Comparative Evaluation of the Effectiveness of Rotary Instrumentation over Manual Instrumentation with Ultrasonic Irrigation on Incidence, Duration, and Intensity of Postendodontic Pain: An In vivo Study.

AIM: The aim of this study was to compare the effectiveness of rotary instrumentation over manual instrumentation with ultrasonic irrigation on incidence, duration, and intensity of postendodontic pain (PEP). SUBJECTS AND METHODS: Eighty patients, with asymptomatic irreversible pulpitis in maxillary anterior teeth, were selected and treated with single-visit endodontic treatment. Patients were randomly divided into 2 groups (40 each), Group A (K files using step-back technique) and Group B (ProTaper Next using crown-down technique) along with passive ultrasonic irrigation. Patients were recalled, examined, and asked to fill up questionnaire after 24 h, 48 h, and 7 days. On the basis of response given in the feedback forms, incidence, duration, and intensity of PEP were evaluated.
RESULTS: Statistical analysis of the data was carried out using Chi-square test, and level of significance (P < 0.05) was evaluated. More incidence of pain was noticed in Group A when compared with Group B. Significant difference found between two groups (χ 2 = 22.759; P = 0.001). There was also statistically significant difference between two groups at different time intervals.
CONCLUSION: Both instrumentation techniques under investigation cause PEP. The incidence of pain was more in manual technique than rotary technique. The duration of pain was higher in manual group than rotary group at different time intervals. Copyright:

INTRODUCTION

Postendodontic pain (PEP) is one of the principal issues in endodontic treatment. Although the success of endodontic treatment is highly related to the removal or reduction of PEP, many clinical studies have reported varying degrees of pain, ranging from 25% to 40%.[1] Many contributing factors are responsible for PEP such as improper cleaning and shaping of the canals, missed canals, and improper obturation, of these, the major factor responsible for pain is the extrusion of debris into the apical region that basically depends on the technique of canal preparation. It has been stated that the apical extrusion of contaminated debris during the chemomechanical instrumentation of root canals may exacerbate the inflammatory response and may induce periapical inflammation.[2] All instrumentation techniques have been reported to be associated with extrusion of infected debris, even when preparation is maintained short of the apical terminus. Among all the manual techniques, it has been shown that stainless steel files, K-files, extrude more amount of debris apically.[34] Ruiz-Hubard et al. found that less debris was apically extruded using the crown-down pressureless technique in curved and straight canals when compared with step-back instrumentation.[5]

Studies by Townsend and Maki in 2009 and Lee et al. in 2004 have shown that ultrasonic agitation was more efficacious than needle irrigation in removing the intracanal bacteria.[67] Single-visit endodontics provide many potential advantages to both clinicians and patients, including a reduced flare-up rate, reduced number of appointments, and less risk of inter-appointment leakage through temporary restorations.[8910] Su et al. in 2011 explained that patients undergoing single-visit root canal therapy exhibited significantly less PEP as compared to those undergoing a two-visit treatment protocol.[11] Most studies have compared incidence, intensity, and duration of PEP on an individual scale, and it would be immensely useful to carry out a comparative analysis of these parameters as a whole to determine the most efficacious shaping technique to reduce the PEP with respect to single-visit endodontics. With all these considerations, this study was carried to compare the incidence, intensity, and duration of PEP in single-visit root canal treatment by use of manual instruments and rotary instruments in conjunction with manual syringe irrigation and ultrasonic cleaning.

SUBJECTS AND METHODS

This study was carried out in our institution, after gaining clearance from the Institutional Ethical Committee and written consent from patients. A total of 80 maxillary anterior teeth were treated with single sitting root canal treatment. Inclusion criteria for this study were – (i) between 18 and 65 years of age, (ii) maxillary permanent anterior teeth with asymptomatic irreversible pulpitis, (iii) teeth with well-formed root apex, (iv) absence of periapical radiolucency, and (v) patient without history of pain or medication in the past 5 days and exclusion criteria were – (i) internal or external resorption, (ii) calcified canals, (iii) extreme root curvature, (iv) presence of pain or tenderness in the past 5 days, (v) patients on medication for pain or infection, (vi) pregnancy, (vii) patient with history of systemic disease, (viii) root canal retreatment, and (ix) history of trauma.

Patients were divided into 2 groups, i.e. Group A (step-back method) and Group B (crown-down technique) of 40 patients in each group.

All endodontic procedure was carried out under rubber dam isolation. Before start of the procedure, all patients were administered 1.5 ml of local anesthesia (lignocaine hydrochloride and adrenaline 1:80000; Xicaine, ICPA, India). Access cavity was prepared with Endo Access bur (Dentsply International, York, PA, USA) and refined with Endo Z bur (Dentsply International, York, PA, USA) using an air-rotor handpiece. Working length was determined using radiovisiography with #15 K-file [Figure 1].

Figure 1

Materials and armamentarium used for study

Group A (step-back method)

In this group, root canal treatment was done with the step-back technique using K-file. Apical preparation was done till #50 K-file and coronal till #80 K-file. During the procedure, irrigation with manual syringe irrigation system with 30 G, side-vented needle was used. Agitation of 3% sodium hypochlorite was carried out with ultrasonic #50 K-file at the end of preparation for 1 min. After the master cone, selection canals were dried using absorbent points, and obturation was done with lateral condensation method. Postobturation restoration was done using glass ionomer restorative cement.

Group B (crown-down technique)

In this group, root canal treatment was done with crown-down technique using ProTaper Next file [Figure 2]. According to manufacturer's instructions, speed set at 300 rpm and 2.0 Ncm torque. Apical preparation was done till X5 (050/06) [Figure 3]. During the procedure, irrigation with manual syringe irrigation system with 30 G, side-vented needle was used. Agitation of 3% sodium hypochlorite was carried out with ultrasonic #50 K-file at the end of preparation for 1 min. After the master cone, selection canals were dried using absorbent points, and obturation was done by single cone method using zinc-oxide sealer. Postobturation restoration was done using glass ionomer restorative cement. Posttreatment incidence, intensity, and duration of pain at different time interval were recorded.

Figure 2

Files used for study

Figure 3

Shows preparation by rotary technique

The assessment of the pain was done using pain scale according to Ince et al.[1]

Score 0 (No pain): The treated tooth felt normal. Patients did not have any pain

Score 1 (Mild pain): Recognizable pain, but not discomforting. Pain, which required no analgesics

Score 2 (Moderate pain): Discomforting pain, but bearable. (Analgesics, if used, were effective in relieving the pain)

Score 3 (Severe pain): Difficult to bear. (Analgesics had little or no effect in relieving the pain).

RESULTS

Data were analyzed with the Chi-square test using SPSS version 16.0 SPSS 16 for Windows; (SPSS Chicago, IL, USA). Confidence interval was kept at 95%, and a P < 0.05 was considered to be statistically significant.

Incidence, intensity (mild, moderate, and severe), and duration (after 24 h, 72 h, and 7 days) were compared between above-mentioned groups.

Table 1 describes a significantly more number of patients in group treated with manual instrumentation reported pain (χ2 = 22.759; P = 0.001). Sixteen (40%) out of 40 patients in step-back and 11 (27.5%) in crown-down technique reported pain.

Table 1

Incidence of pain

Technique	Response	Frequency (%)	χ 2	P
Step back	Yes	16 (40)	22.759	0.001*
	No	24 (60)
Crown down	Yes	11 (27.5)
	No	29 (72.5)

*Confidence interval was kept at 95%, and a P < 0.05 was considered to be statistically significant

Table 2 describes duration of pain during various time intervals.

Table 2

Pain at different time intervals

Duration	Step-back technique (%)		Crown down technique (%)		χ 2	P
	Pain	No pain	Pain	No pain
After 24 h	13 (32.5)	27 (67.5)	11 (27.5)	29 (72.5)	35.604	0.001*
After 72 h	12 (30)	28 (70)	4 (10)	36 (90)	10.37	0.001*
After 7 days	5 (12.5)	35 (87.5)	2 (5)	38 (95)	14.737	0.001*

*Confidence interval was kept at 95%, and a P < 0.05 was considered to be statistically significant

When pain was assessed in step-back method, 32.5% patient after 24 h, 30% after 72 h, and 12.5% patient after 7 days reported pain, whereas 27.5%, 10%, and 5% patient experienced pain in crown-down technique after 24 h, 72 h, and 7 days, respectively. Chi-square analysis revealed statistically significant difference among the two groups in all time duration.

Table 3 shows description of intensity of pain during various time intervals. It can be concluded from table that more number of patients treated by step-back technique has mild pain as compared to patient treated by crown-down technique. The Chi-square test reveals that there existed a statistically difference among the two groups assessed for mild pain at different time interval (P = 0.001). No statistically significant differences were found between two groups for moderate pain (P = 0816). When the severe pain was measured after 24 h, 2 (5%) patients in step-back and 1 (2.5%) in crown-down technique experienced pain. It was seen that none of the patient from both the group experienced severe pain after 72 h and after 7 days.

Table 3

Intensity of postendodontic pain

	After 24 h (%)		After 72 h (%)		After 7 days (%)
	Pain	No pain	Pain	No pain	Pain	No pain
Mild pain
Step-back technique	11 (27.5)	29 (72.5)	12 (30)	28 (70)	6 (15)	34 (85)
Crown-down technique	7 (17.5)	33 (82.5)	4 (10)	36 (90)	1 (2.5)	39 (97.5)
χ2	22.369		10.37		5.812
P	0.001*		0.001*		0.001*
Moderate pain
Step-back technique	2 (5)	38 (95)	2 (5)	38 (95)	0	40 (100)
Crown-down technique	1 (2.5)	39 (97.5)	1 (2.5)	39 (97.5)	0	40 (100)
χ2	0.054		0.054		0
P	0.816		0.816		0
Severe pain
Step-back technique	2 (5)	38 (95)	0	40 (0)	0	40 (100)
Crown-down technique	1 (2.5)	39 (97.5)	0	40 (100)	0	40 (100)
χ2	32.400		0		0
P	0.001*		0		0

*Confidence interval was kept at 95%, and a P < 0.05 was considered to be statistically significant

DISCUSSION

Conventionally, root canal therapy was performed in multiple visits, now a days with the use of recent advances such as NiTi rotary instrumentation, more reliable apex locators, ultrasonics, microscopic endodontics, digital radiography, newer obturation system, and biocompatible sealing materials enable the practitioners to perform single-visit endodontics in their dental clinics. The rational for this treatment regimen includes less stress, use of single anesthesia, and less time consuming and reduces the risk of inter-appointment contaminations. All make it very well accepted by the patients.[12]

There are several factors associated with endodontic pain. The preoperative factors include acute exacerbation of chronic lesion, nonvital tooth, previously opened tooth, unusual canal anatomy, periapical cyst abscess, or fractured teeth; while the intraoperative factors include lack of isolation, apical extrusion of intracanal medicaments, irrigating solution, and infected debris, all leading to severe PEP.[13]

The mechanical and chemical factor includes incomplete debridement, periapical extrusion of contaminated debris, over instrumentation, irrigant extrusion, overextended, or underextended obturation. Evidence showed that periapical extrusion of contaminated debris during chemomechanical instrumentation was the main etiologic factor for periapical inflammation and PEP as explained by Seltzer and Naidorf 1985.[14] The debris contains necrotic dentin and bacteria that initiates the antigen-antibody reaction, triggers the complement cascade, and other inflammatory processes in the periradicular region that generates an acute inflammatory response, the intensity of which will depend on the number and/or virulence of the bacteria.[1215]

The shaping procedure itself promotes apical extrusion of debris, even when the preparation is maintained within the limits of the root canal.[2] All the instrumentation techniques result in apical extrusion of debris to some extent, no matter how much caution is given to confine the preparation to the apical terminus. Numerous authors have demonstrated that the conventional step-back technique causes more apical extrusion than other manual techniques.[1216] Sipavičiūtė and Manelienė in 2014, Alves Vde in 2010, and Reddy and Hicks in 1998 showed minimal amount of debris extrusion through the apical foramen using crown-down technique with engine-driven NiTi systems.[31718] Extrusion of debris was more with step-back technique because the K-file system acts as a piston, pushing the debris through the foramen as coronally, there was less space available to flush the debris out.[15] The removal of coronal obstructions allows for removal of bulk of tissue, debris, and microorganisms before apical shaping. Hence, the crown-down technique minimizes the extrusion of debris through the apical foramen, thereby preventing postoperative discomfort.[19] In the present study, conventional step-back technique was done with manual instrumentation using K-file system, whereas in crown-down technique cleaning and shaping was done by rotary file system, i.e. ProTaper Next.

In common clinical practice, the irrigation is delivered through manual syringe technique. The flushing action from syringe irrigation is relatively weak and dependent not only on the anatomy of the root canal but also on the depth of placement and the diameter of the needle. The only effective way to clean webs and fins is through movement of the irrigation solution, as they cannot be mechanically cleaned. Ultrasonics are a useful adjunct in cleaning these difficult anatomical features. It removes more organic tissue, planktonic bacteria, and dentin debris from the root canal. It has been demonstrated that an irrigant in conjunction with ultrasonic vibration, generates a continuous movement of the irrigant, that is directly associated with the effectiveness of the cleaning of the root canal space.[7122021]

Studies by Townsend and Maki in 2009 and Lee et al. in 2004 have shown that ultrasonic agitation was more effective than needle irrigation in removing the intracanal bacteria.[67]

Passive ultrasonic irrigation leads to higher healing rate of endodontic treatment due to more efficient removal of dentin debris and pulp tissue and bacteria from the root canal.[22] In this study, agitation of 3% sodium hypochlorite was carried out at the end of preparation for 1 min.

In this study, the incidence of pain was observed in 40% of participants treated with manual instrumentation compared to the rotary technique 27.5% (P = 0.001) showing a more statistically significant difference between both the techniques. This may be due to the fact that rotary instrument utilizes a rotational movement that results in less debris extrusion compared to the K-files that tend to push the debris periapically. This is in accordance with the study by Wei et al. who demonstrated that hand files resulted in relatively high incidence of postoperative pain than NiTi rotary files.[23]

Pain that is usually manifested a few hours or days after root canal therapy necessitates an unscheduled visit to the dentist. Hence, we have monitored the PEP form 24 h to 7 days following the root canal treatment. In the present study, the pain duration and intensity were assessed after 24 h, 72 h, and 7 days of time interval and characterized pain as mild, moderate, and severe.

The PEP was likely to occur in the first 24 h wherein the incidence rate was higher in patient treated with manual instrumentation when compared to rotary instrumentation. The PEP gradually reduces with time. Thus, it is strong indication that clinicians should not overreact to early PEP by immediately initiating endodontic retreatment procedures or extraction of the involved tooth.[24]

CONCLUSION

The incidence of pain was more in manual technique than rotary technique. The duration of pain was higher in manual group than rotary group at different time intervals. Intensities of pain, i.e. mild and severe pain, were higher in manual group than rotary group at different time intervals. From the results, we concluded that in term of PEP, single-visit endodontic therapy with rotary instrumentation appears to be more comfortable and effective procedure. Further studies are recommended in this field for further establishing the clinical significance of single-sitting endodontic procedures.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.