Microbiological cleaning and disinfection efficacy of a three-stage ultrasonic processing protocol for CAD-CAM implant abutments

Gehrke, Peter,Riebe, Oliver,Fischer, Carsten,Weinhold, Octavio,Dhom, Gunter,Sader, Robert,Weigl, Paul The Korean Academy of Prosthodonitics 2022 The Journal of Advanced Prosthodontics Vol.14 No.5

PURPOSE. Computer-aided design and manufacturing (CAD-CAM) of implant abutments has been shown to result in surface contamination from site-specific milling and fabrication processes. If not removed, these contaminants can have a potentially adverse effect and may trigger inflammatory responses of the peri-implant tissues. The aim of the present study was to evaluate the bacterial disinfection and cleaning efficacy of ultrasonic reprocessing in approved disinfectants to reduce the microbial load of CAD-CAM abutments. MATERIALS AND METHODS. Four different types of custom implant abutments (total N = 32) with eight specimens in each test group (type I to IV) were CAD-CAM manufactured. In two separate contamination experiments, specimens were contaminated with heparinized sheep blood alone and with heparinized sheep blood and the test bacterium Enterococcus faecium. Abutments in the test group were processed according to a three-stage ultrasonic protocol and assessed qualitatively and quantitatively by determination of residual protein. Ultrasonicated specimens contaminated with sheep blood and E. faecium were additionally eluted and the dilutions were incubated on agar plates for seven days. The determined bacterial counts were expressed as colony-forming units (CFU). RESULTS. Ultrasonic reprocessing resulted in a substantial decrease in residual bacterial protein to less than 80 ㎍ and a reduction in microbiota of more than 7 log levels of CFU for all abutment types, exceeding the effect required for disinfection. CONCLUSION. A three-stage ultrasonic cleaning and disinfection protocol results in effective bacterial decontamination. The procedure is reproducible and complies with the standardized reprocessing and disinfection specifications for one- or two-piece CAD-CAM implant abutments.

Microscopical and chemical surface characterization of CAD/CAM zircona abutments after different cleaning procedures. A qualitative analysis

Gehrke, Peter,Tabellion, Astrid,Fischer, Carsten The Korean Academy of Prosthodonitics 2015 The Journal of Advanced Prosthodontics Vol.7 No.2

PURPOSE. To describe and characterize the surface topography and cleanliness of CAD/CAM manufactured zirconia abutments after steaming and ultrasonic cleaning. MATERIALS AND METHODS. A total of 12 ceramic CAD/CAM implant abutments of various manufacturers were produced and randomly divided into two groups of six samples each (control and test group). Four two-piece hybrid abutments and two one-piece abutments made of zirconium-dioxide were assessed per each group. In the control group, cleaning by steam was performed. The test group underwent an ultrasonic cleaning procedure with acetone, ethyl alcohol and antibacterial solution. Groups were subjected to scanning electron microscope (SEM) analysis and Energy-dispersive X-ray spectroscopy (EDX) to verify and characterize contaminant chemical characterization non- quantitatively. RESULTS. All zirconia CAD/CAM abutments in the present study displayed production-induced wear particles, debris as well as organic and inorganic contaminants. The abutments of the test group showed reduction of surface contamination after undergoing an ultrasonic cleaning procedure. However, an absolute removal of pollutants could not be achieved. CONCLUSION. The presence of debris on the transmucosal surface of CAD/CAM zirconia abutments of various manufacturers was confirmed. Within the limits of the study design, the results suggest that a defined ultrasonic cleaning process can be advantageously employed to reduce such debris, thus, supposedly enhancing soft tissue healing. Although the adverse long-term influence of abutment contamination on the biological stability of peri-implant tissues has been evidenced, a standardized and validated polishing and cleaning protocol still has to be implemented.

Influence of scaling procedures on the integrity of titanium nitride coated CAD/CAM abutments

Peter Gehrke,Emmanouil Spanos,Carsten Fischer,Helmut Storck,Florian Tebbel,Dirk Duddeck 대한치과보철학회 2018 The Journal of Advanced Prosthodontics Vol.10 No.3

PURPOSE. To determine the extent of treatment traces, the roughness depth, and the quantity of titanium nitride (TiN) removed from the surface of CAD/CAM abutments after treatment with various instruments. MATERIALS AND METHODS. Twelve TiN coated CAD/CAM abutments were investigated for an in vitro study. In the test group (9), each abutment surface was subjected twice (150 g vs. 200 g pressure) to standardized treatment in a simulated prophylaxis measure with the following instruments: acrylic scaler, titanium curette, and ultrasonic scaler with steel tip. Three abutments were used as control group. Average surface roughness (Sa) and developed interfacial area ratio (Sdr) of treated and untreated surfaces were measured with a profilometer. The extent of treatment traces were analyzed by scanning electron microscopy. RESULTS. Manipulation with ultrasonic scalers resulted in a significant increase of average surface roughness (Sa, P<.05) and developed interfacial area ratio (Sdr, P<.018). Variable contact pressure did not yield any statistically significant difference on Sa-values for all instruments (P=.8). Ultrasonic treatment resulted in pronounced surface traces and partially detachment of the TiN coating. While titanium curettes caused predominantly moderate treatment traces, no traces or detectable substance removal has been determined after manipulation with acrylic curettes. CONCLUSION. Inappropriate instruments during regular plaque control may have an adverse effect on the integrity of the TiN coating of CAD/CAM abutments. To prevent defects and an increased surface roughness at the transmucosal zone of TiN abutments, only acrylic scaling instruments can be recommended for regular maintenance care.

Assessing the importance of housing, accessibility, and transportation characteristics on stated neighbourhood preference

Steven R. Gehrke,Kristina M. Currans,Kelly J. Clifton 서울시립대학교 도시과학연구원 2019 도시과학국제저널 Vol.23 No.1

Beyond socioeconomic circumstance, residential location decisions are also predicated on many housing, transportation, and accessibility characteristics. Consequently, greater insight is needed on how these myriad characteristics are valued by individuals and connected to their neighbourhood preference to inform planners and decision makers concerned with urban growth patterns. Unfortunately, forecasting methods commonly lack the specificity needed to recognize how residential environment preferences influence future housing, land use, and transportation decisions. Often, these policy instruments rely exclusively on a set of observed socioeconomic characteristics to measure heterogeneity in revealed location decisions. Using stated preference data collected in Portland, Oregon, this study employed structural equation modelling techniques to examine the influence of these socioeconomic measures and latent constructs of rated single-family dwelling and non-automotive access importance on stated neighbourhood preference. Our study's findings suggest the importance placed on certain bundles of housing, transportation, and accessibility attributes, and not socioeconomic circumstance, directly affected neighbourhood preference.

Early complications and performance of 327 heat-pressed lithium disilicate crowns up to five years

Fabian Huettig,Ulf Peter Gehrke 대한치과보철학회 2016 The Journal of Advanced Prosthodontics Vol.8 No.3

PURPOSE The prospective follow-up aimed to assess the performance of lithium disilicate crowns and clinical reasons of adverse events compromising survival and quality. MATERIALS AND METHODS 58 patients were treated with 375 heat-pressed monolithic crowns, which were bonded with resin cement. Annual recalls up to five years included a complete dental examination as well as quality assessment using CDA-criteria. Any need for clinical intervention led to higher complication rate and any failure compromised the survival rate. Kaplan-Meier-method was applied to all crowns and a dataset containing one randomly selected crown from each patient. RESULTS Due to drop-outs, 45 patients (31 females, 14 males) with the average age of 43 years (range = 17–73) who had 327 crowns (176 anterior, 151 posterior; 203 upper jaw, 124 lower jaw) were observed and evaluated for between 4 and 51 months (median = 28). Observation revealed 4 chippings, 3 losses of retention, 3 fractures, 3 secondary caries, 1 endodontic problem, and 1 tooth fracture. Four crowns had to be removed. Survival and complication rate was estimated 98.2% and 5.4% at 24 months, and 96.8% and 7.1% at 48 months. The complication rate was significantly higher for root canal treated teeth (12%, P<.01) at 24 months. At the last observation, over 90% of all crowns showed excellent ratings (CDA-rating Alfa) for color, marginal fit, and caries. CONCLUSION Heat pressed lithium disilicate crowns showed an excellent performance. Besides a careful luting, dentists should be aware of patients' biological prerequisites (grade of caries, oral hygiene) to reach full success with these crowns

Management of Gonarthrosis with a Rotating Hinge Prosthesis: Minimum 10-Year Follow-up

Daniel Kendoff,Carl Haasper,Thorsten Gehrke,Wolfgang Klauser,Nemandra Sandiford,FRCS (Tr/Orth) 대한정형외과학회 2020 Clinics in Orthopedic Surgery Vol.12 No.4

Background: The use of hinged designs is usually reserved for severe deformities or instability in contemporary total knee arthroplasty (TKA). Results have been mixed with some authors reporting relatively high incidences of complications. The aim of this study is to present the results of primary TKA performed with a hinged prosthesis with a minimum 10-year follow-up. We also examined the factors that influence survivorship of this prosthesis. Methods: A total of 238 primary TKA procedures were performed using hinged prostheses. Indications included osteoarthritis, rheumatoid arthritis, posttraumatic deformity, and arthritis. Clinical outcomes were assessed using the Hospital for Special Surgery score. Radiologic assessment was performed at each follow-up. Survivorship was calculated based on the Kaplan-Meier method. All complications were documented. Results: Mean follow-up was 13.5 years (standard deviation [SD], 3.4). Mean flexion at final review was 118° (SD, 20°). Fifty-four percent and 20% reported excellent and good functional scores, respectively. Survivorship was 94% at 13.5 years in patients over 60 years of age and 77% in patients less than 60 years of age. Survivorship in patients with preoperative varus deformity was 96% and that in valgus knees was 79%. Conclusions: The results of this study suggest that when rotating hinges are used for primary TKA, the best results are achieved in patients over 60 years old. The indications for this design in the setting of primary TKA include significant deformities, severe bone loss, and ligamentous laxity.

Microscopical and chemical surface characterization of CAD/CAM zircona abutments after different cleaning procedures. A qualitative analysis

Astrid Tabellion,Carsten Fischer,Peter Gehrke 대한치과보철학회 2015 The Journal of Advanced Prosthodontics Vol.7 No.2

PURPOSE To describe and characterize the surface topography and cleanliness of CAD/CAM manufactured zirconia abutments after steaming and ultrasonic cleaning. MATERIALS AND METHODS A total of 12 ceramic CAD/CAM implant abutments of various manufacturers were produced and randomly divided into two groups of six samples each (control and test group). Four two-piece hybrid abutments and two one-piece abutments made of zirconium-dioxide were assessed per each group. In the control group, cleaning by steam was performed. The test group underwent an ultrasonic cleaning procedure with acetone, ethyl alcohol and antibacterial solution. Groups were subjected to scanning electron microscope (SEM) analysis and Energy-dispersive X-ray spectroscopy (EDX) to verify and characterize contaminant chemical characterization non-quantitatively. RESULTS All zirconia CAD/CAM abutments in the present study displayed production-induced wear particles, debris as well as organic and inorganic contaminants. The abutments of the test group showed reduction of surface contamination after undergoing an ultrasonic cleaning procedure. However, an absolute removal of pollutants could not be achieved. CONCLUSION The presence of debris on the transmucosal surface of CAD/CAM zirconia abutments of various manufacturers was confirmed. Within the limits of the study design, the results suggest that a defined ultrasonic cleaning process can be advantageously employed to reduce such debris, thus, supposedly enhancing soft tissue healing. Although the adverse long-term influence of abutment contamination on the biological stability of peri-implant tissues has been evidenced, a standardized and validated polishing and cleaning protocol still has to be implemented.

The <i>bantam</i> microRNA acts through Numb to exert cell growth control and feedback regulation of Notch in tumor-forming stem cells in the <i>Drosophila</i> brain

Wu, Yen-Chi,Lee, Kyu-Sun,Song, Yan,Gehrke, Stephan,Lu, Bingwei Public Library of Science 2017 PLoS genetics Vol.13 No.5

<▼1><P>Notch (N) signaling is central to the self-renewal of neural stem cells (NSCs) and other tissue stem cells. Its deregulation compromises tissue homeostasis and contributes to tumorigenesis and other diseases. How N regulates stem cell behavior in health and disease is not well understood. Here we show that N regulates <I>bantam</I> (<I>ban</I>) microRNA to impact cell growth, a process key to NSC maintenance and particularly relied upon by tumor-forming cancer stem cells. Notch signaling directly regulates <I>ban</I> expression at the transcriptional level, and <I>ban</I> in turn feedback regulates N activity through negative regulation of the Notch inhibitor Numb. This feedback regulatory mechanism helps maintain the robustness of N signaling activity and NSC fate. Moreover, we show that a Numb-Myc axis mediates the effects of <I>ban</I> on nucleolar and cellular growth independently or downstream of N. Our results highlight intricate transcriptional as well as translational control mechanisms and feedback regulation in the N signaling network, with important implications for NSC biology and cancer biology.</P></▼1><▼2><P><B>Author summary</B></P><P>Stem cells are functional units in the development, maintenance, and regeneration of tissues in multicellular organisms. Defects in stem cell regulation can compromise tissue homeostasis and result in proliferative or degenerative diseases. Our understanding of the molecular and cellular mechanisms regulating the <I>in vivo</I> behavior of stem cells is still incomplete. The <I>Drosophila</I> central nervous system neural stem cells called neuroblasts have offered an excellent model system for uncovering key mechanisms and player involved in stem cell regulation. Previous genetic studies have uncovered the evolutionarily conserved Numb-N signaling pathway that regulates the self-renewal vs. differentiation choices of the cell fates of NSCs during their asymmetric division. Our understanding of how Numb-N signaling regulates NSC fate is still rudimentary. Recent studies have implicated the involvement of microRNAs in stem cell regulation in both mammalian and <I>Drosophila</I> systems. But the molecular mechanism and logic of miRNA action remain to be delineated. In this study we show that the <I>bantam</I> microRNA is a direct transcriptional target of the N signaling pathway, and that <I>bantam</I> feedback regulates N by negatively regulating the expression of Numb, an inhibitor of N. This feedback regulation of N helps maintain the robustness of NSC fate. We further show that <I>bantam</I> also impinges on a Numb-Myc axis of cell growth regulation, apparently in a N-independent manner. Together, our results highlight the importance of both transcriptional and translational control mechanisms in NSC regulation by the N signaling network. These findings have important implication for our understanding of the basic biology of NSCs and the therapeutic intervention of N-induced cancers.</P></▼2>

Impact of Different Implant Surfaces Topographies on Peri-Implant Tissues: An Update of Current Available Data on Dental Implants Retrieved from Human Jaws

A. Shibli, Jamil,T. Pires, Jefferson,Piattelli, Adriano,Iezzi, Giovanna,Mangano, Carlo,Mangano, Francesco,L.S. de Souza, Sergio,A. Gehrke, Sergio,Wang, Hom-Lay,M. Dohan Ehrenfest, David Bentham Science Publishers Ltd. 2017 CURRENT PHARMACEUTICAL BIOTECHNOLOGY Vol. No.