Effects of injury and inflammation on pulpal and periapical nerves

Systemic Corticosteroid Uses in Endodontics-Part 2: Enhancing the Success of Local Anesthesia

INTRODUCTION

Chronic inflammation in irreversible pulpitis leads to heightened sensitivity of nociceptive receptors, resulting in persistent hyperalgesia. This poses significant challenges in achieving effective anesthesia for patients with irreversible pulpitis. Various anesthetic techniques and pharmacological approaches have been employed to enhance the success of local anesthesia. Recently, the preemptive use of anti-inflammatory agents, specifically corticosteroids, has gained attention and shown promising results in randomized controlled trials. This systemic review and meta-analysis aimed to evaluate the impact of systemically administered corticosteroids on enhancing anesthetic success in patients undergoing endodontic treatment.

METHODS

A comprehensive search was conducted across multiple databases including PubMed, Cochrane Library, Embase, Scopus, Dentistry & Oral Science, and ProQuest. Additionally, the references of primary studies and related systematic reviews were manually searched for additional relevant publications. The primary outcome assessed was the success of anesthesia, and the effect measure was risk ratio using the random-effects inverse variance method. Statistical significance was set at P < .05. The certainty of the evidence was evaluated using the Grading of Recommendations, Assessment, Development, and Evaluation approach.

RESULTS

Twelve studies involving 917 participants were analyzed to determine the frequency of successful anesthesia. The corticosteroid group demonstrated a significantly higher number of patients achieving successful anesthesia (risk ratio = 1.66; 95% confidence interval, 1.34-2.06;P < .00001). However, heterogeneity within the pooled data analysis was observed (I2 = 57%, P = .007).

CONCLUSIONS

Moderate certainty evidence indicates that preemptive use of systemic corticosteroids enhances the success of local anesthesia, specifically inferior alveolar nerve block, in cases of irreversible pulpitis.

Systemic Corticosteroid Uses in Endodontics-Part 1: Managing Postoperative Pain

INTRODUCTION

This study aimed to systematically search and review all available literature regarding systemic (oral or locally injected) corticosteroids in endodontics to assess their effect on postoperative pain.

METHODS

A search was conducted using PubMed, Cochrane Library, Embase, Scopus, Dentistry & Oral Science, and ProQuest. Randomized controlled trials enrolling participants undergoing endodontic treatment and assessing the presence of pain and pain scores at 6, 12, and 24 hours postoperatively were included. We synthesize the effect measures using risk ratios (RRs), standardized mean differences (SMDs), and their corresponding 95% confidence intervals (CIs). Meta-analysis was performed using the random-effects inverse variance method. The level of significance was set at P < .05. The certainty of the evidence was evaluated using Grading of Recommendations, Assessment, Development and Evaluation approach.

RESULTS

A total of 2303 participants from 29 trials were included. Patients who received corticosteroids were significantly less likely to report pain at 6 hours (RR = 2.5; 95% CI, 1.74-3.61; P < .00001), 12 hours (RR = 2.10; 95% CI, 1.53-2.90; P < .00001), and 24 hours (RR = 1.77; 95% CI, 1.38-2.28; P < .00001) postoperatively. Furthermore, they reported lower pain intensity at 6 hours (SMD = - 0.82; 95% CI, -1.17 to -0.48; P < .00001), 12 hours (SMD = - 0.63; 95% CI, -0.75 to -0.51; P < .00001), and 24 hours (SMD = - 0.68; 95% CI, -0.90 to -0.46; P < .00001) postoperatively.

CONCLUSIONS

Moderate certainty evidence indicates that the use of systemic corticosteroids likely results in a moderate to large reduction in postoperative endodontic pain.

Effect of submucosal cryotherapy compared with steroids and NSAIDs injections on Substance P and Interleukin 6 pulpal release in experimentally induced pulpal inflammation in rabbits

OBJECTIVE

To compare the effect of submucosal cryotherapy using cold saline to dexamethasone sodium phosphate and diclofenac sodium injections on substance P and interleukin 6 release in experimentally induced pulpal inflammation in rabbits' molar teeth.

METHODOLOGY

Fifteen rabbits were randomly classified into 3 groups according to the submucosal injection given: cold saline, dexamethasone sodium phosphate, and diclofenac sodium. A split-mouth design was adopted, the right mandibular molars were experimental, and the left molars served as the control without injections. Intentional pulp exposures were created and left for 6 hours to induce pulpitis. Pulpal tissue was extracted and examined for SP and IL-6 levels using ELISA. Within each group, the level of cytokines released was measured for both control and experimental groups for intragroup comparison to determine the effect of injection. The percentage reduction of each mediator was calculated compared with the control side for intergroup comparison then the correlation between SP and IL-6 levels was analyzed using Spearman's rank order correlation coefficient. Statistical analysis was performed, and the significance level was set at p<0.05.

RESULTS

Submucosal cryotherapy, dexamethasone sodium phosphate, and diclofenac sodium significantly reduced SP and IL-6 pulpal release. Submucosal cryotherapy significantly reduced SP more than and IL-6 more than dexamethasone sodium phosphate and diclofenac sodium. Pulpal reduction of SP and IL-6 showed a strong positive significant correlation.

CONCLUSIONS

Submucosal cryotherapy reduces the pulpal release of SP and IL-6 and could be tested as an alternative to premedication to potentiate the effect of anesthesia and control postoperative endodontic pain.

Morphology of pulpal mineralizations: A scoping review

OBJECTIVE

The aim of this scoping review was to summarize and discuss the morphological features and associated factors of pulpal mineralizations (PMs) as described within the literature.

DATA

The study protocol was registered on the Open Science Framework platform and is available at the following link: https://osf.io/hfqwe. This scoping review was developed according to the PRISMA-ScR guidelines.

SOURCES

A literature search of four electronic databases was performed in SCOPUS, MEDLINE (PubMed), EMBASE and Word of Science, with the last search on May 29, 2023. Study selection was completed by two reviewers independently. Data was extracted regarding study characteristics, types, and features of PM and associated factors.

STUDY SELECTION

Of 1016 studies initially identified ten which qualified were included in this scoping review. Systemic and local factors that result in pulpal insult can contribute to the development of PMs. Three forms of PM have been reported, pulp stones, diffuse mineralizations, and mineralized ectopic connective tissue, with discrete and diffuse mineralization being the two clinically relevant forms. The different forms of PMs exhibit dissimilar morphological features.

CONCLUSION

Pulpal mineralizations exist in two clinically relevant forms: diffuse and discrete mineralizations and are likely associated with a pulpal insult.

CLINICAL SIGNIFICANCE

Understanding the morphology of dental pulp mineralization is the first step to expanding the knowledge of pulp mineralization and could result in improved diagnosis of endodontic pathosis.

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.

Local Anesthesia Onset and Pain Perception in Hemophilic and Thalassemic Conditions

The study aims to evaluate and compare the onset of local anesthesia (LA) and pain perception during endodontic treatment in hemophilic and thalassemic patients. Methods: The study included 90 patients with symptomatic irreversible pulpitis of the mandibular molars. Three groups (n = 30 in each group) were included. Group 1: hemophilic patients; group 2: thalassemic patients; and group 3: individuals without any systemic diseases. Onset of LA and visual analogue scale (VAS) scores was recorded immediately after the administration of local anesthesia, during the pulp exposure procedure, and during canal instrumentation, and were compared between the three groups. Frequency distribution, ANOVA, and linear regression analysis (p < 0.05) were applied. Results: The mean onset time was 46 ± 34 s in the hemophilic group, 42 ± 23 s in the thalassemic group, and 38 ± 12 s in controls, but the differences were statistically insignificant. After LA administration (LA-VAS), all three groups experienced a statistically significant reduction in pain (p = 0.048). On pulp exposure (PE-VAS) (p = 0.82) and during canal instrumentation (CI-VAS) (p = 0.55), there was no statistically significant difference in pain perception between the groups. The coefficients indicate a positive correlation between the VAS and onset time, indicating a positive reduction in the VAS following the administration of LA. Conclusions: Hemophilic patients exhibited a clinically longer average onset time for LA. However, the difference among the three groups with regard to the overall pain perception after LA administration, during and after pulp exposure, and during canal instrumentation was statistically insignificant.

Locus Coeruleus Dysfunction and Trigeminal Mesencephalic Nucleus Degeneration: A Cue for Periodontal Infection Mediated Damage in Alzheimer's Disease?

Alzheimer's disease (AD) is a leading neurodegenerative disease with deteriorating cognition as its main clinical sign. In addition to the clinical history, it is characterized by the presence of two neuropathological hallmark lesions; amyloid-beta (Aβ) and neurofibrillary tangles (NFTs), identified in the brain at post-mortem in specific anatomical areas. Recently, it was discovered that NFTs occur initially in the subcortical nuclei, such as the locus coeruleus in the pons, and are said to spread from there to the cerebral cortices and the hippocampus. This contrasts with the prior acceptance of their neuropathology in the enthorinal cortex and the hippocampus. The Braak staging system places the accumulation of phosphorylated tau (p-tau) binding to NFTs in the locus coeruleus and other subcortical nuclei to precede stages I-IV. The locus coeruleus plays diverse psychological and physiological roles within the human body including rapid eye movement sleep disorder, schizophrenia, anxiety, and depression, regulation of sleep-wake cycles, attention, memory, mood, and behavior, which correlates with AD clinical behavior. In addition, the locus coeruleus regulates cardiovascular, respiratory, and gastrointestinal activities, which have only recently been associated with AD by modern day research enabling the wider understanding of AD development via comorbidities and microbial dysbiosis. The focus of this narrative review is to explore the modes of neurodegeneration taking place in the locus coeruleus during the natural aging process of the trigeminal nerve connections from the teeth and microbial dysbiosis, and to postulate a pathogenetic mechanism due to periodontal damage and/or infection focused on Treponema denticola.

Trigeminal neurons control immune-bone cell interaction and metabolism in apical periodontitis

Abstract

Apical periodontitis (AP) is an inflammatory disease occurring following tooth infection with distinct osteolytic activity. Despite increasing evidence that sensory neurons participate in regulation of non-neuronal cells, their role in the development of AP is largely unknown. We hypothesized that trigeminal ganglia (TG) Nav1.8⁺ nociceptors regulate bone metabolism changes in response to AP. A selective ablation of nociceptive neurons in Nav1.8^Cre/Diphtheria toxin A (DTA)^Lox mouse line was used to evaluate the development and progression of AP using murine model of infection-induced AP. Ablation of Nav1.8⁺ nociceptors had earlier progression of AP with larger osteolytic lesions. Immunohistochemical and RNAscope analyses demonstrated greater number of macrophages, T-cells, osteoclast and osteoblast precursors and an increased RANKL:OPG ratio at earlier time points among Nav1.8^Cre/ DTA^Lox mice. There was an increased expression of IL-1α and IL-6 within lesions of nociceptor-ablated mice. Further, co-culture experiments demonstrated that TG neurons promoted osteoblast mineralization and inhibited osteoclastic function. The findings suggest that TG Nav1.8⁺ neurons contribute to modulation of the AP development by delaying the influx of immune cells, promoting osteoblastic differentiation, and decreasing osteoclastic activities. This newly uncovered mechanism could become a therapeutic strategy for the treatment of AP and minimize the persistence of osteolytic lesions in refractory cases.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s00018-022-04335-w.

A critical analysis of research methods and experimental models to study pulpitis

Pulpitis is the inflammatory response of the dental pulp to a tooth insult, whether it is microbial, chemical, or physical in origin. It is traditionally referred to as reversible or irreversible, a classification for therapeutic purposes that determines the capability of the pulp to heal. Recently, new knowledge about dental pulp physiopathology led to orientate therapeutics towards more frequent preservation of pulp vitality. However, full adoption of these vital pulp therapies by dental practitioners will be achieved only following better understanding of cell and tissue mechanisms involved in pulpitis. The current narrative review aimed to discuss the contribution of the most significant experimental models developed to study pulpitis. Traditionally, in vitro two(2D)- or three(3D)-dimensional cell cultures or in vivo animal models were used to analyse the pulp response to pulpitis inducers at cell, tissue or organ level. In vitro 2D cell cultures were mainly used to decipher the specific roles of key actors of pulp inflammation such as bacterial by-products, pro-inflammatory cytokines, odontoblasts or pulp stem cells. However, these simple models did not reproduce the 3D organisation of the pulp tissue and, with rare exceptions, did not consider interactions between resident cell types. In vitro tissue/organ-based models were developed to better reflect the complexity of the pulp structure. Their major disadvantage is that they did not allow the analysis of blood supply and innervation participation. On the contrary, in vivo models have allowed researchers to identify key immune, vascular and nervous actors of pulpitis and to understand their function and interplay in the inflamed pulp. However, inflammation was mainly induced by iatrogenic dentine drilling associated with simple pulp exposure to the oral environment or stimulation by individual bacterial by-products for short periods. Clearly, these models did not reflect the long and progressive development of dental caries. Lastly, the substantial diversity of the existing models makes experimental data extrapolation to the clinical situation complicated. Therefore, improvement in the design and standardization of future models, for example by using novel molecular biomarkers, databased models and artificial intelligence, will be an essential step in building an incremental knowledge of pulpitis in the future.

Tooth Structure and Replacement of the Triassic Keichousaurus (Sauropterygia, Reptilia) From South China

The small-sized sauropterygian Keichousaurus hui was one of the most abundant marine reptiles from the Triassic Yangtze Sea in South China. Although Keichousaurus has been studied in many aspects, including the osteology, ontogeny, sexual dimorphism, and reproduction, the dentition of this marine reptile was only briefly described in external morphology. In this study, we provide new information on Keichousaurus tooth implantation, histology, and replacement based on a detailed examination of well-preserved specimens collected in the past decades. The tooth histology has been investigated for the first time by analyzing cross-sections of premaxillary teeth and the tooth attachment and implantation have been further revealed by X-ray computed microtomography. We refer the tooth replacement of Keichousaurus to the iguanid replacement type on the basis of the observed invasion of small replacement tooth into the pulp cavity of the functional tooth. Given the resemblance to other extinct and modern piscivorous predators in the morphology and structure of teeth, Keichousaurus might mainly feed on small or juvenile fishes and some relatively soft-bodied invertebrates (e.g., mysidacean shrimps) from the same ecosystem.

Articaine in dentistry: an overview of the evidence and meta-analysis of the latest randomised controlled trials on articaine safety and efficacy compared to lidocaine for routine dental treatment

OBJECTIVES

To comprehensively review the existing studies of articaine in dentistry and conduct a systematic review and meta-analysis to answer the following Population, Intervention, Comparison and Outcome question: "Is articaine a safe and efficacious local anaesthetic for routine dental treatment compared to lidocaine?"

METHODS

Database searches were conducted in Medline Ovid, Medline Pubmed, Scopus, Emcare, Proquest and the Cochrane Central register of Controlled Trials. Inclusion criteria were all existing English, human, randomised controlled trials of interventions involving 4% articaine and 2% lidocaine in routine dental treatment. Twelve studies were included for meta-analysis using Cochrane Review Manager 5 software. Anaesthetic success odds ratios were calculated using a random-effects model.

RESULTS

Articaine had a higher likelihood of achieving anaesthetic success than lidocaine overall and in all subgroup analyses with varying degrees of significance. Overall (OR: 2.17, 95% CI: 1.50, 3.15, I² = 62%) articaine had 2.17 times the likelihood of anaesthetic success of lidocaine (P < 0.0001). For mandibular blocks (OR: 1.50, 95% CI: 1.14, 1.98, I² = 0%) articaine had 1.5 times the likelihood of anaesthetic success of lidocaine (P = 0.004). For all infiltrations, maxillary and mandibular (OR: 2.78, 95% CI: 1.61, 4.79, I² = 66%) articaine had 2.78 times the likelihood of anaesthetic success of lidocaine (P = 0.0002). None of the studies reported any major local anaesthetic-related adverse effects as a result of the interventions.

CONCLUSIONS

Articaine is a safe and efficacious local anaesthetic for all routine dental procedures in patients of all ages, and more likely to achieve successful anaesthesia than lidocaine in routine dental treatment. Neither anaesthetic has a higher association with anaesthetic-related adverse effects.

Postanesthetic Cold Sensibility Test as an Indicator for the Efficacy of Inferior Alveolar Nerve Block in Patients with Symptomatic Irreversible Pulpitis of Mandibular Molars

Materials and Methods

This study was conducted on the mandibular first molars of 54 patients (35 males and 19 females) with signs and symptoms of SIP. To anesthetize the affected molars, all patients received a single carpule of 2% lidocaine with 1 : 100000 epinephrine using a standardized inferior alveolar nerve block (IANB) technique. The cold test was conducted before beginning the endodontic procedures and after gaining lip numbness, and the results were reported as either positive or negative response. The root canal preparation (RCP) was then initiated and the patients' responses were documented (Gold standard test). True pulpal anesthetic failure was described as a pain perception during the access cavity and pulp tissue removal. True pulpal anesthesia was defined as no pain or discomfort during the access cavity and pulp extirpation. The qualitative variables frequencies and percentages of patients with true/false positive and negative responses were determined and then compared using the Chi-square test. The pain perception of male and female patients during the cold test and gold standard was compared using the Fisher exact test. The following diagnostic parameters were calculated using an online statistical calculator: sensitivity, specificity, predictive values, accuracy, and Youden index. In addition, a receiver operating characteristic curve (ROC) was constructed and the area under the curve (AUC) was calculated.

Results

The overall percentage of actual failure of pupal anesthesia was 57%. The sensitivity, specificity, positive predictive value, negative predictive value, accuracy, and Youden index for the cold test were 0.87, 0.91, 0.93, 0.84, 0.89, and 0.78, respectively. There was no statistically significant difference between male and female patients regarding their responses to cold testing and the gold standard test (P > 0.05). Besides, the patients' reactions to the cold test were significantly matched with their reactions to the gold standard test (P < 0.05). The area under the ROC was mostly 0.9.

Conclusion

The cold test could be a valuable and accurate method for predicting the potential pupal anesthesia before beginning the endodontic treatment of mandibular molars with symptomatic irreversible pulpitis, particularly after obtaining postanesthetic soft tissue numbness.

Proteomic analysis of human dental pulp in different clinical diagnosis

OBJECTIVES

The present study aimed to identify proteins obtained from pulp tissue and correlate with each clinical diagnosis (healthy pulp, inflamed pulp, and necrotic pulp).

MATERIALS AND METHODS

A total of forty-five molars were used. Three biological replicas were evaluated. Lysis and sonication were used for protein extraction. Protein quantification was assessed by using the Bradford technique, and shotgun proteome analysis was performed by nanoUPLC-MS^E using a Synapt G2 mass spectrometer. Mass spectra data were processed using the Waters PLGS software, and protein identification was done using the human Uniprot database appended to the PLGS search engine.

RESULTS

A total of 123 different proteins were identified in all evaluated pulp conditions. Among these, 66 proteins were observed for healthy pulp, 66 for inflamed pulp, and 91 for necrotic pulp. Most protein identification was related to immune response, multi-organism process, platelet activation, and stress in inflamed pulp samples compared to healthy pulp. Proteins related to cellular component organization or biogenesis, developmental process, growth, immune response, multi-organism process, response to stimulus, signaling, stress, and transport were identified in cases of apical periodontitis compared to inflamed pulp.

CONCLUSIONS

The progression of the disease to inflamed pulp promoted a high abundance of proteins related to the immune system and stress. Comparing the necrotic pulp with inflamed pulp conditions, a high abundance of proteins was noticed related to metabolism, transport, and response between organisms.

CLINICAL RELEVANCE

This finding may assist in future studies of new markers, understanding of tissue engineering, and development of future products.

Trigeminal Sensory Neurons and Pulp Regeneration

The pulp-dentin complex is innervated by a high density of trigeminal neurons free nerve endings. These neuronal fibers are highly specialized to sense noxious stimuli such as thermal, mechanical, chemical, and biological cues. This robust alert system provides immediate feedback of potential or actual injury triggering reflex responses that protect the teeth from further injury. In the case of patients, pain is the most important experience that leads them to seek oral health care. The adequate removal of the etiology, such as caries, provides ample opportunity for the robust reparative and regenerative potential of the pulp-dentin complex to restore homeostasis. In addition to this elaborated surveillance system, evidence has accumulated that sensory neuronal fibers can potentially modulate various steps of the reparative and regenerative process through cellular communication processes. These include modulation of immunologic, angiogenic, and mineralization responses. Despite these orchestrated cellular events, the defense of the pulp-dentin complex may be overwhelmed, resulting in pulp necrosis and apical periodontitis. Regenerative endodontic procedures have evolved to restore the once lost function of the pulp-dentin complex. After these procedures, a large subset of successful cases demonstrates a positive response to sensitivity testing, suggesting reinnervation of the canal space. This process is likely mediated through cellular and noncellular release of neurotrophic factors such as brain-derived nerve growth factor. In addition, these newly recruited nerve fibers appear equipped to sense thermal stimuli through nonhydrodynamic mechanisms. Collectively, the significance of innervation in the normal physiology of the pulp-dentin complex and its role in regeneration need to be better appreciated to promote further research in this area that could potentially bring new therapeutic opportunities.

Nerve fiber overgrowth in patients with symptomatic diverticular disease

BACKGROUND

Colonic diverticulosis is a common condition in industrialized countries. Up to 25% of patients with diverticula develop symptoms, a condition termed symptomatic uncomplicated diverticular disease (SUDD). The aim of the present study was to characterize neuroimmune interactions and nerve fiber plasticity in the colonic mucosa of patients with diverticula.

METHODS

Controls, patients with diverticulosis and with SUDD were enrolled in the study. Mucosal biopsies were obtained close to diverticula (diverticular region) and in a normal mucosa (distant site), corresponding to sigmoid and descending colon in the controls. Quantitative immunohistochemistry was used to assess mast cells, T cells, macrophages, nerve fibers, and neuronal outgrowth (growth-associated protein 43, GAP43+fibers).

KEY RESULTS

No difference emerged in mast cells and T cells among the three groups. Macrophages were increased in patients with SUDD and diverticulosis as compared to controls. Nerve fibers were enhanced in patients with SUDD and diverticulosis in comparison with controls in the diverticular region. GAP43+ fibers were increased only in patients with SUDD as compared to controls and to patients with diverticulosis in the diverticular region. In patients with SUDD, GAP43 density was increased in the diverticular region compared to distant site. Macrophages close to GAP43+ fibers were increased in the diverticular region of patients with SUDD. Significant correlations were found between GAP43+ fibers and immune cells.

CONCLUSIONS AND INFERENCES

Patients with diverticula are characterized by increased macrophage counts, while nerve fiber sprouting is increased only in the diverticular region of patients with SUDD suggesting a role in symptom generation.

In vitro assessment of interaction between lidocaine hydrochloride and sodium hypochlorite on root canal dentin before and after chemomechanical instrumentation procedures

Introduction

To investigate the effect of resultant precipitate formed on interaction between 2% lidocaine hydrochloride with adrenaline (LA) and 2.5% sodium hypochlorite (NaOCl) on root canal dentin before and after chemomechanical preparation, using scanning electron microscopy (SEM).

Methods

Sixty mandibular premolars were decoronated, and the root length was standardized. All specimens were randomly distributed into the following three groups: Group I (control): 2% LA mixed with sterile water without root canal instrumentation, Group II: 2% LA with 2.5% NaOCl and no instrumentation, and Group III: 2% LA with 2.5% NaOCl, followed by mechanical instrumentation with rotary files. Teeth samples were sectioned into three parts, split and SEM analysis of the root canal wall was done at cervical, middle, and apical root thirds.

Results

SEM images revealed patent dentinal tubules with no precipitate occlusion in the control group, whereas there was occlusion of dentinal tubules with a precipitate in all the specimens in Group II and Group III at all the three root levels studied.

Conclusions

The precipitate formed on the interaction between 2% LA solution and 2.5% NaOCl tends to occlude the dentinal tubules at the coronal, middle, and apical root thirds. The chemomechanical rotary instrumentation procedure did not effectively remove the precipitate from all the three levels of the root specimens studied. LA/sterile water group did not result in any precipitate formation on root canal dentin.

Efficacy of Endo-Ice followed by intrapulpal ice application as an adjunct to inferior alveolar nerve block in patients with symptomatic irreversible pulpitis-a randomized controlled trial

OBJECTIVE

The purpose of the present study was to evaluate the effect of Endo-Ice followed by intrapulpal ice application for reducing pain during pulp extirpation in mandibular molars with symptomatic irreversible pulpitis.

MATERIALS AND METHODS

Sixty patients diagnosed with symptomatic irreversible pulpitis participated in the present study. Subjects were randomly allocated to any one of the following groups: control group-inferior alveolar nerve block with lignocaine (2%) adrenaline (1:80000), articaine group-inferior alveolar nerve block with lignocaine (2%) adrenaline (1:80000) + Buccal infiltration with articaine (4%) with adrenaline (1:100000); or cold group-inferior alveolar nerve block with lignocaine (2%) adrenaline (1:80000) + cold application. The outcome assessor measured the level of pain during access opening and pulp extirpation using the visual analogue scale. The anxiety level of the patient was also measured.

RESULTS

During access opening, there was a significant difference in the pain reduction in the articaine group when compared to cold and control group (p value = 0.02). During pulp extirpation, cold group and articaine group showed a significant reduction in pain levels as compared to the control group (p value = 0.001). There was no difference in the pain level during pulp extirpation among the two test arms (articaine and cold) (p value = 0.99). Further, cold significantly reduced the level of anxiety when compared to the articaine or control group (p value = 0.001).

CONCLUSION

Hence, cold is a simple, supplementary technique in reducing pain during pulp extirpation.

CLINICAL RELEVANCE

Application of cold may help in minimizing the fear of additional injection in managing pain during endodontic treatment.

Volume of Anesthetic Agents and IANB Success: A Systematic Review

The aim of this study was to provide an evidence-based answer to the question: "Is 3.6-mL volume of an anesthetic agent more effective than 1.8-mL volume in providing anesthesia for mandibular molars?" Following formulation of research question and keyword selection, a comprehensive search of the following databases was conducted: Cochrane library, PubMed, Scopus, Google Scholar, ProQuest, and Clinicaltrials.gov. Three-phase eligibility appraisal and quality assessment of the studies were carried out by 2 independent reviewers. To reduce clinical heterogeneity, the included studies were divided into 2 groups: studies on healthy teeth and studies on teeth with pulpitis. The data of included studies were statistically combined through meta-analysis using a fixed-effects model. A total of 20,778 records were initially retrieved from the search. Following screening and eligibility assessment, 8 studies met the eligibility criteria and were included for qualitative synthesis. Of those, 5 studies were qualified for meta-analysis. In the irreversible pulpitis group, increasing the volume of anesthetic agent from 1.8 to 3.6 mL significantly increased the success rate of inferior alveolar nerve block (risk ratio = 2.45, 95% CI: 1.67-3.59, p < .001). However, there was insufficient evidence to draw a conclusion regarding healthy teeth.

Outcomes of Direct Pulp Capping by Using Either ProRoot Mineral Trioxide Aggregate or Biodentine in Permanent Teeth with Carious Pulp Exposure in 6- to 18-Year-Old Patients: A Randomized Controlled Trial

INTRODUCTION

This study aimed to compare the success rates of direct pulp capping (DPC) by using either ProRoot Mineral Trioxide Aggregate (MTA) or Biodentine in the cariously exposed permanent teeth of 6- to 18-year-old patients. Gray discoloration was also evaluated.

METHODS

Fifty-nine cariously exposed permanent teeth, including teeth with diagnosis of normal pulp, reversible pulpitis, or irreversible pulpitis, early periapical involvement, and exposure size of up to 2.5 mm, were included. Each patient with only 1 cariously exposed tooth was randomly allocated to DPC with either ProRoot MTA (n = 30) or Biodentine (n = 29). Patients were recalled every 6 months. Clinical and radiographic examinations were used to determine success.

RESULTS

Fifty-five patients (mean age, 10 ± 2 years), 27 treated with ProRoot MTA and 28 with Biodentine, were included in the analysis. At mean follow-up of 18.9 ± 12.9 months, the success rate was 92.6% with ProRoot MTA and 96.4% with Biodentine (P > .05; difference, 4%; 95% confidence interval [CI], -8% to 16%). Biodentine was non-inferior to ProRoot MTA. Failures were distributed equally in all categories of pulpal diagnosis and occurred in teeth with no periapical involvement and small exposures (0.5 mm). The survival probabilities of DPC with ProRoot MTA and Biodentine were 0.92 (95% CI, 0.73-0.98) and 0.96 (95% CI, 0.80-0.99). No significant difference was observed between them (P > .05). Gray discoloration was observed only with ProRoot MTA (55%).

CONCLUSIONS

Biodentine was non-inferior to ProRoot MTA when used as a DPC material for cariously exposed permanent teeth of 6- to 18-year-old patients. However, Biodentine did not cause any gray discoloration in this study.

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.

Incidence of Endodontic Flare-ups and Its Related Factors: A Retrospective Study

Aims and Objectives:

The aim and objective of the study were to determine the incidence of flare-ups during endodontic treatment and to identify the risk factors associated with flare-ups.

Subjects and Methods:

A total of 1725 patients who were treated during the time period of 2009–2014 by the same endodontist were reviewed. Incidence of flare-up, patients' age, gender, status of pulp, tooth position, number of roots, and treatment provided were taken from their dental records. Relationship between these factors and flare-ups was examined. Statistical analysis was done using Pearson Chi-square test and Fisher's exact test.

Results:

A total of 2% incidence of endodontic flare-ups was seen out of 1725 cases. Patient's age, gender, and diagnosis had a significant effect on the development of flare-ups (P < 0.05). Tooth type, position of tooth, number of root canals, number of visits, and treatment modality had no significant effect on flare-up incidence.

Conclusions:

Diagnosis plays an important role in predicting the incidence of flare-ups. Patients in the age group of 40–60 years had a higher risk of developing flare-ups. Women compared to men are more prone to flare-ups.

Modulation of Dental Inflammation by the Sympathetic Nervous System

Recent findings have indicated that immune responses are subjected to modulation by the sympathetic nervous system (SNS). Moreover, the findings show that the SNS inhibits the production of pro-inflammatory cytokines, while stimulating the production of anti-inflammatory cytokines. The present review is an attempt to summarize the current results on how the SNS affects inflammation in dental tissues. In dental tissues, it has been found that the SNS is significant for recruitment of inflammatory cells such as CD 43+ granulocytes. Sympathetic nerves appear to have an inhibitory effect on osteoclasts, odontoclasts, and on IL-1α production. The SNS stimulates reparative dentin production, since reparative dentin formation was reduced after sympathectomy. Sprouting of sympathetic nerve fibers occurs in chronically inflamed dental pulp, and neural imbalance caused by unilateral sympathectomy recruits immunoglobulin-producing cells to the dental pulp. In conclusion, this article presents evidence in support of interactions between the sympathetic nervous system and dental inflammation.

Microbiological Aspects and Inflammatory Response of Pulp Tissue in Traumatic Dental Lesions

Traumatic dental lesions are more frequently found in the pediatric population, with a major involvement, in 80% of the cases, of the superior central incisors. The exposure of the dental pulp leads to major morphological changes in dental tissue, such as discolouring, acute pulp inflammation, chronic inflammation and necrosis. This article reviews the various studies published on the different types of inflammatory response of the pulp tissue following traumatic events, from the microbiological and histological point of view of various techniques.

Calcitonin gene-related peptide is a key factor in the homing of transplanted human MSCs to sites of spinal cord injury

Mesenchymal stem cells (MSCs) can be used to treat many diseases, including spinal cord injury (SCI). Treatment relies mostly on the precise navigation of cells to the injury site for rebuilding the damaged spinal cord. However, the key factors guiding MSCs to the epicenter of SCI remain unknown. Here, we demonstrated that calcitonin gene-related peptide (CGRP), a neural peptide synthesized in spinal cord, can dramatically aid the homing of human umbilical cord mesenchymal stem cells (HUMSCs) in spinal cord-transected SCI rats. First, HUMSCs exhibited chemotactic responses in vitro to CGRP. By time-lapse video analysis, increased chemotactic index (CMI), forward migration index (FMI) and speed contributed to this observed migration. Then, through enzyme immunoassay, higher CGRP concentrations at the lesion site were observed after injury. The release of CGRP directed HUMSCs to the injury site, which was suppressed by CGRP 8-37, a CGRP antagonist. We also verified that the PI3K/Akt and p38MAPK signaling pathways played a critical role in the CGRP-induced chemotactic migration of HUMSCs. Collectively, our data reveal that CGRP is a key chemokine that helps HUMSCs migrate to the lesion site and thereby can be used as a model molecule to study MSCs homing after SCI.

Effect of Oral Premedication on the Efficacy of Inferior Alveolar Nerve Block in Patients with Symptomatic Irreversible Pulpitis: A Prospective, Double-Blind, Randomized Controlled Clinical Trial

INTRODUCTION

It is generally accepted that achieving complete anaesthesia with an Inferior Alveolar Nerve Block (IANB) in mandibular molars with symptomatic irreversible pulpitis is more challenging than for other teeth. Therefore, administration of Non-Steroidal Anti-Inflammatory Agents (NSAIDs) 1 hour prior to anaesthetic administration has been proposed as a means to increase the efficacy of the IANB in such patients.

AIM

The purpose of this prospective, double-blind, randomized clinical trial was to determine the effect of administration of oral premedication with ketorolac (KETO) and diclofenac potassium (DP) on the efficacy of IANB in patients with irreversible pulpitis.

MATERIALS AND METHODS

One hundred and fifty patients with irreversible pulpitis were evaluated preoperatively for pain using Heft Parker visual analogue scale, after which they were randomly divided into three groups. The subjects received identical tablets of ketorolac, diclofenac pottasium or cellulose powder (placebo), 1 hour prior to administration of IANB with 2% lidocaine containing 1:200 000 epinephrine. Lip numbness as well as positive and negative responses to cold test were ascertained. Additionally pain score of each patient was recorded during cavity preparation and root canal instrumentation. Success was defined as the absence of pain or mild pain based on the visual analog scale readings. The data was analysed using One-Way Anova, Post-Hoc Tukey pair wise, Paired T - Test and chi-square test. Trial Registery Number is 4722/2015 for this clinical trial study.

RESULTS

There were no significant differences with respect to age (p =0.098), gender (p = 0.801) and pre-VAS score (DP-KETO p=0.645, PLAC-KETO p =0.964, PLAC-DP p = 0.801) between the three groups. All patients had subjective lip anaesthesia with the IAN blocks. Patients of all the three groups reported a significant decrease in active pain after local anaesthesia (p< 0.05). The post injection VAS Score was least in group 1 (KETO) followed by group II (DP) & maximum in group III (PLACEBO).

CONCLUSION

Oral pre-medication with 10 mg KETO resulted in significantly higher percentage of successful inferior alveolar block in patients with irreversible pulpitis than pre-medication with 50 mg DP & PLAC.

Variation in Location of the Mandibular Foramen/Inferior Alveolar Nerve Complex Given Anatomic Landmarks Using Cone-beam Computed Tomographic Scans

INTRODUCTION

The inferior alveolar nerve (IAN) injection is 1 of the most commonly administered and useful injections in the field of dentistry. Practitioners use intraoral anatomic landmarks, which vary greatly among patients. The objective of this study was to assist practitioners by identifying a range of normal variability within certain landmarks used in delivering IAN anesthesia.

METHODS

A total of 203 randomly selected retrospective cone-beam computed tomographic scans were obtained from the Midwestern University Dental Institute cone-beam computed tomographic database. InVivoDental5.0 volumetric imaging software (Anatomage, San Jose, CA) was used to measure 2 important parameters used in locating the mandibular foramen (MF)/IAN complex: (1) the angle from the contralateral premolar contact area to the MF and (2) the distance above the mandibular occlusal plane to the center of the MF. The variation of these measurements was compared with established reference values and statistically analyzed using a 1-sample t test.

RESULTS

The angle from the contralateral premolar contact area to the MF for the right and left sides was 42.99° and 42.57°, respectively. The angulations varied significantly from the reference value of 45° (P < .001). The minimum height above the mandibular occlusal plane for the right and left sides was 9.85 mm and 9.81 mm, respectively. The heights varied significantly from the minimum reference value of 6 mm but not the maximum reference value of 10 mm (P < .001).

CONCLUSIONS

Orienting the syringe barrel at an angulation slightly less than 45° and significantly higher than 6 mm above the mandibular occlusal plane can aid in successfully administering anesthesia to the MF/IAN complex.

Anesthetic success of supplemental infiltration in mandibular molars with irreversible pulpitis: A systematic review

Aim:

To systematically review the anesthetic success rates of inferior alveolar nerve block (IANB) injection technique alone with that of combination of IANB and supplemental infiltration (SI) technique when used for pulpal anesthesia of mandibular posterior teeth with irreversible pulpitis during endodontic treatment.

Settings and Design:

The study follows a longitudinal study design involving original research.

Materials and Methods:

Electronic databases were systematically searched for randomized controlled clinical studies. Studies were selected by predefined inclusion and exclusion criteria.

Statistical Analysis Used and Result:

The statistical analysis used was based on the results of the original research. All the included studies showed that there is the difference in the values comparing the two techniques, but the data are not statistically significantly different.

Conclusion:

Based on this review, the better anesthetic efficacy of the SI was observed.

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.

Supplemental pulpal anesthesia for mandibular teeth

Clinical pulpal anesthesia is dependent on the interaction of three major factors. (1) the dentist (2) the patient and (3) local anesthesia. Many patients fear endodontic treatment due to a concern about pain. Although pain treatment is well managed in many endodontic patients, there exists a group of patients who do not receive adequate local anesthesia. The purpose of this review article is to discuss the possible reasons for pulpal anesthetic failures and also to focus on the measures for developing effective approaches for the same.

NaV 1.8, but not NaV 1.9, is upregulated in the inflamed dental pulp tissue of human primary teeth

AIM

To investigate alterations in Na(V) 1.8 and Na(V) 1.9 expression within inflamed dental pulp tissue of human primary teeth.

METHODOLOGY

Dental pulp tissue obtained from both normal and inflamed pulps in primary teeth as well as pulps from normal and inflamed permanent teeth was used. The quantity of Na(V) 1.8 and Na(V) 1.9 expression in the dental pulp tissue was investigated using Western blot analysis. General neuron marker (PGP9.5) was used to quantify for neural density, and an increase in metalloproteinase-9 was used to indicate pulpal inflammation in inflamed teeth. Statistically significant differences for each determined parameter between normal and inflamed teeth of both primary and permanent teeth were tested using the Mann-Whitney rank sum test.

RESULTS

There was no significant difference in neural density of normal and inflamed dental pulp tissue, although degrees of inflammation were increased in the inflamed dental pulp of both permanent and primary teeth (P < 0.05). Na(V) 1.8 and Na(V) 1.9 expression in inflamed pulps of permanent teeth increased significantly compared with normal permanent teeth (P < 0.05). However, only Na(V) 1.8 expression was increased significantly in the inflamed dental pulp of primary teeth (P < 0.05).

CONCLUSIONS

Na(V) 1.8 alone may be the therapeutic target for treatment of painful pulpitis in primary teeth.

The pulpal anesthetic efficacy of articaine versus lidocaine in dentistry: a meta-analysis

BACKGROUND

The authors evaluated published evidence from controlled clinical trials regarding the efficacy of two local anesthetic solutions in providing successful pulpal anesthesia.

METHODS

The authors searched MEDLINE and Embase databases to identify peer-reviewed randomized controlled trials in which researchers directly compared articaine and lidocaine local anesthetic solutions in adult participants. They extracted study characteristics and outcomes data as a basis for meta-analysis. They completed subgroup analyses for both infiltration and mandibular inferior alveolar block anesthetic techniques.

RESULTS

Articaine solutions had a probability of achieving anesthetic success superior to that of lidocaine, with an odds ratio of 2.44 (95 percent confidence interval [CI], 1.59-3.76; P < .0001). The greater odds ratio for articaine increased to 3.81 (95 percent CI, 2.71-5.36; P < .00001) when the authors analyzed only infiltration data. There was weaker, but still significant, evidence of articaine's being superior to lidocaine for mandibular block anesthesia, with an odds ratio of 1.57 (95 percent CI, 1.12-2.21; P = .009), and no difference when the authors considered only symptomatic teeth.

CLINICAL IMPLICATIONS

Research evidence supports using articaine versus lidocaine for achieving pulpal anesthesia when the infiltration mode of administration is used. It is premature to recommend articaine for mandibular block anesthesia in cases involving irreversible pulpitis.

Dental pulp neuropathophysiology

Mechanisms of pulpal pathophysiology are complex and the low compliance environment in which the dental pulp is allocated, further enhances the complexity of this process. Although it is known that it involves the interaction of the immune cells, pulpal cells, cytokines, chemokines and multiple neuropeptides but still there are many gaps in our current knowledge. The understanding of the biochemical and molecular pathways involved in the pulpal inflammation is important so that it can be used clinically to keep the dental pulp vital and healthy. It may thus provide an opportunity to develop potentially new treatment modalities for the inflamed dental pulp in future.

Local anesthesia strategies for the patient with a "hot" tooth

Attaining local anesthesia for the treatment of teeth diagnosed with irreversible pulpitis ("hot" tooth) can be a challenge. This article looks at the strategies a dentist can use to help achieve adequate pulpal anesthesia for the patient, thereby eliminating or reducing treatment pain.

Animal models of orofacial pain

Pain is one of the most common reasons for which patients seek dental and medical care. Orofacial pain conditions consist of a wide range of disorders including odontalgia (toothache), temporomandibular disorders, trigeminal neuralgia and others. Most of these conditions are either inflammatory or neuropathic in nature. This chapter provides an overview of the commonly used models to study inflammatory and neuropathic orofacial pain.

Sensory pulpal nerve fibres and trigeminal ganglion neurons express IL-1RI: a potential mechanism for development of inflammatory hyperalgesia

AIM

To localize interleukin-1 receptor type I (IL-1RI) in rat dental pulp and trigeminal ganglion (TG) and to test the hypothesis that pulpal inflammation increases neuronal expression of IL-1RI.

METHODOLOGY

Female Wistar rats were subjected to unilateral pulp exposures in the maxillary and mandibular first molars, whereas the contralateral jaws served as untreated controls. Seven days later the animals were transcardiacally perfused and the jaws and the TGs were removed and prepared for immunohistochemistry. Immunoreactivity for IL-1RI was examined alone (DAB) and together with calcitonin gene-related peptide (CGRP), neuropeptide Y (NPY), CD31 or CD34 by multiple-labelling immunofluorescence. Quantification of IL-1RI-immunoreactive (-IR) cells in the maxillary and mandibular division of the ganglion was performed in parasagittal immunoreacted sections of the right and left TGs. Data were analysed with Mann-Whitney Rank Sum test (P < 0.05).

RESULTS

Interleukin-1 receptor type I was found on sensory (CGRP-IR) and sympathetic (NPY-IR) nerve fibres and on blood vessels (CD31- and CD34-IR) in the dental pulp. It was also localized on sensory neurons and axons in the TG. Pulpal inflammation significantly increased the expression of IL-1RI in the TG (P < 0.001).

CONCLUSIONS

The localization of IL-1RI on sensory nerve fibres and its up-regulation in TG neurons during pulpal inflammation may imply a direct effect of IL-1 in pulpal nociception. The presence of IL-1RI on sympathetic nerve fibres and on blood vessels may indicate a vasoactive role of the same cytokine in the pulp.

Post inflammatory damage to the enteric nervous system in diverticular disease and its relationship to symptoms

Some patients with colonic diverticula suffer recurrent abdominal pain and exhibit visceral hypersensitivity, though the mechanism is unclear. Prior diverticulitis increases the risk of being symptomatic while experimental colitis in animals increases expression of neuropeptides within the enteric nervous system (ENS) which may mediate visceral hypersensitivity. Our aim was to determine the expression of neuropeptides within the ENS in diverticulitis (study 1) and in patients with symptomatic disease (study 2). Study 1 - Nerves in colonic resection specimens with either acute diverticulitis (AD, n = 16) or chronic diverticulitis (CD, n = 16) were assessed for neuropeptide expression recording % area staining with protein gene product (PGP9.5), substance P (SP), neuropeptide K (NPK), pituitary adenylate cyclase activating polypeptide (PACAP), vasoactive intestinal polypeptide (VIP) and galanin. Study 2 - Seventeen symptomatic and 15 asymptomatic patients with colonic diverticula underwent flexible sigmoidoscopy and multiple peridiverticular mucosal biopsies. Study 1- Neural tissue, as assessed by PGP staining was increased to a similar degree in circular muscle in both AD and CD. The CD specimens showed significant increases in the immunoreactivity of SP, NPK and galanin in both mucosal and circular muscle layer compared with controls. Study 2 - Mucosal histology was normal and PGP9.5 staining was similar between groups however patients with symptomatic diverticular disease demonstrated significantly higher levels of SP, NPK, VIP, PACAP and galanin within the mucosal plexus. Patients with symptomatic diverticular disease exhibit increased neuropeptides in mucosal biopsies which may reflect resolved prior inflammation, as it parallels the changes seen in acute and chronic diverticulitis.