Chemical characterization of silanized silver nanoparticles impregnated in poly (methyl methacrylate) resin: An in vitro study.

Aim: The intention was to determine the chemical interaction of silanized AgNPs with PMMA by Fourier transform infrared (FTIR) spectroscopy. Settings and Design: In-vitro comparative study. Materials and Methods: This study is composed of four groups - 0.75% AgNP, 1.0% AgNP, 1.5% AgNP impregnated with PMMA, and nonimpregnated PMMA as control. The chemical nature of silanized AgNPs was studied using FTIR study. Results: The results showed the appearance of new peak between 1727/cm and 1436/cm, i.e., 1636.476/ cm, 1645.886/cm, and 1646.885/cm, representing the C = C stretch in the experimental groups, i.e., 2, 3, and 4, respectively. This peak confirms that coupling agent has chemically interacted with PMMA. Conclusion: It can be concluded that the AgNPs coated with the silane coupling agent TMSPM has chemically reacted with PMMA.

Evaluation of the In-Vitro Cytotoxicity of Heat Cure Denture Base Resin Modified with Recycled PMMA-Based Denture Base Resin.

Aim: The aim of the present study was to evaluate the in-vitro cytotoxicity of heat-cure denture base resin (PMMA) modified with recycled denture base resin at 10%, 20%, 30%, 40%, and 50% (w/w) concentration. Materials and Methods: A total of 30 disk-shaped specimens were prepared and divided into six groups (n = 5). The Control group (R0) consisted of unmodified processed denture base resin, the experimental group consisted of denture base resin processed with substitution of 10% 20%, 30%, 40%, and 50% (w/w) of recycled denture base resin (R10, R20, R30, R40, and R50). Eluates were prepared using five sterile specimens of each group. The mouse fibroblast cell line (L929) was seeded in a 96-well cell plate system at a concentration of 1 × 104 cells/well in the DMEM medium with 1× antibiotic and antimycotic solution and 10% fetal bovine serum at 37°C with 5% CO2 and incubated in a CO2 incubator for 48 h. MTT assay was applied and the absorbance was measured at 570 nm using a microplate reader to assess the in-vitro cytotoxicity. One-way analysis of variance (ANOVA) along with post hoc Scheffe test was used to statistically compare the mean optical density (OD) values and cell survival/viability % amongst the groups. Results: No statistically significant difference was observed in the mean and standard deviation of the optical density and cell viability % of the test groups that were compared. Conclusion: Modification of denture base resin using recycled PMMA does not have a cytotoxic effect on the mouse fibroblast cell line L929.

Analysis of Surface Morphology and Elemental Composition on Zirconia Implants Before and After Photofunctionalization by Scanning Electron Microscopy and Energy Dispersive X ray Spectroscopy - An In vitro Study.

BACKGROUND: The purpose of this study is to analyze the surface morphology and elemental composition of zirconia implants before and after photofunctionalization. MATERIALS AND METHODS: Ten zirconia implants (white sky implant system- Bredent Company) five each in the study group and control group was taken. Study group samples were treated with ultraviolet light for 48 h. Microstructured surface of the study and control group blanks at abutment and thread regions were documented by Scanning Electron Microscope The semi-quantitative element composition was analyzed using Energy-dispersive X-ray (EDX) spectrum. RESULTS: SEM images of the study and control group divulged a varied array of topographical configuration of the abutment area and thread region at different magnifications. At low magnification, both study and control group revealed plain compact surface and wavy porous area, whereas higher magnification showed dense grainy regions of various sizes and intensities disrupted by pores. EDX spectrum analysis for elemental composition showed increased oxygen concentration in the study group (42.8%) than the control group (29.09%), whereas carbon concentration was lower in photofunctionalized group (34.34%) than in the control group (45.41%). CONCLUSION: In zirconia implants, photofunctionalization is a viable method to effectively enhance the surface topography and hydrophilicity of bone-implant interface.

Analysis of Surface Roughness and Three-dimensional Scanning Topography of Zirconia Implants before and after Photofunctionalization by Atomic Force Microscopy: An In Vitro Study.

AIM: To analyze surface roughness and three-dimensional (3D) scanning topography parameters of zirconia implants before and after photofunctionalization by atomic force microscopy (AFM). MATERIALS AND METHODS: Ten commercially available zirconia implants five each in the study and control group were taken. The study group was subjected to ultraviolet (UV) radiation for 48 h using the shorter wavelength of 254 nm. After washing all the implants with 70% alcohol and drying, 3D surface topography and roughness parameters were analyzed using CSC 17 probe AFM at three different magnifications 25 µm, 50 µm, and 80 µm, respectively. RESULTS: The surface topography and calculated mean amplitude, spatial, and hybrid parameters of the study group were higher than the control group (P < 0.05) in all three magnifications. Up to scale depth and peak value for the study and control group were (-0.4-0.4: -2-1) (-0.75 to 0.6:-1-1.3) (-0.75--0.5: -1.5-1.3) for the study and control group at 25, 50, and 80 µm magnification, respectively. This indicates that photofunctionalization increased surface roughness of Zirconia implants to desirable extent. CONCLUSION: There is a definite difference in the quantitative topographic characteristics with zirconia implants being microroughned after photofunctionalization (UV treatment).

Detection and Categorization of Biofilm-forming Staphylococcus aureus, Viridans streptococcus, Klebsiella pneumoniae, and Escherichia coli Isolated from Complete Denture Patients and Visualization Using Scanning Electron Microscopy.

AIMS: Complete denture patients have a plethora of microorganisms inhabiting their complete dentures. Some bacteria are capable of causing systemic illness such as aspiration pneumonia and infective endocarditis. Hence, detection as well as the categorization of biofilms, which form on the denture surface is vital in the study of denture biofilm-associated local and systemic diseases. This study aimed at the detection and categorization of biofilm-forming Staphylococcus aureus, Viridans streptococcus, Klebsiella pneumoniae, and Escherichia coli isolated from complete dentures and visualization of biofilms using scanning electron microscopy (SEM). MATERIALS AND METHODS: Thirty complete denture patients were selected for the study and swabs were collected from their complete denture surfaces. Isolation of the bacteria was done using selective media and confirmed using biochemical tests and 16SrRNA sequencing. The bacteria were subjected to biofilm assays via Microtiter plate assay. The biofilm-forming bacteria were categorized as weak, moderate, and strong biofilm formers based on optical density (OD) values. As a visual confirmation of the biofilms, scanning electron microscopic (SEM) images were taken for each of the strong biofilm-forming bacteria. Descriptive statistical analysis was carried out with the help of Statistical Package for the Social Sciences (SPSS) statistical package version 20.0. RESULTS: The average OD of S. aureus was 1. 333±0. 015 and the average OD of V. streptococcus species was 1. 304 ± 0.023. The average OD value of K. pneumoniae was 0.8 ± 0.012 and the average value of E. coli was 1.014 ± 0.01. CONCLUSIONS: The study of biofilms especially the strongly biofilm formers is very useful to understand the potential pathogenic effect of biofilms. These biofilms cause the systemic spread of the planktonic bacteria which could lead to systemic diseases that are resistant to conventional treatment. This could be due to the inherent nature of the biofilm to offer drug resistance to existing antibacterial agents.

Effect of novel cycloaliphatic comonomer on the flexural and impact strength of heat-cure denture base resin.

This study aims to evaluate the impact of adding a novel tricyclodecane dimethanol diacrylate comonomer on the flexural strength (FS) and impact strength (IS) of heat-cure denture base resin at 10% and 20% (v/v) concentrations. To test the FS and IS, a sum total of 150 bar-shaped specimens were prepared according to standard specifications. For the FS, the specimens were subjected to the three-point bend test with a span length of 50 mm. For the IS, Charpy's test was executed with a span length of 60 mm. The FS was measured in MPa, and the IS was measured in kJ/m2. There was a statistically significant difference (P < 0.001) between the control and experimental groups in that both the FS and IS were increased in the experimental groups relative to the control group.

Surface Modification Techniques for Zirconia-Based Bioceramics: A Review.

Zirconia is gaining interest as a ceramic biomaterial for implant applications due to its biocompatibility and desirable mechanical properties. At present, zirconia-based bioceramics is often seen in the applications of hip replacement and dental implants. This article briefly reviews different surface modification techniques that have been applied to zirconia such as polishing, sandblasting, acid etching, biofunctionalization, coating, laser treatment, and ultraviolet light treatment. The potential of surface modification to make zirconia a successful implant material in the future is highly dependent on the establishment of successful in vitro and in vivo studies. Hence, further effort should be made in order to deepen the understanding of tissue response to implant and tissue regeneration process.

Comparative study of evaluation of the oral stereognostic ability between diabetic and nondiabetic complete denture wearers with and without denture.

BACKGROUND: The diabetic subjects would have impaired oral stereognostic ability (OSA) compared with normal subjects due to diabetic neuropathy and microcirculatory disturbances. This study was conducted to compare the OSA between diabetic and nondiabetic complete denture wearers with and without denture. MATERIALS AND METHODS: In this in vivo study the present comparative study comprised of seventy edentulous subjects (36 males and 34 females), aged from 35 to 84 rehabilitated with complete dentures (among them 35 were diabetic and 35 subjects were nondiabetic complete denture wearer). The OSA tests were conducted using acrylic test samples of 12 shaped forms, which were placed in patient's mouth for a given period of time for identification and scored according to three-point scale as OSA score and the identification time was also recorded. The data obtained were analyzed using Chi-square test, t-test, and Pearson's correlation coefficient (P < 0.05). RESULTS: In this study, diabetic complete denture wearers got the mean OSA score of 12.43 ± 3.93 without dentures, which was lower than nondiabetic complete denture wearer group (14.82 ± 4.44). There was a significant difference (P = 0.020*) in the identification of test pieces. CONCLUSION: Within limitations of this study, diabetic complete denture wearers showed decreased OSA than nondiabetic subjects, particularly it was significant while not wearing dentures. Oral stereognosis may be used as one of the clinical aids in predicting patient's performance to a prosthesis. Based on their response, we can educate the patient about the prognosis.

Effect of Chemical Denture Disinfectants and Tree Extracts on Biofilm-forming Staphylococcus aureus and Viridans Streptococcus Species Isolated from Complete Denture.

AIMS: The present study aims at recording the antibacterial efficacy of various disinfectants used at different time periods against Staphylococcus aureus and viridans streptococcal species of bacteria isolated from complete dentures. MATERIALS AND METHODS: Fifty complete denture patients were selected for the study and swabs were collected from their complete denture surfaces. The isolated bacteria were subjected to six experimental groups which includes four groups of chemical denture disinfectants and two tree extracts groups. Isolation of the bacteria S. aureus and viridians streptococcal species was done by means of selective media and confirmed by means of biochemical tests. The bacteria were subjected to biofilm assays. The biofilm-forming bacteria with optical density (O.D.) values of more than 1.5 were selected for the study. About 150 acrylic specimens were fabricated and were contaminated by the 2 isolated bacteria mentioned above. The contaminated samples were disinfected by immersion for 10, 20, and 30 minutes in six disinfectants, namely: (1) 1% sodium hypochlorite, (2) 2% chlorhexidine, (3) 2% glutaraldehyde, (4) 3.8% sodium perborate, (5) 2% aalam extract, and (6) 2% neem extract. RESULTS: ANOVA test was performed for both S. aureus and viridans streptococcal species with regard to various synthetic and tree extracts as well as time duration of disinfection. F values for disinfection vs S. aureus is 205.4 (p < 0.001) and the relevant Scheffe post hoc test values is in the following order: 3 < 1, 4 < 6, 2 < 5. F values for disinfection vs viridans streptococcal species is 364.7 (p < 0.001) and the relevant Scheffe post hoc test values is in the following order: 3 < 4 < 1, 6, 2 < 5. CONCLUSION: For biofilm-forming S. aureus, 2% glutaraldehyde showed best antibacterial efficacy which was followed by 1% sodium hypochlorite and 3.8% sodium perborate. When it comes to biofilm-forming viridans streptococcal species, 2% glutaraldehyde showed best antibacterial efficacy. Next to 2% glutaraldehyde, 3.8% sodium perborate exhibited good disinfection potential. CLINICAL SIGNIFICANCE: Complete denture patients have a plethora of microorganisms habitating their complete dentures. Some bacteria are capable of causing systemic illness such as aspiration pneumonia and endocarditis. Hence, constant removal and disinfection of biofilms from the denture surface is vital to the local and systemic wellness of the patient. The most common bacteria capable of causing pneumonia and endocarditis that are isolated from complete dentures include S. aureus and viridans streptococcal species. The present study evaluates antibacterial efficacy of different disinfection agents especially against these biofilm-forming bacteria for different time periods. How to cite this article: Andonissamy L, Karthigeyan S, Ali SA, et al. Effect of Chemical Denture Disinfectants and Tree Extracts on Biofilm-forming Staphylococcus aureus and Viridans Streptococcus Species Isolated from Complete Denture. J Contemp Dent Pract 2019;20(11):1307-1314.

Cumulative effect of microwave sterilization on the physical properties of microwave polymerized and conventional heat-polymerized acrylic resin.

AIMS: To evaluate and compare the flexural strength and impact strength of conventional and microwave cured denture base resins before and after repeated sterilization using microwave energy to consider microwave curing as an alternative to the conventional method of sterilization. MATERIALS AND METHODS: The conventional heat cure acrylic resin (DPI heat cure material) Group A and microwave-polymerized acrylic resin (Vipi Wave Acrylic resin) Group B were used to fabricate 100 acrylic resins samples using a standard metal die of (86 mm × 11 mm × 3 mm) dimensions. The criterion was flexural strength and impact strength testing which had Group A and Group B samples; 50 samples for flexural strength and 50 samples for impact strength measurement. For each criterion, five control samples were taken for Group A and Group B. The samples were stored in water before experimenting. The test samples were subject to four cycles of microwave sterilization; followed by flexural strength testing with a 3-point flexural test in universal testing machine (UNITEK 94100) and impact strength testing with impact testing machine (ENKAY Pr09/E1/16). RESULTS: The physical properties had significant changes for conventionally cured denture base resins, whereas no changes found for microwave-cured resins after repeated sterilization cycles.

Comparison of flexural strength in three types of denture base resins: An in vitro study.

AIM: The aim of this study was to evaluate whether the flexural strength of a commercially available, heat polymerized acrylic denture base material could be improved using reinforcements. MATERIALS AND METHODS: A total of 30 specimens (65 mm × 10 mm × 3 mm) were fabricated; the specimens were divided into three groups with 10 specimens each. They were Group 1 - conventional denture base resins, Group 2 - high impact denture base resins, and Group 3 - glass reinforced denture base resins. The specimens were loaded until failure on a three-point bending test machine. An one-way analysis of variance was used to determine statistical differences among the flexural strength of three groups. Data were analyzed by SPSS software version 21.0© (IBM Corporation, Armonk, NY, USA) and the results were obtained. RESULTS: The flexural strength values showed statistically significant differences among experimental groups (P < 0.005). CONCLUSION: Within the limitations of the study polymethyl methacrylate (PMMA) reinforced with glass fibers showed the highest flexural strength values this was followed by PMMA reinforced with butadiene styrene, and the least strength was observed in the conventional denture base resins.

A newer technique to program a semi adjustable articulator.

INTRODUCTION: The difficulty in reproducing accurate angle of condylar guidance in semi-adjustable articulators. PURPOSE: The purpose of this study was to determine the correlation between the angle of horizontal condylar inclination obtained on a semi-adjustable articulator and the corresponding angle traced on a temporomandibular joint (TMJ) radiograph in completely edentulous subject. MATERIALS AND METHODS: The horizontal condylar inclination angle was obtained in a semi-adjustable articulator by means of height tracer (extra oral tracing device) and interocclusal records to program the articulator in 21 subjects. TMJ radiograph were recorded by the same operator with same orthopantomogram (OPG) machine (planmeca). Tracings of inclines of articular eminence on the radiograph were compared with the angle obtained on a semi-adjustable articulator. Each measurement was made using manual methods of measuring angle. The results were subjected to the Pearson correlation statistical analysis (α =0.01). RESULTS: The outline of the articular eminence in a TMJ tomogram radiographic image was identified and traced. A significant correlation was found between the horizontal condylar inclination on a semi-adjustable and the corresponding TMJ tomogram radiographic image for both right (R = 0.789; P = 0.001) and left (i = 0.747; P = 0.004) sides. CONCLUSION: The articular eminence traced on a TMJ tomogram image represents the horizontal condylar inclination with a mean difference of 5° in 21 subjects evaluated.

Implant rehabilitation for atrophic maxilla: a review.

A severely atrophied maxilla presents serious limitations for conventional implant placement. This presents challenge to the surgeon for implant placement in harmony with the planned prosthesis. Survey of various literatures using internet sources, manual searches, and common textbooks on dental implants shows, that a thorough knowledge of conventional augmentation procedures such as bone augmentation techniques, guided bone regeneration, alveolar distraction, maxillary sinus elevation techniques with or without grafting and contemporary techniques of implant placement provide effective long-term solutions in the management of the atrophic maxilla.

Evaluation of the inclination of maxillary occlusal plane on mounted casts using a fixed value and customized nasion indicator in artex articulator: Facebow system - An in-vivo comparative study.

AIM: To evaluate and compare the variations in the inclination of occlusal plane of casts mounted on Artex articulator using a facebow with a fixed value and customized nasion indicator. MATERIALS AND METHODS: Twenty two subjects were selected for this investigation. Two maxillary impressions were made, and casts poured. For each of the twenty two subjects, the facebow records were made with, Artex face-bow using a fixed value nasion indicator and customized nasion indicator and mounted. The angle between the occlusal plane of upper cast and the upper articulator arm was measured with a Universal bevel protractor and compared with the gold standard cephalometric value. RESULTS: It shows that, when angle was measured between maxillary occlusal plane and upper member of the articulator, on the mounted cast using a customized nasion indicator and fixed value nasion indicator against the gold standard cephalometric value as a whole, it was found to be not significant. But, if each patient were evaluated individually, there found to be the difference in the angle. DISCUSSION AND CONCLUSION: Variation in occlusal plane was very minimal and close to the cephalometric value when using customized nasion indicator compared to fixed value nasion indicator on the Artex.

An organized start to implant-supported prosthesis.

Various treatment options are available for rehabilitating the complete edentulous patients with implants. However, due consideration for the prosthesis is not given prior to implant surgery. This can result in implant being placed in locations that do not provide the best esthetic and functional result. Incorrect implant localization and angle are the primary cause of non-axial loading and may contribute to loss of Osseo-integration. For predictable outcome, the treatment should begin with visualizing the end result. A step-wise pre-implant surgery evaluation is necessary to achieve the objectives. This is a case report of a completely edentulous patient who was treated with fixed implant prosthesis following various steps in the pre-implant surgery evaluation.

Effect of simulated microwave disinfection on the mechanical properties of three different types of denture base resins.

STATEMENT OF PROBLEM: Disinfection of prostheses with chemical solutions has deleterious effects on dentures. The appropriate power setting of microwave for disinfection, without affecting denture base properties, is a controversy. PURPOSE: To evaluate and compare the effect of simulated microwave disinfection at a recommended power setting on the mechanical properties of three denture base heat polymerized acrylic resins. MATERIAL AND METHODS: Ninety rectangular specimens of each acrylic resin of 65mm × 10mm × 3 mm dimensions were divided into three groups. Group A (Trevalon), Group B (Trevalon- HI), Group C (Ivocap). In each group, thirty specimens were divided into three subgroups with ten specimens in each and they were submitted to MicroVickers hardness, flexural strength, and impact strength tests. In each subgroup, five specimens were tested before the simulated microwave disinfection and they served as the control group. The remaining five were tested after simulated microwave disinfection and they were considered as the experimental group. Simulated microwave disinfection was done in a domestic microwave oven at 650 W for 5 minutes. RESULTS: The data were analyzed using One-way ANOVA and t-test. The mechanical properties of the three denture base resins were not altered after simulated microwave disinfection, as compared to those of the controls. CONCLUSION: Microwave irradiation at 650 W for 5 min did not affect the mechanical properties of the three denture base resins. Domestic microwave oven, at the prescribed setting, can be used as an alternative method of disinfection for complete dentures without affecting their properties.

The effect of repeated immersion of gypsum cast in sodium hypochlorite and glutaraldehyde on its physical properties: An in vitro study.

BACKGROUND: One method used to disinfect a dental cast is immersion in a disinfecting solution. Repeated immersion of a cast in disinfectant may affect its physical properties. PURPOSE: The purpose of this study was to evaluate the changes in dimensional accuracy and hardness of the dental casts as a result of repeated disinfection in 0.525% sodium hypochlorite and 2% glutaraldehyde solutions. MATERIALS AND METHODS: Sixty specimens were made of type III dental stone. Twenty specimens were immersed in slurry, a supernatant solution of calcium sulfate in distilled water (control casts), 20 specimens in 0.525% sodium hypochlorite, and 20 specimens in 2% glutaraldehyde solutions for 30 min and air dried for 24 h. This process was repeated for 7 times for testing. Linear dimensional change and hardness were determined according to American National Standards Institute/American Dental Association (ANSI/ADA) standards. The data were analyzed using two-way analysis of variance. RESULTS: For specimens prepared with type III stones, treatment was by immersion in slurry (group I - control casts), and by immersion in 0.525% sodium hypochlorite (group II - test group 1) and in 2% glutaraldehyde solution (group III - test group 2). The specimens treated with sodium hypochlorite and glutaraldehyde showed more linear dimensional change compared to the specimens treated in slurry. However, the difference between test casts and control casts was significant. But the difference between the two test groups was not significant. Both the test groups showed decrease in hardness of the specimens compared to that specimens in control group. But the difference between two test groups was not significant in hardness. However,the values remained close to ANSI/ADA standards. CONCLUSION: The results demonstrated that repeated immersion of type III dental stone specimens in slurry with distilled water, 0.525% sodium hypochlorite and 2% glutaraldehyde, along with drying in air, caused a significant increase in linear dimension and a significant decrease in hardness.