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Acta Odontológica Latinoamericana

versión On-line ISSN 1852-4834

Acta odontol. latinoam. vol.25 no.1 Buenos Aires abr. 2012

 

ARTÍCULOS ORIGINALES

Analysis of surface roughness of human enamel exposed to bleaching agent and submitted to brushing

 

Raquel Pachaly, Roselaine T. Pozzobon

Post-Graduation Program in Dental Sciences, Federal University of Santa Maria Rio Grande do Sul– Brazil.

CORRESPONDENCE Dr. Raquel Pachaly Av. Fernando Ferrari, 1070/301 CEP 97050-800 Santa Maria RS – Brazil e-mail: raquel-pachaly@uol.com.br


ABSTRACT

The aim of this study was to assess in vitro the surface roughness (Ra) of human enamel exposed or not exposed to the action of a bleaching agent containing 10% carbamide peroxide (CP) after brushing with different dentifrices. Ninety-six human enamel specimens were divided into 2 groups: GI – exposed to the action of 10% CP; GII – not exposed. These were subdivided into 4 brushing subgroups: (CEW) Close-Up Extra Whitening, (CUB) Colgate Ultra Branco, (CCP) Crest Cavity Protection and (DW) Deionized Water. The specimens from Group GI were exposed to 10% CP for 6 hours/14 days and those from Group GII were stored in artificial saliva for 14 days. Then they were submitted to 35.600 brushing cycles. Ra was measured before and after brushing. Ra difference was compared by two-way ANOVA. Ra was compared between subgroups using ANOVA and Tukey's test. Ra was compared between groups using T-test (á=0.05). Final and initial Ra were compared by Paired t-test; using SPSS (15.0). Two-way ANOVA difference in the outcome revealed that the use of bleaching agent did not affect the difference in Ra (p = 0.45). Brushing significantly influenced the difference in Ra (p <0.001), but the interaction between the two factors was not significant (p = 0.20). Among the brushing subgroups, a significant increase in Ra was observed for Subgroup CEW – GI: Rai 0.691 (0.112)a, Raf 0.993 (0.264)a; Raf-Rai: 0.303a(43.7%) – G2: Rai 0.794(0.167)a, Raf 1.006(0.488)a; Raf-Rai: 0.212a (26.7%) with a statistical difference for Subgroup CUB – GI: Rai 0.639 (0.163)a, Raf 0.506 (0.113)b; Raf-Rai: -0.133b(-20.8%) – GII: Rai 0.647(0.166)a, Raf 0.472b(0.260); Raf-Rai: -0.134b(-0.27%). Regardless of whether or not the enamel had been exposed to 10% CP, Ra values varied according to the abrasives in the composition of the different dentifrices.

Key words: Dental enamel; Bleaching agent; Dentifrices.

RESUMO

Análise da rugosidade superficial do esmalte humano exposto ao agente clareador e submetido à escovação

O objetivo deste trabalho foi avaliar in vitro a rugosidade superficial média (Ra) do esmalte humano exposto ou não à ação de agente clareador com peróxido de carbamida (PC)10% após escovação com diferentes dentifrícios. Foram utilizados 96 espécimes de esmalte divididos em 2 grupos: GI- exposto à ação de gel clareador e GII- não exposto à ação de gel clareador e subdivididos em 8 subgrupos de escovação: (CEW) Close-Up Extra Whitening, (CUB) Colgate Ultra Branco, (CCP) Crest Cavity Protection e (AD) Água Deionizada. Os espécimes do grupo GI foram submetidos ao tratamento clareador com PC10% por 6h/14 dias; os do grupo GII ficaram armazenados em saliva artificial por 14 dias. Decorrido este período, os grupos foram submetidos à 35.600 ciclos em máquina de escovação mecânica que corresponde a 2 anos e meio de escovação normal, utilizando escova Oral-B. A Ra foi medida antes e depois da escovação com um Rugosímetro Mitutoyo SJ 201P. A diferença da Ra foi comparada pela ANOVA bifatorial. A Ra dos subgrupos foi comparada pela ANOVA e pelo Teste de Tukey. A Ra dos grupos foi comparada pelo Teste- T(á=0.05) e a comparação entre a Raf x Rai foi realizada pelo Teste-T Pareado. O software utilizado foi o SPSS 15.0 (Statistical Package for Social Sciences). Os resultados de ANOVA bifatorial do desfecho diferença de rugosidade revelaram que o fator grupo não afetou a diferença de Ra (p=0.45). O fator subgrupo influenciou significamente a diferença de Ra (p<0.001), porém a interação entre ambos fatores não foi significativa (p=0.20). Entre os subgrupos de escovação pode-se observar um aumento significativo da rugosidade para o subgrupo CEW ( Rai 0.691; Raf 0.993) com diferença estatística para o subgrupo CUB( Rai 0.639; Raf 0.506). Esses resultados estão relacionados com os diferentes abrasivos presentes na compo - sição dos dentifrícios uma vez que a abrasividade do dentifrício depende da dureza, forma, tamanho, amplitude da distribuição e concentração das partículas.

Palavras Chave: Esmalte Dental; Agentes Clareadores; Dentifrícios.


 

INTRODUCTION

Over the last few years, patients have been increasingly concerned about dental esthetics because they wish to have healthy, attractive teeth, for which they use cosmetic products directly available on the market or seek clinical treatments in aesthetic dentistry. Tooth bleaching is a popular treatment, which is widely advertised in the media and affordable to patients. As a result, new products with alleged bleaching action are constantly released on the market, claiming to improve the appearance of the smile when it has color alteration.
Tooth color may be altered by the combination of extrinsic and intrinsic staining substances that come into contact with the tooth structure. Since tooth bleaching is a conservative treatment, it is considered as a first choice among alternative treatments in aesthetic dentistry. Extrinsic stains are usually the result of surface precipitation of coloring agents and pigments in the diet (black tea, coffee, red wine) or habits (smoking) on the acquired film of enamel1-3, whereas intrinsic stains are determined by the layer of dentin underlying the enamel surface, which becomes discolored as a result of fluorosis, trauma, use of antibiotics, systemic conditions and natural aging of teeth3,4. To remove these stains, teeth can be bleached with bleaching agents and/or bleaching dentifrices, which have different action mechanisms. The most popular dental bleaching method is the supervised home technique which uses 10% carbamide peroxide as a bleaching agent to remove both intrinsic and extrinsic stains. This bleaching agent is very unstable, and when it comes into contact with the tissues and saliva, it dissociates into 3% hydrogen peroxide and 7% urea. Urea degrades to ammonia and carbon dioxide, while hydrogen peroxide breaks down easily into water and oxygen, penetrating into the enamel and dentin, promoting dental bleaching5 However, the effects of bleaching agents on dental structures are still controversial because some studies have shown no significant change 6-12, while others conclude that bleaching agents cause significant morphological changes, which range from changes in the mineral content to changes in surface roughness and micro hardness of the dental structure 13-17. Despite these controversies, it is known that if changes occur in the surface roughness of the structure, they may contribute to the appearance of extrinsic stains and plaque accumulation, which is reflected by mineral loss and inflammation of the gingival tissues18.
Another option that has become popular is the use of dentifrices with supposed bleaching action, which may be purchased at supermarkets and drugstores. It is known that these bleaching dentifrices in some way promote dental bleaching by removing and/or controlling extrinsic stains on the tooth surface through the abrasion process1,2. The following abrasive agents are typically found in these bleaching dentifrices: hydrated silica, calcium carbonate, dicalcium phosphate dihydrate (DCPD), calcium pyrophosphate, alumina, sodium bicarbonate and perlite3,4,19. The abrasiveness of dentifrices depends on particle hardness, shape, size, distribution range and concentration20-23. However, this abrasiveness needs to be moderate in order not to cause damage to hard and soft tissues24. From the above information and consultation of current scientific literature, it can be seen that there is little information about the effect of dentifrices on the surface roughness of human enamel, exposed or not to the action of home-use bleaching agents. Thus, this study aimed to evaluate in vitro the surface roughness (Ra) of human enamel exposed or not the action of the bleaching agent carbamide peroxide (CP) 10%, after brushing with different dentifrices.

MATERIAL AND METHODS

Experimental Design (Table 1): The factor under study was the action of two bleaching dentifrices - Close-Up Extra Whitening (CEW) and Colgate Ultra Branco (CUB), a conventional dentifrice - Crest Cavity Protection (CCP) - positive control, and Deionized Water (DW) - negative control – on the average surface roughness of human enamel either exposed to the action of a bleaching agent containing 10% carbamide peroxide (CP) – Opalescence (Ultradent Product Inc, Salt Lake City, Lot:C129), or not. We used 96 human enamel specimens from 48 healthy third molars, recently extracted for orthodontic reasons, showing no surface changes due to trauma during the extraction, obtained from the Human Permanent Tooth Bank at UFSM.

Table 1: Dentifrices assessed and their abrasive systems.

They were divided randomly into 2 groups: Group I – exposed to the action of a bleaching agent with 10% CP and Group II – not exposed. Each of these groups were subdivided into 4 brushing subgroups according to the dentifrice or deionized water used (control) (Table 2). The response variable was Ra, determined through a readout made with a roughness meter.

Table 2: Division of groups studied.

Selection and preparation of the enamel specimens
Forty-eight extracted healthy human third molars were selected, from which 96 dental enamel specimens were obtained. The teeth were cleaned with Gracey type curettes (Newmar Surgical Instruments- São Paulo - SP - Brazil), pumice stone and water, applied with a Robinson brush (Microdont - São Paulo - SP- Brazil). After cleaning, the teeth were submitted to a sterilization process in a humid medium. The teeth were stored in saline solution at 5°C until the beginning of the study. To prepare the specimens, the sites for the longitudinal and cross sections were marked with graphite on the vestibular and/or lingual surfaces of the crowns. Sections measuring 5 x 5 x 2mm were cut from the flattest area of the crown (middle third), using a double-faced diamond disk (KG Sorensen- Cotia - SP- Brazil) driven by a handpiece at low speed with water irrigation. After this, the specimens were flattened with 600- grit abrasive paper on the side composed of dentin so that all the specimens had the same thickness. After preparation, the specimens were measured using a digital pachymeter. They were polished with 6-8 µm extra-thin polishing paste (Diamond- FGM - Joinvile - SC- Brazil), applied with a sandpaper disk and stored in deionized water up to the time they would or would not be bleached.

Exposure to a bleaching agent, or not
The specimens in Group I (n= 48) were exposed to the action of 10% CP gel (Opalescence). A template corresponding to one drop of the bleaching gel was made so that all the specimens received the same amount of bleaching agent. The gel was applied on a glass slide, superimposed on the template. The specimens were placed on the bleaching gel and stored in plastic containers, covered with gauze dampened in deionized water, and remained in an oven at 37ºC for 6 hours, for 14 days15. Then they were washed with deionized water for 10 seconds and stored in artificial saliva at 37ºC, simulating a complete homebleaching treatment9,15. The specimens from Group II (n = 48) were stored in individual containers, duly identified, in artificial saliva at 37ºC for 14 days during bleaching treatment.

Brushing procedure
To perform brushing, a brushing device was devised by the Department of Operative Dentistry of the Dentistry Course at UFSM (Fig, 1) and designed and developed at the Mechanical Engineering course at UFSM. The machine consisted of a motor that produced back-and-forth movements of 10 arms by means of pulleys, onto which the toothbrushes were fixed. Oral-B Indicator Plus 40 (Gillete do Brasil Ltda, Manaus-AM) soft-bristle toothbrushes were used. The machine was set up to run a 3.8 cm horizontal course on the tooth, applying a 200g axial load. A cycle was understood to be a complete back-andforth movement of the toothbrush. In each brushing procedure, 10 toothbrushes were used, which were changed halfway through the complete brushing cycle in order to avoid the influence of toothbrush bristle wear on the result. For brushing, the enamel specimens were fixed in acrylic resin at the base of the brushing machine, so that they would be prominent, allowing better action of the toothbrush bristles.


Fig. 1: Mechanical brushing machine UFSM.

The base where the specimens were fixed to the machine was turned 90º in the middle of the cycle so that brushing could be performed in two directions. The application of the Dentifrice was applied in the form of a suspension of toothpaste in deionized water in the proportion of 1:125. The paste formed by toothpaste diluted in deionized water was injected manually every 1 minute. After the tests were concluded, the specimens were removed from the brushing machine and immediately washed with jets of deionized water and stored in artificial saliva at 37ºC.

Surface Roughness Analysis
Average surface roughness (Ra) of each enamel specimen was analyzed using a digital roughness meter (Mitutoyo Surftest SJ-201P). To perform the roughness readout, the diamond point of the roughness meter would run on the specimens at a constant speed of 0.25mm/s and force of 4mN. The cut-off value was adjusted to act at 0.25 µm and surface roughness was characterized by the arithmetical average of surface peak and valley heights found within a central line along the area assessed (Ra), in micrometers (µm). Five readings were performed on each specimen in different directions. The average of these readings was used for the statistical analysis. The initial Ra reading (Rai) was performed 24 hours after exposure (Group I) to the bleaching agent, or not (Group II). 24 hours after the Rai reading, the brushing procedures began and at the end of this stage, the specimens were stored for 24 hours in artificial saliva and the final Ra reading (Raf) was performed.

Statistical Analysis
Ra difference was compared by two-way ANOVA. Subgroup Ra was compared by ANOVA and Tukey's test. Group Ra was compared by T-test (á=0.05), Comparison between final versus initial Ra was done by Paired t-test

Scanning Electronic Microscopy (SEM)
With the purpose of visualizing and illustrating the results, a SEM of the specimens of each subgroup chosen randomly after brushing was performed. The microscopies that were most representative of the results were selected, since it was not the aim of this study to perform SEM analysis. To perform SEM, the selected enamel specimens were dehydrated and submitted to the metallization process with gold-palladium alloy. The images were captured at 500X magnification and observed under a Scanning Electronic Microscope JEOL A110 (Figs. 2-9).


Fig. 2
: Image obtained by SEM of the surface micromorphology of enamel exposed (E) to the action of the bleaching agent and brushed with CEW dentifrice.


Fig. 3
: Image obtained by SEM of the surface micromorphology of enamel exposed (E) to the action of the bleaching agent and brushed with CUB dentifrice.


Fig. 4
: Image obtained by SEM of the surface micromorphology of enamel exposed (E) to the action of the bleaching agent and brushed with CCP dentifrice.


Fig. 5
: Image obtained by SEM of the surface micromorphology of enamel exposed (E) to the action of the bleaching agent and brushed with DW.


Fig. 6
: Image obtained by SEM of the surface micromorphology of enamel not exposed (NE) to the action of the bleaching agent and brushed with CEW dentifrice.


Fig. 7
: Image obtained by SEM of the surface micromorphology of enamel not exposed (NE) to the action of the bleaching agent and brushed with CUB dentifrice.


Fig. 8
: Image obtained by SEM of the surface micromorphology of enamel not exposed (NE) to the action of the bleaching agent and brushed with CCP dentifrice.


Fig. 9
: Image obtained by SEM of the surface micromorphology of enamel not exposed (NE) to the action of the bleaching agent and brushed with DW.

RESULTS

Two-way ANOVA difference in the outcome revealed that the Ra factor Group (exposure or not to bleaching agent) did not affect the difference in Ra (F= 0.57; p = 0.45). The subgroup factor (brushing) significantly influenced the difference in Ra (F= 12.37; p <0.001), but the interaction between the two factors was not significant (F=1.54; p = 0.20).
Table 3 shows the differences in Rai and Raf in Groups I and II for each brushing subgroup. In both groups, there was a statistically significant increase in Ra for the CEW dentifrice subgroup. For the other brushing subgroups, no statistically significant alteration in Ra was observed. For Groups I and II, within each brushing subgroup, no statistically significant difference in Ra was found (capital letters on the horizontal line). No statistically significant difference in Rai was found among the brushing subgroups. Similar results were observed both for Raf and difference in Ra (lowercase letters in the vertical column). CEW is statistically different from CUB; in turn, CCP and DW did not differ statistically from the other brushing subgroups. In the images obtained by SEM (Figs. 2-9) it was possible to observe alterations in surface micromorphology of enamel exposed, or not, to the action of the bleaching agent and brushed with different dentifrices and deionized water, which were consistent with the results of this study. The results can be observed in differences of the surface micromorphology of the specimens shown in Figs. 2 and 3 of GI (rough appearance) and in Figs. 6 and 7 of GII (smoothness / polishing characteristics).

Table 3: Mean surface roughness values (Ra) for Groups I and II, before (Rai) and after (Raf) brushing with each subgroup.

DISCUSSION

This study tested the effect of brushing with different dentifrices on average surface roughness of human enamel either exposed or not exposed to the action of a bleaching agent with 10% carbamide peroxide. Statistical analysis of the values obtained for Ra showed that the behavior of the different brushing subgroups was the same. Whether or not the enamel had been exposed to the bleaching agent did not influence the difference in Ra obtained after the action of the different dentifrices. Therefore, the performance of each brushing subgroup will be discussed separately. It was found that the different dentifrice formulations had different effects on the surface roughness of enamel. This could be related to the different abrasives present in their compositions, which is supported by the study by Pickles22, who reported that abrasiveness of the dentifrice depends on particle hardness, shape, size, distribution range and concentration. Camargo et al. 21 demonstrated that the larger the size of the abrasive particles, the greater is the abrasiveness of the dentifrice. However, different types of abrasives with similar particle sizes present different abrasiveness values. According to these authors, this difference in abrasiveness may be attributed to the difference in hardness of the abrasive particles.
With regard to the shape of the abrasive particles, Ashmore et al.26 observed that dentifrices that contain calcium carbonate in their composition, in more regular oval or rhombohedral shape, were less abrasive than those with more irregular aragonite particles. Davis and Winter27 showed that dentifrices that contain fine particles, such as calcium carbonate and silica, are less abrasive than those with rougher particles. Two dentifrices with alleged bleaching action, Closeup Extra Whitening (CEW) and Colgate Ultra Branco (CUB) and one regular dentifrice, Crest Cavity Protection (CCP) were assessed. The regular dentifrice CCP has only silica as an abrasive component, while the other dentifrices contain different abrasives in their compositions. The dentifrice CUB has calcium carbonate, aluminum, bicarbonate of soda and sodium silicate as abrasives, and in its composition the dentifrice CEW has abrasives of the calcium carbonate, perlite and silica type. Perlite is a natural volcanic glass with flat glassshaped particles and sharp cutting edges. While in use under load, the abrasive particles are broken down and the cutting edges become rounded and rhomboid. The perlite particles thus remain parallel to the tooth surface, reducing the potential for scratches on the surface and increasing their polishing capacity. The use of perlite as an abrasive is common in prophylactic pastes, which are excellent stain removers, combined with good polishing properties and low abrasiveness28,29. Table 3 shows that there was a statistically significant increase in enamel Ra only for the brushing subgroup CEW, possibly due to the presence of the perlite abra
sive in its composition. For Lutz et al.28, the increase in enamel roughness, after polishing with prophylactic pastes containing perlite can be explained by the performance of the particle through the process of rounding by disintegration or change in the direction of the abrasive particles under load Kuroiwa et al.30, showed that abrasive dentifrices caused light abrasion of enamel and microwear, which may change the surface layer of enamel, exposing the enamel prisms and creating a "new" surface, and this new surface could be related to the increase in roughness for CEW in this study.
Table 4
shows that CEW dentifrice with perlite did not differ statistically from CCP with silica and DW, which partly agrees with the findings of Joiner et al.31 and Joiner et al.32, who found that for the level of enamel wear, there was no statistical difference between dentifrices with perlite and silica after twelve weeks in situ with ex vivo brushing, while in this study, brushing time was equivalent to two and a half years. The study by Lutz et al.28, who observed that there was no statistical difference in roughness between the prophylactic paste with perlite and water, also matches the results of this study. Moreover, according to Table 4, it can be verified that the brushing subgroup CEW showed an increase in Ra, which differed statistically from CUB. This difference may be related to the wear dynamics of perlite, previously mentioned by Lutz et al. 28, as well as distinct Mohs hardness values of the abrasive particles in their different combinations. If the enamel hardness is taken into consideration (Mohs hardness 5 to 8)33, and compared to the composition of different dentifrices, it is observed that the CUB dentifrice has alumina- type abrasive in its composition, which is considered an abrasive particle with a high Mohs hardness value of 9.25. Other abrasives such as calcium carbonate, sodium bicarbonate and sodium silicate, derived from silica, have Mohs hardness ranging from 2.5 to 520, while the CEW dentifrice has abrasives such as calcium carbonate, with Mohs hardness of 3, silica and perlite with Mohs hardness from 5.5 to 729, closer to that of enamel. It can be assumed that the combination of different abrasives in the composition of dentifrices, with different Mohs hardness values, may have contributed to the findings of this study. According to Wülkinitz 34, the mixture of different abrasives may result in different patterns of cleaning/abrasion, differently from when they are used individually. Furthermore, the addition of polishing abrasives such as alumina, present in CUB, with other abrasives, generates an increase in cleaning power. According to Meyers et al. 19, some abrasives are capable of producing a highly polished, smooth surface, but when doing so, they cause a large amount of dental loss. Thus, both a polished surface and a rough surface may be a sign of a worn tooth surface, which could be observed in this study when the enamel was exposed to the action of CUB and CEW dentifrices, respectively.

Table 4: Comparison of the values of Rai, Raf and respective Ra differences between each brushing subgroup in Groups I and II.

In this study, it was also found that abrasion can be caused by other factors not related to the dentifrices, which were mentioned by Newbrun20, such as the hardness of the toothbrush bristles and the pressure applied and the frequency of brushing, since the subgroup brushed with deionized water was statistically similar to subgroups brushed with dentifrices. Because of this, these factors were standardized by applying a 200g axial load to simulate the force used during oral hygiene procedures24,25. A rev-counter recorded 35.600 cycles, for 160 minutes, corresponding to 2 ½ years of normal brushing. The corresponding brushing time is based on Joiner et al. 35, who reported that each tooth surface was brushed for 5 seconds twice a day. Considering the methodology applied, the results of this study indicated that regardless of whether or not the enamel had been exposed to bleaching agent for home use with 10% carbamide peroxide, the performance observed in the different brushing subgroups resulted in different Ra values. Moreover, it may observed that the type, shape, size and hardness of the abrasive particles are fundamental for the correct choice of dentifrice, but the information present on the packages of these products indicate only the abrasive present in the formula. This reinforces the need for further studies on the composition of the dentifrices, so that professionals can recommend the rational use of dentifrices according to the specific needs of each patient.

ACKNOWLEDEGEMENT

The authors are grateful to Coordenadoria de Aperfeiçoamento de pessoal de nível superior (CAPES) for encouraging the development of this work through a Stock Master.

REFERENCES

1. Watts A, Addy M. Tooth discolouration and staining: a review of the literature. Br Dent J 2001;190:309-316.         [ Links ]

2. Philpotts CJ, Weader E, Joiner A. The measurement in vitro of enamel and dentine wear by toothpastes of different abrasivity. Int Dent J 2005;55:183-187.         [ Links ]

3. Joiner A. Review of the extrinsic stain removal and enamel/ dentine abrasion by a calcium carbonate and perlite containing whitening toothpaste. Int Dent J 2006;56:175-180.         [ Links ]

4. Collins LZ, Naeeni M, Schäfer F, Brignoli C, Schiavi A, Roberts J, Colgan P. The effect of a calcium carbonate/perlite toothpaste on the removal of extrinsic tooth stain in two weeks. Int Dent J 2005;55:179-182.         [ Links ]

5. Haywood VB, Heymann HO. Nightguard vital bleaching: how safe is it? Quintessence Int 1991;22:515-523.         [ Links ]

6. White DJ, Kozak KM, Zoladz JR, Duschner HJ, Götz H. Effects of tooth-whitening gels on enamel and dentin ultrastructure -a confocal laser scanning microscopy pilot study. Compend Contin Educ Dent Suppl 2000;29:29-34.         [ Links ]

7. Lopes GC, Bonissoni L, Baratieri LN, Vieira LC, Monteiro S Jr. Effect of bleaching agents on the hardness and morphology of enamel. J Esthet Restor Dent 2002;14:24-30.         [ Links ]

8. White DJ, Kozak KM, Zoladz JR, Duschner H, Götz H. Peroxide interactions with hard tissues: effects on surface hardness and surface/subsurface ultrastructural properties. Compend Contin Educ Dent 2002;23:42-48.         [ Links ]

9. Cobankara FK, Unlü N, Altinöz HC, Füsun O. Effect of home breaching agents on the roughness and surface morphology of human enamel and dentine. Int Dent J 2004; 54:211-218.         [ Links ]

10. Moraes RR, Marimon JL, Schneider LF, Correr Sobrinho L, Camacho GB, Bueno M. Carbamide peroxide bleaching agents: effects on surface roughness of enamel, composite and porcelain. Clin Oral Investig 2006;10:23-28.         [ Links ]

11. Joiner A. Review of the effects of peroxide on enamel and dentine properties. J Dent 2007;35:889-896.         [ Links ]

12. Maia E, Baratieri LN, Caldeira de Andrada MA, Monteiro S Jr, Vieira LC.The influence of two home-applied bleaching agents on enamel microhardness: an in situ study. J Dent 2008;36:2-7.         [ Links ]

13. Ben-Amar A, Liberman R, Gorfil C, Bernstein Y. Effect of mouthguard bleaching on enamel surface. Am J Dent 1995; 8:29-32.         [ Links ]

14. Smidt A, Weller D, Roman I, Gedalia I. Effect of bleaching agents on microhardness and surface morphology of tooth enamel. Am J Dent 1998;11:83-85.         [ Links ]

15. Pinto CF, Oliveira R, Cavalli V, Giannini M. Peroxide bleaching agent effects on enamel surface microhardness, roughness and morphology. Braz Oral Res 2004;8:306-311.         [ Links ]

16. Efeoglu N, Wood D, Efeoglu C. Microcomputerised tomography evaluation of 10% carbamide peroxide applied to enamel. J Dent 2005;33:561-567.         [ Links ]

17. Markovic L, Jordan RA, Lakota N, Gaengler P. Micromorphology of enamel surface after vital tooth bleaching. J Endod 2007;33:607-610.         [ Links ]

18. Hosoya N, Honda K, Iino F, Arai T. Changes in enamel surface roughness and adhesion of Streptococcus mutans to enamel after vital bleaching. J Dent 2003;31:543-548.         [ Links ]

19. Meyers IA, McQueen MJ, Harbrod D, Seymour GJ The surface effect of dentifrices. Aust Dent J 2000;45:118-124.         [ Links ]

20. Newbrun E. The use of sodium bicarbonate in oral hygiene products and practice. Compend Contin Educ Dent Suppl 1997;18:2-7.         [ Links ]

21. Camargo IMC, Saiki M, Vasconcellos MBA. Abrasiveness evaluation of silica and calcium carbonate used in the production of dentifrices. J Cosmet Sci 2001;52:163-167.         [ Links ]

22. Pickles MJ. Tooth wear. In: Duckworth RM, The teeth and their environment. Basel, Karger, 2006;19:86-104.

23. Nogués L, Martinez-Gomis J, Molina C, Peraire M, Salsench J, Sevilla P, Gil FJ. Dental casting alloys behavior during power toothbrushing with toothpaste with various abrasivities. Part I: wear behavior. J Mater Sci Mater Med 2008;19:3041-3048.         [ Links ]

24. Lima DA, Silva AL, Aguiar FH, Liporoni PC, Munin E, Ambrosano GM, Lovadino JR. In vitro assessment of the effectiveness of whitening dentifrices for the removal of extrinsic tooth stains. Braz Oral Res 2008;22:106-111.         [ Links ]

25. Azevedo AM, Panzeri H, Prado CJ, De-Mello JD, Soares CJ, Fernandes-Neto AJ. Assessment in vitro of brushing on dental surface roughness alteration by laser interferometry. Braz Oral Res 2008;22:11-17.         [ Links ]

26. Ashmore H, Van Abbé NJ, Wilson SJ. The measurement in vitro of dentine abrasion by toothpaste. Br Dent J 1972; 133:60-66.         [ Links ]

27. Davis WB, Winter PJ. Measurement in vitro of enamel abrasion by dentifrice. J Dent Res 1976;55:970-75.         [ Links ]

28. Lutz F, Sener B, Imfeld T, Barbakow F, Schüpbach P. Selfadjusting abrasiveness: a new technology for prophylaxis pastes. Quintessence Int 1993;24:53-63.         [ Links ]

29. Lutz F, Sener B, Imfeld T, Barbakow F, Schüpbach P. Comparison of the efficacy of prophylaxis pastes with conventional abrasives or a new self-adjusting abrasive. Quintessence Int 1993;24:193-201.         [ Links ]

30. Kuroiwa M, Kodaka T, Kuroiwa M. Microstructural changes of human enamel surfaces by brushing with and without dentifrice containing abrasive. Caries Res 1993; 27:1-8.         [ Links ]

31. Joiner A, Jones NM, Raven SJ. Investigation of factors influencing stain formation utilizing an in situ model. Adv Dent Res 1995;9:471-476.         [ Links ]

32. Joiner A, Pickles MJ, Lynch S, Cox TF. The measurement of enamel wear by four toothpastes. Int Dent J 2008;58:23-28.         [ Links ]

33. Lutz F, Imfeld T. Advances in abrasive technology-prophylaxis pastes. Compend Contin Educ Dent 2002;23:61-68.         [ Links ]

34. Wülknitz P. Cleaning power and abrasivity of European toothpaste. Adv Dent Res 1997;11:576-579.         [ Links ]

35. Joiner A, Weader E, Cox TF. The measurement of enamel wear of two toothpastes. Oral Health Prev Dent 2004;2: 383-388.         [ Links ]

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