Faculty Bibliography

Dental caries are treated by the surgical removal of infected tissue where the biological mineral, hydroxyapatite, has been eroded. For early carious lesions, surgical methods have increasingly been replaced by minimally invasive dentistry protocols to arrest the lesion progression by controlling plaque formation and promoting dentin remineralization. Zinc phosphate mineral deposition in dentinal tubules was studied as a modality for the treatment of dental caries. Extracted permanent human molars, with and without carious lesions, were employed to study the coverage and depth of mineral deposition with in situ mixing of zinc and phosphate salt solutions. Milled hydroxyapatite was employed as a surrogate for dentin in the study of mineral formation in tubules. The mineral composition was identified by X-ray powder diffraction. Scanning electron microscopy and energy-dispersive X-ray spectroscopy revealed the deposition of zinc phosphate minerals that effectively occlude dentinal tubules by crystallization within dentinal tubules. Mineral deposition was similarly observed at the site of a carious lesion, which highlights the feasibility of zinc phosphate deposition for the treatment of dental caries.

BACKGROUND:While autografts to date remain the "gold standard" for bone void fillers, synthetic bone grafts have garnered attention due to their advantages such as ability to be tailored in terms of its physical and chemical properties. Bioactive glass (BG), an inorganic material, has the capacity to form a strong bond with bone by forming a bone-like apatite surface, enhancing osteogenesis. Coupled with three-dimensional printing it is possible to maximize bone regenerative properties of the BG. OBJECTIVE:The objective of this study was to synthesize and characterize 3D printed mesoporous bioactive glass (MBG), BG 45S5, and compare to β-Tricalcium phosphate (β-TCP) based scaffolds; test cell viability and osteogenic differentiation on human osteoprogenitor cells in vitro. METHODS:MBG, BG 45S5, and β-TCP were fabricated into colloidal gel suspensions, tested with a rheometer, and manufactured into scaffolds using a 3D direct-write micro-printer. The materials were characterized in terms of microstructure and composition with Thermogravimetric Analyzer/Differential Scanning Calorimeter (TGA/DSC), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Micro-Computed Tomography (μ-CT), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and Mattauch-Herzog-Inductively Coupled Plasma-Mass Spectrometry (MH-ICP-MS). RESULTS:Scaffolds were tested for cell proliferation and osteogenic differentiation using human osteoprogenitor cells. Osteogenic media was used for differentiation, and immunocytochemistry for osteogenic markers Runx-2, Collagen-I, and Osteocalcin. The cell viability results after 7 days of culture yielded significantly higher (p < 0.05) results in β-TCP scaffolds compared to BG 45S5 and MBG groups. CONCLUSION/CONCLUSIONS:All materials expressed osteogenic markers after 21 days of culture in expansion and osteogenic media.

Bone defects are associated with trauma, congenital disorders, non-unions, or infections following surgical procedures. Defects which are unable to heal spontaneously are categorized as "critical sized" and are commonly treated using bone grafts in an effort to facilitate bone regeneration and stabilization. Grafting materials can be either natural or synthetic, each having their respective advantages and disadvantages. Synthetic bone grafts are favored due to their ability to be tailored to exhibit desired properties and geometric configurations. β-tricalcium phosphate (β-TCP) is a synthetic grafting material that has been widely utilized for regenerative purposes due to its favorable osteoconductive properties. In combination with 3D printing, grafting materials can be further customized with respect to their macro and micro features. One way to customize devices is by using 3D printing and varying the surface area, by varying the internal component measurements. The objective of this study was to compare the effect of porosity and surface area of 3D printed β-TCP scaffolds with different strut diameters and the effect on cell proliferation in vitro. ß-TCP scaffolds were printed using a custom-built 3D direct-write micro printer with syringes equipped with different extrusion tip diameters (fdiameter: 200 µm, 250 µm and 330 µm). After sintering and post processing, scaffolds were subjected to micro-computed tomography (µCT) and a Scanning Electron Microscope (SEM) to evaluate surface area and porosity, respectively. Compressive strength was assessed using a universal testing machine. Cell proliferation was assessed through cellular viability, using human osteoprogenitor cells. The surface area of the scaffolds was found to increase with smaller strut diameters. Statistically significant differences (p<0.05) were detected for cellular proliferation, between the smallest extrusion diameter, 200 μm, and the largest diameter, 330 μm, after 48-, 72-, and 168-hours. No statistical significances were detected (p>0.05) with regards to the mechanical properties between groups. This study demonstrated that a smaller diameter rod yielded a higher surface area resulting in increased levels of cellular proliferation. Therefore, tailoring rod dimensions has the capacity to enhance cellular adhesion and ultimately, proliferation.

INTRODUCTION/BACKGROUND:This article reports, after at least 10 years of follow-up, the comparative data of marginal bone loss (MBL) and periimplant soft tissue parameters, around implant with and without laser-microtextured (L) collar surface, previously reported at 3 years of follow-up. MATERIALS AND METHODS/METHODS:Twenty implants with L collar surface (test) were placed adjacent to 20 control implants with machined (M) collar surface in 15 partially edentulous patients, who were followed up for at least 10 years as part of a prospective longitudinal study. The plaque score, bleeding on probing (BoP) score, and probing depth (PD) were recorded at baseline and at each year follow-up examination. Mucosal recession (MR), and radiographic MBL were assessed at baseline and after at least 10 years. RESULTS:Four patients were lost during follow-up, so the number of implants that have been followed for at least 10 years was 32 (16 tests and 16 controls). At the end of the follow-up period, no significant differences were found between the study groups regarding the presence of plaque and BoP (P > 0.05). A statistically significant difference between test and control implant was found for mean PD (2.3 ± 0.7 mm vs 3.8 ± 0.8), MBL (1.23 ± 0.21 mm vs 2.8 ± 0.9 mm), and mean MR (1.08 ± 0.4 mm vs 2.46 ± 0.3 mm). CONCLUSION/CONCLUSIONS:Results suggest that after at least 10 years of function, implants with laser-microtexturing (L) collar surface, compared with implants with machined surface, lead to lower MBL and PD.

Purpose/UNASSIGNED:thin films with photocatalytical activity with previously confirmed antibacterial properties. Materials and methods/UNASSIGNED:thin films fabricated by anodization and annealing of cpTi were used to culture MC3T3-E1 cells to evaluate the initial cellular adhesion morphology and ALP activity in vitro. Results/UNASSIGNED:thin films exhibited similar ALP levels after cell culture day 9. Conclusion/UNASSIGNED:Anodizing and annealing processes fabricate multifunctional surfaces on cpTi with improved osteogenic properties for implants.

The treatment of peri-implant disease is one of the most controversial topics in implant dentistry. The multifactorial etiology and the myriad proposed techniques for managing the problem make successful decontamination of an implant surface affected by peri-implantitis one of the more unpredictable challenges dental practitioners have to face. This article presents the first known published case report demonstrating human histologic evidence of reosseointegration using a plastic curette for mechanical debridement and dilute sodium hypochlorite, hydrogen peroxide, and sterile saline for chemical detoxification. Guided bone regeneration in the infrabony component of the peri-implantitis lesion was accomplished using calcium sulfate and bovine bone as grafting materials and a porcine collagen barrier for connective tissue and epithelial exclusion.

Bone defects resulting from trauma or infection need timely and effective treatments to restore damaged bone. Using specialized three-dimensional (3D) printing technology we have created custom 3D scaffolds of hydroxyapatite (HA)/beta-tri-calcium phosphate (beta-TCP) to promote bone repair. To further enhance bone regeneration we have coated the scaffolds with dipyridamole, an agent that increases local adenosine levels by blocking cellular uptake of adenosine. Nearly 15% HA:85% beta-TCP scaffolds were designed using Robocad software, fabricated using a 3D Robocasting system, and sintered at 1100 degrees C for 4 h. Scaffolds were coated with BMP-2 (200 ng mL-1 ), dypiridamole 100 microM or saline and implanted in C57B6 and adenosine A2A receptor knockout (A2AKO) mice with 3 mm cranial critical bone defects for 2-8 weeks. Dipyridamole release from scaffold was assayed spectrophotometrically. MicroCT and histological analysis were performed. Micro-computed tomography (microCT) showed significant bone formation and remodeling in HA/beta-TCP-dipyridamole and HA/beta-TCP-BMP-2 scaffolds when compared to scaffolds immersed in vehicle at 2, 4, and 8 weeks (n = 5 per group; p