|Year : 2017 | Volume
| Issue : 9 | Page : 1201-1205
Effect of saliva decontamination procedures on shear bond strength of a one-step adhesive system
E Ülker1, S Bilgin2, F Kahvecioğlu1, A İ Erkan1
1 Department of Restorative Dentistry, Faculty of Dentistry, Selcuk University, Konya, Turkey
2 Department of Pedodontics, Faculty of Dentistry, Selcuk University, Konya, Turkey
|Date of Acceptance||28-Jan-2016|
|Date of Web Publication||26-Oct-2017|
A İ Erkan
Department of Restorative Dentistry, Faculty of Dentistry, Selcuk University, Selcuklu 42075, Konya
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Aim: To evaluate the effect of different saliva decontamination procedures on the shear bond strength of a one-step universal adhesive system (Single Bond™ Universal Adhesive, 3M ESPE, St. Paul, MN, USA). Materials and Methods: The occlusal surfaces of 75 human third molars were ground to expose dentin. The teeth were divided into the following groups: Group 1 (control group): Single Bond™ Universal Adhesive was applied to the prepared tooth according to the manufacturer's recommendations and light cured; no contamination procedure was performed. Group 2: Bonding, light curing, saliva contamination, and dry. Group 3: Bonding, light curing, saliva contamination, rinse, and dry. Group 4: After the procedure performed in Group 2, reapplication of bonding. Group 5: After the procedure performed in Group 3, reapplication of bonding. Then, composite resins were applied with cylindrical-shaped plastic matrixes and light cured. For shear bond testing, a notch-shaped force transducer apparatus was applied to each specimen at the interface between the tooth and composite until failure occurred. The data were statistically analyzed using one-way ANOVA. Results: One-way ANOVA revealed significant differences in shear bond strength between the control group and experimental Groups 2 and 4 (P < 0.05). No significant difference was found for experimental Groups 3 and 5 when compared to the control group (P > 0.05). Conclusion: The present in vitro study showed that water rinsing is necessary if cured adhesive resin is contaminated with saliva to ensure adequate bond strength.
Keywords: Decontamination, one-step adhesive system, shear bond strength
|How to cite this article:|
Ülker E, Bilgin S, Kahvecioğlu F, Erkan A &. Effect of saliva decontamination procedures on shear bond strength of a one-step adhesive system. Niger J Clin Pract 2017;20:1201-5
|How to cite this URL:|
Ülker E, Bilgin S, Kahvecioğlu F, Erkan A &. Effect of saliva decontamination procedures on shear bond strength of a one-step adhesive system. Niger J Clin Pract [serial online] 2017 [cited 2020 May 25];20:1201-5. Available from: http://www.njcponline.com/text.asp?2017/20/9/1201/187325
| Introduction|| |
Adhesive systems are widely used in daily clinical practice because of increased demand for esthetic restorations. However, dental adhesives and composites are extremely undefended against contamination., As providing good moisture control is a common problem in adhesive dentistry, the bonding procedure requires both adequate isolation and control of contamination.,
Rubber dam isolation is usually the standard method as it facilitates visualization and makes it possible for the dentist to control contamination. On the other hand, it can be difficult to place a rubber dam on a severely fractured tooth, in patients who are having problems opening their mouths, on newly erupted molars, or on the tooth of a child who is respiring orally. In addition, the rubber dam clamp might be irritating for some patients. For these reasons, it is not feasible to use a rubber dam in all clinical cases. Instead, cotton rolls are used during bonding procedures, but some kind of contamination might still occur.,,
Minimal intervention procedures have gained importance in the last decade because of the development of restorative materials. Among these, the most developed materials are composite materials and adhesive systems. However, they are still sensitive to fluid contamination with saliva, blood, or gingival crevicular fluids. Perdigão et al. suggested that salivary glycoproteins adsorb into the polymerized adhesive structure and form a barrier that prevents adequate copolymerization of composite resin increment. This affects the quality of the bond, leading to microleakage between the resin composite and tooth structure. This may result in loss of the restoration, recurrent caries, and postoperative sensitivity and discoloration.
Adhesion to dentin has been the subject of debate because it is a heterogeneous substrate, with much higher organic and water content than enamel. Nowadays, developed adhesive systems such as “self-etch adhesives” have been introduced to be tolerant of salivary contamination. Self-etch systems eliminate the rinsing and drying steps, which simplifies the bonding procedure. In addition, technical sensitivity (i.e., over-wetting or -drying) is reduced, and better adhesion is achieved. Single bond universal adhesive (Single Bond™ Universal Adhesive, 3M ESPE, USA) is a seventh generation self-etching adhesive system. The manufacturer claims that the adhesive system tolerates slight/moderate saliva contamination before adhesive application (Single Bond Universal Adhesive Technical Product Profile).
In several clinical situations, contamination could occur after adhesive application. To prevent negative effects on dental bonding, practitioners commonly need to decide between two clinical alternatives: Performing all the adhesive steps again or using decontamination procedures (an easier and quicker alternative).
The aim of the present study was to evaluate the effect of different saliva decontamination procedures on the shear bond strength of a single-bottle universal adhesive system to dentin when the contamination occurred after light curing. The null hypothesis was that the bond strength values for all tested decontamination procedures would not differ.
| Materials and Methods|| |
Seventy-five extracted caries-free human third molars were mounted after thorough preparation in self-cure acrylic resin; the occlusal surface of each tooth was ground on wet diamond disks to remove enamel and to expose a 5–6-mm area of mid-depth dentin (n = 75). The surface was ground flat with 600-grit Al2O3 papers. The prepared teeth were stored in distilled water until preparation of the specimens for bonding. Before bonding, fresh whole saliva was collected from a single female donor in a sterile beaker and was used immediately.
The teeth were randomly divided into five groups of 15 teeth each (n = 15). Schematic representation of the bonding procedures is shown in [Schema 1].
Group 1 (control): The specimens were not subjected to saliva contamination. The single-bottle universal adhesive system (Single Bond™ Universal Adhesive) was applied to the dentin of each specimen according to the manufacturer's instructions. Single Bond™ Universal Adhesive was applied to the prepared tooth and rubbed in for 20 s. The adhesive was gently air dried for approximately 5 s to evaporate the solvent, and then light-cured (BlueLex Gt 1200, Monitex, Taiwan) for 10 s.
Group 2: The single-bottle universal adhesive system was applied as in the control group, and dentin surfaces were subjected to contamination with saliva for 15 s using a micro-brush. The surfaces were dried for 5 s using an air-water syringe from a 10-cm distance.
Group 3: The same procedure was used as in Group 2, but after contamination, the surfaces were rinsed for 10 s with a water stream from an air/water syringe, followed by air drying for 5 s from a 10-cm distance.
Group 4: After the procedure used in Group 2, the adhesive resin was reapplied and light cured.
Group 5: After the procedure used in Group 3, the adhesive resin was reapplied and light cured.
A Teflon tube 2 mm in diameter and 3 mm high was applied on the surfaces, filled with composite resin (Z550, 3M ESPE, USA), and light cured (BlueLex Gt 1200, Monitex, Taiwan) for 20 s.
Before the shear bonding test, samples were stored in 37°C distilled water for 1 day. The shear bond strength was measured using an Instron universal testing machine (TSTM 02500, Elista, Turkey) at a cross-head speed of 1 mm/min. The force was measured in newtons divided by the cross-sectional area and is reported as megapascals.
A notch-shaped shearing rod was used to debond the resin cylinders. The mean shear bond strength of each group was analyzed using one-way ANOVA with SPSS 21 Software for Windows (IBM, Chicago, USA). Post hoc comparisons were performed using Tukey's honestly significant difference test. Statistical significance was set in advance at P = 0.05.
Scanning electron microscopic analysis
For scanning electron microscopic (SEM) analysis, five extracted caries-free human third molars were subjected to the procedures described above. To remove the smear layer, each tooth was submerged in a 17% ethylenedinitrilotetraacetic acid solution (pH = 7.8) for 5 min, rinsed with distilled water, immersed in a 5.25% NaOCl solution for 5 min, and then stored in distilled water until use. Untreated samples were used as controls. Samples were sputtered with gold under vacuum in a sputtering device (Hummer VII Caoter; Anatech Corp., USA). The surfaces were analyzed by (SEM; JSM 5410, Japan).
| Results|| |
Shear bond strength comparisons
The mean shear bond strength and standard deviation values for the surface treatment procedures for each group are shown in [Table 1].
|Table 1: The shear bond strength values (means and standard deviations) of different surface treatments|
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One-way ANOVA revealed significant differences in shear bond strength between the control group (Group 1) and the experimental groups (P< 0.05). Groups 2 and 4 showed statistically lower bond strength values when compared with Groups 1, 3, and 5. There was no significant difference among Groups 1, 3, and 5 [Graph 1].
Scanning electron microscopic surface analysis
Images showing the most significant results obtained for each group are shown in [Figure 1] and [Figure 2]a,[Figure 2]b,[Figure 2]c,[Figure 2]d. In the SEM observation, the control group showed uniform formation of resin tags and a normal hybrid layer [Figure 1].
|Figure 1: Group 1 (Control group): Uniform formation of resin tags and a normal hybrid layer|
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|Figure 2: (a) Group 2: Cracks were showed between the bonding and composite surface. (b) Group 3: Similar images were obtained with the control group. (c) Group 4: Cracks were showed between rebonding and bonding surface. (d) Group 5: Showed a thicker adhesive surface than control group and experimental Groups 2 and 3|
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The experimental Group 2 specimens showed cracks or blisters, indicating that saliva or air might have been trapped between the bonding and composite surface [Figure 2]a. The experimental Group 3 specimens yielded images similar to those for the control group [Figure 2]b. Experimental Group 4 showed cracks between rebonding and the bonding surface [Figure 2]c. Experimental Group 5 showed a thicker adhesive surface compared with the control group and experimental Groups 2 and 3 [Figure 2]d.
| Discussion|| |
In the present study, the null hypothesis was rejected because the groups that were only air dried as a decontamination procedure showed significantly lower values than the control group.
Saliva contains a variety of electrolytes, including sodium, potassium, calcium, magnesium, bicarbonate, and phosphates. Also found in saliva are immunoglobulins, proteins, enzymes, mucins, and nitrogenous products such as urea and ammonia. Salivary contamination of the operating field is a major clinical problem in restorative dental procedures, especially when rubber dam isolation is difficult or cannot be used, such as deep cervical lesions, or when an indirect esthetic restoration is seated. In the present study, natural saliva was chosen as the contaminant because artificial saliva may distort the results. Besides, many studies have accepted whole healthy human saliva as an available contaminating medium.,, The effect of saliva on bond strength is thought to be related to water in saliva and salivary glycoproteins.,,
The effect of salivary contamination is an important issue and has caused great controversy. With different study designs and materials, various results in dentin have been observed. Some studies have reported that salivary contamination of dentin caused lower bond strength values.,,, However, others have shown no statistically significant differences between contamination and no contamination.,, In addition, Yazici et al. found no difference between groups in a microleakage test.
For self-etch systems (sixth and seventh generation), the required acidity is ensured by the addition of acidic monomers. When applied to the tooth structure, the acidic adhesive will demineralize and penetrate into the surface simultaneously. However, when these materials are used on intact enamel, a separate enamel etching process is needed. Self-etch adhesives with pH <2 are classified as “strong” self-etch adhesives whereas those with pH >2 are classified as “mild.” Mild self-etch adhesives are preferred over strong ones because they still provide a strong bond to dentin. The pH of Single Bond Universal Adhesive is 2.7, and the product is considered a mild self-etch adhesive. According to the manufacturer, Single Bond Universal Adhesive is tolerant to slight/moderate saliva contamination before adhesive application (Single Bond Universal Adhesive Technical Product Profile). However, in our study, saliva contamination procedures were implemented at the end of the adhesive application process.
In the present study, bond strength decreased in the two groups (Group 2 and 4) that were decontaminated without water rinsing. In previous studies, various adhesive systems have been used and similar results have been observed. Kim et al., Ari et al., and Darabi et al. found no difference between controls and saliva-contaminated and rinsed groups. Quite similar to our study, Sattabanasuk et al. demonstrated similar bond strengths in control and reapplied bonding groups, and they also found statistically significant differences between a control group and a group with saliva contamination and only air drying. Drying without rinsing might leave behind some salivary glycoproteins and other organic substances that prevent interaction of composite resin with the oxygen inhibition layer. It seems that reapplication of adhesive was not enough to avoid this. In addition, in SEM analysis, only the dried and reapplied group showed cracks into the adhesive interface.
During dental restorative treatments, saliva contamination could happen before, during, or after the adhesive application. Studies in the literature can shed light on the subject. Yoo et al. and Sattabanasuk et al. evaluated the effect of saliva contamination before light curing using two-step self-etching adhesives and demonstrated significantly lower values in a group with saliva contamination and only air drying. However, when saliva-contaminated teeth were washed and then air dried, no significant differences between the treated group and a control group were evident. In another study, Cobanoglu et al. evaluated different decontamination procedures in various steps. They found significantly lower bond strengths in a saliva-contaminated prepared dentin group and in contaminated primer and adhesive resin groups.
All-in-one adhesive systems are relatively new materials. Therefore, limited information can be found in the literature about the effect of saliva contamination and essential decontamination procedures to ensure adequate bond strength. Further studies should be performed to better understand this topic.
| Conclusion|| |
According to the results of thisin vitro study, water rinsing is a necessary step when cured adhesive resin is contaminated with saliva. Even if adhesive reapplication is performed, water rinsing is mandatory. In SEM surface analysis, groups that received only air drying or air drying plus reapplication demonstrated internal cracks into the adhesive interface. In groups where the adhesive resin was reapplied, a thicker adhesive interface was seen.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]