Anaesthetic Efficacy of Lidocaine and Articaine in Inferior Alveolar Nerve Block Combined with Buccal Infiltration in Patients with Irreversible Pulpitis.

PURPOSE: This prospective, randomized, double-blinded study was conducted to compare the anesthetic efficacy of 2% lidocaine with 1:200,000 epinephrine and 4% articaine with 1:200,000 epinephrine in inferior alveolar nerve block (IANB) combined with buccal infiltration in patients with irreversible pulpitis.
METHODS: Group I: Thirty patients received IANB of 2% lidocaine without buccal infiltration. Group II: Thirty patients received IANB of 2% lidocaine followed by buccal infiltration with 2% lidocaine. Group III: Thirty patients received IANB with 4% articaine followed by buccal infiltration with 4% articaine. Pain during the procedures was recorded by using a Heft Parker visual analog scale. No pain or mild pain on endodontic access was recorded as success and analyzed using Chi-square analysis.
RESULTS: Group I obtained 30% success rate. Fifty percent successful anesthesia was obtained for Group II. The success rate was increased to 70% for Group III with statistically significant difference among all the groups (P < 0.05).
CONCLUSION: The use of 4% articaine as both IANB and buccal infiltration recorded the highest success rate (70%) when compared to either 2% lidocaine as IANB with buccal infiltration (50%) or 2% lidocaine as IANB alone (30%) in patients with irreversible pulpitis. Copyright:

INTRODUCTION

The fundamental goal of dentists while performing endodontic therapy is to obtain an adequate pulpal anesthesia.[1] Pulpal anesthesia during posterior mandibular endodontic procedures has been traditionally achieved by inferior alveolar nerve block (IANB).[234] In irreversible pulpitis, the success rate of IANB ranges only from 19% to 56%.[5] The possible reason for the failure of IANB could be due to the existing inflammatory activation of nociceptors,[67] anatomic variations like cross and accessory innervations,[891011] and tachyphylaxis due to anesthetic solutions.[11] Therefore, it would be highly desirable to improve the success rate of IANB in endodontics.[12]

Various supporting techniques have been recommended to overcome this failure in IANB anesthesia like intra-osseous, periodontal ligament injections and these techniques require special equipment.[6] Previous studies have demonstrated that only buccal or buccal with lingual infiltrations provide successful anesthesia in 32%–67% of patients with lidocaine and 57%–92% with articaine, even without administration of standard IANB.[101314]

The introduction of articaine for dental anesthesia was introduced in the United States in 2000.[15] A study by Haas et al. found no statistical differences between 4% articaine and 4% prilocaine infiltrations in mandibular canines and second molars IN in asymptomatic patients.[89] Also, Kanaa et al. showed that 4% articaine (64.5%) produced more effective pulpal anesthesia than 2% lidocaine (38.7%) in mandibular molars after buccal infiltration in asymptomatic subjects.[10]

Several studies compared articaine either as primary IANB or as supplemental infiltration alone.[1012161718] We hypothesize that articaine usage as both IANB and supplemental infiltration would increase the success rate. Thus the aim of this study was to compare the anesthetic efficacy of 4% articaine as IANB combined with buccal infiltration and 2% lidocaine as IANB combined with buccal infiltration in mandibular molars in patients with irreversible pulpitis.

METHODS

Ninety three patients enrolled in this prospective, double blind, randomized, clinical trial. The sample size calculation was done by keeping Type I error α level at 0.05 for a two tailed test and Type II error β level at 0.20 with 80% power to detect 15% difference among the test groups. All of them were emergency patients with actively experiencing pain and were in good health without any co–morbid conditions as determined by detailed medical and dental history. An ethical clearance was sought from the institute ethical committee (REF: CSP/11/FEB/14/12) and all subjects were enrolled after a written informed consent was obtained.

Exclusion criteria included patients; below 18 years of age, with negative response to cold testing or peri–radicular pathosis (other than a widened periodontal ligament), known allergy to local anesthetics, pregnancy, significant co–morbid conditions, taking any premedication's that might interact with anesthetic assessment, active sites of pathosis in injection site and inability to sign informed consent. Inclusion criteria included vital mandibular molar tooth with moderate to severe active pain and a prolonged response to cold testing with an ice stick, and an electric pulp tester (Parkell, D624, Farmingdale, NY 11735, USA®) with vital coronal pulp tissue on access opening. The patients were asked to rate their pain on a Heft-Parker visual analog scale (HP VAS). Randomization was done by simple random sampling. A blinded dental hygienist randomly allocated the patients to the following groups:

Group I: IANB with 1.8 ml (mL) of 2% lidocaine (control group)

Group II: IANB with 1.8 mL of 2% lidocaine and 2% lidocaine as buccal infiltration

Group III: IANB with 1.8 mL of 4% articaine and 4% articaine as buccal infiltration.

Standard IANB was performed by using either “2% lidocaine with 1:200,000 epinephrine” (Lignocaine; Neon laboratories limited, Mumbai, Maharashtra, India®) or “4% articaine with 1:200,000 epinephrine” (Septanest, France®). The solution was injected by using 27 gauge long needles. Upon reaching the target area, 1.8 mL of solution was deposited at a rate of 1 mL/min after aspiration.

For buccal infiltration, the needle, with its bevel towards the bone, was gently inserted into the buccal alveolar mucosa opposite to the furcation area until it approximately reached the apical end of the roots. Followed by which aspiration was done and 1.8 mL of solution was given. In control group, the normal saline was given as buccal infiltration (placebo) to double blind the experiment. The solutions were masked with a code number by the first author while the second author performed the injections with the solutions masked with code numbers. Blinding was done by entering only the code numbers in the data sheets. After 15 min of the IANB, subjective evaluation for the presence/absence of lip numbness was done. If lip numbness was not achieved within 15 min, the block was considered unsuccessful, and the patients were excluded from the study. Rubber dam isolation was done for patients with successful anesthetic outcome and access was initiated. The patients were asked to rate any discomfort during the treatment with HP VAS.

The HP VAS consists of 170 mm line marked with various pain ratings was used in the study. The millimeter (mm) readings were removed from the scale and the scale was divided in to 4 divisions. No pain: 0 mm, mild pain: >0 mm and ≤54 mm which includes the descriptors of weak and faint pain, moderate pain: >54 mm and <114 mm and including only the descriptor of moderate pain, and severe pain: ≥114 mm and includes the descriptors of strong, intense, and maximum possible. The anesthetic efficacy of the solution was considered successful when there was “no pain” or “weak/mild” pain during endodontic access preparation and instrumentation.[12] If the patient had moderate to severe pain (VAS rating >54 mm) during the procedures, the injection was considered a failure, and an intrapulpal injection was administered. Age and initial and post injection pain were analyzed using multiple comparison analysis of variance (Kruskal–Wallis) and post hoc tests at a significant difference level of P < 0.05. Comparisons of Articaine and lidocaine solutions for anesthetic success were analyzed using Chi-square test.

RESULTS

Three patients; one from each group who did not have subjective lip numbness at 15 min were excluded from the study. There was no statistical significance comparing age (P = 0.23), sex (P = 0.87), initial (P = 0.52) and post injection pain (P = 0.17) and distribution of teeth (P = 0.86) between Groups I, II, and III [Tables 1 and 2].

Table 1

Comparison of age, sex, initial and postinjection pain in Group I, Group II and Group III

	Group I	Group II	Group III
Age	30±8	29±8	28±7
Sex
Men	16	15	17
Women	14	15	13
Initial pain (HP VAS scale)	110±35	114±30	116±29
Post injection pain (after 15 min)	11±6	10±5	10±6

There was no significant difference between the groups (P>0.05). HP VAS: Heft-parker visual analog scale

Table 2

Teeth distribution for Group I, Group II and Group III

Tooth	Group I	Group II	Group III
First molar (%)	19/30 (63.3)	20/30 (66.7)	21/30 (70)
Second molar (%)	11/30 (36.7)	10/30 (33.3)	9/30 (30)

There was no significant difference between the groups (P>0.05)

The comparison of percentage of patients with successful anesthesia (”no pain” or “weak/mild” pain during endodontic access preparation and instrumentation) between Groups I, II, III (P = 0.001) showed statistical significance P < 0.05 [Table 3].

Table 3

Percentage of successful anesthesia between Group I, Group II and Group III

Group	Success (%)	Failure (%)
I	9 (30)	21 (70)
II	15 (50)	15 (50)
III	21 (70)	9 (30)

There was a significant difference between the groups (P=0.01)

Control IANB with 2% lidocaine gave 30% success rate (9 out of 30 patients). Use of 2% Lidocaine IANB with 2% lidocaine buccal infiltration resulted in the success rate of 50% (15 out of 30 patients). But when using 4% articaine IANB with 4% articaine buccal infiltration, the success rate was increased to 70% (21 out of 30 patients) and was statistically significant with other groups; P < 0.05. 100% success rate was not achieved in any groups.

DISCUSSION

Local anesthesia using an IANB may provide successful anesthesia in 70% of uninflamed pulp, but the success rate falls drastically to 30% in irreversible pulpitis.[23411] In comparison to normal patients, patients with irreversible pulpitis have eight times more chances of local anesthestic failure.[6] The reason for failure in IANB in irreversible pulpitis may be due to local acidosis or activation of nociceptors by inflammation.[61920]

It is reasonable to effectively block the activated nociceptors by locally depositing a supplemental dose of local anesthetic solution in the vicinity of the involved tooth.[16] Various supplemental injection techniques have been suggested such as infiltration, intraligamentary, and intraosseous injections, which can actively deliver the anesthetic solution near the apices of involved teeth.[4721] In intraligamentary technique, the anesthetic solution actually diffuses along the outer surface of the cribriform plate and not through the periodontal space, with short duration of action and also with a significant incidence of postoperative pain.[162223] While intraosseous injection involves perforation into the cortical bone along with the possible risks of postoperative hyperocclusion, and infection at the site of perforation.[6] These techniques require specialized delivery equipment. Successful supplemental infiltration anesthesia of the mandibular posterior teeth would be highly advantageous in irreversible pulpitis conditions.[16]

In our study, 4% articaine IANB along with 4% articaine buccal infiltration showed higher success rate (70%) when compared with either 2% lidocaine as a IANB along with 2% lidocaine buccal infiltration (50%) or with 2% lidocaine as a IANB (30%) alone. The use of 4% articaine as an IANB along with 4% articaine buccal infiltration has increased the success rate by 70%. This is in concurrence with previous studies by Kanaa et al. which showed that articaine had a higher success rate than lidocaine in achieving buccal infiltration anesthesia of first molar in asymptomatic subjects.[10] The reason could be articaine has better bone penetration efficacy in comparison with lidocaine, which has limited diffusion through compact cortical bone.[1416] Articaine with increased liposolubility and increased degree of dissociation along with the presence of unique thiophene ring instead of benzene ring which is not possessed by other amide groups and it may facilitate better diffusion through soft and hard tissues more reliably than other local anesthetics.[81424]

The results also showed that supplemental buccal infiltration had increased the success rate for lidocaine and articaine compared to lidocaine IANB alone. This is in concurrence with previous studies, which showed that addition of supplemental buccal infiltration to IANB resulted in increased success rate.[51618] Jung et al. stated that buccal infiltration of 4% articaine with 1:100,000 adrenaline can provide a similar success rate as compared with standard IANB to anesthetize normal uninflamed mandibular first molars.[14] Thus the IANB alone will not be sufficient enough to produce adequate pulpal anesthesia in irreversible pulpitis condition. Supplemental injection techniques are often required to increase the success rate in such conditions.

The overall success rate of 70% for the 4% articaine IANB along with buccal infiltration in mandibular posterior teeth in this study is lower than the success rates of 82%–91% recorded with supplemental intraosseous anesthesia with lidocaine or articaine formulations in previous studies.[721] The reason for the higher success rates with the intraosseous injection may be attributed to the efficacy of injecting the local anesthetic solution directly into the medullary bone surrounding the apices of the teeth.[25]

CONCLUSION

The use of 4% articaine as both IANB and buccal infiltration had a significantly higher success rate (70%) when compared to either 2% lidocaine as IANB with buccal infiltration (50%) or 2% lidocaine as IANB alone (30%) in patients with irreversible pulpitis.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.