|Year : 2018 | Volume
| Issue : 2 | Page : 111-116
Effect of two intracanal medicaments on the sealing ability and push-out bond strength of Biodentine apical plug
Neveen A Shaheen, Walaa M Ghoneim
Department of Endodontics, Faculty of Dentistry, Tanta University, Tanta, Egypt
|Date of Submission||23-Feb-2018|
|Date of Acceptance||26-Mar-2018|
|Date of Web Publication||25-Jun-2018|
Walaa M Ghoneim
Department of Endodontics, Faculty of Dentistry, Tanta University, Tanta
Source of Support: None, Conflict of Interest: None
The purpose of this study was to evaluate the effect of calcium hydroxide (CH) and modified-triple antibiotic paste (mTAP) intracanal medicaments on the sealing ability and push-out bond strength of Biodentine (BD) apical plug.
Materials and methods
A total of 36 human maxillary central incisors were used in this study. Coronal access cavities were made, 3 mm slice of the root tip was resected and root canals were instrumented to simulate immature teeth. Teeth were randomly divided into three groups (n = 12) according to the type of medication used as follow: group 1, CH; group 2, mTAP; and group 3, control group with no medication. After removal of medicaments, BD apical plug was formed in 10 specimens of each group. The sealing ability was evaluated in eight experimental samples of each group while negative and positive samples (n = 4) were used to determine the efficacy of the fluid filtration device by mounting each specimen's root in the fluid transport device and measured by monitoring air bubble displacement in the capillary tube and volume of fluid movement was recorded in μl/min. Then the apical portion of each specimen (n = 8) in all groups was horizontally sectioned to produce 2 mm thick section. Each section was subjected to a compressive load to evaluate push-out bond strength. Data were statistically analyzed using one-way analysis of variance and Tukey test at 5% significance level then Pearson's correlation between sealing ability and push-out bond strength values was performed.
Group 2 showed maximum leakage and the least leakage was recorded for control group with statistically significant difference (P < 0.0001). mTAP recorded the least bond strength value but with no significant difference among three groups (P > 0.05).
The bond strength of BD apical plug to radicular dentine is less affected by medication with CH or mTAP while its sealing ability is significantly affected.
Keywords: Biodentine, calcium hydroxide, modified-triple antibiotic paste, push-out bond strength, sealing ability
|How to cite this article:|
Shaheen NA, Ghoneim WM. Effect of two intracanal medicaments on the sealing ability and push-out bond strength of Biodentine apical plug. Tanta Dent J 2018;15:111-6
|How to cite this URL:|
Shaheen NA, Ghoneim WM. Effect of two intracanal medicaments on the sealing ability and push-out bond strength of Biodentine apical plug. Tanta Dent J [serial online] 2018 [cited 2018 Sep 18];15:111-6. Available from: http://www.tmj.eg.net/text.asp?2018/15/2/111/235130
| Introduction|| |
When pulp necrosis of immature teeth occurs, apical closure, and complete root development cannot be achieved. Root canal treatment at this time presents a significant challenge, because of the large size of the canal, thin and fragile dentinal walls and large open apex. The potential complications associated with endodontic treatment of these teeth include difficulties in achieving complete debridement and optimal sealing of the root canal system . In the absence of a natural apical constriction, the production of mineralized tissue in the apical region is important to create an apical barrier against which filling material can be compacted.
Calcium hydroxide (CH) has been broadly used to induce apexification at the root apex of immature teeth ,. Teeth treated with this material require the placement of long-term CH in the root canal to induce formation of an apical hard tissue barrier. Although multiple visit apexification procedure using CH creates physiological hard tissue barrier, it has several drawbacks like increased duration of treatment procedure , which inturn leads to increased susceptibility of root fracture  and coronal microleakage .
To overcome the drawbacks of traditional CH apexification procedure, placement of artificial hard tissue barrier using different materials has been introduced as alternative treatment. Mineral trioxide aggregate (MTA), as one of the used materials, is a calcium silicate-based powder consisting of fine hydrophilic particles that bind in the presence of moisture. Set MTA provides a good seal and excellent marginal adaptation . Using MTA for apexification shortens the treatment period and improves patient compliance. However, apexification using MTA has some clinical disadvantages like prolonged setting time, manipulation, and handling difficulties .
Other biomaterials such as Biodentine (BD) can be used as alternative apical barrier material. Although it has the same composition like MTA, the poor handling characteristics and prolonged setting time of MTA is overcomed by adding setting accelerators (i.e. CH) and softeners to BD powder which shorten the setting time and facilitate its manipulation .
Disinfection in immature teeth should be achieved with minimum root canal instrumentation. So, it is necessary to use a suitable irrigation and intracanal medicament before placement of the apical barrier to ensure periapical healing . CH is one of the most widely used intrappointment medicament in endodontics, it is a strong alkaline substance with a pH of ~12.5 that dissociates into calcium and hydroxyl ions in an aqueous solution which in turn lead to a lowered oxygen tension and an increased pH in the inflamed periapical tissues excerting an excellent antimicrobial effect .
Infection of the root canal system is considered to be polymicrobial consisting of both aerobic and anaerobic bacterial species. So, several medicaments have been proposed as an alternative to CH. Triple antibiotic paste (TAP) containing metronidazole, ciprofloxacin, and minocycline has been utilized to disinfect the root canal during regenerative endodontic procedures ,. However, the presence of minocycline in TAP has been associated with tooth discoloration ,, so minocycline may be replaced with amoxicillin or cefaclor forming modified-triple antibiotic paste (mTAP).
The sealing ability of apical plug materials is an important factor for successful endodontic treatment in immature teeth. Various methods can be used to assess leakage around apical plug, such as dye penetration, light microscopic methods, fluid filtration method, and scanning electron microscope (SEM), however, fluid filtration method has an advantage as it can quantify the amount of microleakage while other methods can only show the presence or absence of microleakage. In addition, it is noninvasive method in which sample remains intact for future analysis, permitting the evaluation of sealing efficiency over time .
Previous studies , showed that intracanal medicaments cannot be completely removed from the root canal walls using existing irrigation techniques. Any remnant of intracanal medicaments may cause alteration in the chemical and structural composition of root canal dentin  which intern will affect the chemical adhesion and penetration properties of endodontic materials.
Limited information is known about the potential effect of intracanal medicaments on the sealing ability and bonding effectiveness of BD apical barrier in immature nonvital teeth. Therefore, the purpose of the present study was to evaluate the effect of two intracanal medicaments (CH, mTAP) on sealing ability and push-out bond strength of BD apical plug and find any possible statistical correlation between them.
| Materials and Methods|| |
A total of 36 freshly extracted human maxillary central incisors were used in the current study. All patients were informed about the purpose and steps of this research and written consents were signed for using their extracted teeth in the research according to the Research Ethics Committee of Faculty of Dentistry, Tanta University. These teeth were extracted due to periodontal reasons. The selection criteria depended on confirmation of the preoperative radiographs of the absence of previous root canal treatment, resorptions, or calcifications. The teeth were immersed in 5.25% sodium hypochlorite (NaOCl; Clorox Company, 10th of Ramadan, Egypt) solution for 5 min to remove any organic components from the root surfaces; periodontal tissue and calculus were removed with a hand scaler. Coronal access cavity was made using a size 3 round bur (Dentsply Maillefer, Tulsa, Oklahoma, USA) and Endo Z bur (Dentsply Maillefer, Ballaigues, Switzerland) using high-speed contra angle handpiece under water cooling. A 3 mm slice of each root tip was resected using a straight fissure bur (Dentsply Maillefer, Tulsa, Oklahoma, USA) under water cooling and working length was determined by measuring a size 10 K-file (Mani, Tochigi, Japan) which was advanced into the canal until it was just visible at the apex and then subtracting 1 mm from this length. All specimens were instrumented with ProTaper Universal rotary files (Dentsply Maillefer, Ballaigues, Switzerland) up to F5 (#50/0.05) according to the manufacturer's protocol to the full working length. Irrigation was done by using 5 ml of 2.5% NaOCl between each instrument, using a 30-G closed-end needle (NaviTip; Ultradent Inc., South Jordan, Utah, USA). A standardized open apex was created by means of Peeso drills (Mani) #1 to #6 in a way that drill #6 was allowed to pass 1 mm beyond the apex. All canals were finally irrigated using 5 ml of distilled water.
Grouping of samples
Teeth were randomly divided into two experimental groups and one control group (n = 12) according to the intracanal medicament used as follow:
- Group 1: CH paste was prepared by mixing CH powder (Sultan; Lider, Istanbul, Turkey) with distilled water in powder/liquid ratio of 2: 1 to obtain thin creamy mix. It was applied by a lentulo spiral (Dentsply Maillefer, Ballaigues, Switzerland) installed on low speed handpiece (NSK, Tokyo, Japan)
- Group 2: mTAP was prepared with powder to liquid ratio of 3: 1 according to the study by Hoshino et al. . Powder is made by taking equal amounts of commercially available forms of metronidazole (Flagyl tablets; Sanofi Aventis, El Amiriya, Egypt), ciprofloxacin (Cipro tablets; European Egyptian Pharm, Alexandria, Egypt) and cefaclor (Cefaclor capsules; Pharco B International, Alexandria, Egypt) while liquid is propylene glycol (El Gomhoria Co. for trading pharmaceuticals, SAE, Egypt). Before mixing, it is important to ensure that metronidazole and ciprofloxacin tablets are ground into a fine powder while cefaclor is available in capsule form that needed to be opened and grounded to give the paste a cream-like consistency. After mixing, the paste was applied in the same manner as in group 1
- Group 3: control group (no medicament).
After application of the intracanal medicaments, the root canal accesses were sealed using a cotton pellet and Cavit temporary filling material (3M ESPE, Seefeld, Germany) and the samples were kept for 3 weeks at 37°C under 100% relative humidity. Then the temporary filling material and the cotton pellet were removed from the access cavities and intracanal medicaments were removed from the canal by light instrumentation using size 50 K stainless steel hand file (Mani) that was introduced to the working length and gently manipulated to remove the paste. This removal procedure was accompanied with irrigation by 5 ml of 2.5% NaOCl and a final flush with 5 ml of 17% EDTA (Pulpdent, Watertown, Massachusetts, USA) for 1 min. Finally, the root canals were rinsed with distilled water and dried using paper points (DiaDent, Chongju City, Korea).
BD apical plug was formed in 10 specimens of each group as follows, five drops from a single-dose container of BD (Septodont, Saint-Maur-des-Fosses, France) liquid was emptied into a powder containing capsule and mixed for 30 s in an amalgamator (Softly 8; de Gotzen, Roma, Italy) according to the manufacturer's instructions. Its mix was then applied with an amalgam carrier and adapted to the canal walls using a prefitted hand plugger (Dentsply Maillefer, Ballaigues, Switzerland) shorter than tooth length by 4 mm to obtain a 4 mm apical plug. A saline-moistened gauze pad was used to prevent over extrusion of BD during condensation. Butt-end of a paper point was used to remove any excess material from the canal walls. Radiographs were taken to ensure proper placement and thickness of BD apical plug then the hardness of BD was verified after 12 min using hand plugger to confirm its set and teeth were stored at 100% humidity and 37°C for 1 week to ensure complete setting of BD.
Finger nail varnish was applied to the external surface, excluding the resected root surface in eight experimental samples to prevent side leakage through the dentinal tubules. The negative and positive samples (n = 4) were used to determine the efficacy of the fluid filtration device. Two layers of nail varnish were applied over the entire surface of the root and BD plug (n = 2) in the negative control group while BD plug was not placed in the positive control group (n = 2).
Evaluation of sealing ability
Each root was mounted in the fluid transport device [Figure 1] as described by Wu et al. . The sealing ability of the apical plug were measured by monitoring the displacement of the air bubble in the capillary tube and the volume of fluid movement was recorded in μl/min according to the following formula ,:
Where P is the applied pressure in Pascal; L is the length of bubble movement in meter; r is the radius of the micropipette in meter; ή is the viscosity of the fluid in Pascal per se cond (Pa-s).
The pressure used was 0.6 atm (0.6 × 105 Pa) and the viscosity of water is 10-3 Pa-s.
Push-out bond strength test
The apical portion of each specimen (n = 8) in all groups including apical plug was horizontally sectioned perpendicular to the long axis of the root using a slow-speed, water-cooled diamond disc (Komet; Brasseler, Lemgo, Germany) to produce ~2 ± 0.1 mm thick section. Loading was applied using a 1 mm diameter custom-made stainless steel cylindrical plunger, contacting BD only, mounted on the upper member of universal testing machine (Lloyd Instruments Ltd, Fareham, UK) in apical to coronal direction. The force was applied at a cross head speed of 1 mm/min until bond failure occurred. The bond strength at failure was calculated in megapascals (MPa) by dividing the load in Newton (N) by the area of the bonded interface using the following formula :
Push-out bondstrength (MPa) = F/A
F = maximum load (N)
A (adhesion surface area in mm 2) = πh (r1+r2)
Where, π is the constant 3.14; r1, apical radius; r2, coronal one; and h is the thickness of the slice in millimeters.
Mean values and SD for both leakage and push-out bond strength test were calculated and statistically analyzed using one-way analysis of variance. Whenever statistical significant difference was recorded among groups, multiple pairwise comparisons were performed using Tukey's post-hoc test using SPSS statistical software (version 20; SPSS Inc., Chicago, Illinois, USA); P values less than or equal to 0.05 were considered to be statistically significant. Then Pearson's coefficient (r) was performed to pick up a statistical correlation between sealing ability and push-out bond strength.
| Results|| |
Results of fluid filtration and push-out bond strength values in μl/min and MPa, respectively, were presented in [Table 1]. Considering fluid filtration test, no leakage was observed in the negative control samples because no movement of the bubble was observed while in the positive controls, the air bubble moved rapidly and interruptedly along the capillary tube as soon as the pressure was applied so it was considered to be 100% leakage.
|Table 1: Fluid filtration values and push-out bond strength (mean±SD) of Biodentine with respect to intracanal medicaments used|
Click here to view
The tested intracanal medicaments and control group (with no medicaments) exhibited different amounts of leakage. In group 2 where mTAP was used as an intracanal medicament, it recorded the highest mean value expressing the maximum leakage followed by group 1 in which CH was used and the least leakage was recorded for group 3 (control group) with statistically significant difference between the three studied groups (P < 0.0001). Pairwise comparisons showed that control group was significantly different than both experimental groups.
Regarding the results of bond strength, the current data showed that the intracanal medicaments tested had nonsignificant effect on the push-out bond strength of BD apical plug (P = 0.212) where mTAP recorded the least bond strength value in comparison to CH and the control group.
Mean values with the same superscript letters within the same column showed no statistical significant difference verified by one-way analysis of variance and Tukey's test (P ≤ 0.05).
Pearson's correlation between fluid filtration volume and push-out bond strength values were shown in [Figure 2]. A negative nonsignificant correlation was observed between sealing ability and push-out bond strength values (r=−0.217, P = 0.437). This means that intracanal medicament which recorded lower leakage value also resulted in higher bond strength.
|Figure 2: Scatter plot representing the correlation between fluid filtration volume and push-out bond strength.|
Click here to view
| Discussion|| |
BD has been recommended for creating an artificial apical barrier in teeth with open apices because of its excellent biological properties and ability to create a good seal . The fluid filtration method was used in this study because it is a reliable technique to quantitate the measurement of microleakage of the filling materials or apical seal, allowing repeated measurements without destruction of the samples and very small leakage volume can be recorded .
However, there are various methods for evaluating the adhesion of a dental material to dentin including tensile, shear, and push-out strength tests, push-out test has been demonstrated to be a reliable, efficient, and practical method to assess bond strength to root canal dentin .
Summarizing the results of this study, it was found that CH and mTAP intracanal medicaments definitely affect the sealing ability of BD when used as an apical plug as the control group without intracanal medicaments exhibited a significantly lower leakage value compared with the tested intracanal medicament groups. This may be attributed to that CH intracanal medication cannot be removed completely from the root canal . Similarly, mTAP cannot be effectively removed from the root canal system using the current irrigation techniques because of its penetration and binding capacity .
Residues of medicaments may decrease the micromechanical interlocking properties which deteriorates the integrity of the sealer-dentin interface  as these remnants act as a physical barrier between radicular dentin and root canal sealer and negatively affecting its penetration into dentinal walls ,.
According to SEM examination, mTAP premedicated group showed excessive erosion of the dentinal tubule orifices, along with excess remnants of the antibiotics while CH treated group demonstrated dentinal tubules with a slight erosion of the orifices and less remnants of the CH . These findings may explain why group 2 premedicated with mTAP had more leakage and lower push-out bond strength values than CH premedicated group in the present study.
These results are supported by Adel et al. and Stefopoulos et al. who showed that intracanal CH therapy had adverse effects on sealing properties of MTA apical plug. However, it was in disagreement with Bidar et al.  study in which they concluded that CH as interappointment intracanal medicament had no adverse effect on the sealing properties of calcium silicate-based cements and this may be attributed to different methodology in which the apical portion of teeth were immersed in sulfuric acid to produce resorption and simulate immature teeth. In addition, marginal adaptation was evaluated by measuring the gaps between the material and dentin walls using SEM.
According to the results of the current study, using of CH as intracanal medication positively increase bond strength of BD apical plug to radicular dentin with no significant difference among the three groups. This may be explained by effect of medicaments residues. As chemical reaction of BD with CH residues may improve marginal adaptation of calcium silicate-based cements . These results are in agreement with Nagas et al. , who showed that prior placement of CH increases the push-out bond. In addition, Felippe et al. , found a similar positive effect of CH residue on the bond strength of a calcium silicate-based sealer to dentine. On the other hand, a study by Akman et al. , reported that CH intracanal medicament reduces push-out bond strength of BD which may be explained by difference in methodology in which the apical parts of the teeth were horizontally sectioned into 1-mm thick slices to obtain 2–3 dentin discs and then the tested materials (Biodentine and DiaRoot BioAggregate) were applied into the discs.
It was important to evaluate the presence of any possible statistical correlation between fluid filtration expressing leakage and push-out bond strength expressing adhesion strength of BD apical barrier in the current study. The results showed that there was nonsignificant negative correlation between fluid filtration volume and bond strength. This means that whenever leakage volume decreased, the bond strength increased. This finding may be attributed to that BD apical plug has been proposed to adhere properly to radicular dentin whatever the pretreatment intracanal medicament used, which in turn reduce microleakage.
| Conclusion|| |
Using of intracanal medication of either CH or mTAP has a significantly adverse effect on the sealing ability of BD apical plug. On the other hand, the adhesion strength of BD apical plug to radicular dentine is less affected by prior medication with CH or mTAP.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]