Acupuncture for Postoperative Dental Pain
August 2001; Volume 4; 89-91
By Judith L. Balk, MD, FACOG
Acupuncture is used for a wide variety of painful conditions, including operative and postoperative analgesia, migraine headaches, dysmenorrhea, musculoskeletal pain, and osteoarthritis. Acupuncture’s analgesic effects on dental pain were noted in mainland China in 1966.1 Since then, multiple studies have evaluated various aspects of dental pain, including experimental and postoperative dental pain, and pain during dental procedures such as drilling into dentine, root canal, molar extraction, and tooth restoration. Ernst and Pittler have reviewed these studies.2
Acupuncture, like many pain medications, appears to be site-specific. In 1997, the NIH Consensus Development Panel on Acupuncture concluded, "Promising results have emerged, for example, efficacy of acupuncture . . . in postoperative dental pain."3 Conventional treatment for postoperative dental pain includes narcotic analgesics and nonsteroidal anti-inflammatory drugs.4 Alternatives to these agents may be preferable to some patients.
Mechanism of Action
How acupuncture achieves its analgesic effect is not well understood.
Researchers have proposed several mechanisms of action that have been reviewed extensively.5 One theory proposes that effects may be mediated through stimulation of pain receptors, thereby leading to activation of the central nervous system and induction of circulating neurochemicals. Another mechanism may occur via gate control, where large nerve fibers cause inhibition of nociceptive impulses. Also, the participation of diffuse noxious inhibitory controls may provide some analgesic effects. Lastly, some consider acupuncture’s effects to be a placebo effect. Given that acupuncture’s analgesic effects on experimental dental pain are blocked partially by naloxone, the analgesic effects likely include some opioid type of effect.6
Most studies have found acupuncture to be beneficial in reducing postoperative dental pain. An excellent recent placebo-controlled clinical trial sought to evaluate the efficacy of Chinese acupuncture in treating postoperative oral surgery (removal of a partial bony impacted third molar) pain, and the effects of psychological factors on outcomes.7
The true acupuncture procedure was manual manipulation of the acupuncture points LI-4, St-6, St-7, and SJ-17 on the tooth extraction side only. A pair of electrodes from a mock electrical stimulator was attached to the ends of the needles. For the placebo acupuncture, an empty plastic needle tube was tapped on the bony area next to each acupuncture point, and a needle with a piece of adhesive tape was then taped to the dermal surface. Again, a mock electrical stimulator was applied to the needles. "Manipulations" were created by palpating the surface of the skin with a blunt dental instrument. As explained in an earlier article, the mock electrical stimulator was used to confuse both the real and placebo acupuncture groups.8 Patients’ eyes were covered with patches so they could not view the treatment procedures.
Both the mean pain-free postoperative time and time until moderate pain were significantly longer in the acupuncture group compared with the placebo group. Also, mean time before requesting pain medication was longer in the treatment group. Average pain medication use also was significantly less in the treatment group, but total-pain-relief and pain-half-gone scores were the same in both groups.
Acupuncture seemed to be better at preventing pain rather than controlling existing pain, as acupuncture was the same as placebo in pain control after the patient reported "moderate" pain. Also, the placebo-control condition was assessed to be valid based on the high numbers of subjects who were uncertain of or incorrect about their group assignment. Lastly, outcomes did not differ based on psychological factors.
Another well-designed study was a randomized, double-blind, placebo-controlled trial of postoperative acupuncture after multiple tooth extractions.9 Subjects were enrolled after recovery from local anesthesia and were randomized to one of four groups: placebo pill plus placebo acupuncture, codeine pill plus placebo acupuncture, placebo pill plus true acupuncture, or codeine pill plus true acupuncture. All needles were stimulated manually. Pain intensity scores were recorded every 30 minutes for three hours. The placebo acupuncture point used was on the midline of the thenar web, 5 mm above the edge. This point was selected because it is close to the LI-4 point (the true acupuncture point) but is not on the large intestine meridian. For the first 30 minutes, true acupuncture alone produced the most pain relief. However, for the other time periods, true acupuncture plus codeine produced the most pain relief. True acupuncture produced significantly more pain relief than placebo acupuncture. None of the groups had complete pain relief, and it appears that the combination of acupuncture and codeine gave both short- and long-term pain relief.
In a different study, 200 patients were randomly treated with either acupuncture at LI-4 bilaterally or at LI-4 and also at tooth-specific points on the affected side.4 Pre- and post-acupuncture pain scores were compared. The median Visual Analogue Scale pain score after surgery but before acupuncture was statistically higher than after acupuncture. The tooth-specific acupuncture protocol provided more pain relief than using LI-4 alone. Plasma concentration of beta-endorphin significantly increased from baseline, but the investigators did not reveal if one acupuncture group was higher than the other. Patients were not compared to a usual care group.
A study with a different hypothesis also investigated the use of acupuncture for postoperative dental pain.10 In this study, intraoperative (as opposed to postoperative) acupuncture was compared to traditional therapy—preoperative inhalation nitrous oxide and intramuscular meperidine. Tylenol 3 was prescribed for all patients to be used as needed for postoperative pain. No differences were seen between the two groups for pain intensity or medication consumption. Both groups experienced comparable intensities of postoperative pain.
In this study, acupuncture was as effective as the sedation technique of inhaling nitrous oxide and intramuscular meperidine for postoperative pain. The authors note that meperidine’s half-life is 3.6 hours, so that no long-lasting pain relief would be expected from the traditional approach. No long-lasting effect is to be expected from intraoperative acupuncture either. The acupuncture group did not receive sedation, and the ability to perform dental procedures using only acupuncture would seem beneficial.
One opposing study, which was not placebo-controlled or blinded, found that postoperatively, patients receiving acupuncture reported greater pain intensity than a control group not receiving acupuncture.11 Acupuncture was given to 25 patients before or after removal of impacted molars. The 60 control group patients did not receive acupuncture. Patients who received acupuncture only preoperatively consumed more analgesics than the control group. Furthermore, more patients in the acupuncture groups had dry socket, a wound healing complication. The lack of blinding and placebo control increases the bias in this study. The authors suggest the following possible reasons for their findings: personality characteristics, anxiety, patient expectation, vasodilatation from the acupuncture, and acupuncture technique. The authors conclude that acupuncture is not recommended as an adjuvant in oral surgery.
The only study to report any severe complications resulting from the acupuncture was the last article, in which subjects had a higher incidence of dry socket.11 In the study utilizing a non-insertion placebo control, only the placebo group had systemic adverse effects such as dizziness, heaviness, nausea, and drowsiness.7 These effects were attributed to the dental procedure. The acupuncture group had soreness at the acupuncture sites during and after the acupuncture treatment, which according to the investigators, is expected from eliciting the de qi sensation. The de qi sensation often is described as an ache or soreness at the needle site, and many traditional Chinese medicine practitioners believe obtaining this sore or achy sensation is necessary to obtain a good result with acupuncture.
Acupuncture appears to be useful for treatment and prevention of postoperative pain after dental surgery such as tooth extraction. It may work better at preventing pain rather than treating moderate-to-severe pain. When used intraoperatively, acupuncture does not appear to change pain intensity postoperatively, but it may allow for less intraoperative medication. The length of time needed to treat, the frequency of treatments, and whether acupuncture is synergistic with conventional medicine all currently are unknown.
Acupuncture can be used either alone or as an adjunct to conventional medical treatment for pain after dental surgery. When used in combination with conventional medicine, pain relief may be optimized.
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