|Year : 2014 | Volume
| Issue : 1 | Page : 46-50
Evaluation of the sealing ability of pulp capping agents against leakage on direct pulp capping with a computerized fluid filtration meter
Muhammet Yalçin1, Çagatay Barutcigil2, Reyhan Sisman1, Tevfik Yavuz3, Hasan Oruçoglu4
1 Department of Restorative Dentistry, Faculty of Dentistry, Inönü University, Malatya, Turkey
2 Department of Restorative Dentistry, Faculty of Dentistry, Akdeniz University, Antalya, Turkey
3 Department of Prosthodontics, Faculty of Dentistry, Selçuk University, Konya, Turkey
4 Department of Endodontics, Faculty of Dentistry, Abant Izzet Baysal University, Bolu, Turkey
|Date of Web Publication||20-Mar-2014|
Department of Restorative Dentistry, Faculty of Dentistry, Akdeniz University, 07058 Antalya
Source of Support: None, Conflict of Interest: None
Objective: The aim of this study was to assess the sealing abilities of two calcium hydroxide (Ca[OH] 2) pastes and two mineral trioxide aggregates (MTA) against leakage on direct pulp capping with a computerized fluid filtration (CFF) method. Materials and Methods: The 60 recently extracted sound human molar teeth were sectioned at the level of the highest pulp horn to obtain dentin discs of 0.5 ± 0.2 mm. The dentin discs were numbered and permeability measurements were done before and after the operation for the same sample. For simulating direct pulp capping, dentin discs were perforated with a standard diamond bur and restorated with four different capping materials: Dycal, Calcimol light-curing (LC), ProRoot MTA and DiaRoot BioAggregate. Fluid movement measurements were tested with a CFF method and a mean value was calculated for each specimen. Results: Calcimol LC and Dycal showed significantly higher fluid conductance values compared to other pulp capping materials (P < 0.05). There were no significant differences between ProRoot MTA and DiaRoot BioAggregate (P > 0.05). Conclusion: Within the limitations of this study, it can be concluded that using the MTA materials as a pulp-capping agent would be more efficient than Ca (OH) 2 materials with regard to pulpal microleakage.
Keywords: Calcium hydroxide, computerized fluid filtration, direct pulp capping, microleakage, mineral trioxide aggregate
|How to cite this article:|
Yalçin M, Barutcigil Ç, Sisman R, Yavuz T, Oruçoglu H. Evaluation of the sealing ability of pulp capping agents against leakage on direct pulp capping with a computerized fluid filtration meter. J Res Dent 2014;2:46-50
|How to cite this URL:|
Yalçin M, Barutcigil Ç, Sisman R, Yavuz T, Oruçoglu H. Evaluation of the sealing ability of pulp capping agents against leakage on direct pulp capping with a computerized fluid filtration meter. J Res Dent [serial online] 2014 [cited 2020 Sep 24];2:46-50. Available from: http://www.jresdent.org/text.asp?2014/2/1/46/129025
| Introduction|| |
The consequences of pulp exposure from caries, trauma or unexpected tooth preparation procedures can be severe and may include pain and infection. Direct pulp capping is an effective treatment for preserving pulp vitality. There are various approaches regarding capping materials and treatment of exposed pulp.  One of these approaches includes the use of calcium hydroxide (Ca[OH] 2 ) that has been widely used as a mineralizing agent as well as an effective antimicrobial medicament since its introduction into dentistry. Despite several newer biomaterials being proposed for pulp capping procedures, Ca (OH) 2 is still considered as the gold standard for comparing and evaluating new products. , Ca (OH) 2 allows for the formation of a reparative dentine bridge through cellular differentiation, extracellular matrix secretion and subsequent mineralization.  Furthermore, a new material, mineral trioxide aggregate (MTA), was developed in the 1990s by Torabinejad et al. at Loma Linda University (California, USA) and has become available as a material used in root canal repair and direct pulp capping.  Various in vitro studies suggest that MTA is biocompatible and has good sealing properties.  Initial clinical studies evaluating the use of MTA as a direct pulp capping material have also shown promising results.  During the setting process, MTA has an initial pH of 10.2, which increases to 12.5 during the first few hours.  Although this pH range is comparable with those achieved by Ca (OH) 2 , there appear to be differences in pulpal tissue reaction to MTA compared with Ca (OH) 2 in direct pulp caps.  Bridge formation tends to be more localized and homogenous (i.e., fewer tunnel defects) with MTA than with those formed by Ca (OH) 2 . 
The success of direct pulp capping depends on several factors. It has been showed that the type of biomaterial selected is of lesser consequence and that the quality of the cavity seal in preventing microbial ingress is the most important factor determining the success of the procedure.  Cox et al.  found that if a bacteria-tight seal is provided, pulpal healing predictably occurred.
For measurements of permeability, several techniques have been used including fluid filtration, scanning electron microscopy (SEM) and dye penetration. These are generally based on a visual evaluation of single or multiple sections  and the specimens must be destroyed during the evaluations. A method of measuring microleakage by the fluid filtration method  overcomes the disadvantages of dye penetration and SEM evaluations. Samples are not destroyed and it is possible to obtain measurements of the microleakage at intervals over extended time periods. In addition, conventional fluid filtration measurements permit quantitative assessments of the leakage for the entire sample.  This technique allows calculations of the leakage by observing the movement of an air bubble inside a micropipette. However, the measurements are relatively subjective since it is sometimes difficult to detect visual readings and follow the minimal movement of an air bubble. The computerized fluid filtration (CFF) method was introduced by Oruηoπlu et al.  This technique depends on the light refraction at the starting and ending positions of an air bubble. An infrared light passes through the micropipette and two light-sensitive photodiodes are put on the opposite sides of the micropipette to detect any movement of the air bubble. All operations are controlled by PC-compatible software (Fluid Filtration 2003, Konya, Turkey).
Most investigations are conducted through an evaluation of clinical and radiographic outcomes or histopathologic observations in human/animal models of pulp capping procedures involving Ca (OH) 2 and MTA. However, few in vitro studies have evaluated the leakage of these capping materials simultaneously. Therefore, the aim of this study was to conduct a laboratory investigation to assess the sealing ability of Ca (OH) 2 and MTA against leakage on direct pulp capping.
| Materials and Methods|| |
In this study, 60 extracted carious-free human molars were used. The occlusal enamel and the superficial dentin of each tooth were removed using a slow speed saw (Isomet, Buehler, Lake Bluff, IL) under water cooling. 60 0.5 ± 0.2 mm thick dentin discs were prepared from dentin just above the highest pulp horn [Figure 1]. The discs were then randomly divided into four groups. The permeability of the dentin varied considerably between and among different teeth. Therefore, the teeth were numbered before performing the tests. The initial permeability of each dentin disc was later used as its own control. The samples were placed in a split-chamber device and fluid movement across each sample was measured. The measurements of fluid conductance were done by following the displacement of an air bubble in a micropipette with a constant barrel (25 μL, 65 mm). During this procedure, a computer program previously described by Oruçoğlu et al.  was used [Figure 2]. The initial fluid conductance for each specimen was also noted.
|Figure 2: Diagrammatic representation of the apparatus used to measure microleakage with the computerized fluid filtration method|
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Simulating perforation and pulp capping
An investigator perforated the dentin discs with the same 1 mm diameter bur. The diameters of the exposed pulps were measured with a stereomicroscope and specimens having inapplicable perforation sizes were eliminated. After the perforation procedure, all specimens were restorated with one of the four commercial pulp-capping materials as follows [Table 1].
A Ca (OH) 2 paste, Dycal (Dentsply Caulk, Milford, USA), was used in the restoration of 15 perforated dentin discs. The base and catalyst of Dycal were mixed and directly applied to the perforated discs as well.
A visible light-cured Ca (OH) 2, Calcimol light-curing (LC) (Voco GmbH, Cuxhaven, Germany), was carried out by the same operator on 15 samples. Calcimol LC was cured for 20 s according to the manufacturer's directions.
Two MTAs, ProRoot MTA (Dentsply Maillefer, Ballaigues, Switzerland) and DiaRoot BioAggregate (DiaDent Europe, Almere, Holland), were used in this study. 15 dentin discs were repaired with ProRoot MTA and another fifteen discs were repaired with DiaRoot BioAggregate according to manufacturers' instructions.
All specimens were then incubated at 37°C for 72 h.
Evaluation of microleakage
After the dentin discs were treated as previously described above with pulp capping materials, the discs were again placed in a split-chamber device and the fluid movement across the dentin was remeasured using the same new CFF meter. Fluid conductance was measured at 2-min intervals for 8 min. The mean of the values obtained was then calculated for each specimen. The linear displacement of the bubble was converted to a volume of liquid filtrated and hydraulic conductance was expressed as micro liters of water flow/cmH 2 O/minute pressure (1.2 atm). The data were calculated for each specimen. Leakage quantity was expressed in μL/cmH 2 O/min−1 and the means were determined.
The results were statistically analyzed by one-way analyses of variance and a Tukey's honestly significant difference post hoc test by specific software (IBM statistical package for the social sciences statistic 20.0 for Mac, IBM Corporation NY, USA). Around 95% of confidence level was used.
| Results|| |
The mean microleakage measurements and standard deviations, in μL/cmH 2 O/min−1 at 1.2 atm, are shown in [Table 2] for all materials. The amounts of the microleakage among the tested materials ranged between 0.849 × 10−4 ± 0.000055-0.192 × 10−4 ± 0.000037 μL/cmH 2 O/min−1 at 1.2 atm. The ProRoot MTA demonstrated the least amount of micro leakage with 0.192 × 10−4 ± 0.000037 μL/cmH 2 O/min−1 at 1.2 atm. The second lowest fluid conductance values were obtained with the DiaRoot BioAggregate with 0.294 × 10−4 ± 0.000038 μL/cmH 2 O/min−1 at 1.2 atm. Dycal and Calcimol LC showed significantly higher leakage results than ProRoot MTA and DiaRoot BioAggregate (P < 0.05).
| Discussion|| |
MTA and Ca (OH) 2 materials have been compared in various studies according to the effectiveness of the direct pulp capping treatments. Previous research suggests that in different animal studies, MTA had significantly better results than Ca (OH) 2 when used as a pulp capping agent. , Dominguez et al.  used light-cured Ca (OH) 2 , MTA and acid-etched dentin bonding as pulp capping agents in dog teeth. Statistical analysis of the data in their study revealed no significant difference between MTA-treated pulps and sound, intact control teeth. Alternatively, significantly more pulpal inflammation was observed in pulps treated with Ca (OH) 2 or bonding agents than in control teeth. Recently, Mente et al.  concluded that MTA performs more successfully than Ca (OH) 2 for maintaining long-term pulp vitality after direct pulp capping in their retrospective clinical research.
However, it has to be remembered that following the pulp capping procedure, bacterial leakage through the restoration material is considered to be the most detrimental reason for poor results. Leye et al.  concluded that maintaining vitality of the pulp after capping procedures requires a good seal of the material. Prevention of bacterial activities with a capping material is very important. When the pulp is perforated, pulp-capping material is expected to completely close the perforation area. It may kill some microorganisms that contaminate the wound surface and it may also protect against the microbial effects of microleakage. For this purpose, Ca (OH) 2 is often used. However, a recent study suggest that pure Ca (OH) 2 and various hard-setting Ca (OH) 2 -containing cements, such as Dycal may not prevent microleakage.  In addition, Murray et al.  reported that the incidence of bacterial microleakage in Ca (OH) 2 -restored teeth was greater than other tested restoratives. In accordance with previous reports, Dycal and Calcimol LC showed the lowest liquid conductance values in the present study. Prosser et al.  claimed that Ca (OH) 2 cements have a non-adhesive nature and exhibit dissolution over time. Farhad and Mohammadi  stated that Ca (OH) 2 is biocompatible, but unfortunately has a low compressive strength when placing definitive restorations like amalgam. This weak and non-durable nature of cements may lead to the increased leakage values observed in the present study. In addition, the light curing Ca (OH) 2 cement, Calcimol LC, showed the highest liquid conductance values when compared with other materials. The present study's results are supported by McConnell et al.  explanations. McConnell et al. reported that when visible light-cured Ca (OH) 2 was placed on the pulpal floor, it tended to form a meniscus curve and left an apparent deficiency on the pulpal floor.
The physical properties of MTA or capping materials might be influenced by crystal size. Smaller particles increase surface contact with the mixing liquid and lead to greater early strength as well as ease of handling.
A study by Komabayashi and Spangberg reported that some particles of MTA are as small as 1.5 μm, which is smaller than the diameter of some dentinal tubules (2-5 μm).  The authors hypothesized that this might play a significant role in the sealing ability of MTA after hydration and production of a hydraulic seal.
Different methods used in studies for assessing leakage include the dye penetration method  electrochemical leakage test and the fluid filtration technique.  In addition to these methods, Oruçoğlu et al. introduced a new CFF method.  This method has some advantages such as being computer controlled, having a digital air pressure arrangement and the ability to follow air bubble movements with laser diodes.  They also claimed that this technique allows quantitative measurements of microleakage without destroying the samples like the fluid filtration technique.
In direct pulp capping, when MTA is chosen because of its advantages such as lower solubility, improved mechanical strength, better marginal adaptation and sealing ability, some of disadvantages of Ca (OH) 2 can be avoided. These disadvantages include resorption of the capping material, mechanical instability and inadequate sealing ability due to leakage.  Most of the studies have involved comparisons with Ca (OH) 2 medicaments and these studies have indicated that MTA is either equally or more successful in pulp capping. However, there are few studies that have investigated the sealing ability of MTA and Ca(OH) 2 when using direct pulp capping materials. Dammaschke et al.  compared MTA and Ca (OH) 2 70 days after capping in rat molars and found there were no differences between MTA and Ca (OH) 2 in the dye penetration results. In spite of the positive properties of MTA, additional research is needed because the numbers of the studies concerning leakage are not adequate.
| Conclusion|| |
Within the limitations of this study, it can be concluded that direct pulp capping with MTA materials seems to be superior to that of Ca (OH) 2 . It should also be kept in mind that further long-term studies are needed to support these results. Furthermore, it is known to what extent leakage of the materials prior to capping might have contributed to the positive results.
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[Figure 1], [Figure 2]
[Table 1], [Table 2]
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