Browsing by Subject "Dentin"

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    Hydrophobic and Antibiofilm Peptide-coated Dentin for Fortifying the Interfacial Integrity of Bonded Restorations
    (2018-12) Moussa, Dina
    Dental caries, i.e., tooth decay mediated by bacterial activity, is the most widespread chronic disease worldwide. With the evolution of bonded esthetic restorations, that look and function like natural teeth, it has become almost impossible for clinicians to proceed without them to restore carious teeth. Nonetheless, durability of esthetic restorations is notably compromised because of recurrent caries (RC), the principle cause of failure for esthetic restorations. RC mainly results from either waterborne (hydrolytic, acidic, enzymatic) and/or bacteria-mediated degradation of hydrophilic adhesives, which are required to interact with hydrated dentin at tooth-restoration interfaces. Therefore, transforming the hydrophilic interface into a water repellent one and/or incorporating a potent antibiofilm agent are potential strategies to resist RC. We have developed a novel application of amphipathic anti-microbial peptides (AAMPs) on dentin simultaneously used as a 2-tier protective system, hydrophobicity modulators and antibiofilm agents to resist RC around restoration margins. Cationic short AAMPs have been recently identified as potential alternatives to traditional antimicrobial agents and antibiotics due to their ability to specifically target the complex and heterogeneous organization of microbial communities where the latter are unlikely to develop resistance. We tested a series of AAMPs with strong amphipathic properties to assess their structure-function relationships. We found that AAMPs secondary structure (high portion of b-sheet), antimicrobial potency, and ability of the peptides to form hydrophobic coatings on dentin were inter-related. We also determined that AAMPs had preferential adsorption on the mineral phase of dentin, which suggested that peptides arrange their cationic and hydrophilic motifs in direct contact with the negatively-charged minerals in the hydrophilic dentin. We sought to study the impact of these AAMPs coatings on the dental plaque microbial community composition as well as their bacterial selectivity. We found that all D-amino acid AAMPs induced a marked shift in the plaque community by targeting 3 primary acidogenic colonizers. The consequent substantial antibiofilm potency of AAMPs-coated dentin was visualized using advanced bioimaging throughout 1 mm-deep dentin-composite interfaces. In conclusion, hydrophobic antibiofilm dentin is a versatile new approach to fortify the otherwise vulnerable adhesive-based interfaces of bonded restorations against the highly prevalent devastating RC.
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    Will Topical Application of Alendronate Disodium to Dental Roots Reduce Osteoclast Adherence and Resorption in Vitro?
    (2016-08) Finley, Rhett
    Introduction: The purposes of this study were: 1. To demonstrate the presence of fully differentiated, multinucleated human osteoclasts on bovine and human dentin and cementum in vitro. 2. To comparatively quantify osteoclast presence and distribution on tooth sections and adjacent lab wells following differentiation. 3. To comparatively quantify the amount of resorption that occurs when human root sections are subjected to a bisphosphonate antiresorptive treatment in comparison to no treatment. Materials and Methods: 30 sections of human tooth root and 48 sections of bovine tooth root were created using an IsoMet saw. The tooth sections from both groups were then divided into 2 equal groups of 15 and 24 sections respectively. One group received no treatment and the second group was soaked in 2mM Alendronate Disodium prior to transfer to culture. All sections were then plated in sterile culture wells with osteoclast precursor cells derived from whole human blood. The sections remained in culture until completion of osteoclastic differentiation, which took approximately 24 days. The supernatant was recovered from each well and used in an ELISA to determine the CTX-1 breakdown products from each section. The sections were fixed in paraformaldehyde and TRAP stained for visualization of osteoclasts. TRAP+ cell counts were performed on tooth sections and residual treatment wells. Student t-tests were used to determine differences between groups Results: Osteoclast attachment was observed on all human and bovine samples with the exception of one bacterially contaminated sample. The no treatment group had significantly more TRAP+ cells than the ALN group on both the human and bovine tooth sections. The no treatment group also had significantly more cells per residual well than the ALN group. No evidence of osteoclastic resorption could be demonstrated with the ELISA. Conclusions: Within the limitations of this study, it can be concluded that: 1. Fully differentiated, multinucleated osteoclasts can be successfully isolated from whole human blood and seeded onto human tooth sections in vitro. 2. Topical application of ALN disodium to extracted and sectioned tooth surfaces suppresses osteoclastic proliferation and differentiation in vitro. 3. Bovine teeth and human teeth allow for similar human osteoclast attachment and distribution in an in vitro model. 4. Mononuclear osteoclasts do not exhibit appreciable resorptive potential on sectioned surfaces in vitro.