Extended Abstract

Introduction
Rheumatoid arthritis (RA) is an autoimmune inflammatory disease that affects joint tissues, including synovial fluid, joint cartilage, and bone. This condition affects 0.5-1% of the global population, occurring three times more frequently in women than in men. RA and periodontitis are multifactorial diseases characterized by periods of remission and progression. The prevalence and severity of periodontal disease and tooth loss are higher in patients with RA compared to healthy individuals, and conversely, the prevalence of RA is higher in patients with periodontitis than those without periodontal disease. Impaired hand function in RA patients negatively affects their oral hygiene, leading to increased plaque accumulation and the development of periodontitis. Periodontitis may act as a risk factor for the initiation and progression of RA. Given the role of the immune system and inflammatory responses in both RA and periodontitis, various anti-inflammatory and immunosuppressive drugs can impact both diseases. Different drug regimens for RA affect clinical conditions and subgingival microbial flora in periodontal patients. This study aimed to assess periodontal indices including Plaque Index (PI), Clinical Attachment Loss (CAL), Gingival Index (GI), and Bleeding on Probing (BOP) in RA patients treated with immunosuppressive drugs.
Methods
This comparative cross-sectional study was conducted on 68 RA patients (54 women and 14 men) divided into three groups based on their medication regimens: monotherapy (20 patients), dual therapy (24 patients), and triple therapy (24 patients), along with a control group of 20 healthy individuals (15 women and 5 men).
Inclusion criteria for the medication group included RA patients taking immunosuppressive drugs for 4 to 6 months with a PI below 35% (according to the O’Leary index). The control group included healthy individuals with no systemic diseases and a PI below 35%. RA patients were divided into three groups based on the number of immunosuppressive drugs (DMARDs) they were taking: monotherapy, dual therapy, and triple therapy.
Periodontal indices were measured and recorded by the researcher once for the existing teeth. Patient information such as age, gender, education level, urban or rural living, treatment duration, medications, and dosages were recorded in a checklist. Periodontal indices including Clinical Attachment Loss (CAL), Gingival Index (GI), Bleeding on Probing (BOP), and Plaque Index (PI) were evaluated. PI was calculated using a disclosing tablet (O’Leary index). Each patient was given a disclosing tablet to chew thoroughly. The color change on the teeth from the tablet was recorded on four surfaces (mesial, distal, buccal, and lingual) for each tooth, and dental plaque levels were calculated according to the O’Leary index.
Results
Among the drug-using group, 86.8% had an education level of high school diploma or lower, compared to 25% in the control group. The median PI in the control group was 29.6%, and in the dual therapy group, it was 42.3% (P<0.002). The median BOP in the control group was significantly higher than in the three medication groups (P<0.005). There was no statistically significant difference in the mean CAL and GI between the control group and the medication groups. No significant statistical differences were observed in the four periodontal indices (CAL, GI, PI, and BOP) among RA patients in the monotherapy, dual therapy, and triple therapy groups. The periodontal indices (CAL, GI, PI, and BOP) in RA patients aged ≤40 years showed no significant statistical differences between the drug-using and control groups, but BOP and GI indices were statistically significant in individuals aged ≥41 years (P<0.05).
Conclusion
According to the results of this study, no significant statistical differences were observed in the periodontal indices among RA patients treated with immunosuppressive drugs. Increasing the number of drugs only affected the BOP index, with no impact on other periodontal indices. Scientifically, this result suggests that RA patients using anti-inflammatory and anti-rheumatic drugs had a lower GI index, indicating less gingival inflammation. Additionally, since patients with a PI below 35% were included in the study, good oral hygiene likely influenced the low average GI in both the control and patient groups. In this study, 46% of RA patients in the dual and triple therapy groups used anti-TNF-α drugs such as adalimumab, infliximab, and etanercept. Additionally, the number of individuals and treatment duration were greater in the dual and triple therapy groups than in the monotherapy group. Therefore, the use of anti-rheumatic drugs, particularly biological drugs, likely reduced BOP in these patients.
In this study, periodontal indices in individuals aged ≤40 years showed no significant statistical differences between the drug-using and control groups, but BOP and GI indices were statistically significant in individuals aged ≥41 years. As age increases, treatment with immunosuppressive drugs causes changes in some periodontitis indices. The plaque index results showed a significant difference between the two groups. This finding might be due to RA patients' difficulty in effectively brushing and removing plaque due to hand joint pain, motor impairment, depression, and lack of motivation.
Limitations of this study include not evaluating the number of lost teeth and tooth mobility and not assessing the impact of non-steroidal anti-inflammatory drugs alongside DMARDs. The study was conducted during the COVID-19 pandemic, which made oral examinations challenging. Changes in RA patients' drug regimens are common, complicating drug evaluation. To achieve better results regarding the drug effect on the periodontal status of RA patients, a longitudinal study with larger sample size, including factors like smoking, diet, and stress, is recommended. It is also suggested to separately examine synthetic and biological DMARD groups and their individual effects on periodontal status, as each drug can have different impacts.
Ethical Statement
The present study was approved by the Research Ethics Committees of Ardabil University of Medical Sciences (IR.ARUMS.REC.1399.297).
Funding
This article is based on Zakiyeh Movahedzadeh's thesis for obtaining a professional doctorate in general medicine from the Faculty of Medicine, Ardabil University of Medical Sciences, Ardabil, Iran.
Conflicts of Interest
The authors have no conflicts of interest.
Acknowledgement
We thank the Research and Technology Vice-Chancellor of Ardabil University of Medical Sciences and the Faculty of Dentistry for their cooperation in conducting this study.

Key Message
Immunosuppressive drugs do not significantly affect the periodontal indices in patients with rheumatoid arthritis.