Characterization of Pulp Inflammation: an Observational Study Using Biological Samples Collected During Routine Dental Care (INFLAPULP)

Background: Vital pulp therapy (VPT) is a cornerstone of minimally invasive dentistry and aims to preserve pulp vitality whenever clinically feasible. Teeth with vital pulp show better long-term survival than endodontically treated teeth. However, the success of VPT procedures-such as indirect or direct pulp capping, partial pulpotomy, and full pulpotomy-critically depends on an accurate assessment of the extent and severity of pulpal inflammation. Current diagnostic classifications are mainly based on patient-reported symptoms and sensibility tests, which do not reliably reflect the underlying inflammatory status of the pulp tissue. This diagnostic uncertainty contributes to inappropriate treatment selection, early therapeutic failures, and wide variability in clinical practice.

Rationale: Pulpal inflammation is a dynamic and spatially heterogeneous biological process that progresses from localized to diffuse tissue involvement. Clinical studies have demonstrated discrepancies between clinical diagnosis and the actual histological and molecular status of the pulp. A new diagnostic classification (Endolight) has been proposed to better guide VPT indications by distinguishing different stages of pulpal inflammation, but it has not yet been validated against in situ biological analyses of human pulp tissue. Moreover, the identification of molecular and protein biomarkers associated with inflammatory severity could support the development of more accurate diagnostic and prognostic tools for endodontic decision-making.

Objectives: The primary objective of this study is to characterize the immune and inflammatory response of human dental pulp at the tissue, transcriptomic, and proteomic levels using biological samples obtained during routine dental care. Secondary objectives are to assess the concordance between clinical diagnostic categories-particularly those of the Endolight classification-and pulpal inflammatory profiles, and to explore associations between inflammatory profiles and patient-related or tooth-related factors.

Methods: This is a prospective, monocentric observational study conducted at the Department of Dental Medicine of Pitié-Salpêtrière Hospital. Pulp tissue samples and whole pulp-containing teeth are collected as operative waste during routine endodontic treatments or tooth extractions. Samples are pseudonymized and processed according to the planned analyses. Transcriptomic profiling is performed using RNA sequencing, with validation by RT-qPCR, in situ hybridization and RNAscope. Protein expression and activity are assessed using proteomic approaches, ELISA assays, and immunohistochemical or immunofluorescence analyses. Clinical, demographic, and dental data are collected from medical records using a secured electronic case report form.

Outcomes: Primary outcomes include the identification and characterization of inflammatory gene and protein expression profiles in human dental pulp. Secondary outcomes include the concordance between clinical diagnoses and biological inflammatory profiles, as well as the identification of molecular biomarkers potentially relevant for guiding VPT indications.

Expected impact: By improving the biological characterization of pulpal inflammation and its relationship with clinical diagnosis, this study aims to support more precise, biology-driven decision-making in vital pulp therapy and the management of endodontic emergencies.

Study Overview

• Status: Not yet recruiting
• Conditions: Pulpal Inflammation

Detailed Description

Vital pulp therapy (VPT) is a key component of minimally invasive dentistry and aims to preserve pulp vitality whenever clinically feasible. Teeth with vital pulp have been shown to exhibit better long-term survival than endodontically treated teeth. Consequently, VPT procedures-including indirect pulp capping, direct pulp capping, partial pulpotomy, and full pulpotomy-should be preferred over root canal treatment when the biological status of the pulp allows it.

The success of VPT relies on two essential factors: the use of bioactive materials capable of promoting pulpal healing, and an accurate assessment of the severity and extent of pulpal inflammation. However, complications related to inappropriate case selection remain frequent and often occur within the first year following treatment. These failures are largely attributed to the difficulty of precisely evaluating the inflammatory status of the pulp, highlighting a major unmet need in endodontic diagnosis, particularly in the context of emergency care.

Pulpal inflammation is a defense response of the dental pulp to external aggression such as carious lesions, fractures, periodontal disease, or restorative procedures. This biological process is dynamic, progressive, and spatially heterogeneous. Inflammation initially develops locally in the pulp tissue adjacent to the injury and may subsequently extend to involve the entire coronal pulp and, in more advanced stages, the radicular pulp. When inflammation remains confined to the coronal pulp, removal of the inflamed tissue through partial or total pulpotomy followed by the application of a bioactive material may be sufficient to achieve healing and long-term success.

At the clinical level, however, the assessment of pulpal inflammation remains challenging. The most widely used diagnostic classification of pulpal diseases is mainly based on patient-reported pain characteristics and responses to thermal sensibility tests. This classification distinguishes healthy pulp, reversible pulpitis, irreversible pulpitis (acute or chronic), and pulp necrosis. Intraoperative criteria, such as the evaluation of bleeding and hemostasis, are sometimes used to estimate pulpal status, but these criteria remain subjective and poorly standardized.

Several studies have demonstrated discrepancies between clinical diagnosis and the actual histological condition of the pulp tissue. Moreover, the current diagnostic framework does not allow a clear correspondence between clinical diagnosis and the indication for specific VPT procedures. While four VPT techniques are available, only three inflammatory diagnostic categories are recognized, which contributes to uncertainty in therapeutic decision-making and significant variability in clinical practice.

In 2017, a new diagnostic classification known as the Endolight classification was proposed. Based on histological observations of inflamed pulp tissue and prognostic data from VPT outcomes, this classification distinguishes between initial, mild, moderate, and severe pulpitis. It aims to better guide treatment selection and reduce variability in clinical practice. However, this classification has not yet been validated through studies directly comparing clinical diagnosis with in situ biological analyses of human pulp tissue.

At the tissue and molecular levels, several studies have explored the mechanisms underlying pulpal inflammation. Histologically, reversible forms of pulpitis are characterized by preserved odontoblastic layer continuity and absence of necrotic tissue, whereas irreversible forms are associated with disruption of the odontoblastic layer, inflammatory infiltrates, necrosis, or abscess formation. Molecular studies have identified several inflammatory mediators whose expression increases with the severity of pulpal inflammation, including interleukin-8 (IL-8), matrix metalloproteinase-9 (MMP-9), and tumor necrosis factor alpha (TNF-α). The identification of reliable molecular and cellular biomarkers remains a major challenge but represents a critical step toward the development of more accurate diagnostic and prognostic tools.

The present study is designed to characterize the immuno-inflammatory profiles of human dental pulp across different clinical forms of pulpal inflammation by integrating clinical, transcriptomic, and proteomic data. This is a prospective, monocentric observational study conducted at the Department of Dental Medicine of Pitié-Salpêtrière Hospital. Patients are recruited during routine dental care, and pulp tissue samples or whole pulp-containing teeth are collected as operative waste during endodontic treatment or tooth extraction. No additional procedures are performed, and patient care is not modified by participation in the study.

Adult patients (≥18 years) whose pulp tissue is removed as part of standard care and who do not express opposition to participation are eligible for inclusion. Patients who have taken anti-inflammatory medication within 12 hours prior to the procedure or who are under legal protection are not included. Each participant is included for a single visit corresponding to the dental procedure during which the sample is collected, with no subsequent clinical follow-up.

Clinical and demographic data are extracted from medical records and include patient-related variables (age, sex, medical history, medication, pain intensity assessed using a visual analog scale) and tooth-related variables (clinical pulpal diagnosis according to both the current classification and the Endolight classification, tooth type and number, oral pathology affecting the tooth and its severity, restorative status and quality, and radiographic parameters).

Biological samples are pseudonymized at the time of collection and processed according to the planned analyses. Transcriptomic profiling is performed using RNA sequencing, with validation by real-time quantitative PCR and in situ hybridization. Proteomic analyses, including degradomic approaches, are performed using mass spectrometry; this component of the study is conducted within a specific project funded by the French National Research Agency (ANR), whose objectives are fully integrated and compatible with the present protocol. Protein expression is further assessed using ELISA assays and immunohistochemical or immunofluorescence analyses.

The primary outcome of the study is the identification and characterization of immuno-inflammatory gene and protein expression profiles in human dental pulp tissue according to the clinical diagnosis of pulpal inflammation. Secondary outcomes include the assessment of concordance between clinical diagnostic categories-particularly those of the Endolight classification-and biological inflammatory profiles, as well as the analysis of associations between inflammatory profiles and patient-related or tooth-related factors.

Biological samples are stored only for the duration of the research and are used exclusively for the analyses described in this protocol. All samples are destroyed at the end of the study, and no long-term biological collection is constituted.

By providing an integrated clinical and biological characterization of pulpal inflammation, this study aims to support more precise, biology-driven diagnostic and therapeutic decision-making, improve the indication of vital pulp therapies, and ultimately optimize the management of endodontic emergencies.

• Study Type: Observational
• Enrollment (Estimated): 1200

Contacts and Locations

• Study Contact: Name: Marjolaine GOSSET, Dental surgeon, Professor; Phone Number: 33682776276; Email: marjolaine.gosseti@aphp.fr

Participation Criteria

Eligibility Criteria

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

• Sampling Method: Non-Probability Sample

Study Population

Adult patients (≥18 years old) whose pulp tissue must be removed during routine dental care, either through endodontic treatment or tooth extraction for orthodontic, surgical, prosthetic, or periodontal reasons.

- Patients who have been informed about the study and have not expressed opposition to participation

Description

Inclusion Criteria:

• - Adult patients (≥18 years old) whose pulp tissue must be removed during routine dental care, either through endodontic treatment or tooth extraction for orthodontic, surgical, prosthetic, or periodontal reasons.
• Patients who have been informed about the study and have not expressed opposition to participation

Exclusion Criteria:

• - Patients who have taken anti-inflammatory medication within 12 hours prior to the dental procedure.
• Patients under legal protection measures (e.g., guardianship or curatorship).

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Gene expression levels in inflamed dental pulp tissues	Quantitative assessment of gene expression levels using RNA sequencing (normalized expression counts), comparing different clinical diagnosis of pulpitis (according to Endolight classification).	At the time of pulp tissue collection (baseline)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Relative gene expression validation by RT-qPCR profile	Measurement of relative gene expression using RT-qPCR (ΔCt or fold change values) to validate RNA-seq results.	At the time of pulp tissue collection (baseline)
Protein concentration levels in inflamed dental pulp tissues	Quantification of inflammatory protein levels using ELISA assays (pg/mL), according to clinical forms of pulpitis.	At the time of pulp tissue collection (baseline)
Protein abundance profiles by mass spectrometry	At the time of pulp tissue collection (baseline)	Assessment of protein abundance and degradation patterns using mass spectrometry-based proteomics (relative intensity or spectral counts).
Cytokines expression in pulp tissues	immunofluorescence evaluation of protein expression in pulp tissues (confocal microscopy analysis)	At the time of pulp tissue collection (baseline)
Association between molecular markers and clinical parameters	Statistical correlation between molecular measurements (gene and protein expression levels) and clinical variables (pulpitis diagnosis, pain score, and tooth characteristics).	At the time of pulp tissue collection (baseline)
Spatial gene expression by RNAscope in inflamed pulp tissues	Semi-quantitative assessment of gene expression at the cellular level using RNAscope in situ hybridization, based on signal quantification (number of RNA puncta per cell or scoring system), according to clinical forms of pulpitis.	At the time of pulp tissue collection (baseline)

Collaborators and Investigators

• Sponsor: Assistance Publique - Hôpitaux de Paris
• Investigators: Principal Investigator: Marjorie ZANINI, Dental surgeon, Associate Prof, Assistance Publique - Hôpitaux de Paris

Study record dates

Study Major Dates

• Study Start (Estimated): September 1, 2026
• Primary Completion (Estimated): September 1, 2031
• Study Completion (Estimated): September 1, 2031

Study Registration Dates

• First Submitted: February 4, 2026
• First Submitted That Met QC Criteria: April 9, 2026
• First Posted (Actual): April 16, 2026

Study Record Updates

• Last Update Posted (Actual): April 16, 2026
• Last Update Submitted That Met QC Criteria: April 9, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: diagnosis; Pulpitis; vital pulp therapy; human pulp
• Additional Relevant MeSH Terms: Stomatognathic Diseases; Pathologic Processes; Dental Pulp Diseases; Tooth Diseases; Pathological Conditions, Signs and Symptoms; Disease; Pulpitis
• Other Study ID Numbers: APHP250930

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES

IPD Plan Description

The procedures carried out with the French data privacy authority (CNIL, Commission nationale de l'informatique et des libertés) do not provide for the transmission of the database, nor do the information and consent documents signed by the patients.

Consultation by the editorial board or interested researchers of individual participant data that underlie the results reported in the article after deidentification may nevertheless be considered, subject to prior determination of the terms and conditions of such consultation and in respect for compliance with the applicable regulations.

• IPD Sharing Time Frame: Beginning 3 months and ending 3 years following article publication. Requests out of these time frame can also be submitted to the sponsor
• IPD Sharing Access Criteria: Researchers who provide a methodologically sound proposal.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; ICF

Drug and device information, study documents

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