Changing Paradigms for Acute Dental Pain: Prevention Is Better Than PRN.

A B S T R A C T The drugs available for the management of acute orofacial pain have changed very little since the introduction of ibuprofen into practice 40 years ago. Orally effective opioids, acetaminophen, aspirin and NSAIDs remain the mainstay of analgesic therapy. Increased recognition of the societal and personal impact of opioid diversion and abuse requires re-examination of the traditional approach of prescribing an opioid-containing analgesic combination to be administered by the patient "as needed" (PRN) starting postoperatively.

Evidence-based clinical practice guideline for the pharmacologic management of acute dental pain in adolescents, adults, and older adults: A report from the American Dental Association Science and Research Institute, the University of Pittsburgh, and the University of Pennsylvania.

BACKGROUND: A panel convened by the American Dental Association Science and Research Institute, the University of Pittsburgh, and the University of Pennsylvania conducted systematic reviews and meta-analyses and formulated evidence-based recommendations for the pharmacologic management of acute dental pain after simple and surgical tooth extraction(s) and for the temporary management (ie, definitive dental treatment not immediately available) of toothache associated with pulp and periapical diseases in adolescents, adults, and older adults. TYPES OF STUDIES REVIEWED: The panel conducted 4 systematic reviews to determine the effect of opioid and nonopioid analgesics, local anesthetics, corticosteroids, and topical anesthetics on acute dental pain. The panel used the Grading of Recommendations, Assessment, Development and Evaluation approach to assess the certainty of the evidence and the Grading of Recommendations, Assessment, Development and Evaluation Evidence-to-Decision Framework to formulate recommendations. RESULTS: The panel formulated recommendations and good practice statements using the best available evidence. There is a beneficial net balance favoring the use of nonopioid medications compared with opioid medications. In particular, nonsteroidal anti-inflammatory drugs alone or in combination with acetaminophen likely provide superior pain relief with a more favorable safety profile than opioids. CONCLUSIONS AND PRACTICAL IMPLICATIONS: Nonopioid medications are first-line therapy for managing acute dental pain after tooth extraction(s) and the temporary management of toothache. The use of opioids should be reserved for clinical situations when the first-line therapy is insufficient to reduce pain or there is contraindication of nonsteroidal anti-inflammatory drugs. Clinicians should avoid the routine use of just-in-case prescribing of opioids and should exert extreme caution when prescribing opioids to adolescents and young adults.

Evidence-based clinical practice guideline for the pharmacologic management of acute dental pain in children: A report from the American Dental Association Science and Research Institute, the University of Pittsburgh School of Dental Medicine, and the Center for Integrative Global Oral Health at the University of Pennsylvania.

BACKGROUND: A guideline panel convened by the American Dental Association Council on Scientific Affairs, American Dental Association Science and Research Institute, University of Pittsburgh School of Dental Medicine, and Center for Integrative Global Oral Health at the University of Pennsylvania conducted a systematic review and meta-analyses and formulated evidence-based recommendations for the pharmacologic management of acute dental pain after 1 or more simple and surgical tooth extractions and the temporary management of toothache (that is, when definitive dental treatment not immediately available) associated with pulp and furcation or periapical diseases in children (< 12 years). TYPES OF STUDIES REVIEWED: The authors conducted a systematic review to determine the effect of analgesics and corticosteroids in managing acute dental pain. They used the Grading of Recommendations Assessment, Development and Evaluation approach to assess the certainty of the evidence and the Grading of Recommendations Assessment, Development and Evaluation Evidence to Decision framework to formulate recommendations. RESULTS: The panel formulated 7 recommendations and 5 good practice statements across conditions. There is a small beneficial net balance favoring the use of nonsteroidal anti-inflammatory drugs alone or in combination with acetaminophen compared with not providing analgesic therapy. There is no available evidence regarding the effect of corticosteroids on acute pain after surgical tooth extractions in children. CONCLUSIONS AND PRACTICAL IMPLICATIONS: Nonopioid medications, specifically nonsteroidal anti-inflammatory drugs like ibuprofen and naproxen alone or in combination with acetaminophen, are recommended for managing acute dental pain after 1 or more tooth extractions (that is, simple and surgical) and the temporary management of toothache in children (conditional recommendation, very low certainty). According to the US Food and Drug Administration, the use of codeine and tramadol in children for managing acute pain is contraindicated.

Nitric oxide is negatively correlated to pain during acute inflammation.

BACKGROUND: The role that nitric oxide (NO) plays in modulating pain in the periphery is unclear. We show here, the results of two independent clinical studies (microdialysis and gene expression studies) and a pilot dose finding study (glyceryl trinitrate study), to study the role of NO in the early phase of acute inflammatory pain following oral surgery. The effect of ketorolac on NO production and nitric oxide synthase (NOS) gene expression was also studied. RESULTS: Microdialysis samples showed significantly higher levels of NO at the first 100 min compared to the last 80 minutes in the placebo treated group. In the ketorolac group, on the other hand, NO levels gradually decreased over the first 60 min but were similar to placebo over the later 100-180 min, with no significant change in NO level over time. The levels of NO were negatively correlated to pain intensity scores. Local infusion of the NO donor glyceryl trinitrate at the site of surgery, showed a small analgesic effect that did not reach statistical significance in the sample size used. While the gene expression of iNOS and eNOS were not up-regulated, 3 hours after surgery, nNOS was downregulated in both treatment groups and eNOS gene expression was significantly lower in the ketorolac group compared to the placebo group. Further, there was a positive correlation between the change in gene expression of nNOS and eNOS in the placebo group but not in the ketorolac group. CONCLUSION: We suggest that at this early stage of inflammatory pain in man, NO is analgesic in the periphery. Further, ketorolac down-regulates eNOS gene expression.

Kinin B1 receptors contributes to acute pain following minor surgery in humans.

BACKGROUND: Kinins play an important role in regulation of pain and hyperalgesia after tissue injury and inflammation by activating two types of G-protein-coupled receptors, the kinin B1 and B2 receptors. It is generally accepted that the B2 receptor is constitutively expressed, whereas the B1 receptor is induced in response to inflammation. However, little is known about the regulatory effects of kinin receptors on the onset of acute inflammation and inflammatory pain in humans. The present study investigated the changes in gene expression of kinin receptors and the levels of their endogenous ligands at an early time point following tissue injury and their relation to clinical pain, as well as the effect of COX-inhibition on their expression levels. RESULTS: Tissue injury resulted in a significant up-regulation in the gene expression of B1 and B2 receptors at 3 hours post-surgery, the onset of acute inflammatory pain. Interestingly, the up-regulation in the gene expression of B1 and B2 receptors was positively correlated to pain intensity only after ketorolac treatment, signifying an interaction between prostaglandins and kinins in the inflammatory pain process. Further, the gene expression of both B1 and B2 receptors were correlated. Following tissue injury, B1 ligands des-Arg9-BK and des-Arg10-KD were significantly lower at the third hour compared to the first 2 hours in both the placebo and the ketorolac treatment groups but did not differ significantly between groups. Tissue injury also resulted in the down-regulation of TRPV1 gene expression at 3 hours post-surgery with no significant effect by ketorolac treatment. Interestingly, the change in gene expression of TRPV1 was correlated to the change in gene expression of B1 receptor but not B2 receptor. CONCLUSIONS: These results provide evidence at the transcriptional level in a clinical model of tissue injury that up-regulation of kinin receptors are involved in the development of the early phase of inflammation and inflammatory pain. The up-regulation of B1 receptors may contribute to acute inflammatory pain through TRPV1 activation.

Stimulating the development of mechanism-based, individualized pain therapies.

Biomedical science has greatly improved our understanding of pain in recent decades, but few novel molecular entities that address fundamentally new pain mechanisms have entered the clinic, despite dramatically increased pharmaceutical investment. Indeed, virtually all new analgesics approved over the past 25 years are derivatives or reformulations of opioids or aspirin-like drugs, existing drugs given for a new indication or older drugs given by a different route of administration. Here, we discuss factors contributing to this lack of innovation in therapies for pain and advocate public-private partnerships (PPPs) to translate new knowledge into more efficacious and safer treatments.

Genome-wide screen identifies drug-induced regulation of the gene giant axonal neuropathy (Gan) in a mouse model of antiretroviral-induced painful peripheral neuropathy.

Painful peripheral neuropathy is a debilitating complication of the treatment of HIV with nucleoside reverse transcriptase inhibitors (NRTIs). Patients are living longer with these drugs; however many develop excruciating, unremitting, and often treatment-limiting neuropathy that is resistant to conventional pain management therapies. Improving patient comfort and quality of life is paramount and depends on a clearer understanding of this devastating side effect. The mechanisms underlying the development of NRTI-induced neuropathy, however, remain unclear. Using a mouse model of NRTI-induced neuropathy, the authors conducted an unbiased whole-genome microarray screen to identify molecular targets in the spinal dorsal horn, which is the location where integration of ascending sensory transmission and descending modulatory effects occur. Analysis of the microarray data identified a change in the gene giant axonal neuropathy 1 (Gan1). Mutation of this gene has been linked to the development of giant axonal neuropathy (GAN), a rare autosomal recessive condition characterized by a progressive sensorimotor neuropathy. Gan1 has not been previously linked to nerve pathologies in other populations. In this study, downregulation of the Gan1 gene and the gene protein product, gigaxonin, was validated via quantitative polymerase chain reaction ([qPCR] gene expression) and Western blot analyses (protein level). Our report is the first to suggest that Gan1 might be a novel molecular target in the development of NRTI-induced peripheral neuropathy with implications for new therapeutic approaches to preventing or reducing a significant side effect of HIV treatment.

Individualized pain medicine.

Since the first draft of the human genome was published 10 years ago, scientists have tried to develop new treatment strategies for various types of diseases based on individual genomes. It is called personalized (or individualized) medicine and is expected to increase efficacy and reduce adverse reactions of drugs. Much progress has been made with newly developed technologies, though individualized pain medicine is still far from realization. Efforts on the integrative genomic analyses along with understandings of interactions between other related factors such as environment will eventually translate complex genomic information into individualized pain medicine.

The differential effects of bupivacaine and lidocaine on prostaglandin E2 release, cyclooxygenase gene expression and pain in a clinical pain model.

BACKGROUND: In addition to blocking nociceptive input from surgical sites, long-acting local anesthetics might directly modulate inflammation. In the present study, we describe the proinflammatory effects of bupivacaine on local prostaglandin E2 (PGE2) production and cyclooxygenase (COX) gene expression that increases postoperative pain in human subjects. METHODS: Subjects (n = 114) undergoing extraction of impacted third molars received either 2% lidocaine or 0.5% bupivacaine before surgery and either rofecoxib 50 mg or placebo orally 90 min before surgery and for the following 48 h. Oral mucosal biopsies were taken before surgery and 48 h after surgery. After extraction, a microdialysis probe was placed at the surgical site for PGE2 and thromboxane B2 (TXB2) measurements. RESULTS: The bupivacaine/rofecoxib group reported significantly less pain, as assessed by a visual analog scale, compared with the other three treatment groups over the first 4 h. However, the bupivacaine/placebo group reported significantly more pain at 24 h and PGE2 levels during the first 4 h were significantly higher than the other three treatment groups. Moreover, bupivacaine significantly increased COX-2 gene expression at 48 h as compared with the lidocaine/placebo group. Thromboxane levels were not significantly affected by any of the treatments, indicating that the effects seen were attributable to inhibition of COX-2, but not COX-1. CONCLUSIONS: These results suggest that bupivacaine stimulates COX-2 gene expression after tissue injury, which is associated with higher PGE2 production and pain after the local anesthetic effect dissipates.

Lack of influence of GTP cyclohydrolase gene (GCH1) variations on pain sensitivity in humans.

OBJECTIVES: To assess the effect of variations in GTP cyclohydrolase gene (GCH1) on pain sensitivity in humans. METHODS: Thermal and cold pain sensitivity were evaluated in a cohort of 735 healthy volunteers. Among this cohort, the clinical pain responses of 221 subjects after the surgical removal of impacted third molars were evaluated. Genotyping was done for 38 single nucleotide polymorphisms (SNPs) whose heterozygosity > 0.2 in GCH1. Influence of the genetic variations including SNPs and haplotypes on pain sensitivity were analyzed. RESULTS: Minor allele frequencies and linkage disequilibrium show significant differences in European Americans, African Americans, Hispanic Americans and Asian Americans. Association analyses in European Americans do not replicate the previously reported important influence of GCH1 variations on pain sensitivity. CONCLUSION: Considering population stratification, previously reported associations between GCH1 genetic variations and pain sensitivity appear weak or negligible in this well characterized model of pain.

Expression of COX-1 and COX-2 in a clinical model of acute inflammation.

UNLABELLED: Cyclooxygenase (COX) plays an important role in the induction of pain and inflammation as well as the analgesic actions of NSAIDs and coxibs. This study evaluates the expression of the two isoforms COX-1 and COX-2 in a clinical model in which the surgical removal of impacted third molars is used to evaluate the analgesic activity of anti-inflammatory drugs. A 3-mm punch biopsy was performed on the oral mucosa overlying 1 impacted third molar immediately before extraction of 2 impacted lower third molars. After the second tooth was extracted, a second biopsy was performed adjacent to the surgical site either immediately after surgery or 30, 60, or 120 minutes after surgery. RNA was extracted from the biopsy specimens, and RT-PCR was performed to assess mRNA levels of COX-1, COX-2, and glyceraldehyde-3-phosphate dehydrogenase (G3PDH). The RT-PCR products in the biopsy specimens were normalized to G3PDH and compared with baseline. COX-2 mRNA was progressively increased at 30, 60, and 120 minutes after surgery (P<.05); COX-1 mRNA was transiently decreased at 60 minutes during the postsurgical period (P<.05). The results demonstrate peripheral elevation of COX-2 after tissue injury, which may contribute to increased prostaglandin E(2) at the site of injury, pain onset, and the analgesic activity of both nonselective NSAIDs and selective COX-2 inhibitors. PERSPECTIVE: This clinical study uses a physiologically relevant model to determine the time course of expression of COX-1 and COX-2 in acute inflammation of the human oral mucosa. This study furthers our understanding of the contribution of the COX isoforms to acute pain.

Individual responder analyses for pain: does one pain scale fit all?

The outcomes of clinical trials are based on the mean responses of large numbers of subjects but fail to address inter-individual differences. The molecular mechanisms that underlie pain vary among individuals over time and among different types of pain to produce wide inter-individual variations in pain perception and response. Gender, ethnicity, temperament and genetic factors also contribute to individual variation in pain sensitivity and responses to analgesics. Pain measurement scales can be used differently across individuals based on the past pain experiences of individuals. We propose that individual responder analyses could be used in clinical trials to better detect analgesic activity across patient groups and within sub-groups, and to identify molecular-genetic mechanisms that contribute to individual variation.

Genetic polymorphisms in monoamine neurotransmitter systems show only weak association with acute post-surgical pain in humans.

BACKGROUND: Candidate gene studies on the basis of biological hypotheses have been a practical approach to identify relevant genetic variation in complex traits. Based on previous reports and the roles in pain pathways, we have examined the effects of variations of loci in the genes of monoamine neurotransmitter systems including metabolizing enzymes, receptors and transporters on acute clinical pain responses in humans. RESULTS: Variations in the catecholamine metabolizing enzyme genes (MAOA and COMT) showed significant associations with the maximum post-operative pain rating while the serotonin transporter gene (SLC6A4) showed association with the onset time of post-operative pain. Analgesic onset time after medication was significantly associated with the norepinephrine transporter gene (SLC6A2). However, the association between COMT genetic variation and pain sensitivity in our study differ from previous studies with small sample sizes, population stratification and pain phenotype derived from combining different types of pain stimuli. Correcting for multiple comparisons did not sustain these genetic associations between monoamine neurotransmitter systems and pain sensitivity even in this large and homogeneous sample. CONCLUSION: These results suggest that the previously reported associations between genetic polymorphisms in the monoamine neurotransmitter systems and the interindividual variability in pain responses cannot be replicated in a clinically relevant pain phenotype.

Rofecoxib regulates the expression of genes related to the matrix metalloproteinase pathway in humans: implication for the adverse effects of cyclooxygenase-2 inhibitors.

BACKGROUND: Cyclooxygenase-2 (COX-2) and COX-2-derived prostaglandins contribute to acute inflammation and pain, as well as resolution of inflammation; inhibition of COX-2 results in persistence of inflammation. Because matrix metalloproteinases (MMPs) play an essential role in inflammatory tissue injury and their activity is regulated by COX-2-derived prostaglandin E2, we evaluated whether COX-2 inhibition is associated with MMP overexpression during acute inflammation. METHODS: A total of 102 oral mucosal biopsy specimens were taken from 51 healthy volunteers who required extraction of impacted third molars. Subjects randomly received either rofecoxib (50 mg daily), ibuprofen (400 mg 4 times per day), or placebo 90 minutes before surgery and up to 48 hours after surgery. Total ribonucleic acid extracted from each biopsy specimen was used to analyze changes in gene expression related to the MMP pathway after tissue injury and drug treatments by use of microarray and quantitative real-time polymerase chain reaction in this clinical model of acute inflammation. RESULTS: Following tissue injury, rofecoxib increased the expression of genes associated with degradation of the extracellular matrix, including MMP-1 (64.7 +/- 6.5, P = .010), MMP-3 (41.7 +/- 4.8, P = .007), PLAT (encoding tissue plasminogen activator) (10.9 +/- 4.6, P = .032), and IL8 (encoding interleukin 8) (8.3 +/- 6.7, P = .020), and decreased the expression of TIMP3 (encoding tissue inhibitor of metalloproteinase 3) (6.2 +/- 2.8, P = .027). Ibuprofen produced similar effects on the expression of MMP-1 (23.4 +/- 5.0, P = .016) and MMP-3 (26.3 +/- 4.2, P = .003). In contrast, the expression of these genes was not statistically changed after tissue injury in the placebo group. The microarray data were in concordance with the changes in gene expression confirmed by quantitative real-time polymerase chain reaction. CONCLUSION: These findings provide evidence at the transcriptional level that inhibition of COX-2, in the presence of acute inflammation, induces changes in gene expression related to the MMP pathway. These changes may contribute to the adverse effects attributed to COX-2 inhibition by interfering with resolution of inflammation.

Genetically mediated interindividual variation in analgesic responses to cyclooxygenase inhibitory drugs.

BACKGROUND: Wide interindividual variation in responses to cyclooxygenase (COX) inhibitory drugs limits their clinical utility and safety. METHODS: To better understand the molecular responses to COX inhibition, we analyzed the gene expression level of the genes encoding enzymes related to prostaglandin production including the COX-1 gene (PTGS1) and the COX-2 gene (PTGS2), as well as their genetic polymorphisms, and the analgesic response to COX inhibitory drugs such as ibuprofen or rofecoxib or to placebo after minor surgery. RESULTS: Notable heterogeneity in global gene expression was evident between subjects. At 2 to 4 hours after surgery, PTGS1 expression was slightly decreased (36%, P < .001) and PTGS2 expression was markedly increased (300%, P < .001) with wide interindividual variation; at 48 hours after surgery, little detectable change in PTGS1 and PTGS2 expression was found in the control group. However, ibuprofen and rofecoxib treatment significantly increased PTGS2 expression at 48 hours (P = .001 and P = .049, respectively). At 2 to 4 hours after surgery, patients with the G/G allele at the nucleotide position of -765G>C in PTGS2 showed a significantly higher increase in PTGS2 expression (P = .012) compared with G/C and C/C patients, although all of them showed an increase in PTGS2 expression (P < .001 and P = .043, respectively). Among G/G patients, rofecoxib administration resulted in significantly lower pain intensity on a visual analog scale (7.2 +/- 2.5 mm) (P = .008) at 48 hours after surgery, as compared with ibuprofen administration (31.3 +/- 6.7 mm). The finding regarding pain intensity at 48 hours in G/C and C/C patients was opposite (P = .002), being greater in the rofecoxib group (37 +/- 6.8 mm) compared with the ibuprofen group (7 +/- 1.9 mm). CONCLUSIONS: These results suggest that wide variability in gene expression and functional polymorphisms in PTGS2 may explain part of the interindividual variations in acute pain and the analgesic efficacy of nonsteroidal anti-inflammatory drugs and selective COX-2 inhibitors; this may be useful to define individual responders on the basis of genetic variations to predict patient risk and benefit to drugs.

Balancing efficacy and safety in the use of oral sedation in dental outpatients.

BACKGROUND: Concerns about the safety of pediatric oral sedation and the incremental use of triazolam in adults prompted a workshop cosponsored by several professional organizations. OVERVIEW: There is a strong need and demand for adult and pediatric sedation services. Using oral medication to achieve anxiolysis in adults appears to have a wide margin of safety. Mortality and serious morbidity, however, have been reported with oral conscious sedation, especially in young children. Most serious adverse events are related to potentially avoidable respiratory complications. CONCLUSIONS: Clinical trials are needed to evaluate oral sedative drugs and combinations, as well as to develop discharge criteria with objective quantifiable measures of home readiness. Courses devoted to airway management should be developed for dentists who provide conscious sedation services. State regulation of enteral administration of sedatives to achieve conscious sedation is needed to ensure safety. PRACTICE IMPLICATIONS: Safety in outpatient sedation is of paramount concern, with enteral administration of benzodiazepines appearing safe but poorly documented in the office setting. Conscious sedation by the enteral route, including incremental triazolam, necessitates careful patient evaluation, monitoring, documentation, facilities, equipment and personnel as described in American Dental Association and American Academy of Pediatric Dentistry guidelines.

Proposed Guideline Revisions for Dental Sedation and General Anesthesia: Why Target the Safest Level of Sedation?

Recently proposed revisions to the American Dental Association's Guidelines for the Use of Sedation and General Anesthesia by Dentists, aimed at improving safety in dental offices, differentiate between levels of sedation based on drug-induced changes in physiologic and behavioral states. However, the author of this op-ed is concerned the proposed revisions may have far-reaching and unintended consequences.

Prescribing Opioid Analgesics for Acute Dental Pain: Time to Change Clinical Practices in Response to Evidence and Misperceptions.

As the nation comes to terms with a prescription opioid epidemic, dentistry is beginning to understand its own unintentional contribution and seek ways to address it. The article urges dental providers to reexamine entrenched prescribing habits and thought patterns regarding treatment of acute dental pain. It points to evidence suggesting that nonsteroidal anti-inflammatory drugs are nonaddictive and usually more effective for managing many cases of acute dental pain. The authors provide therapeutic recommendations to help dental providers change prescribing patterns.

Research design considerations for single-dose analgesic clinical trials in acute pain: IMMPACT recommendations.

This article summarizes the results of a meeting convened by the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) on key considerations and best practices governing the design of acute pain clinical trials. We discuss the role of early phase clinical trials, including pharmacokinetic-pharmacodynamic (PK-PD) trials, and the value of including both placebo and active standards of comparison in acute pain trials. This article focuses on single-dose and short-duration trials with emphasis on the perioperative and study design factors that influence assay sensitivity. Recommendations are presented on assessment measures, study designs, and operational factors. Although most of the methodological advances have come from studies of postoperative pain after dental impaction, bunionectomy, and other surgeries, the design considerations discussed are applicable to many other acute pain studies conducted in different settings.