The effect of hemostatic agents and dentin cleansing protocols on shear bond strength of resin composite using universal adhesive: an in vitro study

Abstract

Background

During restoring class II and V cavities with resin composite, hemostatic agents are frequently used to control gingival bleeding and/or gingival fluid to provide a dry field which is crucial for efficient bonding. Hemostatic agents may adversely affect the bonding procedure, thus their removal prior to bonding is essential. The current study evaluates the effect of two hemostatic agents and different dentin cleansing protocols on the shear bond strength of resin composite to dentin using a universal adhesive.

Methods

Ninety premolars were sectioned to expose coronal dentinal surfaces which were divided into 3 groups: control group, not treated with hemostatic agent (n = 10); a group treated with Viscostat “20% ferric sulphate” (n = 40); and a group treated with Viscostat clear “25% aluminum chloride” (n = 40). The groups treated with hemostatic agents were subdivided into 4 subgroups according to the cleansing protocol: water, phosphoric acid, katana cleaner, and air abrasion. Shear bond strength (SBS) of resin composite bonded to the treated dentin using a universal adhesive was measured after thermocycling.

Results

Two-way ANOVA showed that hemostatic agent, cleansing protocol and their interaction has significant effect on SBS (p < 0.0001). Viscostat (10 ± 3.3 MPa) exhibited lower SBS than Viscostat Clear (16.2 ± 5.5 MPa). Acid etching (17.3 ± 7.3 MPa) showed higher SBS compared to Katana Cleaner (12.6 ± 4.7 MPa), water (12.1 ± 4.8 MPa) and air abrasion (10.8 ± 2 MPa).

Conclusion

The use of hemostatic agents can adversely affect the bond strength of universal adhesives to dentin. Phosphoric acid provided the best hemostatic agent-cleansing protocol while katana cleaner and air abrasion demonstrated inferior results.

Background

The demand for tooth-colored restoration is always rising because of today’s image-conscious society. The use of both direct and indirect aesthetic restorations such as composite and ceramics with imperceptible margins, as well as the desire for good aesthetic outcomes, is on the rise in modern dental practice [1]. Based on minimal invasive dentistry approach, composite restorations are widely used to repair a broken or carious tooth. Acid-etch technique has been introduced earlier to allow bonding resin composite to tooth structure through micro-mechanical retention. Recent research has established that good bonding between the tooth substrate and restorations is the result of a combination of micromechanical retention and chemical bonding by functionalized monomers with hydroxyapatite [2]. The optimum bonding between the restoration and tooth margins is crucial for longevity of clinical use [3]. Inadequate bonding may lead to recurrent caries, micro-gap formation and subsequent failure of restoration. The clinical approach for achieving successful and long-lasting bonding between the tooth substrate and dental adhesives is extremely technique dependent [4]. For successful bonding, meticulous tooth surface preparation, conditioning, and environmental control are required.

Resin composite restorations are extremely sensitive to moisture contamination. Hemorrhage and gingival crevicular fluid seepage during bonded restoration application must be tightly managed, or the bond strength of resin composite restorations to tooth structure would be compromised [5]. Rubber dam isolation is usually applied since it allows for greater clarity of vision and keeps moisture under control throughout the restorative treatment. Nonetheless, optimal isolation of the area to avoid contamination with saliva, gingival crevicular fluid, and blood is challenging [6]. Following acid-etching step, demineralization caused by etching exposes the collagen network, making it more prone to react with blood protein compounds, impairing primer and adhesive penetration and compromising the bond to the dental substrate [7]. Furthermore, contamination could occur after the adhesive application in various clinical circumstances. To minimize detrimental effects on dental bonding, practitioners must frequently choose between two clinical options: repeat all adhesive steps or utilize decontamination techniques, which is a simpler and faster option [8]. There is minimal data on the efficacy of various decontamination treatments in cases of blood contamination to avoid negative effects on bonded restorations.

Chemical solutions used as hemostatic agents, which typically contain aluminum chloride (Viscostat clear, VC), ferric sulphate (Viscostat, V) or epinephrine, could reduce bleeding and gingival flow, allowing practitioners to work in a reasonably dry field. Aluminum chloride reduces capillary fragility by triggering the precipitation of mucosal proteins during blood channel contraction. Ferric sulphate, on the other hand, is a concentrated form of astringent that causes superficial and local clotting [9].

Astringents (coagulative agents) and vasoconstrictors (adrenergic agents) are the two types of hemostatic agents. The hemostatic agents are acidic, with pH values ranging from 0.7 to 3. As a result, they can remove the smear layer and cause minor demineralization. Their long-term use can even eradicate peritubular dentin [10]. Hemostatic agents, commonly referred to as astringents, have been in clinical use in dentistry for many years for management of hemorrhage and gingival crevicular fluid flow. These chemicals cause tissue shrinkage and/or hemostasis, allowing the dental practitioner to achieve a clean and dry field for the bonding technique [11, 12].

Some researchers have looked at the influence of hemostatic drugs on bond strength, with inconsistent results [13–15]. They have mostly had a detrimental impact on bond strength values. On the other hand, some researches have demonstrated that some cleaning agents had a favorable effect on shear bond strength [16]. Contaminants are thought to block the flow of resin monomer into the dentinal tubules and impair the establishment of the hybrid layer [17].

Different dentin cleaning methods following tooth preparation have been proposed to remove the remnant debris. These methods could be chemical or mechanical [18]. Commercially available cavity cleaners (such as Katana cleaner), rinsing with water, and utilizing air abrasion have been suggested to restore bond strength to dentin contaminated with hemostatic chemicals. A low-pressure aluminum oxide particle abrasion has recently been shown to be an efficient mechanical cleansing surface treatment for eliminating remaining provisional luting chemicals [19]. Particle abrasion produces rough and uneven surfaces, which improves the bonding of restorations to enamel and dentin. However, there are limited evidence regarding this method. Katana Cleaner (Kuraray Noritake, Japan) has recently been introduced as a dentin cleaner. It has surface-active characteristic of 10-Methacryloyloxydecyl dihydrogen phosphate (10-MDP) salt which improves its efficiency in dentin cleaning [20].

The current study evaluated the effect of two types of hemostatic agents and different dentin cleansing protocols on the bond strength of resin composite to dentin using a universal adhesive. The tested null hypothesis was that the shear bond strength of resin composite to dentin is not affected by the two hemostatic agents or the different cleansing methods used.

Materials and methods

Sample size calculation

Sample size was determined using the G*Power 3.1.9.7 statistical software. In this study, an effect size (f) of 0.5 was chosen, with a significance level (α) of 0.05 and a power of 0.8. There was a total of nine test groups. Based on these parameters, the calculated total sample size was 63 specimens, which is seven specimens per group. However, to account for any potential errors in specimen preparation or unexpected failures, the decision was made to use 10 specimens per group. Therefore, the sample size was increased to 90 specimens.

Specimen preparation for shear bond strength test

Ninety non-carious human premolars, extracted for orthodontic reasons, were used in this study according to protocol (# 124-10-22) approved by Research Ethics Committee, King Abdulaziz University, Saudi Arabia. The teeth were examined to be free of cracks, caries or marked physiological or pathological resorption. Any calculus deposits or soft debris were removed using an ultrasonic scaler. All teeth were stored in chloramine T solution for 24 h for disinfection and then kept in distilled water at 37º C until use within 2 months following extraction.

Occlusal enamel was removed perpendicular to the long axis of each tooth using a low-speed diamond saw (Allied Techcut, Rancho Dominguez, CA USA) under water spray. The sectioned teeth were embedded in self-cured acrylic resin to allow proper handling during bond strength testing. Silicon carbide papers (320 followed by 600 grit) were used for 60 s to expose flat mid coronal dentin, enamel-free, surfaces with standardized smear layers.

The specimens were then rinsed with water thoroughly and randomly divided into nine groups (n = 10) according to the type of hemostatic agent and the method of cleaning used. Group 1 (control): Dentinal surfaces were not contaminated with any hemostatic agent nor any cleaning method was used. Groups 2, 3, 4 & 5: Viscostat solution (20% ferric sulphate, Ultradent, USA) was applied to all dentinal surfaces for two minutes using a microbrush (Pearson Dental Supply, CA, USA) then different cleaning methods were used as follows: Group 2: contaminated dentin was rinsed with water for 30 s and air-dried to remove excess moisture, Group 3: dentin was rinsed and dried then 35% phosphoric acid (3 M ESPE Scotchbond™, Neuss, Germany) was applied for 15 s, rinsed for 30 s, then was blot dried using a cotton pellet to remove excess water, leaving the surface glistening without pooling of water, Group 4, after rinsing and drying contaminated dentin, katana cleaner solution (Kuraray Noritake Dental Inc., Okayama, Japan) was applied and rubbed using a micro-brush for at least 10 s, then rinsed and dried, Group 5: contaminated dentinal surfaces were air-abraded for 10 s using 27µ aluminum oxide particles under 40 Psi pressure from a 2 mm distance, then rinsed with water and blot-dried using cotton pellets. Groups 6, 7, 8 & 9: Viscostat clear solution (25% aluminum chloride, Ultradent, USA) was applied to all dentinal surfaces for two minutes using a microbrush, then rinsed with water for 30 s and air-dried to remove excess moisture. Then, contaminated dentin was either cleaned with water, phosphoric acid, katana cleaner or air abrasion as mentioned previously. The composition and manufacturer of all materials used in this study are presented in Table 1, while the experimental design is presented in Fig. 1.

Table 1.

Materials used in this study, their composition and manufacturer

Material	Composition	Manufacturer
Viscostat	20% ferric sulphate, polyethylene glycol, propylene glycol	Ultradent, USA
Viscostat Clear	25% aluminum chloride, polyethylene glycol, sodium borate, dimethicone	Ultradent, USA
Katana cleaner	MDP (10-Methacryloyloxydecyl dihydrogen phosphate), triethanolamine, polyethylene glycol, accelerator, dyes, water. (pH = 4.5)	Kuraray Noritake Dental Inc., Okayama, Japan
Scotchbond Universal Etching Gel	35% phosphoric acid, water, silica, polyethylene glycol, aluminium oxide	3 M ESPE, St Paul, MN, USA
Single Bond Universal	Methacryloyloxydecyl dihydrogen phosphate (MDP) phosphate monomer, dimethacrylate resins, HEMA, Vitrebond Copolymer, filler, ethanol, water, initiators, silane	3 M ESPE, Deutshland GmbH, Neuss, Germany
Filtek Z350 XT Resin Composite	Bisphenol A Diglycidyl Ether Dimethacrylate, Diurethane Dimethacrylate, silane treated silica and zirconia, Polyethylene Glycol dimethacrylate, Triethylene glycol dimethacrylate	3 M ESPE, St Paul, MN, USA

Fig. 1.

Flow chart presenting the experimental design of the current study

Bonding procedure

A split Teflon mold with an internal diameter 3 mm and height 2 mm was used for adhesive application and resin composite build-up. According to manufacturer’s instructions, Single Bond universal adhesive (3 M ESPE, Deutshland GmbH, Neuss, Germany) was applied to dried dentin for 20 s, gently air-dried for 5 s and light-cured for 10 s (Light Emitting Diode curing unit, 3 M ESPE Elipar, Germany, 1200mW/cm², 430–480 nm). Then, nanohybrid resin composite (Filtek Z 350 XT, 3 M ESPE, St Paul, MN, USA) was packed into the split Teflon mold followed by light curing for 40 s. After, removal of the Teflon mold, any excess adhesive or composite flashes were removed cautiously using a sharp scalpel, then all specimens were stored in distilled water at 37 °C for 24 h. To simulate 6 months of aging in the oral environment, the teeth were subjected to 5000 thermal cycles (Thermocycler THE-1100, Mechatronik, Pleidelsheim, Germany) between 5°-55 °C with a dwell time of 30 s and a transfer time of 30 s [21].

The shear bond strength was tested using a universal testing machine (IN-STRON, Norwood, MA, USA). A shear force was applied to the resin-dentin interface of each specimen at a cross-head speed of 1 mm/minute. After debonding, maximum loads at bond failure were recorded in Newtons (N), and bond strengths were calculated in megapascals (MPa). All debonded samples were examined under a stereomicroscope (Meiji Techno Co., Ltd., Tokyo, Japan) at 40x magnification to evaluate the mode of failure which was classified into adhesive (A) or mixed (M) failures.

Statistical analysis

Data collection and statistical analysis was performed using JMP 17 Statistical Discovery from SAS software (SAS Campus Drive. Cary, NC, USA). The Kolmogorov-Smirnov test was used to assess the normal distribution of the results. It was determined that shear bond strength data within the tested groups followed a normal distribution. Consequently, parametric testing were employed. One-way analysis of variance (ANOVA) was used to for sorting and evaluating difference in SBS data between all groups including control group, followed by Post-hoc Tukey test. Furthermore, to investigate the effects of the two main factors individually (hemostatic and cleaning agents) and their interaction on the shear bond strength (SBS) of resin composite to dentin, Two-way ANOVA was employed on test groups (not including control group). For hemostatic agent independent variable, there were two levels (Viscostate and Viscostate clear) and for cleaning agent, there were four levels (Acid Etch, Katana Cleaner, Water and Air Abrasion). Estimated marginal means of SBS for the independent variable “hemostatic agent” were calculated and compared using Student t-test. Moreover, estimated marginal means of SBS for independent variable “cleaning agent” were calculated and compared using One-way ANOVA test. Results were considered significant at P value < 0.05.

Results

One-way ANOVA showed a significant difference between all groups. (p < 0.0001). Post-hoc Tukey test was performed to delineate areas of significance at p = 0.05. Two-way ANOVA revealed a significant difference between groups (p < 0.0001). Hemostatic agent, cleaning agent and the interaction factor has significant effect on shear bond Strength (p < 0.0001). Results are presented in Table 2; Fig. 2.

Table 2.

Descriptive and statistical analysis of shear bond strengths (MPa) of resin composite to dentin

Hemostatic agent, cleaning agent)	Mean (MPa) ± SD	95% confidence interval		One-way ANOVA p-value	Two-way ANOVA p-value
		Lower 95%	Upper 95%		Overall model	Independent variable “hemostatic agent”	Independent variable “Cleaning agent”	Interaction variable “hemostatic agent* cleaning agent”
Viscostat Clear, Acid Etch	23.26 ± 3.52 A	20.74	25.78	< 0.0001*	< 0.0001*	< 0.0001*	< 0.0001*	< 0.0001*
Control	20.61 ± 4.16 AB	17.63	23.59
Viscostat Clear, Water	16.13 ± 2.42 BC	14.40	17.86
Viscostat Clear, Katana Cleaner	14.68 ± 4.37 CD	11.55	17.80
Viscostat, Air Abrasion	10.84 ± 2.15 DE	9.30	12.37
Viscostat, Acid Etch	10.80 ± 3.69 DE	7.97	13.63
Viscostat Clear, Air Abrasion	10.73 ± 1.66 DE	9.54	11.92
Viscostat, Katana Cleaner	10.51 ± 4.28 DE	7.45	13.58
Viscostat, Water	8.00 ± 2.46 E	6.24	9.77

Means not connected by the same letter are significantly different (p < 0.05)

Fig. 2.

A bar graph representing the mean values and standard deviations of the shear bond strength for the test groups, using each of the two hemostatic agents with different cleansing protocols

The estimated marginal means for SBS for the independent variable “hemostatic agent” are presented in Table 3; Fig. 3. Student t-test shows significant difference in estimated SBS (p < 0.0001) where Viscostat (10 ± 3.3 MPa) had significantly lower SBS than Viscostat Clear (16.2 ± 5.5 MPa). This indicates that regardless of the cleaning agent used, Viscostat had a more detrimental effect on the shear bond strength of resin composite to dentin compared to Viscostat clear.

Table 3.

Estimated marginal means for the independent variable (hemostatic agent)

Level (hemostatic agent)	Number	Mean (MPa) ± SD	95% confidence interval		T-test p- value
			Lower 95%	Upper 95%
Viscostat	39	10 ± 3.3 B	8.9	11.1	< 0.0001
Viscostat Clear	40	16.2 ± 5.5 A	14.4	17.9

Levels not connected by the same letter are significantly different (p < 0.05). One specimen from Viscostat group, cleaned with acid-etch, failed prematurely during thermocycling (before testing), it was excluded from statistical analysis

Fig. 3.

A bar graph representing the mean values and standard deviations of shear bond strength for each hemostatic agent

The estimated marginal means for SBS for the independent variable “cleaning agent” are presented in Table 4; Fig. 4. The one-way ANOVA analysis of the estimated SBS revealed a significant difference between the various cleaning agents (p = 0.0007). Acid-etching (17.3 ± 7.3 MPa) had significantly higher SBS compared to Katana Cleaner (12.6 ± 4.7 MPa), water (12.1 ± 4.8 MPa) and air abrasion (10.8 ± 2 MPa). This indicates that regardless of the hemostatic agent used, acid etching was found to be more effective in restoring the shear bond strength of resin composite to dentin compared to other cleaning agents.

Table 4.

One-way ANOVA analysis of the independent variable (cleaning agent)

Level (cleaning agents)	Number	Mean (MPa) ± SD	95% confidence interval		p-value
			Lower 95%	Upper 95%
Acid Etch	19	17.3 ± 7.3 A	13.8	20.8	0.0007
Katana Cleaner	20	12.6 ± 4.7 B	9.9	11.6
Water	20	12.1 ± 4.8 B	10.4	14.8
Air Abrasion	20	10.8 ± 2 B	9.8	14.3

Levels not connected by the same letter are significantly different (p < 0.05). One specimen from Viscostat group, cleaned with acid-etch, failed prematurely during thermocycling (before testing), it was excluded from statistical analysis

Fig. 4.

A bar graph representing the mean values and standard deviations of shear bond strength for the different cleaning protocols

The frequency of failure mode is presented in Table 5; Fig. 5. For failure mode analysis within each group, the Chi-square test found a significant difference in the mode of failure (p < 0.000), with predominantly adhesive failures. When failure modes were compared between different groups, the distribution of failure modes was statistically similar (p = 0.28). Representative images of adhesive and mixed failures are shown in Fig. 6.

Table 5.

Statistical analysis of failure mode distribution among different groups

Group (hemostatic agent, cleaning agent)	Failure count	Adhesive	Mixed	Chi-square test within each group P-value	Chi-square test between groups P-value
	Failure percent
Viscostat Clear, Acid Etch	Count	6	4	< 0.000	0.28
	%	60	40
Control	Count	7	3	< 0.000
	%	70	30
Viscostat Clear, Water	Count	9	1	< 0.000
	%	90	10
Viscostat Clear, Katana Cleaner	Count	8	2	< 0.000
	%	80	20
Viscostat, Air Abrasion	Count	8	2	< 0.000
	%	80	20
Viscostat, Acid Etch	Count	9	0	< 0.000
	%	100	0
Viscostat Clear, Air Abrasion	Count	8	2	< 0.000
	%	80	20
Viscostat, Katana Cleaner	Count	9	1	< 0.000
	%	90	10
Viscostat, Water	Count	10	0	< 0.000
	%	100	0

One specimen from Viscostat group, cleaned with acid-etch, failed prematurely during thermocycling (before testing), it was excluded from statistical analysis

Fig. 5.

Mosaic plot demonstrating failure mode distribution among different groups

Fig. 6.

Representative images of failure mode evaluated by stereomicroscope at 40x magnification: (a) adhesive failure, (b) mixed failure

Discussion

Ensuring a dry and clean field is essential in the adhesive bonding of dental restorations. Dentists often face challenges when contaminants such as blood, remnants of temporary cement materials, or saliva are present during the application of adhesive materials. To address some of these challenges, the use of hemostatic agents to control bleeding during adhesive bonding is a common practice. However, it is important to note that if these hemostatic agents are not properly cleaned from the dentin surface, they well jeopardize the bond strength to dentin [10, 22, 23]. Therefore, it is crucial to thoroughly clean the hemostatic materials before bonding to dentin to maintain a proper and durable bond between the restoration and dentin. This study aimed to assess the impact of various cleaning methods on the SBS of dental composite to dentin after contamination of dentin with two different hemostatic agents, in comparison to a control group with non-contaminated dentin.

Shear bond strength test is considered reliable and provides a relative screening of bonding effectiveness at various areas and depths within the dentin. By measuring shear bond strength, it becomes possible to assess the quality of the bond and compare it across different regions or depths of the dentin. However, non-uniform stress distribution at the interface may occur during shear testing, resulting in bond strength values lower than the actual ones which may present a limitation of this test [24].

The present study explored the influence of various cleaning methods on SBS when used in conjunction with different hemostatic agents. The findings highlighted that different cleaning methods have varying effects on SBS, particularly when employed with different hemostatic agents. These findings indicate a rejection of the null hypothesis, as both the contamination agents and the cleaning methods led to a significant difference in SBS among the groups (p-value < 0.05).

Cleaning methods used in the present work are either water, 35% phosphoric acid, katana cleaner (mainly, MDP, triethanolamine, polyethylene glycol) or air-abrasion using 27µ aluminum oxide particles. The findings of the study suggest that the cleaning methods employed with Aluminum Chloride were more effective in restoring the initial SBS compared to Ferric Sulfate.

Regardless of the cleaning methods used, it was observed that Viscostat hemostatic agent had a more detrimental effect on SBS compared to Viscostat Clear. This difference in performance can be attributed to the distinct chemical compositions of the two hemostatic agents and their respective mechanisms of action. Viscostat, containing 20% Ferric Sulfate, controls bleeding by forming superficial and deep clots [10]. On the other hand, Viscostat Clear, which contains 25% Aluminum Chloride, reduces capillary fragility and triggers the precipitation of mucosal proteins during blood channel contraction [10, 25]. The differing mechanisms of action in addition to the different nature of materials considering the higher viscosity of ferric sulfate which is often supplied in gel form, may explain the varying influence of these materials on dentin shear bond strength after cleaning.

The influence of both aluminum chloride and ferric sulfate as hemostatic agents on SBS was investigated previously, and the results showed a significant decline in SBS with the use of both agents [10]. In addition, it was observed that ferric sulfate caused a greater deterioration in bond strength, which aligns with the findings of the present study.

On the other hand, regardless of the hemostatic agents, the use of 35% phosphoric acid significantly restored the SBS when compared to other cleaning methods with a non-significant difference between the other cleaning methods. The higher bond strength obtained with phosphoric acid could be attributed to the dual effect of etching dentin surface which results in removal of smear layer and the cleaning of the hemostatic agent from tooth surface. Only with Aluminum Chloride, phosphoric acid restored the SBS to be comparable to or slightly higher than the control group, while this was not achieved when phosphoric acid was used with Ferric Sulfate solution. Etching dentin surface with phosphoric acid removes the smear layer and dissolve the appatite crystals exposing the collagen fibrils and creating a room for the adhesive to flow around the collagen fibrils [26]. The dental adhesive employed in this study was Single Bond Universal, containing MDP phosphate monomer and hydroxyethyl methacrylate (HEMA), and it was applied in a self-etch mode. The topic of acid etching before the application of self-etch adhesives remains a subject of debate in the literature. Some studies indicate that bond strength can be improved when etch and rinse mode is used with self-etch adhesives [27], while others have shown a decline in bond integrity and durability when etch and rinse technique is applied to self-etch adhesives [28]. In addition, some researchers found no difference between the two methods regarding bond integrity [29]. It has been well documented that the acidity encountered during the bonding process increases the host-derived endogenous enzymatic activity in dentin matrices influencing bond durability and lead to degradation of hybrid layers created by these adhesives [30, 31]. Therefore, future long-term studies are needed to investigate the durability of the adhesive bond after dentin contamination with hemostatic agent and cleaning with phosphoric acid.

Single Bond Universal is characterized by the presence of 10-Methacryloyloxydecyl dihydrogen phosphate (MDP), which is a monomer that bonds chemically to the hydroxyapatite of the tooth structure and thus was reported to resist hydrolysis and enhance resin-dentin bond strength [2, 27–29]. It can be clear that MDP was added mainly to enhance bond strength when the adhesive is applied using self-etch mode. If acid etching is performed, it completely demineralizes the dentinal surface, leaving no minerals to interact with MDP.

Various outcomes were observed when examining the cleaning effectiveness of Aluminum Chloride and Ferric Sulfate. In the case of Aluminum Chloride, it was found that phosphoric acid exhibited the highest efficacy in restoring SBS, followed by water and Katana cleaner with air abrasion being the least effective in cleaning the dentin surface. However, when it came to Ferric Sulfate, none of the cleaning methods were able to restore the SBS, and the results were significantly lower than the control group. These findings highlight the differing effectiveness of cleaning agents on bond strength restoration, depending on the specific hemostatic agent used. Ferric sulfate is usually provided in a gel form to control the flow of the material on the tooth surface which may explain the difficulty in removing the solution effectively from dentin surface.

The MDP-containing Katana Cleaner was investigated in the present study due to its performance in previous studies as it improved bond strength when used to clean contaminated Zirconia [32, 33]. Karana Cleaner has a high cleaning effect due to the surface active characteristic of MDP Salt. The hydrophobic group of MDP adheres to contamination, while MDP salt reduces the surface tension of contamination and facilitates its removal (Kuraray Noritake Dental Inc., Technical Product Brochure, Okayama, Japan 2020). However, limited studies evaluated the influence of using Katana cleaner with contaminated dentin. The use of Katana cleaner in the present work did not restore the bond strength in both cases of hemostatic agents and the results of using katana cleaner were almost similar to water cleaning. This may be attributed to the pH of katana cleaner “4.5” which is much higher than that of the acid etchant (pH = 0.1) resulting in inability to completely remove all remnants of hemostatic agents. However, it showed much better results with aluminum chloride than ferric sulfate hemostatic agent which may be attributed to the lower viscosity of aluminum chloride which facilitated its partial removal. Further future studies are required to evaluate the efficacy of katana cleaner in improving bond strength to hemostatic-contaminated dentin.

These findings are consistent with previous studies that have demonstrated improved performance in cleaning dentin surface contamination when using phosphoric acid and chlorhexidine, compared to the use of Katana Cleaner [25]. The agreement between our results and prior research further supports the effectiveness of phosphoric acid as reliable cleaning agents for achieving optimal bond performance.

Air abrasion with Viscostat clear (Aluminum chloride) provided the lowest SBS values, and with Viscostat (Ferric sulfate) was similar to other cleaning methods that resulted in low SBS compared to the control. Therefore, air abrasion was not able to properly clean the dentinal surfaces from the hemostatic agents which may be attributed to the parameters of the procedure as the size of aluminum oxide particles, the pressure used or the time of application. However, these results are in contrast to previous studies that demonstrated that air abrasion had enhanced resin-dentin bond strengths [23, 34].

The failure pattern usually reflects the strength of the bond at the interface, the stronger the bond the higher will be the probability of cohesive failure while adhesive failure usually occur with weaker bonds. In the current study, there was no pure cohesive failure, however, adhesive and mixed failures occurred. Within each group, the adhesive failure predominated, while there was no significant difference between groups regarding the mode of failure. However, it can be noticed that the highest number of mixed failures occurred in the viscostat clear group cleaned with acid-etch and the control group where both groups exhibited highest bond strength values.

There are several limitations of this in-vitro study including inability to fully simulate the oral environment such as presence of saliva, dentinal fluid under positive pulpal pressure, temperature and pH changes, dynamic forces as well as variable cavity designs which were not provided by the specimens used in the study. Furthermore, absence of dentin elemental analysis following different cleansing protocols and resin-dentin interface examination are considered limitations of this study.

Conclusion

Viscostat hemostatic agent adversely affected the shear bond strength of the universal adhesive to dentin while viscostat clear did not. Phosphoric acid provided the best hemostatic agent-cleansing protocol while katana cleaner and air abrasion demonstrated inferior results. Further long-term studies are needed to validate the best modality for optimum bonding to hemostatic agent-contaminated dentin.

Abbreviations

MDP

Methacryloyloxydecyl dihydrogen phosphate

N

Newtons

MPa

Megapascals

ANOVA

Analysis of variance

SBS

Shear bond strength

HEMA

Hydroxyethyl methacrylate

Author contributions

M.A-N., M.S.H., R.A., T.S.A.: Conceptualization, Data curation, Formal analysis, Methodology, Investigation. R.A., Y.A., A.A., N.K.: Methodology, Project administration, Resources, Writing-original draft. R.A.A., G.H.N., S.J.A., D.A.A.: Funding acquisition, Resources, Writing-review and editing, Supervision.

Funding

No financial support was obtained for this research.

Data availability

All data are present in the manuscript, and raw data can be requested from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

Ethical approval of protocol (# 124-10-22) was obtained by the Research Ethics Committee, King Abdulaziz University, Saudi Arabia. The written informed consent was obtained from all patients from whom the teeth were extracted according to the protocol (# 124-10-22) approved by Research Ethics Committee, King Abdulaziz University, Saudi Arabia.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.