A Clinical Study of Bupivacaine for Mandibular Anesthesia in Oral Surgery Patrick J

A Clinical Study of Bupivacaine for Mandibular Anesthesia in Oral Surgery Patrick J. Chapman, M.B.B.S., M.D.Sc. and Alan W. Gordon Macleod, B.D.S., F.D.S.R.C.S. Department of Oral Surgery, University of Queensland Dental School, Brisbane, Australia

Summary Previous studies have shown the usefulness of bupivacaine in oral surgery. A clinical trial was con- ducted comparing bupivacaine to lidocaine in 20 patients undergoing the surgical removal of bilateral impacted mandibular third molar teeth at separate appointments. A combination analog and category pain scale was used to assess pain on four occasions over the first 24 hours following the operation. Results showed a marked reduction in postoperative pain experienced over this time and almost unani- mous patient preference for bupivacaine.

Introduction duration of anesthesia is the slow return to normal In oral surgery, the most common cause of sensation which is associated with a corresponding postoperative pain is that associated with the surgi- gradual onset of pain or discomfort.4 Also there may cal removal of impacted mandibular third molar teeth. be a period of analgesia of up to four hours after the In difficult cases, the anticipated pain sometimes dic- return of normal sensation.3 6 With lidocaine, tates that the patient be referred for general anesthe- however, severe postoperative pain often abruptly oc- sia, often as a hospital in-patient. Any practical and curs with the cessation of anesthesia, or even before safe means of reducing the duration of postoperative the anesthetic effect has completely worn off. Final- pain is advantageous to the patient, especially if the ly systemic reactions and side effects due to bupiva- intensity of the residual pain is also reduced. This caine are rare and occur no more frequently than with may be achieved by the use of long-acting local other local anesthetics.3 anesthetic agents. Additionally, prolonged local The maximum venous plasma levels of bupiva- anesthesia facilitates postoperative care such as by caine are reached within 15-30 min after injection. allowing placement of additional sutures and The half-life of bupivacaine is similar to that of lido- hemorrhage-controlling packs if needed, and main- caine, but because of the longer duration of bupiva- tenance of satisfactory oral hygiene.' Narcotic anal- caine, reinjection is needed less often and therefore, gesics are frequently used to control postoperative high plasma levels would occur less frequently.3 oral surgery pain for in-patient cases: however, this Maximum single doses of bupivacaine for the aver- is not satisfactory for out-patient cases. age adult should not exceed 200 mg without Bupivacaine is four times as potent as lidocaine at epinephrine, and 250 mg with epinephrine, repeat- equivalent doses.2'3 On this basis, 0.5% bupivacaine ed at up to 3 hr intervals, with a maximum of 400 mg should be equally as effective as 2% lidocaine. Since in 24 hr.2'3 bupivacaine is also approximately four times as tox- Laskin et al.3 reported that bupivacaine can be ic as lidocaine, their toxicities at these concentrations used clinically with less concentration of vasocon- should be equal at equivalent doses.3 It is believed strictor than lidocaine, or indeed without a vasocon- that the liver is the primary site of metabolism of strictor. In their study, there was little clinical differ- bupivacaine and up to 16% is excreted unaltered in ence when 0.25% bupivacaine without epinephrine urine.3 The times of onset of anesthesia and estab- was compared to 2% lidocaine with 1:000,000 lishment of maximum anesthesia compare favorably epinephrine. This aspect was confirmed by Chapnic to those for lidocaine, but bupivacaine produces up et aL.,6 but is disputed by Nespeca.4 to three times the duration of anesthesia.3'5'6 Another major advantage of bupivacaine besides prolonged Methods Twenty healthy adult patients, 11 males and 9 fe- males, were included for assessment of postopera- tive Accepted for publication December 26, 1984. pain following the surgical removal of bilateral Address reprint requests to Dr. Patrick Chapman, Department lower third molar teeth on two separate occasions, on of Oral Surgery, University of Queensland Dental School, Turbot average four weeks apart. The average age of the Street, Brisbane, Queensland 4000, Australia. group was approximately 21 years with a range from MARCH/APRIL 1985 69 16 to 34 years. In each case, the patients were ad- lar was rapidly and easily removed, and the resulting vised that a different local anesthetic would be used postoperative pain or discomfort was not clinically for either side. Their cooperation was sought in com- significant. pleting a combination analog and category pain scale Standard operative technique was used for on up to four occasions over the first 24 hr postoper- removal of the impacted mandibular teeth and any atively. They were not advised which type of local anesthetic problems recorded by the oral surgeons anesthetic would be used for which particular oper- involved (P.C. and A.G.M.). The patients were dis- ation or what differences they might expect to ex- charged with a 5 day course of amoxycillin (or perience. erythromycin in cases of allergy) and 16 analgesic Each patient thus acted as his/her own control with tablets containing 500 mg acetaminophen and 8 mg bupivacaine used as the local anesthetic agent on codeine phosphate in each tablet. They were instruct- one side and lidocaine used on the other side. ed to use 1 or 2 tablets up to every 3 to 4 hours as The analog pain scale, identical to the "pain ther- needed, depending on the pain intensity. No mometer" used by White and Strunin,7 is an 1 1-point postoperative sedation was used. The patients were scale, numbered 0 to 10, 0 representing no pain at seen 3-5 days postoperatively when the wound was all and 10 representing the worst pain imaginable. To examined and the pain scale returned. aid the patients' response and increase accuracy, The duration of anesthesia and analgesia was this scale was then divided into three sections such recorded from the onset of anesthesia. If a patient that 0-3 represented "mild" pain, 3-7 represented was asleep at a time when a pain recording was in- "moderate" pain, and 7-10 represented "severe" dicated, this score was registered as missing data. pain. (Figure 1). Mild pain was described as not be- The patients were also asked for their preference of ing of sufficient intensity to prevent the patient from anesthetic after both sides had been completed. concentrating on other things (e.g., reading the newspaper, etc.). Moderate pain was described as being of sufficient intensity such that the patient Results would be unable to concentrate on other things, but In no case was there failure of either anesthetic to without actually distressing the patient. Severe pain provide a satisfactory level of anesthesia, although was described as being of sufficient intensity to cause in one case each of bupivacaine and lidocaine, an ex- physical and emotional distress to the patient. tra 1 ml was required for satisfactory inferior alveo- No premedication was used for any case. The tri- lar nerve block. In all cases the operation was com- al side was injected using 0.5% bupivacaine with menced within 5 min of final injection, often sooner. 1:200,000 epinephrine, with 2.5 ml for the inferior al- The mean operating times were similar for both the veolar and lingual nerves and 0.5 ml for the buccal lidocaine cases and for the bupivacaine cases (Ta- nerve, a total of 3 ml (15 mg) for each tooth. The con- ble 1), suggesting that the operating difficulty was trol side was injected using 2% lidocaine with reasonably comparable for all cases. In fact, this was 1:80,000 epinephrine, with 2.5 ml for the inferior al- our clinical experience, except in one case (see later). veolar and lingual nerves and 0.5 ml for the buccal The mean duration of anesthesia for bupivacaine was nerve, a total of 3.0 ml (60 mg) for each tooth. 8.6 hours (over two-and-one- half times that for lido- The bupivacaine was aspirated from 10 ml am- caine) with a range of 5-13 hr. The mean duration of pules into previously emptied standard dental car- analgesia for bupivacaine was 8.3 hr (alrmost three tridges, to obviate the need for using non-dental type times that for lidocaine) with a range of 4.3-13 hours. syringes. In most cases, the onset of postoperative pain in each On some occasions the same sided maxillary third group occurred slightly prior to cessation of mental molar was removed at the same time. These patients anesthesia. were advised not to record maxillary postoperative The mean initial pain score and that recorded 4 hr pain on the pain scale, as this aspect was not being later were both significantly lower with bupivacaine investigated. In all such cases, the maxillary third mo- than with lidocaine (Table 1). Pain scores at 8 hr af-

Mild pain Moderate pain Severe pain

0 1 2 3 4 5 6 7 8 9 10 Fig. 1-Combination visual analog and category pain scale used to estimate postoperative pain intensity. 0 = no pain at all; 10 = worst pain imaginable.

70 ANESTHESIA PROGRESS TABLE 1. Comparison of Results Lidocaine 2% with Bupivacaine 0.5%/o epinephrine with epinephrine 1:80,000 1:200,000 Mean Qperating time 28.3 min 25.8 mint Mean duration of anesthesia 3.3 hr 8,6 hr*+ Mean length of analgesial 2.9 hr 8.3 hr* + Mean initial pain score 5.3 3-3 *+ Mean pain score 4 hr after 3.9 2.5#++ Initial pain score Mean pain score 8 hr after 2.8 1.7 t initial pain score Mean pain score 24 hr after 2.2 1.9 t initial pain score Mean number of analgesic tablets 6.6 required in the first 24 hr *P<0,001, paired f-test. #P<0,05 paired t-test. +P<0,01, Wilcoxon sign rank test. + +P <0,05, Wilcoxon sign rank test. tNo significant difference.

ter the initial pain onset were not significantly differ- first 24 hr, 79% was recorded by the lidocaine group ent between the two groups. At this time, in 11 of 40 and 21 % by the bupivacaine group. possible observations (20 patients x 2), patients were The mean number of analgesic tablets required in asleep and their pain scores at the time treated as the first 24 hr was significantly less for bupivacaine missing data, At 24 hr no patients were asleep, and than for lidocaine (Table 1). This reflects the reduced the pain scores again were not significantly different. intensity of postoperative pain which is also shown Of the total recorded incidence of severe pain in the in Figure 2. When the scores for both groups in Figure 2 are combined (425), almost two-thirds (62.8%) were recorded for lidocaine. Finally 19 of the 20 cases preferred bupivacaine to 300 lidocaine for postoperative pain control (p<0.001 binomial probability table) with the other case being undecided, score _267 In this patient the total pain with 250 bupivacaine was 22, while with lidocaine it was 17. This was associated with Increased operative difficulty on the side where bupivacaine was used. L 200 D Discussion la 0 158 This study was designed to compare the useful- 150 C B ness in oral surgery of the two different local anesthet- A U ic agents, lidocaine 2% with epinephrine 1:80,000 P and bupivacaine 0.5% with epinephrine 1:200,000. N Either type of local anesthetic produces approximate- ly equivalent surgical (operative) anesthesia but the E V advantage of using a long-acting local anesthtetic AI agent such as bupivacaine is that there is prolonged postoperative analgesia. The period of etfective A analgesia for bupivacaine was 8.3 hr compared to 2.9 hr for lidocaine, a difference of 5.4 hr. The over- N whelming preference for bupivacaine (95%) showed E this was an important aspect from the point of view of patients and supports Nespeca's findings.4 Besides duration of postoperative analgesia, du- Fig. 2-Sum of the pain intensity scores for each anesthetic. ration of anesthesia is also used to define and quali-

MARCH/APRIL 1985 71 fy the duration of action of local anesthetic agents. cant difference was reported by Feldmann and Nor- In this study, following inferior alveolar nerve blocks, denram.'0 Chapnick etal.6 reported that with concen- the duration of mental anesthesia was 8.6 and 3.3 hr trations of 0.5% and 0.75%, without vasoconstrictor, for bupivacaine and lidocaine, respectively, a differ- the average duration of anesthesia was 5.5 and 8.5 ence of 5.3 hr. hr, respectively.6 In clinical trials of bupivacaine for inferior alveolar nerve blocks, Heliden et al.8 using 0.25% with Conclusion 1:200,000 epinephrine reported an average duration Bupivacaine has several advantages over lido- of anesthesia of 4.75 hr and did not find any reduc- caine in oral surgery.3-5 Many oral surgical operations tion in the need for analgesics in the first postopera- are technically difficult and prolonged, resulting in tive 24 hr when compared to 2% lidocaine with considerable postoperative pain and discomfort, es- 1:80,000 epinephrine. Laskin et a/.,3 using 0.5% pecially over the first 8-12 hours. Long-acting local bupivacaine with 1:200,000 epinephrine, reported an anesthetics can eliminate a considerable amount of average duration of anesthesia of 9.5 hr following in- this unwanted experience. This was confirmed by the ferior alveolar nerve blocks with an average analgesic present study, which also showed almost complete period of just over 7.2 hr. The similar times for lido- patient preference for bupivacaine compared to caine 2% with 1:100,000 epinephrine were 3.3 hr and lidocaine. 2.9 hr, respectively. They also reported frequent cases of continued analgesia after normal sensation had returned. This was also confirmed by Chapnick Acknowledgment etal.6 Pricco5, using a similar concentration,pf bupiva- Further trials are being continued with financial support of the caine, recorded an average duration of anesthesia of Australian Dental Research Fund Incorporated. Statistical adviser, 8.85 hr, while Trieger and Gillen9 recorded an aver- Dr. M.D. Culwick. age of 7 hr. The onset of postoperative pain has been report- References 1. Meyer RA and Chinn MA: Prolonged post-operative analge- ed as more gradual with bupivacaine, compared to sia with regional nerve blocks. J Oral Surg 26(3): 182-184, lidocaine, and Nespeca4 reported the onset with 1968. bupivacaine occurs approximately 35 min before the 2. Malamed SF: Handbook ofLocalAnesthesia. C.V. Mosby, St. anesthetic effects cease. In the present study, pain Louis, 1980. onset usually occurred with bupivacaine at approxi- 3. Laskin JL, Wallace WR, De Leo B: Use of bupivacaine mately the time of cessation of anesthesia, but in 25% hydrochloride in oral surgery. J Oral Surg 35:25-29, 1977. of the patients there was a continued analgesic peri- 4. Nespeca JA: Clinical trials with bupivacaine in oral surgery. od of approximately 2 hr on average. Oral Surg 42(3):301-307, 1976. 5. Pricco DF: An evaluation of bupivacaine for regional nerve There is another important aspect highlighted in block in oral surgery. J Oral Surg. 35:126-129, 1977. this study. This is the greater protection against se- 6. Chapnick P, Baker G, Munroe CO: Bupivacaine anaesthesia vere postoperative pain in the first 24 hr when bupiva- in oral surgery. Can Dent Asso J 46:441-443, 1980. caine is used. The incidence of severe pain record- 7. White P and Strunin L: Post-anaesthetic dental extraction ed with bupivacaine was approximately 25% of that analgesia. Br J Oral Surg. 20:275-280, 1982. recorded with lidocaine. As it is especially desirable 8. Hellden L, Blomberg S, Woxberg B, Ohman A: A controlled to reduce the occurrence of severe postoperative trial of a long acting local anaesthetic (Marcaine) in oral sur- pain, this is a striking advantage with the use of gery for relief of post-operative pain. Swed Dent J 67:223-228, bupivacaine. 1974. 9. Trieger N and Gillen GH: Bupivacaine anesthesia and The ideal strength of bupivacaine in oral surgery postoperative analgesia in oral surgery. Anesth Prog 26:20- has not yet been finally decided.2 Nespeca4 stated 23, 1979. that a 0.5% concentration had a significantly longer 10. Feldman G and Nordenram A: Marcaine in oral surgery. Acta duration than the 0.25% concentration, but no signifi- Anaesth Scand (suppl.) 23:409-413, 1966.

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