scholarly journals Comparative Evaluation of Bond Strength between Ridge Lap Surface of Acrylic Teeth and Denture Base Resin: An In Vitro Study

2019 ◽  
Vol 07 (01) ◽  
pp. 012-018 ◽  
Author(s):  
Eeshita Sharma ◽  
Manjit Kumar ◽  
Rohit Sharma ◽  
Ajay Bansal ◽  
Sumit Katoch

Abstract Statement of Problem Acrylic teeth are preferred to porcelain teeth in dentures as they unite chemically with denture base resin, but their fracture from denture is common. Purpose The purpose of this study was to improve the bond strength of denture teeth to acrylic resin denture base by chemical or mechanical modification of the ridge lap surface of denture teeth. Materials and Methods Total 100 artificial cross-linked acrylic resin central incisors were divided into five groups: group A, 20 samples without modification (control group); group B, 20 samples (ridge lap surface of teeth treated with monomer); group C, 20 samples (ridge lap surface of teeth treated with monomer and the glaze layer removed with aluminum oxide abrasive stone); group D, 20 samples (ridge lap surface of teeth treated with dichloromethane); and group E, 20 samples (dichloromethane application followed by abrasion with aluminum oxide stone on ridge lap surface of teeth). They were mounted on wax blocks, and the blocks were acrylized. The bond strength values were obtained by subjecting the samples to shear compressive load under universal testing machine. Result The results were subjected to statistical analysis by applying analysis of variance and Bonferroni test for multiple group comparisons, and graphs were plotted. The mean value of bond strength was highest for group E (modified by aluminum oxide abrasion prior to dichloromethane application), followed by group C (modified by aluminum oxide abrasion prior to monomer application), group D (modified by dichloromethane application), group B (modified by monomer application), and lastly group A (control group). Significantly improved bond strength values were obtained in modified groups as compared with the control group. Conclusion Dichloromethane application followed by aluminum oxide abrasion provided the highest bond strength and is recommended to prevent debonding of the teeth from the denture base.

2015 ◽  
Vol 9 (1) ◽  
pp. 402-408 ◽  
Author(s):  
A.A.R. Khaledi ◽  
M. Bahrani ◽  
S. Shirzadi

Statement of the Problem: Bonding failure between acrylic resin and soft liner material and also gradual loss of soft liner resiliency over time are two impending challenges frequently recognized with a denture base embraced with a resilient liner. Since patients drink various beverages, it is crucial to assess the influences of these beverages on physical characteristics of soft liners. Purpose: This in vitro study envisioned to assess the influence of food simulating agents (FSA) on the hardness of a silicone soft liner by employing a Shore A durometer test and also evaluate its bond strength to a denture base resin by using tensile bond strength test. Materials and Methods: To test the hardness of samples, 50 rectangular samples (40 mm × 10 mm × 3 mm) were prepared from a heat-polymerized polymethyl methacrylate (Meliodent). Mollosil, a commercially available silicone resilient liner, was provided and applied on the specimens following the manufacturer’s directions. In order to test tensile bond strength, 100 cylindrical specimens (30 mm × 10 mm) were fabricated. The liners were added between specimens with the thicknesses of 3 mm. The specimens were divided into 5 groups (n=10) and immersed in distilled water, heptane, citric acid, and 50% ethanol. For each test, we used 10 specimens as a baseline measurement; control group. All specimens were kept in dispersed containers at 37ºC for 12 days and all solutions were changed every day. The hardness was verified using a Shore A durometer and the tensile bond strength was examined by an Instron testing machine at a cross-head speed of 5 mm/min. The records were analyzed employing one-way ANOVA, Tukey’s HSD, and LSD tests. Results: The mean tensile bond strength ± standard deviation (SD) for Mollosil was as follows for each group: 3.1 ± 0.4 (water), 1.8 ± 0.4 (citric acid), 3.0 ± 0.4 (heptane), 1.2 ± 0.3 (50% ethanol), and 3.8 ± 0.4 (control). The hardness values for each group were: 28.7 ± 2.11 (water), 33.2 ± 2.82 (citric acid), 39.2 ± 4.8 (heptane), 32.3 ± 3.56 (50% ethanol) and 22.2 ± 2.08 (control). Mean values for hardness indicated that all of the food simulating agents significantly increased hardness of the Mollosil soft liner compared to the control group (p<0.05). The results of tensile bond strength depicted that water and FSA decreased the bond strength of the soft liner -denture base resin compared to the control group and it was statistically significant (p<0.05). Conclusion: The food simulating agents could influence the mechanical properties of silicone soft liners; hence, clinicians should inform their patients concerning their possible adverse effects and complications.


2016 ◽  
Vol 17 (2) ◽  
pp. 154-159 ◽  
Author(s):  
Farzaneh Ahrari ◽  
Mohammadreza Nakhaei ◽  
Hossein Dashti ◽  
Samaneh Vasigh ◽  
Shazia Mushtaq ◽  
...  

ABSTRACT Aim The aim of this study is to evaluate the effects of three different surface treatments and thermocycling on the tensile strength of a silicone lining material to denture resin. Materials and methods A total of 96 cube-shaped specimens were fabricated using heat-cured polymethyl methacrylate (PMMA) denture base resin. Three millimeters of the material was cut from the midsection. The specimens were divided into four groups. The bonding surfaces of the specimens in each group received one of the following surface treatments: no surface treatment (control group), airborne particle abrasion with 110 μm alumina particles (air abrasion group), Er:yttrium aluminum garnet laser irradiation (laser group), and air abrasion + laser. After the lining materials were processed between the two PMMA blocks, each group was divided into two subgroups (n = 12), either stored in distilled water at 37°C for 24 hours or thermocycled between 5 and 55°C for 5,000 cycles. The specimens were tested in tensile and shear strength in a universal testing machine. Data were analyzed with two-way analysis of variance and Tamhane's post hoc tests (α = 0.05). The mode of failure was determined, and one specimen in each group was examined by scanning electron microscopy. Results Surface-treated groups demonstrated significantly higher tensile strengths compared to the control group (p < 0.001). Nonetheless, no significant differences were found between surface-treated groups (p > 0.05). The tensile strength was significantly different between thermocycled and waterstored specimens (p = 0.021). Conclusion Altering the surface of the acrylic denture base resin with air abrasion, laser, and air abrasion + laser increased the tensile strength. Thermocycling resulted in decrease in bond strength of silicone-based liner to surface-treated acrylic resin. Clinical significance Pretreatment of denture base resins before applying the soft liner materials improves the bond strength. However, thermocycling results in decrease in bond strength of soft denture liner to surface-treated acrylic resin. How to cite this article Nakhaei M, Dashti H, Ahrari F, Vasigh S, Mushtaq S, Shetty RM. Effect of Different Surface Treatments and Thermocycling on Bond Strength of a Silicone-based Denture Liner to a Denture Base Resin. J Contemp Dent Pract 2016;17(2):154-159.


2016 ◽  
Vol 27 (2) ◽  
pp. 169-176 ◽  
Author(s):  
Adaias O. Matos ◽  
Josiane O. Costa ◽  
Thamara Beline ◽  
Erika S. Ogawa ◽  
Wirley G. Assunção ◽  
...  

2015 ◽  
Vol 35 (4) ◽  
pp. 398-403 ◽  
Author(s):  
Y Alcaraz-Contreras ◽  
RP Mendoza-Lozano ◽  
ER Martínez-Alcaraz ◽  
M Martínez-Alfaro ◽  
MA Gallegos-Corona ◽  
...  

We studied the effect of silymarin and dimercaptosuccinic acid (DMSA), a chelating agent that was administered individually or in combination against lead (Pb) toxicity in rats. Wistar rats (200 ± 20) were randomly divided into five groups. Group A served as a control. Groups B–E were exposed to 2000 ppm of lead acetate in drinking water for 8 weeks. Group B served as a positive control. Group C received silymarin (100 mg kg−1 orally) for 8 weeks. Group D received DMSA (75 mg kg−1 orally) once daily for the last 5 days of treatment. Group E received DMSA and silymarin as groups C and D, respectively. The effect of Pb was evaluated and accordingly the treatments on blood lead levels (BLLs), renal system, and genotoxic effects were calculated using comet assay. The BLLs were significantly increased following the exposition of lead acetate. The administration of silymarin and DMSA provided reduction in BLLs. Silymarin and DMSA provided significant protection on the genotoxic effect of Pb. The toxic effect of Pb on kidneys was also studied. Our data suggest that silymarin and DMSA improve the renal histopathological lesions.


2021 ◽  
Vol 10 (2) ◽  
pp. 024-030
Author(s):  
Godwin Chinedu Uloneme ◽  
Demian Nnabuihe Ezejindu ◽  
Darlington Cyprian Akukwu ◽  
Amadi Chibundu Chiekezie

Background: The extract of Corchorus olitorius has a reasonable content of vitamins A and C, calcium, iron and fibre, and therefore enjoys a universal application in the treatment of some disease conditions, even as the whole leaf is a very important component of food in so many cultures. Purpose: The study was designed to investigate the effect of Corchorus olitorius extracts on the testis of adult Wistar rats. Method: A total number of thirty two adult Wistar rats weighing between 180 and 200 grammes separated into four groups labeled A,B,C and D respectively were used for the study. Animals in group A which served as the control group were fed with the normal rat chow and water only. The group B rats were administered 100mg/kg body weight of aqueous extract of Corchorus olitorus; while those in group C were administered 500mg/kg body weight of the extract. The group D rats received 1000mg/kg body weight of the extract. For a period of four weeks, the different experimental animal groups received the respective aforementioned treatments once daily, around nine- o’clock in the morning through oral intubation. At the end of the 28 day treatment, the animals were sacrificed and the testes harvested for histological, investigation, and through cardiac puncture, blood samples for some hormonal studies was also collected and investigated using standard laboratory standards. Results: Observations made showed that the extract produced no histological distortions, degenerative or defective effects on the testicular tissues. The testosterone levels of group B, C, and D rats were observed to be significantly higher (P<0.005) than that of the group A (control group).ound: The extract of Corchorus olitorius has a reasonable content of vitamins A and C, calcium, iron and fibre, and therefore enjoys a universal application in the treatment of some disease conditions, even as the whole leaf is a very important component of food in so many cultures. Purpose: The study was designed to investigate the effect of Corchorus olitorius extracts on the testis of adult Wistar rats. Method: A total number of thirty two adult Wistar rats weighing between 180 and 200 grammes separated into four groups labeled A,B,C and D respectively were used for the study. Animals in group A which served as the control group were fed with the normal rat chow and water only. The group B rats were administered 100mg/kg body weight of aqueous extract of Corchorus olitorus; while those in group C were administered 500mg/kg body weight of the extract. The group D rats received 1000mg/kg body weight of the extract. For a period of four weeks, the different experimental animal groups received the respective aforementioned treatments once daily, around nine- o’clock in the morning through oral intubation. At the end of the 28 day treatment, the animals were sacrificed and the testes harvested for histological, investigation, and through cardiac puncture, blood samples for some hormonal studies was also collected and investigated using standard laboratory standards. Results: Observations made showed that the extract produced no histological distortions, degenerative or defective effects on the testicular tissues. The testosterone levels of group B, C, and D rats were observed to be significantly higher (P<0.005) than that of the group A (control group).


2019 ◽  
Vol 13 (3) ◽  
pp. 200-207
Author(s):  
Vikram M. Belkhode ◽  
Sharayu V. Nimonkar ◽  
S. R. Godbole ◽  
Pranali Nimonkar ◽  
Seema Sathe ◽  
...  

Background. Dental porcelain has excellent esthetics in combination with biocompatibility and is one of the most commonly used restorative materials. Its low tensile strength remains a major drawback. The porcelain-fused-to-metal restorations have been introduced to increase the fracture resistance of dental porcelain. The aim of this study was to evaluate the effect of different surface treatments on the bond strength of a non-precious alloy to ceramic. Methods. The present cross-sectional observational study was conducted with forty samples of cobalt‒chromium that were fabricated with porcelain interposed between the two metal test pieces. The metal was subjected to combinations of different surface treatments. The samples group A (n=10) were not subjected to any surface treatments. Group B samples underwent sandblasting and surface grinding. Group C samples were subjected to sandblasting, surface grinding and degassing; and group D samples underwent sandblasting, surface grinding, ultrasonic cleaning and degassing. The tensile bond strength was measured in a universal testing machine, and a scanning electron microscope (SEM) was used to obtain images of the samples after surface treatment to determine the surface irregularities and after the debonding of the samples for the type of the bond failure. ANOVA was used for the statistical analysis. Results. The results showed significant variations in the tensile bond strength between the four groups (F=251.05, P=0.000). The SEM images of group A showed no surface irregularities; group C samples exhibited surface irregularities more than those in group B. Group D had the highest surface irregularities. SEM evaluations showed a statistically significant difference in the type of bond failure (P<0.001). Conclusion. Based on the results of this study, it can be concluded that the surface treatments on the metal increased the bond strength of the metal‒ceramic interface significantly. A combination of sandblasting, surface grinding and ultrasonic cleaning, followed by degassing, resulted in the highest tensile bond strength.


2021 ◽  
Vol 14 (10) ◽  
pp. 1508-1517
Author(s):  
Shan-Na Chen ◽  
◽  
Ying-Xue Ma ◽  
Song Chen ◽  
Guang-Hui He ◽  
...  

AIM: To investigate the protective effect of human umbilical cord mesenchymal stem cells (hUCMSCs) modified by the LIF gene on the retinal function of diabetic model rats and preliminarily explore the possible mechanism. METHODS: A stably transfected cell line of hUCMSCs overexpressing leukemia inhibitory factor (LIF) was constructed. Overexpression was verified by fluorescent quantitative polymerase chain reaction (qPCR). Forty-eight adult Sprague-Dawley rats were randomly divided into a normal control group (group A), streptozotocin-induced diabetic control group (group B), diabetic rats at 3mo injected with empty vector-transfected hUCMSCs (group C) or injected with LIF-hUCMSCs (group D). Four weeks after the intravitreal injection, analyses in all groups included retinal function using flash electroretinogram (F-ERG), retinal blood vessel examination of retinal flat mounts perfused with fluorescein isothiocyanate-dextran (FITC-dextran), and retinal structure examination of sections using hematoxylin and eosin staining. Expression levels of adiponectin (APN), high-sensitivity C-reactive protein (hs-CRP), and neurotrophin-4 (NT-4) in each group was detected using immunohistochemistry, PCR, Western blotting, and ELISA, respectively. RESULTS: A stable transgenic cell line of LIF-hUCMSCs was constructed. F-ERG and FITC-dextran examinations revealed no abnormalities of retinal structure and function in group A, severe damage of the retinal blood vessels and function in group B, and improved retinal structure and function in group C and especially group D. qPCR, ELISA, and Western blot analyses revealed progressively higher APN and NT-4 expression levels in groups B, C, and D than in group A. hs-CRP expression was significantly higher in group B than in groups A, C, and D, and was significantly higher in group C than in group D (P<0.05). CONCLUSION: LIF-hUCMSCs protect the retina of diabetic rats by upregulating APN and NT-4 expression and downregulating hs-CRP expression in the retina.


2020 ◽  
Vol 32 (1) ◽  
pp. 66
Author(s):  
Siti Wahyuni ◽  
Chairunnisa Ricca

Pendahuluan: Nilon termoplastik merupakan basis gigi tiruan yang banyak diminati oleh para dokter gigi karena memiliki beberapa keuntungan dibandingkan bahan basis gigi tiruan resin akrilik. Diantara jenis nilon termoplastik yang sering dijadikan basis gigi tiruan adalah poliamida 6 dan poliamida mikrokristalin. Poliamida Mikrokristalin merupakan poliamida generasi baru yang dibuat untuk menanggulangi kelemahan pada poliamida sebelumnya. Tujuan penelitian ini adalah menganalisis pengaruh minuman teh pada pengguna gigi tiruan nilon termoplastik terhadap penyerapan air dan stabilitas warna. Metode: Jenis penelitian ini adalah experimental laboratoris. Jumlah sampel terdiri dari 40 dengan  ukuran diameter 15 mm ± 1 mm dan ketebalan 0.5 mm ± 0,1 mm (ISO 4049) dan terbagi menjadi 4 kelompok (kelompok A poliamida 6 dan kelompok B poliamida mikrokristalin untuk penyerapan air serta kelompok C poliamida 6 dan kelompok D poliamida mikrokristalin untuk uji stabilitas warna). Semua sampel direndam dalam larutan teh selama 7 hari. Data dianalisis dengan uji T Independen. Gambaran mikroskopis sampel diuji dengan SEM Hasil: Berdasarkan uji T Independen hasil menunjukkan perbedaan yang signifikan diantara kelompok A dan B, C dan D.  Uji T independen menunjukkan perbedaan yang signifikan diantara kelompok A dan B, C dan D (p=0,0001, p<0,05) Simpulan: Terdapat pengaruh minuman teh pada pengguna gigi tiruan nilon termoplastik. Poliamida Mikrokristalin memiliki penyerapan air yang lebih sedikit dan stabilitas warna yang lebih baik dibandingkan Poliamida 6.Kata kunci: Nilon termoplastik, poliamida 6, poliamida mikrokristalin, penyerapan air, stabilitas warna, SEM. ABSTRACTIntroduction: Thermoplastic nylon is a denture base mostly demanded by dentists due to its several advantages over acrylic resin denture base material. Among the types of thermoplastic nylon that are often used as denture bases are polyamide 6 and microcrystalline polyamide. Microcrystalline polyamide is the new generation of polyamides created to overcome the weaknesses of previous polyamides. The purpose of this study was to analyse the effect of tea on thermoplastic nylon denture wearers on water absorption and colour stability. Methods: This research was experimental laboratory research on 40 samples with a diameter of 15 mm ± 1 mm, and a thickness of 0.5 mm ± 0.1 mm (ISO 4049), divided into four groups (Group A was the polyamide 6; Group B was the microcrystalline polyamide on the water absorption; Group C was polyamide 6; and Group D was microcrystalline polyamide on the colour stability). All samples were immersed in the tea solutions for 7 days. Data were analysed with independent t-test. The microscopic structure was analysed using the scanning electron microscope (SEM). Results: The results showed significant differences between group A, B, C, and D. The independent t-test also showed significant differences between group A, B, C, and D (p = 0.000; p < 0.05). Conclusion: There is an effect of tea on the thermoplastic nylon denture wearers. Microcrystalline polyamides have less water absorption and better colour stability than Polyamide 6.Keywords:  Polyamide 6, thermoplastic nylon, microcrystalline polyamide, water absorption, colour stability, SEM.


2012 ◽  
Vol 13 (6) ◽  
pp. 842-849
Author(s):  
T Shankar ◽  
N Venugopal Rao ◽  
Snigdha Gowd ◽  
Syed Tauqheer Ahmed ◽  
V Vinod ◽  
...  

ABSTRACT Aim The aim of this study is to evaluate the dimensional accuracy of heat polymerized acrylic resin denture base clamped by the conventional method and by new-press technique and cured by long curing cycle. Materials and methods In this study, a total of 60 standardized maxillary record bases were fabricated with seven reference points as follows: • Point A Incisive papilla, • Point B and C Canine region on either side • Point E and G Midpoint of tuberosities on either side • Point F Midpoint of the line joining the two tuberosities • Point D Midpoint between the line joining A and F Group A Ten maxillary record bases were fabricated by conventional clamping method and cured by long curing cycle. Group A’ Ten maxillary record bases were fabricated by New Press or RS tension clamping method and cured by long curing cycle. The distances between the reference points, i.e. A-B, A-C, A-D, D-F, B-E, C-G, E-F, F-G, B-D, D-G, C-D, D-E of all three thermoplastic denture base plates were measured and recorded with the help of travelling microscope and were used for comparison with the measured and recorded readings of processed acrylic denture bases. The data obtained was analyzed by using the one-way analysis of variance and HSD Multiple Comparison Test. Results The overall results of the study indicate that among all the denture bases cured by the two clamping systems and the long curing cycle, group A‘ were the most dimensionally stable, followed by control group A. Conclusion The study concluded that the denture bases fabricated by the New Press method using the long curing cycle would produce the most dimensionally stable denture bases. How to cite this article Shankar T, Gowd S, Ahmed ST, Vinod V, Goud MV, Rao NV. A Comparative Evaluation of the Dimensional Accuracy of Heat Polymerized Acrylic Resin Denture Base Clamped by the Conventional Method and by New-press Technique and Cured by Long Curing Cycle: An in vitro Study. J Contemp Dent Pract 2012;13(6):842-849.


2020 ◽  
Author(s):  
Obeagu Emmanuel Ifeanyi

The hematological features of Gongronema latifolium, aqueous leaves extract was evaluated using standard methods. After 10 days of consecutive infusions into 9 experimental animals (rabbits). The rabbits were monitored and the following parameters determined; hemoglobin (HB), PCV, Platelet, WBC, Differential White Blood Cell. The Rabbits were grouped into 4, one consisting of control (group A), group B was fed with 0.5 mg/kg, group C with 1.0 mg/kg, and Group D with 1.5mg/kg of the aqueous extract of Gongronemalatifolium. The mean values obtained for hemoglobin estimation for the control group is 5.9 ± 4.1 g/dl, 9.1 ± 2.9 g/dl for group B 10.2 ± 1.8 g/dl for group C and 12.8 ± 0.1 g/dl for group D with no significant increase on the PCV estimation, the mean value for the control (group A) is 17.7 ± 12.3%, 27.3 ± 8.7% for group B, group C (30.6 ± 5.4%) and D (28.4 ± 0.3) show increase that statistically significant (p > 0.01). the platelet counts of group C (600 ± 0 x 109/L) and D(600 ± 0 x 109/L) show significant increase (p > 0.01) when compared with the control (600 ± 00). But the platelet value of group B (550 ± 50 x 109/L) shows no difference. No significant changes were observed in the White Blood Counts of the test groups B (3.5 ± 0.5 x 109/L), C (1.9 + 2.1 x 109/L) and D(3.6 ± 0.4) when compared with the control group (2.9 ± 1.9). The values obtained from the differential White Blood Counts (Neutrophils, Lymphocytes, Eosinophils and Monocytes) were not significant. Therefore, Gongronemalatifolium, when properly taken as a nutritional diet, causes beneficial changes on hemoglobin, packed cell volumes and platelet counts of consumers.


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