Histomorphological Comparison of Platelet Rich Fibrin Combinations for Ridge Preservation.

PosterBackground: Most commonly used techniques to preserve ridge dimensions following tooth extraction involve bone substitutes and membranes to cover the graft. The use of autologous Platelet Rich Fibrin (PRF) is a recent introduction to be used as a membrane as well as mixed with the graft material. PRF is an inexpensive autologous gel enriched with platelets from venous blood that is easily processed in a clinical setting and contains growth factors including PDGF, TGF-β, VEGF, EGF and IGF1. The aim of this case report is to compare the histomorphologic results of various combinations of PRF, freeze dried bone allograft (FDBA) and polylactic acid membranes (Guidor) in extraction sockets in a single patient. Material and Methods: A 49-year old female patient with a 12 pack-year smoking history presented for extraction of maxillary teeth for an implant retained complete denture. On the day of surgery, 40ml of venous blood was drawn and centrifuged to produce four PRF gels. Two PRF gels were minced and mixed with FDBA. Two clots were processed to be used as membranes to cover the sockets. Teeth #s 4, 6, 11, and 13 were extracted with minimal trauma and sockets were thoroughly debrided. Varying combination of FDBA, PRF, and Guidor membranes were used for ridge preservation grafting in the four sockets. Four and half months following extraction, trephine cores were taken at the time of implant placement and submitted for histological analysis. Results: Clinical healing was uneventful at all sockets but soft tissue healing appeared slightly rapid on sites covered with PRF membranes. However, histologic healing showed more vital bone formation around residual graft materials with Guidor membranes sites. Conclusions: Within the limits of this case report, although PRF membranes seemed to slightly enhance soft tissue healing, the use of Guidor membranes appeared to improve bone remodeling

Experimental Evaluation Of The Frost Formation

Frost formation on an evaporator causes a significant problem increasing thermal resistance, resulting in a decrease in system performance. It is important for an improvement in system performance under low-temperature to?predict the frost formation. We measured the weight and height of frost layer on a cold surface in different inlet air conditions, cold surface temperatures, inlet air velocities. We derived the frost density and demonstrated the dominant factors of the frost density

A Necessary and Sufficient Condition for the Existence of an (n,r)-arc in PG(2,q) and Its Applications

ACM Computing Classification System (1998): E.4.Let q be a prime or a prime power ≥ 3. The purpose of this paper is to give a necessary and sufficient condition for the existence of an (n, r)-arc in PG(2, q ) for given integers n, r and q using the geometric structure of points and lines in PG(2, q ) for n > r ≥ 3. Using the geometric method and a computer, it is shown that there exists no (34, 3) arc in PG(2, 17), equivalently, there exists no [34, 3, 31] 17 code.This research was partially supported by Grant-in-Aid for Scientific Research of Japan Society for the Promotion of Science under Contract Number 24540138

Biomechanical and histological evaluation of a new zirconia implant in a canine model

Indiana University-Purdue University Indianapolis (IUPUI)Background: Currently titanium implant fixtures are considered as a gold standard because of their biocompatibility and their clinical success rates have been well documented. The esthetic outcome of restorations supported by titanium implants may be compromised if the dark gray color of the implant shows through a thin peri-implant mucosa or if the implant fixture becomes visible following soft tissue recession. Also titanium might cause allergic reactions. For these reasons, zirconia implants have been considered as alternative materials because of their white color, high material properties and biocompatibilities. Still, further investigations are necessary to confirm the in-vivo performance of these implants. Purpose: The purpose of this study is to determine the histomorphometric and biomechanical properties of zirconia implants manufactured by Shofu Inc. with a sand-blasted and acid-etched surface treatment, compared to that of the titanium implants from the same manufacturer with a sand-blasted and acid-etched surface treatment in a canine model. Material and Methods: Six beagle dogs (1-2 years old) will be used in this split mouth trial. After 8 weeks following extraction of the second to fourth mandibular premolars, zirconia implants (experimental group) and titanium implants (control group) were placed on the each side of mandible. At 8 weeks and 12 weeks after implant placement, the animals were sacrificed, and implants were removed in block sections, and histological and histomorphometric analyses were measured. Specifically, the bone-implant contact (BIC), bone area (BA), removal torque (RTQ), mineral apposition rate (MAR), bone forming area (BFA), and Periotest value (PTV) of the two groups were studied and compared. Results: At 12 weeks post operatively, one Shofu thread type Ti implant were not integrated. Over all failure implant was 0/12 in zirconia group, and 1/12 in titanium group. In 8 weeks samples, only statistical differences were higher BA (p=0.02) in macro threads area and BFA (p=0.02) in zirconia implants group than titanium implants group. In 12 weeks group, zirconia implant group showed higher MAR at 9-10 and 10-11weeks time frame (p=0.02, and 0.04 restectively), and PVT value (p=0.01) than titanium implants group. Removal torque value increased in both titanium and zirconia group with time. Average of removal torque value showed higher in titanium implants than zirconia implants, but the differences were not statistically significant in both 8 weeks (Ti; 64.16±16.93 N-cm, ZrO₂: 42.5±6.01 N-cm : p=0.247) and 12 weeks (Ti; 82.5±9.41 N-cm, ZrO₂: 51.3±19.38 N-cm: p=0.16). In the removal torque analysis, it is observed that the bone-implant interface seems to be of more rigid and brittle in nature as indicated by the lower averaged onset angle, peak angle, area under curve and RTQ. Conclusion: Zirconia implants group showed higher value of BA with macro thread and BFA in 8weeks and MAR at 9-10, 10-11 weeks period, and PVT in 12 weeks post operatively. Within the limited number of samples tested in this study, there is no difference between the BIC and RTQ of zirconia and titanium implants after 8 and 12 weeks of implantation

Assessing the Medical Emergency Preparedness of Dental Faculty, Residents, and Practicing Periodontists: An Exploratory Study

With the increased number of elderly and medically compromised individuals receiving dental care and the presence of systemic comorbidities and associated treatment modalities in this patient population, it is imperative that dentists be prepared to manage a variety of medical emergencies. The aim of this study was to assess the knowledge of and preparedness to manage common medical emergencies of cohorts of practicing periodontists, specialty residents, and faculty members, both for comparative purposes and as an aid to refining a dental school’s standardized case scenarios. The study, conducted in 2017, was designed for four groups of randomly selected participants with at least 20 in each group; the actual number of voluntary participants was 28 private practice periodontists, 22 residents in specialty programs, 21 specialist faculty members, and 24 general practice faculty members. Participants were asked to evaluate ten clinical emergency cases and identify the diagnosis and indicated intervention for each. Groups were also evaluated for differences among correct responses for each case. Overall, there were no statistically significant differences for number of correct diagnoses or interventions among the four groups. However, several cases had varying degrees of incorrect diagnoses and management across all groups. Participants who had recently graduated or were still in school were able to treat cases appropriately more often than the other participants. Further refinement of cases to assess provider preparedness to correctly diagnose and manage medical emergencies is needed, specifically establishing case-specific features and addressing areas of potential confusion before the cases are used for educational purposes

Congenital prepubic sinus: A case report and review of the literature

AbstractCongenital prepubic sinus (CPS) is an extremely rare anomaly, which is often associated with purulent discharge from a midline opening overlying the pubis. CPS was first described by Campbell et al. in 1987 and they suggested that it might represent a variation in normal embryological development. Several theories have been proposed regarding the pathogenesis of CPS. However, the etiology of CPS is still unclear because the anatomical and pathological features of CPS often differ from each other. We report a case of CPS and review the literature to improve the global understanding of CPS

Assessing Effectiveness of an Audiovisual Educational Tool for Improving Dental Students' Probing Depth Consistency

Dental students often underestimate their probing depth (PD) measurements, which emphasizes the need for effective and novel methods for teaching proper probing technique. The aim of this study was to evaluate the efficacy of audiovisual learning aids, recorded from the point of view of examiners, for improvement in PD agreement in dental students. In 2017‐18, 22 third‐year dental students were randomized into test and control groups. Each student and a single blinded faculty examiner performed PD measurements on a minimum of three patients. The test group viewed a video demonstrating proper probing technique, while the control group received only probing technique instruction from prior lectures. All measurements, the periodontal diagnoses, and the total time taken to complete PD measurements were recorded. A survey of student attitudes about the audiovisual tool was conducted after the intervention; all 22 students completed the survey. A total of 11,426 PD sites were measured. The test group had 10% greater accuracy in PD sites=4 mm. The control group had a minor but statistically significant increase in accuracy for 2 mm PD sites. For all incorrect measurements at sites PD≥4, the students tended to underestimate the PD. Tooth type, site location around tooth, and diagnosis had no significant effect on PD measurement agreement. No significant difference between groups was found for the proportions of gingivitis and periodontitis patients or for examination time. This study found that use of the audiovisual learning aid “Calibrated Periodontal Training Video” improved the students' probing depth accuracy for sites with PD of 4 mm

Levels of growth factors from platelet-rich fibrin from chronic periodontitis versus periodontally healthy subjects: a pilot study

Objectives This study aimed to (1) compare the amounts of growth factors from platelet-rich fibrin (PRF) between chronic periodontitis and periodontally healthy subjects and (2) evaluate the relationships between the amounts of growth factors from PRF with complete blood counts (white blood cell (WBC) and platelet counts) and the serum concentrations of IL-1β, IL-6, and tumor necrosis factor-α (TNF-α). Materials and methods Venous blood was collected from chronic periodontitis (test) and periodontally healthy subjects (control). PRF and serum were collected from the centrifuged blood. Liquid exudates from the compression of PRF were collected. The compressed PRF membranes were incubated in saline, and eluted aliquots were collected at 1, 24, and 72 h, and the membranes were then digested with trypsin. Epidermal growth factor, insulin-like growth factor-1, platelet-derived growth factor-BB, transforming growth factor-β1, and vascular endothelial growth factor in the exudates and eluents were quantified by ELISA. Serum was used for IL-1β, IL-6, and TNF-α quantifications. Complete blood counts were measured. Results There were no significant differences in the amounts of growth factors from PRF exudates and membranes measured between groups (all p > 0.05). The test group had significantly higher WBC (p  0.05). Conclusions PRF can be utilized as an autologous source of growth factors not affected by periodontal condition and WBC level