Evaluation of Sealing Ability of Calcium Silicate Materials with Diode Laser for Root Furcation Repair

Introduction

Root perforation can be defined as a mechanical or pathological communication between the root canal system and the external tooth surface.¹ During endodontic treatment, perforations pose severe complications if undetected. It leads to the breakdown of surrounding periodontium, ultimately leading to the tooth loss. Perforations can occur at the floor of pulp chamber, either due to pathological causes such as extensive dental caries, resorption etc., or due to iatrogenic errors during access cavity preparation, post space preparation. In order to prevent the microbial contamination of the root canal and further tissue damage, perforations should be repaired immediately using a biocompatible repair material.

A gamut of materials including zinc oxide eugenol based cements, glass ionomer cements, amalgam, gutta-percha, resin-glass ionomer hybrids, and composite resins have been used to repair furcal perforations.² However, certain limitations of traditional materials include marginal leakage, poor adhesion and bacterial ingress leading to endodontic failure. Therefore, a biomaterial with short setting time and excellent sealing ability should be selected to preserve the tooth, thus increasing the success rate.³

Glass ionomer cement is the commonly employed material for furcal repair. The advantages include limited dissolution in oral fluids, adequate adhesion, acceptable strength and is also available as dual curing cement. However, microleakage has been reported in the furcal perforations repaired with GIC.⁴

Mineral Trioxide Aggregate (MTA) has attracted considerable attention for perforation repair owing to its excellent sealing ability, biocompatibility, regeneration of the tooth structure and surrounding periodontium, in addition to antibacterial action against oral microorganisms. Its drawbacks include poor handling properties, longer setting time and limited antimicrobial activity etc.⁵

The desire for an ideal permanent dentin substitute lead the researchers to develop a calcium silicate based restorative material called Biodentine. It possesses excellent handling properties, biocompatibility, dentin substitution, reparative and regenerative ability along with antimicrobial ability, and hence is recommended for perforation repair.⁶

Laser irradiation of root dentin allows better penetration of irrigants and sealers and enhances adhesion of cements.⁷ Diode laser of 810 to 980 nm wavelength and power levels of 0.8 and 1w causes narrowing and closing of the dentinal tubules without cracks or fissures.⁸ Since there is a scarcity of literature regarding the application of laser activation during furcal perforation repair, this study aimed to evaluate the sealing capability of GIC,MTA and Biodentine as furcation repair materials with and without laser activation using dye leakage model.

Methodology

The present in vitro study was conducted after obtaining Institutional ethical clearance (Reference No-IEC/2021-20/22 S-15). Ninety human mandibular molars extracted due to periodontal problems were collected and stored in 0.5% sodium hypochlorite solution (Prime, Bhiwandi, Maharashtra, India) for 10 minutes in ultrasonic bath to remove organic debris and disinfect the surfaces. All teeth samples were washed under tap water to remove sodium hypochlorite residues. Teeth with well-developed and non-fused roots, intact furcation and root apex were included in the study and teeth with developmental anomalies, fused roots, previous restorations, carious lesions, furcation defects, fractures, cracks and root canal treated teeth were not considered for inclusion in the study.

Sample preparation

Decoronation of the teeth specimens was done using a diamond disk (Kerr Dental, California, USA) using low speed contra angle handpiece (Kerr Dental, California, USA) to obtain vertical tooth section at a level of 3 mm above the cemento-enamel junction (CEJ) and 3 mm below the furcation level. Access opening was prepared in all the specimens using Endo access bur (Dentsply Malliefer, Ballaigues, Switzerland). Sticky wax (DPI, Mumbai, India) was placed over the canal orifice and at the sectioned root surface below as well as the floor of the pulp chamber. To make sure each perforation is centered in between the roots, the furcal defect was marked with a marker pen and a round furcal perforation of 1 mm diameter was prepared from the outer surface of the tooth using a round carbide bur #2 (Dentsply Malliefer, Ballaigues, Switzerland) mounted on a high speed airotor handpiece (NSK, Tokyo, Japan) under saline irrigation (Figure 1A and B).

The pulp chamber and perforations in the specimens were cleaned with distilled water and air dried. The specimens were then randomly allotted into six groups (n= 18 samples each) based on the furcal repair material used.

Group 1: Diode laser activation followed by MTA placement Group 2: MTA (Dentsply, Tulsa, USA)

Group 3: Diode laser activation followed by placement of GIC

Group 4: GIC (GC cooperation, Tokyo, Japan)

Group 5: Diode laser activation followed by placement of Biodentine

Group 6: Biodentine (Septodont, Saint-Maur-des-Fosses, France)

All the experimental materials were mixed according to the manufacturer’s instructions. GIC powder and liquid (1:1 ratio) were mixed on a paper pad with an agate spatula until creamy consistency was obtained. MTA powder was mixed with the provided distilled water (1:3 ratio) until a sandy consistency was obtained and the mix was placed at the perforation site. For Biodentine, the pre-weighed capsules of powder and liquid were mixed in an amalgamator (5:1 ratio) and was placed at the perforation site. In all the groups, the repair materials were condensed with hand pluggers.

In groups 1, 3 and 5, the perforation site was irradiated with diode laser (Ultradent, South Jordan, USA) of 810 nm and power levels of 0.8 and 1w at intermittent mode (Figure 1C). After perforation repair, the specimens in all the groups were kept in humid conditions for about seven days.

Dye penetration evaluation

In each group, the specimens were placed in petri dishes filled with 2% methylene blue solution (Alpha chemika, Mumbai, India) until the specimens were immersed in dye up to the CEJ and dye was also added to access openings of each specimen and kept in solution for about 48 hours at room temperature. The specimens were thoroughly rinsed under running tap water for 30 mins, sectioned mesiodistally with a diamond disc using water coolant. The depth of dye penetration was observed under a stereomicroscope (Labsol enterprises, Gurgaon, Haryana) at 10X magnification to evaluate the amount of microleakage and the data was analyzed using image J software (Figure 2 A-F).

Statistical analysis

The statistical analysis was done using statistical software SPSS version 22 (IBM Corporation, Armonk, NY, USA). One way analysis of variance followed by Post hoc Tukey multiple comparison test was done (p ≤0.05).

Results

The mean and standard deviation of dye leakage values of all groups by one-way ANOVA is shown in table 1.

Highest microleakage of 1.4067 mm was found in group 4 (GIC), followed by group 3 (GIC & Laser) with 1.3100 mm, group 2 (MTA alone) with 0.7113 mm, group 1 ((MTA & laser), group 6 (Biodentine) with 0.4087 mm and the least microleakage of 0.3713 mm was observed in Group 5 (Biodentine and Laser) . Among all the tested materials, laser activation showed less dye leakage (mm) than without laser; however, no significant difference was found between them. Biodentine with laser (Group 5) showed less microleakage which was statistically significant compared to all the other groups, except for group 6 i.e, Biodentine without laser (group 6) at p <0.001 (Table 2).

Discussion

Several materials and techniques have been recommended to repair the furcal defects; however, the effect of diode laser activation on furcal repair was not evident. Hence this study evaluated the sealing capability of GIC, MTA, and Biodentine as furcation repair materials, with and without laser.

Regarding time of perforation repair, previous studies have reported that healing response was good when perforations were repaired immediately and an increase in tissue damage was found in untreated perforations and in those teeth where the sealing of perforation was delayed.³ Therefore, furcal perforations repaired with a biomaterial which is biocompatible with good adhesion properties and sets quickly will be helpful to prevent bacterial ingress and obtain adequate seal, thus increasing the success rate.⁸ Since GIC is the traditional and most used material for furcal perforation repair, it was chosen in this study to compare with MTA and Biodentine. Earlier it was shown that GIC is superior in furcation perforation repair compared to other materials like composites, amalgam.⁸

James et al., concluded that GIC exhibits acceptable sealing ability compared to the conventional materials. However, the results of this study showed that among all the tested materials, GIC exhibited higher microleakage compared to MTA or Biodentine which is in accordance with several other studies that reported MTA exhibiting less microleakage in furcal perforations when compared to glass ionomer cement and resin modified glass ionomer cement which showed more microleakage and less sealing ability compared to MTA cement.^9-11

The results of present study also agree with the findings of the study conducted by Guneser et al., who reported Biodentine to be a superior perforation repair material even after being exposed to various root canal irrigants compared to MTA.¹² Powder component of Biodentine consist of tri-calcium, di-calcium silicates, calcium carbonate and oxide fillers of iron and zirconium. The liquid component comprises of calcium chloride which acts as an accelerator and hydro soluble polymer aiding as water reducing agent. This modern biologically active material can infiltrate through open dentinal tubules to crystallize and interlock with dentin, thereby improving the mechanical properties. Biodentine is formulated similar to MTA-based technology and possess some properties of MTA along with improved physical qualities and handling characteristics with a short setting time of 9-12 minutes, high alkaline pH and is a biocompatible material, thus making an ideal material for perforation repair.^13,14

Atmeh et al., studied the adhesive properties of Biodentine and GIC and determined the presence of interfacial tag like structures along the root dentine. Biodentine caused dentinal collagen degradation and formed adequate adhesion with interfacial tags due to the alkaline caustic outcome of its hydration products.¹⁵ In the present study, Biodentine presented less microleakage when compared with GIC or MTA due to its ability to form the tags within dentinal surface. Han and Okiji stated that calcium and silicon ion uptake into root dentin leads to the formation of tag like structures in biodentine.¹⁶

Less microleakage with Biodentine unlike MTA can be attributed to its modified components, with the presence of accelerators and softeners, and availability of a pre-dosed capsule formulation for accurate and easy mixing. The shorter setting time of Biodentine is an added advantage, thereby sealing the perforation site earlier and further preventing microleakage and microbial contamination, while MTA sets in 3-4 hrs. Hence, microleakage is less with Biodentine with improved early adhesion.¹⁷

Owing to its improved handling properties and smaller particle size, Biodentine adapts adequately to the root dentinal walls, thus improving the sealing ability with less microleakage at the interface. Less porosity was found in set Biodentine, which could also be a reason for better sealing ability.¹⁸ In this study, Biodentine showed the least microleakage among all the materials and is statistically significant and in line with above mentioned studies.

In the present study, among all the materials used for furcation perforation repair with and without laser diode laser irradiation, laser irradiated groups showed less microleakage compared to the non-laser irradiated groups. However, Biodentine with laser was superior compared to MTA and GIC with lasers. This can be attributed to the superior properties of Biodentine adding to the advantages of diode laser activation. Diode lasers exhibit effective antibacterial activity on dentinal tubules with more than 1000 μm penetration into root dentin.¹⁹

Diode lasers also cause thermal photo disruptive action in the unreachable parts of root canal dentin resulting in an enhanced bactericidal effect, allowing better penetration of irrigants, sealers and obturating materials, thus resulting in better adhesion of cements to the root dentin. It was observed that laser pretreatment of dentine surfaces increased the bond strength significantly for both GIC and Biodentine as the dentinal surface produced micro irregularities leading to a high surface wettability, enhancing tag formation.²⁰ Therefore in the present study, the experimental materials GIC, MTA and Biodentine along with laser activation exhibited less microleakage compared to when used without laser activation. However, Biodentine with laser activation was superior among all the groups tested.

Conclusion

Biodentine with laser activation was efficient in furcation repair and decreased the microleakage. However, additional in vitro and in vivo tests and long-term clinical studies are desirable in future for confident use for furcation repair.

Acknowledgement

Nil

Conflict of interest

Nil