|Year : 2016 | Volume
| Issue : 2 | Page : 59-63
Effect of blood contamination on the push-out bond strength of two endodontic biomaterials
Alireza Adl1, Fereshte Sobhnamayan1, Nooshin Sadatshojaee1, Niloofar Azadeh2
1 Department of Endodontics, Faculty of dentistry, Shiraz University of Medical Sciences, Shiraz, Iran
2 Student, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran
|Date of Web Publication||21-Apr-2016|
Dr. Fereshte Sobhnamayan
Department of Endodontics, Dental School of Medicine, Ghasrodasht Street, Ghomabad Avenue, Shiraz
Source of Support: None, Conflict of Interest: None
Objectives: The aim of the present study was to compare the effect of blood contamination on the push-out bond strength of mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) at different time intervals. Materials and Methods: One hundred and twenty dentin slices from single-rooted human teeth were sectioned and instrumented to achieve a diameter of 1.3 mm. The specimens were allocated into eight groups based on the materials used, the presence or absence of blood contamination, and the time. MTA and CEM were mixed and introduced into the lumens of dentin slices in groups 1–4 and 5–8, respectively. In blood-contaminated groups (1, 3, 5, and 7), the specimens were in direct contact with blood. The push-out test was performed in groups 1, 2, 5, and 6 after 3 days and in othergroups after 21 days. For the evaluation of failure modes, the samples were examined under a light microscope at × 40 magnifications. Data were analyzed by three-way analysis of variance (ANOVA). Results: The bond strength of MTA was higher than that of CEM, regardless of contamination and time (P < 0.05). For both materials, regardless of contamination, there was an increase in the bond strength from days 3to 21 (P < 0.05). Regardless of materials and time, blood contamination had no significant effect on the bond strength of materials (P > 0.05). Inspection of the samples revealed that the bond failure was predominantly of the mixed type in all groups. Conclusion: Blood contamination had no adverse effect on the bond strengths of both MTA and CEM; resistance of MTA to displacement was greater than that of CEM cement. However, the elapsed time, from 3 to 21 days, resulted in an increase in bond strength of both materials.
Keywords: Blood contamination, calcium-enriched mixture, mineral trioxide aggregate, push-out bond strength
|How to cite this article:|
Adl A, Sobhnamayan F, Sadatshojaee N, Azadeh N. Effect of blood contamination on the push-out bond strength of two endodontic biomaterials. J Res Dent 2016;4:59-63
|How to cite this URL:|
Adl A, Sobhnamayan F, Sadatshojaee N, Azadeh N. Effect of blood contamination on the push-out bond strength of two endodontic biomaterials. J Res Dent [serial online] 2016 [cited 2018 Jun 18];4:59-63. Available from: http://www.jresdent.org/text.asp?2016/4/2/59/180997
| Introduction|| |
Immediate repair of root perforation is recommended to avoid increased inflammation with time and to achieve optimum outcome., An ideal root repair material should be well-tolerated by periradicular tissues, easy to manipulate, insoluble, dimensionally stable, radiopaque, and have good adaptation and adherence to the dentinal walls. Among various materials that have been used for the repair of perforation, mineral trioxide aggregate (MTA) possesses many of these properties and additionally has the ability to promote cementum and bone formation over its surface., As these properties are necessary for many other endodontic procedures, MTA has been successfully used in direct pulp capping, pulpotomy,  apexification of immature teeth, periapical surgeries, nonsurgical repair of root resorption, and for the repair of horizontal root fractures. In spite of its outstanding physical and biological characteristics, this cement has some disadvantages, including questionable antimicrobial properties, long setting time, difficulty of handling, and high cost. Moreover, acidic environments  have adverse effects on MTA. Recently, a calcium-silicate-based cement, (CEM), has been introduced as a root-end filling material. It comprises different calcium compounds such as oxide, sulfate, phosphate, carbonate, silicate, hydroxide, and chloride compounds. It can set in wet environments and has suitable film thickness and flow and shorter setting time compared with MTA. It has been shown that CEM has accepted coronal and retro-sealing ability , and antibacterial efficacy comparable with those of calcium hydroxide. One distinctive characteristic of CEM is its ability to induce a layer of hydroxy lapatite on its surface and form a chemical bond with dentin. In clinical applications, CEM has been used for repair of root perforations, pulp capping, apical plug formation, and treatment of root resorption.
Considering the clinical applications of MTA and CEM, in many cases blood comes into contact with or is even incorporated into these materials. This contamination may have deleterious effects on the bond strength of these materials to dentin, which is an important factor in achieving a proper seal between the root canal and the external surface of the root. Currently, there is insufficient knowledge about the effect of blood contamination on the bond strength of CEM to dentin. Therefore, this ex vivo study was designed to evaluate and compare the effect of blood contamination on the bond strengths of CEM and MTA up to 21 days in a push-out bond strength model.
| Materials and Methods|| |
Freshly extracted human teeth, including mandibular single-rooted premolars and maxillary anterior incisors, with intact or only small caries lesions were selected and stored in 0.5% Chloramine-T at 4°C for up to 1month before use. Midroot dentin was horizontally sectioned by means of a diamond saw microtome (SP1600 microtome; Leica, Nußloch, Germany), yielding 120 dentin slices with a thickness of 1.2 ± 0.05 mm. Lumens of the root dentin disks were enlarged with Gates–Glidden burs (DentsplyMaillefer, Ballaigues, Switzerland), sizes 2–5, to achieve a standardized diameter of 1.3 mm. Specimens were then allocated randomly into eight groups of 15 on the basis of the materials used (MTA or CEM), the presence or absence of blood contamination, and the time of the push-out test (3 or 21 days) [Table 1].
|Table 1: Study groups and the mean±standard deviation of push-out in experimental groups|
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MTA (Angelus, Londrina, PR, Brazil) and CEM (Bionique Dent, Tehran, Iran) were mixed with distilled water according to the manufacturers' instructions and introduced with slight pressure into the lumens of the slices. In the blood-contaminated groups, the specimens were placed in a plastic container on a piece of gauze, which was soaked in blood and a piece of gauze wet with normal saline was placed on their upper part. In this way, MTA or CEM came into direct contact with blood during setting. The blood used in this study was taken from one of the researchers.
In the non-contaminated groups, a piece of gauze soaked in normal saline, instead of blood, was placed in the bottom of the plastic container. The other procedures were similar to those for blood-contaminated groups. The plastic containers were sealed and kept in an incubator at 37°C and 100% relative humidity until the push-out test was carried out (3 or 21 days).
After the experimental periods, the push-out bond strength of each specimen was measured by means of a universal testing machine (Zwick/Roell, Z050;Zwick/Roell, Ulm, Germany). The dentin slices were placed on a metal slab with a central hole to allow for the free motion of the plunger. A downward force was applied to the surfaces of the CEM and MTA cements by means of a 0.7mm-diameter cylindrical stainless steel plunger at a speed of 1 mm/min [Figure 1]. The maximum load applied to the cements before dislodgement occurred was recorded in Newtons. For bond strengthto be expressed in megapascals (MPa), the recorded value in Newtons was divided by the adhesion surface area of MTA in mm2, calculated according to the following formula: 2πr × h, where π is the constant 3.14, r is the root canal radius, and h is the thickness of the root slice in millimeters.
|Figure 1: A cylindrical stainless steel plunger of universal testing machine loading on CEM inside a root slice and the universal testing machine|
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Evaluation of failure patterns
The slices were then examined under a light microscope (Dino-lite, Taiwan) at × 20 magnification to determine the nature of the bond failure. Each sample was categorized into one of three failure modes [Figure 2]: Adhesive failure at the dentin–cement interface, cohesive failure within the cement, and mixed failure.
|Figure 2: Adhesive failure note the clean canal wall; cohesive failure; and mixed failure|
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The data were analyzed by three-way analysis of variance (ANOVA) with the Statistical Package for Social Sciences, version 16 (SPSS Inc, Chicago, IL, USA).
| Results|| |
The mean push-out bond strengths and standard deviations of the four experimental groups are shown in [Table 1]. The highest (3.75 ± 2.52 MPa) and the lowest (1.15 ± 0.77 MPa) bond strength values were recorded in the MTA/blood contamination group at 21 days and the CEM/blood contamination group at 3 days, respectively. Regardless of contamination and time, MTA had significantly higher bond strength than CEM (P = 0.001). For both materials, regardless of contamination, there was an increase in the bond strength from days 3to 21 (P = 0.002). Regardless of material and time interval, blood contamination had no significant effect on the bond strengths of materials (P = 0.900). Inspection of the samples revealed that failure mode was predominantly of the mixed type in the groups.
| Discussion|| |
The present study was designed to evaluate the bond strengths of MTA and CEM to the dentinal canal at two time intervals, with or without blood contamination. Resistance of dental materials to dislodgement forces is an important factor in the success of different endodontic procedures such as repair of perforations, apical barrier formation, and root-end filling. Evaluation of the bond strength between these materials and dentin will show the value of adhesion between them. Different techniques can be used to evaluate the bond strength of a dental material to dentin, including tensile, shear, and push-out bond strength tests. In the present study, the push-out bond strength test was used, as it is the most reliable method for evaluating the resistance of materials to dislodgement forces, based on the results of previous studies.,
In the presence of tissue fluids or in wet conditions, the hydration of MTA and CEM powder results in the development of hydroxyapatite crystals and the formation of a hybrid layer between dentin and these materials., This hybrid layer fills the microscopic gap between MTA and the dentinal wall and, with time, the mechanical bond leads to chemical bonding. Studies have shown that, similarly to MTA, CEM can form a chemical bond with dentin; however, in contrast to MTA, CEM shows this ability endogenously and even in the presence of normal saline.,
When it comes to blood, although it can provide moisture for hydration of MTA and CEM, the cells and proteins of blood can, at the same time, adversely affect the physical properties of these cements. In an in vitro study, Jasiczak and Zielinski  demonstrated that mixing powdered red blood cells with Portland cement reduced the compressive strength and increased the setting time of the cement. Remadnia et al. also showed that hemoglobin or whole blood increased the porosity of Portland cement.
According to the results of the present study, MTA had significantly higher bond strength than CEM, regardless of contamination and time. This result is not in agreement with those of Rahimi et al. who reported no significant differences in the bond strength of CEM and MTA. One reason for the observed discrepancies may be different experimental setups, particularlythe different humid environments in which the samples were cured. Meanwhile, in different studies, different types of materials with different chemical formulations are used and should not be expected to behave identically. In the current study, MTA Angelus was used, comprising 80% Portland cement and 20% bismuth oxide; however, ProRoot MTA comprises 75% Portland cement, 20% bismuth oxide, and 5% calcium sulfate dehydrate.
The results of the current study revealed an increase in the bond strength of two cements from days 3 to 21, consistent with the results of Rahimi et al., who reported an increase in the bond strength of these two materials from 24 h to 7 days. Studies that have evaluated the effect of time on the bond strength of CEM are limited. In the present study, bond strength of CEM to dentin increased significantly from 3 to 21 days; however, further studies with longer time intervals are recommended to determine the time in which CEM reaches its maximum bond strength. Regarding MTA, Gancedo-Caravia et al. similarly evaluated the effect of curing time on the push-out strength of MTA. While they did not find any significant increase in dry conditions, under wet conditions the push-out strength of MTA showed a statistically significant increase when curing time was increased from 3 to 21 days.
In the present study for both biomaterials, contamination with blood did not influence the resistance to dislodgement, which is not in agreement with the results of studies carried out by Vanderweele et al., and Rahimi et al., in which the blood contamination had negative effects on the retention of MTA and CEM as perforation repair materials. It is noteworthy that the experimental model used for blood contamination in the present study was different from that used by Vanderweele et al., and Rahimi et al. There is a lack of evidence to suggest that the use of any particular experimental setup is superior to another. In the abovementioned studies, blood was not removed from the walls of the perforated area, to simulate the worst clinical situation of hemorrhage., However, in most clinical situations, different steps are taken to control the bleeding before biomaterials are applied. Therefore, in the present study, the inner walls of the disks were not contaminated with blood, but the specimens were allowed to set in direct contact with blood. Blood includes different cells and proteins and blood remaining on dentinal walls may occlude the dentinal tubules and prevent the formation of a chemical bond between the materials and the walls.
Different types of failure patterns have been reported for MTA in different studies. In the present study, although some samples exhibited cohesive and adhesive failure patterns, the bond failure was predominantly of the mixed type. This result is in accordance with that of another study on the retention characteristics of these two cements, where the failure patterns were of the mixed type in all samples. Within the limitations of this in vivo study, MTA showed higher bond strength than CEM. Bond strengths of both materials increased from 3 to 21 days.
| Conclusions|| |
Resistance of White Mineral trioxide aggregate to displacement was greater than CEM., and elapse of time from 24 h to 7 days and contamination resulted in an increase and no change in bond strength of these two materials to dentin, respectively.
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[Figure 1], [Figure 2]