Toothpaste Abrasivity Research Articles

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

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. 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. 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). 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.

Dental casting alloys behaviour during power toothbrushing with toothpastes of various abrasivities. Part II: corrosion and ion release

The purpose of this study was to evaluate the long term effect of abrasivity of toothpastes normally used over the corrosion behavior and ion release of the different dental casting alloys. Three dental casting alloys (Ni-Cr, Co-Cr and commercially pure Ti) were studied. Four specimens of each material were immersed, brushed without paste or brushed with one of four toothpastes of different Relative Dentine Abrasivity (RDA 50, 52, 80, and 114). An electric toothbrush with a load of 250 g was used for 420 min. Corrosion behavior was determined by means a potenciostat with high sensitivity and the ion release determined by Inductively Coupled Plasma-Mass Spectrometry. Two-way ANOVA and non-parametric tests were used to detect significant differences. Titanium specimens exhibited the best corrosion behavior after and before the toothbrushed, being the worst of the three alloys the Cr-Ni. Titanium oxide produced spontaneously on the Ti surface is the main cause of the high corrosion resistance of the material. However, the eutectoid of the CrNi with chemical composition between different phases produces pitting on the phases boundaries with an important decrease of the corrosion resistance. Besides, the CrNi produces high values of the Ni and Cr release. Slight increment in roughness were observed after toothbrushing and depended on the material but not on the toothpaste used. The increase of the microhardness (residual stresses) provokes a decrease of the corrosion resistance and an increase of the ion release.

Dental casting alloys behaviour during power toothbrushing with toothpastes with various abrasivities. Part I: wear behavior

The purpose of this study was to evaluate the long term effect of abrasivity of toothpastes normally used over the surface and mechanical properties of dental casting alloys. Three dental casting alloys (Ni-Cr, Co-Cr, c.p. Ti) and one ceramic were chosen. Four specimens of each material were immersed in artificial saliva, brushed without or with one of four toothpastes of different Relative Dentine Abrasivity (RDA 50, 52, 80, and 114). An electric toothbrush with a load of 250 g was used for 420 min. Mass loss was determined by difference in weight, microhardness and surface roughness were also measured. Two-way ANOVA and non-parametric tests were used to detect significant differences. Titanium specimens (478 microg/cm(2)) exhibited the most mass loss, whereas ceramic (282 microg/cm(2)) and Co-Cr (262 microg/cm(2)) exhibited the least. However, ceramic demonstrated the most volume loss (0.239 mm(3)). The abrasivity effect of the toothpaste correlated with the RDA values. Slight variations in microhardness were observed after toothbrushing and depended on the material but not on the toothpaste used. Material surfaces were slightly smoothed by toothbrushing but no significant differences were detected. Dental casting alloys and ceramic are susceptible to abrasion by brushing with an electric toothbrush depending on the RDA value of the toothpaste. Variations in microhardness and surface roughness were not clinically relevant.

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.

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.

Control of brushing variables for the in vitro assessment of toothpaste abrasivity using a novel laboratory model

Objectives Design and construct a tooth-brushing simulator incorporating control of brushing variables including brushing force, speed and temperature, thereby facilitating greater understanding of their importance in toothpaste abrasion testing methodologies. Methods A thermostatable orbital shaker was selected as a base unit and 16- and 24-specimen brushing rigs were constructed to fit inside, consisting of: a square bath partitioned horizontally to provide brushing channels, specimen holders for 25 mm diameter mounted specimens to fit the brushing channels and individually weighted brushing arms, able to support four toothbrush holders suspended over the brushing channels. Brush head holders consisted of individually weighted blocks of Delrin, or PTFE onto which toothbrush heads were fixed. Investigating effects of key design criteria involved measuring abrasion depths of polished human enamel and dentine. Results The brushing simulator demonstrated good reproducibility of abrasion on enamel and dentine across consecutive brushing procedures. Varying brushing parameters had a significant impact on wear results: increased brushing force demonstrated a trend towards increased wear, with increased reproducibility for greater abrasion levels, highlighting the importance of achieving sufficient wear to optimise accuracy; increasing brushing temperature demonstrated increased enamel abrasion for silica and calcium carbonate systems, which may be related to slurry viscosities and particle suspension; varying brushing speed showed a small effect on abrasion of enamel at lower brushing speed, which may indicate the importance of maintenance of the abrasive in suspension. Conclusions Adjusting key brushing variables significantly affected wear behaviour. The brushing simulator design provides a valuable model system for in vitro assessment of toothpaste abrasivity and the influence of variables in a controlled manner. Control of these variables will allow more reproducible study of in vitro tooth wear processes.

Surface texture and composition of titanium brushed with toothpaste slurries of different pHs

Objectives This in vitro study characterized the surface texture and composition of titanium brushed with toothpaste slurries of different pHs, and thereby elucidated mechanochemical interactions between the metal and abrasive material in dentifrice. Methods Two fluoride-free toothpastes, which contained crystalline CaHPO 4·2H 2O and amorphous SiO 2 particles as abrasive, were mixed with acidic buffers to provide slurries of pH 6.8 and 4.8. Specimens were cast from CP Ti, mirror-polished, and then toothbrushed at 120 strokes/min for 350,400 strokes under a load of 2.45 N. Specimen surfaces were characterized by means of SPM and EPMA. The obtained data were compared with the already reported results of water-diluted alkaline slurries. SPM data of each paste were analyzed using one-way ANOVA, followed by post hoc Tukey test. Results Irrespective of toothpaste, neutral slurries, as with alkaline slurries, yielded a chemically altered surface with rough texture, whereas acidic slurries formed a chemically clean surface with relatively smooth texture. Mechanochemical polishing effect might be mainly responsible for the cleanness and smoothness. Significance Acidic slurry-induced smooth surface may minimize plaque formation. However, the augmentation of released titanium ions may be adverse to the human body. For evaluation of toothpaste abrasion effects on titanium, paste slurry pH should be taken into account.

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

To measure in vitro the abrasion of dentine by toothpaste detergents and abrasives alone and combined. Detergents used were tego betain, sodium lauryl sulphate (SLS), adinol and pluronic diluted to 1% w/v. Abrasives were three artificial silicas, tixosil 73 and 123 and Zeodent 113, and calcium carbonate used at 2.5% w/v. Flat human dentine specimens were brushed with aqueous detergent solutions or abrasive slurries, detergent abrasive slurries and water for 20,000 brush strokes. Dentine loss was measured by non-contacting profilometry at 10,000 and 20,000 strokes. Silica particle size distribution was measured by laser deflection. Loss of dentine occurred with all detergents, abrasives and detergent abrasion combinations, but was not linear with number of brush strokes. Water appeared to remove the smear layer only, but all detergents exceeded the predicted smear layer thickness. The silica abrasives differed in abrasion properties despite similar particle size distribution. Different detergents modulated the abrasives actions in mainly positive or mainly negative directions. Detergents appear able to attack the dentine surface to produce wear. Abrasives vary considerably in wear produced under similar conditions. Detergents modulate the effect of abrasives in a way that may reflect the rheological properties of the mixture.

Toothpaste abrasivity: an introduction to the symposium

Toothpaste abrasivity: an introduction to the symposium

The protective nature of the salivary pellicle

All solid substrata exposed to the oral environment are rapidly covered by a layer of adsorbed salivary proteins, the acquired pellicle. The physiological role of the pellicle is lubrication and protection of the underlying surface. This review focuses on the protective properties of the salivary pellicle. Several in vitro as well as in vivo investigations indicate that the adsorbed protein layer on the one hand has the potential to reduce the extent of enamel demineralisation upon acid challenge. On the other hand pellicle could be dissolved and removed from the enamel surface due to the acid exposure. However, pellicle reformation starts rapidly. Conflicting data have been published concerning the importance of pellicle formation time (‘maturation’) with regard to its protective function. Recently published studies indicate that pellicle formation time is probably of less importance for the pellicle’s protective properties under in vivo conditions than supposed from the in vitro experiments. Since pellicle formation is useful for the protection of the enamel surface, it should be also considered in daily oral hygiene. Tooth brushing with and without toothpaste causes reduction of the pellicle’s thickness. However, the pellicle layer is not completely removed from the enamel surface after brushing procedures. Therefore the presence of a pellicle will be an important modifying factor when considering tooth wear models. In situ tooth wear models offer the opportunity to measure toothpaste abrasion effects in the presence of a pellicle film.

The use of acrylic to compare the abrasivitand stain removal properties of toothpastes

The aim of this study was to compare the abrasivity and stain removal properties of toothpastes using acrylic. Acrylic blocks were exposed to 2·5 × 10 4 and 5·0 × 10 4 brush strokes with a number of toothpastes. Abrasion measurements were made using a surfometer. Percentage stain removal with time was recorded from specimens stained by chlorhexidine and tea soaking. Pre- and post-treatment optical densities were recorded spectrophotometrically. Products were applied to specimens as slurries alone or with brushing. Depth of abrasion was ⩽ 10 μm for most toothpastes (5 × 10 4 strokes). For two desensitising toothpastes the depth reached > 40 μm. Stain removal was dependant on the duration of brushing, but at 1 min., ranged from 97% to 50% for toothpastes and 45% for a brush and water. Slurries of toothpaste also variably removed stain; effects at 1 min. ranged from 90% to levels similar to water, namely 5%. It is concluded that the model is a simple and reproducible method to compare oral hygiene products and allows chemical stain removal properties to be ascertained and divorced from abrasion and chemical erosion.

Disruption of Complement‐Mediated Reactions by Insoluble Dentifrice Ingredients

It has been strongly suggested that the complement system plays a critical role in the pathological processes occurring in periodontal disease. Because individuals with this common disease are often instructed to brush their teeth more often and for longer periods of time, several commercial toothpastes were tested for their effects on complement-mediated reactions. In this study, six of the nine toothpastes tested activated the classical complement pathway, leading to C3 cleavage, as determined by crossed immunoelectrophoresis. The activating ingredients were contained in the insoluble fraction of the toothpastes. Of the toothpaste abrasives, Ca++ pyrophosphate was determined to have C3-converting activity. One of the toothpastes, which contains a particular type of amorphous silica abrasive, appeared to bind both native C3 and its conversion products. In general, disruption of complement-mediated functions in affected tissues could alter local immunological responses and interfere with healing. The in vitro studies described here suggest a need for clinical studies to ascertain the in vivo influences of dentifrice ingredients on complement-mediated reactions in periodontal disease.

Toothpaste abrasive requirements to control naturally stained pellicle. The relation of cleaning power to toothpaste abrasivity.

Toothpaste abrasivity should be sufficiently high to give effective cleaning without causing mechanical damage to tooth tissue. A clinical trial carried out to measure the cleaning power of calcium carbonate toothpastes of different abrasivity is described; cleaning power is then related to in vitro dentine abrasivity measurements. These findings are used to derive an expression specifying the toothpaste cleaning power which ensures that a chosen low and cosmetically acceptable level of stain is not exceeded providing a consistent daily brushing routine is adhered to.

Experimental foreign body reactions to toothpaste abrasives.

Some clinical oral foreign body reactions have been reviewed. The testing of the foreign body potential of substances used as abrasives in toothpastes has shown a number to be capable of this. The clinical implications are briefly discussed. The initial studies were conducted when the author was on the faculty of the School of Dentistry, University of Birmingham, England.