Determination of RNA/DNA Damage Associated With Oxidative Stress in Periodontitis Patients

December 1, 2025 updated by: Zehra Hasgül

Evaluation of Smoking and Oxidative Stress-Induced RNA and DNA Damage in Patients With Stage III Periodontitis

This study looked at whether a type of gum disease called Stage III periodontitis and cigarette smoking are linked to higher levels of "oxidative stress." Oxidative stress can damage DNA and RNA, which are important parts of our cells. Two markers in saliva-8-OHdG (a sign of DNA damage) and 8-OHG (a sign of RNA damage)-were measured to understand this.

Researchers included four groups of adults: smokers with periodontitis, non-smokers with periodontitis, healthy smokers, and healthy non-smokers. All participants had a dental exam, which checked things like gum inflammation, bleeding, and pocket depth. After the exam, an unstimulated saliva sample was collected from each person. The samples were tested in a laboratory using a sensitive method that measures oxidative damage.

The study found that people with periodontitis had higher levels of DNA and RNA damage in their saliva than healthy people. The highest levels were seen in smokers with periodontitis. Even healthy smokers showed higher levels of oxidative stress than healthy non-smokers. In general, worse gum disease was linked to higher levels of oxidative damage.

These results suggest that saliva tests for 8-OHdG and 8-OHG may help identify gum disease in a simple, non-invasive way. The findings also show that smoking adds to the body's oxidative stress, especially when gum disease is present. The study provides new information about how smoking and gum disease together may affect cell health.

Study Overview

Status

Completed

Conditions

Detailed Description

Periodontitis is a chronic inflammatory disease that leads to the progressive destruction of the tooth-supporting tissues. Oxidative stress plays a central role in its pathogenesis, as excessive production of reactive oxygen species (ROS) can damage cellular structures, including lipids, proteins, and nucleic acids. Among oxidative stress-related biomarkers, 8-hydroxy-2'-deoxyguanosine (8-OHdG) and 8-hydroxyguanosine (8-OHG) are widely recognized indicators of DNA and RNA damage, respectively. These biomarkers reflect the biochemical consequences of oxidative stress and are increasingly used to evaluate host responses in periodontal disease.

Cigarette smoking is one of the strongest environmental risk factors for periodontitis and is known to enhance oxidative stress through multiple mechanisms. However, the combined effect of smoking and advanced periodontitis on salivary oxidative DNA and RNA damage has not been fully clarified. Assessing both 8-OHdG and 8-OHG simultaneously may provide deeper insight into the molecular pathways linking smoking, inflammation, and periodontal tissue destruction.

This study was designed to evaluate salivary levels of oxidative nucleic acid damage in individuals with Stage III periodontitis who smoke or do not smoke, as well as in periodontally healthy controls. The study also aimed to investigate the relationship between these biomarkers and clinical periodontal measurements. By examining DNA and RNA oxidation together, the study sought to provide a multidimensional understanding of the host oxidative response in periodontitis.

All participants underwent full-mouth periodontal examination performed by a calibrated clinician. Unstimulated saliva samples were collected under standardized morning conditions, processed by centrifugation to remove cellular debris, and stored at -80°C until biochemical analysis. Levels of 8-OHdG and 8-OHG were quantified using a high-sensitivity ELISA method capable of detecting multiple oxidized guanine derivatives.

Biochemical findings demonstrated that oxidative DNA and RNA damage levels were higher in individuals with periodontitis compared to healthy controls, with smokers exhibiting the highest levels overall. Oxidative biomarker levels showed positive correlations with key periodontal parameters, including probing depth, clinical attachment loss, plaque accumulation, gingival inflammation, and bleeding on probing. These results suggest that the inflammatory burden of periodontitis amplifies oxidative stress at the nucleic acid level and that smoking contributes an additional biological load.

In addition to biochemical assessment, buccal mucosa samples were evaluated cytologically using hematoxylin and eosin staining. All specimens showed adequate cellularity, and no significant differences in epithelial dysplasia were observed across study groups. This may be related to the predominance of superficial epithelial cells in the collected samples.

Overall, this study provides an integrated biochemical and cytomorphological assessment of oxidative stress in periodontitis. The findings support the potential use of salivary 8-OHdG and 8-OHG as non-invasive biomarkers for disease monitoring and contribute novel evidence regarding the interaction between smoking, oxidative stress, and periodontal inflammation.

Study Type

Observational

Enrollment (Actual)

88

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Turkey (Türkiye)
    • Yenimahalle
      • Ankara, Yenimahalle, Turkey (Türkiye), 06560
        • Ankara University Faculty of Dentistry, Department of Periodontology

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

The study population consisted of systemically healthy adults aged 18-65 years, including individuals with Stage III periodontitis and periodontally healthy controls. Participants were categorized into four groups based on periodontal status and smoking habits: smokers and non-smokers with Stage III periodontitis, and smokers and non-smokers who were periodontally healthy.

Description

Inclusion Criteria:

  • Individuals aged 18 years or older
  • Having at least 16 permanent teeth, excluding third molars
  • Not using orthodontic appliances
  • Not pregnant or breastfeeding
  • Systemically healthy individuals with no systemic diseases that could affect periodontal status
  • No use of anti-inflammatory or antimicrobial medications within the last 6 months
  • No periodontal treatment within the last 12 months

Exclusion Criteria:

  • Pregnant or breastfeeding individuals.
  • Use of anti-inflammatory or antimicrobial drugs in the past 6 months.
  • Use of antioxidant supplements in the past 3 months.
  • Periodontal treatment within the past 12 months.
  • Diagnosis of psychiatric disorders.
  • Any oral infection.
  • Fewer than 16 permanent teeth (excluding third molars).
  • Alcohol dependence.
  • Active infectious diseases (Acute hepatitis, AIDS, tuberculosis), malignancy, or any systemic condition that may affect periodontal tissues.
  • Current use of medications known to affect periodontal tissues (phenytoin, cyclosporine A, calcium channel blockers).

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Periodontitis Smoker
Participants diagnosed with Stage III periodontitis who are current cigarette smokers. No intervention was applied; biological samples (unstimulated saliva) were collected for biomarker analysis.
Periodontitis Non-Smoker
Participants diagnosed with Stage III periodontitis who do not smoke. No intervention was applied; unstimulated saliva samples were collected for laboratory analysis.
Healthy Smoker
Periodontally healthy individuals who are current smokers. No treatment or intervention was performed; only saliva samples and periodontal measurements were obtained.
Healthy Non-Smoker
Periodontally healthy non-smokers. No intervention was provided; participants underwent periodontal evaluation and saliva sample collection.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Salivary oxidative DNA and RNA damage (8-OHdG and 8-OHG levels)
Time Frame: Baseline (periodontal examination visit and saliva collection visit, before any periodontal treatment)
Concentrations of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and 8-hydroxyguanosine (8-OHG) measured in unstimulated whole saliva using a high-sensitivity competitive ELISA kit. Saliva samples are collected at a separate baseline visit within the study period, after full-mouth periodontal examination and before any periodontal therapy. Biomarker levels (ng/mL) were compared across the four study groups and analyzed in relation to clinical periodontal parameters. Higher values indicate greater oxidative nucleic acid damage.
Baseline (periodontal examination visit and saliva collection visit, before any periodontal treatment)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Zehra Hasgül

Investigators

  • Principal Investigator: Sivge Kurgan, Ankara University, Faculty of Dentistry, Department of Periodontology

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

May 5, 2025

Primary Completion (Actual)

August 4, 2025

Study Completion (Actual)

August 15, 2025

Study Registration Dates

First Submitted

December 1, 2025

First Submitted That Met QC Criteria

December 1, 2025

First Posted (Actual)

December 12, 2025

Study Record Updates

Last Update Posted (Actual)

December 12, 2025

Last Update Submitted That Met QC Criteria

December 1, 2025

Last Verified

December 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • ZH-2025-OxidativeStress

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Individual participant data will not be shared due to patient privacy concerns, data protection regulations, and the terms of the local ethics committee approval

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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