Maintenance visit regularity has a different impact on periodontitis-related tooth loss depending on patient staging and grading

Combined Effect of Abutment Height and Restoration Emergence Angle on Peri-Implant Bone Loss Progression: A Retrospective Analysis

INTRODUCTION

This study aimed to investigate the combined effect of trans-mucosal abutment height (TmAH) and restorative emergence angle (REA) on marginal bone loss (MBL) around bone-level implants.

METHODS

Implant radiographs 12-18 months after crown placement (T0) and at least one year later (T1) were retrospectively analyzed. Sites were separated into four groups: Long/Narrow-Angle (LN) with TmAH > 2 mm and REA < 30°, Long/Wide-Angle (LW) with TmAH > 2 mm and REA ≥ 30°, Short/Narrow-Angle (SN) with TmAH < 2 mm and REA < 30°, and Short/Wide-Angle (SW) with TmAH < 2 mm and REA ≥ 30°. MBL was calculated, and multiple linear regression analysis was performed to control for patient-level and implant/prosthesis-level factors.

RESULTS

192 implants pertaining to 119 patients were included. Group significantly influenced MBL experience (p < 0.001). Group SW experienced on average 0.48 mm (95% CI: 0.25-0.71, p < 0.001), 0.43 mm (95% CI: 0.18-0.68, p = 0.001), and 0.25 mm (95% CI: 0.00-0.45, p = 0.013) greater MBL compared to Groups LN, LW, and SN, respectively. Group was also a significant factor impacting the development of peri-implantitis (p = 0.041), with Group SW displaying a roughly 4× greater likelihood of having peri-implantitis (PI) diagnosed compared to Groups LN (OR: 4.04; p = 0.091) and LW (OR: 4.19; p = 0.013). Every 1 mm increase in TmAH significantly decreased the likelihood of MBL > 0 mm (OR = 0.63; p = 0.003).

CONCLUSIONS

Abutment height > 2 mm may play a role in reducing PI and MBL related to ≥ 30° REA around bone-level implants. REA was found to only be a significant factor when TmAH is less than 2 mm.

Prevalence of Periodontitis in a 70-Year-Old Population in Western Norway According to the ACES 2018 Classification Framework: A Cross-Sectional Study

AIM

To assess the prevalence and severity of periodontitis in an older adult population in Western Norway using the periodontitis definition by the recently published ACES 2018 Classification Framework.

MATERIALS AND METHODS

In the present study, 1298 70-year-old subjects answered a questionnaire and underwent a full-mouth periodontal examination. The prevalence of periodontitis, stages, extents and grades was presented according to the Framework applying the 2018 periodontal classification scheme in epidemiological survey (ACES). Descriptive analyses were used, and results were expressed as percentages of the total number of observations.

RESULTS

According to ACES, periodontitis was detected in 100% of the study population, and Stage II, Stage III and Stage IV were present in 21%, 75% and 4% of the individuals, respectively. The majority of periodontitis cases demonstrated generalised periodontitis and Grade B was the predominant grade in the periodontitis cases. The mean number of teeth in the study population was 25.3.

CONCLUSION

There is a high burden of periodontitis in the present population of old individuals, and the majority of participants were classified as Stage III periodontitis. The cut-offs for interdental clinical attachment loss in the definition of periodontitis affect the estimate of cases, stages and extent of periodontitis in older age groups.

Clinical Performance of the Bioperio® Protocol to Manage Periodontitis

Objectives: The aim of this study was to describe the structure and assess the efficacy of a patient-centered framework for managing periodontitis, utilizing the Bioperio® protocol, a standardized treatment approach incorporating both clinical and extra-clinical phases. Methods: Patients diagnosed with periodontitis were included in this multicenter, single-arm, clinical observational study with a 3-month follow-up. All patients were treated following the Bioperio® protocol, involving professional supra-gingival scaling, oral hygiene instructions, and scaling and root planing following a full-mouth approach. In Stage III/IV periodontitis cases, enamel matrix derivatives (EMD) were applied in periodontal pockets > 5 mm. Monthly recalls were performed until the 3-month follow-up. Results: In total, 663 patients were enrolled, with 76.4% being diagnosed with Stage II/III periodontitis. At 3 months, all clinical periodontal parameters improved regardless of the initial stage of periodontitis, achieving pocket closure in 75.4% of cases and patient resolution in 91.3% of the sample. Stages I/II showed significantly improved outcomes compared to Stage IV. The adjunct of EMDproved beneficial, especially in stage III patients, increasing pocket closure by 15% and doubling the odds of patient resolution. No adverse effects of the treatment protocol were observed throughout the study. Conclusions: The Bioperio® protocol appears to be a safe and effective therapeutic approach for the management of patients affected by periodontitis. Combining a stepwise approach for clinical phases with tailored oral hygiene instructions and motivational sessions offers a comprehensive strategy that may enhance outcomes for patients with periodontitis.

Factors associated with tooth loss in patients with stages 3 and 4 periodontitis: a short-term retrospective evaluation of patients

This retrospective study analyzed factors associated with tooth loss in patients with stages 3 and 4 periodontitis undergoing non-surgical periodontal therapy. Data from 84 patients treated at Griffith University Periodontal Clinic (2019-2022) were examined, focusing on patient factors such as smoking status, osteoporosis, and age, alongside tooth loss variables. The logistic regression analysis revealed that patients with stage 4 periodontitis had a significantly higher likelihood of tooth loss compared to those with stage 3 (odds ratio [OR] 2.12; 95% confidence interval [CI] 1.13-4.84). Smoking was also identified as a significant risk factor, with smokers showing an OR of 1.69 (95% CI 1.4-3.9) for tooth loss. While no statistically significant relationships were observed for other variables (p > 0.05), patients under 40 years and over 71 years with stage 4 periodontitis exhibited notable tooth loss outcomes (p = 0.003 and p = 0.034, respectively). These findings emphasize the importance of integrating smoking cessation programs into periodontal care and tailoring treatment strategies for high-risk groups. Further longitudinal studies with comprehensive data collection are recommended to enhance the understanding of tooth loss predictors in advanced periodontitis.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-025-04217-5.

Effect of Discontinuation of Supportive Periodontal Therapy on Periodontal Status-A Retrospective Study

AIM

To assess the impact of active (APT) and supportive periodontal therapy (SPT) on the change in probing depth (PD) and annual tooth loss in partially and fully compliant and drop-out patients.

MATERIAL AND METHODS

Data of 280 periodontally treated partially and fully compliant (regular supportive visits, SPT duration 5.5 ± 4.5 years) and 55 drop-out patients (SPT and drop-out duration 8.3 ± 3.8 years, only drop-out duration 5.3 ± 3.7 years) were recorded. PD data and the number of teeth present at the start of APT (T1) and at the start of SPT (T2) were taken from the patient files and evaluated at the time of the final examination (T3).

RESULTS

Annual tooth loss during SPT was significantly higher (p < 0.001) in drop-out patients than in partially and fully compliant patients (0.31 ± 0.50 vs. 0.19 ± 0.55, respectively). In partially and fully compliant and drop-out patients, the mean PD (all available site data) decreased significantly between T1 (3.61 ± 0.82 vs. 3.70 ± 0.73 mm) and T2 (2.68 ± 0.40 vs. 2.76 ± 0.42 mm), while the values increased again slightly up to T3 (2.74 ± 0.41 vs. 2.99 ± 0.75 mm).

CONCLUSIONS

In partially and fully compliant patients, SPT had a positive impact on PD stability and medium-term tooth preservation. In contrary to expectations, drop-out patients, PD did not return to baseline values, although PD stability was not achieved.

Treatment of periodontal diseases: Latin America and the Caribbean Consensus 2024

The prevalence of periodontitis in Latin American and Caribbean countries (LACC) drew attention to a significant public health issue exacerbated by socio-economic disparities. This consensus report, based on the European Federation of Periodontology (EFP) S3 level clinical practice guidelines, proposed a multifaceted approach to periodontal health-care. The report highlighted the critical need for holistic, population-wide health policies and underscored the lack of documented community interventions in contemporary literature. The consensus advocated for a patient-centered approach to periodontal care, with non-surgical and surgical interventions, and a long-term commitment to supportive periodontal care (SPC). It emphasized the importance of patient engagement in biofilm control by means of home-care and professional interventions for long-term periodontal health. The report also stressed that subgingival instrumentation benefits even severely compromised teeth, by significantly reducing probing depths and gingival inflammation. Moreover, it emphasized the importance of personalized, long-term SPC for maintaining oral health post-treatment, and pointed out the need to identify factors influencing patient adherence. The aim of this report was to provide actionable guidance for clinicians and policymakers, focused on improving periodontal health outcomes and quality of life in LACC.

Periodontal conditions of teeth adjacent to dental implants with or without peri-implantitis after non-surgical therapy in patients treated for periodontitis: A retrospective study

OBJECTIVES

To retrospectively assess the periodontal conditions of teeth adjacent to and contralateral to implants presenting with or without peri-implantitis, following non-surgical periodontal and peri-implant mechanical therapy.

MATERIALS AND METHODS

One hundred and one patients with existing dental implants and chronic periodontitis, who underwent non-surgical periodontal and peri-implant mechanical therapy, were included. The periodontal clinical probing depth (PPD), gingival recession (GR), and bleeding on probing (BOP) were recorded at six sites around the adjacent (Adj-) teeth and the contralateral (CL-) teeth relative to the implant. The potential factors influencing the periodontal conditions of 316 teeth were analyzed by multivariate linear regression models with generalized estimating equation methods and α = .05.

RESULTS

The PPD of Adj-teeth was significantly different from that of CL-teeth before and after non-surgical therapy when the implant was diagnosed with peri-implantitis (PI) (p < .05). The PPD of teeth was shown to be affected by neighboring implants diagnosed with peri-implantitis (β = .825 mm, p < .001), teeth adjacent to implants (β = .245 mm, p = .004), a molar tooth type (β = .435 mm, p = .019), and non-surgical therapy (β = -.522 mm, p < .001).

CONCLUSIONS

Relatively compromised periodontal conditions at Adj-teeth after non-surgical PI therapy were detected. Therefore, clinicians should be aware that non-surgical therapy may be less successful at teeth adjacent to implants with PI.

Residual vertical defects: risk of disease progression, retreatment rates, and cost: a retrospective analysis

OBJECTIVES

This study aimed to explore the relationship between Radiographic Residual Vertical Defects (RVDs) and the progression of periodontitis in patients undergoing periodontal maintenance therapy (PMT).

MATERIALS AND METHODS

Teeth with RVDs were compared to the same contralateral teeth in the same patient. The study investigated the effect of smoking, diabetes, compliance, disease Stage, and Grade, baseline probing depth (PD), periodontal risk score (PRS), baseline pocket closure (PC) (≤ 4 mm), and tooth mobility on disease progression. We calculated the need for retreatment during PMT and its associated cost. Generalized estimation equations and linear and multilevel logistic regression analyses were employed for data analysis.

RESULTS

Each group had 139 teeth, accounting for 80 patients. Although the group with RVDs had similar PD reduction compared to the control teeth, the prevalence of PC at the last follow-up was reduced to half in the RVDs group (odds ratio OR = 0.5; p-value = 0.028), regardless of PC status at the baseline. RVDs were also significant predictors of tooth loss due to periodontitis (TLP), with an OR of 2.28 (p = 0.043). Patients with diabetes, Stage IV, higher mobility, and higher PRS scores had a higher risk of tooth loss due to periodontitis (OR = 4.71, 3.84, 3.64, and 5.97, respectively (P < 0.01). Incidences of sites requiring retreatment were similar in both groups, but the cost of treatment was 30% higher for teeth with RVDs. Grade C had the most significant influence on receiving retreatments (OR = 18.8, p = 0.005).

CONCLUSION

Teeth with RVDs represent a risk indicator for tooth loss compared to identical contralateral teeth with similar PD in the same patient. Teeth with RVD had more risk of pocket opening during follow-up.

CLINICAL RELEVANCE

While teeth with RVDs can be maintained long-term, they have twice the risk of pocket opening and tooth loss due to periodontitis during follow-up. Patients with systemic and local risk factors need to be monitored closely as they are at the highest risk of losing teeth with RVDs. The increased cost of retreatment for teeth with RVDs also has implications in terms of retention versus extraction and replacement.

The Bloody Crossroads: Interactions between Periodontitis and Hematologic Diseases

Periodontitis is a common oral condition that can have a significant impact on the overall health of the body. In recent years, attention has been paid to potential relationships between periodontitis and various hematological disorders. This publication aims to present information available in the literature on this relationship, focusing on examples of red blood cell disorders (such as aplastic anemia and sickle cell anemia) and white blood cell disorders (such as cyclic neutropenia, maladaptive trained immunity, clonal hematopoiesis, leukemia, and multiple myeloma). Understanding these associations can help physicians and dentists better diagnose, monitor, and treat patients associated with both groups of conditions, highlighting the need for interdisciplinary care for patients with oral disorders and hematologic diseases.

Influence of residual pockets on periodontal tooth loss: A retrospective analysis

BACKGROUND

Individuals enrolled in supportive periodontal therapy (SPT) can still present with tooth loss due to periodontitis (TLP). There is limited evidence on the influence of residual pockets (RPc) and a defined "threshold" at which a patient's profile is set to be at high risk for TLP in the literature. Therefore, this study aimed to assess the influence of RPc on TLP and determine the prognostic performance of RPc compared to the staging and grading of periodontitis on TLP risk.

METHODS

Clinical data from 168 patients (3869 teeth) treated for periodontitis and receiving SPT for at least 10 years were evaluated in this retrospective study. TLP and the percentage of sites with RPc ≥ 5 mm or ≥6 mm per patient were collected. The prognostic performance of RPc was compared to the staging and grading of the disease on TLP using a multilevel Cox proportional hazard regression model.

RESULTS

Over a median follow-up of 25 years, 13.7% of teeth were lost, 4.6% of which were due to periodontitis. Most patients with TLP had ≥1 site with RPc ≥5 mm (90.8%) or ≥6 mm (77.6%). Multivariate multilevel Cox regression revealed that patients with >15% of sites with RPc ≥5 mm had a hazard ratio of 2.34, and grade C had a hazard ratio of 4.6 for TLP compared to RPc ≤4 mm/grade A. Grading exhibited the best discrimination and model fit.

CONCLUSION

Patients with RPc ≥5 mm at >15% of the sites are at risk for tooth loss. Grading and RPc ≥5 mm displayed very good predictive capability of TLP.

Periodontal Health among Individuals with Intellectual Disabilities Living in a Saudi Institutional Rehabilitation Centre

The aim of this study was to explore periodontal health among intellectually disabled individuals living in an institutional rehabilitation centre in the Al-Baha Region of Saudi Arabia. A cross-sectional study was conducted from November 2023 to January 2024. Clinical oral examinations were carried out using the World Health Organization criteria for bleeding sites and the presence of periodontal pockets. Simplified oral hygiene and community periodontal indices were employed to evaluate participants' oral health. A total of 89 participants, comprising both males and females with intellectual disabilities, were included in this study. Gender, severity of intellectual disability, type of additional physical disability, tooth brushing habits and oral hygiene status were significantly associated with the presence of periodontal disease. Additionally, poor oral hygiene, not brushing teeth and periodontal pockets of 4-5 mm and 6 mm or more were significantly more prevalent among individuals with severe and moderate intellectual disabilities (p = 0.001, p = 0.001, p = 0.001 and p = 0.001, respectively). The prevalence of periodontal disease among the studied population was 54%. The odds of having periodontal disease were significantly higher in the severe intellectual disability group compared to the mild intellectual disability group (OR = 2.328, 95% CI = 1.430-3.631, p = 0.03). It was also found that intellectually disabled participants with additional physical disabilities suffered more from periodontal disease than those without additional physical disabilities (OR = 0.971, 95% CI = 0.235-4.023, p = 0.025). Overall, individuals with intellectual disabilities had a significant demand for periodontal care. This study highlighted the need for more organised preventive programmes for individuals with intellectual disabilities. Dentists should be vigilant about improving periodontal health, focus on preventive programmes and provide comprehensive dental care with an emphasis on periodic recall and monitoring.

A critical look at outcome measures: Comparison between four dental research journals by use of a hierarchical model

AIM

To assess the status quo of outcome measures used in treatment studies in Endodontics, and potentially identify strategies for improvement, by (i) systematically assessing the outcome measures using a conceptual model and (ii) comparing these with measures used in corresponding studies in the adjacent fields.

METHODOLOGY

The International Endodontic Journal, Caries Research, The Journal of Clinical Periodontology and The Journal of Oral & Facial Pain and Headache were selected to cover four adjacent dental disciplines. In each journal, the 50 most recent consecutive publications fulfilling inclusion criteria were included. A hierarchical model for diagnostic imaging studies was modified to assess studies related to treatment. The model comprised six levels, with technical as the lowest level and societal as the highest. Extracted data included study origin, study type, and identified outcome measures. Fisher's Exact Tests with Bonferroni corrections compared studies. p < .05 was considered statistically significant.

RESULTS

Amongst 756 publications, the 200 most recent studies matching the inclusion criteria were identified. Less than half (36.5%) assessed the clinical, patient, or societal aspects of treatment; 10.0% in International Endodontic Journal, 28.0% in Caries Research, 38.0% in Journal of Clinical Periodontology, and 70.0% in Journal of Oral & Facial Pain and Headache (p < .001).

CONCLUSIONS

According to included publications, research on treatment within the endodontic field is mainly focusing on technical and biological outcomes. The benefits of patients and society were less frequently examined than in corresponding journals in adjacent disciplines. When designing studies, including higher-level outcomes should be considered.

Periodontitis stage and grade modifies the benefit of regular supportive periodontal care in terms of need for retreatment and mean cumulative cost

AIM

This study aimed to characterize the periodontal breakdown during supportive periodontal care (SPC) and to quantify the corresponding cost-effectiveness of periodontal therapy.

MATERIALS AND METHODS

Data were obtained from charts of patients who received active periodontal therapy (APT) with a minimum follow-up of ≥10 years. Analysis was done to identify factors associated with the incidence of additional sub-gingival instrumentation (SGI) and/or surgery (SUR) during SPC and mean cumulative cost of recurrence was calculated. All relevant data were collected.

RESULTS

In all, 442 patients were included. Over the follow-up period, 62% of Stage I and II patients and 72% of Stage III and IV patients required further treatment following the APT; 56.5% of SGI patients and 78.6% of SUR patients received a second intervention. SUR patients received more SUR during the follow-up period (p = .035). Stage III and IV patients received more SUR during SPC than Stage I and II patients (p = .001). Grade C patients received more SUR during the follow-up period (p < .05). During the 5-year period preceding retreatment, the mean SPC visits were lower for patients who did not require retreatment (p < .001). Risk factors such as regularity of maintenance, smoking and diabetes were related to a higher chance of receiving SUR during the follow-up period (p < .05). The mean cumulative costs indicated less recurrence cost for compliers in Stage III and IV or Grade B and C but not for those in Stage I and II or Grade A.

CONCLUSIONS

The risk of relapse in the maintenance population may be correlated with higher stage and grade, patient compliance, modifiable risk factors and the nature of the treatment provided during APT. The total cost of treatment of recurrences was lower for compliers in Stage III/IV and Grade B/C compared with erratic compliers with the same severity and risk.

Periodontitis in young individuals: Important factors for disease progression

AIM

To investigate the progression of periodontitis in young individuals and identify factors that contribute to progression rate and whether periodontitis stage and grade have an impact on disease progression.

MATERIALS AND METHODS

This retrospective cohort study was based on patients younger than 36 years at two periodontal clinics between 2003 and 2009. At least 10 years later, a clinical and radiographic examination was performed on 215 patients. The marginal bone loss between baseline and follow-up for the tooth with the most severe bone loss at follow-up was estimated by radiographic measurements. Linear regression analysis was used to investigate the influence of potential risk indicators on periodontitis progression.

RESULTS

Most patients (83%) were classified as periodontitis stage III at baseline. At follow-up, 70% of these patients remained in stage III. The frequency of patients with grade C decreased from 79% to 17% at follow-up. The median (Q25%; Q75%) of the longitudinal marginal bone loss was 0.5 mm (0.0; 2.0). High bleeding on probing (BOP) index at baseline, smoking and interruption of periodontal treatment were found to significantly increase longitudinal bone loss.

CONCLUSIONS

High levels of BOP at baseline, smoking and interruption of periodontal treatment increased the risk of marginal bone loss. The stage and grade at baseline had no significant impact on disease progression.

Identifying predictors of tooth loss using a rule-based machine learning approach: A retrospective study at university-setting clinics

BACKGROUND

This study aimed to identify predictors associated with tooth loss in a large periodontitis patient cohort in the university setting using the machine learning approach.

METHODS

Information on periodontitis patients and 18 factors identified at the initial visit was extracted from electronic health records. A two-step machine learning pipeline was proposed to develop the tooth loss prediction model. The primary outcome is tooth loss count. The prediction model was built on significant factors (single or combination) selected by the RuleFit algorithm, and these factors were further adopted by the count regression model. Model performance was evaluated by root-mean-squared error (RMSE). Associations between predictors and tooth loss were also assessed by a classical statistical approach to validate the performance of the machine learning model.

RESULTS

In total, 7840 patients were included. The machine learning model predicting tooth loss count achieved RMSE of 2.71. Age, smoking, frequency of brushing, frequency of flossing, periodontal diagnosis, bleeding on probing percentage, number of missing teeth at baseline, and tooth mobility were associated with tooth loss in both machine learning and classical statistical models.

CONCLUSION

The two-step machine learning pipeline is feasible to predict tooth loss in periodontitis patients. Compared to classical statistical methods, this rule-based machine learning approach improves model explainability. However, the model's generalizability needs to be further validated by external datasets.

Risk factors for tooth loss and progression of periodontitis in patients undergoing periodontal maintenance therapy

AIM

The aim of this study was to investigate patient- and tooth-level factors that may predict tooth loss and periodontitis progression in patients who have undergone at least 5 years of periodontal maintenance.

MATERIALS AND METHODS

In this retrospective cohort study, 135 patients were examined after active periodontal therapy (APT) and periodontal maintenance for 5.09-8.65 years (mean 6.16 ± 0.74 years). Regression models were applied to identify risk factors associated with tooth loss and disease progression.

RESULTS

Stage IV periodontitis (incidence rate ratio [IRR] = 4.61; 95% confidence interval, CI [2.97-7.18], p < .001), the presence of ≥5 sites with probing pocket depth (PPD) ≥5 mm at the end of APT (IRR = 2.04; 95% CI [1.32-3.20], p < .01), and residual PPD ≥7 mm at the end of APT (odds ratio [OR] = 3.01; 95% CI [1.14-7.94], p < .05) were risk factors for tooth loss. Residual PPDs of 5 mm (OR = 2.02; 95% CI [1.20-3.40], p < .01) and 6 mm (OR = 2.41; 95% CI [1.22-4.76], p < .05) at the end of APT were risk factors for disease progression. Above 3 mm, each 1 mm increase in maximum PPD/clinical attachment loss was associated with an increased risk of tooth loss and disease progression.

CONCLUSIONS

Stage IV periodontitis is associated with an increased risk of tooth loss. Teeth with PPD ≥5 mm at the end of APT are at risk of periodontitis progression or tooth loss.

Prevalence, extent, and severity of periodontitis among Australian older adults: Comparison of two generations

BACKGROUND

Chronic periodontitis is highly prevalent among older adults. The study aimed to compare periodontal disease among Australian older adults in two generations. We hypothesized that the prevalence and severity of periodontitis would decrease from the previous generation to the recent generation.

METHODS

Data were obtained from the South Australian Dental Longitudinal Study (SADLS) in 1991 to 1992 (SADLS I) and 2013 to 2014 (SADLS II); population-based longitudinal surveys of Australian older adults aged ≥60 years. American Academy of Periodontology, the US Centers for Disease Control and Prevention (AAP/CDC), and the 2018 European Federation of Periodontology (EFP/AAP) classification case definitions were used to define and calculate prevalence of chronic periodontitis. Multivariable log-Poisson regression models were used to identify risk indicators for severe periodontitis after adjusting for other covariates.

RESULTS

There were a total of 801 and 355 participants that underwent a periodontal exam in SADLS I and II, respectively. The prevalence of severe periodontitis was higher in the recent generation (88% and 56%) than the previous generation (75% and 46.7%) under the CDC/AAP and EFP/AAP case definitions, respectively. The mean number of missing teeth was lower in the recent generation (6) than the previous generation (13). The prevalence ratio of severe periodontitis was around two times higher in the younger age group, men, those not born in Australia, and current smokers across both generations.

CONCLUSIONS

Our findings indicated that the recent generation of older adults has higher prevalence and severity of chronic periodontitis than the previous generation. Our findings indicated that aging, being male, born overseas, low household income, no dental insurance, and being a current smoker are significant risk factors associated with severe periodontitis among older Australians.