Newly discovered clouting interplay between matrix metalloproteinases structures and novel quaternary Ammonium K21: computational and in-vivo testing.

AIMS AND OBJECTIVES: To analyze anti-MMP mode of action of Quaternary Ammonium Silane (QAS, codenamed as k21) by binding onto specific MMP site using computational molecular simulation and Anti-Sortase A (SrtA) mode of action by binding onto specific site using computational molecular simulation. MATERIALS AND METHODS: In silico Molecular Dynamics (MD) was used to determine the interactions of K21 inside the pocket of the targeted protein (crystal structure of fibroblast collagenase-1 complexed to a diphenyl-ether sulphone based hydroxamic acid; PDB ID: 966C; Crystal structure of MMP-2 active site mutant in complex with APP-derived decapeptide inhibitor. MD simulations were accomplished with the Desmond package in Schrödinger Drug Discovery Suite. Blood samples (~ 0.5 mL) collected into K2EDTA were immediately transferred for further processing using the Litron MicroFlow® PLUS micronucleus analysis kit for mouse blood according to the manufacturer's instructions. Bacterial Reverse Mutation Test of K21 Molecule was performed to evaluate K21 and any possible metabolites for their potential to induce point mutations in amino acid-requiring strains of Escherichia coli (E. coli) (WP2 uvrA (tryptophan-deficient)). RESULTS: Molecular Simulation depicted that K21 has a specific pocket binding on various MMPs and SrtA surfaces producing a classical clouting effect. K21 did not induce micronuclei, which are the result of chromosomal damage or damage to the mitotic apparatus, in the peripheral blood reticulocytes of male and female CD-1 mice when administered by oral gavage up to the maximum recommended dose of 2000 mg/kg. The test item, K21, was not mutagenic to Salmonella typhimurium (S. typhimurium) strains TA98, TA100, TA1535 and TA1537 and E. coli strain WP2 uvrA in the absence and presence of metabolic activation when tested up to the limit of cytotoxicity or solubility under the conditions of the test. CONCLUSION: K21 could serve as a potent protease inhibitor maintaining the physical and biochemical properties of dental structures.

Cathepsin-K inhibition enhances anti-cancerous activity within oral squamous cell carcinoma cells: Uncloaking the potency of new K21 formulation.

BACKGROUND: The ability of cancer cells to be invasive and metastasize depend on several factors, of which the action of protease activity takes center stage in disease progression. PURPOSE/OBJECTIVE: To analyze function of new K21 molecule in the invasive process of oral squamous cell carcinoma (OSCC) cell line. MATERIALS & METHODS: The Fusobacterium (ATCC 23726) streaks were made, and pellets were resuspended in Cal27 (ATCC CRL-2095) OSCC cell line spheroid cell microplate. Cells were seeded and Lysotracker staining performed for CathepsinK red channel. Cell and morphology were evaluated using Transmission Electron microscopy. Thiobarbituric acid assay was performed. OSCC was analyzed for Mic60. Raman spectra were collected from the cancer cell line. L929 dermal fibroblast cells were used for Scratch Assay. ELISA muti arrays were used for cytokines and matrix molecules. Internalization ability of fibroblast cells were also analyzed. Structure of K21 as a surfactant molecule with best docked poses were presented. RESULTS: Decrease in lysosomal staining was observed after 15 and 30 min of 0.1% treatment. Tumor clusters were associated with cell membrane destruction in K21 primed cells. There was functional silencing of Mic60 via K21, especially with 1% concentration with reduced cell migration and invasiveness. Raman intensity differences were seen at 700 cm-1, 1200 cm-1 and 1600 cm-1 regions. EVs were detected within presence of fibroblast cells amongst K21 groups. Wound area and wound closure showed the progress of wound healing. CONCLUSION: Over expression of CatK can be reduced by a newly developed targeted K21 based drug delivery system leading to reduced migration and adhesion of oral squamous cell carcinoma cells. The K21 drug formulation can have great potential for cancer therapies due to targeting and cytotoxicity effects.

Recent Update on Applications of Quaternary Ammonium Silane as an Antibacterial Biomaterial: A Novel Drug Delivery Approach in Dentistry.

Quaternary ammonium silane [(QAS), codename - k21] is a novel biomaterial developed by sol-gel process having broad spectrum antimicrobial activities with low cytotoxicity. It has been used in various concentrations with maximum antimicrobial efficacy and biocompatibility. The antimicrobial mechanism is displayed via contact killing, causing conformational changes within the bacterial cell membrane, inhibiting Sortase-A enzyme, and causing cell disturbances due to osmotic changes. The compound can attach to S1' pockets on matrix metalloproteinases (MMPs), leading to massive MMP enzyme inhibition, making it one of the most potent protease inhibitors. Quaternary ammonium silane has been synthesized and used in dentistry to eliminate the biofilm from dental tissues. QAS has been tested for its antibacterial activity as a cavity disinfectant, endodontic irrigant, restorative and root canal medication, and a nanocarrier for drug delivery approaches. The review is first of its kind that aims to discuss applications of QAS as a novel antibacterial biomaterial for dental applications along with discussions on its cytotoxic effects and future prospects in dentistry.

Current and future trends in the teaching of removable partial dentures in dental schools in Malaysia: A cross sectional study.

AIMS: To investigate, using a validated questionnaire, the teaching of removable partial dentures (RPDs) in dental schools of Malaysia. MATERIALS AND METHODS: A validated questionnaire to investigating trends in the teaching of RPDs in dental schools in Oceania was emailed (in English version form) to Heads of Restorative/Prosthodontics/course coordinators in the 13 dental schools in Malaysia. Follow-up reminders were sent and participants were given six weeks to complete and return the questionnaire. Data was entered into an Excel spreadsheet and results compiled and analyzed. RESULTS: Completed questionnaires were received from 13 dental school - a 100% response rate. All schools (n = 13) provided a preclinical technical course in RPD design. In most schools (n = 9, 69.2%), course work was supervised by senior lecturers while rest of the institutions made use of associate professor/professors. There were significant differences (p<0.05) between dental schools in terms of the contact hours dedicated to preclinical teaching. Students received an average of 62 h of instruction. Didactic instruction was the primary focus with practical (78 h) and didactic teaching (32 h). All dental schools (n = 13) provided practical surveyor design teaching (8 h). The staff student ratio for formal lectures (1:61), tutorials (1:29) and lab demonstrations (1:12) were recorded. Majority of the schools (n = 11, 84.6%) employed paired teaching in clinical sessions. All schools (n = 13, 100%) emphasized on increased teaching of RPD design and prescription writing in future clinical RPD courses. CONCLUSION: Teaching of RPDs in Malaysia may be considered sufficient and comparable to the teaching in other parts of the world. CLINICAL SIGNIFICANCE: Whilst the teaching of partial dentures at Dental Schools in Malaysia provides the core competencies involved in partial denture design and construction based on sound fundamental, scientific principles they should address the challenges of teaching partial dentures and other areas of dental education including improving working conditions for dental professionals.

Characterization of multiscale interactions between high intensity focused ultrasound (HIFU) and tooth dentin: the effect on matrix-metalloproteinases, bacterial biofilms and biological properties.

The aim of this study was to characterize multiscale interactions between high intensity focused ultrasound (HIFU) and dentin collagen and associated matrix-metalloproteinases, in addition to the analysis of the effect of HIFU on bacterial biofilms and biological properties. Dentin specimens were subjected to 5, 10 or 20 s HIFU. XPS spectra were acquired and TEM was performed on dentin slabs. Collagen orientation was performed using Raman spectroscopy. Calcium measurements in human dental pulpal cells (hDPCs) were carried out after 7 and 14 days. For macrophages, CD36+ and CD163+ were analysed. Biofilms were analyzed using CLSM. Tandem mass spectroscopy was performed for the detection of hydroxyproline sequences along with human MMP-2 quantification. Phosphorus, calcium, and nitrogen were detected in HIFU specimens. TEM images demonstrated the collagen network appearing to be fused together in the HIFU 10 and 20 s specimens. The band associated with 960 cm-1 corresponds to the stretching ν1 PO43-. The control specimens showed intensive calcium staining followed by HIFU 20 s > HIFU 10 s > HIFU 5 s specimens. Macrophages in the HIFU specimens co-expressed CD80+ and CD163+ cells. CLSM images showed the HIFU treatment inhibiting bacterial growth. SiteScore propensity determined the effect of HIFU on the binding site with a higher DScore representing better site exposure on MMPs. Multiscale mapping of dentin collagen after HIFU treatment showed no deleterious alterations on the organic structure of dentin.

New antimicrobial and collagen crosslinking formulated dentin adhesive with improved bond durability.

OBJECTIVE: Here we describe a novel formulation, based on quaternary ammonium (QA) and riboflavin (RF), which combines antimicrobial activities and protease inhibitory properties with collagen crosslinking without interference to bonding capabilities, was investigated. METHODS: Experimental adhesives modified with different fractions of dioctadecyldimethyl ammonium bromide quaternary ammonium and riboflavin (QARF) were formulated. Dentine specimens were bonded to resincomposites with control or the experimental adhesives to be evaluated for bond strength, interfacial morphology, micro-Raman analysis, nano-CT and nano-leakage expression. In addition, the antibacterial and biocompatibilities of the experimental adhesives were investigated. The endogenous proteases activities and their molecular binding-sites were studied. RESULTS: Modifying the experimental adhesives with QARF did not adversely affect micro-tensile bond strength or the degree of conversion along with the demonstration of anti-proteases and antibacterial abilities with acceptable biocompatibilities. In general, all experimental adhesives demonstrated favourable bond strength with increased and improved values in 1% QARF adhesive at 24 h (39.2 ± 3.0 MPa) and following thermocycling (34.8 ± 4.3 MPa). SIGNIFICANCE: It is possible to conclude that the use of QARF with defined concentration can maintain bond strength values when an appropriate protocol is used and have contributed in ensuring a significant decrease in microbial growth of biofilms. Incorporation of 1% QARF in the experimental adhesive lead to simultaneous antimicrobial and anti-proteolytic effects with low cytotoxic effects, acceptable bond strength and interfacial morphology.

Viscosity effects of polyvinyl siloxane impression materials on the accuracy of the stone die produced.

BACKGROUND: The purpose of the present study was to investigate the effect of different viscosities of polyvinyl siloxane (PVS) impression materials on the accuracy of the stone die produced. METHODS: A three-unit bridge master model was fabricated using cold-cure acrylic resin. Four combinations of different viscosities of PVS impression materials - regular body (monophase) alone, light body with regular body, light body with heavy body, and light body with putty - were used to make an impression of the master model. Ten impressions from each group were taken and Type IV gypsum stone was used to generate the dies. The dies were measured at the inter-abutment distance, occlusogingival length, and shoulder width with a measuring microscope and were compared with the master model using one-way analysis of variance and Tukey (honest significant difference) test. RESULTS: Differences were found for inter-abutment distance between the master model and the light body with regular body and light body with putty dies (both P < 0.02). A difference was found for shoulder width between the master model and the regular body alone die (P = 0.01). No differences were found for occlusogingival distance (all P > 0.08). CONCLUSION: Results suggested inter-abutment distance was most accurate when using a PVS light body combination. Occlusogingival length was accurate using any of the studied PVS combinations, and shoulder width was more accurate when using the regular body PVS. RELEVANCE FOR PATIENTS: These results should be considered when choosing the viscosity of the PVS to use for producing impressions of high accuracy and fabricating a well-fitting fixed prosthesis.