Surface Of Prosthesis Research Articles

Open-source hand prosthesis: evaluation of mechanical feasibility and additive manufacturing potential

This study delves into the risks associated with 3D-printed hand prostheses lacking mechanical feasibility studies. Such unvalidated prostheses may exhibit various issues like durability shortcomings, anatomical incompatibility, functional safety concerns, manufacturing quality deficiencies, and health risks due to inappropriate materials. These issues can lead to damage or premature failure during use, discomfort, skin irritation, injuries, inability to withstand functional loads, and health hazards from toxic or allergenic substances. Therefore, ensuring the safety, quality, and effectiveness of these prostheses is crucial. The study focuses on a mechanical feasibility study conducted through Finite Element Analysis (FEA) simulations on an open-source hand prosthesis model. It evaluates mechanical properties, stress concentration areas, and displacement on the prosthesis surface. The methodology comprises three key steps: acquiring the virtual model, conducting computational simulations, and selecting the 3D printing material. The simulations assess the prosthesis’s ability to withstand compressive forces and identify stress concentration areas. Results from the study indicate that using PETG as the constituent material demonstrates mechanical viability and satisfactory performance under static force conditions. This finding underscores the importance of rigorous testing and adherence to standards in developing 3D-printed hand prostheses. Such studies contribute significantly to enhancing these devices’ safety and effectiveness, facilitating their broader adoption in healthcare settings. In summary, this study highlights the critical need for mechanical feasibility studies in the development of 3D-printed hand prostheses. It emphasizes the significance of following strict standards and regulations to ensure these devices’ safety, quality, and functionality. By doing so, it paves the way for the widespread use of these prostheses in healthcare, benefiting users and advancing the field of prosthetic technology.

Minocycline-rifampin-impregnated penile prosthesis surfaces retain antimicrobial activity following irrigation with 0.05% chlorhexidine gluconate and antibiotic solutions.

0.05% Chlorhexidine gluconate (CHG; Irrisept [IrriMax]) is a commercial wound irrigation solution approved by the Food and Drug Administration that has seen recent adoption in the field of prosthetic urology; however, no study has evaluated whether 0.05% CHG is compatible with the minocycline-rifampin-impregnated surface (InhibiZone) of the AMS 700 penile prosthesis (Boston Scientific). To evaluate whether 0.05% CHG alters the antibiotic efficacy of the minocycline-rifampin-impregnated penile prosthesis surface. Discs (8 mm) were taken by a punch biopsy (Sklar) from sterile penile prosthesis reservoirs whose surfaces had been impregnated with rifampin and minocycline. Discs (n = 10) were suspended in 0.05% CHG, vancomycin and gentamicin, or normal saline for 2minutes to simulate intraoperative irrigation. Discs were then rinsed in normal saline to remove any unbound solution and incubated with methicillin-sensitive Staphylococcus aureus for 48hours. Adherent surface bacteria were suspended by shaking in a 0.3% Tween 20 solution, serially diluted, plated onto 3M PetriFilms, and counted. Kirby-Bauer disc diffusion assays were conducted to generalize findings across various organisms. Outcomes included (1) bacterial adherence to the implant surface measured as bacterial counts (in colony-forming units per milliliter) and (2) bacterial growth reduction measured as zones of inhibitions (in millimeters). Incubation of implant surfaces in 0.05% CHG did not alter recovered bacterial counts as compared with normal saline and vancomycin/gentamycin. Similarly, within a single bacterial species, 0.05% CHG and vancomycin/gentamycin did not alter zone-of-inhibition measurements in Kirby-Bauer disc diffusion studies. This study demonstrates in vitro that 0.05% CHG may be used directly on the minocycline-rifampin-impregnated surface without altering the antibiotic efficacy of the coating. Strengths include that this is the first study to evaluate if 0.05% CHG affected the minocycline-rifampin-impregnated surface. Limitations include the use of in vitro studies, which serve as a proxy for in vivo practices and may not be entirely accurate or translatable in a clinical setting. 0.05% CHG does not alter the antimicrobial activity of the minocycline-rifampin-impregnated surface as compared with vancomycin/gentamycin and normal saline in vitro; however, its efficacy in clinical practice remains to be evaluated.

Comparison of the Impact of NaIO4-Accelerated, Cu2+/H2O2-Accelerated, and Novel Ion-Accelerated Methods of Poly(l-DOPA) Coating on Collagen-Sealed Vascular Prostheses: Strengths and Weaknesses.

Sensitive biomaterials subjected to surface modification require delicate methods to preserve their structures and key properties. These include collagen-sealed polyester vascular prostheses. For their functionalization, coating with polycatecholamines (PCAs) can be used. PCAs change some important biological properties of biomaterials, e.g., hydrophilicity, bioactivity, antibacterial activity, and drug binding. The coating process can be stimulated by oxidants, organic solvents, or process conditions. However, these factors may change the properties of the PCA layer and the matrix itself. In this work, collagen-sealed vascular grafts were functionalized with a poly(l-DOPA) (PLD) layer using novel seawater-inspired ion combination as an accelerator, compared to the sodium periodate, Cu2+/H2O2 mixture, and accelerator-free reference methods. Then, poly(l-DOPA) was used as the interface for antibiotic binding. The coated prostheses were characterized (SEM, FIB-SEM, FTIR, UV/vis), and their important functional parameters (mechanical, antioxidant, hemolytic, and prothrombotic properties, bioactivity, stability in human blood and simulated body fluid (SBF), antibiotic binding, release, and antibacterial activity) were compared. It was found that although sodium periodate increased the strength and drug-binding capacity of the prosthesis, it also increased the blood hemolysis risk. Cu2+/H2O2 destabilized the mechanical properties of the coating and the graft. The seawater-inspired ion-accelerated method was efficient, stable, and matrix- and human blood-friendly, and it stimulated hydroxyapatite formation on the prosthesis surface. The results lead to the conclusion that selection of the PCA formation accelerator should be based on a careful analysis of the biological properties of medical devices. They also suggest that the ion-accelerated method of PLD coating on medical devices may be highly effective and safer than the oxidant-accelerated coating method.

Impact of Hematoma on Capsular Contracture: A Comparative Study of Smooth and Textured Implants in a Miniature Pig Model.

Capsular contracture is a significant complication following mammaplasty, with varying incidence rates and symptoms. The etiology of capsular contracture is multifactorial, with postoperative hematoma recognized as a potential contributing factor. In this study we aimed to investigate the impact of postoperative hematoma on capsular contracture following mammaplasty, utilizing pig models and modified biomechanical testing. We sought to compare the severity of capsular contracture between smooth and textured implants in the presence of hematoma, assess the biomechanical properties of the capsules, and explore the histological and molecular changes associated with the condition. The study involved 5 female miniature pigs, implanted with both smooth and textured implants. Hematoma models were established, and various methods were employed to evaluate the impact of the prosthesis surface and hematoma on capsular contracture, including ultrasound assessment, biomechanical tests, scanning electron microscopy, histological analysis, and transcriptome sequencing. Capsules in hematoma groups were classified as Baker III/IV, with significantly unfavorable thickness, elastic modulus, and relaxation and creep amounts compared to nonhematoma groups. Smooth implants under hematoma conditions exhibited increased muscle content and biomechanical strength of the capsule. Transcriptomic analysis highlighted differential gene expression related to muscle development and contraction in smooth implants with hematomas. Hematomas increase the risk of capsular contracture, with smooth implants exacerbating this effect by enhancing pathways related to muscle development and contraction. This underscores the importance of hematoma prevention and treatment strategies, particularly when placing smooth implants, to minimize the occurrence of capsular contracture. The study provides insights into the mechanisms underlying capsular contracture and offers evidence to guide surgical and postoperative management strategies.

Cytological and Cytometric Analysis of Epithelial Cell Changes Under the Surface of Acrylate Prosthesis in Diabetic Patients

Background: The aim of this study was to assess cytological alterations of the squamous epithelium of the alveolar ridge mucosal surface under the acrylate prosthesis in T2D patients. Methods and Results: The subjects of interest were patients in whom the total acrylate prosthesis had been applied 3-5 years or more prior to the examination. The subjects were divided into two groups: 30 adult subjects with T2D (T2D group) and 30 adult subjects without T2D (control group). Both groups were over 49 years of age. Cytological smears were obtained by cytobrush from the mucosal surface of the gingival crest underlying the acrylate prosthesis. The following parameters were assessed: type of cells (basal, intermediate, superficial, superficial without nucleus, and parakeratotic), proportions of the types of cells, cytoplasmic diameter, nuclear diameter, and nucleus-to-cytoplasm ratio. An independent sample t-test was used to compare the two study groups. The percentage of superficial cells was significantly lower in the T2D group than in the control group (P=0.001). The T2D group tended to have a higher rate of parakeratotic cells (13.0±11.12 vs. 8.07±7.92, P=0.052). Superficial cells in the T2D group had a significantly lower mean cytoplasmic diameter than the control group (32.7947±8.61929 µ vs. 36.6383±4.32228 µ, P=0.03). Additionally, the nucleus-to-cytoplasm ratio of intermediate and superficial cells in the T2D group was significantly higher than in the control group (0.2407±0.07206 vs. 0.2000±o.03291, P=0.007 and 0.2573±0.06330 vs. 0.2280±0.03178, P=0.027). Conclusion: The results of our study show that total acrylate prostheses in diabetic patients are responsible for the disrupted maturation of squamous epithelial cells. This is reflected in smaller superficial cells, increased parakeratosis, and the higher nucleus-to-cytoplasm ratio of intermediate and superficial cells.

INDEX-BASED ASSESSMENT ALGORITHM FOR ORAL HYGIENE IN WEARERS OF FIXED DENTAL BRIDGES

Introduction: The study focuses on the importance of maintaining oral hygiene, especially in wearers of fixed dental bridge. The impact of inadequate oral hygiene care on the development of dental diseases and the necessity for developing effective methods for its assessment are examined. Research objective: The aim of this study is to refine the fluorescent diagnostic method in orthopedic dentistry and to develop an index for assessing the hygienic status of natural teeth and fixed dental prostheses through an in vivo experiment. This method is intended to improve the diagnosis of oral conditions in wearers of fixed prostheses, ultimately enhancing the quality of their orthopedic treatment. Materials and methods: The study is based on the application of fluorescent diagnostics using Rhodamine B dye, which, when exposed to ultraviolet light, allows for the detection of dental deposits. The technique involves treating the surfaces of teeth and prostheses with a special solution that enhances the visibility of dental plaque under ultraviolet illumination. Research results: The experimental results demonstrated the high efficiency of the fluorescent method in detecting dental deposits both on the enamel of natural teeth and on the ceramic surface of fixed dentures. The digital analysis method allows for obtaining specific graphical indicators of the biofilm area, enhancing the relevance of an individual approach. Conclusions: Conclusions: The experimental study confirmed the high efficiency of the refined fluorescent method for assessing the hygienic status of the oral cavity, applicable to both natural teeth and fixed orthopedic constructions. This technique enables accurate assessment of hygiene status, facilitating effective prevention of dental diseases and optimization of treatment procedures. The method is convenient to use, and the software is accessible for clinicians. Further observations on the outcomes of this technique in patients with various orthopedic profiles are planned to expand its applicability.

DETECTION OF BIOFILM PRODUCTION FOR ORAL BACTERIAL ISOLATES AND IT’S IMPACT ON DENTAL CARIES OCCURANCE

Background and aims: Microorganisms are known to be involved in the formation of biofilms. These biofilms are often seen in the oral cavity, tooth surfaces, prosthesis surfaces, attached oral mucosa, dental implants, etc. These are capable of causing dental caries or gingivitis, and most of them are also known to possess a higher ability to cause dental caries than non-biofilm-producing bacteria. This study was conducted to detect the biofilm formation in bacterial isolates from the oral cavity of patients attaining dental clinics in the Faculty of Dentistry, Sana’a University. In addition, the study examined the association between DMFT, decay, missing teeth due to caries, and filled teeth in the permanent teeth and the degree of bacteria ability to produce biofilm. Materials and Methods: Biofilm production was performed on 294 oral bacteria isolates from 100 patients who visited dental clinics run by Sana'a University's Faculty of Dentistry and private dental clinics. Biofilm-forming oral bacteria were detected by the tissue culture plate (TCA) method. The impact of biofilm production was correlated with the DMFT index of the tested patients. Results: Out of 294 isolates, biofilm formation was seen in 285 isolates (96.9%) by the TCP method. 21.4% of the iosolates showed a weak ability to produce biofilms, 72.4% showed moderate positivity, and only 3.1% showed strong positivity for biofilm production. Most S. aureus strains showed moderate and strong biofilm production (93.8% and 4.2%, respectively); S. mutans had 86.6% of strains with moderate biofilm production and 1.2% with strong biofilm production, while other streptococci had less biofilm production capacity. The DMFT index for the Yemeni patients included in the study was 5.9±2.4; there was a higher mean±SD (6.2±1.9) of DMFT for weak biofilm-producing bacteria with a difference equal to 3.5, 95% CI=1.4-4.2 (p=0.0001); for moderate biofilm-producing bacteria (6.9±2.5, difference=3.5, 95% CI=1.8-5.2, p=0.0001); and for strong-producing biofilms (mean±SD=6.2±2.9, p=0.03). Conclusion: In conclusion, a higher DMFT was observed in biofilm producers than in non-biofilm producers. The prime biofilm producers were S. aureus, S. mutans, and E. coli. Peer Review History: Received 6 December 2023; Revised 30 January 2024; Accepted 26 February; Available online 15 March 2024 Academic Editor: Dr. Asia Selman Abdullah, Pharmacy institute, University of Basrah, Iraq, asia_abdullah65@yahoo.com Average Peer review marks at initial stage: 6.0/10 Average Peer review marks at publication stage: 7.0/10 Reviewers: Ahmad Najib, Universitas Muslim Indonesia, Makassar, Indonesia, ahmad.najib@umi.ac.id Dr. Mohsen Ali Al-Hamzi, Thamar University, Factuality of Dentistry, Yemen. mohsenalhamzi@gmail.com

The Effect of Aging on Artificial Saliva at Different pH Values on the Color Stability of New Generation Denture Base Materials.

New-generation denture base materials are used successfully in denture fabrication; however, the effect of saliva pH change on the color stability of materials is unknown. The purpose of this in vitro study is to evaluate the color stability of new-generation denture base materials after immersion in artificial saliva with different pH values (3,7,14). Disc-shaped samples (Ø 10 mm x 2 mm) were prepared from three different denture base materials (1 pre-polymerized polymethylmethacrylate [PMMA], 1 graphene-reinforced PMMA, and heat-cure polymethyl methacrylate resin) (n=10). After polishing, color coordinates were measured using a PCE-CSM 5 colorimeter programmed in the CIE system (L* a* b*). The samples were kept in artificial saliva at different pH values and 37°C for 21 days. At the end of 21 days, color coordinates were measured again. The suitability of the measurements for a normal distribution was examined with the Kolmogro-Smirnov test. Whether color measurements obtained at different pH levels differed according to groups was examined with the Kruskal-Wallis test. The correlation between the CIEDE2000 and CIELab color difference formulas was examined by correlation analysis. The highest color difference occurred in heat-cure samples at pH 3 (p<0.001). The color difference at different pH values was least observed in pre-polymerized PMMA samples. Significant color differences occurred in the graphene-reinforced pre-polymerized PMMA group at pH 7 (p<0.001). It was observed that color differences occurred in all groups. Dentures made of new-generation CAD/CAM PMMA, which are less exposed to color differences, can be recommended for elderly patients with systemic diseases who are frequently exposed to pH changes in the oral cavity. Color differences on denture surfaces over time negatively affect aesthetics. Since pH changes cause changes on the prosthesis surface, it may be recommended for these patients to fabricate dentures from new-generation CAD/CAM PMMA resins, which are less deformable.

The impact of femoral head size on the wear evolution at contacting surfaces of total hip prostheses: A finite element analysis

Total Hip Arthroplasty has been a revolutionary technique in restoring mobility to patients with damaged hip joints. The introduction of modular components of the hip prosthesis allowed for bespoke solutions based on the requirements of the patient. The femoral stem is designed with a conical trunnion to allow for assembly of different femoral head sizes based on surgical requirements. The femoral head diameters for a metal-on-polyethylene hip prosthesis have typically ranged between 22 mm and 36 mm and are typically manufactured using Cobalt–Chromium alloy. A smaller femoral head diameter is associated with lower wear of the polyethylene, however, there is a higher risk of dislocation. In this study, a finite element model of a standard commercial hip arthroplasty prosthesis was modelled with femoral head diameters ranging from 22 mm to 36 mm to investigate the wear evolution and material loss at both contacting surfaces (acetabular cup and femoral stem trunnion). The finite element model, coupled with a validated in-house wear algorithm modelled a human walking for 10 million steps. The results have shown that as the femoral head size increased, the amount of wear on all contacting surfaces increased. As the femoral head diameter increased from 22 mm to 36 mm, the highly cross-linked polyethylene (XLPE) volumetric wear increased by 61% from 98.6 mm3 to 159.5 mm3 while the femoral head taper surface volumetric wear increased by 21% from 4.18 mm3 to 4.95 mm3. This study has provided an insight into the amount of increased wear as the femoral head size increased which can highlight the life span of these prostheses in the human body.

Characterization of pathogenic microbiome on removable prostheses with different levels of cleanliness using 2bRAD-M metagenomic sequencing

ABSTRACT Background The microbiomes on the surface of unclean removable prostheses are complex and yet largely underexplored using metagenomic sequencing technology. Objectives To characterize the microbiome of removable prostheses with different levels of cleanliness using Type IIB Restriction-site Associated DNA for Microbiome (2bRAD-M) sequencing and compare the Microbial Index of Pathogenic Bacteria (MIP) between clean and unclean prostheses. Materials and Methods Ninety-seven removable prostheses were classified into ‘clean’ and ‘unclean’ groups. All prosthesis plaque samples underwent 2bRAD metagenomic sequencing to characterize the species-resolved microbial composition. MIPs for clean and unclean prostheses were calculated based on the sum of the relative abundance of pathogenic bacteria in a microbiome using a reference database that contains opportunistic pathogenic bacteria and disease-associated information. Results Beta diversity analyses based on Jaccard qualitative and Bray-Curtis quantitative distance matrices identified significant differences between the two groups (p < 0.05). There was a significant enrichment of many pathogenic bacteria in the unclean prosthesis group. The MIP for unclean prostheses (0.47 ± 0.25) was significantly higher than for clean prostheses (0.37 ± 0.29), p = 0.029. Conclusions The microbial community of plaque samples from ‘unclean’ prostheses demonstrated compositional differences compared with ‘clean’ prostheses. In addition, the pathogenic microbiome in the ‘unclean’ versus ‘clean’ group differed.

ОПТИМИЗАЦИЯ ЗАКЛЮЧИТЕЛЬНОГО ЭТАПА ПОДГОТОВКИ ЗУБНОГО ПРОТЕЗА НА ОСНОВЕ ДИОКСИДА ЦИРКОНИЯ К ФИКСАЦИИ ВО РТУ ПАЦИЕНТА

Laboratory study of the acid etching impact on the surface of domestic ceramic translucent zirconium dioxide-based samples by special acid composition has been conducted in order to improve the esthetic qualities of ceramic dentures based on zirconium dioxide as well as to reduce the risk of their breakage and debonding by improving the final treatment methods of the prosthesis surface before fixation in the oral cavity, namely special acid etching of the internal surface and fluorescent glaze applied only to the prosthesis areas visible at a wide smile. The adhesive strength to composite resin cement has been assessed and three different dental fluorescent glazes have been studied for bending strength of zirconium dioxide samples depending on the coating area. The issue of combined effect of the zirconium dioxide-based ceramic’s surface chemical preparation has been studied with a view to increasing both the adhesive strength and the esthetic characteristics. A conclusive reduction in the strength of zirconium dioxide-based ceramic samples after the ceramic coating of each of the studied fluorescent glazes and a significant increase in the adhesive strength of ceramic with composite resin cement after etching with a special composition are shown. To improve the esthetics of zirconium dioxide dental prostheses, prevent the fractures of prostheses and reduce the possibility of their debonding in the oral cavity, it is recommended to apply fluorescent glaze with a minimum sufficient thickness and only on the vestibular and partially occlusal zones, and before fixing to composite resin cement in the oral cavity it is advisable to carry out chemical treatment of the ceramics’ bonded surface with a special etching solution.

(128) Characterizing Antibiotic Susceptibility of the Penile Prosthesis Microbiome

Abstract Introduction Inflatable penile prostheses (IPP) are the gold standard treatment for erectile dysfunction refractory to conservative therapies. However, infection remains a significant concern and the presence of microbial biofilms on both infected and non-infected devices has recently been demonstrated. Various antimicrobials are used for prophylaxis intraoperatively and postoperatively. It remains unknown how these antimicrobials affect the growth of bacteria and their associated biofilms. We sought to assess how commonly used antimicrobials influenced growth of bacterial isolates previously isolated from both non-infected and infected devices, obtained during revisional surgery. Objective The goal of this study was to evaluate growth of bacterial isolates previously obtained from non-infected and infected IPPs. Isolates were exposed to single or multi-antibiotic combinations to assess degree of inhibition of bacterial growth. Methods In this IRB-approved study, 35 bacterial isolates had been previously obtained from patients who had been consented for IPP revision or replacement secondary to mechanical failure, pain, or device infection. Bacteria were plated on brain-heart-infusion (BHI) agar plates and allowed to incubate for 48 hours. Standard-sized antibiotic discs were introduced into the grown bacterial colonies consisting of the following single or multi-agent regimens: bacitracin, cefaclor, cephazolin, gentamicin, levofloxacin, trimethoprim-sulfamethoxazole, tobramycin, vancomycin, piperacillin/tazobactam, gentamicin + piperacillin/tazobactam, gentamicin + cephazolin, and gentamicin + vancomycin. Zones of inhibition (ZOI) were measured after placement of the antibiotic discs in the bacterial colonies. Statistics were analyzed with false discovery rate corrected, one-sample t-tests. Quantification of antibiotic resistance was defined as follows: Resistant: ZOI not significantly different from 0 in one sample t-test Susceptible: ZOI significantly greater than 0, but mean is &amp;lt;10mm Highly susceptible: ZOI significantly greater than 0, but mean is 10-20mm Exceptionally susceptible: ZOI significantly greater than 0, but mean is &amp;gt;20mm Taxonomic classification of bacterial isolates was provided by extracting DNA from pure cultures and sequencing the full length 16S rRNA gene using Sanger sequencing, after amplification with two different primer sets to provide overlapping sequence regions. Results Of the antibiotics tested, TMP-SMX was found to have the highest percentage of resistant isolates (54.3%) of the 35 tested, with bacitracin having the second most (40%). Both tobramycin and TMP-SMX had 0.0% of isolates be exceptionally susceptible. Combination piperacillin/tazobactam was found to have the highest percentage of exceptionally susceptible isolates (11.4%). A large majority of isolates were highly susceptible to gentamicin + piperacillin/tazobactam (91.4%), piperacillin/tazobactam (74.3%), gentamicin + cefazolin (74.3%), and levofloxacin (88.6%), while greater than half of isolates were highly susceptible to cefazolin (62.9%) and cefaclor (54.3%)." Conclusions Our results demonstrate that cefaclor or bacitracin prevented growth of bacterial isolates obtained from IPPs explanted for mechanical failure, pain or infection. Further investigation is needed to characterize how intraoperative and postoperative antibiotic influences a symbiotic or dysbiotic community of microbes on the surface of penile prostheses. By better understanding the interactions between microbes, antibiotics and host, novel therapeutics might promote a non-infected, symbiotic microenvironment. Disclosure Yes, this is sponsored by industry/sponsor: Coloplast corporation. Clarification: Industry funding only - investigator initiated and executed study. Any of the authors act as a consultant, employee or shareholder of an industry for: Coloplast, boston scientific.

Accuracy of Occlusal Contacts of All-Ceramic Single Crowns Designed by Virtual Articulators from a CAD/CAM System: A Preliminary Evaluation.

To compare the static and dynamic occlusion of all-ceramic single crowns designed by mechanical and virtual articulators, by evalua6ng the accuracy of occlusal contacts of prostheses designed by virtual articulators and the feasibility of clinical application of CAD/CAM virtual articulators. Nine subjects with an average age of 27 years who needed crown repair were recruited. After preparation of the all-ceramic crowns, two zirconia crowns were designed and fabricated through digital procedures and traditional methods. The intraoral scanner, Geomagic software, and T-Scan analyzer were used to analyze the occlusal contact points, areas, and the occlusal force percentage peak before the treatment and after the two crowns were temporarily fixed. There was a significant difference in the number of occlusal contact points and areas between the mechanical group and control group (preoperation group), but there was no obvious difference between the virtual group and control group. The occlusal contact overlapping areas of the virtual-control group were significantly larger than those of the mechanical-control group. The occlusal force percentage peak of the tested teeth was slightly larger in the mechanical group than in the virtual group. The posterior single crown designed by a virtual articulator restored the intercuspal occlusal better than one designed by a mechanical articulator, and it produced less dynamic occlusal interference. This finding suggests that virtual articulators can provide guidance for the design and adjustment of the occlusal surface of posterior single crown prostheses.

Giant Dental Calculus Mimicking a Tumor: A Case Report

Dental calculus consists of mineralized bacterial plaque that forms on the surfaces of natural teeth and dental prostheses. Giant dental calculus mimicking a tumor is an unusual presentation. Buccal surfaces of the maxillary molars and the lingual surfaces of the mandibular anterior teeth are the most common location for calculus deposition. This case report presents a case of giant dental calculus mimicking a tumor on the labial surface of the mandible and its diagnostic dilemma, treatment and role of proper oral hygiene measures.

Biofilm accumulation on complete arch subperiosteal implant-supported prostheses: Effect of pontic type

Statement of problemComplete arch subperiosteal implant-supported prostheses present challenges in terms of effective cleaning, leading to the accumulation of biofilm on their intaglio surfaces. The association between different intaglio surface morphologies and biofilm accumulation on complete arch subperiosteal implant-supported prostheses is unclear. PurposeThe purpose of this in vitro study was to investigate the correlation between the intaglio surface of complete arch subperiosteal implant-supported prostheses and biofilm accumulation. Material and methodsSixty-eight complete arch subperiosteal implant-supported prostheses were fabricated with varying interimplant distances and pontic morphologies. Four different types of pontic morphologies were included: saddle, flat, scalloped, and ovate. To simulate biofilm accumulation, a green aerosol was sprayed onto the intaglio surface. Dental floss was used to clean the colored spray from the intaglio surface. The intaglio surfaces of prostheses were then scanned with an intraoral scanner. The biofilm areas were identified and calculated by using a 3-dimensional macroscopical quantification method. The distances between adjacent implants and transmucosal height were measured. The correlation between interimplant distances and biofilm areas, and the correlation between the biofilm areas and transmucosal height, were analyzed using the Spearman test. Furthermore, a generalized estimating equation (GEE) was employed to examine the relationship between pontic morphology and biofilm area, adjusting for location, cantilever, implant distance, and transmucosal height (α=.05). ResultsA significant correlation was found between the biofilm area and transmucosal height (correlation coefficient=0.208, P<.001). A significant increase in biofilm accumulation was observed in the saddle group compared with the 3 groups in GEE Models I and II. ConclusionsFlat pontics and ovate pontics have significantly lower biofilm retention. Moreover, transmucosal height plays a significant role in biofilm accumulation in the pontic area.

On the Polymeric Coating Deposition Techniques to Increase Body Acceptance and Allow Drug Delivery in Smart Bio-devices

Currently, prosthetic devices have been significantly improved thanks to highly biocompatible metallic alloys, such as titanium alloys, and owing to the use of antibiotic treatments to allow higher acceptance of the implant. However, risks of infection or implants collapse are always possible since the human body recognizes prosthetic devices as foreign bodies and reacts to them accordingly. The surface of a prosthetic device guides the first interactions with the surrounding environment, and thus the necessity to act on the prosthesis surface with a local approach arises. Indeed, the creation of surface coatings that can potentially be loaded to perform local drug delivery represents a way to reduce systemic antibiotic delivery while improving body tolerance to the implanted devices. Within this framework, the current study aims to investigate the influence of different techniques applied to produce polymer-based coatings upon titanium alloy bio-devices, with the purpose of optimizing their durability. Specifically, the experimental campaign examined three different coating techniques (electrophoretic deposition, dip coating, and spray coating), to compare the results in terms of coating uniformity and mechanical adhesion to the titanium alloy.

Biomedical devices surface functionalization through superfinishing processes to improve tribocorrosion

Permanent prosthesis surface conditions play a key role on the implants overall mechanical performance. Furthermore, the increased number of arthroplasty surgery represents a reason for the necessity of higher quality standards for the biomedical devices. Employing and optimizing severe plastic deformation processes represents a way to obtain implants with higher performance, therefore this work aims, through the application of burnishing process, to combine innovative machining finishing operations coupled with environmentally friendly cooling lubricant techniques to improve the surface integrity and the tribocorrosion resistance of biomedical devices in order to increase their quality, durability and reliability. Another phenomenon taken into account is the tribological behavior that could generates an irreversible transformation of the materials and the release of particles and metal ions in toxic concentrations in the biological environment in which the devices are implanted. One of the most used materials for permanent prosthetic implants is the Ti6Al4V alloy but its tribological behavior is still challenging for the application. In this work Ti6Al4V bars have undergone machining with semi-finishing parameters and burnishing processes, then the effects of sole machining and its combination with burnishing on surface quality and specific wear rate (SWR) have been assessed with respect to as received surface conditions.

Impact of chitosan-incorporated toothpaste on roughness, gloss, and antifungal potential of acrylic resin

This study aimed to test the efficacy of different silica-based toothpastes with or without chitosan, as a method of cleaning the acrylic surfaces of denture prostheses. Acrylic resin specimens were prepared to evaluate surface roughness and gloss (n = 10), and Candida albicans adhesion/inhibition (n = 2). Two toothpastes with different degrees of abrasiveness were used: Colgate (CT) and Elmex (EX), with or without 0.5% chitosan (Ch) microparticles (CTCh or EXCh, respectively). The negative control was brushed with distilled water. Brushing was simulated with a machine. Surface roughness and gloss were analyzed before and after brushing. Candida albicans incidence/inhibition was tested qualitatively to determine the acrylic resin antifungal activity. The roughness and gloss data were analyzed with a generalized linear model, and the Kruskal Wallis and Dunn tests, respectively (α = 5%). Brushing with toothpastes increased roughness and reduced gloss, compared with the negative control (p < 0.05). CT showed a more significantly different change in roughness and gloss, in relation to the other groups (p < 0.05). Addition of chitosan to CT reduced its abrasive potential, and yielded results similar to those of EX and EXCh. Specimens brushed with CT showed a higher potential for Candida albicans adherence, despite its higher antifungal action. Addition of chitosan to the toothpaste made both toothpaste and brushing more effective in inhibiting Candida albicans. CT had the potential to increase roughness, reduce gloss, and increase Candida albicans adherence. In contrast, chitosan added to CT showed greater antifungal potential, and a higher synergistic effect than EX.

Intraoral low-temperature degradation of monolithic zirconia dental prostheses: 5-year results of a prospective clinical study with ex vivo monitoring

ObjectivesTo investigate the 5-year intraoral evolution and kinetics of low-temperature degradation (LTD) of second-generation monolithic prostheses made of 3% molar yttrium-doped tetragonal zirconia polycrystal (3Y-TZP) and the influence of masticatory mechanical stresses and glaze layer on this evolution. MethodsA total of 101 posterior tooth elements were included in this prospective clinical study, which comprised ex vivo LTD monitoring (at baseline, 6 months, 1 year, 2 years, 3 years, and 5 years) using Raman spectroscopy (n = 2640 monoclinic phase measurement points per evaluation time) and scanning electron microscopy (SEM). Four types of areas (1–2 mm2 surface, six on molars, and four on premolars) were analysed on each element surface: occlusal, axial, glazed, or unglazed. Raman mapping, high-resolution SEM, and focused ion beam-SEM were performed on selected samples. ResultsThe dental prostheses developed a tetragonal-to-monoclinic transformation at the extreme surface of the material after six months in a buccal environment, and this process increased significantly over time. Over the five years of monitoring, the transformation developed nonuniformly with the presence of localised clusters of monoclinic grains. Tribological stresses generate grain pull-out from these clusters, which may raise questions regarding the release of 3Y-TZP nanoparticles into the body. The prosthesis fracture rate was 4.5% after 5 years. SignificanceLTD developed in vivo on the surfaces of 3Y-TZP dental prostheses and progressed slowly but significantly over time, up to 5 years investigation. However, the effects of aging on the failure rate recorded and of zirconia nanoparticles released into the body require further investigation.

Reverse scan body: The scan pattern affects the fit of complete-arch prototype prostheses.

To assess the effect of different scan patterns on the fit of implant-supported complete-arch prototype prostheses fabricated via a complete digital extraoral protocol with a reverse scan body. A mandibular cast with four multi-unit abutment (MUA) implant analogs with adequate antero-posterior spread served as the reference cast, simulating a common clinical patient situation, and a polymethylmethacrylate interim screw-retained prosthesis was fabricated on it. Novel reverse scan bodies were connected to the interim prosthesis on the intaglio of the MUA abutments and extraoral scanning was performed with a white light intraoral scanner (TRIOS 4; 3 shape) and three different scan patterns: starting from the occlusal surface of the interim prosthesis (O-group), starting from the intaglio (I-group), and helix pattern (H-group). The resulting STL files from the three groups were then imported to computer-aided design (CAD) software and after the digital design, the STL files were exported to a computer-aided manufacturing (CAM) milling machine which generated a total of 15 CAD-CAM milled prototype prostheses per group. Two clinicians assessed the fit of each digitally fabricated prototype prosthesis on the reference cast, utilizing the screw-resistance test and radiographic evaluation. Fisher's exact test was used to test the difference between the three groups, and Cohen's k-score was used to assess the inter-examiner agreement. Out of the three different groups, the O-group scan pattern led to 100% prosthesis fit, while the prototype prostheses generated from I- and H-groups had 80% and 53% fit, respectively. The results were statistically significant (p = 0.008). Occlusal scan pattern leads to fitting milled prototype prostheses after extraoral scanning with reverse scan bodies without intraoral implant data acquisition.