Comparison of Endodontic Treatment Outcome with Protaper and K3 Rotary Systems

Comparison of Endodontic Treatment Outcome with Protaper and K3 Rotary Systems
Nabeel Ahmed1, Rizwan Jouhar2, Ismail Sheikh3, Narendar Dawani4

1. Assistant Professor, Department of Operative Dentistry, Altamash Institute of Dental Medicine, Karachi.
2. Assistant Professor, Department of Operative Dentistry, Altamash Institute of Dental Medicine, Karachi.
3. Professor & HOD, Department of Operative Dentistry, Altamash Institute of Dental Medicine, Karachi
4. Assistant Professor, Dept of Community Dentistry, Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Sciences, Karachi.
Correspondance :“Dr. Narendar Dawani”

How to CITE:

Ahmed N, Jouhar R, Sheikh I, Dawani N. Comparison of endodontic treatment outcome with protaper & k3 rotary systems. J Pak Dent Assoc 2013; 22(3): 206-211.


Instrumentation is a key part of root canal therapy which allows disinfection, placement of medication and filling of the root canal system. Over the years several instruments have been developed for root canal. The aim of this study was to compare the outcome of endodontic treatment performed with Protaper and K3 rotary systems.


A Randomized control trial was performed at the Operative dentistry department of Altamash Institute of Dental Medicine, Karachi. A total of 249 patients were selected from the outpatient department and were randomly allocated to two treatment groups using random allocation table. After obtaining written consent, root canal treatment in group 1 was performed with Protaper rotary instruments; whereas, in group 2, treatment was performed with K3 rotary instruments. Outcome of the treatment (success or failure) was evaluated after 6-months by using Periapical Index (PAI).


Fourteen out of 249 patients did not attend the follow up so they were excluded from the final analysis. Out of 235 patients, treatment outcome of 198 (84.3%) patients was successful. In Protaper rotary group, 97 (82.2%) patients had successful treatment outcome while in K3 group, 101 (86.3%) patients showed successful outcome. On the basis of PAI score, no statistically significant difference in the treatment outcome was observed between the two rotary groups.


No significant difference in the outcome of endodontic treatment performed with either Protaper or K3 rotary systems was noticed.


Rotary systems, Protaper, K3, Periapical index, treatment outcome


Effective cleaning and shaping of the root canal system is essential for successful endodontic treatment. Root canals should be shaped in a manner that should facilitate proper irrigation, placement of medication and three dimensional obturation of the root canal system . Instrumentation alone of the necrotic root canals has been shown to reduce the counts of intra-canal bacteria significantly. However, irrigation remains an indispensible adjunct in order to achieve the goal of elimination of infection.

In recent years several new rotary systems have been introduced, Protaper and K3 are one of them. The Protaper rotary system represents the new generation of instruments for shaping root canals. This system consists of three shaping files and five finishing files. A unique feature of Protaper system is each instrument has changing tapers over the length of its cutting blades. Other highlighted features are: convex triangular cross-section which enhances cutting action by decreasing friction between dentine and file blades, a non-cutting modified guiding tip which allows each instrument to safely follow the root canal and changing pitch as well as helical angle which prevents the instruments from screwing into the canal.

While, the K3 rotary system was introduced in 2002 and since then has been widely accepted by the endodontic community. This system consists of .02, .04, .06, .08, .10 & .12 tapered instruments; however the taper remains constant throughout the length of the blade. These files are designed to have wide radial land which makes the instrument more resistant to torsional and rotary stresses. It also features a radial land relief which prevent over engagement of file during instrumentation thereby preventing instrument separation. Additional features include a positive rake angle, safe ended tip, variable core diameter to increase flexibility of instrument and variable helical angle for better cutting efficiency.

Peters et al. evaluated Protaper root canal preparation by Micro Computed Tomography (micro CT) and concluded that Protaper rotary system prepared the canals without any major procedural errors also reported that Protaper files generate lower torque scores and furthermore, high forces that are generated in cases of constricted canals were insufficient to fracture Protaper instruments. Schaffer and Florek and Di Fiore et al reported accomplishment of original canal curvature without any major change and fracture incidence of only 0.41%.Bergmans et al. compared the canal preparation of Protaper and K3 rotary systems and concluded that a good centered apical preparation is achieved with Protaper system compared to the K3; however Protaper instruments have a tendency of transportation towards the furcation in the coronal region.

Over the years several in vitro studies have analyzed the performance of these rotary systems but limited information is available regarding the outcome of endodontic treatment performed with these instruments. Moreover, so far no in vivo study has been conducted locally which has evaluated the outcome of endodontic treatment performed with Protaper and K3 systems. Therefore, it would be beneficial to conduct an in vivo study that will compare the outcome of endodontic treatment performed with these rotary systems and determine which treatment modality has a better success rate so that the same will be used in such cases.


A randomized control trial was conducted in Department of Operative Dentistry at Altamash Institute of Dental Medicine (AIDM) for duration of Six months after ethical approval from Head of the Department as an ethical committee does not exist in the institute. World Health Organization’s (WHO) sample size calculator program “STEPS” was used to determine the sample size of study group with expected success rate of Protaper & K3 systems 77% & 67% (Cheung and Liu, 2009)respectively i.e.

P1=77% & P2= 67%, and 95% Confidence Interval. Hence, total sample (N) was calculated to be 249. Simple- Random sampling was employed to assort participants in the two treatment groups; one treated through Protaper rotary system and one by K3 system. Individuals aged between 15-60 years having single rooted teeth with pulp necrosis or chronic apical periodontitis and a pre-operative PAI score between 3 and 5(evaluated through radiograph)who gave written consent for participation were included for the control trial. On the other hand, non- restorable teeth, vertical root fractures, teeth with immature apices, teeth with a draining sinus and mal- positioned teeth were not considered for the study. The data was personally collected on a Proforma by the principal investigator.

A criterion for successful case was set at PAI score 1 and 2 based on radiographic assessment on follow-up while cases in which radiolucency was not present pre- operatively then there should not be any radiolucent area on the follow-up examination as well. Whereas, failed cases were those which did not show a decrease in the size of periapical radiolucent area on follow up examination. This category also includes those cases which show an increase in size of the lesion or develop radiolucency post-operatively (Friedman, 2002).

PAI score isa scoring system for radiographic assessment of Apical Periodontitis (Orstavik et al, 1986).

It is as follows:
PAI 1: Normal apical periodontium.
PAI 2: Bone structural changes indicating, but not pathognomonic of Apical Periodontitis.
PAI 3: Bone structural changes with some mineral loss characteristic of Apical Periodontitis.
PAI 4:Well defined radiolucency.
PAI 5: Well defined radiolucency with radiating expansion of bone structural changes.

All endodontic treatment procedures were carried out by the principal investigator. A written consent was taken from the patient before the commencement of endodontic treatment. Patient’s preoperative periapical radiograph were thoroughly evaluated and a PAI score was assigned between 3 & 5 followed by random allocation of the patient to one of the two treatment groups using random allocation table. All endodontic treatments were carried out in a single visit and dental loupes were used for magnification. Local anesthesia was administered followed by rubber dam application for isolation. Straight line access was gained and coronal flaring of root canals was carried out with Gates Glidden (GG) burs in a crown-down manner. An ISO standardized #10K or a #15 K file was inserted to the estimated working length and a periapical radiograph exposed to establish final working length. After establishing a glide path with #15 K file the shaping of root canal system was carried out with Protaper rotary system in group 1 whereas, K3 rotary system was used to shape root canals in group 2. Both rotary systems were used according to manufacturer’s guidelines, 2.25% Sodium Hypochlorite was used as an irrigant and Glyde (Dentsply Maillefer, Ballaigues, Switzerland) as a lubricant. After completion of cleaning and shaping, root canals in both groups were obturated with Gutta-Percha and AH plus sealer (Dentsply Maillefer, Ballaigues, Switzerland) using cold lateral compaction technique. A postoperative radiograph was exposed, access cavity was sealed with composite resin and patient was re-called after six months for follow-up. On follow-up visit, a periapical radiograph was exposed and evaluated for change in PAI score. Cases with PAI score 1 & 2 on follow up visit were considered as successful.

The data was entered and analyzed with statistical package for social science (SPSS 17). Descriptive statistics was used for study variables while Chi square test was applied to compare success rate between groups for outcomes and independent sample t-test was applied to compare mean difference between groups for age. Stratification technique was used to control effect modifiers like age, gender, and PAI scores to observe effect on outcome. P<0.05 was considered as level of significance.


Out of total 249 patients included in the study, 14 patients were unable to follow up so they were excluded from the study. Hence, total 235 patients were included in the final analysis. One-hundred & eighteen patients were treated with Protaper system and 117 with K3 rotary system.

The mean age of patients was 36.54 ±13.10 years (95% C I: 34.86 to 38.22). Out of 235 patients, 11.5% (27) were ≤ 20 years, 28.5% (67) were 21 to 30 years old, 18.7% (44) were 31 to 40 years old, 21.3% (50) were 41 to 50 years and 20.0%(47) were aged 51 to 60 years. Total 47.7% (112) were female and 52.30% (123) were male patients. Amongst Protaper rotary system group,48.3% were females and 51.7% (61) were males whereas in K3 rotary system group, 47.0% (55) were females and 53.0% (62) were males.

Out of total 235 patients, successful treatment outcome was observed in 198 (84.3%) patients and 15.7% (37) patients showed treatment failure. Among 118 patients of Protaper rotary system group, 17.8% (21) patients had treatment failure while 82.2% (97) patients had success. As for K3 system, 101 (86.3%) patients showed successful treatment results and 13.7% (16) suffered failure. However, no significant difference (Chi-square= 0.752, p=0.386) was observed between the two treatment groups as shown in Table I.

Out of 235 patients, outcome of patients belonging to different age categories was as follows: 81.5% (22) patients of ≤ 20 years age, 80.6% (54) patients of 21 to 30 years, 81.8% (36)patients of 31 to 40 years, 86.0% (43) patients of 41 to 50 years, and 91.5% (43) patients of 51 to 60 years age groups had successful treatment results whereas and 18.5% (5) patients of ≤ 20 years, 19.4% (13) patients of 21 to 30 years, 18.2% (8) patients of 31 to 40 years, 14.0% (7) patients of 41 to 50 years, and 8.5% (4) patients of 51 to 60 years age groups suffered failure. No significant difference was observed between treatment groups with respect to age stratification except age category of 41 to 50 years as shown in Table II.

Among 112 female patients, treatment outcome of 81.3% (91) females was successful and of 18.8% (21) females had failure whereas out of 123 male patients, 87.0% (107) patients had successful treatment outcome while 13.0% (16) males suffered failure. Significant difference was not observed between the treatment groups with respect to gender as shown in Table III.

In respect to Periapical Index (PAI) score criteria, out of 105 patients who had a PAI score of 3 pre-operatively; 95.2% (100) patients progressed towards successful post- operative outcome. Among 101 patients with pre-operative PAI score of 4; 84.2% (85) individuals had post-operative success, whilst out of 29 patients having PAI score of 5, post-operative successful outcome was observed in 44.8% (13) of them. No significant difference was observed between groups with respect to Periapical Index (PAI) scores as shown in Table IV.


The overall success rate of root canal treatment irrespective of the rotary system employed was 84.3% (see Table I) which is high in comparison to a study by Cheung and Liu which reported an overall success rate of 77% when they evaluated the outcome of endodontic treatment performed with NiTi rotary instruments whereas the success rate with hand files was observed tobe 60%.On the other hand, Peters and colleagues (Peters etal, 2004) reported a success rate of 86.7% when they evaluated the outcome of endodontic treatment performed with three different NiTi rotary systems. These findings indicate that rotary systems are far more effective and produce successful outcomes compared to hand files.

The K3 rotary system had slightly higher successful outcome compared to Protaper system however, the difference was insignificant. The plausible explanation might be due to the fact that the K3 treatment group had comparatively higher number of cases with a PAI score of 3 than the Protaper treatment group (see Table IV).

Age and gender of individuals had no influence on either of the two treatment groups probably due to the reason that success or failure of root canal treatment depends on the condition of local apical tissues and adjoining areas rather than the socio-demography of affected individuals (see Table II & III).

The primary aim of endodontic treatment is to heal the inflammation of periapical tissues . Therefore to evaluate the periapical changes, PAI scoring system as described by Orstavik was utilized. Earlier studies have also used the PAI scoring system to evaluate the outcome of endodontic treatment and it has shown to be a good measure for assessing healing of the apical lesions followed by endodontic therapy. Moreover, PAI scoring system has shown good inter-examiner and intra-examiner reliability as well. Patients with pre-operative PAI score 3 showed highest success rate (95.2%) followed by patients with pre-operative PAI score 4 (84.2%) and pre-operative PAI score 5 (44%). However, the difference was insignificant. The plausible explanation (Table IV) is that in the current study, patients were re-called after 6 months to evaluate healing in the periapical status of endodontically treated teeth. It can be argued that this re-call time might be short as it may not allow significant improvement in the PAI score and if the patients were to be kept on follow-up for a longer time period, there might a possibility to find significant apical healing and reduction in PAI score of endodontically treated teeth. However, some studies have also shown that a 6-month re-call time is sufficient to demonstrate changes in the PAI score.

In this study a very strict criteria to evaluate the outcome of endodontic treatment was applied. A case to be characterized as successful had to have a PAI score of 1 or 2 on follow-up examination. Moreover, all teeth that were selected in this study had chronic apical periodontitis lesion which itself is a poor prognostic factor for endodontic treatment. Despite these factors, a high percentage of endodontic treatments were successful and if these patients are kept on follow-up and re-called after a longer interval to assess their PAI scores, there is possibility that a higher success rate compared to what has been achieved at present is possible.

This study has highlighted that root canal treatment performed with either Protaper or K3 rotary systems has a high chance of a success outcome. However, the matter of fact is that minimal information is available in literature with regard to treatment outcomes of rotary instruments particularly Protaper and K3. Therefore, current research would provide a pedestal for studies ahead.


The study findings conclude that there is no significant difference in the outcome of endodontic treatment performed with Protaper and K3 rotary systems. Additionally, no significant difference in treatment outcome was observed between the two study groups with respect to age, gender and PAI score.
Competing interests: The authors declare that they do not have any competing interests.
Financial Support/Funding: No financial support/funding was received for this study.
Acknowledgments: Immense appreciation goes to the patients for their involvement and cooperation in this research.

Authors’ contributions: Ahmed N conceived the study, collected and diagnosed the study findings and finally wrote manuscript. Jouhar R assisted in collecting data, diagnosing study findings, and editing manuscript. Dawani N managed the literature search, analysis of data, and writing and finalizing the manuscript. Sheikh I supervised the project in addition to editing and help in writing manuscript.


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