• Biocompatibility and mechanical/physical properties of 3D printed, milled, and conventionally processed denture base materials

      Ulmer, Mallory; Biomedical Sciences (Augusta University, 2019-12)
      According to the American College of Prosthodontists, over 36 million people in the USA are edentulous with a 2:1 predilection for geriatric patients1. Each year, an estimated 15% of edentulous Americans will seek denture treatment1. Conventional dentures require multiple visits and lab processing time. 3D printing technology offers the potential to reduce the number of appointments and speed up the time until patient rehabilitation. However, the newly FDA-certified 3D printer denture resins, featuring secretive and proprietary formulae, lack studies concerning their biocompatibility/safety and mechanical strength. This study aims to investigate the biocompatibility and physical properties of one such 3D printer resin, NextDent® Base (Vertex, Soesterberg, The Netherlands), and compare it to pre-existing conventional polymethyl methacrylate (PMMA) denture base (Lucitone 199, Dentsply Sirona, York, Pennsylvania) and milled PMMA denture base (IvoBase CAD®, Ivoclar Vivadent AG, Schaan, Liechtenstein). The cytotoxicity was examined using of 12 discs: conventional PMMA, milled PMMA, as-printed 3D printer resin, post-cured 3D printer resin, and Teflon controls. An MTT assay using human periodontal ligament (900L) cells was employed, and specimens were aged for 1, 3, 7, 10, and 14 days. After day 7, there were no statistically significant differences among the groups, excluding the Teflon control, which showed significantly less cell viability on day 14. Bars of conventional PMMA, milled PMMA, as-printed 3D printer resin, and post-cured 3D printer resin were subjected to a 3-point bend test to examine flexural strength and moduli differences. The mean flexural strength was 63.8 ± 3.06, 82.6 ± 1.9, 5.1 ± 0.4, and 22.1 ± 6.4 MPa, respectively, while the flexural moduli were 1757.3 ± 109.5, 2226.7 ± 76.3, 110.3 ± 20.3, and 537.0 ± 210.6 MPa, respectively. The flexural strength and modulus were significantly different among all groups. Weibull analyses for conventional PMMA, milled PMMA, as-printed 3D printer resin, and post-cured 3D printer resin revealed a Weibull modulus of 23.5, 42.8, 16.6, and 3.7, respectively, and a characteristic strength of 65.2, 83.5, 5.3, and 24.5 MPa, respectively. The characteristic strength was significantly different among all groups as well. The Weibull modulus was significantly different between all groups, except for conventional vs. as-printed, which were not significantly different. In summary, milled PMMA featured significantly greater mechanical properties. Both 3D printed groups proved to be very weak, with the as-printed group being the weakest of all. The differences between the as-printed and post-cured groups highlight the importance of properly post-curing the resin. While the biocompatibility results showed promise, the mechanical testing results were disappointing. Unfortunately, the findings suggest that 3D-printed denture base resin is not yet ready for clinical use.
    • Case Selection Criteria for use with Resin-Infiltrative Treatment of Enamel Decalcification

      Raley, N; Clayton, Ashley; Fortson, WM; Deleon, E; Rueggeberg, FA; Department of Orthodontics, Department of Restorative Sciences (Augusta University, 2019)
      Although one of the primary aims for many orthodontic patients is to achieve improvement in their dental esthetic condition, a high percentage of these patients develop unesthetic, white spot lesions (WSL) during the course of treatment. These lesions develop due to enamel decalcification resulting from bacterial plaque accumulation around difficult to clean brackets and overlying wires and ligation devices. Acids produced locally in this retained plaque will decalcify enamel along the peripheral border of the bonded bracket. Quite often, despite repeated admonishment by the clinician to the patient to take extra care in cleansing these susceptible locations, patients return with large plaque deposits around the brackets, and evidence of the early stages of enamel decalcification: the so-called “white spot lesion” (WSL). The problem becomes obvious at the time of bracket removal, when, although the teeth may now be arranged in near-to-perfect alignment and occlusion, large, white areas of enamel decalcification are prominently displayed, denoting the exact location of where the bonded bracket used to be.
    • Caspase-14: A novel caspase in the retina with a potential role in diabetic retinopathy

      Al-Shabrawey, Mohamed; Ahmad, Saif; Megyerdi, Sylvia; Othman, Amira; Baban, Babak; Palenski, Tammy L.; Shin, Eui Seok; Gurel, Zafer; Hsu, Stephen; Sheibani, Nader; et al. (2012-07-14)
      Purpose: The purpose of this study was to evaluate caspase-14 expression in the retina under normal and diabetic conditions, and to determine whether caspase-14 contributes to retinal microvascular cell death under high glucose conditions.
    • Cellular and Immunocytochemical Response to Mandibular Distraction Using an Implanted Lengthening Device

      Elbokle, Nadar N; Department of Oral Biology (2004)
      Distraction osteogenesis (DO) is a biologic process that generates new bone between surfaces of bone segments, which are gradually separated by traction forces. It is a uniquely effective method with multiple applications in the craniofacial region. This concept has been the basis of all bone-lengthening operations; it involved an osteotomy of the shortened bone and an external/internal fixator device, which slowly elongates the bone to its new dimension while a bony callus is being formed at the side to distraction. The biology of DO is similar to callus fracture healing. The bony regenerate passes through the same phases: formation of a collagen fibril template, mineralization, bony union and finally remodeling. The mechanisms by which the mechanical stresses applied to the bone tissue cause the cells to proliferate and form new bone are not well understood. More studies are needed to understand the cellular events underlying DO and the effects of the strains applied during DO on cellular proliferation and mineral apposition.
    • Changes in the RANK/RANKL/OPG Signaling System as a Mechanism of Zoledronate-Induced Osteonecrosis of the Jaw

      Lane, Jonathan; Department of Oral Biology (3/22/2016)
      Bisphosphonates (BPs) are widely used for the treatment of osteoporosis, hypercalcemia of malignancy, skeletal-related events associated with bone metastases, and for managing lytic lesions of multiple myeloma. A serious risk associated with the use of BPs is the development of Bisphosphonate Related Osteonecrosis of the Jaw (BRONJ), a painful and inflamed area of exposed bone in the oral cavity that fails to heal after 6-8 weeks. The cause of BRONJ is unknown, but it is believed to be due primarily to a longterm suppression of bone remodeling, caused by BP’s potent inhibition of osteoclastic activity. At the cellular level, it is generally accepted that bisphosphonates are taken in by osteoclasts at sites of relatively greater bone remodeling, owing to the strong affinity of bisphosphonates for the mineralized matrix and the increased activity of osteoclasts at active sites of resorption. The accumulation of intracellular bisphosphonates ultimately leads to osteoclast dysfunction or apoptosis through the formation of nonhydrolyzable ATP-analogues, or due to inhibition of the mevalonate pathway responsible for synthesis of sterols and lipids necessary for proper cellular membrane structure. However, the refined details of the pathophysiology of BRONJ remain elusive. The RANK/RANKL/OPG system is a well-known signaling pathway for the recruitment and differentiation of osteoclasts. RANK is a surface-bound receptor on osteoclasts, and requires binding of its ligand, RANKL, for cell activation and ultimately resorption of bone. On the other hand, OPG is a soluble decoy receptor for RANKL. Therefore, osteoclastic activity is effectively regulated by the ratio of RANKL to OPG. For years, it has been generally accepted that osteoblasts are the primary source of both RANKL and OPG. However, it is now recognized that the master orchestrator of bone activity, the osteocyte, contributes to the pathway. Furthermore, it has been shown that in localized tissue damage or hypoxia, such as in a dental extraction, immediately adjacent surviving nonapoptotic osteocytes upregulate RANKL and downregulate OPG. It is unknown to what extent BPs may alter the normal osteocyte response to injury and hypoxia or, ultimately, the dynamics of the RANK/RANKL/OPG system. Furthermore, the extent to which this could contribute to the development of BRONJ is unexplored.There is a paucity of studies concerning how the fundamental system responsible for bone remodeling, RANK/RANKL/OPG, is effected by BPs. It may be that changes in this system, especially in signals derived from the osteocyte, contribute to the pathophysiology of BRONJ.
    • Characteristics of inflammation common to both diabetes and periodontitis: are predictive diagnosis and targeted preventive measures possible?

      Hanes, Philip J.; Krishna, Ranjitha; Department of Periodontics (2010-04-3)
      Keywords: Periodontitis
    • Clinical Guide for Intraosseous Pathology

      Malik, M; Kalathingal, S; Cullum, A; Buchanan, A; Abdelsayed, A; Kurago, Z; Department of Oral Biology & Diagnostic Sciences, Center for Instructional Innovation (Augusta University, 2019)
      To provide a reference database for dental students to describe and analyze intra osseous pathology that aid to develop a list of differential diagnoses for various diseases affecting the maxillofacial region on patients treated in student clinics. The online database will serve as a resource for descriptive terminology and samples to demonstrate the origin of the lesion, radiographic appearance, borders, contents, effects on adjacent structures, etc. which are the fundamental elements that guide a clinician in developing an impression and formulate the differential diagnosis. Histopathologic evaluation that provides the final diagnosis of each disease process will also be included to demonstrate that radiographic presentation of various disease categories may be similar, however, clinical management is ultimately decided by the tissue sample from the biopsy specimen. The interactive database will have various features that enable the user to access a comprehensive glossary list, word- defined searches, a brief overview of the most common diseases affecting dento-alveolar regions and learn about the management strategies.
    • Conservative Porcelain Veneer: Step by step protocol for ideal preparation

      Wooten, Rebekah; Coleman, J; Pruett, M; Romeo, M (Augusta University, 2019)
      Since the 1930s laminate veneers have been commonly used to improve appearance of teeth, but they did not become popular until enamel etching and porcelain surface treatments made them more clinically predictable in the 1980s.1 Over the years, they have been indicated to modify the color, shape, length and alignment of teeth to improve their esthetic appearance. Contraindications include severely discolored teeth and lack of enamel remaining to support the restoration.3 Treatment planning is the first step to ideal veneer preparation, which involves determining the incisal edge position, shape and proportions of the teeth being restored. This information is obtained form the diagnostic wax-up and subsequent esthetic mock-up. Veneer preparations often follow one of two common reduction patterns: conservative or standard. The difference between the two being the amount of tooth structure removed. The conservative approach involves reduction of 0.3 mm gingival third, 0.5 mm middle third, and 0.7 mm incisal third; or no reduction may be required. The standard preparation typically follows a reduction pattern of 0.8 mm gingival, 1.0 mm middle, and 1.2 mm incisal. Incisal reduction can be characteristic of either technique to allow room for the addition of incisal effects such as halo and translucency. In order to ensure porcelain veneers have the maximum lifetime expectancy, it is imperative to have preparations entirely in enamel. Bonding porcelain veneers to enamel increases their fracture strength. 2 Based on the best available evidence the ten year survival rate for porcelain veneers is at around 95% if bonded to enamel.1 Maxillary midline diastemas (MMD) are present in 28% of the population, and 87.5% of females with a midline diastema are dissatisfied and seek treatment.3 This clinical report focuses on the clinical management of a maxillary midline diastema (MMD) with porcelain veneers through a conservative preparation and incisal reduction.
    • Correlation of Deph of Solvent Resistance with Monomer Conversion

      Keller, Elizabeth; Rueggeberg, Frederick A.; Department of Restorative Sciences (2017-03)
      In the mouth, inadequately cured dental restorative materials may lead to detrimental consequences in their longevity. As light travels through these photo-curable restorative composites, there is an exponential decrease in light penetration with depth, and therefore the extent of local polymerization is compromised. This phenomenon is termed the “Depth of Cure” issue, which restricts the thickness if increment that each restorative material can be placed and polymerized. The purpose of this research is to develop an easily performed test that provides a correlational value between visually identifiable transition zones within acetone-sonicated, sectioned, cured composite specimens and the extent to which a composite has reached maximal monomer conversion values, to ultimately determine adequacy of polymerization at the depth of cure for certain restorative materials. This test method, proven to be independent of composite type, will be submitted to the working group associated with the revision of the International Organization for Standards Organization 4049 standard, for consideration of further testing and perhaps replacement of the current method. This research provides a fulfillment of the requests from well-respected dental clinicians to provide a clinically relevant and meaningful depth of cure test.
    • Dentin Sialophosphoprotein (DSPP) Gene-Silencing Inhibits Key Tumorigenic Activities in Human Oral Cancer Cell Line, OSC2

      Joshi, Rajeshree; Tawfik, Amany; Edeh, Nneka; McCloud, Veronica; Looney, Stephen W.; Lewis, Jill; Hsu, Stephen; Ogbureke, Kalu U.E.; Department of Oral Biology; Department of Pathology; et al. (2010-11-12)
      Background: We determined recently that dentin sialophosphoprotein (DSPP), a member of the SIBLING (Small integrin-binding ligand N-linked glycoproteins) family of phosphoglycoproteins, is highly upregulated in human oral squamous cell carcinomas (OSCCs) where upregulation is associated with tumor aggressiveness. To investigate the effects of DSPP-silencing on the tumorigenic profiles of the oral cancer cell line, OSC2, short-hairpin RNA (shRNA) interference was employed to silence DSPP in OSC2 cells.
    • Differential effects of taurine treatment and taurine deficiency on the outcome of renal ischemia reperfusion injury

      Mozaffari, Mahmood S.; Abdelsayed, Rafik; Patel, Champa; Wimborne, Hereward J. C.; Liu, Jun Yao; Schaffer, Stephen W; Department of Oral Biology; Department of Oral Health and Diagnostic Sciences (2010-08-24)
      Taurine possesses membrane stabilization, osmoregulatory and antioxidant properties, aspects of relevance to ischemic injury. We tested the hypothesis that body taurine status is a determinant of renal ischemic injury. Accordingly, renal function and structure were examined in control (C), taurine-treated (TT) and taurine deficient (TD) rats that were subjected to bilateral renal ischemia (60 min) followed by reperfusion (IR); sham operated rats served as controls. Baseline urine osmolality was greater in the TD group than in the control and the TT groups, an effect associated with increased renal aquaporin 2 level. The IR insult reduced urine osmolality (i.e., day-1 post insult); the TD/IR group displayed a more marked recovery in urine osmolality by day-6 post insult than the other two groups. Fluid and sodium excretions were lower in the TD/IR group, suggesting propensity to retention. Histopathological examination revealed the presence of tubular necrotic foci in the C/IR group than sham controls. While renal architecture of the TD/IR group showed features resembling sham controls, the TT/IR group showed dilated tubules, which lacked immunostaining for aquaporin 2, but not 1, suggestive of proximal tubule origin. Finally, assessment of cell proliferation and apoptosis revealed lower proliferation but higher apoptotic foci in the TT/IR group than other IR groups. Collectively, the results indicate that body taurine status is a major determinant of renal IR injury.
    • Direct Composite restorations Using a Clear PVS Matrix to restore Worn Anterior Dentition to Create an Ideal Occlusal Plane

      Fowlkes, Colton; Romero, M; Urbanawiz, D; Department of Restorative Sciences (Augusta University, 2019)
      This clicnical case documents the use of a clear PVS matrix technique to restore the incisal edges of worn mandibular anterior teeth using flowable composite to provide a 20 degree template for eventual complete maxillary denture and mandibular removable partial denture frabrication.
    • DNA Sequencing of Extensive Odontogenic Keratocysts with Possible Therapeutic Implications

      Abdelsayed, Macarius; Kolhe, Ravindra; Abdelsayed, Rafik; Department of Oral and Maxillofacial Pathology (Augusta University, 2019)
      Purpose of this research is: to perform DNA sequencing on a group of previously diagnosed OKC of the jaws which demonstrated clinical aggressive behavior; Compare the genetic profile of the aggressive OKC cases with the genetic profile of a similar number of OKC cases which did not demonstrate aggressive clinical behavior; Evaluate the possibility of therapeutic implications of genetic mutations noted in OKCs
    • Does Time to the Operating Room Affect Outcomes in Odontogenic Infection Patients?

      Brown, Kiara; James, Jeffery; Department of Oral and Maxillofacial Surgery (Augusta University, 2019)
      Diagnosis and treatments of odontogenic infections is arguably one of the most important responsibilities of the Oral and Maxillofacial Surgeon. With a command of the complex anatomy of the head and neck region and armed with knowledge of the dentition that feeds into the physiopathology of the infection, oral and maxillofacial surgeons find themselves one of the only head and neck specialists able to treat this disease. Several decades ago, odontogenic infections were a significant source of morbidity at rates greater than 50% in some reports. The current trend in an increase in unsponsored patients seeking treatment. This trend has cost hospital centers upwards of millions of dollars per year. While some factors, such as patient medical complexity and increasing antibiotic resistance are known factors in increasing costs, a surgeon and facility dependent factor- time to the operating room- has not been studied. Understanding the effect of delayed surgical intervention is critical to fully understanding ways to mitigate costs associated with odontogenic infection patients.
    • Ed Mills Interview

      Downing, Paul R (2011)
      This issue of the Palmetto Leaflet contains an interview with the Director of the MCG Dental Implant Maxi Course, Dr. Ed Mills.
    • Effect of an Er,Cr:YSGG Laser on P. Gingivalis-Contaminated Titanium Alloy Dental Implant Surfaces In Vitro

      Strever, Jason; Department of Oral Biology (2016-04)
      Implant dentistry has become a widely accepted modality to replace missing teeth. However, dental implants are susceptible to biofilm-mediated inflammatory lesions (peri-implant mucositis / peri-implantitis), similar to that seen around natural teeth (gingivitis / periodontitis). These lesions, in turn, threaten the longevity of implants as anchors for dental prostheses. Because of the similarity in etiology and presentation, comparable treatment modalities are applied to resolve peri-implant and periodontal inflammatory lesions. Such a shared treatment includes mechanical debridement, with or without surgical repositioning of the soft tissue complex. However, most contemporary dental implants feature threads to engage the alveolar bone and a micro/nano-textured surface to stimulate bone-implant contact (osseointegration). Therefore, when the implant threads become exposed and contaminated by biofilm, subsequent surface debridement / decontamination becomes considerably more complex than with that of a natural tooth, which is usually debrided using a metal curette or ultrasonic device. The micro/nano-textured surface of a dental implant is easily damaged by instrumentation using a metal curette. If an efficient method of dental implant surface decontamination could be established, then clinical protocols may be developed that effectively clean the implant surface to achieve peri-implant tissue health. To this end, lasers have been introduced; however, directly applied laser energy may also affect implant surface characteristics, including micro/nano-structure and composition, essential to osseointegration. Therefore, lasers may have disadvantageous clinical effects, in turn compromising peri-implant tissue consolidation and health: the very aspects its use is attempting to provide. Commercially available Er,Cr:YSGG lasers have been used to remove such implant-attached deposits, however the efficacy in removal of bacteria and the safety to the implant surface integrity have yet to be demonstrated quantitatively.
    • Effect of b-alanine treatment on mitochondrial taurine level and 5-taurinomethyluridine content

      Jong, Chian Ju; Ito, Takashi; Mozaffari, Mahmood S.; Azuma, Junichi; Schaffer, Stephen W; Department of Oral Biology (2010-08-24)
      Background: The b-amino acid, taurine, is a nutritional requirement in some species. In these species, the depletion of intracellular stores of taurine leads to the development of severe organ dysfunction. The basis underlying these defects is poorly understood, although there is some suggestion that oxidative stress may contribute to the abnormalities. Recent studies indicate that taurine is required for normal mitochondrial protein synthesis and normal electron transport chain activity; it is known that defects in these events can lead to severe mitochondrial oxidative stress. The present study examines the effect of taurine deficiency on the first step of mitochondrial protein synthesis regulation by taurine, namely, the formation of taurinomethyluridine containing tRNA.

      Abraham, Pheba; Abraham, Pheba; Department of Oral Biology (5/1/2017)
      This study was to explore the effect of local, matrix-bound bisphosphonates to monocytedifferentiation and osteoclast function in vitro. Experiments were designed using osteoassay plates. Cell-viability, differentiation, resorption pits and gene expression were analyzed to see the effect of matrix-bound BPs on monocyte differentiation and osteoclast function. EDTA was used as a chelating agent to remove the bound BPs. There was a dose dependent response in the differentiation and resorption pits. With chelation, there was increase in differentiation, resorption pits and increase in the calcium and PYD in the supernatant. Thus, matrix-bound Bisphosphonatesare biologically active and they inhibit monocyte differentiation and osteoclast function. Thereby removal of this matrix-bound drug can rescue osteoclast differentiation and function.