BRIEF RESUME OF INTENDED WORK
6.1 Need for the study:
Debridement of the root canal system is mandatory for endodontic success1. While the instruments shape and widen the root canals, the irrigating solutions act by dissolving organic tissue (vital or necrotic) and removing debris and microorganisms. The pool of dentin chips, pulp remnants and other particles that remain loosely attached within the intracanal space after biomechanical preparation in areas that were not accurately cleaned by action of chemical solutions and endodontic files is called debris. The amorphous structure composed of dentin debris, organic material and microorganisms that is produced by mechanical instrumentation and adhere to the root canal walls obstructing the dentinal tubule openings constitutes the smear layer2. The physicochemical action of NaOCl is limited to the removal of organic particles whereas chelating agents such as EDTA act on the inorganic debris formed in instrumented root canals3.
The flushing action of the irrigant may be enhanced by using ultrasound wherein the irrigant is activated by ultrasonic energy resulting in the phenomena of acoustic streaming and eddies4. Besides ultrasound, addition of surfactants may increase the penetration of irrigating solutions into the apical third of root canal and dentinal tubules. A low surface tension enhances the wettability of the solution on dentinal walls5. SmearClear is a 17% EDTA solution which includes a cationic (cetrimide) and an anionic surfactant, launched by SybronEndo (Orange, CA) for better removal of smear layer6.
Several new agitation devices have been introduced as proposed armamentarium to effectively clean the root canal system and replace ultrasonic agitation7. One of such innovations is the F-file, a presterilized, single-use, plastic rotary file with a unique design which has a diamond abrasive embedded into a nontoxic polymer. It was designed to remove dentinal wall debris and agitate the NaOCl solution without further enlarging the canal. The file has a 0.04 taper and the file tip is equivalent to a size #20 K file. The F-file was hailed as a possible replacement for sonic and ultrasonic instrumentation8.
NaviTip FX (Ultradent, UT), recently introduced to the market, is a 30-gauge irrigation needle covered with a brush. Studies have shown that the use of NaviTip FX in a manual brushing action shows greater efficacy in cleaning the root canal walls9.
This SEM study aims to evaluate the effectiveness of removal of debris and smear layer from prepared root canals by comparing the techniques of ultrasonic agitation, F-file agitation, and NaviTip FX needle agitation using NaOCl and SmearClear as irrigants.
6.2 Review of literature:
A study was conducted to evaluate the efficacy of a handpiece-mounted irrigation device and compare it to irrigation with a syringe and needle in the apical 5 mm of the root canal system. Twenty matched pairs of extracted teeth were used. The only variable within each matched pair was the method of irrigation. A syringe and needle were used in group A and the handpiece-mounted system in group B. Sections 1, 3 and 5 mm from the working length were examined microscopically, and images of the slides were digitized. There was no significant difference in the amount of debris remaining in the apical 5 mm of canals when comparing the two methods of irrigation10.
A study was done to evaluate canal cleanliness and smear layer removal after use of the Quantec-E irrigation system and to compare the system with traditional irrigation. Irrigation with the Quantec-E irrigation pump resulted in cleaner canal walls, less debris, and more complete removal of the smear layer within the coronal one third, when compared with syringe irrigation. No difference was observed in the middle and apical one thirds. It was concluded that there was no significant difference between the two irrigation systems11.
In a study to evaluate, in vitro, with scanning electron microscope, the appearance of root canal walls shaped by three different rotary NiTi techniques and one conventional manual technique in human extracted teeth, it was concluded that mechanical rotary techniques with NiTi instruments produced quite similar results compared with a conventional manual technique using K-files. The study demonstrated that dentin and pulpal debris, the morphology of smear layer and surface profile were only partially influenced by the type of endodontic instruments. The apical third was the anatomical area with greater amount of debris and smear layer12.
In a study to compare the ability of syringe irrigation and ultrasonic irrigation for removing artificially placed dentine debris from simulated canal irregularities within prepared root canals, it was concluded that ultrasonic irrigation ex vivo is more effective than syringe irrigation in removing artificially created dentine debris placed in simulated uninstrumented extensions and irregularities in straight, wide root canals4.
A study to assess the presence of apical debris remaining in the apical third of flattened root canals of vital and nonvital teeth after biomechanical preparation with Ni-Ti rotary instruments concluded that the clinical condition of pulp tissue did not interfere with the amount of debris remaining in the apical third of flattened root canals prepared with Ni-Ti rotary instruments2.
A study compared the in vitro efficacy of SmearClear, a 17% EDTA solution with surfactants, to 17% EDTA with and without the use of ultrasonics, in removal of the smear layer. Samples were examined under SEM and scored for debris and smear layer removal. It was concluded that addition of surfactants to EDTA in SmearClear did not result in better smear layer removal. The use of ultrasonics with 17% EDTA improved smear layer removal5.
In a study to compare the efficacy of the EndoVac irrigation system and needle irrigation to debride root canals at 1 and 3 mm from working length, it was shown that there is significantly better debridement at 1 mm from working length by using the EndoVac compared with needle irrigation1.
A study to compare the efficacy of SmearClear, 17% EDTA, and 10% citric acid in smear layer removal concluded that the protocol used in the study was not efficient to completely remove the smear layer especially in the apical third of the canal6.
A SEM evaluation to compare the effectiveness of F-files and ultrasonics to remove the smear layer from instrumented root canals when irrigated with NaOCl and EDTA revealed that there appeared to be little difference between the F-file and the ultrasonically activated #20 K file in removal of the smear layer with or without EDTA8.
In a study aimed to evaluate the efficacy of SmearClear and EDTA for smear layer removal from root canals of permanent teeth after instrumentation, it was concluded that SmearClear was able to remove the smear layer from the root canals of permanent teeth similarly as 14.3% EDTA, suggesting that both solutions may be indicated for such purpose3.
An in vitro study compared 3 agitation and 2 irrigation devices to ultrasonic agitation at mechanically removing bacteria from a plastic simulated canal, instrumented to 35/.06. It was concluded that in a plastic simulated canal, ultrasonic agitation was significantly more effective than needle irrigation and EndoVac irrigation at removing intracanal bacteria. Ultrasonic, EndoActivator, F-file, and sonic agitation are similar in their ability to remove bacteria in a plastic simulated canal7.
A study evaluated the effectiveness of the NaviTip FX in removing debris and smear layer in vitro. It was seen that in moderately curved root canals, a NaviTip FX used with 5.25% NaOCl and 17% EDTA solution with manual brushing as well as the same method augmented by FileEze was the most effective cleaning protocol9.
6.3: Objective of the Study:
To evaluate, with scanning electron microscope, the effectiveness of removal of debris and smear layer from prepared root canals by comparing the techniques of ultrasonic agitation, F-file agitation, and NaviTip FX needle agitation using NaOCl and SmearClear as irrigants.
MATERIALS AND METHODS:
7.1 Source of Data :
SOURCE OF DATA
The study will be performed on bilaterally matched extracted human premolars.
Handpiece (NSK, Nakanishi Inc.)
Diamond disc (MDT Micro Diamond Technologies Ltd)
# 10 K files ( Mani)
K3 rotary files (SybronEndo, Orange, CA)
0.9% normal saline
2.5% NaOCl solution freshly prepared
SmearClear (SybronEndo, Orange, CA)
Max-i-Probe irrigating tips 25-gauge and 30-gauge (Dentsply MPL, Elgin, IL)
Paper points (Dentsply)
Satelec ultrasonic unit ( Suprasson P Max)
F-files 0.04 taper and 0.06 taper ( PlasticEndo, Buffalo Grove, IL)
NaviTip FX (Ultradent Products Inc, South Jordan, UT)
Scanning electron microscope
7.2: Method of collection of data ( including sampling procedure, if any):
60 bilaterally matched pairs of extracted, single-rooted human premolar teeth with single canal and mature apices will be collected. The presence of a single canal will be verified with two digital radiographs in a mesiodistal and a buccolingual direction. All teeth will be decoronated at the cementoenamel junction using a diamond disc. Canal patency will be confirmed for each tooth by inserting a #10 K-file beyond the apical foramen. Working length will be established by measuring the length at which the #10 file is first visible in the apical foramen and subtracting 0.5 mm. In each sample the teeth will be grooved longitudinally with a diamond disc on the buccal and lingual surfaces to facilitate vertical splitting with chisel and mallet after instrumentation and to prevent further contamination. To avoid creating artificial debris, the disc will not be allowed to penetrate the canal space.
After determining the working length, all teeth will be instrumented in a crown-down manner using K3 rotary files. For groups 1, 2 and 3, 2.5% NaOCl will be the irrigant during instrumentation. For groups 4, 5 and 6, SmearClear will be the irrigant during instrumentation.
After instrumentation, the matched pairs of teeth will be divided as follows.
Group 1: 10 teeth from each matched pair will undergo ultrasonic agitation of 2.5% NaOCl for 30 seconds 2 mm short of the apex in short cyclic axial motion in low speed.
Group 2: 10 teeth from each matched pair will undergo F-file agitation of 2.5% NaOCl for 30 seconds in a short circumferential cyclic axial motion.
Group 3: 10 teeth from each matched pair will undergo manual left and right rotary motion combined with up and down movements, applying a brushing action on the dentin walls with the NaviTip FX for 1 minute continuously under irrigation with 2.5% NaOCl.
Group 4: Pairs of the 10 teeth used in group 1 will undergo the same procedure followed in that group but under irrigation with SmearClear.
Group 5: Pairs of the10 teeth used in group 2 will undergo the same procedure followed in that group but under irrigation with SmearClear.
Group 6: Pairs of the 10 teeth used in group 3 will undergo the same procedure followed in that group but under irrigation with SmearClear.
All the teeth will be rinsed with 0.9% saline. The canals will be dried with paper points. The roots will then be split into two halves with a chisel and mallet. The half with the most visible part of the apex will be used for scanning electron microscopic evaluation. SEM micrographs will be obtained at 1,000X magnification of the coronal, middle, and apical areas of each root canal. The amount of debris and smear layer scored will be evaluated using a three-step scale.
Score-1: no debris or isolated small particles present.
Score-2: debris covering 50% or more of the canal walls.
Score-3: debris covering the entire canal walls.
For smear layer,
Score-1: a regular pattern of open dentinal tubules and no smear layer present.
Score-2: some open dentinal tubules, and the rest covered by smear layer.
Score-3: a continuous smear layer covering the canal walls, and no dentinal tubules seen.
The average scores of each level, viz. coronal, middle, and apical, will be calculated by dividing the sum of all individual scores by the number of evaluation units. The mean scores for debris and smear layer will be calculated for each tooth and for each group and statistically analysed using the Kruskal-Wallis test, Friedman test, Mann-Whitney test, and Wilcoxon signed rank test.
7.3: Does the study require any investigation or interventions to be conducted on patients or other humans or animals? If so, please describe briefly.
Yes, human premolar teeth extracted for orthodontic reasons will be used in the study.
7.4: Has ethical clearance been obtained from your institution in case of 7?