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Background@#Nicotine can have detrimental effects on dental implant osseointegration. This study aimed to evaluate the influence of systemic L-arginine supplement on the osseointegration of dental implants in nicotine consumer dogs. @*Methods@#Twelve 1-year Labrador Retriever dogs had their right and left third and fourth mandibular premolars removed, and the sockets were left to heal for 6 months. Dogs were randomly divided into three groups (n = 16): group 1—0.2 mg/kg nicotine was injected twice daily; group 2—0.2 mg/kg nicotine was injected twice daily in addition to 200 mg/kg L-arginine capsules taken orally; and group 3—placebo. Forty-eight dental implants were inserted into the healed sockets of the dog’s mandible and were assessed by implant stability quotient (ISQ) using resonance frequency analysis (RFA) during 4 weeks and insertion and removal torque value analysis. @*Results@#No implant failure occurred during the study period. The change in torque value between insertion and removal was similar in the placebo and nicotine+arginine consumer dogs (p = 0.276), which shows a positive effect of arginine supplementation in nicotine consumers. There was a significant difference in torque value change between nicotine+arginine vs. nicotine consumers (p = 0.049) and placebo vs. nicotine (p = 0.003). After 4 weeks, the placebo had the most significant improvement in torque value (47.0 ± 16.9), followed by nicotine+arginine (25.1 ± 37.8), and the worst torque value was for the nicotine group (− 5.7 ± 24.0) pound per inch. The results show that except in the first week, there are significant differences in ISQ between the groups in different periods. ISQ in all of the groups has reduced at first but then increased over time. At the time of implant placement, insertion torque was significantly higher in the nicotine consumer group than the nicotine+arginine consumer group and placebo group (p = 0.020). @*Conclusion@#Arginine supplementation promotes bone healing and implant primary stability by improving dental implant osseointegration biomechanical characteristics.
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PURPOSE: Impact forces in implant supported FDP (fixed dental prosthesis) are higher than that of tooth supported FDPs and the compositions used in frameworks also has a paramount role for biomechanical reasons. The aim of this study was to evaluate the flexural strength of two different zirconia frameworks. MATERIALS AND METHODS: Two implant abutments with 3.8 mm and 4.5 mm platform were used as premolar and molar. They were mounted vertically in an acrylic resin block. A model with steel retainers and removable abutments was fabricated by milling machine; and 10 FDP frameworks were fabricated for each Biodenta and Cercon systems. All samples were thermo-cycled for 2000 times in 5-55degrees C temperature and embedded in 37degrees C artificial saliva for one week. The flexural test was done by a rod with 2 mm ending diameter which was applied to the multi-electromechanical machine. The force was inserted until observing fracture. The collected data were analyzed with SPSS software ver.15, using Weibull modulus and independent t-test with the level of significance at alpha=.05. RESULTS: The mean load bearing capacity values were higher in Biodenta but with no significant differences (P>.05). The Biodenta frameworks showed higher load bearing capacity (F0=1700) than Cercon frameworks (F0=1520) but the reliability (m) was higher in Cercon (m=7.5). CONCLUSION: There was no significant difference between flexural strengths of both zirconia based framework systems; and both Biodenta and Cercon systems are capable to withstand biting force (even parafunctions) in posterior implant-supported bridges with no significant differences.
Subject(s)
Bicuspid , Molar , Saliva, Artificial , Steel , Tooth , Weight-BearingABSTRACT
The cytotoxicity of the biomaterials is a key issue that should be addressed prior to pre-clinical applications. This study was designed to evaluate and compare the cytotoxixity of two forms of bioactive glasses:nanopowder: and micropowder. Human HGF1-PI53 gingival fibroblast cells were used to evaluate the cytotoxicity of 0.5, 1, 1.5, 2, 5, 10, 15 and 20 mg/mL concentrations of the two bioactive glasses via MTT assay. The results were statistically analyzed using analysis of variance and Tukey's test. A p-value less than 0.05 was considered statistically significant. Results showed that two bioactive glasses hadstatistically significant differences at 5, 10, 15 and 20 mg/mL concentrations [p-value < 0.05] and there was no correlation between time and cell cytotoxicity of bioactive glasses [p-value > 0.05], using t-test and Spearman's correlation coefficient. We conclude that that cytotoxicity of nanopowder bioactive glass at concentrations /= 5 mg/mL in the first 48 h of applications
Subject(s)
Biocompatible Materials , Fibroblasts , Toxicity Tests , Nanoparticles , Tissue EngineeringABSTRACT
Mean bar failure in overdenture-supported implant has been reported to be 3.97 percent; even this low failure rate is unacceptable for patients because of its cost compared with complete denture. The aim of this study was to assess stress distribution in different points of the bar of overdenture-supported implants by finite elements analysis. In this descriptive study, stress distribution on the bar of mandibular overdenture was evaluated by the finite elements analysis [FEA]. Implants in two canine areas were connected to each other by one bar at the distance of 2 mm from the lining tissue of the edentulous ridge. Then the vertical force applied to the left first molar increased gradually from 0.5 to 50 N and stress distributions were recorded at different points of the bar. By increasing the force up to 6.06 N, stress was uniformly distributed over the bar, but with greater force stress was focused on the border of the middle third and the force application third. This pattern of stress distribution continued parallel with an increase in the force. Failure is higher at the border area between the middle third of the bar and the third near the applied force due to maximum stress; therefore, reinforcement of the bar at this area is suggested
ABSTRACT
PURPOSE: Veneering porcelain might be delaminated from underlying zirconia-based ceramics. The aim of this study was the evaluation of the effect of different surface treatments and type of zirconia (white or colored) on shear bond strength (SBS) of zirconia core and its veneering porcelain. MATERIALS AND METHODS: Eighty zirconia disks (40 white and 40 colored; 10 mm in diameter and 4 mm thick) were treated with three different mechanical surface conditioning methods (Sandblasting with 110 microm Al2O3 particle, grinding, sandblasting and liner application). One group had received no treatment. These disks were veneered with 3 mm thick and 5 mm diameter Cercon Ceram Kiss porcelain and SBS test was conducted (cross-head speed = 1 mm/min). Two and one way ANOVA, Tukey's HSD Past hoc, and T-test were selected to analyzed the data (alpha=0.05). RESULTS: In this study, the factor of different types of zirconia ceramics (P=.462) had no significant effect on SBS, but the factors of different surface modification techniques (P=.005) and interaction effect (P=.018) had a significant effect on SBS. Within colored zirconia group, there were no significant differences in mean SBS among the four surface treatment subgroups (P=0.183). Within white zirconia group, "Ground group" exhibited a significantly lower SBS value than "as milled" or control (P=0.001) and liner (P=.05) groups. CONCLUSION: Type of zirconia did not have any effect on bond strength between zirconia core and veneer ceramic. Surface treatment had different effects on the SBS of the different zirconia types and grinding dramatically decreased the SBS of white zirconia-porcelain.