the toothpastes, Apotekets® showed the highest Ra value after 1 h of brushing and Pepsodent® whitening after 6 h of brushing. Pepsodent® whitening also showed the highest volume loss values, both after 1 and 6 h of brushing.

CONCLUSION

This study emphasizes the importance of not only considering the RDA value, but also a roughness value, when describing the abrasivity of a toothpaste. Furthermore, it can be concluded that so called 'whitening' toothpastes do not necessarily have a higher abrasive effect than other toothpastes.

Scaffold-free microtissues: differences from monolayer cultures and their potential in bone tissue engineering

OBJECTIVES

Cell-based therapies for bone augmentation after tooth loss and for the treatment of periodontal defects improve healing defects. Usually, osteogenic cells or stem cells are cultivated in 2D primary cultures, before they are combined with scaffold materials, even though this means a loss of the endogenous 3D microenvironment for the cells. Moreover, the use of single-cell suspensions for the inoculation of scaffolds or for the direct application into an area of interest has the disadvantages of low initial cell numbers and susceptibility to unwanted cellular distribution, respectively.

MATERIALS AND METHODS

We addressed the question whether an alternative to monolayer cultures, namely 3D microtissues, has the potential to improve osteogenic tissue engineering and its clinical outcome.

RESULTS

By contrast, to monolayer cultures, osteogenic differentiation of 3D microtissues is enhanced by mimicking in vivo conditions. It seems that the osteogenic differentiation in microtissues is enhanced by strong integrin-extracellular matrix interaction and by stronger autocrine BMP2 signaling. Moreover, microtissues are less prone to wash out by body fluids and allow the precise administration of large cell numbers.

CONCLUSION

Microtissue cultures have closer characteristics with cells in vivo and their enhanced osteogenic differentiation makes scaffold-free microtissues a promising concept in osteogenic tissue engineering.

CLINICAL RELEVANCE

Microtissues are particularly suitable for tissue engineering because they improve seeding efficiency of biomaterials by increasing the cell load of a scaffold. This results in accelerated osteogenic tissue formation and could contribute to earlier implant stability in mandibular bone augmentation.

Scaffold-free microtissues: differences from monolayer cultures and their potential in bone tissue engineering

Objectives

The paper’s aim is to review dentin hypersensitivity (DHS), discussing pain mechanisms and aetiology.

Materials and methods

Literature was reviewed using search engines with MESH terms, DH pain mechanisms and aetiology (including abrasion, erosion and periodontal disease).

Results

The many hypotheses proposed for DHS attest to our lack of knowledge in understanding neurophysiologic mechanisms, the most widely accepted being the hydrodynamic theory. Dentin tubules must be patent from the oral environment to the pulp. Dentin exposure, usually at the cervical margin, is due to a variety of processes involving gingival recession or loss of enamel, predisposing factors being periodontal disease and treatment, limited alveolar bone, thin biotype, erosion and abrasion.

Conclusions

The current pain mechanism of DHS is thought to be the hydrodynamic theory. The initiation and progression of DHS are influenced by characteristics of the teeth and periodontium as well as the oral environment and external influences. Risk factors are numerous often acting synergistically and always influenced by individual susceptibility.

Clinical relevance

Whilst the pain mechanism of DHS is not well understood, clinicians need to be mindful of the aetiology and risk factors in order to manage patients’ pain and expectations and prevent further dentin exposure with subsequent sensitivity.

The use of a profilometer for both quantitative and qualitative measurements of toothpaste abrasivity

AIM

To evaluate the abrasivity of different toothpastes both quantitatively and qualitatively with a profilometer technique and to correlate these findings to the radioactive dentin abrasivity (RDA) value.

MATERIALS AND METHODS

Acrylic plates were exposed to brushing in a brushing machine with 11 different toothpastes. The results were evaluated using a profilometer. A surface roughness value (Ra-value), that is, a qualitative measurement, and also a volume value, that is, a quantitative measurement, were calculated from the profilometer results. These values were then correlated to each other and to the RDA-value. A comparison between RDA, Ra and volume measurements was performed using linear fitting procedure.

RESULTS

The results showed that the correlation between RDA and Ra measurements was low (R(2) = 0.04) and also that the correlation between RDA and volume measurements was low (R(2) = 0.00002). Correlation between Ra and abraded volume was high (R(2) = 0.87).

CONCLUSIONS

It is important to consider not only the RDA-value when evaluating toothpaste abrasivity. From the profilometer results both a quantitative (volume) and qualitative (roughness) measurement of the abrasivity of a toothpaste can be obtained.

Toothpaste detergents: a potential source of oral soft tissue damage?

OBJECTIVES

Toothpastes are thought to be of benefit to cleaning teeth but may also have the potential for soft tissue damage at least on the cellular level by inclusion of detergents in their formulation. The aim of this study was to observe the in vitro response of oral mucosa like cells to toothpaste detergents.

METHODS

TERT-1 keratinocytes were exposed to varying concentrations of the detergents Adinol, Sodium Lauryl Sulphate, Tego Betain and Pluronic as well as PBS and culture medium. After 2-min exposure, cells were washed and incubated in fresh medium for 24 h. Cell death was then spectrophotometrically measured using an MTT assay.

RESULTS

Except for Pluronic, cell viability was markedly reduced for all detergents at all increasing concentrations when compared to the positive medium control. Cells treated with Pluronic were stimulated compared to medium alone.

CONCLUSIONS

These in vitro data suggest that some detergents may have the potential to cause soft tissue damage in the mouth. Although in vivo, saliva may neutralize such effects. The results for Pluronic suggest a possible oxidative stress response that bears further study.