Saudi Cultural Missions Theses & Dissertations
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Item Restricted The Effect of Er:YAG Laser Treatment on Biofilm Formation on Titanium and Zirconia Disc Surfaces(Journal of Periodontology, 2023) Assery, Nasser; Tsigarida, AlexandraBackground: Lasers represent a promising method for implant decontamination, but evidence on implant surface changes and subsequent biofilm formation is limited. This study aimed to assess the effect of Er:YAG laser treatment on zirconia and titanium discs, and the differences in biofilm formation as a result of surface alterations. Methods: A two-stage (in vitro and in vivo) experiment utilizing Er:YAG laser on titanium and zirconia discs was performed. In vitro, surface alterations, roughness, and elemental-material weight differences following laser treatment were assessed using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). In vivo, four participants wore custom-made intra-oral stents, embedded with laser-treated and untreated titanium and zirconia discs overnight. Biofilm-coated discs were stained using nucleic acid fluorescence dye and visualized using multiphoton confocal laser scanning microscopy. Biofilm 3D structure, biomass, thickness, and live-to-dead bacteria ratio were assessed. Results: Both titanium (TiZir) and zirconia (YTZP) discs treated with Er:YAG laser resulted in visual surface alterations, but showed no significant change in average surface roughness (titanium P=0.53, zirconia P=0.34) or elemental-material-weight (TiZir, P=0.98), (YTZP, P=0.96). No significant differences on biofilm biomass, average thickness and live-to-dead bacteria ratio of laser-treated titanium and zirconia discs, were identified compared to untreated groups (titanium P > 0.05, zirconia P >0.05). Generally, zirconia discs presented with a lower live-to-dead bacteria ratio compared to titanium discs, regardless of laser treatment. Conclusion: Er:YAG laser treatment of titanium and zirconia implant surfaces does not significantly affect surface roughness, elemental–material weight, and early biofilm formation in the oral cavity.26 0Item Restricted EVALUATION OF WELDED AND POLISHED STAINLESS-STEEL SURFACES IN SUPPORTING SPOREFORMER BIOFILMS IN DAIRY PLANTS(Saudi Digital Library, 2023-08-09) Almalki, Taghreed; Anand, SanjeevSpore-forming bacteria pose a significant challenge to the dairy industry, impacting the quality of dairy products. Bacillus species, in particular, contribute to spoilage of dairy items. Biofilm growth on stainless steel surfaces exacerbates biofouling, becoming reservoirs for persistent contamination and complicating removal due to their extracellular polysaccharide (EPS) matrix facilitating bacterial attachment. The first two studies aimed to assess biofilm growth on domestic and overseas stainless steel 316 and 304 surfaces using Geobacillus stearothermophilus (ATCC 15952), Bacillus licheniformis (ATCC 6634), Bacillus sporothermodurans (DSM 10599), and Bacillus coagulans (ATCC 5856). Among bacteria tested on domestic native 316 surfaces Geobacillus stearothermophilus and Bacillus sporothermodurans showed the least biofilm count, 4.03 and 4.05, respectively. Conversely, welded surfaces presented the highest biofilm formation for, B. licheniformis, B. coagulans, B. sporothermodurans, and G. stearothermophilus (4.86, 4.78, 4.79, and 4.73 log counts, respectively. The mean log counts across native, welded, and polished surfaces significantly differed for the four organisms (P<0.05), suggesting that polishing of weldments helps in reducing the biofilm formation. Among the findings, B. sporothermodurans exhibited minimal biofilm formation on SS 304 native surfaces with a log count of 3.87, followed by 4.04 on polished surfaces. Welded surfaces displayed the highest biofilm growth among all surface types tested, while polished surfaces exhibited lower biofilm formation compared to welded surfaces." Overall, for native, welded, and polished surfaces, the average log counts were significantly different for the four organisms (P<0.05) tested. The results indicate that polishing of weldments helps in reducing biofilm formation. For the overseas coupons, the result indicated that all bacteria tested showed a similar biofilm growth on SS316 native surfaces. However, on polished SS 316 surfaces, G. stearothermophilus demonstrated the highest biofilm growth, followed by B. licheniformis, while B. coagulans and B. sporothermodurans had similar biofilm counts. On welded SS 316 surfaces, G. stearothermophilus exhibited the highest biofilm formation, followed by B. licheniformis and B. sporothermodurans, while B. coagulans showed the least biofilm formation. The highest observed biofilm formation among the tested bacteria on SS 304 native surfaces was for B. coagulans at 5.97 logs, followed by B. licheniformis 5.4 logs. Bacillus coagulans showed more biofilm formation on SS 304 polished surfaces among the four bacteria tested. Overall, for native, welded, and polished surfaces, the average log counts were significantly different for the four organisms (P<0.05) tested. The results indicate that polishing of weldments helps in reducing biofilm formation. These studies demonstrated that SS 304 exhibited higher biofilm formation compared to SS 316 in both domestic and overseas coupon samples. Based on the anticipated result it is likely to find higher biofilm in 304 more than 316 SS surfaces. The third study was conducted to evaluate the SS surfaces roughness changes after applying CIP chemical solution for 10 consecutive cycles following 3 CIP protocols. The result indicated that the surface roughness had a slight change after the fifth cycle, while the greatest change happened after the 10th cycle. Applying frequent CIP to stainless steel could increase the roughness which supports biofilm formation. The last study was to evaluate the effect of CIP chemical solution on elastomer material such as EPDM, Teflon, Silicon, and Viton gaskets. The results showed that the surface roughness of all gasket types slightly increased after the first CIP cycle compared to pre-CIP measurements. However, the surface roughness measurements increased over time, as shown by the measurements after the third and fifth CIP cycles. This escalating surface roughness phenomenon precipitated an associated elevation in biofilm formation, thereby influencing the overall product quality.22 0