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.

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.

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

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.

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.