The incidence of mechanical allodynia in patients with irreversible pulpitis

Referred pain is associated with greater odontogenic spontaneous pain and a heightened pain sensitivity in patients with symptomatic irreversible pulpitis

BACKGROUND

Symptomatic irreversible pulpitis often results in heightened reactions to thermal stimuli such as pain evoked by a cold stimulus, and spontaneous odontogenic pain (unprovoked pain).

OBJECTIVE

This study primarily compared the clinical manifestations of odontogenic spontaneous pain and pain provoked by cold stimulus specifically focusing on their sensory discriminative characteristics (intensity, duration and quality) between symptomatic irreversible pulpitis patients with and without referred pain.

METHODS

Twenty-three patients with symptomatic irreversible pulpitis with referred pain and 12 patients without referred pain were included in this cross-sectional study. The following outcomes were assessed: odontogenic spontaneous pain and its descriptors; pain evoked by cold stimulus and qualitative sensory testing before and after local anaesthesia; referred pain location; use of analgesic medication; complementary anaesthesia efficacy. T-test, chi-squared and McNemar tests were applied to the data (p < .50).

RESULTS

Patients with referred pain presented a greater odontogenic pain intensity (p < .05) when considered the average of the last 24 h. These patients also showed higher pain rating and pain descriptors (p < .05). Intensity and duration of the pain evoked by cold stimulus in the non-affected contralateral tooth at baseline were higher for patients with referred pain (p < .05).

CONCLUSION

Symptomatic irreversible pulpitis patients with referred pain present greater odontogenic spontaneous pain and a heightened pain sensitivity. Therefore, patients with referred pain seem more complex from a pain severity perspective, supporting the clinical utility of discriminating symptomatic irreversible pulpitis with and without referred pain.

Pulp Survival of Cracked Teeth with Reversible Pulpitis after Orthodontic Banding and Coronal Coverage - A Prospective Cohort Study with One Year Follow Up

INTRODUCTION

The aim of this prospective study was to investigate the 1-year pulp survival of cracked teeth with reversible pulpitis managed with initial stabilization using orthodontic bands, followed by coronal coverage restorations.

METHODS

One-hundred-and-twenty-five patients with a cracked tooth with reversible pulpitis each were recruited. Preoperative patient and tooth data were collected. After definitive pulp diagnoses were determined following an interim period of orthodontic banding, coronal coverage restorations were placed. Cox and logistic regression analyses were used to assess possible prognostic factors and to correlate initial time to pulp stabilization while in orthodontic bands with eventual outcome. Pulp survival was determined using both clinical and radiographic findings.

RESULTS

One-hundred-and-six cracked teeth were followed up at 1 year. Pulp survival based on clinical and radiographic findings was found in 81 teeth (76.4%). Out of 25 failures, 11 (44%) required root canal treatment (RCT) in the orthodontic band stage and 10 (40%) required RCT during the process of or after coronal coverage restorations. Four teeth (16%) had incidental findings of periapical radiolucencies at the 1-year review without clinical symptoms. Teeth requiring RCT were found to have required longer periods in orthodontic bands prior to a definitive pulp diagnosis (P < .05).

CONCLUSION

A step-by-step approach by using orthodontic banding to monitor pulp status may reduce the incidence of RCT required through definitive coronal coverage restorations for cracked teeth with reversible pulpitis.

An Ex-Vivo Model for Investigating Bacterial Extrusion from Infected Root Canals during Masticatory Function

INTRODUCTION

The extrusion of bacteria from infected root canals may lead to increase in symptoms, expansion of periapical lesions, and contribution to systemic diseases. The aim of this study is to investigate a potential proof-of-concept model to study the extent to which bacteria can escape from infected root canals under dynamic loading (simulated chewing).

METHODS

The study was completed in 2 experiments performed at 2 institutions. Biofilms of Streptococcus intermedius in the first experiment and S. intermedius and Actinomyces naeslundii were allowed to grow in root canals of single-rooted extracted teeth for 3 weeks. The roots of the teeth were suspended in a small chamber containing dental transport medium and were mounted on a lower sample holder of a chewing simulator. In the experimental group, simulated chewing cycles equivalent to 1 year of function were conducted, and then bacterial migration was quantified and compared with stationary teeth.

RESULTS

All experimental samples of the loading group revealed bacterial penetration in both experiments. Several of the unloaded samples revealed no bacterial penetration. In the first experiment, a significantly higher number of bacteria were able to escape into the periapex of the loaded group compared with the unloaded group (P = .017). In the second experiment, there was no significant difference between the 2 bacterial species used in the amount of extruded bacteria; however, there was a highly significant effect for occlusal loading (P = .0001).

CONCLUSIONS

The potential for occlusal forces to enhance bacterial extrusion from infected root canals should be further explored.

Understanding painful versus non-painful dental pain in female and male patients: A transcriptomic analysis of human biopsies

Dental pain from apical periodontitis is an infection induced-orofacial pain condition that presents with diversity in pain phenotypes among patients. While 60% of patients with a full-blown disease present with the hallmark symptom of mechanical allodynia, nearly 40% of patients experience no pain. Furthermore, a sexual dichotomy exists, with females exhibiting lower mechanical thresholds under basal and diseased states. Finally, the prevalence of post-treatment pain refractory to commonly used analgesics ranges from 7-19% (∼2 million patients), which warrants a thorough investigation of the cellular changes occurring in different patient cohorts. We, therefore, conducted a transcriptomic assessment of periapical biopsies (peripheral diseased tissue) from patients with persistent apical periodontitis. Surgical biopsies from symptomatic male (SM), asymptomatic male (AM), symptomatic female (SF), and asymptomatic female (AF) patients were collected and processed for bulk RNA sequencing. Using strict selection criteria, our study found several unique differentially regulated genes (DEGs) between symptomatic and asymptomatic patients, as well as novel candidate genes between sexes within the same pain group. Specifically, we found the role of cells of the innate and adaptive immune system in mediating nociception in symptomatic patients and the role of genes involved in tissue homeostasis in potentially inhibiting nociception in asymptomatic patients. Furthermore, sex-related differences appear to be tightly regulated by macrophage activity, its secretome, and/or migration. Collectively, we present, for the first time, a comprehensive assessment of peripherally diseased human tissue after a microbial insult and shed important insights into the regulation of the trigeminal system in female and male patients.

Nociceptor-Macrophage Interactions in Apical Periodontitis: How Biomolecules Link Inflammation with Pain

Periradicular tissues have a rich supply of peripheral afferent neurons, also known as nociceptive neurons, originating from the trigeminal nerve. While their primary function is to relay pain signals to the brain, these are known to be involved in modulating innate and adaptive immunity by initiating neurogenic inflammation (NI). Studies have investigated neuroanatomy and measured the levels of biomolecules such as cytokines and neuropeptides in human saliva, gingival crevicular fluid, or blood/serum samples in apical periodontitis (AP) to validate the possible role of trigeminal nociceptors in inflammation and tissue regeneration. However, the contributions of nociceptors and the mechanisms involved in the neuro-immune interactions in AP are not fully understood. This narrative review addresses the complex biomolecular interactions of trigeminal nociceptors with macrophages, the effector cells of the innate immune system, in the clinical manifestations of AP.

Analgesic Efficacy of Ketoprofen Transdermal Patch versus Ibuprofen Oral Tablet on Postendodontic Pain in Patients with Irreversible Pulpitis: A Randomized Clinical Trial

Materials and Methods

In this randomized clinical trial, 64 patients who had mandibular first and second molars with irreversible pulpitis were randomly divided into two groups (n = 32) by stratified permuted block randomization. The experimental group used 60 mg KTP every 6 hours, and the control group received 400 mg ibuprofen tablets every 6 hours for 1 day. The severity of pain experienced by patients was quantified before and at 2, 4, 8, 12, 24, and 48 hours after endodontic treatment, using the numerical rating scale (NRS). Data were analyzed by using the t-test, Mann-Whitney test, and generalized estimating equation (GEE) (alpha = 0.05).

Results

The pain score was not significantly different between the two groups at the baseline or any other postoperative time point (P > 0.05). The reduction in the pain score was significant in both groups from 2 to 10 hours and 10 to 48 hours, postoperatively (P < 0.001). The interaction effect of time and group was not significant on the postoperative pain score in the abovementioned time intervals, and the pattern of pain reduction was the same over time in both groups (P > 0.05).

Conclusion

Both KTP and ibuprofen effectively decreased postendodontic pain. Considering the comparable pattern of pain reduction, KTP can be used as an alternative to ibuprofen tablets for effective pain control after endodontic treatment of mandibular first and second molars with irreversible pulpitis.

Evaluation of the clinical efficacy of quantitative light-induced fluorescence technology in diagnosing cracked teeth

BACKGROUND

This retrospective study evaluated the clinical efficacy of quantitative light-induced fluorescence (QLF) technology for crack detection and the diagnosis of cracked teeth and assessed the possibility of a quantitative evaluation of cracks using QLF technology.

METHODS

Patients who were clinically diagnosed with cracked teeth over a 1-year period were included. The QLF images of the corresponding symptomatic cracked teeth and asymptomatic contralateral teeth with crack lines were taken with Qraypen C (AIOBIO, Seoul, Korea). Fluorescence loss (ΔF), maximum fluorescence loss (ΔFmax), red fluorescence (ΔR), and maximum red fluorescence (ΔRmax) of the crack line were analyzed. The correlation between these parameters and sex, age, tooth position (1st premolar, 2nd premolar, 1st molar, 2nd molar), spontaneous pain (+/-), percussion test (+/-), cold test (++/+/-), and bite test (+/-) were statistically analyzed.

RESULTS

A total of 66 patients were included. Twenty-four patients had asymptomatic contralateral teeth with apparent crack lines; thus, 90 teeth were analyzed. The crack lines in 84 teeth observed as red fluorescent lines on the QLF images showed ΔR values higher than the cut-off value set by the analysis program used. The patient's age and the ∣ΔF∣ and ΔR values were positively correlated. However, there was no statistically significant difference in the QLF parameters between the same patient's symptomatic tooth and the contralateral tooth.

CONCLUSIONS

QLF technology is a useful assistive diagnostic device for diagnosing cracked teeth.

Characteristics of Cracked teeth with Reversible Pulpitis after Orthodontic Banding - a Prospective Cohort Study

INTRODUCTION

Cracked teeth with reversible pulpitis can be managed with orthodontic bands in the interim before definitive restorations. The aim of this study was to determine short-term outcomes of these teeth following orthodontic band placement. The time taken for definitive pulp diagnoses after orthodontic band placement and associated prognostic factors was also analyzed.

METHODS

One hundred and twenty-five patients with a cracked tooth with reversible pulpitis each were recruited. Pre-operative data including patient and tooth factors were collected. Cracked teeth were banded and reviewed until symptoms resolved before referral for coronal coverage. Kaplan-Meier and Cox analyses were performed to analyze pulp survival of these teeth. Prognostic factors were investigated using Pearson's Chi-Square and Student's T-Test.

RESULTS

One hundred and twenty-two cracked teeth were analyzed. One hundred and thirteen (92.6%) teeth had the pulpitis resolved within two months (Median 40.0; IQR 28-61). The median time taken for progression to irreversible pulpitis or pulp necrosis for teeth that required root canal treatment was three months (Median 90.0; IQR 68-110). No prognostic factors were associated with the resolution of pulpal symptoms. However, higher pre-operative triggered pain scores (p<0.05, HR 1.547) and absence of a distal marginal ridge crack (p<0.05, HR 0.638) were correlated with a longer duration before definitive pulp diagnoses.

CONCLUSION

Following orthodontic band placement, a normal pulp diagnosis was achieved in 92.6% of cracked teeth with pre-operative reversible pulpitis. Definitive pulp diagnoses could be determined in approximately two months. Teeth with higher pre-operative triggered pain scores may require a longer review period.

Treatment of cracked teeth: A comprehensive narrative review

Objectives

The term “cracked tooth” is used to describe an incomplete fracture initiated from the crown and progressing towards a subgingival direction. Despite the high prevalence of cracked teeth and their frequent association with symptoms and pulpal or periapical pathoses, there is still no consensus in the literature with regard to their restorative and endodontic management. Therefore, the aim of this narrative review was to evaluate the most relevant research and provide an up‐to‐date comprehensive overview regarding the treatment of cracked teeth.

Materials and Methods

An electronic literature search was carried out in MEDLINE (via Ovid), Embase (via Ovid), Scopus, and Web of Science as well as several “Grey literature” sources up to February 22nd 2022 using a combination of pre‐specified ‘free‐text' terms (keywords) and “subject headings.” The search process was supplemented by handsearching in relevant dental journals and reference lists. This narrative review focused on clinical follow‐up studies (observational or interventional studies, case series/reports), laboratory studies and systematic reviews written in English language that reported data on treatment of permanent cracked teeth. The selection of relevant studies was carried out by two reviewers (AK and DG) working independently in two consecutive stages: title/abstract screening and full‐text retrieval. Any discrepancies in the study selection were resolved by discussion between the reviewers.

Results

In total, 64 articles were selected for inclusion in this narrative review.

Conclusions

Cracked teeth with normal pulp or reversible pulpitis have exhibited high pulp and tooth survival rates by the provision of direct or indirect composite restorations. Besides, recent data favour monitoring, especially in the absence of symptoms or compromised tooth structure. When endodontic intervention is required, current evidence suggests that along with appropriate restorative management, outcomes of cracked teeth may be comparable to those of non‐cracked root filled teeth.

Molecular Characterization of Irreversible Pulpitis: A Protocol Proposal and Preliminary Data

Introduction

An attempt to determine the association of a large array of inflammatory proteins in pulpitis with precise measurement of clinical signs and symptoms, and to correlate these findings with levels in peripheral blood has not been reported. Such an analysis could serve to identify key clinical findings and potential biomarkers to predict the prognosis of vital pulp therapy. The aim of this study was to undertake a preliminary, proof-of-concept study to correlate the levels of key inflammatory mediators in cariously exposed dental pulp of adults with reversible or irreversible pulpitis, and no apical periodontitis, with a panel of subjective and objective diagnostic clinical findings as well as the status of the pulp upon exposure. Pulpal and peripheral blood inflammatory mediators were also compared.

Methods

Dental pulp and peripheral blood were sampled. The Luminex technology was used to assess the expression of a panel of 45 inflammatory proteins to determine their association with clinical signs and symptoms of reversible or irreversible pulpitis.

Results

Data from three pulpal and three peripheral blood samples were used for the analysis. The correlation of levels of the 45 proteins in the inflamed dental pulp and peripheral blood was 0.87. The pulp had significantly higher levels of these proteins collectively than peripheral blood (t-test, p = 0.047). The following proteins had correlated at a level of ≥0.8 with the duration of pain with cold: MMP-12, MMP-9, RANTES, MIP-2, MCP-1, MMP-2, MMP-1, and P-Selectin. Relatively high correlations (0.5-0.75) were also present between these proteins and presenting pain level.

Conclusions

Several pulpal proteins correlated well with spontaneous and evoked pain parameters. Peripheral blood may not be necessary in future similar studies. Finally, additional data is needed to identify candidate proteins to be investigated as potential markers of truly irreversible pulp inflammation.

Present status and future directions of intracanal medicaments

Two fundamental goals of endodontic treatment are to prevent or treat apical periodontitis. From a predictive perspective, several variables can affect the outcome of root canal treatment. Some of these variables depend on intraoperative factors, which include irrigation technique, size of the apical preparation, use of intracanal medicaments or the number of appointments necessary to complete the treatment. However, the outcome may also be affected by host and microbial factors. The intensity of periradicular bone loss or tissue damage, the presence of preoperative pain and associated conditions such as mechanical allodynia and central sensitization, the anatomical complexity of the apical portion of the canal, and the virulence and longevity of the bacterial infection can all have a profound influence on the outcome. Furthermore, numerous medical conditions have been reported to decrease the capability of the immune system to heal the periapical tissues. It is the clinician's responsibility to analyse these variables and incorporate them into the disinfection strategy to maximize the chances of healing. This narrative review will focus on the present status of intracanal medicaments, the clinical indications for their use and future directions for research.

Pharmacological Management of Acute Endodontic Pain

Pain associated with infections of the tooth pulp and periapical tissues is intense and often the most common reason for patients seeking emergency dental care. Effective management of acute dental pain requires a deep understanding of pain mechanisms, which enables accurate diagnosis and definitive treatment. While drugs are only used as an adjunct to definitive dental treatment, a thorough understanding of their mechanism of action and effectiveness enables clinicians to effectively control intra-operative and post-operative pain and prevent persistent pain. This review describes how pain is detected, processed, and perceived. It also provides information on evidence-based strategies on the use of different classes of drugs to effectively manage endodontic pain.

Preoperative Factors Associated with Anesthesia Failure for Patients Undergoing Nonsurgical Root Canal Therapy: A National Dental Practice-Based Research Network Study

INTRODUCTION

The aim of this study was to identify preoperative factors associated with local anesthesia failure.

METHODS

The National Dental Practice-Based Research Network (www.NationalDentalPBRN.org) data from 534 patients who received a nonsurgical root canal treatment completed in a single appointment were included in this analysis. Three methods for defining anesthesia failure were used: definition 1, patient-reported level of numbness; definition 2, provider-reported quality of anesthesia; and definition 3, provider-reported use of supplemental anesthesia. Fifty-one preoperative factors were investigated and analyzed individually against the overall failure rate for each method, and multivariate generalized estimating equation logistic models were fit with predictors chosen using stepwise model selection to evaluate factors that may interact with each other.

RESULTS

The overall anesthesia failure rates were 5%, 15%, and 30% for definitions 1, 2, and 3, respectively. Provider experience, diabetes, absence of sharp or aching pain, absence of smoking, and a fair expected outcome were associated with anesthesia failure (definition 1). Provider level of training, absence of a sinus tract, bite sensitivity, and stress making the pain worse were associated with anesthesia failure (definition 2). Provider level of training, pain provoked by stimulus, mandibular teeth, teeth with vital pulps, and pain interfering with daily activities were associated with the use of supplemental anesthesia (definition 3).

CONCLUSIONS

With the range of 5%-30% of anesthesia failures, a few common factors across the models assessed were elucidated. Providers with higher levels of training had significantly fewer anesthesia failures. Patient self-reported history of diabetes and preoperative pain-related interference with daily activities were associated with more anesthesia failures. Greater severity of various tooth-related pain characteristics, as a group but not individually, accounted for more anesthesia failures.

Anesthetic efficacy of Gow-Gates versus inferior alveolar nerve block for irreversible pulpitis: a systematic quantitative review

This review aimed to assess and compare the outcomes of the anesthetic efficacy of inferior alveolar nerve block (IANB) and Gow-Gates mandibular nerve block (GGMNB) in patients with symptomatic irreversible pulpitis. A descriptive systematic review of quantitative research was conducted wherein the “Preferred Reporting Items for Systematic Reviews (PRISMA)” was adopted, and the Problem/Patient/Population, Intervention/Indicator, Comparison, Outcome (PICO) criteria were used to structure the research question. A literature search was performed using PubMed/Medline, Cochrane Library, Google Scholar, and Ovid. Selection criteria were applied for populations over nine years of age, of either sex, with irreversible pulpitis, and articles published in English regarding conventional IANB or IANB and Gow-Gates techniques between 2009 and 2019. Prospective randomized clinical trials or randomized controlled trials were included in the review, in which anesthetic efficacy or success was measured. After screening, four articles were included. Three studies were randomized clinical trials, and two were randomized controlled trials. The validity and reliability of the individual studies were examined. There was evidence of the higher efficacy of the GGMNB technique than that of the IANB technique. However, both techniques can be mastered through training.

Survival and prognostic factors of managing cracked teeth with reversible pulpitis: A 1- to 4-year prospective cohort study

AIM

This prospective clinical study evaluated the clinical performance of managing cracked teeth with reversible pulpitis through a combination of internal and external splinting and investigated factors that can affect pulp survival after splinting.

METHODOLOGY

Thirty-four teeth diagnosed with cracks and reversible pulpitis were enrolled and treated with bidirectional crack splinting: 1) immediate splinting with a stainless-steel band, 2) internal splinting with crack line removal and resin filling and 3) external splinting with a temporary crown followed by final crown placement. If the symptoms remained/recurred, root canal treatment was performed. Patients were followed up at 3, 6 and 12 months, then annually thereafter. Kaplan-Meier survival analysis to calculate the survival of the treated teeth and Cox univariate proportional hazards regression model to investigate prognostic factors were performed.

RESULTS

Twenty-nine (97%) teeth were followed up for up to 4 years. The pulp survival rate was 72% after banding and 91% after final crown cementation. No tooth was extracted (100% tooth survival rate). In the univariate Cox proportional hazard test, pain on percussion was the only statistically significant factor (hazard ratio = 11.77). Teeth with pain on percussion at the first visit had a pulp survival rate of 46% during the follow-up period. In comparison, their counterparts without pain had a 94% pulp survival rate.

CONCLUSIONS

Bidirectional splinting successfully managed cracked teeth with reversible pulpitis. Pain on percussion (mechanical allodynia) may be an important factor in deciding whether to attempt root canal treatment on symptomatic cracked teeth. A step-by-step approach with bidirectional crack splinting should be encouraged for a cracked tooth with a vital pulp without mechanical allodynia rather than pre-emptive root canal treatment.

Associations between Pain Severity, Clinical Findings, and Endodontic Disease: A Cross-Sectional Study

INTRODUCTION

Thorough pain assessment and thermal and mechanical testing are the primary diagnostic tools used to assess the status of pulp and periapical tissues in teeth with potential endodontic pathology. This study evaluated predictors of acute odontogenic pain to better understand the relationship between endodontic pain, clinical testing, endodontic disease, and diagnoses.

METHODS

Participants (N = 228) presenting with acute odontogenic pain underwent standardized clinical testing and reported their pain intensity. Univariate and multiple regression analyses were performed to evaluate the predictors of acute endodontic pain. Chi-square tests with Bonferroni adjustments were conducted to measure the frequency of endodontic diagnostic test findings and clinical observations in patients with different pulpal diagnoses.

RESULTS

A negative response to cold stimulation on the causative tooth and percussion hypersensitivity on the healthy adjacent tooth were the strongest predictors of higher levels of acute endodontic pain. Percussion hypersensitivity on the healthy adjacent tooth was present in a quarter of the cohort and was reported with equal frequency in teeth diagnosed with irreversible pulpitis, necrotic pulp, and previously initiated/treated teeth. Although painful percussion on the causative tooth was more frequently reported in teeth diagnosed with necrotic pulp, painful palpation was more frequently reported on teeth diagnosed with previously initiated/treated teeth.

CONCLUSIONS

Percussion hypersensitivity on the healthy adjacent tooth may reveal a lowered pain threshold and heightened pain sensitization. It is also possible that the 2 commonly performed mechanical sensory tests, percussion and palpation hypersensitivity, may detect different aspects of endodontic pathophysiology and pain processing.

Influence of occlusal reduction on pain after endodontic treatment: a systematic review and meta-analysis

The purpose of this systematic review was to analyze the influence of occlusal reduction on the postoperative pain levels after endodontic treatment (instrumentation and obturation of the root canal system). This review followed the PRISMA statement and was registered at PROSPERO (CRD42018107918). Two independent reviewers searched the Lilacs, Cochrane Library, PubMed (Medline), Web of Science, Scopus, Scielo, and ScienceDirect for articles published until April 2021. The research question was, "Does occlusal reduction decrease postoperative pain in endodontically treated teeth?". Only randomized clinical trials were included. The RevMan 5 program was used for meta-analysis, calculating the relative risk (RR) and 95% confidence interval (CI) of the dichotomous outcome (presence or absence of pain). The search strategies retrieved 4114 studies. Twelve studies were included for qualitative analysis and nine for quantitative analysis. The meta-analysis results did not reveal a significant difference in the reduction of postoperative pain levels for endodontic instrumentation at 6, 12, 24, 48 h and for endodontic obturation at 6 or 12 h after occlusal reduction. According to the GRADE tool, the analyzed outcome was classified as having a moderate level of certainty. It is concluded that occlusal reduction does not interfere with postoperative pain levels after endodontic treatment.

Conservative pulp therapy in the management of reversible and irreversible pulpitis

Conservative pulp therapy is an alternative treatment option to tooth removal and root canal treatment in the management of deep caries, traumatic pulp exposures and developmental anomalies. Pulp tissue preservation can extend the long-term survival of teeth through relatively simple restorative procedures. This article aims to update clinicians on the current state of research in materials, techniques and outcomes of vital pulp therapies and provide practical guidelines for their implementation into daily practice.

Influence of Preoperative Mechanical Allodynia on Predicting Postoperative Pain after Root Canal Treatment: A Prospective Clinical Study

INTRODUCTION

Odontogenic pain can manifest as pulpal pain, periapical pain (mechanical allodynia), or both. This study aimed to assess the changes in the intensity of mechanical allodynia (MA) and to identify predictors of postoperative pain after root canal treatment (RCT).

METHODS

In total, 579 consecutive patients who required RCT were enrolled; we included patients with asymptomatic pulpal diagnoses to avoid any effects of preoperative spontaneous pain on postoperative pain and to evaluate MA independently. Using a visual analog scale (VAS), patients separately indicated the intensity of spontaneous pain, tenderness to percussion, and pain on biting; these measurements were performed before treatment (preoperative pain), at the beginning of each visit (postpreparation pain), and daily for 1 week after RCT (postobturation pain). For analytical purposes, patients were subdivided into 2 groups based on the intensity of preoperative MA (none to mild [VAS <4] or moderate to severe [VAS ≥4]) to evaluate changes in MA and predictive factors of moderate to severe postoperative pain. A generalized estimating equation, repeated-measures analysis of variance, and logistic regression analysis were used.

RESULTS

Although the intensity of MA was significantly higher in the moderate to severe group after the initiation of RCT (P < .05), 93% of them experienced alleviation in MA, and 30% of patients in the none to mild group experienced an increase in MA. After adjusting for clinical variables, moderate to severe preoperative MA and the presence of necrotic pulp were significantly correlated with moderate to severe postoperative pain with an odds ratio of 4.107 and 0.286, respectively.

CONCLUSIONS

Moderate to severe preoperative MA was a predictive factor of postoperative pain in patients undergoing RCT.

Role of macrophage-mediated Toll-like receptor 4-interleukin-1R signaling in ectopic tongue pain associated with tooth pulp inflammation

Background

The existence of referred pain and ectopic paresthesia caused by tooth pulp inflammation may make definitive diagnosis difficult and cause misdiagnosis or mistreatment; thus, elucidation of that molecular mechanism is urgent. In the present study, we investigated the mechanisms underlying ectopic pain, especially tongue hyperalgesia, after tooth pulp inflammation.

Methods

A rat model with mandibular first molar tooth pulp exposure was employed. Tooth pulp exposure-induced heat and mechanical-evoked tongue hypersensitivity was measured, and immunohistochemical staining for Iba1, a marker of active macrophages, IL-1β, IL-1 type I receptor (IL-1RΙ), and toll-like receptor 4 in the trigeminal ganglion was performed. In addition, we investigated the effects of injections of liposomal clodronate Clophosome-A (LCCA), a selective macrophage depletion agent, lipopolysaccharide from Rhodobacter sphaeroides (LPS-RS, a toll-like receptor 4 antagonist), IL-1β, or heat shock protein 70 (Hsp70, a selective agonist of toll-like receptor 4), to examine changes in tongue hypersensitivity and in the regulation of IL-1RΙ, toll-like receptor 4, and transient receptor potential vanilloid 1 (TRPV1) biosynthesis.

Results

At day 1 after tooth pulp exposure, obvious tooth pulp inflammation was observed. Tooth pulp exposure-induced heat and mechanical tongue hypersensitivity was observed from days 1 to 3 after tooth pulp exposure. The production of IL-1β in activated macrophages and toll-like receptor 4 and IL-1RΙ expression were significantly increased in trigeminal ganglion neurons innervating the tongue following tooth pulp exposure. Intra-trigeminal ganglion injection of LCCA significantly suppressed tongue hypersensitivity; however, toll-like receptor 4 and IL-1RΙ expression in trigeminal ganglion neurons innervating the tongue was not significantly altered. Intra-trigeminal ganglion injection of LPS-RS significantly suppressed tongue hypersensitivity and reduced IL-1RΙ expression in the trigeminal ganglion neurons innervating the tongue following tooth pulp exposure. Intra-trigeminal ganglion injection of recombinant Hsp70 significantly promoted tongue hypersensitivity and increased IL-1RI expression in trigeminal ganglion neurons innervating the tongue in naive rats. Furthermore, intra-trigeminal ganglion injection of recombinant IL-1β led to tongue hypersensitivity and enhanced TRPV1 expression in trigeminal ganglion neurons innervating the tongue in naive rats.

Conclusions

The present findings suggest that the neuron-macrophage interaction mediated by toll-like receptor 4 and IL-1RI activation in trigeminal ganglion neurons affects the pathogenesis of abnormal tongue pain following tooth pulp inflammation via IL-1RI and TRPV1 signaling in the trigeminal ganglion. Further research may contribute to the establishment of new therapeutic and diagnostic methods.

Effect of Occlusal Adjustment on Postoperative Pain after Root Canal Treatment: A Randomized Clinical Trial

The aim of this prospective, randomized, clinical study was to analyze the influence of occlusal adjustment on the prevalence of postoperative pain after endodontic treatment. Seventy-eight patients, diagnosed with symptomatic irreversible pulpitis with indication for endodontic treatment, were selected to participate in the study. The participants were randomized and divided into two groups: in the occlusal adjustment group (OAG), endodontic treatment was performed with subsequent occlusal adjustment. In the control group (CG), endodontic treatment was performed without occlusal adjustment. Treatments were performed by the same operator. Pain occurrence and intensity were recorded on two scales: the verbal rating scale (VRS) and numerical rating scale (NRS). Pain assessment was carried out by a second examiner, blinded to the experiment, 6, 24 and 72 h after endodontic treatment. Data were analyzed using Mann-Whitney, chi-squared, and Fisher's exact tests. In the occlusal adjustment group, 71.1% reported postoperative pain and 67.5% reported pain in the control group. At the 6-hour assessment, 21 individuals reported pain in the occlusal adjustment group and 24 in the control group (p=0.672). At the 24-hour assessment, 18 and 19 individuals reported pain (p=0.991) and at the 72-hour assessment, 8 and 4 reported pain (p=0.219), respectively. Occlusal adjustment did not influence the prevalence of postoperative pain of endodontically treated teeth with symptomatic irreversible pulpitis.

The effect of pain intensity levels and clinical symptoms on the treatment preferences of patients with endodontically involved teeth: A preliminary cross-sectional study

Purpose:

This study aimed to evaluate the effect of pain intensity levels and clinical symptoms on the treatment preferences of patients with endodontically involved teeth in a local Turkish population.

Subjects and methods:

A total of 30 patients with symptomatic teeth requiring non-surgical root canal treatment were included in the study. The patients’ demographic (age, gender, and education level) and diagnostic data (tooth type, pain intensity, response to percussion and palpation, presence of referred pain, and diagnosis) were analyzed. Data on the patients’ explicit preferences (requested treatment, whether they are willing to accept a proposed extraction, choice of treatment if an anterior tooth was involved, and choice of treatment if the pain was not severe) as well as previous root canal treatment experiences were also analyzed. Pain intensity levels were evaluated using the Visual Analog Scale.

Results:

Pain intensity levels had a significant effect on the treatment requested by the patient (p=0.001). Among the patients who requested extraction upon referral to the clinic, the rate of those who reported that they would not accept extraction if the pain was located in an anterior tooth was significantly lower than that of patients stating that they would refuse (p=0.039). The presence of referred pain also had a significant effect on the requested treatment (p=0.001).

Conclusion:

The intensity of pain and the presence of referred pain influence patients’ treatment preferences.

To Drill or Not to Drill: Management of Endodontic Emergencies and In-Process Patients during the COVID-19 Pandemic

Introduction

Dental professionals are at high risk of contracting coronavirus disease 2019 (COVID-19) infection because of their scope of practice with aerosol-generating procedures. Recommendation by the Centers for Disease Control and Prevention to suspend elective dental procedures and avoid aerosol-generating procedures posed significant challenges in the management of patients presenting with endodontic emergencies and uncertainty of outcomes for endodontic procedures initiated, but not completed, before shutdown. The purpose of this study was to evaluate the success of palliative care on endodontic emergencies during the COVID-19 pandemic and to evaluate the stability of teeth with long-term Ca(OH)₂ placement because of delays in treatment completion.

Methods

Patients presenting for endodontic emergencies during COVID-19 Shelter-in-Place orders received palliative care, including pharmacologic therapy and/or non–aerosol-generating procedural interventions. Part I of the study evaluated the effectiveness of palliative care, and need for aerosol-generating procedures or extractions was quantified. Part II of the study evaluated survivability and rate of adverse events for teeth that received partial or full root canal debridement and placement of calcium hydroxide before shutdown.

Results

Part I: Twenty-one patients presented with endodontic emergencies in 25 teeth during statewide shutdown. At a follow-up rate of 96%, 83% of endodontic emergencies required no further treatment or intervention after palliative care. Part II: Thirty-one teeth had received partial or full root canal debridement before statewide shutdown. Mean time to complete treatment was 13 weeks. At a recall rate of 100%, 77% of teeth did not experience any adverse events due to delays in treatment completion. The most common adverse event was a fractured provisional restoration (13%), followed by painful and/or infectious flare-up (6.4%), which were managed appropriately and therefore seemed successful. Only 1 tooth was fractured and nonrestorable (3%), leading to a failed outcome of tooth extraction. The remaining 4 outcome failures (13%) were due to patient unwillingness to undergo school-mandated COVID testing or patient unwillingness to continue treatment because of perceived risk of COVID infection.

Conclusions

Palliative care for management of endodontic emergencies is a successful option when aerosol-generating procedures are restricted. This treatment approach may be considered in an effort to reduce risk of transmission of COVID-19 infection during subsequent shutdowns. Prolonged Ca(OH)₂ medicament because of COVID-19 related delays in treatment completion appeared to have minimal effect on survival of teeth.

Effect of Diclofenac Potassium Premedication on Postendodontic Pain in Mandibular Molars with Symptomatic Irreversible Pulpitis: A Randomized Placebo-Controlled Double-Blind Trial

INTRODUCTION

The aim of this prospective, randomized, double-blind clinical trial was to evaluate the effect of a preoperative, single, oral dose of diclofenac potassium (DFK) on postoperative pain and rescue analgesic intake in patients with symptomatic irreversible pulpitis in mandibular molars treated in 1 visit.

METHODS

Seventy emergency patients with moderate to severe preoperative pain randomly received either 50 mg DFK or placebo tablets 1 hour before starting endodontic treatment (n = 35 per group). Patients recorded their pain level 6, 12, 24, and 48 hours after treatment on a 170-mm Heft-Parker visual analog scale. The incidence of rescue analgesic intake was also recorded. Outcome data were statistically analyzed using Mann-Whitney U, Friedman, Wilcoxon signed rank, and chi-square tests. Binary logistic regression assessed the association of predisposing factors with postoperative pain. The significance level (α) was set at 0.05.

RESULTS

Of the 70 patients, 68 were analyzed (n = 34 per group). Both groups had similar baseline characteristics (P > .05). DFK showed significantly less pain incidence and intensity than the placebo at 48 hours only (P < .05). A significant decrease occurred from 24 to 48 hours with DFK (P < .05), which was not recorded with the placebo (P > .05). No difference in the incidence of rescue analgesic intake was reported between groups (P > .05). Food intake timing, sex, and rescue analgesic intake were associated with postoperative pain (P < .05).

CONCLUSIONS

Premedication by a single, oral dose of 50 mg DFK could be effective in reducing postendodontic pain at 48 hours after 1-visit endodontic treatment in mandibular molars with symptomatic irreversible pulpitis.

Evoked and spontaneous pain assessment during tooth pulp injury

Injury of the tooth pulp is excruciatingly painful and yet the receptors and neural circuit mechanisms that transmit this form of pain remain poorly defined in both the clinic and preclinical rodent models. Easily quantifiable behavioral assessment in the mouse orofacial area remains a major bottleneck in uncovering molecular mechanisms that govern inflammatory pain in the tooth. In this study we sought to address this problem using the Mouse Grimace Scale and a novel approach to the application of mechanical Von Frey hair stimuli. We use a dental pulp injury model that exposes the pulp to the outside environment, a procedure we have previously shown produces inflammation. Using RNAscope technology, we demonstrate an upregulation of genes that contribute to the pain state in the trigeminal ganglia of injured mice. We found that mice with dental pulp injury have greater Mouse Grimace Scores than sham within 24 hours of injury, suggestive of spontaneous pain. We developed a scoring system of mouse refusal to determine thresholds for mechanical stimulation of the face with Von Frey filaments. This method revealed that mice with a unilateral dental injury develop bilateral mechanical allodynia that is delayed relative to the onset of spontaneous pain. This work demonstrates that tooth pain can be quantified in freely behaving mice using approaches common for other types of pain assessment. Harnessing these assays in the orofacial area during gene manipulation should assist in uncovering mechanisms for tooth pulp inflammatory pain and other forms of trigeminal pain.

Does occlusal reduction reduce post-endodontic pain? A systematic review and meta-analysis

OBJECTIVES

Pain management during endodontic therapy is an important issue in clinical practice. The objective of this systematic review and meta-analysis was to evaluate the efficacy of occlusal reduction to control the post-operative endodontic pain in adults undergoing root canal therapy.

MATERIALS AND METHODS

Electronic database and manual searches of English papers were conducted up to August 2019 to identify randomised placebo-controlled trials. The MeSH terms used were (endodontics OR root canal therapy) AND (postoperative pain) AND (occlusal reduction). The primary outcome measure was the post-operative pain intensity up to 72 hours. Pooled standardised mean differences (SMDs) and 95% confidence intervals (CIs) were calculated using random-effects inverse variance method. The statistical heterogeneity was assessed using the Cochrane Q test. The significance level was set at P < .05.

RESULTS

In total, six randomised controlled trials including 344 participants were included. Our meta-analyses showed that relief of occlusal surface did not significantly reduce the pain intensity scores at 12- (SMD = -0.46; 95% CI = -1.24, 0.30; P = .239), 24- (SMD = -0.17; 95% CI = -0.73, 0.38; P = .533) and 48- (SMD = -0.67; 95% CI = -1.38, 0.03; P = .063) when compared to placebo. However, at 72 hours, patients received intervention showed significant more pain reduction than placebo groups (SMD = -1.07; 95% CI = -1.81, -0.32; P = .005).

CONCLUSION

Based on this meta-analysis, the efficacy of occlusal reduction in post-endodontic pain control for up to 2 days is not supported. However, on day three, it had a positive influence on the control of post-endodontic pain.

Participation of endotoxin in root canal infections: A systematic review and meta-analysis

This systematic review and meta-analysis aimed to evaluate the relationship between endotoxin levels and presence of clinical signs/symptoms and radiographic features in patients with endodontic infection. Electronic searches were performed on Medline/PubMed, Embase, Cochrane Library, Scielo, Science Direct, Web of Knowledge and Scopus databases for identification of relevant studies published up to December 2016. Grey literature was searched in Google Scholar. The selected literature was reviewed independently by two authors. Clinical studies evaluating the levels of endotoxin and the presence of clinical and radiographic features were included in this review. In order to determine the relationship between endotoxin levels and presence of clinical signs/symptoms and radiographic features meta-analyses were performed. Among the 385 articles identified in the initial search, 30 were included for full-text appraisal and only eight studies met the inclusion criteria for this systematic review. Meta-analysis revealed that individuals having teeth with tenderness to percussion (TTP) (P = 0.04; I² 57%) and previous episode of pain (PEP) (P = 0.001; I² 81%) had higher levels of endotoxin than their counterparts. Size of radiographic lesion >2 mm (P = 0.02; I² 68%) and presence of root canal exudation (EX) (P = 0.0007; I² 0%) were associated with higher levels of endotoxin. This systematic review and meta-analyses provided a strong evidence that endotoxin are related with the presence of clinical signs/symptoms and radiographic features in patients with endodontic infection.

Irreversible Pulpitis - A Source of Antibiotic Over-Prescription?

Antibiotic resistance is a growing public health concern. Antibiotics continue to be prescribed by some clinicians to resolve dental pain even though research indicates that antibiotics are not effective for treating conditions such as irreversible pulpitis. The objective of this study was to determine the extent to which current research and evidence around irreversible pulpitis has been translated into dental practice and the gaps in dentists' knowledge. An on-line clinical vignette format survey questionnaire about treatment of irreversible pulpitis was distributed to the members of the Academy of Operative Dentistry and Academy of General Dentistry (US based international dental bodies). Their responses were recorded and evaluated. A total of 403 dentists participated in the survey. Over a third (39.3%) indicated they would prescribe antibiotics for symptomatic irreversible pulpitis in a permanent tooth occurring without any signs of systemic infection. The rest indicated they would not prescribe antibiotics; most of them would prescribe an analgesic combined with pulpectomy. Those who had undertaken advanced education training achieved a significantly higher mean knowledge score compared to those with just a primary dental degree (p=0.011). Similarly, full or part time academicians had a higher mean knowledge score than the clinicians who work only in private practice (p=0.014). Some dentists continue to prescribe antibiotics inappropriately for alleviating pain due to irreversible pulpitis. Antibiotic prescribing practices of dentists with advanced education or academic engagement were better as compared to the other participants. There is clear evidence of antibiotic over-prescribing for irreversible pulpitis which needs to be addressed urgently.

TNF-α differently regulates TRPV2 and TRPV4 channels in human dental pulp cells

AIM

To investigate the influence of tumour necrosis factor (TNF)-α on transient receptor potential channel vanilloid subfamily type 2 (TRPV2) and TRPV4 channels in human dental pulp cells (HDPCs), and explore the potential downstream signalling pathway mediating this process.

METHODOLOGY

Immunofluorescence staining and ratiometric calcium imaging were used to confirm the expression and activation of TRPV2 and TRPV4 channels. Different regulations of 1 and 10 ng mL^-1 as well as short- and long-term TNF-α treatments to TRPV2 and TRPV4 response were examined by RT-qPCR, Western blot analysis, flow cytometry and ratiometric calcium imaging. Functions of TNF receptor (TNFR)1 and p38 MAPK signalling pathways in this process were also detected by respective inhibitors. Immunoelectron microscopy (IEM) was used to examine long-term effect of TNF-α on TRPV2 expression at the subcellular level. Data were analysed statistically with t-test, and one-way analysis of variance was used with the non-parametric Mann-Whitney and Kruskal-Wallis tests. The level of significance was set at P < 0.05.

RESULTS

TRPV2 and TRPV4 channels were activated by respective agonists in HDPCs. Neither TRPV2 nor TRPV4 channels were upregulated by 1 ng mL^-1 TNF-α (P > 0.05). TRPV2, but not TRPV4, was upregulated by 10 ng mL^-1 TNF-α (P < 0.05). Both short- and long-term treatments with 10 ng mL^-1 TNF-α significantly enhanced TRPV2 responses, whereas only short-term treatment of TNF-α increased TRPV4 response (P < 0.05). Moreover, the inhibitors of TNFR and p38 both significantly decreased the TNF-α-induced up-regulation of TRPV channels (P < 0.05). At the subcellular level, prolonged TNF-α treatment significantly increased the functional expression of the TRPV2 channel especially in the nucleus, endoplasmic reticulum and mitochondria.

CONCLUSIONS

Low and high concentrations, as well as short- and long-term TNF-α treatments regulated the activity of TRPV2 and TRPV4 channels in HDPCs differently, and this effect might be mediated by TNFR1 and p38 MAPK signalling pathways. IEM was used to confirm that prolonged TNF-α treatment significantly increased the functional expression of the TRPV2 channel at a subcellular level.

Oral Neuroimmune Network and Mast Cells

Inflammation is a critical process in the oral cavity, especially in gingival inflammation and pulpitis, as seen in periodontitis and decayed tooth structure. Nevertheless, the cellular process involved in oral inflammation is not well delineated. Recent evidence from other organs as well as the mouth suggests that neurogenic inflammation involving mast cells (MCs) may be a critical factor. MCs, best known for their role in allergic reactions, are also involved in immunity and inflammation. They are located at strategic points close to small blood vessels and nerve fibers often containing substance P (SP). The pain models of reversible or irreversible pulpitis simply suggest the complexity of neural-inflammatory interactions within the dental pulp. In the pulp and periapical area, neuropeptides and cytokines modulate vascular responses, increase permeability and leukocyte migration. SP-immunoreactive nerve fibers and TNF-positive MCs were found localized around blood vessels in all samples of periapical granulomas. By generating a profound number of potent mediators, MCs may serve as a link between the immune, endocrine and nervous systems in pulp inflammation. This role has been strengthened by recent evidence of MCs involvement in inflammatory conditions.

Role of Neuron-Glial Interaction Mediated by IL-1β in Ectopic Tooth Pain

Although many reports have demonstrated that ectopic pain develops in the orofacial region following tooth pulp inflammation, which often causes misdiagnosis and inappropriate treatment for patients with pulpitis, the precise mechanism remains unknown. In the present study, we hypothesized that the functional interaction between satellite glial cells and neurons mediated by interleukin 1β (IL-1β) in the trigeminal ganglion (TG) is involved in ectopic orofacial pain associated with tooth pulp inflammation. The digastric muscle electromyogram (D-EMG) activity elicited by capsaicin administration into the maxillary second molar tooth pulp was analyzed to evaluate the noxious reflex and was significantly increased in rats with inflammation of the maxillary first molar (M1) versus rats injected with saline. A significant increase in the expression of connexin43 (Cx43), a gap junction containing protein, was observed in activated satellite glial cells surrounding second molar-innervating neurons in the TG after M1 pulpitis. Daily administration of Gap26, a Cx43 mimetic peptide and inhibitor, in the TG significantly suppressed the enhancement of capsaicin-induced D-EMG activity and the percentage of Fluoro-Gold (FG)-labeled cells encircled by glial fibrillary acid protein-immunoreactive (IR) + Cx43-IR cells after M1 pulp inflammation ( P < 0.01). The percentage of FG-labeled cells encircled by glial fibrillary acid protein-IR + IL-1β-IR cells, IL-1 type I receptor-IR cells labeled with FG, and TRPV1-IR cells labeled with FG significantly increased after M1 pulp inflammation ( P < 0.01). Daily administration of IL-1ra, an IL-1 receptor antagonist, into the TG significantly reduced the enhancement of capsaicin-induced D-EMG activity and the percentage of TRPV1-IR neurons labeled with FG after M1 pulp inflammation ( P < 0.01). The present findings suggest that satellite glial cell is activated in the TG via activated gap junctions composed of Cx43 following tooth pulp inflammation, which leads to the hyperactivation of remote neurons via IL-1β mechanisms and results in ectopic tooth pulp pain in the adjacent tooth.

Unmasking the Effect of Analgesics on Endodontic Diagnosis Using a Novel Bite Force Sensor Device: A Prospective, Randomized Clinical Trial

INTRODUCTION

A definitive diagnosis is of primary importance before initiating any endodontic treatment; yet, there are occasions when the dental professional is unable to accurately reproduce the patient's chief complaint, as it can pose a dilemma and may require consideration of multiple variables in order to reach an accurate diagnosis. So to overcome this problem, a methodical approach in providing endodontic treatment should be implemented which includes diagnosis, definitive dental treatment and adjunctive drug therapy, known as the "3D" strategy.

AIM

The purpose of this study was to evaluate the possible "masking" effect of these analgesics on endodontic diagnosis using a novel bite force sensor device.

MATERIALS AND METHODS

A total of 90 patients with endodontic pain were selected and they were given either a placebo or 400 mg ibuprofen (brufen) or 50mg diclofenac sodium (voveron). Both patients and operators were completely blinded to the drugs administered. Bite force tolerance values were noted before and one hour after administration of medication using the self designed bite force sensor.

RESULTS

The pre- and post-bite force tolerance values were tabulated for both contralateral and affected tooth. For the affected tooth, there was statistically significant difference between pre- and post-bite force tolerance values in Group I (i.e., ibuprofen) and Group II (i.e., diclofenac sodium) (p<0.05) with no significant difference observed in Group III (placebo).

CONCLUSION

The easily available over the counter self administered analgesics in addition to providing symptomatic relief to patients suffering from symptomatic apical periodontitis may also cloud the definitive diagnosis of the clinician, thus jeopardising the treatment plan. The self designed bite force sensor was effective in arriving at a definitive diagnosis in teeth with chronic irreversible pulpitis with symptomatic apical periodontitis, where the allodynia has been camouflaged by the use of analgesics like ibuprofen and diclofenac sodium.

Pain levels and typical symptoms of acute endodontic infections: a prospective, observational study

BACKGROUND

This study aimed to identify key symptoms that could be associated with the diagnosis of acute forms of symptomatic apical periodontitis (SAP) and symptomatic irreversible pulpitis (SIP), and to identify a diagnostic algorithm based on these symptoms.

METHODS

In this prospective, observational study 173 emergency patients diagnosed with acute pain of endodontic origin and no swelling or fistula were included. Patients were asked 11 specific questions from a checklist with a possible discerning value between acute SAP and acute SIP. Pain levels were recorded using the numeric rating scale (NRS-11). Subsequently, the painful tooth was diagnosed. Logistic regression was used to evaluate the checklist regarding its differentiation between SAP (N = 103) and SIP (N = 70). Moreover, a decision tree was constructed based on recursive partitioning to identify a hierarchy in differentiating symptoms.

RESULTS

With identical median NRS-11 scores of 8, the teeth diagnosed with acute SAP and SIP were severely painful. The decision tree analysis resulted in a tree with splits according to pain on cold, perceived tooth extrusion, and pain duration. The overall sensitivity of the tree to detect SAP based on key symptoms was 95 %, its specificity was 31 %.

CONCLUSIONS

The best indicator for SAP was a reported absence of pain to cold stimuli. In teeth that did have a history of pain triggered by cold stimuli, the decision tree correctly identified SAP in 72 % of the teeth that felt too high and had hurt for less than one week.

Dynamic mechanical allodynia following finger amputation: Unexpected skin hyperinnervation

The development of chronic pain after amputations is not an uncommon event. In some cases the most disabling problem is represented by the symptom called dynamic mechanical allodynia, characterized by the painful sensation evoked by gently stroking the skin. Despite the growing interest in understanding pain mechanisms, little is known about the mechanism sustaining this peculiar type of pain. We present here the case of a 53-year-old female patient who complained of severe tactile allodynia in the hand after amputation of her left second finger, resistant to several medical and surgical treatments. In order to gain information about the pain mechanism, two neurodiagnostic skin biopsies were obtained from the area of tactile allodynia and from the contralateral, normal skin area. Skin biopsies showed an unexpected increased innervation of the allodynic skin compared to the contralateral, normal skin area (+ 80.1%). Hyperinnervation has been proposed as a mechanism of pain following nerve lesions, but the increased innervation described here could be also attributed to neuronal plasticity occurring in chronic inflammatory conditions. Independently from the uncertain cause of the epidermal hyperinnervation, in this patient we tried to reduce the elevated number of epidermal nerve fibres by treating the skin with topical capsaicin (0.075%) three times a day, and obtained a persistent pain relief. In conclusion, neurodiagnostic skin biopsy might represent an useful tool for detecting derangements of epidermal innervation in patients with dynamic mechanical allodynia and can help to select an individually tailored therapeutic strategy in such difficult clinical conditions. Further studies are needed to clarify this issue and try to gain better understanding of chronic pain mechanisms in patients who underwent finger amputation.

X-tip intraosseous injection system as a primary anesthesia for irreversible pulpitis of posterior mandibular teeth: A randomized clinical trail

Background:

Successful anesthesia during root canal therapy may be difficult to obtain. Intraosseous injection significantly improves anesthesia's success as a supplemental pulpal anesthesia, particularly in cases of irreversible pulpitis. The aim of this study was to compare the efficacy of X-tip intraosseous injection and inferior alveolar nerve (IAN) block in primary anesthesia for mandibular posterior teeth with irreversible pulpitis.

Materials and Methods:

Forty emergency patients with an irreversible pulpitis of mandibular posterior teeth were randomly assigned to receive either intraosseous injection using the X-tip intraosseous injection system or IAN block as the primary injection method for pulpal anesthesia. Pulpal anesthesia was evaluated using an electric pulp tester and endo ice at 5-min intervals for 15 min. Anesthesia's success or failure rates were recorded and analyzed using SPSS version 12 statistical software. Success or failure rates were compared using a Fisher's exact test, and the time duration for the onset of anesthesia was compared using Mann–Whitney U test. P < 0.05 was considered significant.

Results:

Intraosseous injection system resulted in successful anesthesia in 17 out of 20 patients (85%). Successful anesthesia was achieved with the IAN block in 14 out of 20 patients (70%). However, the difference (15%) was not statistically significant (P = 0.2).

Conclusion:

Considering the relatively expensive armamentarium, probability of penetrator separation, temporary tachycardia, and possibility of damage to root during drilling, the authors do not suggest intraosseous injection as a suitable primary technique.

Temporomandibular joint pain: a critical role for Trpv4 in the trigeminal ganglion

Temporomandibular joint disorder (TMJD) is known for its mastication-associated pain. TMJD is medically relevant because of its prevalence, severity, chronicity, the therapy-refractoriness of its pain, and its largely elusive pathogenesis. Against this background, we sought to investigate the pathogenetic contributions of the calcium-permeable TRPV4 ion channel, robustly expressed in the trigeminal ganglion sensory neurons, to TMJ inflammation and pain behavior. We demonstrate here that TRPV4 is critical for TMJ-inflammation-evoked pain behavior in mice and that trigeminal ganglion pronociceptive changes are TRPV4-dependent. As a quantitative metric, bite force was recorded as evidence of masticatory sensitization, in keeping with human translational studies. In Trpv4(-/-) mice with TMJ inflammation, attenuation of bite force was significantly less than in wildtype (WT) mice. Similar effects were seen with systemic application of a specific TRPV4 inhibitor. TMJ inflammation and mandibular bony changes were apparent after injections of complete Freund adjuvant but were remarkably independent of the Trpv4 genotype. It was intriguing that, as a result of TMJ inflammation, WT mice exhibited significant upregulation of TRPV4 and phosphorylated extracellular-signal-regulated kinase (ERK) in TMJ-innervating trigeminal sensory neurons, which were absent in Trpv4(-/-) mice. Mice with genetically-impaired MEK/ERK phosphorylation in neurons showed resistance to reduction of bite force similar to that of Trpv4(-/-) mice. Thus, TRPV4 is necessary for masticatory sensitization in TMJ inflammation and probably functions upstream of MEK/ERK phosphorylation in trigeminal ganglion sensory neurons in vivo. TRPV4 therefore represents a novel pronociceptive target in TMJ inflammation and should be considered a target of interest in human TMJD.

Oxidized linoleic acid metabolite-cytochrome P450 system (OLAM-CYP) is active in biopsy samples from patients with inflammatory dental pain

Endogenous TRPV1 agonists such as oxidized linoleic acid metabolites (OLAMs) and the enzymes releasing them [eg, cytochrome P450 (CYP)] are up-regulated after inflammation in the rat. However, it is not known whether such agonists are elevated in human inflammatory pain conditions. Because TRPV1 is expressed in human dental pulp nociceptors, we hypothesized that OLAM-CYP machinery is active in this tissue type and is increased under painful inflammatory conditions such as irreversible pulpitis (IP). The aim of this study was to compare CYP expression and linoleic acid (LA) metabolism in normal vs inflamed human dental pulp. Our data showed that exogenous LA metabolism was significantly increased in IP tissues compared to normal tissues and that pretreatment with a CYP inhibitor, ketoconazole, significantly inhibited LA metabolism. Additionally, extracts obtained from LA-treated inflamed tissues evoked significant inward currents in trigeminal ganglia neurons and were blocked by pretreatment with the TRPV1 antagonist IRTX. Moreover, extracts obtained from ketoconazole-pretreated inflamed tissues significantly reduced inward currents in trigeminal ganglia neurons. These data suggest that LA metabolites produced in human inflamed tissues act as TRPV1 agonists and that the metabolite production can be targeted by CYP inhibition. In addition, immunohistochemical analysis of 2 CYP isoforms, CYP2J and CYP3A1, were shown to be predominately expressed in immune cells infiltrating the inflamed dental pulp, emphasizing the paracrine role of CYP enzymes in OLAM regulation. Collectively, our data indicate that the machinery responsible for OLAM production is up-regulated during inflammation and can be targeted to develop potential analgesics for inflammatory-induced dental pain.