Efficacy of 2% mepivacaine and 2% lignocaine in the surgical extraction of mesioangular angulated bilaterally impacted third molars: A double-blind, randomized, clinical trial.

OBJECTIVE: The purpose of this prospective, randomized, double-blind study was to compare the anesthetic efficacy of 2% mepivacaine and 2% lidocaine (both with 1:80,000 epinephrine) for inferior alveolar nerve block in mesioangular bilaterally impacted third molar extraction. STUDY
DESIGN: Forty patients with mesioangular bilaterally impacted third molars were taken for the study; either 2% mepivacaine or 2% lidocaine is given in a double-blind manner. Surgery started 5 min after solution deposition. Success was defined as no or mild discomfort (visual analog scale [VAS] recordings) during the surgical procedure.
RESULTS: The mean time for onset period 4.2 min and 4.6 min (P = 0.018). The mean duration anesthesia 177.17 min 166.71 min (P = 0.085). No significant difference between the scores of pain reported by the patients by VAS and venovenous bypass treated with mepivacaine and lidocaine (P = 0.000). Slight increased postoperative analgesics required for mepivacaine group (4.000 tablets) and lidocaine group (4.170 tablets) (P = 0.335). The sharp increase of pulse rate with respect to both the solutions at 5 min after postinjection of local anesthetics. However, there was no statically significant difference in systolic and diastolic blood (P = 0.681) and (P = 0.270).
CONCLUSION: Lidocaine and mepivacaine with the same vasoconstrictor have similar action and both solutions are effective in surgical procedures. There were also no significant differences between them in relation to the intensity of postoperative pain.

RCT Entities:   Population Interventions Outcomes

From time immemorial, the pain control has been the subject of constant debate. In man's constant battle against pain, the greatest achievement was the discovery of anesthesia. Since then the search for an ideal anesthetic agent is in progress. A new era of local anesthetic began with the introduction of cocaine for regional nerve block in 1884 by Austrian physician Sigmund Freud (1856–1939).[1] Limitations of cocaine led to the development of newer anesthetic agents like lignocaine, which was synthesized in 1943 by a Swedish chemist Neils Lofgren.[2] Lignocaine found to be more potent and less allergic agent than procaine, replacing it as the gold standard.[1]

The improvements in agents and techniques in local anesthesia were probably the most important advances in dental sciences to have occurred in the past 100 years. The agents currently available in dentistry have most characteristics of an ideal local anesthetic.[3] Surgical extraction of bilateral impacted teeth is a common minor surgical procedure, which causes severe pain and can consequently interfere with the patient's everyday life.[4] This study was conducted to determine the efficacy of 2% lignocaine with 1:80,000 adrenaline and 2% mepivacaine with 1:80,000 adrenaline in Surgical extraction of bilateral impacted teeth.

Materials and Methods

A double-blind study was performed to evaluate the efficacy of mepivacaine and lignocaine, among 40 patients in the department of oral and maxillofacial surgery at Coorg Institute of Dental Sciences, who required surgical extractions of mesioangular bilaterally impacted third molars.

Criteria are followed in selection of patients:

Patient selected were between the age group of 40–75 years

Medically compromised patient was not considered

The patients with known history of allergy to the local anesthetic agent were excluded

The patient should be willing and co-operative

The patient should be within reach for further follow-up and assessment

No signs of inflammation in the extraction sites

From all the patients who are going to participate, a written informed consent during the pretreatment screening periods were taken.

Armamentarium

Armamentarium [Figure 1]

Local anesthetic agent

Lignocaine 2% with 1:80,000 adrenaline

Lignocaine IP - 36 mg

Adrenaline as bitartarte IP - 0.0125 mg

Nacl IP - 0.5.mg

Methylparaben - 1.0 mg

Water -1 ml.

Mepivacaine 2% with 1:80,000 adrenaline

Mepivacaine USP - 36 mg

Adrenaline USP - 0.0125 mg

Methylparaben - 1.0 mg

Water -1 ml.

Needle -26 gauge

Disposable synringes 2 ml

Visual analog scale (VAS)

Periosteal elevator/explorer.

The LA solution used in the study contained 2% mepivacaine with 1:80,000 epinephrine.[5] As the solution was not available readily, the solution was prepared by a chemist in Department of Chemistry, Sri Venkateswara University, Tirupathi. The solution was obtained as follows.

1: 1000 concentration epinephrine was diluted to 1:27,500 concentration by adding sterile water.[6] 1 ml of 1:27,500 concentration of epinephrine-containing solution was added to 2 ml of 3% mepivacaine to obtain 2% mepivacaine with 1:80,000 of epinephrine.

The investigation was conducted as a randomized, double-blind study. To avoid investigator bias and to strengthen the credibility of the patient subjective evaluation, to accomplish this goal, a special procedure was instituted.[7] The assistant covered the bottles containing the local anesthetic agents with adhesive tape. The bottle containing mepivacaine solution was marked as “B” and lidocaine containing was marked as “A.” Neither the operator nor patient knew this. This code was readily available to the principle investigator and other faculty members in case a medical emergency were to arise. Each patient was assigned a patient number depending on when he entered the study. “A master code” sheet with the numbering system and coded identity of the drugs used was maintained.[8] Blood pressure and heart rate were recorded before the administration of the local anesthetic agent and again at 5 min, 15 min, 30 min, 1 h, 2 h, after local anesthetic administration.

The standardized local anesthetic technique was used to anesthetize, inferior, alveolar, lingual, and long buccal nerves by administering 1.8 ml coded solution with a disposable syringe and needle by direct technique.[9]

Onset of anesthetic agent action (in seconds) is determined by loss of sensibility of inferior lip, corresponding half of the tongue, and the mucosa, and patient's response to a sharp explorer (pinprick testing). A 26 gauge sterile injection needle will be used for sharp objective testing on buccal attached gingival between mandibular canine and first premolar. The onset of anesthesia tested every 30 s to the time when objective test not elect any sensation. If the onset of anesthesia, total was not obtained within 10 min, anesthesia would be regarded as unsuccessful. If more than 4 ml of the solution were necessary to achieve surgical anesthesia, then the case was considered as anesthetic failure and was eliminated from the study. Postoperatively, patients were evaluated with pinpricks to establish the duration of anesthesia testing being repeated every 30 min after surgery to the time point when patients felt blunt. Sensation then continued every 10 min to no sensation.

Duration of anesthesia was calculated by taking the total time from surgical anesthesia to the time numbness wore off. The surgical procedure carried out 5 min after the onset of anesthesia. A standard procedure was done to remove the teeth followed by primary alveoloplasty.[10] All wounds were closed by continuous locking 3-0 BBS sutures. The duration of the surgical procedure was recorded from the time of incision to the last suture placed. During the procedure, intra-operative pain experience was recorded on a VAS and visual-verbal scale (VVS).

Subject receives a pain assessment form and asked to record his or her intraoperative and postoperative pain experience on VAS and VVS at intervals of 5 min, 30 min, 1 h, 2 h, 3 h. All patients are provided with analgesics medications (diclofenac sodium 50 mg 8 hourly for 3 days) and were instructed to take medications only if they felt pain. The patient is asked to note the time of the return of normal sensation to lower lip, the time of onset pain and time of first rescue medication taken. All analgesic medication taken was recorded by time. All patients receive a 5-day course of amoxicillin 500 mg 3 times daily. All patients were reviewed at 3rd and 7th postoperative days where pain assessment forms were collected.

The following parameters are assessed,

The volume of anesthetic solution used during the surgery (in ml)

Onset of anesthetic agent action (in seconds), determined by loss of sensibility of inferior lip, corresponding half of the tongue, and the mucosa, and patients response to a sharp explorer (pinprick testing). A 26 gauge sterile injection needle will be used for sharp objective testing on buccal attached gingival between mandibular canine and first premolar. The onset of anesthesia tested every 30 s to the time when objective test not elect any sensation. If the onset of anesthesia Total was not obtained within 10 min, anesthesia would be regarded as unsuccessful.

Postoperatively, patients were evaluated with pinpricks to establish the duration of anesthesia testing being repeated every 30 min after surgery to the time point when patients felt blunt. Sensation then continued every 10 min to no sensation

The intensity of anesthesia during the surgical procedure and postoperatively will be determined by 2 scores after the completion of the treatment (1) a 1–10 VAS (2) Six-point verbal rating pain scale

Systolic blood pressure, diastolic blood pressure, mean arterial pressure, heart rate are recorded before and during the administration of local anesthesia, 5 min, 15 min, 30 min, 1 h, 2 h

Postoperative pain was assessed by noting the time of intake of 1st painkiller and further intake successive of tablets.

Statistical analysis

Analysis was done taking mean values of all variables for different group separately. The significant comparison was analyzed by using the independent-samples t-test; ANOVA;[11] crosstabs procedure.[12]

Results

Following completion of the clinical study on the patients the measurement and data taken from all the patients were tabulates for statistical studies after decoding the drugs used. The various aspects of the studies were tabulated and compared.

The study comprised 26 males (57.8%) and 19 females (42.2%), found to be approximately significant (P = 0.601). The study had contained 3 patients (6.7%) in group A solution and 6 patients (13.3%) in group B solution below 45 years age; 9 patients (20%) in group A solution and 10 patients (22.2%) in group B solution between 46 and 50 years age group; 13 patients (28.9%) in group A solution and 9 patients (20.0%) in group B solution between 51-55age group; 12 patients (26.7%) in group A solution and 12 patients (26.7%) in group B solution between 56-60 age group; 8 patients (17.8%) in group A solution and 8 patients (17.8%) in group B solution above 60 years age group. The difference was found to be approximately significant (P = 0.776). The mean age of the patients group A solution was 54.78 and in group B solution was 53.64.

The mean time for onset of anesthesia with mepivacaine was 4.2 min whereas with lidocaine was 4.6 min, and the difference was statistically significant (P = 0.018).

None of the patients complained of pain sensation during incision placement and reflection of the flap, which was started 5 min after onset of anesthesia. During the elevation and removal of teeth, few patients had painful sensation. Among them 3 patients (6.7%) belonged to group A and had received lidocaine as a supplemental dose of 1.5 ml, and later on they had satisfactory anesthesia. The difference was found to be approximately significant relating to depth of anesthesia (P = 0.078). The mean duration of action of anesthesia was measured as change of sensation for onset of paresthesia of lower lip to the return of normal sensation, with mepivacaine group had 177.17 min and that of lidocaine was 166.71 min. The differences were found to be significant (P = 0.085). With regard to the course of pain, according to the patient's evaluation on VAS and venovenous bypass (VVB) scale at each determined time point, there was no significant difference between the scores of pain reported by the patients treated with mepivacaine and lidocaine (P = 0.000). The mean postoperative analgesia required in the first 3rd to 4th postoperative hour was same for mepivacaine group (4.000 tablets) and lidocaine group (4.170 tablets). The difference was found to be statistically insignificant (P = 0.335).

With respect to hemodynamic changes, there was a sharp increase of pulse rate with respect to both the solutions at 5 min after postinjection of local anesthetics.[13] However, there was no statically significant difference in systolic and diastolic blood pressure before, during the surgery and after the suture placement for both groups (P = 0.681) and (P = 0.270) [Tables 1–7 and Graphs 1–8]

Table 1

Age distribution

Table 7

Postoperative pain score (VVB scale)

Graph 1

Age distribution

Graph 8

Postoperative pain score (VVB scale) graph. VVB: Venovenous bypass

Onset of anesthesia graph

Duration of anesthesia

Comparison of systolic blood pressure graph

Comparison of diastolic blood pressure graph

Postoperative pain score (VAS scale) graph. VAS: Visual analog scale

Discussion

Dental profession is one among the branches of healing sciences, where clinicians are more likely to be continuously and directly involved with pain, fear, and anxiety in the ambulatory and otherwise healthy patients. Certainly pain in difficult, if not impossible, to quantify and OKESON has stated that “pain is personal psychological experience and observe can play no legitimate part in the direct measurement. The overall control of pain in minor oral surgical procedures, besides of the tissue handling, consists of the ability to place accurately an anesthetic solution in proper anatomical relationship to the structures to be operated upon. Despite this, there is no doubt that the majority of patients who now attend for treatment can be managed without resort to anything other than the conventional method of regional blockage or local analgesia.

The present study was done to determine the effectiveness of 2% mepivacaine with 1:80,000 adrenaline in comparison with lidocaine hydrochloride with 1:80,000 adrenaline, as local anesthetics in surgical extraction of bilateral mesioangular impacted third molars. Mepivacaine belongs to amide group of local anesthetics, which acts by decreasing the rate of depolarization of action potential in nerve fibers by impending the initial rise in sodium conductance, thus preventing the generation of conduction of nerve impulses.[14] The lipid solubility is the most important determinant of anesthetic potency. The potency of mepivacaine is approximately slightly more or equal to that of lidocaine.[14]

The degree of the protein binding of a local anesthetic directly determines the duration of anesthesia. Mepivacaine has got a high affinity for the protein components of nerve and, therefore, is less liable to diffuse from the injection site and be absorbed into systemic circulation. The mean duration of anesthesia for mepivacaine in this study was 177.17 min. Thus, the duration of action of mepivacaine is slightly greater than the duration of lignocaine.[15] This does not coincide with the earlier studies of Gabreilo,[16] Bella.[17]

Mepivacaine was found to provide satisfactory anesthesia in the present study without the occurrence of any complication or side effects. The depth of anesthesia of intra-operative anesthesia with mepivacaine has been found to be superior to that with lidocaine in previous studies.[16171819]

Postoperative pain assessments were made using a standard VAS and VVS, which are sensitive to and simple means of pain assessment. The result showed there was a significant reduction in pain, experienced by mepivacaine group between 2 and 3 h postoperatively. Maximum postoperative pain is usually experienced in the first 6–8 h. The use of mepivacaine with a longer duration of action reduces the postoperative pain, discomfort, and analgesic intake during the immediate postoperative period. In the present study, the mean analgesic consumption for the first 4 days shows less for mepivacaine group (4.000 tablets) compared to lidocaine group (4.170 tablets). The difference was found to be statistically insignificant (P = 0.335). This is in tune with the earlier studies of Porto et al.[16]

Although the anesthetic agent does not have effect on pain and inflammation directly, longer-acting local anesthetics may allow the patients to rest more easily and thus permit the body to withstand pain more effectively during the 1st postoperative day. The mean systolic and diastolic blood pressure remained relatively constant in the current study, and no statistically significant differences were found between the two local anesthetic agents. This is in agreement with other authors who reported no change in blood pressure with the administration of adrenaline containing a local anesthetic.[19]

Conclusion

Lidocaine and mepivacaine with the same vasoconstrictor have similar action and both solutions are effective in surgical procedures. There were also no significant differences between them in relation to the intensity of postoperative pain.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Table 2

Sex distribution

Table 3

Onset and duration of anesthesia tables

Table 4

Comparison of blood pressure tables

Table 5

Comparison of diastolic blood pressure

Table 6

Postoperative pain score (VAS scale)