ABSTRACT
Heat polymerized denture base resins are a popular choice in prosthodontics for fabrication of partial or complete dentures, cranioplasts, hybrid implant prosthesis, and maxillofacial prosthetics. The wide utility of these materials can be attributed to their favourable mechanical properties. Despite the popularity gained by them, clinicians often encounter suboptimal flexural strength resulting in frequent fracture of the fabricated prosthesis. The purpose of this study was to compare the flexural strength (FS) of Polymethylmethacrylate (PMMA) modified using micro-additions of Multi-Walled Carbon Nanotubes (MWCNT) and Graphene Oxide (GO) as fillers respectively with PMMA having no micro-additions.METHODSThis is an in-vitro comparative study. Sixty samples of PMMA were divided in three groups of 20 each containing: Group 1: no micro additions (control group), Group 2: 0.5 wt% MWCNT in monomer of PMMA resin, Group 3: 0.5 wt% GO in monomer of PMMA resin. MWCNT and Graphene oxide were dispersed in Methylmethacrylate (monomer) respectively by ultrasonic agitation. Monomer and polymer were mixed in the ratio of 1:3. The samples were heat polymerised. Finished samples were subjected to 3-point bending test for checking their flexural strength. The results were statistically compared using one-way ANOVA followed by post hoc Bonferroni corrected paired T test for inter-group comparisons.RESULTSThe highest mean Flexural Strength of 36.5 MPa was recorded in Group 2 (MWCNT) followed by 31.55 MPa in Group 1 (control) and the least 29.72 MPa in Group 3 (Graphene Oxide) respectively. Intergroup comparisons revealed significant difference between Group 1 (control) & Group 2 (MWCNT) with “p=0.011” and between Group 2 (MWCNT) & Group 3 (Graphene Oxide) with “p<0.001”. However, no significant difference was found between Group 1 (control) and Group 3 (Graphene Oxide) with “p= 0.803”.CONCLUSIONSThe addition of 0.5 wt% MWCNT to PMMA is an easy, effective and economical step towards increasing the flexural strength and thus, decreasing the incidence of prosthesis fracture, when compared to 0.5 wt% graphene oxide or no micro additions.
ABSTRACT
Long-term retention of the restoration depends on strength and durability of the bond of the luting composite resin to the tooth and the porcelain substrates. Aims: This in vitro study was conducted to compare and evaluate the influence of hydrofluoric acid (HF) and acidulate phosphate fluoride (APF) gel-etched treatments on surface roughness and bond strength to dentin of a commercially available lithium disilicate ceramic (E-Max). Subjects and Methods: Sixty lithium disilicate ceramic disks measuring 5 mm in diameter and 2 mm thick were fabricated and divided into three groups: Group A (n = 24), Group B (n = 24), and Group C (n = 12) and were subdivided to Group A1, A2, and A3which were surface treated with 1.23% APF gel (pH = 3–4) at different time intervals 4, 7, and 10 min, respectively. Group B1, B2, and B3 were surface treated with 1% APF gel (pH = 1–2) at different time intervals 4, 7, and 10 min, respectively. Group C were surface treated with 9.6% HF (pH = 1–2) for 1 min. Morphological changes obtained with the surface treatments were analyzed using a surface profilometer. Statistical Analysis: All specimens were subjected to a tensile bond strength test using a tensometer, and the obtained data were statistically analyzed using Kruskal–Wallis test. Results: The surface roughness (μm) and bond strength (MPa) of lithium disilicate discs (samples) etched with 1.23% APF gel and 1% APF gel for 10 min and etched with 9.6% HF for 1 min showed no statistical significant difference among them. Conclusions: In this study, the lithium disilicate discs etched with 1.23% APF gel and 1% APF gel for 10 min showed similar surface roughness and bond strength to those etched with 9.6% HF for a minute.
ABSTRACT
Aims: The aim of the study is to find whether there is any relationship between glycated hemoglobin level and serum lipid profile in type 2 diabetes mellitus patients. Study Design: A total of 128 study participants were approached during a period 6 months of which 72 were confirmed cases of type-2 diabetes mellitus and remaining 56 were non- diabetic, and served as control subjects under the age group of 30-60 years. Methodology: Fasting blood samples were collected from all the subjects. Body Mass index (BMI) was calculated. Fasting plasma glucose, glycated hemoglobin (HbA1c) Total cholesterol (TC), triglyceride (TG) and High Density Lipoprotein (HDL) was measured using commercially available kits. Statistical analysis was performed by use o f SPSS version l6. Results: Plasma FBS level of diabetic group was significantly higher (p=0.001) than that of the non diabetic subjects as shown in table. TC, TG, LDL and VLDL were higher in diabetic group when compared to that of non-diabetic group, except for HDL which was lower in dian=betic group when compared to non-diabetic greoup. LDL was statistically significant between the non-diabetic and diabetic groups. HbA1c levels of both diabetic and non- diabetic groups showed a significant correlation with TG, HDL, LDL and VLDL (p<0.05) except for cholesterol. Conclusion: The findings of this study clearly indicate that HbA1c as a useful biomarker for long-term glycaemic control and also as a good predictor of lipid profile.
ABSTRACT
Aim: The aim of this study is to investigate whether dental nanocomposite Filtek Z350 XT and Ceram X-duo can benefit from electron beam irradiation in order to achieve increased flexural strength Place and Duration of Study: Department of Conservative Dentistry and Endodontics, A. B. Shetty Memorial Institute of Dental Sciences, Nitte University, Deralakatte, Mangalore, India and Microtron Centre; Department of Physics Mangalore University; Mangalore, India between May 2011 to March 2014. Materials and Methods: Materials were prepared on rectangular bar shaped specimens of 25-×2-×2-mm according to ISO standard -4049. Electron beam irradiation dose selected for the study were 1KGy, 3KGy and 5KGy. In total, 48 specimens were fabricated and divided into 4 groups based on radiation dose group I (non-radiated), group II (1KGy), group III (3KGy), group IV (5KGy) with 12 specimens in each. After 24 hours, specimens were subjected to 3-point bend test on a universal uniaxial servo mechanical testing machine. Statistical Analysis: Performed using one way ANOVA and inter group comparisons were done using tukeys multiple comparision. ‘P’ value<0.05 was considered statistically significant. Results: Flexural strength of Filtex Z350 XT before radiation was170.89±9.07.Flexural strength of Filtex Z350 XT after irradiation with 1KGy, 3KGy and 5KGy was found to be 269.06±94.91, 326.53±54.74 and 377.64±74.5 respectively. P value statistically significant (P<0.0001). Flexural strength of Ceram X duo before radiation was120.14±7.12.Flexural strength of Ceram X duo after irradiation with 1KGy, 3KGy and 5KGy was found to be 206.27±76.38, 177.31±67.35 and 229.33±59.15 respectively. P value statistically significant (P<0.0001). Conclusion: It can be concluded that electron beam irradiation can be used as a tool to modify the present day dental materials for enhancing their mechanical properties.
ABSTRACT
Aim: The aim of this study was to evaluate the cytotoxicity of three resin luting agents Rely X luting cement, Rely X luting 2 cement and Clearfil SA luting cement before and after electron beam irradiation. Materials and Methods: Growth and maintenance of cell cultures of human pulp cells was done in Dulbecco’s modified Eagle’s Medium (DMEM). The test samples were divided into two Categories: Irradiated Category and Non-radiated Category. Samples in Irradiated category were exposed to electron beam radiation at 200Gy. Three subgroups of radiated category and non radiated category were made. All the samples were subjected to MTT assay and spectrophotometric analysis and their cytotoxicity was assessed. Statistical analysis was done using t test. Results: Evaluation of Rely X luting Cement showed that radiated samples of powder, liquid and set cements showed decreased cell viability than non radiated samples. In Case of Rely X luting 2 cement, radiated samples showed increased cell viability for Paste A and Paste B samples. But in set material, irradiated samples showed decreased cell viability as compared to non radiated samples. For Clearfil SA luting Cement, Paste B showed increased cell viability for radiated samples. Paste A and Set cement of radiated samples showed decreased cell viability than non radiated samples. Conclusion: In the present study , the increased cytotoxicity of irradiated samples may be due to increase in the release of unbound monomers which may be due to chain breakage after irradiation and a reduction in the cytotoxicity which may be due to the cross linking of unbound monomers during irradiation.
ABSTRACT
Context: Oxidative stress is defined as an imbalance between the production of reactive oxygen species and antioxidant defense systems which are widely recognized as an important feature of many diseases including dental caries, suggesting that total antioxidant status may be of importance in determining the progression of caries. Aim: The aim of this study was to estimate the total antioxidant capacity (TAC) in saliva and serum of caries-free and caries-active adults and to correlate the TAC level with DMFT index (D = decayed, M = missing, F = filled, T = teeth). Settings and Design: The present study included 100 healthy adults who were divided into four groups: Control, group I, group II, and group III, with a DMFT index 0, <3, <10, and >10, respectively. Materials and Methods: Saliva and serum samples were collected from all the four groups. The TAC of saliva and serum was estimated by phosphomolybdenum method. Statistical Analysis Used: One-way analysis of variance (ANOVA) was used to compare the TAC of saliva and serum. Only differences with "P" < 0.05 were considered statistically significant. Results: The mean TAC level of both saliva and serum increased significantly (P < 0.001) with the DMFT index. Conclusion: Total antioxidant capacity of saliva has a linear relation with caries, i.e., as the severity of caries increases, the TAC level also increases.