Pain management and endodontic therapy - A dentist's perspective

The last decade has noted the increasing popularity of root canal therap (RCT) owing to a growing awareness among patients to save their teeth. With dentistry focusing more and more on conservative approaches, RCT has now become a daily routine procedure in dental clinics.

Despite technological advances, the number of patients anticipating as well as experiencing pain during root canals remains relatively high (1). A recent survey by the American Association of Endodontists (AAE) has highlighted that 67% of patients declared the 'fear of pain' as their primary concern regarding root canal treatment (1). The heightened expectations of patients to undergo painless root canal therapy and the need to keep intraoperative and postoperative pain and complications to a bare minimum have made adequate pain control an absolute essential.

Good pain control is not only needed during the therapy, rather the success of an endodontic therapy relies equally on optimum pain management before and after the therapy (1). Therefore, the management of a patient requiring root canal treatment where pain may be experienced needs careful consideration and prior planning by the dentist.

Acknowledging this fact, dentists have used a combination strategy consisting of the use of premedication with analgesics, standard local anesthetic solutions, anxiety reduction techniques, and injections during therapy, coupled with flexible post-operative pain management, that caters for the individual patient and the specific conditions being treated (1,2).

MOA of analgesics-How do NSAIDS act?

Studies have revealed strikingly diverse prevalence rates ranging from 11% to 35% and even as high as 100% for patients experiencing moderate to severe dental pain, depending on the condition being treated –teeth with irreversible pulpitis and acute apical periodontitis were significantly associated with more treatment pain than teeth that had pulpless and infected canals with apical periodontitis (1).

Successful anesthesia remains a cornerstone for painless endodontic treatment. High levels of anxiety due to 'fear of pain', coupled with the effects of inflammation, decrease the patients' pain threshold and diminish the effect of local anesthesia. Teeth with inflamed pulps also have significantly increased tetrodotoxin-resistant sodium channels (voltage-gated Na+ channels), which are responsible for increased pain perception (hyperalgesia and allodynia) and can decrease nerve responses to anesthetic agents. (2)

Considering such scenarios, dentists continuously strive to minimize the nociceptive input by using non-steroidal anti-inflammatory drugs (NSAIDs) since they prevent the formation of prostaglandins at the site of treatment or injury (1). Traditional NSAIDs inhibit the cyclo-oxygenase pathway responsible for generating mediators for inflammation and pain (3). Among the NSAIDs, Ibuprofen is generally considered to be a safer drug with few side effects. It is a widely available OTC painkiller and therefore is the recommended drug if premedication is to be used (1,3).

Recent evidence suggests that acetaminophen (commonly known as paracetamol), though not categorized as an NSAID, functions in part by blocking prostaglandin synthesis through the inhibition of COX-1 and COX-2, with additional activity linked to the central nervous system via endogenous neurotransmitter systems (3). Acting synergistically, a growing body of research now confirms that combining ibuprofen and acetaminophen produces greater peak analgesia and more consistent analgesia (i.e., less variability between patients) without increasing adverse side effects (4).

Study testimonials- Following diagnosis, proper consideration should be given to the use of pre-operative medication to reduce pain and inflammation at the treatment site. NSAIDs are among the most widely studied drugs for pain-alleviation, based on their ability to reduce the amount of prostaglandin in the inflamed pulp, thus blocking the inflammatory process (3).

Preoperative pain management-Several researchers have associated the use of ibuprofen premedication with an increased success rate for local anesthesia during root canal therapy (1) The fact that NSAIDs possess a greater efficacy than opioids in the treatment of severe dental pain has been another eye-opener (5).

1. A study by Parirokh et al. (6), including only irreversible pulpitis cases that had no spontaneous pain, reported a significant benefit from premedication with ibuprofen. The team confirmed that in earlier stages of irreversible pulpitis when there is no spontaneous pain, premedication helps to increase the success of local anesthesia dramatically.
2. Supporting the above results, a meta-analysis concluded that 600–800 mg ibuprofen was among the few NSAIDs that significantly increased the success rate of Inferior alveolar nerve blocks(IANB) (1).
3. Buschang et. al. found that the combination of 600 mg of ibuprofen and 1000 mg of acetaminophen was more effective at pain relief than 600 mg of ibuprofen alone (7) Therefore, an effective strategy for managing emergency pain patients is the combined use of ibuprofen and acetaminophen.
4. Supporting the above, another study carried out Derry.et.al, revealed that combinations such as ibuprofen 200 mg + acetaminophen 500 mg, up to ibuprofen 400 mg + acetaminophen 1,000 mg, have been shown to produce highly significant analgesic benefits (4).

Postoperative pain management-Studies have reported that some degree of postoperative discomfort is normal. The majority of the patients have some moderate discomfort after endodontic treatment with no greater effect on daily living (5). Research has further highlighted that patients who present with moderate to severe pain are five times more likely to experience moderate-severe operative and post-operative pain, even if ideal treatment is provided. Such situations call for optimized postoperative pain management, usually best achieved with NSAIDs such as ibuprofen, provided an adequate dose is taken (1).

A meta-analysis done by Smith et al aimed at finding an optimal regimen of non-opioid analgesics as a first-line palliative treatment for unavoidable post-operative endodontic discomfort, highlighted that ibuprofen 600 mg alone as well as a combination of ibuprofen 600mg and acetaminophen 1000mg is more effective than placebo in reducing post-operative endodontic pain (3). The team further confirmed that the single most effective drug regimen with the greatest decrease in pain at 6 hours post-operative was ibuprofen 200mg+acetaminophen 325mg with a 43 VAS point pain reduction relative to placebo on a 100mm VAS scale.

Drug dosages and the recommendations-The maximum recommended dosage of ibuprofen is 3200 mg/day, with common dosages ranging from 400 mg to 800 mg every 4 to 8 hours (5).

Combination therapy-Mild to moderate pain is often relieved by 400 mg ibuprofen combined with 325 mg acetaminophen dosed every 6 hours, whereas more severe pain may require 600 mg or 800 mg ibuprofen and up to 1000 mg acetaminophen every 8 hours (5). Simultaneous administration of ibuprofen and acetaminophen has shown improved efficacy over alternating courses and is usually encouraged (5).

Take home message-

Endodontic procedures are the critical first step in treating and restoring a tooth with a root canal system irreversibly affected by infection and inflammation.

Pain in dental therapy may be associated with the procedure as well as postoperatively. Successful endodontic treatment includes the management of both pre and post-operative pain and symptoms that address both the patient's primary concern and potential long-term complications such as chronic pain.

Non-steroidal anti-inflammatory drugs (NSAIDs) are one of the most recommended classes of pain-relievers in dentistry today. They function by inhibiting the cyclooxygenase enzymes and preventing the generation of new prostaglandin molecules.

Ibuprofen, in dual therapy with acetaminophen, has been the most effective drug therapy for alleviation of pain.

Concluding remarks-It is imperative that dentists strive to improve the treatment experience for their patients by utilizing strategies to reduce pain during treatment. The essence of this also lies in having an accurate diagnosis and a thorough understanding of the various conditions that affect the pulp and root canal system. Being the most widely studied drug with relative safety and tolerability, ibuprofen acetaminophen combination has cemented a firm hold among dentists worldwide as the 'go to' drugs for managing pre, intra, and post-op pain during endodontic procedures.

References

1. Abbott, P. V., & Parirokh, M. (2018). Strategies for managing pain during endodontic treatment. Australian Endodontic Journal, 44(2), 99-113.

2. Subbiya A, Pradeepkumar AR. Pain Management in Endodontics. J Oper Dent Endod 2016;1(2):76-81.

3. Smith, E. A., Marshall, J. G., Selph, S. S., Barker, D. R., & Sedgley, C. M. (2017). Nonsteroidal anti-inflammatory drugs for managing postoperative endodontic pain in patients who present with preoperative pain: a systematic review and meta-analysis. Journal of endodontics, 43(1), 7-15.

4. Derry, C. J., Derry, S., & Moore, R. A. (2013). Single dose oral ibuprofen plus paracetamol (acetaminophen) for acute postoperative pain. The Cochrane database of systematic reviews, 2013(6), CD010210.

5. Blicher, B., & Pryles, R. L. (2020). Endodontic Pain Management: Preoperative, Perioperative, and Postoperative Strategies. Compendium, 41(4).

6. Parirokh M, Ashouri R, Rekabi AR et al. The effect of premedication with ibuprofen and indomethacin on the success of inferior alveolar nerve block for teeth with irreversible pulpitis. J Endod 2010; 36: 1450–4.

7. Katz, S. J. Analgesics: Balancing the Equation.