Abstract
Background
Adequate canal preparation is essential in achieving successful outcome sequel to root canal treatment. Nickel-Titanium (NiTi) rotary instruments has steadily gained grounds in endodontics for root canals preparation, however, it is yet to be widely practiced among dental practitioners in Nigeria.
Aim and Objectives
To compare the treatment outcomes of single visit root canal treatment when either rotary or manual step-back preparation technique is used in shaping the canal, employing clinical and radiographic criteria.
Design of the study
A randomized controlled trial.
Setting
Conservation Unit of Restorative Dentistry Clinics, Lagos University Teaching Hospital (LUTH), Lagos, Nigeria.
Materials and Methods
120 consecutive consenting subjects were included in the study. The inclusion criteria were: medically fit individuals with restorable anterior, premolar or first molar tooth diagnosed with irreversible pulpitis, pulp necrosis or apical periodontitis; they had no to moderate pain, with periodontally sound and not excessively curved tooth. Randomization was performed by balloting using sealed envelopes and subjects were assigned in equal numbers to one of two groups, rotary and manual. Subjects were monitored following treatment for clinical and radiographic parameters at 1 day, 1 week, 1 month, 3 months and 6 months. Data analysis was done using SPSS-version 20.0, and differences were considered significant if p < 0.05.
Results
Twenty-seven (45%) and 23(38.3%) teeth in manual and rotary group respectively had pain at 1-day review. Significant difference in occurrence of pain in relation to both gender (p=0.001) and tooth-type (p=0.026) was noted between the groups at 1-day review. By the final review, there was no reported post-operative pain. There was no significant difference between the two groups in relation to the other clinical parameters at the different review periods. Twenty-four (40%) and 16 (26.7%) teeth had pre-existing periapical radiolucency in manual and rotary groups respectively; by final review, periapical radiolucency had reduced to 16.9% and 3.4% respectively, with the rotary group having significantly less radiolucency. Favourable outcome at 6-month review was significantly higher in the rotary group (96.6%), compared to the manual group (83.1%) in (p=0.033); the difference in outcome was due to significantly better outcomes with the molar tooth category in the rotary group.
Conclusion
There was a significantly more favourable treatment outcome in the rotary compared to the step-back technique in canal preparation, employing clinical and radiographic criteria.
Keywords: Rotary, Manual, Treatment-outcome, Single-visit, Endodontics, Instrumentation
Introduction
Canal preparation is the most significant step for a successful root canal treatment because this determines the extent of the sterility of the root canal system and the possibility of achieving a satisfactory three dimensional root filling.1,2 Traditional canal preparation techniques are often complex and their success largely dependent on the clinician’s skill.3 These preparation techniques have evolved over time and several advancements in the field of endodontics such as Nickel-Titanium (NiTi) rotary instrumentation, accurate apex locators, and digital radiography have assisted endodontists in performing root canal treatment (especially in molars) in a single visit.3–5 This makes patients more receptive to having endodontic treatment and is more productive for the clinician.5
Over the past few decades, NiTi rotary instruments have steadily gained grounds in endodontics; however, it is yet to gain popularity in developing countries. Several in vitro studies in literature have focussed on debris extrusion and quality of the prepared canals. These studies have consistently reported reduced apical extrusion of pulp debris and better shaping of canals with less procedural errors following the use of rotary files in canal preparation.3,6–10 Conflicting findings of clinical studies regarding post-operative pain exist - it has been reported that there is a significantly higher incidence of pain following manual preparation of the root canals compared to rotary preparation while another study has reported no significant difference.1,11–14 However, there is paucity of reports when comparing the success and treatment outcomes following these techniques. This randomized clinical trial was therefore conducted to compare the treatment outcomes of single-visit root canal treatment when either manual step-back or rotary preparation technique is used in shaping the canal, employing clinical and radiographic criteria.
PATIENTS AND METHODS
This randomized clinical study was carried out over an 18-month period from April, 2014 to September, 2015. Ethics approval was obtained from the Health Research and Ethics Committee of Lagos University Teaching Hospital (LUTH), Lagos, Nigeria with the protocol number- ADM/DCST/HREC/1684 The study was conducted at the Conservation Unit of Restorative Dentistry Clinics of the hospital. Procedures performed at the Conservative Unit of the Restorative Dentistry include endodontics, operative, fixed prosthodontic and implant procedures.
The clinical trial was also registered with the Pan African Clinical Registry (PACTR201804003323280). Following adequate explanation of the procedures and the research to each subject, a written informed consent was obtained from all the participants before commencing treatment.
Eligibility Criteria
The investigations were done following a detailed history and examination, by using an electric pulp tester- Digitest Pulp Vitality Tester (PARKELL INC. NY, USA) to determine the pulp status and periapical radiograph (using long cone paralleling technique) to assess extent of coronal radiolucency, size of periapical radiolucency if present, the root morphology and extent of canal curvature.
The inclusion and exclusion criteria were strictly observed when selecting the subjects. Consecutive subjects aged between 18 and 60 years who had an anterior, premolar or first molar tooth (maxillary or mandibular) with no pain or mild to moderate pain were included in the study after they consented. These subjects were diagnosed of irreversible pulpitis or apical periodontitis not exceeding 2x2mm periapical radiolucency or necrotic teeth with/without apical lesion associated with a non-discharging sinus. Patients having any tooth with severe pain were excluded to increase the objectivity when assessing the treatment outcome since they would need to be placed on strong analgesics before commencing treatment. Teeth with weeping canals, acute abscess, periodontally compromised teeth, excessively curved roots, unrestorable teeth, uncooperative patients and medically compromised patients (ASA Physical Status Classification III and beyond) were excluded from the study.
Sample selection
The subjects recruited for the study were consecutive patients that presented to the Restorative Dental Clinics at LUTH for root canal treatment who met the inclusion criteria and consented to participate in the study. A minimum sample size of 28 teeth per group was calculated by using the formula for comparing two independent proportions by Varkevisser et al15 and the prevalence value used for the calculation was based on a previous study by Wei et al (72.3% in the rotary group and 37.5% in the manual group with no pain).11 The α value was set at 5% and power of the study set at 80%.
Taking into consideration that teeth of all categories (single-rooted anterior teeth, multi-rooted premolar and molar teeth) were included in the study and in order to compensate for attrition and increase validity, the required sample size per group was increased to 60 teeth. One hundred and twenty teeth were randomly assigned into two groups of 60 teeth each (by picking out of 120 concealed envelopes, each containing a tagged slip). Subjects having multiple teeth that required treatment balloted separately for each tooth to be included in a particular group. The manual group had teeth whose root canals were prepared with stainless steel K-files (MANI, INC. Tochigi, Japan) using manual step-back preparation technique.1 The rotary group had teeth whose root canals were prepared using ProTaper NiTi rotary instrument (DENTSPLY MAILLEFER Ballaigues, Switzerland) in a crown-down preparation technique according to the manufacturer’s instructions.1
The Procedure
Single-visit root canal treatment performed on all the subjects was carried out by a single operator in order to eliminate inter-operator bias and standard laid down protocols were observed during treatment.1,16 The procedure performed was in accordance with the ethical standards of the committee on human experimentation (institutional and national) and with the last update of Helsinki Declaration, as revised in 2000. The standard protocol for treatment included local anaesthesia administration, rubber dam isolation, excavation of the carious lesion, and standard access cavity preparation. The working length for each canal was then estimated as the length when the file tip terminates 0.5mm short
of the radiographic apex (as determined by long cone paralleling technique). This was followed by biomechanical preparation of root canals (using either manual step-back technique with hand held K-files or ProTaper rotary files by subjection of the canals to a continuous rotary instrumentation in a crown-down manner) where the pulp chamber and canals were copiously irrigated with 2.5% sodium hypochlorite (RECKITT BENCKISER, Ogun, Nigeria) and lubricated with RC Prep (STONE PHARMACEUTICALS, Philadelphia, Pa, USA) during the entire course of canal preparation. This was followed by obturation of the canals by cold lateral compaction technique in the manual group (using Gutta percha ISO standardized 15-80 (GAPADENT CO., LTD Tianjin, China) and single cone technique in the rotary group (using matching ProTaper gutta percha) [DENTSPLY MAILLEFER Ballaigues, Switzerland]. The gutta percha were sealed onto the canal walls using Zical (ZOE) root canal sealant (PREVERST DenPro LTD. Jammu, India). Thereafter, a core build-up (with/without a post) and extracoronal restoration were used to replace lost dental tissue. All subjects that were selected for this study had root canal treatment successfully completed in a single visit. Prophylactic analgesics were not given to the patients following treatment but they were advised to use analgesics in the event of unbearable pain.
Review Period
Before the commencement of the study, the two review assessors were calibrated. Inter-examiner and intra-examiner reliability assessments were done and kappa values obtained were 0.82 and 0.85, respectively. The subjects were reviewed five times (at 1-day, 1-week, 1-month, 3-month and 6-month review) following the procedure. Several clinical (pain, swelling, mobility, tenderness to percussion, sinus tract and function of the treated tooth) and radiographic parameters (size of periapical radiolucency) were monitored during the review appointments. Pain was reviewed employing Universal Pain Assessment Tool-Faces Scale17 and patients’ use of analgesics. All the radiographs were assessed after mounting the films on an electronic radiographic viewer. An endodontic rule was used to measure the diameter of any periapical radiolucency.18 The tooth apex was monitored at each review to determine if radiolucency was absent or present. When radiolucency was present, it was assessed to determine if it was a new lesion appearing where there was none on initial presentation or if it was an existing lesion that had remained the same size, increased in size or decreased in size.
The treatment outcome was categorized using the clinical and radiographic criteria according to the guidelines set by the European Society of Endodontology.19 Treatment outcome was classified as favourable when there was absence of pain, swelling and other symptoms, no sinus tract, no loss of function and radiological evidence of a normal periodontal ligament space around the root. However, favourable outcome may be reversed when there is a re-infection. Uncertain outcome was defined as presence of radiographic evidence revealing a periapical lesion that has remained the same size or has only decreased in size. In such cases of unresolved periapical lesion, a further review is recommended until the lesion completely resolves or assessment can be continued for a minimum period of 4 years.19All the assessments were independently conducted by two experienced endodontists who were blinded to the study groups.
Statistical Analysis
Data analysis was done using Statistical Package for Social Sciences (SPSS) version 20.0 (IBM SPSS 20.0. IBM, Chicago, IL, USA) and the Kolmogorov-Smirnov test for normality analysed data distribution. Categorical variables were compared using Pearson’s Chi-square test, and numeric variables compared using independent student t-test. Differences were considered significant if p<0.05.
Flow chart showing how the study was designed
Results
Ninety-five subjects with a total of 120 teeth were treated and reviewed. There were 41 males and 54 females with an age range 18-60 years. There were no significant differences between the two groups with regards to age, sex ratios and tooth types. Pre-operative clinical and radiographic parameters of the two groups were not significantly different (Table 1).
Table 1. Socio-demographic characteristics and pre-operative findings of subjects.
| Variable | Treatment groups | Total N=120N (%) | ᵡ2 | p –value | ||
| Rotaryn=60 (%) | Manualn=60 (%) | |||||
| Gender | Male | 23 (38.3) | 30 (50.0) | 53 (44.2) | 1.842 | 0.084 |
| Female | 37 (61.7) | 30 (50.0) | 67 (55.8) | |||
| Age group (Years) | 11-20 | 5 (8.3) | 9 (15.0) | 14 (11.7) | 3.045 | 0.550 |
| 21-30 | 32 (53.3) | 24 (40.0) | 56 (46.7) | |||
| 31-40 | 12 (20.0) | 16 (26.7) | 28 (23.3) | |||
| 41-50 | 7 (11.7) | 6 (10.0) | 13 (10.8) | |||
| 51-60 | 4 (6.7) | 5 (8.3) | 9 (7.5) | |||
| 31.48±11.1 | 31.63±63 | 31.56±11.35 | ||||
| Tooth type | Maxillary anteriors | 19 (31.7) | 21 (35.0) | 40 (33.3) | 3.045 | 0.550 |
| Maxillary premolars | 15 (25.0) | 12 (10.0) | 27 (22.5) | |||
| Maxillary molars | 8 (13.3) | 6 (10.0) | 14 (11.7) | |||
| Mandibular anteriors | 11 (18.3) | 9 (15.0) | 20 (16.7) | |||
| Mandibular premolars | 0 (0.0) | 1 (1.7) | 1 (0.8) | |||
| Mandibular molars | 7 (11.7) | 11 (18.3) | 18 (15.0) | |||
| Pre-op clinical findings* | No signs and symptoms | 28 (46.7) | 27 (45.0) | 55 (45.8) | 0.321 | |
| Pain | 22 (36.7) | 32 (53.3) | 54 (45.0) | 0.053 | ||
| Grade I mobility | 7 (11.7) | 11 (18.3) | 18 (15.0) | 0.091 | ||
| Grade II mobility | 2 (3.3) | 1 (1.7) | 3 (2.5) | 0.515 | ||
| Tenderness to percussion | 28 (46.7) | 28 (46.7) | 56 (46.7) | 1.000 | ||
| Sinus tract | 3 (5.0) | 7 (11.7) | 10 (8.3) | 0.323 | ||
| Loss of function | 7 (11.7) | 11 (18.3) | 18 (15.0) | 0.091 | ||
| Pre-op radiographic findings | Normal features | 44 (73.3) | 36 (60.0) | 80 (66.7) | 2.400 | 0.121 |
| Periapical radiolucency | 16 (26.7) | 24 (40.0) | 40 (33.3) | |||
| Pre-op diagnosis | Irreversible pulpitis | 21 (35.0) | 17 (28.3) | 38 (31.7) | 1.763 | 0.881 |
| Apical Periodontitis | 29 (48.3) | 25 (41.7) | 54 (45.0) | |||
| Asymptomatic non-vital tooth with no apical lesion | 7 (11.7) | 11 (18.3) | 18 (15.0) | |||
| Asymptomatic tooth with apical lesion and sinus tract | 3 (5.0) | 7 (11.7) | 10 (8.3) | |||
| *Some teeth had multiple symptoms so the total here was more than 120 teeth | ||||||
One subject in each group did not complete the six months review period. The fallout subject in the rotary group did not show up for the final review whilst the subject in the manual group was referred for extraction following a fracture of the endodontically filled but uncrowned tooth which occurred in the second month following the endodontic treatment.
Twenty-seven (45%) teeth in manual group and 23 (38.3%) teeth in rotary group were painful at 1-day review; the difference was not statistically significant (χ2=0.55, p=0.46). Among the subjects that experienced pain at the 1-day review, 13 (21.7%) used analgesics in the manual group while 6 (10% ) took analgesics in the rotary group, however, this difference was not statistically significant (p=0.114). At subsequent reviews, a steady decline in the number of painful teeth was noted. Total resolution of pain was most pronounced at 1-week and 1-month review in both groups. By the 1-month review, only 2 (3.3%) of teeth in the manual group and 3 (5%) in rotary group were painful, the difference was not statistically significant (p=0.83). However, all these subjects could bear the pain and did not take analgesics. By the 3-month review, only one subject in the manual group still had mild pain which did not require analgesics while no subject had post-operative pain in the rotary group. By the final review, no case of pain occurred in the two groups. There was a significant difference between pain intensity pre-operatively and 1-week post-operatively (p = 0.002) in the manual group while a significant difference occurred between the pain intensity from the teeth pre-operatively and 1-day (p = 0.026) and 1-week (p = 0.009) post-operatively in the rotary group (Table 2)
Table 2. Comparison of incidence of pain, the use of analgesics and pain intensity in the treatment groups at pre-operative and 1-day/1-week post-operative review periods.
| Treatment Group | Variable | Pain group | Pre-operative periodn=60 (%) | 1-day post-operativen=60 (%) | p-value | 1-week post-operativen=60 (%) | p-value |
| Rotary | Pain Incidence | Pain | 22 (36.7) | 23 (38.3) | 0.850 | 15 (25.0) | 0.166 |
| No pain | 38 (63.3) | 37 (61.7) | 45 (75.0 | ||||
| Use of Analgesics | Pain | 12 (20.0) | 6 (10.0) | 0.125 | 2 (3.3) | 0.004 | |
| No pain | 48 (80.0) | 54 (90.0) | 58 (96.7) | ||||
| Pain Intensity | No pain | 38 (63.3) | 37 (61.7) | 0.026* | 45 (75.0) | 0.009 | |
| Mild | 9 (15.0) | 17 (28.3) | 13 (21.7) | ||||
| Moderate | 13 (21.7) | 4 (6.7) | 2 (3.3) | ||||
| Severe | 0 (0.0) | 2 (3.3) | 0 (0.0) | ||||
| Control | Pain Incidence | Pain | 32 (53.3) | 27 (45.0) | 0.361 | 12 (20.0) | 0.001 |
| No pain | 28 (46.7) | 33 (55.0) | 48 (80.0) | ||||
| Use of Analgesics | Pain | 11 (18.3) | 13 (21.7) | 0.917 | 2 (3.3) | 0.004 | |
| No pain | 49 (81.7) | 47 (78.3 | 58 (96.7) | ||||
| Pain Intensity | No pain | 28 (46.7) | 33 (55.0) | 0.415 | 48 (80.0) | 0.002 | |
| Mild | 21 (35.0) | 14 (23.3) | 10 (16.7) | ||||
| Moderate | 11 (18.3) | 12 (20.0) | 2 (3.3) | ||||
| Severe | 0 (0.0) | 1 (1.7) | 0 (0.0) | ||||
| n= Total number of treated teeth per group at the different review periods | |||||||
Gender was the only factor that had a significant association (p=0.001) in relation to pain in the manual group while tooth type was the sole factor in the rotary group that had a significant association (p=0.026) in relation to pain at 1-day review only (Table 3). There was no significant difference between the two treatment groups in relation to other clinical parameters (Table 4 and Table 5).
Table 3. Association between age, sex, tooth type and the incidence of pain in the treatment groups at 1-day post-operative review.
| Variables | Incidence of painin Rotary Group | Total n=60(%) | p-value | Incidence of painin Manual Group | Total n=60(%) | p-value | ||
| Pain n=23 (%) | No pain n=37 (%) | Painn=27 (%) | No painn=33 (%) | |||||
| Age group | ||||||||
| 11-20 | 2 (8.7) | 3 (8.1) | 5 (8.3) | 0.412 | 3 (11.1) | 6 (18.2) | 9 (15.0) | 0.942 |
| 21-30 | 15 (65.2) | 17 (45.9) | 32(53.3) 12 (20) | 11 (40.7) | 13 (39.4) | 24(40.0) | ||
| 31-40 | 3 (13.0) | 9 (24.3) | 7 (11.7) | 8 (29.6) | 8 (24.2) | 16(26.7) | ||
| 41-50 | 2 (8.7) | 5 (13.5) | 4 (6.7) | 3 (11.1) | 3 (9.1) | 6(10.0) | ||
| 51-60 | 1 (4.3) | 3 (8.1) | 5 (8.3) | 2 (7.4) | 3 (9.1) | 5 (8.3) | ||
| Gender | ||||||||
| Male | 7 (30.4) | 16 (43.2) | 23(38.3) | 0.430 | 6 (22.2) | 24 (72.7) | 30(50.0) | 0.001 |
| Female | 16 (69.6) | 21 (56.8) | 37(61.7) | 21 (77.8) | 9 (27.3) | 30(50.0) | ||
| Tooth type | ||||||||
| Max. anterior | 7 (30.4) | 12 (32.4) | 19(31.7) | 0.026 | 12 (44.4) | 9 (27.3) | 21(35.0) | 0.881 |
| Max. premolar | 6 (26.1) | 9 (24.3) | 15(25.0) | 1 (3.7) | 11 (33.3) | 12(10.0) | ||
| Max. molar | 6 (26.1) | 2 (5.4) | 8 (13.3) | 4 (14.8) | 2 (6.1) | 6 (10.0) | ||
| Mand. anterior | 1 (4.3) | 10 (27.0) | 11(18.3) | 5 (18.5) | 4 (12.1) | 9 (15.0) | ||
| Mand. premolar | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 1 (3.0) | 1 (1.7) | ||
| Mand.molar | 3 (13.0) | 4 (10.8) | 7 (11.7 | 5 (18.5) | 6 (18.2) | 11(18.3) | ||
Table 4. Incidence of clinical signs at post-operative review periods in the treatment groups.
| Variable | Review periods | Treatment groups | p-value | |||
| n | Rotary Group nA (%) | n | Manual Group nB (%) | |||
| Grade I mobility | 1 day | 60 | 7 (11.7) | 60 | 11 (18.3) | 0.395 |
| 1 week | 60 | 7 (11.7) | 60 | 11 (18.3) | 0.395 | |
| 1 month | 60 | 4 (6.7) | 60 | 8 (13.3) | 0.214 | |
| 3 months | 60 | 4 (6.7) | 59 | 5 (8.5) | 0.878 | |
| 6 months | 59 | 0 (0.0) | 59 | 1 (1.7) | 0.978 | |
| Grade II mobility | 1 day | 60 | 2 (3.3) | 60 | 1 (1.7) | 0.446 |
| 1 week | 60 | 2 (3.3) | 60 | 1 (1.7) | 0.446 | |
| 1 month | 60 | 0 (0.0) | 60 | 1 (1.7) | 0.978 | |
| 3 months | 60 | 0 (0.0) | 59 | 1 (1.7) | 0.978 | |
| 6 months | 59 | 0 (0.0) | 59 | 0 (0.0) | NA | |
| Tenderness to percussion | 1 day | 60 | 21 (35.0) | 60 | 19 (31.7) | 0.734 |
| 1 week | 60 | 21 (35.0) | 60 | 19 (31.7) | 0.734 | |
| 1 month | 60 | 9 (15.0) | 60 | 10 (16.7) | 0.891 | |
| 3 months | 60 | 2 (3.3) | 59 | 0 (0.0) | 0.473 | |
| 6 months | 59 | 1 (1.7) | 59 | 0 (0.0) | 0.978 | |
| Sinus Tract | 1 day | 60 | 3 (5.0) | 60 | 7 (11.7) | 0.391 |
| 1 week | 60 | 3 (5.0) | 60 | 7 (11.7) | 0.391 | |
| 1 month | 60 | 2 (3.3) | 60 | 5 (8.3) | 0.654 | |
| 3 months | 60 | 0 (0.0) | 59 | 0 (0.0) | NA | |
| 6 months | 59 | 0 (0.0) | 59 | 0 (0.0) | NA | |
| Loss of function | 1 day | 60 | 7 (11.7) | 60 | 9 (15.0) | 0.234 |
| 1 week | 60 | 6 (10.0) | 60 | 5 (8.3) | 0.914 | |
| 1 month | 60 | 2 (3.3) | 60 | 2 (3.3) | 1.000 | |
| 3 months | 60 | 0 (0.0) | 59 | 0 (0.0) | N/A | |
| 6 months | 59 | 0 (0.0) | 59 | 0 (0.0) | N/A | |
Table 5. Distribution of incidence of swelling and periapical radiolucency versus the diagnosis in the treatment groups at the post-operative review periods.
| Review period | Rotary Group | Manual Group | ||||
| Pulp diseases (n=28) | Periapical diseases (n=32)* | Pulp diseases (n=22) | Periapical diseases(n=38)* | p-value | ||
| Presence of swelling | ||||||
| Day 1 | Absent | 28 (100.0) | 31 (96.9) | 22 (100.0) | 34 (89.5) | 0.171 |
| Present | 0 (0.0) | 1 (3.1) | 0 (0.0) | 4 (10.5) | ||
| Week 1 | Absent | 28 (100.0) | 31 (96.9) | 22 (100.0) | 38(100.0) | 0.315 |
| Same size | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | ||
| Decreasing | 0 (0.0) | 1 (3.1) | 0 (0.0) | 0 (0.0) | ||
| Increasing | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | ||
| 1 Month | Absent | 28 (100.0) | 31 (96.9) | 22 (100.0) | 38(100.0) | |
| Same size | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | ||
| Decreasing | 0 (0.0) | 1 (3.1) | 0 (0.0) | 0 (0.0) | ||
| Increasing | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | ||
| 3 Months | Absent | 28 (100.0) | 32 (100.0) | 22 (100.0) | 37(100.0) | 1.000 |
| 6 Months | Absent | 28 (100.0) | 32 (100.0) | 22 (100.0) | 37(100.0) | 1.000 |
| Presence of radiolucency | ||||||
| Day 1 | Absent | 28 (100.0) | 16 (50.0) | 22 (100.0) | 14 (36.8) | 0.121 |
| Present | 0 (0.0) | 16 (50.0) | 0 (0.0) | 24 (63.2) | ||
| Week 1 | Absent | 28 (100.0) | 16 (50.0) | 22 (100.0) | 14 (36.8) | 0.196 |
| Same size | 0 (0.0) | 16 (50.0) | 0 (0.0) | 24 (63.2) | ||
| 1 Month | Absent | 28 (100.0) | 16 (50.0) | 22 (100.0) | 16 (42.1) | 0.098 |
| Same size | 0 (0.0) | 9(28.1) | 0 (0.0) | 15 (39.5) | ||
| Decreasing | 0 (0.0) | 7(21.9) | 0 (0.0) | 7 (18.4) | ||
| 3 Months | Absent | 28 (100.0) | 22(68.8) | 22 (100.0) | 16 (43.2) | 0.453 |
| Same saize | 0 (0.0) | 2(6.3) | 0 (0.0) | 8 (21.6) | ||
| Decreasing | 0 (0.0) | 8(25.0) | 0 (0.0) | 13 (35.1) | ||
| 6 Months | Absent | 28 (100.0) | 29(93.5) | 22 (100.0) | 27 (73.0) | 0.194 |
| Decreasing | 0 (0.0) | 2(6.5) | 0 (0.0) | 10 (27.0) | ||
Twenty-four (40%) teeth in manual group and 16 (26.7%) teeth in rotary group had pre-existing periapical radiolucency. A decrease in size of radiolucency was noticed in some teeth that presented with periapical lesion by the 1-month review. There was no new incidence of periapical radiolucency among the treated teeth and no existing periapical radiolucency remained the same size or increased in size at the different review periods (Table 5). There was no significant difference when comparing diagnosis and presence of periapical radiolucency between the two treatment groups (Table 5). However, the total number of teeth with radiolucency still present was significantly higher in the manual group at 3-month (p = 0.04) and 6-month (p = 0.023) review periods compared to the rotary group. At final review, up to 16.9% in the manual group still had radiolucency present compared to 3.4% in the rotary group.
One anterior and one molar teeth in the rotary group had uncertain outcome at the 6-month period, whilst in the manual group 10 teeth had uncertain outcome and majority of them (7 teeth) were molar teeth. Favourable outcome/success rate at 6-month review was significantly higher in the rotary group, 57 (96.6%) compared to manual group 49 (83.1%) (p=0.033). The difference in outcomes was due to better outcomes with the molar tooth category in the rotary group (p = 0.039). (Table 6).
Table 6. Distribution of treatment outcome versus the tooth categories in the treatment groups at the final review.
| Variables | Treatment outcomein Rotary Group | Total in the Rotary Groupn=59 | Treatment outcome in Manual Group | Total in the Manual Group n=59 | p-value | ||
| Favourable n=57 | Uncertain n=2 | Favourable n=49 | Uncertainn=10 | ||||
| Tooth type | |||||||
| Anterior teeth | 29 (96.7%) | 1 (3.3%) | 30(100.0%) | 29 (96.7%) | 1 (3.4%) | 30(100.0%) | 0.957 |
| Premolars | 14(100.0%) | 0 (0.0) | 14(100.0%) | 11 (84.6%) | 2 (15.4%) | 13(100.0%) | 0.348 |
| Molars | 14 (93.3%) | 1 (6.7%) | 15(100.0%) | 9 (56.3%) | 7 (43.7%) | 16(100.0%) | 0.039 |
Discussion
Health care professionals are often resistant to change conventional modes of treatment and adopt new approaches introduced in practice20 They are often unwilling to leave predictable treatment procedures because they fear the adoption of some new modalities may not yield a successful outcome.21
For a root canal treatment to be regarded as successful, both the clinical and radiographic outcomes must be favourable. This is characterized clinically by the absence of symptoms and clinical signs (when the tooth is asymptomatic, and there is firmness of teeth in the socket and without any signs of inflammation or infection) and radiographically with evidence of a satisfactory healing of periapical lesion or by a total resolution within six months and no occurrence of pathologic root resorption.22
All root canal preparation techniques have been associated with some degree of debris extrusion into the periapical tissues. Some researchers inferred that the less extrusion following rotary instrumentation is associated with a better outcome.9,23 Implicit data comparing treatment outcome can only be deduced from clinical and radiographic parameters,24,25 however, there is a dearth of these clinical studies in literature.
Post-operative pain
The results showed that after 24 hours following root canal treatment, 21.7% of subjects in the manual group used analgesics while 10% took analgesics in the rotary group. This is most likely due to the fact that rotary technique is associated with less apical extrusion compared to manual step-back technique.9,23 This study also revealed that total resolution of pain was most pronounced at 1-week and 1-month review in both groups.
Ahmed et al1 in 2012 reported a low incidence rate (13.3% in the rotary group and 15.7% in the manual group) of post-operative pain after a 48-hour review compared to the findings of this present study that reported a much higher incidence rate of post-operative pain (38.3% in the rotary group and 45% in the manual group) at 24 hours review and after an even longer review period of 1 week (25% in the rotary group and 20% in manual group). This may be due to the fact that their study included only anterior teeth with irreversible pulpitis/apical periodontitis whereas our study included both anterior and posterior teeth with a wider array of pathologic conditions. The varying report could also be attributed to the amount of extrusion which would vary between different operators. It could also be due to the pain threshold and intensity that would have differed from one patient to another. However, the difference in pain incidence between the two groups in their study was not statistically significant which is in agreement with this study. This report of no significant difference when comparing pain incidence following the use of rotary and hand instrumentation is also in agreement with findings made by Aqrabawi and Jamani in 200614
Kashefinejad et al in 201626 in a similar study, reported that the use of rotary instruments for canal preparation resulted in a significantly lower incidence of post-operative pain compared to hand instrumentation 24 hours after single-visit root canal treatment. This was contrary to the findings of this present study. The varying reports can be attributed to the difference between the two study protocols. In their study, acute apical periodontitis and non-vital teeth were excluded unlike this present study which included these diagnoses.
Vieyra and Guardado (2009) also reported a significantly lower incidence of post-operative pain following rotary instrumentation compared with manual preparation of the canals.13 At 24 hours review of their study, 93.3% of patients in the rotary group and 71.7% in the manual group experienced none to slight pain. By the final review for pain (at 72 hours) in their study, there was no incidence of pain in the rotary group but a further increase in incidence of moderate pain was noted in manual group. This pattern of pain incidence was different compared to the findings of this present study. The significant difference reported in their study might be due to the use of a less objective pain scale rating - patients with no pain and slight pain being grouped together. Also, pain was assessed by telephone interview which made the response from their subjects more subjective. In this present study, pain was rated during the review/appointment visits. Only non-vital teeth underwent root canal treatment in their study unlike this present study where teeth with either vital or non-vital status were included. A different rotary system was used in their study and two different operators treated the subjects unlike this present study in which all subjects were treated by a single operator. This would have probably resulted in different amount of apical extrusion of canal contents leading to varying incidence of pain.8–10,23,27
Arias et al also revealed that a significantly greater proportion of patients in their manual group reported pain compared to patients in the rotary group following single-visit root canal treatment28 They also noted a significantly longer pain duration in the rotary group compared to the manual group (p = 0.008). This was contrary to the findings in this present study. The duration of pain post-operatively could be due to the difference in amount of debris extrusion at the end of each endodontic procedure which would vary from one operator to another and one rotary system to the other.
The study also revealed that factors which affect level of post-operative pain are gender for manual technique and tooth type for rotary technique. The significantly higher number of females that experienced pain in the manual group agrees with the reports of other researchers.29,30 Several hypotheses have been proffered but a legitimate explanation is based on report of the biological differences between genders.29 The significant difference of pain in relation to tooth type in the rotary group is in agreement with findings of other studies.29–31 This might be due to the fact that operators have challenges in treating posterior teeth due to poor access, multiple roots, complex anatomy and an increased possibility of missing an additional canal that might be present.32
Tenderness to Percussion and Swelling
A much lower incidence of tenderness to percussion (1.6% and 5% in the rotary and manual group respectively) at 1-week was reported in a study conducted in 2009 by Vieyra and Guardado13 compared to the findings of this present study (35% and 31.7% in the rotary and manual group respectively). The high incidence in our study could be attributed to the fact that majority of subjects in both groups had apical periodontitis. A tooth with a periapical lesion would be tender because of the infection and/or inflammation at the periapical region which may take time to resolve. However, following an endodontic procedure of a necrotic tooth, if there is no extrusion of infected pulp remnant or irrigant into the periapical region, there will be no apical tissue reaction to cause tenderness of tooth to percussion (hence, a lower percentage of tenderness to percussion).
A study conducted by Pamboo et al33 in 2014 revealed that the incidence of post-operative swelling at 1-week review was significantly lower after using rotary instrumentation (0.9%) compared to canal preparation following the use of hand files (3.03%). This is contrary to the findings of this present study where there was no significant difference in incidence of swelling when comparing the two techniques at that same time period. The different findings of the two studies can also be attributed to the fact that treatment was performed in either single/multiple visits in their study unlike our study where all the patients had treatment completed in a single visit. In addition, some patients were placed on antibiotics and/or analgesics after treatment in their study unlike this study where no subject used any of these medications prophylactically post-treatment. These varying reports of swelling incidence are possibly due to the differences that may have arisen from the different treatment protocols such as number of operators, dexterity of operators, number of endodontic visits and the use of medication pre- and post-treatment.
Periapical radiolucency
The manual group had a higher percentage of teeth with associated pre-operative periapical radiolucency, 40%, compared to 26.7% for the rotary group. There was progressive healing of these lesions in both groups with an evident decrease in size of lesion. At the 6-month review, the number of teeth that still had radiolucency was significantly higher in the manual group, 16.9% compared to 3.4% in the rotary group. This significant difference at final review can be attributed to more pre-operative cases with periapical radiolucency in the manual group compared to the rotary group. Conversely, better periapical healing in the rotary group supports the claim that rotary endodontics is associated with less extrusion of irritants into the periapical tissue.
Summary of Treatment Outcome
There are no universally accepted criteria for assessing treatment success. The treatment outcome criteria used in this study was defined by the European Society of Endodontology which categorized outcome as favourable, uncertain or unfavourable.19 Success of endodontic treatment depends largely on long-term results. The occurrence of post-operative pain shortly after treatment can still result in long-term success and vice versa.34 Liu and Liao35 support the view that teeth with pre-existing periapical radiolucency have about 4 times higher likelihood of failure following treatment and about 3 times likelihood of unsatisfactory clinical outcome when compared to those without periapical lesions.
At the final review of our study, 83.1% subjects in the manual group had significantly lower favourable outcome/success compared to the rotary group, 96.6%. Liu and Liao (2008) reported that rotary instrumentation was associated with a higher chance of endodontic success compared to hand instrumentation.35 They reported in their study that the successful endodontic outcome rate was 77.3% in the rotary group and 60% successful endodontic outcome in the manual group. However, the reason for the lower outcome when compared to this present study can be attributed to differences in inclusion/exclusion criteria. In their study, only subjects with affected 1st and 2nd molars were included whereas anterior teeth, premolars and 1st molars were included in this present study. The success rate is usually lower in molars compared to other teeth because of their complex anatomy and poorer accessibility.30,35
Furthermore, Liu and Liao (2008) recognized that clinical experience is a key factor that affects the overall treatment outcome.35 They reported lower endodontic outcomes in both groups. Their study revealed that more undergraduates than postgraduates performed the procedure which led to reduced success rate of 63.1% in endodontic treatment carried out by undergraduates compared to 81.5% when performed by postgraduates. Although their study was also conducted in a teaching hospital, several operators with varying expertise treated the subjects unlike this present study where all subjects were treated by a single postgraduate endodontist.
Farzaneh et al in 2004 used the criteria: ‘healed’ and ‘diseased’ to categorize the treatment outcome in their study.36 They reported a significant difference in the healed rate in relation to rotary compared to step-back technique. They surmised that techniques are the main determinants for treatment outcomes. The findings of our study are in agreement with the findings of their study.
Fleming et al (2010) in a retrospective study comparing the endodontic treatment success between the step-back techniques and rotary technique revealed that no statistical difference was noted between the two groups in terms of survival rate37 Root canal treatment performed on subjects in their study was mostly completed after multiple visits in the group using hand instrumentation to prepare the canals unlike single visit treatment in the rotary group. This is different from treatment performed in both groups of this study where treatment was completed in a single visit by a single operator. The findings of this study were also different from this present study because the criteria they used to categorize treatment outcomes were different from this study.
Conclusions
In conclusion, when all clinical and radiographic findings of all teeth were taken into consideration after a 6-month review, there was a significant difference (p = 0.033) in the treatment outcomes between manual step-back technique and rotary technique employed for canal preparation in single visit root canal treatment. There also was a significant difference (p=0.039) noted when comparing the treatment outcome in multi-rooted molar teeth. Continued monitoring of the subjects up to 4 years following treatment should be conducted as recommended by the European Society of Endodontology19 to further ascertain the success rate in these two treatment groups.
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