Evaluation of Pulpal and Salivary Neuropeptides in Dental Pain (PAIN-SPCGRP)

Evaluation of Salivary and Pulpal Levels of Substance P and Calcitonin Gene-Related Peptide in Relation to Dental Pain, Pulpal Inflammation, and Psychological Status

This observational cross-sectional study is designed to evaluate pulpal and salivary levels of Substance P (SP) and Calcitonin Gene-Related Peptide (CGRP) in individuals with and without dental pain. The study aims to assess the associations between neuropeptide levels, pain severity, histopathological pulpal inflammation, and psychological status including depression, anxiety, and stress. By integrating biological and psychosocial parameters, this study seeks to contribute to a comprehensive understanding of the multifactorial nature of dental pain.

Study Overview

• Status: Completed
• Conditions: Anxiety; Pulpitis; Psychological Stress; Dental Pain; Pulpal Inflammation

Detailed Description

Dental pain is a multifactorial condition influenced by peripheral inflammatory processes, neurogenic mechanisms, and psychological factors. Neuropeptides such as Substance P (SP) and Calcitonin Gene-Related Peptide (CGRP) are known to play an important role in pain transmission and pulpal inflammatory responses. However, the invasive nature of pulpal sampling limits the routine clinical application of pulpal biomarkers, emphasizing the need to investigate non-invasive biological media such as saliva.

This observational cross-sectional study includes adult participants who require endodontic treatment and are categorized into painful and painless groups based on clinical examination and pain assessment using the Verbal Rating Scale (VRS). Pulp tissue samples are obtained during routine endodontic access procedures, and unstimulated saliva samples are collected before and after the clinical procedure. Levels of SP and CGRP in pulp and saliva samples are measured using enzyme-linked immunosorbent assay (ELISA).

Psychological status is evaluated using the Depression Anxiety Stress Scale-21 (DASS-21) to assess levels of depression, anxiety, and stress. Pulpal inflammation is evaluated through histopathological examination of pulp tissue samples using a semi-quantitative scoring system.

The primary objective of this study is to evaluate the relationship between dental pain and pulpal and salivary neuropeptide levels. Secondary objectives include assessing the associations between neuropeptides, psychological status, pain severity, and histopathological pulpal inflammation. The study is designed to provide descriptive and associative data without intervention, supporting a biopsychosocial framework for understanding dental pain and exploring the potential clinical relevance of salivary biomarkers.

• Study Type: Observational
• Enrollment (Actual): 72

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • onikişubat
    • Kahramanmaraş, onikişubat, Turkey (Türkiye), 46010
      • Kahramanmaras Sutcu Imam University, Faculty of Dentistry

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

The study population consists of adult individuals aged 18 to 65 years who present to a university dental hospital and require endodontic treatment for permanent teeth. Participants include individuals with dental pain and individuals without dental pain, classified based on clinical examination and pain assessment. All participants are systemically healthy or have ASA physical status I or II and provide written informed consent prior to participation.

Description

Inclusion Criteria:

• Adults aged 18-65 years
• ASA physical status I or II
• Presence of permanent teeth requiring endodontic treatment
• Ability to understand the study procedures and provide written informed consent
• No use of analgesic medications within 24 hours prior to clinical assessment
• No food or drink intake within 2 hours prior to saliva sampling

Exclusion Criteria:

• Periodontal disease (probing depth >4 mm or bleeding on probing >20%)
• Systemic inflammatory, autoimmune, neuropathic, or chronic pain disorders
• Acute infection, fever, or antibiotic use within the last 7 days
• Pregnancy or lactation
• Regular use of psychiatric medications (e.g., antidepressants, anxiolytics, antipsychotics, antiepileptics)
• Tobacco use or alcohol consumption within the last 24 hours
• Previous endodontic treatment or history of dental trauma in the study tooth
• Systemic diseases that may affect neuropeptide levels (e.g., diabetes mellitus, thyroid disorders, renal or hepatic disease)
• Use of medications affecting salivary flow

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
Painful Group; Participants presenting with dental pain who require endodontic treatment and report pain based on clinical examination and Verbal Rating Scale assessment.
Painless Group; Participants without dental pain who require endodontic treatment and report no pain based on clinical examination and Verbal Rating Scale assessment.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Pulpal Calcitonin Gene-Related Peptide (CGRP) Concentration	Calcitonin Gene-Related Peptide (CGRP) concentration measured in pulpal tissue samples collected during routine endodontic access. CGRP levels are quantified using enzyme-linked immunosorbent assay (ELISA) and expressed as picograms per milligram of pulp tissue (pg/mg). Higher values indicate increased neurogenic activity and pulpal stress.	Periprocedural (single assessment at the time of endodontic access)
Salivary Substance P (SP) Concentration - Baseline	Substance P (SP) concentration measured in unstimulated whole saliva samples collected before the clinical procedure. SP levels are analyzed using enzyme-linked immunosorbent assay (ELISA) and expressed as picograms per milliliter (pg/mL). Higher values indicate increased neurogenic and stress-related activity.	Baseline (prior to clinical procedure)
Salivary Substance P (SP) Concentration - Periprocedural	Substance P (SP) concentration measured in unstimulated whole saliva samples collected immediately after the clinical procedure. SP levels are analyzed using enzyme-linked immunosorbent assay (ELISA) and expressed as picograms per milliliter (pg/mL). Higher values indicate increased neurogenic and stress-related activity.	Periprocedural (immediately after the clinical procedure; single assessment)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Dental Pain Severity (Verbal Rating Scale - VRS)	Dental pain severity assessed using the Verbal Rating Scale (VRS) with the following categories: 0 = No pain; = Mild pain; = Moderate pain; = Severe pain The scale ranges from 0 to 3, with higher scores indicating greater pain severity.	Baseline (at clinical examination prior to treatment)
Psychological Status - Depression Anxiety Stress Scale-21 (DASS-21)	Psychological status assessed using the Depression Anxiety Stress Scale-21 (DASS-21), consisting of three subscales: depression, anxiety, and stress. Each subscale score ranges from 0 to 42, with higher scores indicating worse psychological status.	Baseline (at clinical examination prior to treatment)
Histopathological Pulpal Inflammation Score	Degree of pulpal inflammation assessed by histopathological examination of pulp tissue samples using a semi-quantitative scoring system: 0 = No inflammation; = Mild inflammation; = Moderate inflammation; = Severe inflammation Higher scores indicate greater inflammatory severity.	Periprocedural (after pulp tissue collection during endodontic access)
Correlation Between Neuropeptide Levels and Psychological Parameters	Correlation analysis between: Pulpal CGRP concentration (pg/mg), Salivary Substance P concentration (pg/mL), and Psychological parameters (depression, anxiety, stress scores measured by DASS-21). Associations are evaluated using appropriate statistical correlation analyses. This outcome does not represent a new biological measurement but an analytical relationship between predefined outcomes.	Baseline (single assessment during study participation)

Collaborators and Investigators

• Sponsor: Kahramanmaras Sutcu Imam University

Study record dates

Study Major Dates

• Study Start (Actual): November 1, 2024
• Primary Completion (Actual): September 1, 2025
• Study Completion (Actual): November 15, 2025

Study Registration Dates

• First Submitted: December 12, 2025
• First Submitted That Met QC Criteria: January 8, 2026
• First Posted (Actual): January 9, 2026

Study Record Updates

• Last Update Posted (Actual): January 9, 2026
• Last Update Submitted That Met QC Criteria: January 8, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Keywords: Depression; Anxiety; Substance P; Dental Pain; Psychological Stress; Calcitonin Gene-Related Peptide; Saliva Biomarkers; Pulpal Inflammation
• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Stomatognathic Diseases; Mental Disorders; Dental Pulp Diseases; Tooth Diseases; Behavioral Symptoms; Facial Pain; Pathological Conditions, Signs and Symptoms; Behavior; Signs and Symptoms; Anxiety Disorders; Depression; Pulpitis; Stress, Psychological; Toothache
• Other Study ID Numbers: HRÜ/24.15.46 (Other Identifier: Harran University Medical Ethics Committee)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: De-identified individual participant data (IPD) will not be shared due to ethical restrictions, institutional policies, and the sensitive nature of biological and psychological data collected in this study.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No