An in vitro dynamic bioreactor model for evaluating antimicrobial effectiveness on periodontal polymicrobial biofilms: a proof-of-concept study.

BACKGROUND: The aim of this study was to investigate an in vitro dynamic bioreactor model by evaluating the antimicrobial effect of clinically relevant amoxicillin doses on polymicrobial microcosm biofilms derived from subgingival plaque. METHODS: Biofilms from pooled subgingival plaque were grown for 108  hours in control and experimental dynamic biofilm reactors. Amoxicillin was subsequently infused into the experimental reactor to simulate the pharmacokinetic profile of a standard 500 mg thrice-daily dosing regimen over 5 days and biofilms were assessed by live/dead staining, scanning electron microscopy, and quantitative polymerase chain reaction. RESULTS: Following establishment of the oral microcosm biofilms, confocal imaging analysis showed a significant increase in dead bacteria at 8 hours (p = 0.0095), 48 hours (p = 0.0070), 96 hours (p = 0.0140), and 120 hours (p < 0.0001) in the amoxicillin-treated biofilms compared to the control biofilms. Nevertheless, viable bacteria remained in the center of the biofilm at all timepoints. Significant reductions/elimination in Campylobacter rectus, Tannerella forsythia, Aggregatibacter actinomycetemcomitans, and Peptostreptococcus anaerobius was observed among the amoxicillin-treated biofilms at the 96 and 120 hour timepoints. CONCLUSION: A novel in vitro dynamic model of oral microcosm biofilms was effective in modeling the antimicrobial effect of a pharmacokinetically simulated clinically relevant dose of amoxicillin.

Evaluating models and assessment techniques for understanding oral biofilm complexity.

Oral biofilms are three-dimensional (3D) complex entities initiating dental diseases and have been evaluated extensively in the scientific literature using several biofilm models and assessment techniques. The list of biofilm models and assessment techniques may overwhelm a novice biofilm researcher. This narrative review aims to summarize the existing literature on biofilm models and assessment techniques, providing additional information on selecting an appropriate model and corresponding assessment techniques, which may be useful as a guide to the beginner biofilm investigator and as a refresher to experienced researchers. The review addresses previously established 2D models, outlining their advantages and limitations based on the growth environment, availability of nutrients, and the number of bacterial species, while also exploring novel 3D biofilm models. The growth of biofilms on clinically relevant 3D models, particularly melt electrowritten fibrous scaffolds, is discussed with a specific focus that has not been previously reported. Relevant studies on validated oral microcosm models that have recently gaining prominence are summarized. The review analyses the advantages and limitations of biofilm assessment methods, including colony forming unit culture, crystal violet, 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide inner salt assays, confocal microscopy, fluorescence in situ hybridization, scanning electron microscopy, quantitative polymerase chain reaction, and next-generation sequencing. The use of more complex models with advanced assessment methodologies, subject to the availability of equipment/facilities, may help in developing clinically relevant biofilms and answering appropriate research questions.

Fabrication and characterization of a 3D polymicrobial microcosm biofilm model using melt electrowritten scaffolds.

The majority of current biofilm models or substrates are two-dimensional (2D) and support biofilm growth in the horizontal plane only. Three-dimensional (3D) substrates may support both horizontal and vertical biofilm growth. This study compared biofilm growth quantity and quality between highly porous 3D micrometric fibrous scaffolds and 2D film substrates fabricated from medical grade polycaprolactone (mPCL). Melt electrowriting (MEW), a high-resolution additive manufacturing technology, was employed to design orderly aligned fine (~12 µm) fibre-based 3D scaffolds, while 2D films were fabricated by a casting method. The 3D scaffolds with a controlled pore size of 100 and 250 µm and thickness of ~0.8 mm and 2D films were incubated in pooled saliva collected from six volunteers for 1, 2, 4, 7 and 10 days at 37 °C to facilitate polymicrobial biofilm formation. Crystal violet assay demonstrated greater biofilm biomass in 3D MEW scaffolds than in 2D films. Biofilm thickness in 3D scaffolds was significantly higher compared to the biofilm thickness in 2D films. Both biovolume and substratum coverage of the biofilms was higher in the 3D scaffolds compared to 2D films. Polymeric bridges, pores, and channels characteristic of biofilms could be demonstrated by scanning electron microscopy. 16S rRNA sequencing demonstrated that the polymicrobial biofilms in the 3D scaffolds were able to retain 60-70 % of the original inoculum microbiome after 4 days. The MEW-fabricated 3D fibrous scaffold is a promising substrate for supporting multidirectional biofilm growth and modelling of a polymicrobial microcosm.

Awareness and Attitude among Physicians Regarding Bisphosphonaterelated Osteonecrosis of the Jaw (BRONJ): A Cross-sectional Study.

BACKGROUND: An invasive dental procedure is considered one of the risk factors for osteonecrosis of the jaw, especially among patients on bisphosphonates. This study aimed to determine the awareness and perceptions of medical practitioners regarding bisphosphonate-related osteonecrosis of the jaw (BRONJ), and their attitude towards dental referrals of such patients. METHODS: This cross-sectional questionnaire-based study was conducted among medical practitioners in and around Mysore city, Karnataka, India, who commonly prescribe bisphosphonates. The sample included orthopaedic doctors, physicians, endocrinologists, and oncologists, divided based on the duration of practice and speciality. Data on the type of practice, awareness of BRONJ, referral to a dentist before/during therapy, and patient education about adverse effects, were collected and analyzed. A p-value ≤0.05 was considered statistically significant. RESULTS: Among 58 practitioners, 84.5% (49) were aware of the association between bisphosphonates and BRONJ, while 56.9% (33/58) believed dental procedure to be a risk factor, and 55.2% (32/58) did not recommend screening of the oral cavity by a dentist before initiation of bisphosphonate therapy. A majority (65.5%) of them educated their patients about adverse effects. Mean knowledge scores varied with specialization (post-graduation vs. super specialization = 1.43 vs. 2; p = 0.01) but not with the duration of practice (<= 10 years vs. >10 years= 1.57 vs. 1.4; p= 0.24). CONCLUSION: The practitioners in our study were oblivious to dental procedures' role in the osteonecrosis of the jaw, highlighting the need for continuing education programs regarding BRONJ for medical and dental professionals. Clinicians updated regarding evidence-based practices and working cooperatively in teams may reduce the incidence of medication-related osteonecrosis of the jaw.

Quorum Sensing and Quorum Quenching with a Focus on Cariogenic and Periodontopathic Oral Biofilms.

Numerous in vitro studies highlight the role of quorum sensing in the pathogenicity and virulence of biofilms. This narrative review discusses general principles in quorum sensing, including Gram-positive and Gram-negative models and the influence of flow, before focusing on quorum sensing and quorum quenching in cariogenic and periodontopathic biofilms. In cariology, quorum sensing centres on the role of Streptococcus mutans, and to a lesser extent Candida albicans, while Fusobacterium nucleatum and the red complex pathogens form the basis of the majority of the quorum sensing research on periodontopathic biofilms. Recent research highlights developments in quorum quenching, also known as quorum sensing inhibition, as a potential antimicrobial tool to attenuate the pathogenicity of oral biofilms by the inhibition of bacterial signalling networks. Quorum quenchers may be synthetic or derived from plant or bacterial products, or human saliva. Furthermore, biofilm inhibition by coating quorum sensing inhibitors on dental implant surfaces provides another potential application of quorum quenching technologies in dentistry. While the body of predominantly in vitro research presented here is steadily growing, the clinical value of quorum sensing inhibitors against in vivo oral polymicrobial biofilms needs to be ascertained.

Salivary SARS-CoV-2 antibody detection using S1-RBD protein-immobilized 3D melt electrowritten poly(ε-caprolactone) scaffolds.

Sensitive detection of immunoglobulin antibodies against SARS-CoV-2 during the COVID-19 pandemic is critical to monitor the adaptive immune response after BNT162b2 mRNA vaccination. Currently employed binding antibody detection tests using 2D microplate-based enzyme-linked immunosorbent assays (ELISA) are limited by the degree of sensitivity. In this study, a 3D antibody test was developed by immobilizing the receptor-binding domain on Spike subunit 1 (S1-RBD) of SARS-CoV-2 onto engineered melt electrowritten (MEW) poly(ε-caprolactone) (PCL) scaffolds (pore: 500 µm, fiber diameter: 17 µm) using carbodiimide crosslinker chemistry. Protein immobilization was confirmed using X-ray photoelectron spectroscopy (XPS) by the presence of peaks corresponding with nitrogen. Self-developed indirect ELISA was performed to assess the functionality of the 3D platform in comparison with a standard 2D tissue culture plate (TCP) system, using whole unstimulated saliva samples from 14 non-vaccinated and 20 vaccinated participants (1- and 3- weeks post-dose 1; 3 days, 1 week and 3 weeks post-dose 2) without prior SARS-CoV-2 infection. The three-dimensional S1-RBD PCL scaffolds, while demonstrating a kinetic trend comparable to 2D TCP, exhibited significantly higher sensitivity and detection levels for all three immunoglobulins assayed (IgG, IgM, and IgA). These novel findings highlight the potential of MEW PCL constructs in the development of improved low-cost, point-of-care, and self-assessing diagnostic platforms for the detection and monitoring of SARS-CoV-2 antibodies.

Surface Modification of Pure Zinc by Acid Etching: Accelerating the Corrosion Rate and Enhancing Biocompatibility and Antibacterial Characteristics.

Zinc (Zn) has recently been identified as an auspicious biodegradable metal for medical implants and devices due to its tunable mechanical properties and good biocompatibility. However, the slow corrosion rate of Zn in a physiological environment does not meet the requirements for biodegradable implants, hindering its clinical translation. The present study aimed to accelerate the corrosion rate of pure Zn by utilizing acid etching to roughen the surface and increase the substrate surface area. The effects of acid etching on surface morphology, surface roughness, tensile properties, hardness, electrochemical corrosion and degradation behavior, cytocompatibility, direct cell attachment, and biofilm formation were investigated. Interestingly, acid-treated Zn showed an exceptionally high rate of corrosion (∼226-125 µm/year) compared to untreated Zn (∼62 µm/year), attributed to the increased surface roughness (Ra ∼ 1.12 µm) of acid-etched samples. Immersion tests in Hank's solution revealed that acid etching accelerated the degradation rate of Zn samples. In vitro, MC3T3-E1 cell lines in 50 and 25% conditioned media extracts of treated samples showed good cytocompatibility. Reduced bacterial adhesion, biofilm formation, and dispersion were observed for Staphylococci aureus biofilms cultured on acid-etched pure Zn substrates. These results suggest that the surface modification of biodegradable pure Zn metals by acid etching markedly increases the translation potential of zinc for various biomedical applications.

Secondhand smoke exposure from the indoor and outdoor shisha centers located at the perimeter of educational institutions in Malaysia: a cross-sectional study.

Shisha is a centuries-old traditional smoking habit rapidly gaining popularity among the students and young adults in Malaysia. The present study evaluated secondhand smoke exposure (SHS) and characteristics of 25 indoor and 25 outdoor shisha centers (SC) operating around the educational institutes such as universities in Petaling Jaya, Malaysia. We observed a significantly higher particulate matter (PM)2.5 concentration in indoor than outdoor SC (3595.28 µg/m3 and 65.12 µg/m3, p < 0.001, respectively). SCs are offering different flavors to attract clients and exposing students and young professionals to a significantly high concentration of SHS. Such exposures may pose a serious health risk. Therefore, policymakers need to strengthen tobacco guidelines and eliminate loopholes in the sale of shisha by enforcing comprehensive and strict smoke-free laws.

Influence of Grafting on Pocket Depth and Dentin Hypersensitivity Around Third Molar Extraction Sites: A Split-Mouth Randomized Controlled Trial.

This study evaluated the effect of alloplastic bone grafts in osseous defects following surgical removal of horizontally impacted third molars by comparing the periodontal measures distal to the second molar in grafted and nongrafted third molar extraction sites. Materials and Methods: A double-blind, randomized, controlled clinical trial was designed on subjects with bilateral horizontally impacted mandibular third molars. Grafting consisting of alloplasts at the third molar extraction sites was compared with nongrafted sites. This study assessed 54 randomized sites in 27 patients who were selected using a split-mouth design. The predictor variable included the change in pocket depth distal to the mandibular second molar and associated dentin hypersensitivity around the second molar, assessed preoperatively and at 3 and 6 months after third molar surgery. The data regarding pocket depth reduction was statistically analyzed using paired t-test. The data concerning reduction in dentin hypersensitivity was statistically analyzed using chi-square test. Results: Six months after third molar surgery, mean pocket depth distal to mandibular second molar decreased significantly at the grafted sites compared to the nongrafted sites. The reduction in dentin hypersensitivity of mandibular second molar was statistically significant for the grafted sites at 6 months, compared to the nongrafted sites.

Endogenous nitric oxide-generating surfaces via polydopamine-copper coatings for preventing biofilm dispersal and promoting microbial killing.

INTRODUCTION: Peri-implantitis is a bacterially induced inflammatory disease which affects the hard and soft tissues around a dental implant. Microbial biofilm formation is an important causative factor in peri-implantitis. The aim of this study is to develop an effective multifunctional surface coating for antimicrobial property and to counteract oral biofilm-associated infections via a single polydopamine copper coating (PDAM@Cu) on titanium implant surface to regulate endogenous nitric oxide (NO) generation. METHODS: PDAM@Cu coatings were made with different concentrations of CuCl2 on titanium surfaces with a simple dip coating technique. Coatings were characterised to evaluate Cu concentrations as well as NO release rates from the coatings. Further, salivary biofilms were made on the coatings using Brain Heart Infusion (BHI) media in an anaerobic chamber. Biofilms were prepared with three different mixtures, one of which was saliva only, the second had an addition of sheep's blood, and the third was prepared with NO donors S-nitrosoglutathione (GSNO) and L-glutathione (GSH) in the mixture of saliva and blood to evaluate the effects of endogenously produced NO on biofilms. The effectiveness of coated surfaces on biofilms were assessed using four different methods, namely, crystal violet assay, scanning electron microscopy imaging, 2,3-bis (2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide (XTT) metabolic assay, and live/dead staining. RESULTS: NO release rates could be controlled with different Cu concentration in PDAM@Cu coatings. NO generated from the PDAM@Cu coatings effectively induced dispersal of biofilms shown by the reduction in biofilm biomass as well as reduced biofilm attachment in samples prepared with blood and NO donors. Cu ions released from the PDAM@Cu coatings resulted in killing of the dispersed bacteria, which was evidenced by the live/dead cell staining and reduced metabolic activity noted from the XTT assay. In contrast, samples prepared with saliva showed no significant reduction in biofilms, indicating the important effect of endogenously generated NO on biofilm dispersal. CONCLUSION: In conclusion, PDAM@Cu coatings with NO generating surfaces have a dual anti-biofilm function, with a synergistic effect on biofilm dispersal from regulated NO generation and bactericidal effects from Cu ions from the coatings.

Case sharing - an approach for improving clinical experience to cases of advanced complexity among undergraduate dental students.

INTRODUCTION/PROBLEM: Clinical experience in cases of advanced complexity/rare cases is limited among undergraduate dental students. This commentary narrates a module termed "case sharing", wherein a small group of undergraduate dental students treat/assist, document and present advanced or rare cases to their entire cohort in eight weeks. APPROACH: Undergraduate students perform procedures of straightforward and moderate complexity, and later assisted the clinical specialists during procedures of advanced complexity. students document these cases with clinical photographs and case notes to make presentations that were uploaded in the faculty's online management system to be reviewed by the entire cohort. student groups presented their cases with their entire cohort. an independent assessor assessed the groups for their organization of the case, information collected on the topic, critical analysis of the case, defending the diagnosis and treatment plan, teamwork and presentation skills. EVALUATION: Students reported improvement in the depth of knowledge on particular diseases/procedures, a better understanding of holistic management of advanced cases, improved rapport, team spirit and communication among group members. they also reported difficulties in recruiting and completing the procedures within eight weeks. DISCUSSION: Apart from improving the clinical experience of undergraduate students, the module provides an opportunity for the development of teamwork, communication skills, and ethical presentations among students, which are invaluable to the faculty to meet its programme learning outcomes. case sharing provides a platform for holistic learning and serves as an alternative learning method aside from didactic lectures and routine clinical supervision.

Balancing assessment of depth and breadth in the dental curriculum: A bi-dimensional assessment strategy.

INTRODUCTION: Integrated curricula are being increasingly adopted in health professions, owing to their advantages including patient-centred training and development of critical thinking. Similarly, the majority of dental Universities have either moved away from discipline-specific towards integrated curricula or have incorporated elements of integration. Despite several advantages offered by the integrated curriculum, one disadvantage is failure to assess depth of knowledge. Assessing the depth of knowledge is a characteristic of discipline-specific curriculum. This commentary describes the inclusion of both discipline-based and integrated assessments at Faculty of Dentistry, SEGi University, Malaysia. MATERIAL AND METHODS: Module tests (discipline-based assessments) comprising of discipline specific questions are conducted at the end of every term, mimicking the traditional discipline-specific assessment. Questions in the module tests are intended to assess the depth of knowledge of students. Mid semester examinations are conducted at the end of the semester, mimicking the integrated assessment. Integrated questions are intended to test the breadth of knowledge of students. RESULTS: Lecturers and students felt introduction of module tests, helped them to prepare for topics in a phased manner and better answer questions posed by lecturers during case discussions and clinical presentations. The 'borderline distinction' students felt that studying for module tests provided them with the depth of knowledge essential to answer questions during viva voce. DISCUSSION: Including both the traditional and integrated methods of assessments would engage students in a learning experience developing their breadth and depth of knowledge. Further prospective research is essential to assess the impact of this assessment strategy.

Aggressive periodontitis with a history of orthodontic treatment.

This report presents a 29-year-old aggressive periodontitis patient from Morocco with a history of orthodontic treatment. Despite all the first molars showing advanced bone loss, the maxillary anterior teeth did not show any periodontal destruction. The scientific literature rarely reports cases of aggressive periodontitis without involving maxillary anterior teeth. The treatment provided includes extraction of hopeless tooth, removal of overhanging restoration, scaling, root debridement, and regenerative periodontal therapy. The discussion highlights the dilemma during diagnosis of the case as either "iatrogenic periodontitis due to orthodontic treatment" or "localized aggressive periodontitis." The age group of 15-35 years is the common age group for patients' seeking orthodontic treatment and the occurrence of aggressive periodontitis. Sound knowledge of periodontitis and identification of early signs of aggressive periodontitis through meticulous periodontal examination may help in earlier identification and minimalistic treatment. Education regarding periodontitis, especially aggressive periodontitis, is essential among orthodontists and general dentists. This case report aims to discuss the dilemma involved during diagnosis of localized aggressive periodontitis.

Knowledge about human papillomavirus (HPV) related oral cancers among oral health professionals in university setting-A cross sectional study.

INTRODUCTION: Scientific literature suggests that human papillomavirus (HPV) infection may be associated with oral squamous cell carcinoma (OSCC). However, knowledge regarding HPV-OSCC link among oral health professionals (OHP) has been insufficient. So, the aim of this study was to assess the knowledge about HPV associated OSCC among OHP working in dental faculties in Malaysia. METHODOLOGY: Ethical committee of the University approved this study. A validated, pre-tested questionnaire was sent electronically to 224 OHP. Questionnaire collected information regarding demography, knowledge about HPV-OSCC link, HPV vaccine, and willingness to educate patients about HPV OSCC link among the participants of this cross-sectional study. Data collected was analysed using "Stata/IC-13" and was summarised using descriptive statistics like frequency, percentage, mean and standard deviation. RESULTS: Out of 179 participants, around 39% of the participant's opined virus was not a causative factor for OSCC. Around, 44% replied posterior portion of the tongue/oro-pharynx was the commonest site for HPV related OSCC, whereas 29% replied that lateral border of the tongue was the common site for HPV related OSCC. Forty one percent educated patients regarding HPV infection being a causative factor for OSCC. HPV vaccine can prevent OSCC was stated by 70% OHP. Only 12% were aware of the availability of HPV vaccine in Malaysia. Majority (99%), agreed that there is a need to offer continuing education programmes to dentists highlighting advances and preventive strategies in the fight against OSCC. CONCLUSION: Substantial increase in awareness is required among OHP regarding HPV-OSCC link.

Disease Staging Index for Aggressive Periodontitis.

Major advances in the knowledge about the aetiopathogenesis of aggressive periodontitis (AgP) have been achieved. An ever increasing number of scientific articles related to AgP are published every year contributing significantly to the knowledge of this unique and complex disease. AgP has been classified into localised and generalised forms based on their extent and disease progression with distinct clinical and radiological features. A classification of AgP based on severity (mild, moderate and severe) exists; however, it is not easily applicable. Therefore, studies on AgP do not categorise the disease based on severity. A disease staging index for AgP is proposed based on clinical and radiological features, as well as risk factors. Based on the presence or absence of risk factors confirmed by longitudinal studies, cases of AgP can be divided into low risk, medium risk and high risk profiles for disease progression. Clinicians can devise a broad treatment plan for their AgP cases based on this staging. More frequent recall intervals are proposed for patients at medium and high risk for disease progression. Ten cases of AgP with 10-year follow-up were used to validate the staging index by retrospectively assigning prognosis and associating it with tooth loss. The use of this staging by researchers would increase external validity of research on AgP. Long-term analysis of AgP cases are needed to validate this staging index longitudinally.

Interleukin 1ß (+3954; -511) Genotype Polymorphism and its Association with Severe Chronic Generalized Periodontitis in the Malaysian Population.

INTRODUCTION: Single-nucleotide polymorphisms (SNPs) in interleukin 1ß (IL-1ß) gene have been known to be associated with increased susceptibility to chronic periodontitis among various ethnic populations. SNPs are more commonly observed at loci + 3954 and - 511. The aim of this study was to evaluate the role of IL-1ß gene polymorphism at loci +3954 and - 511, and its association with severe chronic generalized periodontitis among the ethnic Malay, Chinese, and Indians within the Malaysian population. MATERIALS AND METHODS: Saliva samples from 120 subjects (60 cases and 60 controls) in the age group of 25-50 years were collected for isolation of genetic material using Norgen technique. Clinical attachment loss of ≥5 mm was considered as severe chronic generalized periodontitis. SNP's at loci +3954 and - 511 were identified and analyzed using Kompetitive Allele Specific Polymerase Chain Reaction Genotyping System (KASP™). Differences in the allele/genotype frequencies were assessed by Chi-square test (P < 0.05). RESULTS: On the comparison between cases and controls of IL-1ß genotype polymorphism (+3954 and - 511), the difference in the genotype frequencies was statistically insignificant in all the three ethnicities. The genotype frequency in both groups in all three ethnicities of the Malaysian population was similar. CONCLUSION: IL-1ß genotype polymorphism at +3954 and - 511 was found to be not associated with severe chronic generalized periodontitis among the three ethnicities in Malaysia. Studies with larger sample size should be done to confirm the findings of this study.

Differential Diagnosis between Chronic versus Aggressive Periodontitis and Staging of Aggressive Periodontitis: A Cross-sectional Study.

BACKGROUND: Differentiating between chronic periodontitis (CP) and aggressive periodontitis (AgP) is challenging. The aim of this study was to assess the variations in diagnosis between CP versus AgP and the staging of AgP based on the disease-staging index for AgP among periodontists, specialists in oral medicine, and general dental practitioners (GDPs). MATERIALS AND METHODS: Fifteen cases diagnosed as either CP or AgP were included in a "case document" and sent electronically to 75 respondents. Case document included a detailed history with periodontal charting, clinical features, images, and radiographs for all the cases. Diagnosis and staging for the case (if diagnosed as AgP) were requested. A reordered case document (cases in a different sequence) was again sent to respondents after a gap of 1 month. STATISTICAL ANALYSIS: Descriptive statistics including frequency and percentage were calculated. Pearson's Chi-square test was used to analyze the data collected. RESULTS: For the "case document," 10.17% of the responses were different from those of the authors for diagnosis, whereas 4.48% of the responses were different from those of the authors for the staging of AgP. The agreement in the overall responses was in the range of 0.69-0.84, which was considered good. Comparison of the responses for diagnosis showed statistically significant (P = 0.009) difference between specialists in oral medicine and GDPs. CONCLUSIONS: Variations exist among respondents regarding the diagnosis of CP versus AgP. Staging of AgP based on the listed criteria showed low variations.