Journal of Conservative Dentistry

ORIGINAL ARTICLE
Year
: 2012  |  Volume : 15  |  Issue : 3  |  Page : 265--269

The effect of various surface contaminants on the microleakage of two different generation bonding agents: A stereomicroscopic study


Pragya Kumar1, Arvind Shenoy2, Sonal Joshi3,  
1 Department of Conservative Dentistry and Endodontics, ITS-CDSR, Muradnagar, Ghaziabad, Uttar Pradesh, India
2 Department of Conservative Dentistry and Endodontics, Bapuji Dental College, Davangere, India
3 Department of Conservative Dentistry and Endodontics, K.L.E's Institute of Dental sciences, Belgaum, Karnataka, India

Correspondence Address:
Pragya Kumar
Department of Conservative Dentistry and Endodontics, ITS-CDSR, Muradnagar, Ghaziabad, Uttar Pradesh - 201 206
India

Abstract

Aim: The aim of this in vitro study was to evaluate the microleakage of two different generation bonding agents in the presence of various surface contaminants. Materials and Methods: Class V cavities were prepared on 150 extracted human permanent molars. The samples were randomly divided into two main groups of 75 teeth each. Group I: Fifth generation bonding system (Single Bond, 3M). Group II: Seventh generation bonding system (iBond, Kulzer). Subgroups were formed according to exposure to different surface contaminants (saliva, blood, caries disclosing agent and haemostatic agent). Cavities were restored with hybrid composite (Z-100, 3M) and evaluated for microleakage. The scores were subjected to SQtSQ test and analysis of variance (ANOVA) test. Results: Single Bond and iBond did not provide complete resistance to microleakage when there was no contamination. Microleakage was minimum in the no contamination subgroup and maximum with the haemostatic agent subgroup for both the groups. Conclusion: Single bond showed lesser micro leakage in contaminated conditions.



How to cite this article:
Kumar P, Shenoy A, Joshi S. The effect of various surface contaminants on the microleakage of two different generation bonding agents: A stereomicroscopic study.J Conserv Dent 2012;15:265-269


How to cite this URL:
Kumar P, Shenoy A, Joshi S. The effect of various surface contaminants on the microleakage of two different generation bonding agents: A stereomicroscopic study. J Conserv Dent [serial online] 2012 [cited 2019 Oct 22 ];15:265-269
Available from: http://www.jcd.org.in/text.asp?2012/15/3/265/97955


Full Text

 Introduction



The past decade has seen tremendous advancements in bonding techniques, technologies and applications in dental practice. Many modern dental materials claim that they possess high bond strength with excellent adaptation to the tooth structure, and a less tedious procedure with fewer clinical steps; however, the fact remains that bonding is a highly technique sensitive procedure. According to Baren - "The way by which a composite resin adapts to the tooth substance depends more on the nature of the tooth surface than on the properties of the composite resin". [1] In order to have successful adhesion between resin and tooth structure, it is necessary that the adhesive substrate should not be contaminated. Contamination at any step of the bonding process can adversely impact the longevity of the restoration and hamper its clinical success. [2] Contamination can lead to microleakage, which in turn leads to sensitivity, pulpal irritation, tooth discoloration, secondary caries and eventual loss of restoration and clinical failure.

This study evaluated the performance of a fifth generation bonding agent (Single Bond) and a seventh generation bonding agent (iBond), with respect to various surface contaminants. No study till date has compared the microleakage of the two different generation bonding agents in the presence of different contaminants such as saliva, blood, caries disclosing agents and haemostatic agents.

 Materials and Methods



Sample selection

A total of one hundred and fifty intact maxillary or mandibular extracted human permanent molar teeth were selected for the study. The teeth were stored in a solution of 0.1% (wt. /vol) thymol to prevent dehydration and bacterial growth.

Sample preparation

Class V cavities were made on the buccal surfaces of each tooth using a high speed hand piece with air/water spray and # 245 carbide bur. Each cavity was 2 mm wide, 1.5 mm deep and 6 mm long, paralleling the cemento-enamel junction (CEJ). The gingival half of the preparation was extended 0.5 mm below the CEJ. Cavosurface was finished to a butt joint with a # 55 slow speed diamond point. The enamel margins were beveled using a flame shaped carbide bur and the gingival margins were left at a 90° angle or butt joint.

Division of samples into groups

The samples were randomly divided into two main groups of 75 teeth each:



Group I: Cavities were treated with a fifth generation bonding system (Single Bond, 3M ESPE-3M General Offices St. Paul, MN 55144 USA).Group II: Cavities were treated with a seventh generation bonding system (iBond, Heraeus Kulzer D- 63450, HANAU, GERMANY).

The main groups were further divided into five subgroups according to exposure to different surface contaminants.

Subgroup A (Control)



Subgroup IA: Application of Single Bond according to the manufacturer's instructions.Subgroup IIA: Application of ibond according to the manufacturer's instructions.

Subgroup B (Saliva contamination)

Whole fresh unstimulated human saliva was collected from volunteers who had not eaten food or consumed any liquid for 30 minutes prior to the collection. The saliva was collected in a sterilized glass beaker for immediate use.



Subgroup IB: After etching, fresh whole unstimulated human saliva was pooled over the bonding area with a microbrush and left undisturbed for 10 seconds. Rinsing was done for 10 seconds with air/ water spray. Excess was blot dried with tissue paper pellets. Priming and bonding was carried out, followed by curing.Subgroup IIB: After priming and bonding, fresh whole unstimulated human saliva was pooled over the bonding area with a microbrush and left undisturbed for 10 seconds. Rinsing was done for 10 seconds with air/water spray. Excess was blot dried with tissue paper pellets. Repriming and bonding was carried out, which was followed by curing.

Subgroup C (Blood Contamination)

At the time of the experiment, fresh whole blood was obtained from volunteers by pricking the spirit wiped forefinger with a lancet.





Subgroup IC and IIC: Similar procedure as in the subgroup IB and IIB was done with blood as a surface contaminant.

Subgroup D (Caries disclosing dye contamination)



Subgroup ID and IID: Caries disclosing agent (Caries Detector, Dental Source, 13343, Sherman Way N Hollywood CA 91605 USA) was used as the surface contaminant in a similar manner as with saliva and blood.

Subgroup E (Haemostatic agent)



Subgroup IE and IIE: Haemostatic agent (Viscostat, Ultradent ProductsINC, 505 West10200South Jordan UTAH 84095 USA) was used as the surface contaminant in a similar manner as with saliva, blood and caries disclosing agent.

Preparation of samples for dye penetration

All the cavities were then restored with hybrid composite Z-100 (3M ESPE-3M General Offices St. Paul, MN 55144 USA) with each increment cured for 40 seconds with visible light curing unit (3M). After the restoration, the samples were stored for 24 hours in distilled water. The samples were then thermocycled for 1000 cycles between 5°C ± 2°C and 55°C ± 2° with dwell time of 30 seconds. Apical openings of the teeth were occluded with resin composite and then the entire tooth surface was painted with two coats of air resistant varnish (nail polish) to within 1 mm of the restoration margins. The teeth were immersed in 0.5% basic fuschin dye for 24 hours. Each tooth was sectioned in the bucco-lingual direction through the center of the bulk of Class V restorations, and evaluated with reflected light binocular stereomicroscope at 10 × magnification.

Stereomicroscopic readings

Following scoring criteria was followed for dye penetration at composite tooth interface:



0 = No dye penetration1 = Dye penetration upto, but not beyond ½ to occlusal or gingival wall.2 = Dye penetration upto, but not contacting the axial wall.3= Dye penetration along the axial wall

The graduations in the microscope were converted into millimeter as follows:

[INLINE:1]



The data was then subjected to statistical analysis, and the difference in microleakage of the two bonding systems with different surface contamination conditions was compared.

 Results



[Table 1] shows linear dye penetration (microleakage) of Fifth generation bonding agent (Single Bond) at enamel and gingival margins with various surface contaminants. 't' test was applied to Group I (Single Bond) and control subgroup was compared with surface contamination subgroups. When comparing IA with IB, microleakage was not significant at both the margins (Enamel, P -0.0886 and Gingival, P-0.0658).When comparing subgroups IA with IC, microleakage was not significant at enamel margin (P -0.1123) and significant at gingival margin (P -0.0122). When comparing subgroups IA with ID, microleakage was not significant at enamel margin (P -0.0.1296) and significant at the gingival margin (P -0.0115). Microleakage between subgroups IA and IE was significant at enamel margin (P -0.0193), and highly significant at gingival margin (P -0.0003).{Table 1}

[Table 2] shows linear dye penetration (microleakage) of Seventh generation bonding agent (iBond) at enamel and gingival margins with various surface contaminants. 't' test was applied to Group II (iBond), and control subgroup was compared with surface contamination subgroups. When comparing IIA with IIB, microleakage was very significant at both the margins (Enamel, P-0.0026 and Gingival, P-0.0081). Between subgroups IIA and IIC, microleakage was highly significant at both the margins (Enamel, P-0.0003 and Gingival, P-0.0005). Microleakage between subgroups IIA and IID was very significant at enamel margin (P -0.0061), and highly significant at gingival margin (P-0.0008). Microleakage between subgroups IIA and IIE was highly significant at both margins (Enamel, P-1.4E-05 and Gingival, P-0.0001).{Table 2}

Intra group comparison (among contaminated subgroups) showed that microleakage was not significant (P->0.05) at enamel margin when 't' test was applied between subgroups IB, IC, ID and IE. At gingival margin, microleakage was not significant (P->0.05) between subgroups IB-IC, IB-ID, IC-ID and IC-IE but significant (P-<0.05) between subgroups IB-IE and ID-IE. Intra group comparison (among contaminated subgroups) of the second group ('t' test) showed a significant (P-<0.05) microleakage between subgroups IIB and IIE at both the enamel and gingival margins. For the remaining subgroups, microleakage was not significant (P->0.05) at either of the two margins.

Inter group comparisons of the subgroups ('t' test) showed no significant (P->0.05) microleakage at both margins between subgroup IA and IIA. Microleakage between subgroups IB-IIB (P-4.9E-05), IC-IIC (P-7.5E-06), ID-IID (P-4.4E-06) and IE-IIE (P-3.7E-07) was highly significant at enamel margin. Microleakage between subgroup IB-IIB, IC-IIC, ID- IID and IE- IIE was not significant (P->0.05) at the gingival margin.

The analysis of variance (ANOVA) of Group I at enamel margin showed no significant variations in marginal sealing ability between the subgroups with 'F' value of 1.4800 and 'P' value of 0.2175. The ANOVA of Group I at gingival margin showed very significant variations in marginal sealing ability between the subgroups with 'F' value of 4.3263 and 'P' value of 0.003481.The ANOVA of Group II at enamel margin showed highly significant variations in marginal sealing ability between the subgroups with 'F' value of 7.9538 and 'P' value of 2.41E-05. The ANOVA of g0 roup II at gingival margin showed highly significant variations in marginal sealing ability between the subgroups with 'F' value of 6.4180 and 'P' value of 0.000185.

 Discussion



The basic concept of adhesion is "The closer the contact between the adhesive and the adherent, the stronger is their junction". [3] Micromechanical interlocking and chemical interaction between functional monomer and tooth substrate are the prerequisites for achieving good bonding. Efficient adhesion between cavity walls and restorative materials is desired for producing well sealed and long lasting restorations. [4] Good wetting of dentin surface maintains the plasticity and permeability of demineralized collagen fibrillar network which is critical for optimal hybridization. [5]

The major disadvantage of adhesive procedures is that they accompany higher placement complexities and are technique sensitive. Various causes of microleakage under composite restoration are polymerization shrinkage, the difference between coefficient of thermal expansion of resin and tooth structure, lack of self-sealing mechanism and occlusal loading. [6] Contamination at any time of bonding procedure can also lead to microleakage.

A study with scanning electron microscopy has concluded that the etching of surfaces contaminated with oral fluids regardless of length of exposure, produces a dramatic alteration of surface topography. [7] In the current study we found that where no contamination was done, minimum microleakage was obtained. When the two control subgroups were compared, microleakage was not significant at both the margins. These results are in contrast to another study in which iBond showed significant microleakage at coronal margin compared to Single Bond. The authors concluded that the technique protocols associated with iBond are labor intensive and include multiple applications, and have increased waiting periods prior to light polymerization. The reason for this was that iBond is a acetone based bonding agent. On the other hand, Single Bond is alcohol based which increases the diffusion of bonding agent in the dentine, and thus enhances the adhesion. [8]

Single Bond showed less microleakage at enamel margin compared to the gingival margin. The probable reason may be the cavosurface bevel at the enamel margin which increases the surface area of a bondable margin. Enamel surface bevel exposes the enamel rod end on. [9] The increased microleakage at the gingival margin in cavities below the CEJ may be because of polymerization shrinkage of the composites towards the tightly bonded enamel cavosurface margin. [10] iBond showed more microleakage at the enamel margin than the gingival margin. The probable reason may be the chemical composition of iBond. iBond is acetone based with a pH of 2.4 which produces a shallow depth etch, and less abundant resin tag complex. [11]

Saliva contamination did not have significant effect on Single Bond; however, a very significant effect was seen on iBond at both the margins. This might be due to more technique sensitivity of iBond, and a difference in the chemical composition of two bonding agents. In the presence of salivary contamination, iBond showed a significantly greater microleakage at the enamel margin as compared to Single bond. On the other hand, no significant difference was found between the two at the gingival margin. It has been shown that acid conditioned enamel surface readily absorbs salivary constituent, reducing the surface energy and rendering the surface less favorable for bonding. [2] At the enamel margin, the dried film of salivary protein inhibits penetration of the bonding agent into the hydroxyapatite. At the gingival margin, microleakage was due to the protein absorbing properties of dentin. [12]

In this study, cavities were rinsed for 10 seconds with air/ water spray after the exposure to surface contaminants. In contrast, various studies have concluded that re-etching after contamination is required to establish the shear bond strength comparable to the control group. [13],[14] When the cavities were exposed to blood, Single Bond showed no significant microleakage at enamel margin; however, a significant microleakage was seen at the gingival margin when compared to control. iBond showed highly significant microleakage at both the margins when compared to control. The probable reason might be difference in chemical composition of the two bonding agents. When comparing Single Bond with ibond, ibond showed a highly significant microleakage at the enamel margins, and not significant at the gingival margins. The probable reason could be some interaction between exposed collagen meshwork and blood protein components that could inhibit primer infiltration into dentin.

An important aim of minimal invasive dentistry is to prevent sound and healthy tooth structure removal. Various caries disclosing dyes that stain only the bacterial infected dentin have been widely used as guide to remove the infected layer of dental caries. If not washed off properly, the residual caries disclosing dye can affect adhesive bonding. In this study when the cavities were exposed to caries disclosing agent (Caries detector), Single Bond showed significant microleakage at the gingival margin, but not at the enamel margin. iBond showed very significant microleakage at the enamel margin and highly significant microleakage at the gingival margin when compared to control. A probable cause is the differences in the depth of etch between the two groups. iBond with a pH of 2.4 does not etch as efficiently as phosphoric acid. The result is in agreement with an in vitro study which concluded that caries disclosing solution increases the microleakage of adhesive systems. [15] When comparing Single Bond with iBond, highly significant microleakage at enamel margin was seen. Microleakage with caries disclosing agent contamination may be due to the entrapment of remaining dye particles in the dentin that can adversely affect the wetting of dentin by bonding agents.

In Class V cavities with gingival margins below CEJ, thorough isolation might not be always possible. Blood and gingival crevicular fluid due to inflammation of adjacent gingiva contaminate the prepared surfaces. The most common procedure used to control bleeding and decrease the flow of gingival fluid involves the use of topical hemostatic agent. [16] Also, retraction cord impregnated with haemostatic agent can facilitate gingival tissue retraction. [17] In the present study, when cavities were exposed to a haemostatic agent (Viscostat), Single Bond showed highly significant microleakage at gingival margin but no significant microlekage at enamel margin when compared to the control. iBond showed a highly significant microleakage at both the margins when compared to the control. When comparing Single bond with iBond, highly significant microleakage was seen at enamel margin.

The increased microleakage might be because Viscostat is a viscous gel composed of ferric sulphate. The viscous nature makes it harder to remove it from the dentin surface, and could potentially coagulate proteins present in the dentinal fluid. The coagulated proteins and residues of ferric sulfate could in turn inhibit the infiltration of the bonding agent into the etched enamel surfaces and dentinal tubules. In a study, Viscostat reduced bond strength most significantly when dried on the dentin surface. However with water rinsing and using cleansing agent (Concepsis), bond strength approached the control values. [18] In another study, authors found that for cleansing the haemostatic agent contaminated surfaces by phosphoric acid, etching decreased the bond strength of self adhesive resin cement upto 18% to 21%. They recommended aluminium oxide particle abrasion for cleansing of surface contaminated by haemostatic agents. [16]

Microleakage was not significant at enamel margin between all the surface contaminated subgroups of Single Bond. This might be due to the cavosurface bevel at the enamel margin which exposes the rod ends. At the gingival margin for Single Bond, microleakage was significant when saliva and caries disclosing agent subgroup was compared with haemostatic agent subgroup. This might be due to the high viscosity of the haemostatic agent. Microleakage was not significant for all the subgroups of iBond at both the margins, except between saliva and haemostatic agent subgroup. This might be due to the composition of iBond and the viscous nature of the haemostatic agent.

 Conclusion





When no contamination was done, Single bond showed slightly more microleakage at gingival margin and iBond at the enamel margin. iBond does offer ease of use, but is most technique sensitive. The Single Bond on the other hand is safe and effective though has more procedural steps.Single Bond was superior to the iBond in bonding contaminated surfaces. In presence of various surface contaminants, Single Bond provided better marginal seal at enamel margin. iBond showed microleakage at both the margins. Saliva contamination produced the minimum microleakage and haemostatic agent produced the maximum microleakage for both the bonding agents.Clinically, to achieve a successful bonding in Class V cavities, contamination should be avoided by thorough isolation and tissue retraction, prior to bonding. Adequate surface cleansing protocol should be taken into consideration if the contamination occurs before proceeding for the bonding procedure.

By testing the marginal sealing ability of bonding agents by dye penetration method alone, one cannot conclude superiority of one bonding agent over another. Further studies are needed with different microleakage tests to check the effective marginal seal. The effect of saliva, blood, caries disclosing agent and haemostatic agent on marginal sealing ability, dimensional stability and adhesive strength should be further tested.

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