Abrasivity of toothpastes. An in vitro study of toothpastes marketed in Norway

Buffer Solution Reduces Acidic Toothpaste Abrasivity Measured in Standardized Tests

It has been speculated that the diluent used to test toothpaste abrasivity in standard tests may have an impact on their results, especially in the context of acidic toothpastes. This study tested whether an acidic toothpaste is indeed more abrasive than a neutral counterpart of otherwise identical composition, and whether this increased abrasivity is prevented by a buffered solution simulating saliva. Two experimental toothpastes of identical composition yet different pH (7.0 vs. 5.0) were prepared using standard ingredients. Subsequently, they were tested in standard absolute dentin abrasion and relative dentin abrasivity (RDA) experiments. To prepare slurries for these tests, deionized water as recommended by the International Organization for Standardization (ISO 11609:2017) was used, or a buffer solution containing bicarbonate and phosphate. The pH in these slurries was assessed and compared to the pH obtained in oral slurries of healthy individuals. Results showed that a significant (one-way ANOVA, p < 0.05) increase in mean absolute dentin abrasion and RDA values by 35 and 14%, respectively, was obtained when water was used as the diluent in conjunction with the acidic toothpaste as compared to the buffer solution. This was not the case with the neutral toothpaste. This result was explained by the finding that the buffer solution neutralized the pH in experimental slurries of the acidic toothpaste, while deionized water was unable to elevate the pH of the acidic toothpaste. That toothpaste was also neutralized in oral slurries. It was concluded that indeed the current ISO standard may result in a systematic overestimation of acidic toothpaste abrasivity.

Noncarious Cervical Lesions and Their Association With Toothbrushing Practices: In Vivo Evaluation

Knowledge of the characteristics and etiologies of noncarious cervical lesions assists dentists in selecting an appropriate treatment and improving the prognosis.

The measurement in vitro of dentine abrasion by toothpastes

OBJECTIVES

To investigate the in vitro dentine wear after tooth brushing with a range of nine toothpastes.

METHODS

70 bovine dentine blocks (aproximately 1 cm long) were used. Specimens were brushed in vitro with toothpastes with a range of abrasive. All the specimens were submitted to 10,000 brushing cycles with a 200g load. Initial and final weight and profile data were obtained using an analytical scale and a profile projector respectively.

RESULTS

Significant differences between the test products were found (p < 0.05). The mean dentine wear ranged from 0.039 to 0.006g and 0.502 to 0.185mm, with the highest wear for the whitening toothpastes.

CONCLUSIONS

This study demonstrated that the type of toothpaste abrasive can contribute to dentine wear.

A critical review of non-carious cervical (wear) lesions and the role of abfraction, erosion, and abrasion

The terms 'abfraction' and 'abrasion' describe the cause of lesions found along the cervical margins of teeth. Erosion, abrasion, and attrition have all been associated with their formation. Early research suggested that the cause of the V-shaped lesion was excessive horizontal toothbrushing. Abfraction is another possible etiology and involves occlusal stress, producing cervical cracks that predispose the surface to erosion and abrasion. This article critically reviews the literature on abrasion, erosion, and abrasion, and abfraction. The references were obtained by a MEDLINE search in March, 2005, and from this, hand searches were undertaken. From the literature, there is little evidence, apart from laboratory studies, to indicate that abfraction exists other than as a hypothetical component of cervical wear.

Abrasion of eroded root dentine brushed with different toothpastes

This study evaluated the surface roughness change and wear provided by different dentifrices on root dentine previously exposed to erosive challenges. According to a randomized complete block design, 150 slabs of bovine root dentine (6 x 3 x 2 mm) were ground flat and polished. In an area of 4 x 3 mm on the dentine surface, specimens were submitted to five erosive/abrasive events, each one composed by: exposure to Sprite Diet or distilled water for 5 min, then to a remineralizing solution for 1 min, and simulation of 5,000 brushing strokes. Four dentifrices--regular (RE), baking soda (BS), whitening (WT) and tartar control (TC)--and distilled water (CO), used as control, were compared. Final texture and the wear depth were evaluated using a profilometer. ANOVA did not show significant interaction, indicating that the effect of dentifrices on both surface roughness change and wear did not depend on whether or not the dentine was eroded ( p>0.05). There was no difference between abrasion of eroded and sound dentine. The Tukey's test revealed that WT, BS and TC provided the highest increase in surface roughness differing from RE and CO. TC yielded the deepest wear of root dentine, whereas RE and CO, the shallowest. No significant difference in wear among BS, TC and WT were observed. Within the limitations of this study, the data showed that abrasion of both eroded and sound root dentine was dependent on the dentifrice used.

Estudo in vitro da abrasividade de dentifrícios

O objetivo do presente estudo é avaliar a abrasividade de 15 dentifrícios, utilizando o aparelho Einlehner AT 1000. Uma solução contendo 50 g de cada creme dental mais 800 ml de água destilada era colocada no referido aparelho, que promovia 174.000 rotações da haste metálica, com um cilindro descartável de borracha, sobre uma tela de cobre pesada previamente (P1), por 100 minutos. Com o término da operação, a tela era lavada, seca e novamente pesada (P2). Através da equação: (P1-P2) ÷ 3,07 x 10-4 encontrava-se o número de gramas/metro2. Cada dentifrício foi testado 3 vezes e o valor final apresentado é a média dos 3 testes. Adicionalmente foram investigados o pH e o teor de sólidos das diferentes marcas. Os resultados mostraram que os dentifrícios possuem uma grande variação no grau de abrasão. As 3 marcas mais abrasivas foram: Close Up com flúor, Colgate Antitártaro e Oral B Dentes e Gengivas, as duas primeiras com dióxido de silício. As 3 marcas menos abrasivas foram: Colgate M.F.P. com cálcio, Gessy com flúor e Signal com flúor, todas com carbonato de cálcio. Os dentifrícios Close Up com flúor, Kolynos Ação Total e Oral B Dentes e Gengivas apresentaram um pH abaixo de 7, que pode indicar um possível efeito erosivo, associado à abrasão. Novas pesquisas são necessárias para comparar esses resultados com cremes dentais internacionais.

Mercury release from dental amalgams: an in vitro study under controlled chewing and brushing in an artificial mouth

The release of mercury vapor from class I amalgam restorations prepared in human molar teeth was studied during chewing simulations in an artificial mouth of a bi-axial servo-hydraulic mechanical test system. So that the total mercury released from the restoration over a fixed time could be determined, a closed chamber surrounded the envelope of chewing motion. In addition, the influence of sampling frequency on mercury release was corrected by the use of different sampling frequencies over a fixed time interval of mercury release measurement and extrapolation to zero sampling time. Thus, a combination of a closed environment and an extrapolation method to determine the mercury release under continuous sampling was used to determine the mercury released under normal breathing conditions. The measured mercury release rate data were used to calculate the potential daily mercury dose in a patient due to a single amalgam restoration, following the method previously outlined by Berglund. The mercury release from both a conventional and a high-copper amalgam was evaluated at different age intervals after the restoration was placed in the teeth. The results show that while the age of the amalgam and the amalgam type influence the extent of mercury release during the initial non-steady-state conditions, the steady-state value of mercury daily dose due to a single amalgam filling is 0.03 micrograms/day, which is well below the calculated threshold-limiting value (TLV) of 82.29 micrograms/day considered dangerous for occupational exposure in the United States.

In vitro abrasion of two acrylic veneers

OBJECTIVES

The purpose of this investigation was to compare the degree of abrasion in vitro of two acrylic veneers and dental enamel using a dentifrice with and without fluoride.

METHODS

Ten specimens of each of the two acrylics and enamel were embedded in resin, and eventually polished to 1 micron with diamond paste. Specimens were brushed in a brushing machine with 10,000 double strokes using a dentifrice (Solidox, A/S Denofa) with and without fluoride. The abrasion was evaluated by the naked eye, by photographs and measured by means of profilometer.

RESULTS

One of the polymer materials (Dentacolor, Kulzer) showed a significantly higher resistance to abrasion than the other (Biodent, DeTrey), irrespective of fluoride treatment. Brushing with or without fluoride revealed no significant difference in degree of abrasion between the two acrylic materials. Dentacolor showed significantly higher abrasion resistance than enamel, whereas Biodent did not. There was no significant difference in the degree of abrasion of enamel using dentifrice with or without fluoride.

SIGNIFICANCE

Abrasion of acrylic veneering material differed greatly between brands, but did not seem to be influenced by the fluoride in toothpaste.

Stress-induced cervical lesions

The increasing occurrence of dental lesions at the cervical surfaces requires more knowledge of the causes of the process. Acidic and abrasive mechanisms have clearly been documented as causes but the stress theory by Lee and Eakle is still controversial. This report describes several incidences of possible stress-induced lesions according to the characteristics described by Lee and Eakle. The occurrences of subgingival lesions lend credence to the stress-induction theory by exclusion of other superimposing etiologic factors. With the current concepts, a perceptive approach to the treatment of cervical lesions can be executed.

The effect of hygiene instruments on dentin surfaces: scanning electron microscopic observations

The present study consists of two separate parts. The first section is an in vitro evaluation of the relative abrasiveness of some hygiene instrumentations commonly used during maintenance therapy. In the second section, one of the instruments, a recently developed plastic tip for use on a sonic scaler, was examined for its ability to remove dental plaque from root surface specimens instead for 5 weeks in the oral cavities of dogs. The in vitro study was performed on recently obtained dentin specimens where a ridge had been machined parallel to the long axis of the tooth. The sonic scaler fitted with the plastic tip gave considerably less removal of dentin and a smoother dentin surface than the curet, the rubber cup with polishing paste, or the sonic scaler with an ordinary metal tip. These findings further demonstrated that the plastic tip was able to efficiently remove 5-week old dental plaque from experimental root surface areas within a time frame of 5 seconds. The new plastic tip may be valuable in maintenance therapy giving less risks for iatrogenic effects on the root surfaces than other debridement methods.

Influence of polishing procedures on sonic scaling root surface roughness

The present in vitro study aimed to evaluate the efficacy of various polishing procedures in reducing root roughness caused by sonic scaling. Proximal root surface areas of extracted, formalin-stored teeth were scaled in a bucco-lingual direction by a sonic scaler. The resulting roughness was measured along the direction of scaling and perpendicular to that direction by a profilometer. The specimens were then split into two groups. Group 1 was polished by an air-powder polishing instrument followed by a rotating rubber cup and chalk; Group 2 was polished by pumice followed by chalk. Root roughness (Ra) was recorded for each step in the procedures. The measurements revealed lower Ra values when the stylus of the profilometer was running perpendicular to the scaling direction, and a weak negative correlation was found when scaling time and Ra values were compared. In both groups Ra values were significantly reduced at each step of the polishing procedures and the terminal result was similar for the groups. Pumice and air-powder polishing gave a similar reduction of the sonic scaling roughness.