“COMPARISON OF CLEANING ABILITY OF TWO ROTARY SYSTEMS AND MANUAL K-FILE INSTRUMENTS IN PRIMARY MOLAR ROOT CANALS- IN VITRO STUDY”
Brief resume of intended work
Need for the study
The pulpectomy procedure for restorable primary teeth is the preferred treatment of infected pulpal tissue in single rooted teeth and in molars with signs of furcal, radicular involvement. Prior to the placement of pulpectomy paste, the root canals of primary teeth will be shaped and cleansed1. The primary objectives of cleaning and shaping the root canal system is removing soft and hard tissue containing bacteria, providing a path for irrigants to the apical third, supplying space for medicaments and subsequent obturation, retaining the integrity of radicular structure. Thus success of pulpectomy depends on elimination of irritants by means of cleaning and shaping the root canal. This has traditionally been done with files, reamers and sonic instruments. Recently nickel-titanium rotary files have been used for canal preparation in primary teeth2. The design and flexibility of Nickel Titanium alloy instruments allow files to preserve the original anatomy of curved canals especially in primary teeth and reduce procedural errors. In addition because of the funnel shaped canal preparation a more predictably uniform paste filling can be obtained in primary teeth. Rotary files also favor the patient’s cooperation by shortening treatment time for cleaning canals3. Limited literature exists regarding Nickel Titanium rotary endodontic system in pulpectomy of primary teeth. Most researchers have tested these instruments only in permanent teeth3. Thus the objective of this in-vitro study is to compare the cleaning ability of the two rotary systems i.e micromega and protaper with manual instruments in primary molars.
6.2Review of literature
Traditional way of shaping root canal by use of stainless steel hand files has several drawbacks. They require the use of numerous hand files and the technique is time consuming4.
Nickel titanium rotary files are used for root canal instrumentation in primary teeth. Recently nickel titanium rotary files have been developed for use in Pediatric endodontics. The flexibility and the instrument design allow the files to closely follow the original root canal path. The same principles of canal debridement and dentin shaping using Nickel Titanium used for permanent teeth can be applied for primary teeth as well. The tortuous and irregular canal walls of primary molars are effectively cleaned with Nickel Titanium since the clockwise motion of the rotary files pulls pulpal tissue and dentin out of canal as the files are engaged. A study conducted by Barr ES, Kleir DJ, Barr NV suggest the use of Nickel Titanium and consider it a more effective way to debride the uneven walls of primary teeth. The use of rotary instrumentation for primary teeth pulpectomies has proven to be cost effective, faster and has resulted in consistently uniform, predictable fills1.
A study to compare the Nickel Titanium rotary and K-files on root canal preparation of freshly extracted 40 primary and permanent molars for their efficiency in preparation time, instrument failure and shaping the canals showed to be more advantageous in the child as the chair side time was reduced significantly. Irrespective of cost factors there were good results with nickel titanium in primary teeth.5
A study to compare the cleaning efficacy and time taken for instrumentation of deciduous molars using hand k-files and flex master rotary system by Nazari Moghaddam, Mehran M, Farajian Zadeh H concluded that there was no difference in cleaning efficacy at the apical and middle thirds, the coronal third was more effectively cleaned with hand files. Predictably time efficiency was a significant advantage with rotary system2.
Asimilar study conducted by Azar MR, Mokhtare M in cleaning ability of root canals between k-file and micromega rotary system in primary and permanent teeth in apical, middle and coronal third of canals showed there was no significant difference between primary and permanent teeth prepared with k-files and rotary instruments. In all the groups shorter times were recorded with rotary technique. The working time was shorter in primary than in permanent teeth6.
A study where India ink was injected into 160 mesiobuccal and distal root canals of mandibular primary molars was conducted. The 160 root canals were randomly divided into three experinmental groups and one control group. In each experimental group, either manual instruments [k-files] or rotary instruments i.e micromega or protaper were used to prepare root canals3. After cleaning the canals and clearing the teeth ink was evaluated with a stereomicroscope, Azar MR, Safi L, Nikaein A. concluded that manual K-files and micromega and protaper systems showed equally acceptable cleaning ability in primary molar root canals3.
A study to simplify endodontics using single file system namely waveone reciprocating system and one shape single file rotary system was conducted. Traditionally the shaping of root canals was achieved by the use of stainless steel hand files. However, techniques using stainless steel hand files have several drawbacks. Nickel titanium rotary shaping files fundamentally changed everything in endodontics as they focused on the concept of “Less is more”. Nickel Titanium rotary files made root canal therapy more accessible and delivered a ten times improvement. They provide optimal cutting efficiency along with better control of file breakage and thus increased patient safety and no risk for cross contamination. Dhingra A, Srivastava P, Chadda D, Banerjee S concluded that one shape and waveone are the new asset in endodontic instruments. Only one rotary file is there for endodontic treatment. A root canal treatment is approximately 4 times faster than a conventional treatment. Thus the overall duration of treatment is shortened4.
6.3 Objectives of the study
To evaluate the cleaning ability of micromega rotary system in preparing root canal in primary teeth.
To evaluate the cleaning ability of protaper rotary system in preparing root canal in primary teeth.
A. Extracted primary molars with at least two-thirds of intact root.
B. Teeth without internal or external root resorption and canal calcifications.
A .Teeth with internal and external resorption.
B. Teeth with canal calcifications.
Extracted primary teeth will be collected from Department of Pedodontics and Preventive dentistry Maratha Mandal Dental College Belgaum.
Among these teeth 40 primary molars extracted for therapeutic reasons with at least two-thirds of intact root and 7-12 mm length, will be cleaned in water and stored in 0.5% sodium hypochlorite for 24 hours. Coronal access will be with diamond straight fissure burs. Radiographs will be taken and 120 mesial and distal roots will be selected. After irrigation of the root canal with normal saline, a k-file with a compatible diameter will be introduced into the canal and the canal length will be determined at 1 mm from apex or root bevel. A k-file size#15 will be introduced into root canal and 1-2ml india ink will be injected with an insulin syringe into the orifice until the ink leaked from the foramen. The ink will be reapplied after diffusion and drying.
The roots will be randomly divided into 4 groups.
GROUP A [30 CANALS]-K-files will be used2.
GROUP B [30 CANALS]- Micromega system will be used.
GROUP C [30 CANALS]- Protaper system will be used.
GROUP D [30 CANALS]-Root canals will not be instrumented and considered as control group.
In groups A, B and C root canals will be prepared by the same operator. Normal saline will be used for irrigation. The teeth will be cleared for cleaning efficiency analysis i.e the teeth will be placed separately in jars with lid containing 5% formic and 5% nitric acid for 3 days. The acid will be renewed every 24hrs until the teeth are completely decalcified. The teeth will be washed under running water for 8hrs and dehydrated in 70%alcohol (for 16 hours changed every hour) 90% alcohol (for 3 hours changed every hour) and 96%alcohol (for 3 hours changed every hour). After dehydration teeth will be placed in methyl salicylate. At first the canals will be separated from CEJ and will be cut at 1mm above the working length (2mm upper than apex or root bevel) with a # 11 scalpel blade so that the apical section can be observed. Then the roots will be cut from the mid part of remaining canal. After clearing each tooth will be placed on a 1.5/2 inch red wax for easy observation. The removal of india ink from the cervical, middle and apical thirds will be analyzed with a stereomicroscope[Magnus –Indore, Madhya Pradesh ,India] with magnifications and scored as follows
A pedodontist and an oral pathologist who are blind to the groups will be asked for interpretation of the sections at the same time. The results will be tabulated and statistically analyzed with Kruskal-Wallis, Mann-Whitney U Test and one way ANOVA Test.
Statistical analysis- Data will be presented in tables and graphs.
The results will be statistically analyzed with:
Kruskal- Wallis Test
Mann- Whitney U Test
One way ANOVA 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.
7.4. Has ethical clearance been obtained from your institution in case of 7.3?
Barr ES,Kleier DJ,Barr NV. Use of nickel-titanium rotary files for root canal preparation in primary teeth. Pediatr Dent 2000;22:77-8.
Nazari Moghaddam K,Mehran M,Farajian Zadeh H. Root canal cleaning efficacy of rotary and hand files instrumentation in primary molars. Iran Endod J.2009;4:53-7.
Azar MR,Safi L,Nikaein A.Comparisonof thecleaningcapacityofM twoand Pro Taperrotarysystemsandmanual instrumentsinprimary teeth.Dent Res J.2012;9:146-51.
4) Dhingra A, Srivastava P, Chadda D, Banerjee S. Simplify your Endodontics with Single File System. IOSR-JDMS 2013;6:44-51
5) Nagaratna PJ, Shashikiran ND, Subbareddy VV. In vitro comparison of NiTi rotary instruments and stainless steel hand instruments in root canal preparations of primary and permanent molar. J Indian Soc Pedod Prev Dent. 2006;24:186-91.
6) Azar MR, Mokhtare M. Rotary Mtwo system versus manual K-file instruments: efficacy in preparing primary and permanent molar root canals. Indian J Dent Res. 2011:22(2):363.