Development of Metronidazole-loaded In situ Thermosensitive Hydrogel for Periodontitis Treatment

Objectives: Periodontal treatment focuses on the thorough removal of specific periodontal pathogens, mainly anaerobic Gram-negative bacteria, by mechanical scaling and root planning. In case the periodontal abscess is detected after treatment, a high dose of antimicrobial agents is commonly applied via oral administration. However, this approach increases the risk of antibiotic resistance and systemic side effects and decreases efficacy. To overcome the aforementioned issues, this study focused on the development of thermosensitive hydrogel to deliver the antibiotic drug metronidazole (MTZ) directly and locally to the oral infection site. Materials and Methods: The thermosensitive hydrogels were prepared by blending 28% w/v Pluronic F127 with various concentrations of methylcellulose (MC) and silk fibroin (SF). The gel properties, such as sol-gel transition time, viscosity, and gel strength, were investigated. The drug dissolution profiles, together with their theoretical models and gel dissolution characteristics, were also determined. Results: All hydrogel formulations exhibited sol-gel transitions at 37°C within 1 min. An increase in MC content proportionally increased the viscosity but decreased the gel strength of the hydrogel. By contrast, the SF content did not significantly affect the viscosity but increased the gel strength of the hydrogel. The thermosensitive hydrogels also showed prolonged MTZ release characteristics for 10 days in phosphate-buffered saline (PBS) at pH 6.6, which followed the Higuchi diffusion model. Moreover, MTZ-thermosensitive hydrogel exhibited delayed dissolution in PBS at 37°C for more than 9 days. Conclusion: MTZ-thermosensitive hydrogels could be considered a prospective local oral drug delivery system to achieve efficient sustained release and improve the drug pharmacological properties in periodontitis treatment.

Unculturable and culturable periodontal-related bacteria are associated with periodontal inflammation during pregnancy and with preterm low birth weight delivery.

Recent studies revealed culturable periodontal keystone pathogens are associated with preterm low birth weight (PLBW). However, the oral microbiome is also comprised of hundreds of 'culture-difficult' or 'not-yet-culturable' bacterial species. To explore the potential role of unculturable and culturable periodontitis-related bacteria in preterm low birth weight (PLBW) delivery, we recruited 90 pregnant women in this prospective study. Periodontal parameters, including pocket probing depth, bleeding on probing, and clinical attachment level were recorded during the second trimester and following interviews on oral hygiene and lifestyle habits. Saliva and serum samples were also collected. After delivery, birth results were recorded. Real-time PCR analyses were performed to quantify the levels of periodontitis-related unculturable bacteria (Eubacterium saphenum, Fretibacterium sp. human oral taxon(HOT) 360, TM7 sp. HOT 356, and Rothia dentocariosa), and cultivable bacteria (Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Fusobacterium nucleatum and Prevotella intermedia) in saliva samples. In addition, ELISA analyses were used to determine the IgG titres against periodontal pathogens in serum samples. Subjects were categorized into a Healthy group (H, n = 20) and periodontitis/gingivitis group (PG, n = 70) according to their periodontal status. The brushing duration was significantly lower in the PG group compared to the H group. Twenty-two of 90 subjects delivered PLBW infants. There was no significant difference in periodontal parameters and serum IgG levels for periodontal pathogens between PLBW and healthy delivery (HD) groups. However, ordinal logistic regression analysis revealed that a higher abundance of Treponema denticola, Prevotella intermedia, Fretibacterium sp. HOT360 and lower levels of Rothia dentocariosa were significantly associated with the presence of periodontal disease during pregnancy. Moreover, the amount of Eubacterium saphenum in saliva and serum IgG against Aggregatibacter actinomycetemcomitans were negatively correlated with PLBW. Taken together, unculturable periodontitis-associated bacteria may play an important role both in the presence of periodontal inflammation during pregnancy and subsequent PLBW.

The periodontopathic bacteria in placenta, saliva and subgingival plaque of threatened preterm labor and preterm low birth weight cases: a longitudinal study in Japanese pregnant women.

OBJECTIVES: This study determined the quantity of periodontopathic bacteria in saliva, subgingival plaque, and placenta on the threatened preterm labor (TPL) and preterm low birth weight (PLBW) subjects in order to identify specific periodontal pathogens with high association to adverse pregnancy outcomes. METHODS: We used real-time PCR with TaqMan probe and ELISA to detect the amount of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Fusobacterium nucleatum, and Prevotella intermedia in subgingival plaque, saliva, and placenta tissue, in addition to serum IgG titers against these bacteria in 28 patients with TPL and 36 healthy pregnant women. RESULTS: Thirteen of 64 births delivered PLBW infants. All 6 periodontopathic bacteria were detected in the placenta samples. The amount of F. nucleatum and detection frequency of T. denticola in placental samples was significantly higher in the TPL group than in the healthy group. Meanwhile, the age, anti-P. gingival IgG in serum, amount of P. gingivalis and T. forsythia in plaque samples, detection frequency of P. intermedia in saliva, and percentage of pocket probing depth ≥ 5 mm were higher in TPL-PLBW births than those in TPL-Healthy delivery (HD) group and/or in H-HD group. Ordinal logistic regression analysis revealed that the presence of F. nucleatum in placental tissues was significantly associated with TPL, while the maternal age was significantly associated with PLBW in TPL. CONCLUSION: Our findings suggested all 6 bacteria may access the placenta. The increased presence of F. nucleatum in placenta might be related to TPL, while advanced maternal age might be associated with PLBW in TPL. CLINICAL RELEVANCE: Periodontal therapy should be applied to reduce the deep periodontal pocket sites and the colonization of periodontal pathogens in high-risk population.

Fretibacterium sp. human oral taxon 360 is a novel biomarker for periodontitis screening in the Japanese population.

BACKGROUND: Periodontitis is a common inflammatory disease, leading to bone destruction and tooth loss. Screening for periodontitis is important in preventing the progress of this disease. Various types of bacteria have been examined as potential screening targets, but only culturable pathogenic bacteria have been considered candidates. Recently, the various uncultivable bacteria have been identified in microbiome studies, but the value of these bacteria in periodontitis screening remains unknown. OBJECTIVES: The aim of this study was to evaluate the diagnostic use of uncultivable bacteria Fretibacterium sp. HOT 360 and TM7 sp. HOT 356 for periodontitis screening in the Japanese population. MATERIAL AND METHODS: Stimulated saliva samples were collected from 217 participants (periodontitis group, n = 157; healthy group, n = 60). The two uncultivable bacterial species selected were: Fretibacterium sp. human oral taxon 360 (Fretibacterium sp. HOT 360) and TM7 sp. human oral taxon 356 (TM7 sp. HOT 356). The levels of these two bacterial species were compared with those of Porphyromonas gingivalis (P. gingivalis), a keystone pathogen in periodontitis. These three species of bacteria were then quantified using qualitative real-time polymerase chain reaction (qPCR) with specific primers and Taqman probes. Statistical analysis was performed by SPSS 20.0 software. P value was statistically significant at .05. RESULTS: The populations of uncultivable bacterial species TM7 sp. HOT 356 and Fretibacterium sp. HOT 360 were significantly higher in periodontitis group than in healthy group. Only Fretibacterium sp. HOT 360 showed a significantly positive correlation with such periodontal parameters as probing pocket depth (PPD) and bleeding on probing (BOP). CONCLUSION: These findings indicate that uncultivable bacteria Fretibacterium sp. HOT 360 can be used as a saliva-based diagnostic bacterial biomarker for periodontitis screening.

Desensitizing Agent Reduces Dentin Hypersensitivity During Ultrasonic Scaling: A Pilot Study.

BACKGROUND: Dentin hypersensitivity can interfere with optimal periodontal care by dentists and patients. The pain associated with dentin hypersensitivity during ultrasonic scaling is intolerable for patient and interferes with the procedure, particularly during supportive periodontal therapy (SPT) for patients with gingival recession. AIM: This study proposed to evaluate the desensitizing effect of the oxalic acid agent on pain caused by dentin hypersensitivity during ultrasonic scaling. MATERIALS AND METHODS: This study involved 12 patients who were incorporated in SPT program and complained of dentin hypersensitivity during ultrasonic scaling. We examined the availability of the oxalic acid agent to compare the degree of pain during ultrasonic scaling with or without the application of the dentin hypersensitivity agent. Evaluation of effects on dentin hypersensitivity was determined by a questionnaire and visual analog scale (VAS) pain scores after ultrasonic scaling. The statistical analysis was performed using the paired Student t-test and Spearman rank correlation coefficient. RESULTS: The desensitizing agent reduced the mean VAS pain score from 69.33 ± 16.02 at baseline to 26.08 ± 27.99 after application. The questionnaire revealed that >80% patients were satisfied and requested the application of the desensitizing agent for future ultrasonic scaling sessions. CONCLUSION: This study shows that the application of the oxalic acid agent considerably reduces pain associated with dentin hypersensitivity experienced during ultrasonic scaling. This pain control treatment may improve patient participation and treatment efficiency.