Comparative evaluation of the efficacy of diode laser, EndoActivator, passive ultrasonic irrigant, and manual irrigation activation systems in debridement of root canal isthmus: An in vitro study

Abstract

INTRODUCTION For an endodontic therapy to be successful, accurate diagnosis, cleaning and shaping accompanied by sterilization and sealing of the endodontically-treated teeth is necessary.[12] At least two-third remained uninstrumented in the canals when mechanical instrumentation alone was used. Hence, it is imperative in identifying the irrigation methods that can help in the removal of these remnants to improve the clinical success.[3] Employing the routine needle irrigation method could not completely eliminate the remnants from the root canal areas where additional lateral canals, isthmi, and fins were present.[4] Isthmus is a thin, ribbon-shaped connection joining two canals of the root that has the presence of pulp tissue. The presence of isthmuses has been found in roots wherein two canals are present. Studies have shown that the number of isthmuses increased at the apical 5 mm of the root.[123] EndoActivator (Dentsply Tulsa Dental Specialties) activates irrigants with strong, flexible tips and is available as a cordless sonic handpiece. Several studies have proved its superior ability.[5678] Passive ultrasonic irrigation (PUI) is another means for agitation of irrigating solutions.[9] Weller et al. were the first to employ it in 1980.[1] The irrigant uses the ultrasonic wave energy which passes through the file.[1] Manual dynamic activation (MDA) necessitates recurrent placing of tight-fitting gutta-percha cones (Dentsply) in a preenlarged canal up to its working length. It is a cost-effective method when compared to modern irrigation activation systems.[2] The use of Er:YAG laser assisted irrigation[10] and 980 nm diode laser (Denlase, China), which provides effectual delivery of laser light to the canal walls to help in the total depletion of bacterial colonies, possesses optic fibers which are in the diameter of 200–320 μm.[2] The use of a scanning electron microscope for examining isthmus cleanliness at the apical region was difficult, and thus, the use of stereomicroscope (Nikon SMZ25) was employed to evaluate the isthmus area at the apical region.[7] Hence, the aim of the current in vitro study undertaken was to comparatively evaluate the cleaning efficiency of diode laser, EndoActivator, PUI, and MDA on the debridement of root canal isthmus using a stereomicroscope. MATERIALS AND METHODS The ethical clearance was obtained from the ethical committee, Navodaya Dental College, Raichur. Sixty-five extracted human permanent mandibular first molars were selected for the study. Each tooth was radiographed to ensure the presence of fully formed canals. Inclusion criteria Teeth that had been extracted for periodontal reasons Teeth having deep caries Teeth having fully formed roots. Exclusion criteria Exclusion criteria included teeth with immature roots or having single roots, calcified canals, root canal treated, canals having internal resorption, and fractured instruments. All teeth were cleaned, disinfected, and stored in normal saline for a period of 2 days. Access cavity preparation was done, and the patency was established using a no. 10 K file (Dentsply Maillefer, Ballaigues, Switzerland) in each canal. The initial canal preparation was achieved with hand files #15 and #20 K. The ProTaper rotary system (ProTaper Gold, Dentsply Maillefer, Ballaigues, Switzerland) was used for canal preparation and each canal was prepared up to an apical preparation of F2 size with a taper of 6%. Irrigation was done using 5.25% sodium hypochlorite (NaOCl) (Vista) after each file using a 30-gauge side-vented needle. Then, the experimental teeth samples were distributed randomly into five groups having 13 samples each. The final irrigation was carried out for all the experimental groups as per the following protocol or regimen. Group 1 (Diode laser) – Following irrigation using 5.25% sodium hypochlorite, the fiber optic tip (diameter = 200 μm/980 nm) of the diode laser (Denlase, China), in the continuous wave mode, was introduced till 1 mm short of the apex and was recessed in helicoidal motion at a speed of approximately 2 mm/s for 5 s, repeated four times at intervals of 10 s.[23] Group 2 (EndoActivator) – The canals and pulp chambers were filled with 5.25% sodium hypochlorite (NaOCl). The EndoActivator sonic handpiece (Dentsply, Tulsa dental specialties) having a size no. 25/0.04 taper activator tip was set at 10,000 cpm and was passively inserted into the canal up to 2 mm of the working length. The tip was moved in short 2–3 mm vertical strokes for a period of 60 s at a medium speed.[1] Group 3 (PUI) – Final rinse with 5.25% sodium hypochlorite (NaOCl) was activated with a #20 tip (Cricendo, China) which was driven by an ultrasonic device (EMS) with power set at 5 for 1 min at 1 mm from the working length.[1] Group 4 (MDA) – In this group, the irrigant was agitated with the aid of a master cone gutta-percha point (ProTaper F2, Dentsply). The irrigant was introduced in the canal with a 27-gauge needle. The GP cone was used in short, vertical strokes to stimulate the irrigant. The irrigant solution was activated in the canal for 1 min (100 strokes/min).[1] Group 5 (Control): No activation of the irrigant was done in this group.[1] Following the irrigation activation, distal roots were separated and the mesial root was cut longitudinally 4 mm from the apex. According to Kang et al.[11] and Karunakaran et al.,[12] the presence of isthmus was more at 3–5 mm from the apical region in the mesial root of lower first molars. Specimen evaluation The images of each section were taken with a Nikon digital camera attached to a stereomicroscope and the images were viewed on the computer. The sections were viewed at ×20 [Figure 1].Figure 1: Isthmus cleanliness after (a) Endoactivator, (b) Diode Laser, (c) Ultrasonic devise, (d) MDA group, (e) Control groupThe following scoring criteria were used:[1] Score 1 – Clean root canal walls, only a few small debris particles Score 2 – Few small agglomeration of debris Score 3 – Many agglomerations of debris covering <50% of the root canal wall Score 4 – More than 50% of the root canal wall covered with debris Score 5 – Complete or nearly complete root canal walls covered with debris. Statistical analysis The images of each section were taken with a Nikon digital camera attached to a stereomicroscope and the images were viewed on the computer. The sections were viewed at ×20. The software program ImageJ (v1.43; National Institutes of Health, Bethesda, MD) was used to calculate the amount of debris present in each sectioned tooth sample of the respective groups and their total average was calculated. Statistical analysis was done using ANOVA and post hoc Tukey's test for intergroup comparison. RESULTS Of 13 (100%) samples in each group, the EndoActivator group showed a lower debris score of 1 and MDA group showed the highest debris score of 3 [Table 1].Table 1: Cross-tabulation of the debris scorePost hoc Tukey was applied to compare the mean difference between the groups. Post hoc Tukey test showed a statistically significant difference between MDA and EndoActivator; MDA and control group; PUI and control group; EndoActivator and diode laser; EndoActivator and control group; and diode laser and control group [Table 2].Table 2: Post hoc TukeyDISCUSSION The main objective of endodontic therapy is to completely sterilize the root canal system, which involves the revocation of microorganisms and microbial constituents and halt the reoccurrence of infection.[41011121314] Higher frequency of isthmus was detected in molars located in the mandibular region.[131516] The present study checked for debridement of the isthmus, mainly type 2, which according to Kim's classification, showed a definite communication between the two canals. Recent studies have suggested the existence of an isthmus at 2 mm to 5 mm from the apical region, revealing that these spaces may be a concern during nonsurgical root canal treatment.[13] The results of the current in vitro study illustrated that EndoActivator when used to activate the final irrigant showed the least amount of debris when compared to diode laser, passive ultrasonic irrigant, and manual activation method.[13171819] The study was in agreement with several studies wherein the EndoActivator showed better efficacy.[18] In the present study, EndoActivator showed 53.8% cleanliness of isthmus areas when compared to diode, PUI, and MDA techniques. EndoActivator has been designed to safely and potently energize intracanal irrigants employing sonic energy. It generates fluid hydrodynamics which improves the debridement, thus helping in the elimination of the debris layer and microbes.[118] Another method for activation of irrigants is by the application of lasers. In a study by Gutknecht et al., the use of diode laser helped in the overall success of the endodontic treatment. The transmission of laser light inside the canal walls does provide an antibacterial effect. Thus, diode laser has been equipment worth testing.[5] Better efficacy in debris removal has been achieved when the irrigant was agitated using the sonic and ultrasonic mechanisms. PUI depends on the transmission of acoustic energy from an oscillating file to an irrigant present in the canal. This energy is transmitted by ultrasonic waves and can induce acoustic streaming and cavitation of the irrigant. Numerous researches have revealed that PUI to be less effective when compared to EndoActivator which was consistent with the outcome of the present study.[146] The hydrodynamic activation could be one of the possible reasons for superior outcomes in the EndoActivator group. CONCLUSION Within the limitation of the current study, it was concluded that the EndoActivator system showed greater cleanliness at the isthmus level of mandibular molars when compared to diode laser, passive ultrasonic irrigant, and MDA systems. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.