Microhardness and surface roughness of Biodentine exposed to mouthwashes.

Aim: This study evaluates Vickers microhardness and surface roughness in Biodentine cement (M1) and glass-ionomer cement Fuji IX (M2), both immersed in mouthwash. Materials and
Methods: Fifty-four samples were randomly distributed in distilled water (S1), Listerine Cool Mint (S2), and Colgate Plax (S3). Each sample was put in a flask with mouthwash for 2 min, under vibration, twice a day for 21 days. Microhardness and surface roughness were assessed at 48 h (T0), 7 days (T1), 14 days (T2), and 21 days (T3).
Results: For roughness: time (T), solution (S) and material (M), TxM, and SxM and for microhardness: M, TxS, TxM, and SxM were statistically significant. T3, M1, M1T3, and M1S1 presented the highest surface roughness. M2, M1T0, M1T1, M1T2, M1S1, and M1S2 presented higher microhardness.
Conclusion: Biodentine showed higher surface roughness for T1, T2, and T3 and higher microhardness for T0, T1, and T2 against Fuji IX. Biodentine presented higher microhardness independently of solution. Copyright:

INTRODUCTION

Temporary restorative materials are widely used in clinical practice and they are expected to properly seal treated areas. For a proper selection of this material, it is necessary to take into account its ability to withstand the effect of the various factors that act on the oral cavity and to maintain its physical and mechanical properties for a period of 21 days.[1]

Glass-ionomer cement (GIC) are routinely employed as temporary restorative materials and present a level of adhesion to dental tissue that contributes to a proper marginal seal and, consequently, to the longevity of the restoration. Moreover, GIC present the additional benefit of continuous release of fluorine with excellent biocompatibility, characteristics that make them frequent suitable choices.[23]

Biodentine™ (Septodont, Saint-Maur, France) is presented as a dental substitute due to its mechanical properties. The main composition of its powder is tricalcium silicate (Ca3SiO5), zirconium oxide, and calcium carbonate. The liquid is a mixture of water, calcium chloride, and a water-soluble polymer.[4] This material is indicated for dentine substitution in direct and indirect capping, pulpotomies, furcation lesions and root perforations, reabsorption treatments, and temporary restorations for posterior teeth.[5]

Since its market launch, most studies evaluated properties related to its application in endodontic lesions, such as cytotoxicity, solubility, radiopacity, and microstructure union resistance.[678910] Regarding these properties, Biodentine exhibits good workability, biocompatibility, and bacteriostatic properties.[11]

Nevertheless, there are studies of its use as a temporary restorative material regarding its endurance time within the cavity, surface characteristics due to abrasion,[5] surface roughness, and microhardness compared against other cement in several experimental settings.[681213]

Surface properties, such as teeth and material surface roughness and microhardness, play a fundamental role in quality of temporary fillings.[14] Surface biodegradation resulting from exposure to chemical solutions, such as oral mouthwashes, can affect these properties.[15] It should be considered that mouthwashes are routinely used by patients due to their anti-inflammatory and antiseptic properties.[16]

These solutions vary in their composition and can damage the surface of restorative materials due to low pH and alcohol in its composition.[17] Even though there are studies on their effects on several restorative materials, the subject is still controversial.[18] The continuous arrival of new alternatives is driven by a constant search for more suitable materials with better physical, mechanical, chemical, and biological properties.

There are few studies in the literature related to Biodentine™ as a temporary filling material, as well as to the effect of mouthwash on roughness and microhardness. In light of this situation, the objective of this study was to evaluate the effect of these hygienic agents in surface roughness and microhardness, comparing Biodentine™ to other GIC for temporary fillings for a period of 21 days.

MATERIALS AND METHODS

The factors studied were restorative materials: Biodentine and the Fuji IX GIC, solution: distilled water (control), Listerine® Cool Mint, and Colgate Plax Ice Infinity, and time: 48 h, 7 days, 14 days, and 21 days. To analyze surface roughness and microhardness, 54 test samples were organized in two groups, one group per filling material, with 27 samples each. Each group was randomly subdivided (n = 9) and assigned a solution for immersion.

Preparation of test samples

Following manufacturer specifications, the two filling materials: Biodentine™ (Septodont, Saint Maur Des Fosses, France) and Fuji IX (GC Corporation, Tokyo, Japan), were used to prepare 6-mm-diameter, 2-mm-height test samples in a Teflon matrix. Afterward, these samples were put on a glass surface inside a polyester matrix and then, after a 24-h stand-by period, polished with Sof-Lex (3M) discs.

All samples were kept at 100% relative humidity and 37°C ± 1°C for the duration of the experimental phase, only being taken out of the stove to be immersed in the 3 proposed solutions and when measurements were taken at 48 h and 7, 14, and 21 days.

One by one, samples were immersed in an 8-mL flask containing its assigned solution [Table 1] for 1 min, under vibration (cast vibrator used: Vibramaxx Gold Line-Essence Dental VH, Araraquara, Sao Paulo), twice a day for 21 days.[18]

Table 1

Mean surface roughness for the interaction material (M) × time (T) and material (M) × solution (S)

	M1 (BIO)	M2 (GIG)
T0	0.70 (±0.03) bA	0.62 (±0.03) aA
T1	0.85 (±0.03) bA	0.64 (±0.03) aB
T2	0.83 (±0.03) bA	0.63 (±0.03) aB
T3	1.10 (±0.03) aA	0.73 (±0.03) aB
S1	1.03 (±0.03) aA	0.60 (±0.03) aB
S2	0.81 (±0.03) bA	0.69 (±0.03) aB
S3	0.78 (±0.03) bA	0.67 (±0.03) aB

Lowercase letters for columns/uppercase letters for lines

Surface roughness measurement

A SJ-201 P/M rugosimeter (Mitutoyo, Tokyo, Japan) was used. A distance of 0.8 × 3 μm was previously determined and standardized. Three readings were taken each time, registering the arithmetic mean as the accepted value.

Microhardness measurement

An HMV-2000 microhardness meter with a Vickers-type pyramidal diamond penetrator (Shimadzu Corporation, Japan) was used, with 100-g weight, applied for 30 seconds. For each sample, three readings were taken, registering the arithmetic mean as the accepted value.

Statistical analysis

Kolmogorov–Smirnov and Shapiro–Wilk tests confirmed the data distribution normality. Afterward, data were analyzed using analysis of variance and a complementary Tukey's test (P ≤ 0.05). Analysis was performed using the Assistat (7.7 beta) Software Package.

RESULTS

Statistically significant difference was found for roughness, regarding the factors time (P < 0.01), solution (P < 0.05), and material (P < 0.01) when analyzed separately. Also for material × time (P < 0.01) and material × solution (P < 0.01) interactions.

The highest mean roughness values were found at material × time [Table 1] and material × solution [Table 1] interactions, M1 (Biodentine) after 21 days (T3). While M2 (GIC) showed no significant difference at all experimental periods (T0, T1, T2, and T3), where the smaller mean values were observed from T1 to T3 and when the immersion solution was water, confirming when analyzed in isolation.

When immersed in water, M1 showed higher mean values than in S1 and S2, both statistically equals. No differences were found for M2 regarding the immersion solutions [Table 1].

It was statistically significant for microhardness: the material factor (P < 0.01) and for the interactions: solution × time, material × time, and material × solution (0.01 ≤ P < 0.05). Materials immersed in S2 showed lower mean microhardness values after 14 days.

For material × time interaction, M1 presented similar results at all times. M2 at T0, T1, and T3 was also statistically equal. In contrast, M1 showed the highest microhardness at 48 h, 7 days, and 14 days than M2. While at 21 days, no difference was found between M1 and M2 [Table 2]. Finally, for material × solution interaction, M1 showed no difference on its microhardness at any solution. Whereas M2 presented differences between S1 and S3 (S3 > S1). When immersed in S1 or S2, M1 presented the highest microhardness values than M2. However, M1 and M2 mean values were similar when immersed in S3 [Table 2].

Table 2

Mean microhardness for the interaction solution (S) × time (T), interaction material (M) × time (T), and interaction material (M) × solution (S)

	S1	S2	S3
T0	60.95 (±2.61) aA	57.36 (±2.61) abA	56.05 (±2.61) aA
T1	55.32 (±2.61) aA	60.58 (±2.61) abA	61.00 (±2.61) aA
T2	55.66 (±2.61) aA	54.09 (±2.61) bA	55.06 (±2.61) aA
T3	54.31 (±2.61) aB	62.37 (±2.61) aA	60.92 (±2.61) aAB
	M1	M2
T0	62.33 (±1.74) aA	53.91 (±1.74) abB
T1	61.51 (±1.74) aA	56.43 (±1.74) aB
T2	60.62 (±1.74) aA	49.19 (±1.74) bB
T3	60.29 (±1.74) aA	58.11 (±1.74) aA
	M1	M2
S1	61.59 (±1.51) aA	51.53 (±1.51) bB
S2	62.86 (±1.51) aA	54.34 (±1.51) abB
S3	59.15 (±1.51) aA	57.37 (±1.51) aA

Lowercase letters for columns/uppercase letters for lines

DISCUSSION

The success of the restoration depends not only on choices made during execution but also on the correct indication. The restorative material chosen plays an important role in determining for how long the procedure fulfills its purpose. This selection should be made considering the aggressive environment of the oral cavity, taking into account all the agents that may have effects on it. Among these, chemical agents found in food and oral mouthwash, physical agents, such as temperature and colorants, and mechanical agents, such as masticatory forces and other tensions due to parafunctional habits.[19] Although the materials of this study, Biodentine and glass ionomer, are indicated for temporary restorations,[5] which represents a short stay in the oral cavity, they must have properties that ensure tooth protection in treatment and gingival health. Thus, surface roughness and microhardness are important properties for these materials.

After an analysis of surface roughness data, the interaction between material and time influences the surface roughness. Biodentine™, at 21 days, presents the highest mean surface roughness compared to the times in 48 h, 7 days, and 14 days. On the other hand, GIC maintained its properties in the same time period. This is probably due to the exposition time that may favor an increase of solubility. Comparing both materials, at its first 48 h, no statistical difference was found for roughness. However, from 7 to 21 days of immersion, it was verified that Biodentine™ presented higher mean roughness when compared to the Fuji IX GIC. This could be related to their composition. Biodentine™ contains tricalcium silicate, calcium carbonate, and zirconium oxide in its powder and calcium chloride in its liquid.[20] According to Vivan et al.,[21] it releases calcium ions that contribute to an increase in solubility when compared to materials that do not release ions. This is said to result in the disintegration of the material, which could be a determining factor for an increase in roughness.

Regarding the interaction of material and solution, results were statistically significant. It was observed that Biodentine™ presented higher surface roughness when immersed in distilled water when compared to Colgate Plax Ice Infinity and Listerine® Cool Mint™ mouthwashes. There is controversy in the literature regarding the influence of mouthwash products, with or without alcohol, on observed surface roughness in different filling materials.[17182223] Thus, it can be assumed that the effects of the solution will depend not only on its composition but also on the material that gets in contact with it. Comparing M1 and M2, Biodentine presented higher roughness at all immersion solutions. This is probably because of the composition of Biodentine™ having an influence due to its higher solubility when compared to the GIC.[713] Kaup et al.[6] state that Biodentine™ contains calcium hydroxide and calcium oxide. Both compounds release OH− and Ca2+ ions, which result in increased solubility.[21]

After analyzing the time × material interaction, it was observed that Biodentine™ presented statistically similar mean values at all times and also showed higher microhardness than Fuji IX GIC at 48 h, 7 days, and 14 days. At 21 days, Biodentine and GIC presented similar microhardness. M1 behavior regarding immersion time, shows its lower susceptibility. Oppositely, the higher microhardness of Biodentine™, when compared to the Fuji IX GIC, is probably related to the presence of a plasticizing water-soluble polymer within the liquid and to the lower water/powder ratio,[24] resulting in better mechanical properties. However, the behavior similarity trend at 21 days is an interesting record.

Regarding material × solution interaction, it was observed that Biodentine™ presented higher microhardness means in distilled water and in Listerine® Cool Mint than that the Fuji IX GIC. GIC behavior may be due to its water sensibility. However, with Colgate Plax Ice Infinity, no differences were observed for these materials regarding microhardness. No related work is known to the researchers on Biodentine™ and its interaction with the mouthwash products at this moment.

Restorative materials in the oral cavity are frequently exposed to complex and diverse conditions[15] which can affect their properties. The relevance of the results with respect to roughness and microhardness is to show the need of new ways to polish or a way to protect the Biodentine surface in such a way as to prevent biofilm accumulation. In addition, to establish a mean of surface protection can be beneficial to reduce the direct effect of mouthwashes, food or beverages, and saliva establishing some means of surface protection would also be beneficial in decreasing the direct action of mouthwashes, food solutions, and saliva. It also allows to observe that the permanence of this material inside cavity for over 14 days will promote a higher roughness surface. This will help draw clear boundaries in which its indication has maximum longevity regarding its temporary indication.

CONCLUSION

Biodentine™ showed higher roughness at 21 days, while the Fuji IX GIC showed no variation at 48 h, 7 days, 14 days, and 21 days.

Biodentine™ showed higher roughness than the Fuji IX GIC at 7, 14, and 21 days and when submitted to immersion solutions;

The Fuji IX GIC presented lower microhardness than Biodentine™ at 48 h, 7 days, and 14 days, while at 21 days, they were equivalent.

Biodentine™ presented higher microhardness than the Fuji IX GIC when immersed in distilled water and in the alcohol-based mouthwash. Whereas in the nonalcohol-based solution, the microhardness values were similar.

Financial support and sponsorship

This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001.

Conflicts of interest

There are no conflicts of interest.