Modulation of the host response in periodontal therapy

Insights into Intra Periodontal Pocket Pathogenesis, Treatment, In Vitro-In Vivo Models, Products and Patents, Challenges and Opportunity

Periodontal disease is a multifactorial pathogenic condition involving microbial infection, inflammation, and various systemic complications. Here, a systematic and comprehensive review discussing key-points such as the pros and cons of conventional methods, new advancements, challenges, patents and products, and future prospects is presented. A systematic review process was adopted here by using the following keywords: periodontal diseases, pathogenesis, models, patents, challenges, recent developments, and 3-D printing scaffolds. Search engines used were "google scholar", "web of science", "scopus", and "pubmed", along with textbooks published over the last few decades. A thorough study of the published data rendered an accurate and deep understanding of periodontal diseases, the gap of research so far, and future opportunities. Formulation scientists and doctors need to be interconnected for a better understanding of the disease to prescribe a quality product. Moreover, prime challenges (such as a lack of a vital testing model, scarcity of clinical and preclinical data, products allowing for high drug access to deeper tissue regions for prolonged residence, lack of an international monitoring body, lack of 4D or time controlled scaffolds, and lack of successful AI based tools) exist that must be addressed for designing new quality products. Generally, several products have been commercialized to treat periodontal diseases with certain limitations. Various strategic approaches have been attempted to target certain delivery regions, maximize residence time, improve efficacy, and reduce toxicity. Conclusively, the current review summarizes valuable information for researchers and healthcare professional to treat a wide range of periodontal diseases.

Upper gastrointestinal tract microbiota with oral origin in relation to oesophageal squamous cell carcinoma

Introduction: Poor oral hygiene is linked to high risks of many systemic diseases, including cancers. Oral dysbiosis is closely associated with poor oral hygiene, causing tooth loss, gingivitis, and periodontitis. We provide a summary of studies and discuss the risk factors for oesophageal squamous cell carcinoma (ESCC) from a microbial perspective in this review.Methods: A literature search of studies published before December 31, 2022 from PubMed, Web of Science, and The Cochrane Library was performed. The search strategies included the following keywords: (1) oral care, oral health, oral hygiene, dental health, dental hygiene, tooth loss, teeth loss, tooth absence, missing teeth, edentulism, tooth brushing, mouthwash, and tooth cleaning; (2) esophageal, esophagus, oesophagus, and oesophageal; (3) cancer, carcinoma, tumor, and neoplasm.Discussion: Poor oral health, indicated by infrequent tooth brushing, chronic periodontitis, and tooth loss, has been associated with an increased risk of squamous dysplasia and ESCC. Oral microbial diversity and composition are profoundly dysregulated during oesophageal tumorigenesis. Similar to the oral microbiota, the oesophageal microbiota varies distinctly in multiple bacterial taxa in ESCC and gastric cardia adenocarcinoma, both of which have high co-occurrence rates in the "Oesophageal Cancer Belt". In addition, the potential roles of oncogenic viruses in ESCC have also been discussed. We also briefly explore the potential mechanisms underlying the tumor-promoting role of dysregulated microbiota for the development of therapeutic targeting strategies.Conclusion: Poor oral health is an established risk indicator of ESCC. The dysbiosis of microbiota in upper gastrointestinal tract that highly resembles the oral microbial ecosystem but with distinct features at individual sites contributes to the development and progression of ESCC.

Notopterol Inhibits the NF-κB Pathway and Activates the PI3K/Akt/Nrf2 Pathway in Periodontal Tissue

Notopterol, an active component isolated from the traditional Chinese medicine Notopterygium incisum Ting ex H.T. Chang, exerts anti-inflammatory activity in rheumatoid arthritis. However, its roles in suppression of inflammatory insults and halting progression of tissue destruction in periodontitis remain elusive. In this study, we reveal that notopterol can inhibit osteoclastogenesis, thereby limiting alveolar bone loss in vivo. In vitro results demonstrated that notopterol administration inhibited synthesis of inflammatory mediators such as IL-1β, IL-32, and IL-8 in LPS-stimulated human gingival fibroblasts. Mechanistically, notopterol inhibits activation of the NF-κB signaling pathway, which is considered a prototypical proinflammatory signaling pathway. RNA sequencing data revealed that notopterol activates the PI3K/protein kinase B (Akt)/NF-E2-related factor 2 (Nrf2) signaling pathway in LPS-stimulated human gingival fibroblasts, a phenomenon validated via Western blot assay. Additionally, notopterol treatment suppressed reactive oxygen species levels by upregulating the expression of antioxidant genes, including heme oxygenase 1 (HO-1), NAD(P)H quinone oxidoreductase 1 (NQO1), catalase (CAT), and glutathione reductase (GSR), indicating that notopterol confers protection against oxidative stress. Notably, inhibition of Akt activity by the potent inhibitor, MK-2206, partially attenuated both anti-inflammatory and antioxidant effects of notopterol. Collectively, these results raise the possibility that notopterol relieves periodontal inflammation by suppressing and activating the NF-κB and PI3K/AKT/Nrf2 signaling pathways in periodontal tissue, respectively, suggesting its potential as an efficacious treatment therapy for periodontitis.

Correlation of Serum and Gingival Crevicular Fluid Levels of Caspase-3 and Milk Fat Globule-Epidermal Growth Factor 8 on Gingival Health

AIM

This study aimed to estimate and correlate the serum and gingival crevicular fluid (GCF) levels of caspase-3 and milk fat globule-epidermal growth factor 8 (MFG-E8) in healthy, gingivitis and generalised chronic periodontitis subjects.

MATERIALS AND METHODS

A total of 24 subjects were selected and divided into three groups. After recording the periodontal parameters (plaque index (PI), modified gingival index (MGI), probing depth (PD) and clinical attachment level (CAL)), the serum and GCF samples were collected and the levels of caspase-3 and MFG-E8 were estimated using enzyme-linked immunoassay (ELISA).

RESULTS

The mean values of PI, MGI, PD and CALs were significantly higher in group III when compared to group II and group I. The mean value of serum and GCF caspase-3 increased with increasing disease severity, whereas the mean serum and GCF values of MFG-E8 decreased with increasing severity of disease. Spearman's correlation showed a strong positive correlation between the serum and GCF levels of caspase-3 and periodontal parameters, whereas serum and GCF levels of MFG-E8 showed a strong negative correlation with the periodontal parameters.

CONCLUSION

The findings of this study are suggestive that the serum and GCF levels of caspase-3 and MFG-E8 could serve as a potential biomarker for the role of apoptosis in periodontal disease. However, further studies are required to explore the mechanism and understand the relationship between these apoptotic markers and periodontitis.

Systemic treatment with alpha-tocopherol and/or sodium selenite decreases the progression of experimental periodontitis

OBJECTIVE

To investigate the effects of sodium selenite (Se) and/or α-tocopherol (αT) applications on the alveolar bone loss (ABL), the number of gingival collagen fibers, inducible nitric oxide synthase (iNOS)+ and CD95+ cell numbers, and serum cytokine concentrations in experimental periodontitis in rats.

MATERIALS AND METHODS

Forty Sprague Dawley rats were divided into four groups of ten as follows: group A: Se group, group B: αT group, group C: Se and αT combined group, and group D: control group (intraperitoneal (IP) saline injection applied). Using the image analysis method in the connective tissue under the connective epithelium, the numbers of iNOS, CD95 positive cells, and collagen fibers were counted. ELISA kits were used to test the concentrations of serum interleukin (IL)-1β, IL-6, and IL-4.

RESULTS

The combination of Se and αT (group C) suppressed ABL compared with the control group (group D) (P < 0.05). In group A (Se), the number of iNOS+ cells was smaller than in group D (P < 0.05).

CONCLUSION

Se has been concluded to inhibit inflammation of the gum due to iNOS. Se and αT can have a remarkable important role in preventing alveolar bone loss, and particularly in combination.

CLINICAL RELEVANCE

Se and/or αT application may be useful in preventing the destruction of periodontal tissue and treatment of periodontal disease.

Low-intensity Pulsed Ultrasound regulates alveolar bone homeostasis in experimental Periodontitis by diminishing Oxidative Stress

Periodontitis is a widespread oral disease that results in the loss of alveolar bone. Low-intensity pulsed ultrasound (LIPUS), which is a new therapeutic option, promotes alveolar bone regeneration in periodontal bone injury models. This study investigated the protective effect of LIPUS on oxidative stress in periodontitis and the mechanism underlying this process.

Methods: An experimental periodontitis model was induced by administering a ligature. Immunohistochemistry was performed to detect the expression levels of oxidative stress, osteogenic, and osteoclastogenic markers in vivo. Cell viability and osteogenic differentiation were analyzed using the Cell Counting Kit-8, alkaline phosphatase, and Alizarin Red staining assays. A reactive oxygen species assay kit, lipid peroxidation MDA assay kit, and western blotting were used to determine oxidative stress status in vitro. To verify the role of nuclear factor erythroid 2-related factor 2 (Nrf2), an oxidative regulator, during LIPUS treatment, the siRNA technique and Nrf2^-/- mice were used. The PI3K/Akt inhibitor LY294002 was utilized to identify the effects of the PI3K-Akt/Nrf2 signaling pathway.

Results: Alveolar bone resorption, which was experimentally induced by periodontitis in vivo, was alleviated by LIPUS via activation of Nrf2. Oxidative stress, induced via H₂O₂ treatment in vitro, inhibited cell viability and suppressed osteogenic differentiation. These effects were also alleviated by LIPUS treatment via Nrf2 activation. Nrf2 silencing blocked the antioxidant effect of LIPUS by diminishing heme oxygenase-1 expression. Nrf2^-/- mice were susceptible to ligature-induced periodontitis, and the protective effect of LIPUS on alveolar bone dysfunction was weaker in these mice. Activation of Nrf2 by LIPUS was accompanied by activation of the PI3K/Akt pathway. The oxidative defense function of LIPUS was inhibited by exposure to LY294002 in vitro.

Conclusions: These results demonstrated that LIPUS regulates alveolar bone homeostasis in periodontitis by attenuating oxidative stress via the regulation of PI3K-Akt/Nrf2 signaling. Thus, Nrf2 plays a pivotal role in the protective effect exerted by LIPUS against ligature-induced experimental periodontitis.

Clinicomicrobiological evaluation of the efficacy of local delivery of moxifloxacin and ibuprofen gel as an adjunct to scaling and root planing in chronic periodontitis patients

Aims:

To evaluate the clinical and microbiological effects of local drug delivery of moxifloxacin and ibuprofen gel as an adjunct to conventional periodontal therapy in chronic periodontitis patients.

Subjects and Methods:

Twenty patients with moderate-to-severe chronic generalized periodontitis with probing pocket depth (PPD) of ≥5 mm and <8 mm were randomly assigned to one of the following two treatment modalities: scaling and root planing (SRP) group and moxifloxacin and ibuprofen combination gel as an adjunct to SRP group. Clinical parameters include plaque index (PI), gingival index (GI), probing depths and clinical attachment level (CAL) that were recorded at baseline and 1 and 3 months after the treatment, and microbiologic assessment was done using dark-field microscopy.

Results:

A statistically significant difference in mean PI and GI scores and reduction in PPD and gain in CAL were observed at different study intervals with greater difference in the test group. On microbiological examination, the percentage of cocci increased, while a statistically significant decrease in the mean percentage of bacilli and spirochetes was observed in both groups at given intervals. In-vitro dissolution showed controlled release of both the drugs.

Conclusions:

Among the two treatment modalities, treatment with moxifloxacin and ibuprofen local delivery as an adjunct to SRP gave superior results in clinical and microbiological parameters compared to SRP group.

The relationship between oral hygiene-related self-efficacy, general self-efficacy and daily plaque control

OBJECTIVES

To assess validity and reliability of Turkish oral hygiene-related self-efficacy (OHSE) scale, and the scores of general self-efficacy (GSE) and OHSE in the patients with gingivitis and chronic periodontitis (CP). Additionally, the effect of motivation and oral hygiene instructions on the OHSE scores and plaque index (PI) was also aimed.

MATERIALS AND METHODS

GSE and OHSE scores were obtained from 210 patients with gingivitis and CP (Group A). After determination of "cut-off" values on OHSE scores, patients with OHSE scores <30 (OHSE-low) and ≥50 (OHSE-high) were included in Group B (gingivitis, N = 25; CP, N = 27). PI values were determined, and motivation and oral hygiene instructions were performed in Group B at baseline. PI measurements and OHSE questionnaire were repeated at 1 and 3 months.

RESULTS

The intraclass reliability coefficient and Cronbach's alpha for Turkish translation of OHSE scale were 0.920 and 0.911. OHSE scores significantly correlated with GSE scores and smokers had lower OHSE scores than those of non-smokers in patients (n = 210). In both gingivitis and CP groups, OHSE scores increased and PI values decreased at 3 months. PI values were lower in gingivitis and CP groups with OHSE-high scores compared to patients with OHSE-low scores at 3 months.

CONCLUSIONS

Within the limitations of this study, it seems that Turkish version of OHSE questionnaire is reliable and valid. Patients with OHSE-low scores in both gingivitis and CP groups were less successful in performing daily plaque control, compared to patients with OHSE-high scores.

Metformin prevents against oxidative stress-induced senescence in human periodontal ligament cells

Periodontitis is a chronic infectious disease involving periodontal tissues. Periodontal ligament cells (PDLCs) play an important role in the regeneration of periodontal tissue. However, senescent PDLCs have an impeded regenerative potential. Metformin has been reported to prevent senescence at both the cellular and individual levels. The objectives of the present study were to evaluate the effects of metformin on cellular senescence in human PDLCs (hPDLCs) under oxidative stress. hPDLCs were pretreated with metformin, followed by H₂O₂ exposure. The cell viability, oxidative damage, cellular senescence and osteogenic potential were detected. To inhibit autophagy, hPDLCs were treated with 3-methyladenine before metformin treatment. The present study revealed that H₂O₂ exposure inhibits proliferation, increased lysosomal β-galactosidase activity, augments reactive oxidative species (ROS) accumulation, elevates the oxidative damage, stimulates the expression of senescence-related genes and impedes the activity of the osteogenic differentiation of hPDLCs. Metformin pretreatment could partly reverse the detrimental influences of H₂O₂ on hPDLCs. Moreover, metformin could stimulate autophagy, whereas the inhibition of autophagy with 3-methyladenine reversed the anti-senescence effects of metformin on hPDLCs under oxidative stress. The present study manifested that metformin could alleviate oxidative stress-induced senescence via stimulating autophagy and could partially recover the osteogenic potential of hPDLCs, possibly providing a reference for the discovery of periodontal treatment from the perspective of antisenescence.

The comparative evaluation of 1% alendronate gel as local drug delivery system in chronic periodontitis in smokers and non smokers: Randomized clinical trial

INTRODUCTION

Periodontitis is a progressive disease of microbial origin involving the loss of supporting tissues of the teeth resulting from host inflammatory and immunologic reactions. The standard approach to the prevention and treatment of periodontal diseases for a number of years has been mechanical therapy and if required surgical intervention Researcher thought of creating a treatment modality where by altering the host response, the destructive host mechanisms could be interfered affecting the final outcome of the disease process.

AIM

The present study aims to explore the efficacy of local delivery of a 1% Alendronate (ALN) gel as an adjunct to scaling and root planing (SRP) for the treatment of infrabony periodontal pockets in smokers and non-smoker with Chronic Periodontitis.

MATERIALS AND METHOD

60 infrabony periodontal pockets in patients with chronic periodontitis between the age group of 30-50 years were selected. The study consisted of 2 groups smoker and nonsmoker. A gel based drug delivery system of Alendronate was formulated. 0.1 ml alendronate gel and 0.1 ml placebo gel was placed at the experimental and control sites respectively following root planing. Clinical and radiographic parameters were recorded at baseline, three months and six months.

RESULTS

Alendronate was effective in improving clinical and radiographic parameters compared to placebo. Alendronate showed better result in non smoker group when compared with smoker group.

CONCLUSION

This Study showed improvements in clinical parameters both at the control and experimental sites. However, the experimental sites (Alendronate) showed greater improvement as compared to the control sites (Placebo). A significant gain in alveolar crest height and defect fill was measured radiographically at non smoker Alendronate group.

Effects of Monolaurin on Oral Microbe-Host Transcriptome and Metabolome

The aim of this in vitro study was to evaluate the effects of monolaurin against Aggregatibacter actinomycetemcomitans (Aa) and determine their effects on the host transcriptome and metabolome, using an oral cell/bacteria co-culture dual-chamber model to mimic the human periodontium. For this, the Aa, was applied to cross the monolayer of epithelial keratinocytes (OBA-9) to reach the fibroblasts layer (HGF-1) in the basal chamber. The Monolaurin treatments (25 or 50 μM) were added immediately after the inoculation of the dual-chamber with Aa. After 24 h, the transcriptional factors and metabolites produced were quantified in the remaining cell layers (insert and basal chamber) and in supernatant released from the cells. The genes IL-1α, IL-6, IL-18, and TNF analyzed in HGF-1 concentrations showed a decreased expression when treated with both concentration of Monolaurin. In keratinocytes, the genes IL-6, IL-18, and TNF presented a higher expression and the expression of IL-1α decreased when treated with the two cited concentrations. The production of glycerol and pyruvic acid increased, and the 2-deoxytetronic acid NIST, 4-aminobutyric acid, pinitol and glyceric acid, presented lower concentrations because of the treatment with 25 and/or 50 μM of Monolaurin. Use of monolaurin modulated the immune response and metabolite production when administered for 24 h in a dual-chamber model inoculated with A. actinomycetemcomitans. In summary, this study indicates that monolaurin had antimicrobial activity and modulated the host immune response and metabolite production when administered for 24 h in a dual-chamber model inoculated with A. actinomycetemcomitans.

Association between oral health and colorectal adenoma in a screening population

Although periodontal disease and gastrointestinal tract health are closely associated, few studies have investigated whether periodontitis is a risk factor for colorectal adenoma. The aim of this study was to investigate whether there is an association between periodontitis and the risk of colorectal adenoma in asymptomatic healthy people.From January 2013 to October 2015, we retrospectively enrolled 42,871 patients who underwent health screening at Kangbuk Samsung Hospital in South Korea. Demographic and clinical data were collected before colonoscopy. We calculated the odds ratio (OR) for adenoma in these patients.The median age was 39.3 ± 8.7 years and 70.4% of the patients were men; 32.5% had a body mass index (BMI) 25.0 kg/m. The frequency of adenoma was 12% (n = 5136). A higher risk of adenoma was associated with the following factors: BMI 25.0 kg/m (OR 1.51, 95% confidence interval [CI]: 1.42-1.61), current smoker (OR 1.51, 95% CI: 1.42-1.61), former smoker (OR 1.28, 95% CI: 1.19-1.37), periodontitis (OR 1.95, 95% CI: 1.82-2.0), moderate alcohol intake (OR 1.8, 95% CI: 1.69-1.93), and heavy alcohol intake (OR 2.67, 95% CI: 2.24-3.18).Being male or a former or current smoker, alcohol intake above the moderate level, and periodontitis increase the risk of colorectal adenoma. These findings suggest that controlling oral disease is important to the prevention and management of colorectal adenoma. The findings of this study could be applied to risk stratification and colorectal cancer prevention programs, including screening guidelines.

Evaluation of oral hygiene self-efficacy, knowledge, and motivation among young adults of rural-based tamilian population: A prospective cohort study

Background:

Oral hygiene is the most essential factor in the prevention and therapy of many diseases, especially the periodontal disease. The aim of this study was to evaluate the oral hygiene-related knowledge, self-efficacy, and motivation of the young adults of rural-based Tamilian population, with their current oral hygiene practices to assess the effect of patient motivation after initial periodontal therapy.

Materials and Methods:

A hundred patients filled out questionnaires based on their oral hygiene-related knowledge. Plaque index, gingival index, and gingival bleeding index were recorded and correlated with their questionnaire knowledge. Initial periodontal therapy and motivation were done to all patients. After 6 months, oral health status was evaluated again.

Results:

There was a lower correlation value with insignificant P value between the questionnaire score and plaque and gingival index score, (r = 0.125, 0.166). However, the correlation between questionnaire score and modified papilla bleeding index score was high (r = 0.254) with significant (P = 0.011). After 6 months following the initial periodontal treatment, significant decrease in all the three indices scores was noted with significant (P < 0.001).

Conclusion:

Oral hygiene-related motivational approaches targeting rural young adult population has the potential to predict oral hygiene behavior and influences the clinical outcomes.

Comparative Evaluation of Two Different Ultrasonic Liquid Coolants on Dental Aerosols

INTRODUCTION

Dentists are more prone for developing infectious diseases especially related to respiratory system. The ultrasonic scaler which is a major source of dental aerosol production is most frequently used contrivance in a dental set up.

AIM

The aim of this study was to evaluate the effect of povidone iodine and chlorhexidine gluconate as an ultrasonic liquid coolant on aerosols in comparison with distilled water. The objectives of this study were to compare the potency of povidone iodine and chlorhexidine gluconate on reducing dental aerosols and quantitative assessment of microbial content of dental aerosols at right, left and behind the dental chair.

MATERIALS AND METHODS

In this study 30 subjects were selected who fulfilled the inclusion criteria and were divided into three groups. Group 1 (Control group): Ultrasonic scaling with distilled water (10 subjects), Group 2 (Test group): Ultrasonic scaling with 2% povidone iodine (10 subjects), Group 3 (Test group): Ultrasonic scaling with 0.12% chlorhexidine (10 subjects). At the baseline one blood agar plate was kept for 10 minutes in the fumigated chamber before ultrasonic scaling, thereafter three blood agar plates were kept at a distance of 0.4 meters away on either side of the patient and 2 meters behind the patient's mouth during ultrasonic scaling. Blood agar plates were kept for gravitometric settling of dental aerosols.

RESULTS

At baseline, no significant numbers of Colony-Forming Units (CFU) were detected. It is found that Group 3 (chlorhexidine gluconate) showed effective CFU reduction (27.17 ±12.5 CFU) when compared to distilled water (124.5 ± 30.08 CFU) and povidone iodine (60.43 ± 33.33 CFU). More CFU were found on blood agar plates which were kept on right side in all the three groups. The results obtained were statistically significant (p< 0.001).

CONCLUSION

Chlorhexidine gluconate is more effective in reducing dental aerosols when compared to povidone iodine and distilled water. Povidone iodine showed better CFU reduction when compared with distilled water. Hence, chlorhexidine or povidone iodine can also be used as an ultrasonic liquid coolant for reducing the number of dental aerosols during ultrasonic scaling.

Oral hygiene-related self-efficacy as a predictor of oral hygiene behaviour: a prospective cohort study

AIM

The aim of this study was to assess whether oral hygiene-related self-efficacy is correlated with current oral hygiene and might influence the outcome of oral hygiene instruction.

MATERIALS AND METHODS

Hundred and twenty-six patients filled out questionnaires about oral hygiene-related self-efficacy, general self-efficacy, oral hygiene-related knowledge and demographic variables. Plaque and gingival inflammation were measured and an individual oral hygiene plan was conducted. After 6 months, oral hygiene indices were assessed again.

RESULTS

Women had significantly higher scores in oral hygiene-related self-efficacy than men (women mean 60.40 ± 9.41; men mean 56.04 ± 11.55; p = 0.039) and oral hygiene-related self-efficacy was significantly correlated with general self-efficacy independent from the age of the patients (r = 0.3114, p = 0.0004). Higher scores in oral hygiene-related self-efficacy were significantly correlated with lower scores of gingival bleeding for non-smoking patients (r = -0.301, p = 0.0066), usage of a professional tooth cleaning within these 6 months (p = 0.0406), reappearance to the follow-up appointment (p = 0.0303), and higher goals in inter-dental cleaning plans (p = 0.0189).

CONCLUSION

Oral hygiene-related self-efficacy is an influencing factor in the oral hygiene behaviour and has the potential to predict patients' oral hygiene outcomes.

Clinical efficacy and patients' acceptance of a rubber interdental bristle. A randomized controlled trial

OBJECTIVES

Interdental cleaning is an essential component of home plaque control to prevent periodontitis and caries. There is limited data on the efficacy of commonly used metal-core interdental brushes in comparison to metal-free interdental brushes. The aim of this study was to compare a new rubber interdental bristle (Fuchs®) with a standard metal-core interdental brush (TePe®) for their impact upon gingival bleeding, plaque removal, and patient experience.

MATERIALS AND METHODS

A single-blind, prospective, randomized, and controlled clinical trial with a crossover design was used to measure plaque index (Turesky-Modified Quigley & Hein Index), bleeding index (Eastman Interdental Bleeding Index by Caton & Polson), and patient satisfaction by means of questionnaires in 39 patients. Each patient was randomly assigned with regard to the sequence of interdental product used and recalled.

RESULTS

Both groups showed statistically significant decreases of plaque after a single usage, respectively. Bleeding was statistically significantly reduced after 4 weeks, with no statistically significant differences concerning between the two tested interdental brushes. Rubber interdental bristles reached significantly higher scores with regard to patient acceptance in overall assessment and in sub-items for less pain during usage, comfort of brushing, and willingness to buy the product.

CONCLUSION

Rubber interdental bristles were similarly effective compared to the interdental brushes. In addition, rubber interdental bristles were significantly more comfortable for participants than metal-core brushes.

CLINICAL RELEVANCE

Rubber interdental bristles can be used as an alternative interdental cleaning product which may be more accepted by patients.

Tooth loss and risk of head and neck cancer: a meta-analysis

Background

Observational studies suggest an association between tooth loss and risk of head and neck cancer. However, whether tooth loss is an independent risk factor for head and neck cancer still remains controversial. The aim of this study is to assess the association between tooth loss and head and neck cancer risk.

Methods

Eligible studies were searched in PubMed and Embase databases from their inception to March 2013. A random-effects model or fixed-effects model was used to calculate the overall combined risk estimates.

Results

Eight case-control studies and one cross-sectional study involving 5,204 patients and 5,518 controls were included in the meta-analysis. The overall combined odds ratio for tooth loss and head and neck cancer was 2.00 (95% confidence interval, 1.28–3.14). Similar results yielded both in the moderate and severe tooth loss group. Sensitivity analysis based on various exclusion criteria maintained this significance with respect to head and neck cancer individually. Little evidence of publication bias was observed.

Conclusion

This meta-analysis suggests that tooth loss is associated with increased risk of head and neck cancer. This increase is probably independent of conventional head and neck cancer risk factors.

Baicalin downregulates Porphyromonas gingivalis lipopolysaccharide-upregulated IL-6 and IL-8 expression in human oral keratinocytes by negative regulation of TLR signaling

Periodontal (gum) disease is one of the main global oral health burdens and severe periodontal disease (periodontitis) is a leading cause of tooth loss in adults globally. It also increases the risk of cardiovascular disease and diabetes mellitus. Porphyromonas gingivalis lipopolysaccharide (LPS) is a key virulent attribute that significantly contributes to periodontal pathogenesis. Baicalin is a flavonoid from Scutellaria radix, an herb commonly used in traditional Chinese medicine for treating inflammatory diseases. The present study examined the modulatory effect of baicalin on P. gingivalis LPS-induced expression of IL-6 and IL-8 in human oral keratinocytes (HOKs). Cells were pre-treated with baicalin (0–80 µM) for 24 h, and subsequently treated with P. gingivalis LPS at 10 µg/ml with or without baicalin for 3 h. IL-6 and IL-8 transcripts and proteins were detected by real-time polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. The expression of nuclear factor-κB (NF-κB), p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK) proteins was analyzed by western blot. A panel of genes related to toll-like receptor (TLR) signaling was examined by PCR array. We found that baicalin significantly downregulated P. gingivalis LPS-stimulated expression of IL-6 and IL-8, and inhibited P. gingivalis LPS-activated NF-κB, p38 MAPK and JNK. Furthermore, baicalin markedly downregulated P. gingivalis LPS-induced expression of genes associated with TLR signaling. In conclusion, the present study shows that baicalin may significantly downregulate P. gingivalis LPS-upregulated expression of IL-6 and IL-8 in HOKs via negative regulation of TLR signaling.

Chemically modified tetracyclines: Novel therapeutic agents in the management of chronic periodontitis

Chronic periodontitis is a complex infection initiated by gram-negative bacteria which destroy the supporting structures of the tooth. Recently, it has been recognized that it is the host response to bacterial infection which causes greater destruction of the connective tissue elements, periodontal ligament and alveolar bone in periodontitis. This has led to the development of various host modulating approaches to target cells and their destructive mediators involved in tissue degradation. Chemically modified tetracyclines (CMTs) are derivatives of tetracycline group of drugs which lack antimicrobial action but have potent host modulating affects. They inhibit pathologically elevated matrix metal loproteinases, pro-inflammtory cytokines and other destructive mediators. Bone resorption is also suppressed due to their combined anti-proteinase and apoptotic affects on osteoblasts and osteoclasts, respectively. Development of resistant bacteria and gastrointestinal toxicity seen with parent tetracyclines is not produced by CMTs. Hence, CMTs are viewed as potential therapeutic agents in the management of chronic diseases like periodontitis that involve destruction of connective tissue and bone.

Treatment modalities and evaluation models for periodontitis

Periodontitis is the most common localized dental inflammatory disease related with several pathological conditions like inflammation of gums (gingivitis), degeneration of periodontal ligament, dental cementum and alveolar bone loss. In this perspective, the various preventive and treatment modalities, including oral hygiene, gingival irrigations, mechanical instrumentation, full mouth disinfection, host modulation and antimicrobial therapy, which are used either as adjunctive treatments or as stand-alone therapies in the non-surgical management of periodontal infections, have been discussed. Intra-pocket, sustained release systems have emerged as a novel paradigm for the future research. In this article, special consideration is given to different locally delivered anti-microbial and anti inflammatory medications which are either commercially available or are currently under consideration for Food and Drug Administration (FDA) approval. The various in vitro dissolution models and microbiological strain investigated to impersonate the infected and inflamed periodontal cavity and to predict the in vivo performance of treatment modalities have also been thrashed out. Animal models that have been employed to explore the pathology at the different stages of periodontitis and to evaluate its treatment modalities are enlightened in this proposed review.

Anticytokine therapy for periodontal diseases: Where are we now?

Periodontal destruction is initiated by bacteria that stimulate host responses leading to excess production of cytokines. Anticytokine therapy for periodontal diseases especially targets proinflammatory cytokines, that is, TNF-α, IL-1, and IL-6, because these are essential for the initiation of the inflammatory immune reaction and are produced for prolonged periods in periodontitis. This therapy aims to bind the cytokines with the receptors present on target cells such as the fibroblasts. The three basic treatment strategies are: (1) neutralization of cytokines, (2) blockage of cytokine receptors, and (3) activation of anti-inflammatory pathways, such as, immune-suppressive pathways.

This new therapy can act as a host response modulator in the control of inflammatory diseases of gums and may provide the basis for new molecular therapeutic approaches to the treatment of periodontitis.

Toll gates to periodontal host modulation and vaccine therapy

Toll-like receptors (TLRs) are central mediators of innate antimicrobial and inflammatory responses and play instructive roles in the development of the adaptive immune response. Thus when stimulated by certain agonists, TLRs serve as adjuvant receptors that link innate and adaptive immunity. However, when excessively activated or inadequately controlled during an infection, TLRs may contribute to immunopathology associated with inflammatory diseases, such as periodontitis. Moreover, certain microbial pathogens appear to exploit aspects of TLR signalling in ways that enhance their adaptive fitness. The diverse and important roles played by TLRs suggest that therapeutic manipulation of TLR signalling may have implications in the control of infection, attenuation of inflammation, and the development of vaccine adjuvants for the treatment of periodontitis. Successful application of TLR-based therapeutic modalities in periodontitis would require highly selective and precisely targeted intervention. This would in turn necessitate precise characterization of TLR signalling pathways in response to periodontal pathogens, as well as development of effective and specific agonists or antagonists of TLR function and signalling. This review summarizes the current status of TLR biology as it relates to periodontitis, and evaluates the potential of TLR-based approaches for host-modulation therapy in this oral disease.

A review of the relationship between tooth loss, periodontal disease, and cancer

Recent studies have investigated the association between periodontal disease, tooth loss, and several systemic diseases including cancer, cardiovascular disease, and preterm birth. Periodontal disease, a chronic inflammatory condition, is highly prevalent in adult populations around the world, and may be preventable. Estimates of prevalence vary between races and geographic regions, with a marked increase in the occurrence of periodontal disease with advancing age. Worldwide estimates for the prevalence of severe periodontal disease generally range from 10 to 15%. The relationship between oral health and cancer has been examined for a number of specific cancer sites. Several studies have reported associations between periodontal disease or tooth loss and risk of oral, upper gastrointestinal, lung, and pancreatic cancer in different populations. In a number of studies, these associations persisted after adjustment for major risk factors, including cigarette smoking and socioeconomic status. This review provides a summary of these findings, discusses possible biological mechanisms involved, and raises methodological issues related to studying these relationships.

Efficacy of sub-antimicrobial dose doxycycline in post-menopausal women: clinical outcomes

AIMS

To determine the clinical efficacy of a 2-year continuous sub-antimicrobial dose doxycycline (SDD; 20 mg bid) in post-menopausal, osteopenic, oestrogen-deficient women on periodontal maintenance.

MATERIALS AND METHODS

One-hundred and twenty-eight subjects were randomized to SDD (n=64) or placebo (n=64). Clinical measurements were performed at posterior interproximal sites at baseline and every 6 months during this 2-year randomized, double-blind, placebo-controlled clinical trial with adjunctive, no-cost 3-4-month periodontal maintenance. Statistical analyses of secondary outcomes from this clinical trial used Generalized Estimating Equations in primarily intent-to-treat analyses.

RESULTS

For the placebo group, 3.4% of the sites showed improvement in clinical attachment levels (CAL) and 2.7% had progressive loss in CAL; for the SDD group, 5.0% of the sites showed an improvement in CAL and 2.2% had progressive loss in CAL. This difference (2.1% of sites) was more favourable in the SDD group than in the placebo [odds ratio (OR)=0.81 [corrected] 95% confidence interval (CI): 0.67-0.97, p=0.03] in these well-maintained patients, whereas probing depths, bleeding on probing and supragingival plaque did not differ significantly between groups (p>0.2). However, in exploratory subgroup analysis of non-smokers, SDD showed reduced bleeding versus placebo (27%versus 33%; p=0.05). In protocol-adherent subjects, the odds of bleeding were 34% lower for SDD (p=0.05).

CONCLUSIONS

Analyses of secondary outcomes of this clinical trial indicated that SDD may be of benefit in reducing progressive attachment loss in post-menopausal females; additional research is needed to confirm these findings. Protocol registered at (ClinicalTrials.gov). Identifier:NCT00066027.

Accumulation of topical naproxen by cultured oral epithelium

Topically administered non-steroidal anti-inflammatory drugs (NSAIDs) inhibit periodontal bone loss, but little is known about the mechanism by which they penetrate oral epithelium. Active transporters could potentially play a role in this process. In this study, we used a cell line derived from oral epithelium to investigate a role for transporters and to characterize conditions that enhance epithelial penetration. Using fluorescence to monitor uptake, we demonstrated that SCC-25 cell monolayers transport naproxen with a Michaelis constant (K(m)) and maximum velocity (V(max)) of 164 microg/mL and 0.94 ng/min/microg protein, respectively. At steady state, the intra-cellular/extracellular concentration ratio was 3.4. Naproxen accumulation was more efficient at acidic pH than under neutral or alkaline conditions. Small proportions of glycerol, Pluronic F-127, and glucosylceramide enhanced naproxen entry. The individual and combined effects of glycerol and Pluronic F-127 were of lesser magnitude than those obtained with glucosylceramide or at pH 6.3. Thus, SCC-25 cells possess transporters for naproxen.

The Effect of Aspirin on Gingival Crevicular Fluid Levels of Inflammatory and Anti-Inflammatory Mediators in Patients With Gingivitis

BACKGROUND

Inflammatory and anti-inflammatory mediators may play a significant role in patients with gingivitis. The purpose of this study was to assess the short-term effects of the systemic administration of two different concentrations of aspirin (81 and 325 mg/day, by mouth) on clinical periodontal parameters and gingival crevicular fluid (GCF) levels of 15-epi-lipoxin A4 (15-epi-LXA4), lipoxin A4, leukotriene B4 (LTB4), prostaglandin E2 (PGE2), and interleukin (IL)-6 and -1beta in a sample of naturally occurring gingivitis patients.

METHODS

At day 0, after initial screening for entry, baseline periodontal parameters, including bleeding on probing (BOP), periodontal probing depths (PDs), and plaque index (PI) were measured, and GCF was sampled from 12 intrasulcular sites with filter paper strips for the measurement of six types of inflammatory and anti-inflammatory mediators using competitive enzyme immunoassay and enzyme-linked immunosorbent assay (prevalues). Forty-seven subjects were assigned randomly to one of three treatment groups: placebo (15 subjects); aspirin, 81 mg (16 subjects); and aspirin, 325 mg (16 subjects) once daily. On day 7, subjects were recalled for the measurement of periodontal parameters and collection of GCF samples for the measurement of six types of mediators (postvalues).

RESULTS

Changes in inflammatory and anti-inflammatory mediator levels were not statistically significant for any of the three treatment groups. However, when pre- and postvalues were compared in the subjects receiving aspirin, 325 mg, there was a negative trend in the relationship between 15-epi-LXA4 and PGE2, whereas the relationship between LTB4 and PGE2 was not as strong. This might indicate that the subjects responding to aspirin-mediated PGE2 suppression effects produced higher 15-epi-LXA4 in GCF than non-responders. No statistically significant differences in PD and PI between pre- and postvalues were found for any of the three treatment groups. However, the results demonstrated a significant increase in BOP when aspirin, 325 mg was compared to placebo (P <0.001) and aspirin, 81 mg (P = 0.001).

CONCLUSIONS

Aspirin can have an affect on BOP in naturally occurring gingivitis patients. Although most of the inflammatory mediators did not show significantly detectable changes after aspirin treatment for 7 days, the trend of aspirin-associated increases of 15-epi-LXA4 implied that this recently discovered aspirin-dependent eicosanoid may be associated with the increased incidence of BOP observed in the subjects who received aspirin therapy.

Stability of Clinical and Radiographic Results After Guided Tissue Regeneration in Infrabony Defects

BACKGROUND

The aim of this 5-year follow-up study was to evaluate clinically and radiographically the long-term results after guided tissue regeneration (GTR) therapy of infrabony defects using non-resorbable and bioabsorbable barriers.

METHODS

Thirty-one patients with periodontitis and 50 infrabony defects that had been treated using GTR were recruited. Eleven defects were treated with non-resorbable expanded polytetrafluoroethylene membranes and 39 defects with bioabsorbable barriers. At baseline and 6 and 60 +/- 3 months after surgery, clinical parameters and standardized radiographs were obtained. During surgery and 60 +/- 3 months thereafter, the distance from the cemento-enamel junction to the base of the bony defect (vertical probing bone level [PBL-V]) was measured. Bone gain was evaluated using digital subtraction radiography.

RESULTS

At 6 and 60 +/- 3 months after GTR, there was a statistically significant (P <0.001) reduction of probing depth (6 months: 4.31 +/- 1.76 mm; 60 months: 3.95 +/- 1.62 mm) and vertical clinical attachment level gains (CAL-V) (6 months: 3.34 +/- 1.66 mm; 60 months: 2.97 +/- 1.53 mm). From 6 to 60 months after GTR, three infrabony defects exhibited CAL-V loss >2 mm, and a small, statistically not significant mean CAL-V loss of 0.39 +/- 1.60 mm was observed. From baseline to 60 +/- 3 months, a significant PBL-V gain of 1.78 +/- 2.67 mm (P <0.001) and increase in bone density were observed (P = 0.003).

CONCLUSION

The CAL-V gain achieved after GTR in infrabony defects using both non-resorbable and bioabsorbable barriers was stable after 5 years in 47 of 50 defects.

Modulation of gingival fibroblast minocycline accumulation by biological mediators

Gingival fibroblasts actively accumulate tetracyclines, thereby enhancing their redistribution from blood to gingiva. Since growth factors and pro-inflammatory cytokines regulate many fibroblast activities, they could potentially enhance fibroblast minocycline accumulation. To test this hypothesis, we treated gingival fibroblast monolayers for 1 or 6 hours with platelet-derived growth factor-BB (PDGF), fibroblast growth factor-2 (FGF), transforming growth factor-beta1 (TGF), or tumor necrosis factor-alpha (TNF). Minocycline uptake was assayed at 37 degrees by a fluorescence method. All 4 factors significantly enhanced minocycline uptake (P < or = 0.008, ANOVA), primarily by increasing the affinity of transport. Treatment for 6 hours with 10 ng/mL FGF, PDGF, TGF, or TNF enhanced fibroblast minocycline uptake by 19% to 25%. Phorbol myristate acetate enhanced fibroblast minocycline uptake by 28%, suggesting that protein kinase C plays a role in up-regulating transport. These effects on transport provide a mechanism by which systemic tetracyclines could be preferentially distributed to gingival wound or inflammatory sites.

The use of surrogate variables to reflect long-term tooth survivability

Clinical parameters used to monitor periodontal patients are usually measures of the disease process. They are considered surrogate variables because changes in their status are interpreted to have an impact on the ultimate goal of periodontal therapy, which is tooth retention. However, their ability to reflect tooth survivability has been questioned because there is a lack of long-term data to validate that stable or improved surrogates result in reduced tooth loss. Therefore, to clarify the utility of employing surrogates to reflect long-term tooth retention, a number of issues related to their use are discussed in this commentary: phraseology, benefits and shortcomings, biologic credibility, and their previous successful utilization in monitoring the effects of therapy. This commentary supports the reasonableness of using surrogates to monitor periodontal status and suggests that a combination of surrogates that represent "periodontal clinical health" should be considered a true endpoint of periodontal therapy, since this outcome provides a condition conducive to tooth retention.

Effect of neutrophil apoptosis on monocytic cytokine response to Porphyromonas gingivalis lipopolysaccharide

BACKGROUND

Neutrophil apoptosis may play a critical role in the resolution of inflammation by stimulating anti-inflammatory cytokine generation from monocytes. In this study, we investigated the effect of apoptotic neutrophils on interleukin (IL)-10 and IL-1beta production from monocytes in response to Porphyromonas gingivalis lipopolysaccharide.

METHODS

Peripheral blood neutrophils from healthy individuals were isolated by sodium diatrizoate density gradient centrifugation. In order to induce apoptosis, neutrophils were cultured for 24 hours in modified Dulbecco's medium supplemented with 10% autologous serum. Cell apoptosis was quantified by Annexin V positivity and loss of CD16 expression on the cell surface. Peripheral blood mononuclear cells were isolated from the same subjects; monocytes were purified by magnetic cell sorting and cultured with or without apoptotic or fresh neutrophils. Lipopolysaccharide from Porphyromonas gingivalis was used for cell stimulation. IL-1beta and IL-10 levels in supernatants were determined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

IL-10 generation was significantly increased in monocytes cultured with apoptotic neutrophils compared to monocytes alone or cocultured with fresh neutrophils (P <0.05). IL-1beta was suppressed both in resting and lipopolysaccharide-stimulated monocytes in the presence of apoptotic neutrophils compared to monocytes alone or monocytes cultured with fresh neutrophils at all time points (P <0.05).

CONCLUSION

Neutrophil apoptosis provides a signal to monocytes, changing the phenotype of the monocyte resulting in the production of anti-inflammatory cytokines and suppression of proinflammatory cytokines in response to lipopolysaccharide.

The effect of HAART on salivary microbiota in the Women's Interagency HIV Study (WIHS)

OBJECTIVE

Study the prevalence of potentially pathogenic microorganisms in saliva of HIV-positive women in the Women's Interagency HIV Study.

STUDY DESIGN

157 HIV-positive and 31 HIV-negative women were studied. At baseline and every 6 months over 4 years, information was collected on socioeconomic and educational status, oral and systemic health, including HIV markers and antiretroviral therapy, and frequency of professional oral care utilization. Bacterial and yeast pathogenic isolates from stimulated whole saliva were tentatively identified using standard methodologies.

RESULTS

The prevalence of microorganisms in stimulated saliva of HIV-positive women was not significantly different from that of HIV-negative women. In HIV-positive women, highly active antiretroviral therapy (HAART) was independently and significantly associated with the presence of a variety of salivary bacterial species. HAART increased the risk for recovering Fusobacterium species (P < .001), enteric gram-negative rods (P < .05), Peptostreptococcus micros (P < .05), Campylobacter species (P < .0001), Eubacterium species (P < .001), and Tannerella forsythia (P < .01). In contrast, HAART led to decreased recovery rate of yeasts (Candida albicans and Candida dubliniensis) (P < .0001).

CONCLUSION

The present findings suggest that the institution of HAART promotes an increasingly pathogenic salivary microbiota, at least temporarily. Similar findings have been reported for various nonoral microbial ecosystems.

Guided Tissue Regeneration With Bioabsorbable Barriers. II. Long-Term Results in Infrabony Defects

BACKGROUND

The aim of this 5-year randomized controlled clinical trial was to evaluate the long-term results after guided tissue regeneration (GTR) therapy of infrabony defects using two bioabsorbable barriers.

METHODS

Fifteen pairs of contralateral infrabony defects in 15 patients with moderate to severe periodontitis were treated. Each patient received one polydioxanon (test: T) and one polylactide acetyltributyl citrate (control: C) barrier by random assignment. At baseline, 12, and 60 +/- 3 months after surgery clinical parameters and standardized radiographs were obtained. Vertical bone levels (PBL-V) were measured during surgery and 60 +/- 3 months later by transgingival bone sounding.

RESULTS

Thirteen patients were available for the 60-month examinations. Twelve and 60 +/- 3 months after GTR, statistically significant (P< or =0.001) vertical attachment (CAL-V) gain was found in both groups (T12: 3.5 +/- 1.5 mm; T60: 2.2 +/- 1.8 mm; C12: 4.0 +/- 0.9 mm; C60: 2.4 +/- 1.0 mm). However, from 12 to 60 months after therapy both groups experienced significant CAL-V loss (P<0.05): two defects in the test group and three in the control group had CAL-V loss >2 mm compared to the 12-month reexamination. Twelve and 60 +/- 3 months after surgery, statistically significant (P<0.05) radiographic bony fill was found in both groups (T12: 1.2 +/- 1.3 mm; T60: 1.5 +/- 2.2 mm; C12: 0.9 +/- 1.4 mm; C60: 1.0 +/- 1.6 mm). Further, 60 months after surgery significant (P<0.05) PBL-V gain was found in both groups (test: 1.8 +/- 2.3 mm; control: 2.2 +/- 1.8 mm). The study failed to show statistically significant differences between test and control regarding CAL-V and PBL-V gain 60 months after surgery.

CONCLUSION

CAL-V gain achieved after GTR therapy in infrabony defects using both bioabsorbable barriers was stable after 5 years in 21 of 26 defects (81%).

Relationship between clinical parameters and cytokine profiles in inflamed gingival tissue and serum samples from patients with chronic periodontitis

OBJECTIVE

The purpose of the present study was to assess the relation between clinical parameters and concentrations of the key (IL-1beta, TNF-alpha, IL-2, IFN-gamma, IL-4, IL-10) cytokines, important in the initiation and progression of periodontal diseases, within inflamed gingival tissues and serum samples from patients with severe chronic periodontitis.

MATERIAL AND METHODS

Twenty-five patients with severe chronic periodontitis, who had sites with probing depths (PD) > 5 mm, and 25 periodontally healthy persons were included in the study. Clinical examinations including PD, clinical attachment loss, plaque index, and bleeding index were performed before periodontal treatment. Gingival tissue biopsies were collected from one active site of each patient and from healthy individuals, and blood samples were withdrawn on the day of tissue biopsy. The concentrations of cytokines were determined by an enzyme-linked immunosorbent assay, and the relationship between their profiles in situ and in circulation with clinical parameters was analysed.

RESULTS

The concentrations of IL-1beta, TNF-alpha, IL-2, IFN-gamma were, on average, significantly higher in serum samples and gingival tissue biopsies from periodontitis patients than in healthy controls. However, serum samples from both groups showed high individual variability of cytokine profiles, and no association between cytokine concentrations and clinical parameters of periodontitis was found. On the contrary, the levels of IL-4 and IL-10 in both kinds of samples obtained from patients and controls were generally low or even undetectable, and remained, on average, on the same level. However, the frequency of IL-4 (88% positive samples) and IL-10 (72%) was much higher in healthy gingival tissues. High concentrations of TNF-alpha, IFN-gamma and IL-2 and, especially, a high ratio of IL-1beta/IL-10 and TNF-alpha/IL-4 found in tissue biopsies from periodontitis patients, strongly correlated with the severity of periodontitis.

CONCLUSION

These results indicate that high variability of cytokine concentrations and low frequency of their detection in serum samples from periodontitis patients make these determinations useless for the detection of disease presence and/or its severity. In contrast, high absolute levels of IL-1beta, TNF-alpha, IL-2 and IFN-gamma and, especially their high ratios to IL-4 and IL-10 found in inflamed tissue biopsies, were closely associated with periodontal disease severity.