Comparative study of substance P and neurokinin A in gingival crevicular fluid of healthy and painful carious permanent teeth

Gingival Crevicular Fluid Levels of Neurokinin A and Substance P in Patients with Symptomatic Irreversible Pulpitis: A Systematic Review and Meta-Analysis

Aims and Objectives

The levels of neuropeptides neurokinin A (NKA) and substance P (SP) in the gingival crevicular fluid of patients with symptomatic irreversible pulpitis (SIP) were evaluated using a comprehensive review and meta-analysis.

Materials and Methods

The data bases of Pubmed, Scopus, EBSCOhost, Science Direct, Proquest and Cochrane library databases were thoroughly searched. The quality of the study was evaluated using the Joanna Briggs Criteria. Twenty four studies were listed following a thorough search of full texts, abstracts, and removal of duplicates. Only two of these papers were eligible for inclusion in the meta-analysis. Since the results obtained were in mean and standard deviation, the levels of neuropeptides in the test and control groups were examined using the meta-analysis.

Results

When compared with healthy teeth, NKA was not significantly elevated in GCF of individuals with SIP (P = 0.06; odd ratio = 1.34 [-0.05 to 2.74] at 95% confidence interval [CI]). Additionally, there was no evidence of an association between SP and SIP (P = 0.08; odds ratio = 0.84 [-0.10 to 1.77] at 95% CI).

Conclusion

This systematic research demonstrated that in individuals with SIP, NKA, and SP are not substantially linked. However, the lack of study in this area makes it evident that additional research is needed, particularly in relation to pulpal disorders and NKA.

A Mini Review: The Potential Biomarkers for Non-invasive Diagnosis of Pulpal Inflammation

For assessing the adequacy of vital pulp therapy for an inflamed pulp, the use of non-invasive diagnostic tools is necessary to avoid further damage to the teeth. Detection of biomarkers that are indicative of the inflammatory status in pulp can be a promising tool for this purpose. These biomarkers need to be reliably correlated with pulpal inflammation and to be easily detected without pulp exposure. This mini-review article aims to review biomarkers that are present in gingival crevicular fluid (GCF) in inflamed pulp conditions. Several studies have reported the availability of various biomarkers including cytokines, proteases, elastase, neuropeptides, and growth factors. Non-invasive pulpal diagnostic methods will be useful as well to determine reversibility, irreversibility, or necrosis of inflamed pulp. These types of molecular diagnoses via analyzing the proteome have revolutionized the medical field, and are one of the most promising empirical methodologies that a clinician can utilize for the proactive identification of pulpal disease.

Enhanced Neurokinin-1 Receptor Expression Is Associated with Human Dental Pulp Inflammation and Pain Severity

Substance P (SP) is a peptide involved in many biological processes, including nociception and inflammation. SP has a high affinity for its receptor neurokinin-1 (NK-1R). SP/NK-1R complex plays a major role in the interactions going on during the onset of dental pain and inflammation. Objective. To identify the expression of NK-1R in healthy and inflamed human dental pulp, as well as to identify any association with severity of dental pain. Methods. This case-control study included ten irreversibly inflamed samples of dental pulp, which were extirpated from patients presenting with chief complaint of dental pain due to caries. Ten healthy pulps, extirpated from those teeth which were indicated for extraction due to orthodontic reasons, were used as the control group. Visual analog scale (VAS) and modified McGill Pain Questionnaire were used to assess the characteristic and severity of pain. Immunohistochemical study was performed using monoclonal antibodies against NK-1R. Results. The results showed that the NK-1R was expressed intensely in patients with higher pain score. The mean pain score in cases was 7.0 ± 2.0. The healthy dental pulps had negative or mild NK-1R staining of +1 intensity. The NK-1R score in cases was 2.4 ± 0.516 and 0.2 ± 0.4216 in controls. There was significant difference in NK-1R score between both groups (p value <0.05). There was a strong positive correlation between the pain score and NK-1R expression score. As the pain increased, the NK-1R expression score was also increased (0.95^∗∗, p value 0.000). Conclusions. NK-1R is overexpressed in inflamed dental pulp. SP/NK-1R modulation may provide a novel approach for the treatment of pulpal inflammation and pain.

Comparison of Neurokinin A, Substance P, Interleukin 8, and Matrix Metalloproteinase-8 Changes in Pulp tissue and Gingival Crevicular Fluid Samples of Healthy and Symptomatic Irreversible Pulpitis Teeth

INTRODUTION

The aim of this study was to compare levels of neurokinin A (NKA), substance P (SP), interleukin (IL)-8, and matrix metalloproteinase-8 (MMP-8) in pulp tissue and gingival crevicular fluid (GCF) samples of healthy and symptomatic irreversible pulpitis teeth.

METHODS

Forty patients diagnosed with healthy and symptomatic irreversible pulpitis teeth were included in this study. NKA, SP, IL-8, and MMP-8 levels were measured using the enzyme-linked immunosorbent assay test after pulp and GCF samples were obtained from healthy (n = 20) and symptomatic irreversible pulpitis teeth (n = 20). GCF sampling of 40 teeth was repeated 1 week later. Routine root canal treatment procedures of the teeth were performed, and the treatment process was completed. As a control group, GCF samples were taken from the contralateral teeth in both groups. Statistical analysis was performed using dependent and independent t tests, analysis of variance, Kruskal-Wallis, Mann-Whitney U tests, and Pearson correlation analysis.

RESULTS

Comparing the groups, all mediator levels were significantly higher in the pulp samples in the pulpitis group compared with the healthy group (NKA: P < .001, SP: P = .005, IL-8: P < .001, and MMP-8: P < .001). Likewise, in the pulpitis group, all mediator levels were significantly higher in the first GCF samples compared with the healthy group (NKA: P = .01, SP: P < .001, IL-8: P = .001, and MMP-8: P < .001).

CONCLUSIONS

It was observed that NKA, SP, IL-8, and MMP-8 increased significantly in pulp tissue and GCF specimens of symptomatic irreversible pulpitis teeth compared with pulp tissue and GCF specimens of healthy teeth. Second, it was determined that NKA, SP, IL-8, and MMP-8 levels decreased significantly in GCF samples in teeth diagnosed with symptomatic irreversible pulpitis 1 week after the removal of inflamed pulp. Finally, SP, IL-8, and MMP-8 levels were found to be higher in pulp tissue samples of the patients with symptomatic irreversible pulpitis with higher pain scores than those with low pain scores.

Comparison of the Level of Substance P and Neurokinin A in Gingival Crevicular Fluid of Sound and Symptomatic Carious Primary Teeth by ELISA

OBJECTIVES

Pulpal inflammation is often associated with odontogenic pain. Dental pulp is abundantly innervated with sensory fibers encompassing neuropeptides. Neurokinin A (NKA) and substance P (SP) are important neuropeptides in the dental pulp that can cause neurogenic inflammation. Since no previous study has assessed dental pulp neuropeptides in children, this study aimed to compare the level of NKA and SP in gingival crevicular fluid (GCF) of sound and symptomatic carious primary teeth.

MATERIALS AND METHODS

Samples of GCF were obtained of 20 sound and 20 painful carious primary teeth. Enzyme-linked immunosorbent assay (ELISA) was used to quantify neuropeptides in GCF. Data were analyzed using paired t-test, ANOVA, Kolmogorov-Smirnov test and correlation coefficient test.

RESULTS

A significant difference was noted in the level of NKA in GCF of painful and sound teeth (2.23 pg/ml in painful, and 1.84 pg/ml in sound teeth, P<0.05). The difference between the two groups regarding SP was not significant (2.23 pg/ml in painful, and 2.02 pg/ml in sound teeth, P>0.05).

CONCLUSIONS

The results showed that the level of NKA and SP was higher in GCF of painful teeth compared to that of sound teeth. This difference was statistically significant with regard to NKA. Thus, these neuropeptides can serve as indicators for pathological activities in teeth with symptomatic irreversible pulpitis.