Bi-antibiotic-impregnated bone cements (BIBCs) are widely used in orthopaedics as a prophylactic agent (depot) to address post-surgical infections. Although hardness is widely considered a viable index to measure the integrity of the cement structure, there are few specific studies involving changes in hardness characteristics of BIBCs post elution of high doses of two widely used antibiotics: tobramycin and gentamicin. Increased doses of antibiotics and increased duration of elution may also decrease the hardness of polymethyl methacrylate (PMMA) bone cement, thus increasing the chances of shattering, scratching, and deformation.In this project, we have investigated the changes in surface hardness of five different antibiotic-loaded specimens: 0.5 g tobramycin and 0.5 g gentamicin together, 1 g tobramycin, 1 g gentamicin, 5 g tobramycin and 5 g gentamicin together, and 10 g tobramycin (each added to 40 g of PMMA), post elution for various time periods (1, 3, and 21 days). The effect of hydration on the hardness of bone cement was studied to replicate in vivo conditions. The micro-indentation tester (Buehler m5103) was utilized to determine if the increased antibiotic loads would compromise the integrity of the bone cement matrix.The results demonstrated that the amount of drug initially incorporated determined the hardness of the cement post elution. As compared to the control (no antibiotic), specimens containing 1 and 10 g of antibiotic exhibited over 50% and 73% decrease in hardness, respectively. The different treatment durations (post 1 day) as well as the hydration conditions had insignificant effect on the hardness of the cement.

Background: This study aimed to assess the effects of methyl ethyl ketone (MEK) and ethyl acetate (EA) on dentin Microhardness, used as resin sealer solvents. Methods: Eighty halves of single-rooted teeth were randomly divided into four groups to apply MEK, EA, chloroform, or saline solution. Vickers hardness values were measured for three root levels before and after the direct application of solvents for 5 and 15 minutes or a 1-minute application with ultrasonic agitation. The results were analyzed using repeated-measures ANOVA, and adjustments were made for comparisons with Bonferroni tests. Results: The dentin Microhardness decreased in all the solvent groups (P < 0. 05). The changes in Microhardness increased with prolonged exposure times, except for the saline solution group. Chloroform exhibited the most significant decrease in value. Furthermore, ultrasonic agitation elicited a more substantial decline in values. Conclusion: MEK and EA might be preferred over chloroform as a solvent for resin sealers because they offer an attenuated decrease in dentin Microhardness and do not have guttapercha-dissolving properties.

Objectives This study aimed to synthesize an herbal remineralizing paste containing the extracts of Miswak, licorice, aloe vera, propolis, and honey and compare its effect with 5% sodium fluoride (NaF) and 1. 23% acidulated phosphate fluoride (APF) on demineralized enamel Microhardness. Methods This experimental study was conducted on 72 extracted sound premolars. After obtaining the extracts and synthesis of the herbal paste, the baseline Microhardness was measured, and the samples underwent a 14-day pH cycling. Next, the teeth were randomly assigned to six groups (N=12) for application of (I) 5% NaF for one minute, (II) 1. 23% APF for one minute, (III) herbal paste for one minute, (IV) herbal paste for five minutes, (V) herbal paste for 15 minutes, and (VI) herbal paste for six hours. The Microhardness was measured again. Data were analyzed by one-way analysis of variance (ANOVA) (alpha=0. 05). Results The mean final Microhardness was significantly higher than the primary Microhardness in all groups (P<0. 05). The highest Microhardness was noted in group IV, followed by II, VI, I, V and III. One-way ANOVA revealed no significant difference between the final Microhardness of study groups (P=0. 97). Conclusion The effect of synthesized herbal paste on demineralized enamel Microhardness was comparable to that of 5% NaF and 1. 23% APF. Due to the lack of a significant difference in duration of application, this paste may be applied for one minute to benefit from its remineralizing effects.