Antibodies in normal and diseased pulps reactive with microorganisms isolated from deep caries

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.

Pulp Inflammation Diagnosis from Clinical to Inflammatory Mediators: A Systematic Review

INTRODUCTION

Similar to other tissues, the dental pulp mounts an inflammatory reaction as a way to eliminate pathogens and stimulate repair. Pulp inflammation is prerequisite for dentin pulp complex repair and regeneration; otherwise, chronic disease or pulp necrosis occurs. Evaluation of pulp inflammation severity is necessary to predict the clinical success of maintaining pulp vitality. Clinical limitations to evaluating in situ inflammatory status are well-described. A molecular approach that aids clinical distinction between reversible and irreversible pulpitis could improve the success rate of vital pulp therapy. The aim of this article is to review inflammatory mediator expression in the context of clinical diagnosis.

METHODS

We searched PubMed and Cochrane databases for articles published between 1970 and December 2016. Only published studies of inflammatory mediator expression related to clinical diagnosis were eligible for inclusion and analysis.

RESULTS

Thirty-two articles were analyzed. Two molecular approaches were described by study methods, protein expression analysis and gene expression analysis. Our review indicates that interleukin-8, matrix metalloproteinase 9, tumor necrosis factor-α, and receptor for advanced glycation end products expression increase at both the gene and protein levels during inflammation.

CONCLUSIONS

Clinical irreversible pulpitis is related to specific levels of inflammatory mediator expression. The difference in expression between reversible and irreversible disease is both quantitative and qualitative. On the basis of our analysis, in situ quantification of inflammatory mediators may aid in the clinical distinction between reversible and irreversible pulpitis.

Dental caries and growth in school-age children

BACKGROUND AND OBJECTIVE

Dental caries in young children is commonly untreated and represents a public health problem. Dental caries in children is reported to affect their anthropometric outcomes, but the evidence is conflicting. Some studies found no association, whereas others found that caries was associated with underweight or overweight. The objective was to assess the relationship between dental caries status and height and weight in 6- to 8-year-old Saudi children with high caries prevalence.

METHODS

This study was a cross-sectional survey in schoolchildren aged 6 to 8 years attending military primary schools in Jeddah, Saudi Arabia. Caries status was assessed by using the dmft (decayed, missing, filled, teeth [primary teeth]) index. Height and weight were assessed by using z scores of height-for-age (HAZ), weight-for-age (WAZ), and BMI-for-age (BAZ) calculated by World Health Organization standardized procedures. Relationships between caries and HAZ, WAZ, and BAZ were assessed by using regression models.

RESULTS

A total of 417 of the 436 eligible schoolchildren with complete data were included, with a response rate of 95.6%. Their mean dmft index was 5.7 ± 4.2. There was an inverse linear relationship between caries status and children's HAZ, WAZ, and BAZ and significantly lower anthropometric outcomes for children at each consecutive group with higher levels of caries. The associations remained significant after adjusting for dental, social, and demographic variables.

CONCLUSIONS

The inverse linear association between dental caries and all anthropometric outcomes suggests that higher levels of untreated caries are associated with poorer growth in Saudi schoolchildren.

Impact of treating dental caries on schoolchildren's anthropometric, dental, satisfaction and appetite outcomes: a randomized controlled trial

BACKGROUND

There are no randomized controlled trials to assess the impact of treating dental caries on various aspects of children's health. This study was conducted to assess the impact of dental treatment of severe dental caries on children's weight, height and subjective health related outcomes, namely dental pain, satisfaction with teeth and smile, dental sepsis and child's appetite.

METHODS

The study was a community-based, randomized, controlled trial in schoolchildren aged 6-7 years with untreated dental caries. Participants were randomly assigned to early (test) or regular (control) dental treatment. The primary outcome was Weight-for-age Z-score. Secondary outcomes were Height-for-age and BMI-for-age Z-scores, dental pain, dental sepsis, satisfaction with teeth and child's appetite.

RESULTS

86 children were randomly assigned to test (42 children) and control (44) groups. Mean duration of follow-up was 34.8 (± 1.1) weeks. There were insignificant improvements in anthropometric outcomes between the groups after treatment of caries. However, treated children had significantly less pain experience (P = 0.006) (OR 0.09, [0.01-0.51]) and higher satisfaction with teeth (P = 0.001) (OR 9.91, [2.68-36.51]) compared to controls. Controls had significantly poorer appetites (P = 0.01) (OR 2.9, [1.24-6.82]) compared to treated children. All treated children were free of clinical dental sepsis whereas 20% (9 of 44) of controls who were free of sepsis at baseline had sepsis at follow-up.

CONCLUSIONS

Although dental treatment did not significantly improve the anthropometric outcomes, it significantly improved the dental outcomes and children's satisfaction with teeth, smile and appetite. This is the first study to provide evidence that treatment of severe dental caries can improve children's appetite.

TRIAL REGISTRATION

Effect of Dental Treatment on Children's Growth. Clinical Trial Gov ID# NCT01243866.

The relationship of pulp polyp with the presence and concentration of immunoglobulin E, histamine, interleukin-4 and interleukin-12

The aim of this study was to evaluate the relationship between pulp polyp formation and immunoglobulin E (IgE), histamine and interleukin-4 (IL-4) as the most important mediators which are involved in allergy. Thirty-two samples including 16 pulp polyps and 16 normal pulps were gathered. After homogenising the pulpal tissue samples, enzyme-linked immunosorbent assay (ELISA) techniques were used to assess the concentration of IgE, histamine, IL-4 and IL-12. The two groups showed statistically significant differences in terms of both the concentration and presence of IgE, histamine and IL-4 (P < 0.001); both presence and concentration of IgE, histamine and IL-4 were higher in pulp polyps than in normal pulps. There is not any significant difference between case and control groups regarding IL-12. The results of this study give rise to the possibility of type I hypersensitivity reaction being involved in pulp polyp's pathogenesis.

An overview of the dental pulp: its functions and responses to injury

The dental pulp is a unique tissue and its importance in the long-term prognosis of the tooth is often ignored by clinicians. It is unique in that it resides in a rigid chamber which provides strong mechanical support and protection from the microbial rich oral environment. If this rigid shell loses its structural integrity, the pulp is under the threat of the adverse stimuli from the mouth, such as caries, cracks, fractures and open restoration margins, all of which provide pathways for micro-organisms and their toxins to enter the pulp. The pulp initially responds to irritation by becoming inflamed and, if left untreated, this will progress to pulp necrosis and infection. The inflammation will also spread to the surrounding alveolar bone and cause periapical pathosis. The magnitude of pulp-related problems should not be underestimated since their most serious consequence is oral sepsis, which can be life threatening, and hence correct diagnosis and management are essential. Clinicians must have a thorough understanding of the physiological and pathological features of the dental pulp as well as the biological consequences of treatment interventions.

Effect of systemic penicillin on pain in untreated irreversible pulpitis

OBJECTIVE

The purpose of this prospective, randomized, double-blind study was to determine the effect of penicillin on pain in untreated teeth diagnosed with irreversible pulpitis.

STUDY DESIGN

Forty emergency patients participated, and each had a clinical diagnosis of an irreversible pulpitis. Patients randomly received a 7-day oral dose (28 capsules, 500 mg each, to be taken every 6 hours) of either penicillin or a placebo control in a double-blind manner. No endodontic treatment was performed. Each patient also received ibuprofen; acetaminophen with codeine (30 mg); and a 7-day diary to record pain, percussion pain, and number and type of pain medication taken.

RESULTS

The administration of penicillin did not significantly (P >.05) reduce pain, percussion pain, or the number of analgesic medications taken by patients with untreated irreversible pulpitis. The majority of patients with untreated irreversible pulpitis had significant pain and required analgesics to manage this pain.

CONCLUSION

Penicillin should not be prescribed for untreated irreversible pulpitis because penicillin is ineffective for pain relief.

Current status of a mucosal vaccine against dental caries

The evidence of a specific bacterial cause of dental caries and of the function of the salivary glands as an effector site of the mucosal immune system has provided a scientific basis for the development of a vaccine against this highly prevalent and costly oral disease. Research efforts towards developing an effective and safe caries vaccine have been facilitated by progress in molecular biology, with the cloning and functional characterization of virulence factors from mutans streptococci, the principal causative agent of dental caries, and advancements in mucosal immunology, including the development of sophisticated antigen delivery systems and adjuvants that stimulate the induction of salivary immunoglobulin A antibody responses. Cell-surface fibrillar proteins, which mediate adherence to the salivary pellicle, and glucosyltransferase enzymes, which synthesize adhesive glucans and allow microbial accumulation, are virulence components of mutans streptococci, and primary candidates for a human caries vaccine. Infants, representing the primary target population for a caries vaccine, become mucosally immunocompetent and secrete salivary immunoglobulin A antibodies during the first weeks after birth, whereas mutans streptococci colonize the tooth surfaces at a discrete time period that extends around 26 months of life. Therefore, immunization when infants are about one year old may establish effective immunity against an ensuing colonization attempts by mutans streptococci. The present review critically evaluates recent progress in this field of dental research and attempts to stress the protective potential as well as limitations of caries immunization.

Periapical inflammatory responses and their modulation

Periapical inflammatory responses occur as a consequence of bacterial infection of the dental pulp, as a result of caries, trauma, or iatrogenic insult. Periapical inflammation stimulates the formation of granulomas and cysts, with the destruction of bone. These inflammatory responses are complex and consist of diverse elements. Immediate-type responses--including vasodilatation, increased vascular permeability, and leukocyte extravasation--are mediated by endogenous mediators, including prostanoids, kinins, and neuropeptides. Non-specific immune responses--including polymorphonuclear leukocyte and monocyte migration and activation, and cytokine production--are elicited in response to bacteria and their products. Interleukin-1 and prostaglandins in particular have been implicated as central mediators of periapical bone resorption. Chronic periapical inflammation further involves specific T- and B-cell-mediated anti-bacterial responses, and activates a network of regulatory cytokines which are produced by Th1- and Th2-type T-lymphocytes. Various naturally occurring and genetically engineered models of immunodeficiency are beginning to help elucidate those components of the immune system which protect the pulpal/periapical complex. Both specific and non-specific responses interface with and are regulated by the neural system. The modulation of these responses by immune response modifies, cytokine antagonists, and other novel therapeutic agents is discussed. As an experimental model, periapical inflammation has many advantages which permit it to be used in studies of microbial ecology and pathogenesis, host response, neuroimmunology, and bone resorption and regeneration.

The effects of immunoglobulins on the convective permeability of human dentine in vitro

Immunoglobulin molecules are localized in the dentinal tubules of non-carious and carious teeth, but their possible role in caries invasion is not understood. This study sought to examine the effects of immunoglobulin molecules on dentine permeability using a fluid-filtration method. Crown segments cut from impacted human third molars were treated by filtration with 100 micrograms/ml IgG, 100 micrograms/ml IgA or 30 micrograms/ml IgM under a constant pressure. Flow rates were recorded and percent changes in flow rate analysed over time. Filtrates collected at various times were tested for changes in immunoglobulin concentrations by an enzyme-linked immunosorbent assay, and the percent retention of immunoglobulins to dentine was calculated. There was a decreasing non-linear exponential relation between the percent changes in flow rate and filtration time for all three immunoglobulins. The percentage of retained immunoglobulins was significantly related to the filtration time for all three classes of immunoglobulins. Immunoglobulin retention contributed to significant changes in flow rate with time. These in vitro results indicate the potential mechanism of immunoglobulins in decreasing tabular permeability.

Detection of microbial-derived fatty acids in carious dentin by gas chromatography and gas chromatography-mass spectrometry

The aim of the present study was to analyze the fatty acid content of carious and sound human dentin. Gas chromatography and gas chromatography-mass spectrometry revealed the presence of fatty acids of C10-C18 size in the carious dentin, whereas fatty acids of C16 size were present in minute amounts in three samples of the corresponding sound dentine controls. No fatty acids were detected in the other sound dentin control samples. The source of fatty acids was considered to be microorganisms invading the dentin during the progression of the caries lesion. The presence of bacterial fatty acids in carious dentin may serve as a marker for the pathological process and thus contribute to the understanding of the mechanisms involved.

Quantitative analysis of immunoglobulins and inflammatory factors in human pulpal blood from exposed pulps

The levels of immunoglobulins (IgG, IgA, and IgM) and inflammatory factors (elastase, prostaglandin E2, interleukin-1 alpha, interleukin-1 beta, interleukin-6, and tumor necrosis factor-alpha) in the blood of human dental pulp were quantified, using enzyme-linked immunosorbent assays. The pulpal blood samples were obtained with nylon fiber pellets from normal and inflamed dental pulp at pulp sites exposed on pulpectomy. Statistically significant differences between normal and inflamed pulp were found in the levels of IgG (p < 0.01), IgA (p < 0.05), IgM (p < 0.01), elastase (p < 0.05), and prostaglandin E2 (p < 0.01). These findings indicate that these factors play an important role in the pathogenesis of pulpal disease, and the sampling methods used in this study are useful for examination of pulpal inflammation.

Annual review of selected dental literature: report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

The annual review of selected dental literature this year cites 384 published papers and reports. This year's review contains more editorial comment than reviews of years passed. New data on the biological responses to materials is emphasized in several sections. Observations on new compounds able to prevent plaque formation are presented. Clinically relevant advances in knowledge concerning the etching of different tooth structures are reported along with the effect of etching procedures on the dental pulp. Evaluation of periodontal diseases in all age groups is a topic. Limitations of current diagnostic techniques in periodontal disease, temporomandibular disorders, and implant therapy are included. There are new views on the use of dental amalgam. The future use of dental mercury is predicted. Interest in new ceramic systems is indicated as the demand for esthetics continues. Clinical information is emphasized over scientific information throughout this year's review.