RECENT FINDINGS: Studies on the application of green and blue infrastructures in UHI mitigation are still scant in Asia. Their cooling performance is greatly influenced by their types, size, geometry, surface roughness, spread (threshold distance), temporal scales, topography, pollution levels, prevailing climate, and assessment techniques. Distinct urban characteristics, climatic conditions, environmental risks, lack of awareness and expertise, lack of policy and government incentives, and limited scientific studies are the major challenges in their implementation of UHI mitigation in Asia. Although green and blue infrastructures are associated with urban cooling, more in-depth experimental work and multidisciplinary research collaboration are paramount to exploring its implementation potential in Asia and other countries that share similar urban and environmental characteristics.
METHODS: To verify this hypothesis, a computational model was developed to simulate the thermochemical processes involved during TCA with sequential injection. Four major processes that take place during TCA were considered, i.e., the flow of acid and base, their neutralisation, the release of exothermic heat and the formation of thermal damage inside the tissue. Equimolar acid and base at 7.5 M was injected into the tissue intermittently. Six injection intervals, namely 3, 6, 15, 20, 30 and 60 s were investigated.
RESULTS: Shortening of the injection interval led to the enlargement of coagulation volume. If one considers only the coagulation volume as the determining factor, then a 15 s injection interval was found to be optimum. Conversely, if one places priority on safety, then a 3 s injection interval would result in the lowest amount of reagent residue inside the tissue after treatment. With a 3 s injection interval, the coagulation volume was found to be larger than that of simultaneous injection with the same treatment parameters. Not only that, the volume also surpassed that of radiofrequency ablation (RFA); a conventional thermal ablation technique commonly used for liver cancer treatment.
CONCLUSION: The numerical results verified the hypothesis that shortening the injection interval will lead to the formation of larger thermal coagulation zone during TCA with sequential injection. More importantly, a 3 s injection interval was found to be optimum for both efficacy (large coagulation volume) and safety (least amount of reagent residue).
MATERIALS AND METHODS: Using a stainless-steel mold, disc-shaped wax patterns with dimensions of 10 mm in diameter and 2 mm thick (in accordance with ADA Specification No. 12) were created and prepared for a total of 75 acrylic samples. Dimensions of all 75 acrylic samples were checked with a digital Vernier caliper. About 25 samples of denture base material were immersed in three different chemical disinfectants: Group I: immersed in chlorhexidine gluconate solution, group II: immersed in sodium hypochlorite solution, and group III: immersed in glutaraldehyde solution. All samples were scrubbed daily for 1 minute with the appropriate disinfectant and submerged for 10 minutes in the same disinfectant. Between disinfection cycles, samples were kept in distilled water at 37°C. Color stability was measured using a reflection spectrophotometer. Surface roughness values were measured by a profilometer at baseline following 15 days and 30 days.
RESULTS: After 15 days, the color stability was better in chlorhexidine gluconate solution group (4.88 ± 0.24) than sodium hypochlorite solution (4.74 ± 0.18) and glutaraldehyde solution group (4.46 ± 0.16). The mean surface roughness was less in glutaraldehyde solution group (2.10 ± 0.19), followed by chlorhexidine gluconate solution group (2.48 ± 0.09) and sodium hypochlorite solution group (2.64 ± 0.03). After 30 days, the color stability was significantly better in chlorhexidine gluconate solution group (4.40 ± 0.02), followed by sodium hypochlorite solution (4.06 ± 0.16) and glutaraldehyde solution group (3.87 ± 0.17). The mean surface roughness was significantly lesser in glutaraldehyde solution group (2.41 ± 0.14), followed by chlorhexidine gluconate solution group (2.94 ± 0.08) and sodium hypochlorite solution group (3.02 ± 0.13).
CONCLUSION: In conclusion, the color stability was significantly better in chlorhexidine gluconate solution group than sodium hypochlorite solution and glutaraldehyde solution group. But the surface roughness was significantly lesser in the glutaraldehyde solution group, followed by the chlorhexidine gluconate and sodium hypochlorite solution group.
CLINICAL SIGNIFICANCE: The maintenance of the prosthesis requires the use of a denture disinfectant; therefore, it is crucial to select one that is effective but would not have a negative impact on the denture base resin's inherent characteristics over time. How to cite this article: Kannaiyan K, Rakshit P, Bhat MPS, et al. Effect of Different Disinfecting Agents on Surface Roughness and Color Stability of Heat-cure Acrylic Denture Material: An In Vitro Study. J Contemp Dent Pract 2023;24(11):891-894.
PURPOSE: The purpose of this in vitro study was to compare the adherence of Streptococcus spp. and Candida spp. on 3D-printed denture bases prepared at different build orientations with conventional heat-polymerized resin.
MATERIAL AND METHODS: Resin specimens (n=5) with standardized 28.3 mm2 surface area were 3D printed at 0 and 60 degrees, and heat-polymerized (3DP-0, 3DP-60, and HP, respectively). The specimens were placed in a Nordini artificial mouth (NAM) model and exposed to 2 mL of clarified whole saliva to create a pellicle-coated substratum. Suspensions of Streptococcus mitis and Streptococcus sanguinis, Candida albicans and Candida glabrata, and a mixed species, each at 108 cfu/mL were pumped separately into the model for 24 hours to promote microbial adhesion. The resin specimens were then removed, placed in fresh media, and sonicated to dislodge attached microbes. Each suspension (100 μL) was aliquoted and spread on agar plates for colony counting. The resin specimens were also examined under a scanning electron microscope. The interaction between types of specimen and groups of microbes was examined with 2-way ANOVA and then further analysis with Tukey honest significant test and Kruskal-Wallis post hoc tests (α=.05).
RESULTS: A significant interaction was observed between the 3DP-0, 3DP-60, and HP specimen types and the groups of microbes adhering to the corresponding denture resin specimens (P
METHODS: Thermomechanical damage-maximum bone temperature, osteonecrosis diameter, osteonecrosis depth, maximum thrust force, and torque-were calculated using the finite element method under various margin heights (0.05-0.25 mm) and widths (0.02-0.26 mm). The simulation results were validated with experimental tests and previous research data.
RESULTS: The effect of margin height in increasing the maximum bone temperature, osteonecrosis diameter, and depth were at least 19.1%, 41.9%, and 59.6%, respectively. The thrust force and torque are highly sensitive to margin height. A higher margin height (0.21-0.25 mm) reduced the thrust force by 54.0% but increased drilling torque by 142.2%. The bone temperature, osteonecrosis diameter, and depth were 16.5%, 56.5%, and 81.4% lower, respectively, with increasing margin width. The minimum thrust force (11.1 N) and torque (41.9 Nmm) were produced with the highest margin width (0.26 mm). The margin height of 0.05-0.13 mm and a margin width of 0.22-0.26 produced the highest sum of weightage.
CONCLUSIONS: A surgical drill bit with a margin height of 0.05-0.13 mm and a margin width of 0.22-0.26 mm can produce minimum thermomechanical damage in cortical bone drilling. The insights regarding the suitable ranges for margin height and width from this study could be adopted in future research devoted to optimizing the margin of the existing surgical drill bit.