Heat-cured Denture Base Material Research Articles

Effect of Surface Treatments with Plasma and Chemical Bond on Shear Bond Strength of Acrylic Denture Teeth to Flexible and Heat-Cured Denture Base Material: An In Vitro Study

Introduction: We aimed to evaluate the shear bond strength of acrylic denture teeth to flexible and heat-cured denture base material after surface treatments with argon plasma, chemical bonding agent (PALFIQUE universal), and combination. Methods: A total of 80 incisor acrylic denture teeth were treated with a argonplasma, chemical bond (PALFIQUE universal bond), and a combination with 10 samples for each group. The neck (gingival portion) of teeth was cut at a 45° angle, and the teeth were attached to heat-cured acrylic resin and flexible denture base material. All the specimens were stored in artificial saliva for 7 days in an incubator (37 °C). A shear bond strength test was conducted using an Instron universal testing machine. Data were analyzed by the analysis of variance (ANOVA) and the Tukey’s honest significant difference post hoc test using R 4.2.3. Results: A statistically significant difference was found among study groups regarding the type of base, surface treatment with bond, plasma, and combination of bond and plasma (P < 0.00). The Tukey’s test showed that in a heat-cured base, the difference between the control and surface treatment with bond was not significant (P > 0.05). Also, in the flexible base group, the difference between the control and surface treatment with plasma was not significant (P = 0.162). Conclusion: In heat-cured denture-base group, the shear bond strength increased significantly with the combination of surface treatment with argon plasma and a chemical bonding agent (PALFIQUE universal). In the flexible denture-base group, the shear bond strength increased significantly with use of a surface treatment with a chemical bonding agent (PALFIQUE universal).

Impact of surface treatments on the sorption and solubility of a heat-cured denture base material

Removable dentures fabricated from polymethylmethacrylate material are the most common prostheses used to treat edentulism worldwide. This research aimed to compare the sorption and solubility characteristics of a mechanically polished heat-cured acrylic denture material and a light-cured varnished material against non-treated material, all of which were soaked in distilled water. A total of 45 specimens were prepared and tested according to the ISO Standard 20795-1: 2013 (E) to test for sorption and solubility. The data were analysed through one-way analysis of variance (ANOVA) and Tukey-Kramer multiple comparison test.

Physical Properties of Additively Manufactured Tooth-Colored Material Attached to Denture Base-Colored Material in a Printed Monolithic Unit.

Additive manufacturing is an emerging technology that has been successfully used in dentistry for denture fabrication. However, the conventional issue of tooth debonding exists in additively manufactured dentures. In this study, we investigated the physical properties of conventional teeth attached to a heat-cured denture base material compared to additively manufactured tooth-coloured materials attached to denture base-coloured materials in a printed monolithic unit. We designed a model consisting of a tooth attached to a cylindrical base to fabricate the additively manufactured group and the conventional group. All groups were tested for fracture load before and after thermocycling, water sorption, solubility, and shape accuracy. The Mann-Whitney U test was used for statistical analysis. The fracture load of the additively manufactured group was significantly higher than that of the conventional group after thermocycling (p = 0.019). The water sorption of the conventional group was significantly lower than that of the additively manufactured group (p = 0.000), whereas there was no significant difference in the water solubility between them (p = 0.192). The shape accuracy of the additively manufactured group was significantly better than that of the conventional group (p < 0.05). In conclusion, additive monolithic manufacturing technology may provide an alternative way to enhance the fracture load between the teeth and denture bases.

Effect of simulated brushing and disinfection on the surface roughness and color stability of CAD-CAM denture base materials

PurposeTo evaluate the effect of simulated brushing and chemical disinfection on the surface roughness and color stability of CAD-CAM denture base materials and to compare with those of a heat-cured denture base material. Material and methodsDisk-shaped specimens (Ø 10mm × 2 mm) were prepared from 3 CAD-CAM denture base resins (AvaDent, Ava; Merz M-PM, Merz; Polident d.o.o, Poli) and a heat-cured polymethylmethacrylate resin (Promolux, Conv) (n = 30). After polishing, baseline surface roughness (Ra) and color coordinates were measured. The measurements were repeated after 20000 cycles of simulated brushing, and the specimens were divided into 3 groups according to disinfection protocol (distilled water, 1% sodium hypochlorite (NaOCl), and effervescent tablet) (n = 10). After 9 cleaning cycles over a period of 20 days, Ra and color coordinates were remeasured. Color differences (ΔE00) were calculated by using CIEDE2000 formula. One-way analysis of variance (ANOVA) and pairwise t-tests were used to analyze Ra and ΔE00 data, while repeated measures ANOVA test was used to compare baseline, after brush, and after disinfection Ra values (α = 0.05). ResultsBrushing did not affect the Ra values of tested materials (P ≥ .08). Both before and after brushing, Merz and Conv had higher Ra values than Poli and Ava (P < .001). Among disinfectants, effervescent tablet led to the lowest Ra for Merz (P = .003) and the highest Ra for Poli (P ≤ .039). Only NaOCl resulted in significant differences among the Ra of materials (P < .001), as Merz and Conv had higher Ra values than Poli (P ≤ .002). Repeated measures ANOVA revealed that effervescent tablet disinfection of Merz led to lower Ra values than those of baseline and after brushing (P ≤ .042). After brushing, Ava and Conv had higher ΔE00 values compared with Merz and Poli (P ≤ .015). When compared with other disinfection protocols, effervescent tablet led to higher ΔE00 values for Merz and Poli (P < .001). Significant differences were observed among materials when NaOCl was used; Conv had higher ΔE00 values than Ava and Merz (P = .004). ConclusionsBrushing did not increase the surface roughness of materials. Disinfection protocol's effect on the surface roughness varied. The effect of brushing on the color of materials varied; color of Ava and Conv was affected from brushing more than the other materials. Color stability of materials varied depending on the disinfection protocol. Effervescent tablet caused higher color change with Merz and Poli compared with other disinfectants. NaOCl led to small color change for Poli, Ava, and Merz materials.

Denture base materials surface roughness changes in response to exposure to cigarette smoke in an in vitro experiment

Aim: Denture base materials were subjected to cigarette smoke for the purpose of determining their surface roughness. Materials and Methods: Polymethylmethacrylate and flexible denture base materials were used to manufacture 40 specimens for this study (20 for each). Each sample was randomly assigned to one of four groups: control, flexible, and heat-cured denture base material samples. The heat-cured denture material samples were the only ones that had been exposed to cigarette smoke (subgroup III). There was a control group for each group. For the smoke test groups, distilled water was utilised, whereas cigarette smoking was used for the water test groups. Each participant in the trial was exposed to six cigarettes in a specially created smoking area. Surface roughness differences between pre- and post-smoking samples were analysed using a profilometer. The data was analysed using a paired comparison and an independent comparison. Groupings differed significantly in their initial roughness and final roughness, according to results from a paired t-test. Conclusion: Surface harshness of tobacco-smoke-exposed specimens of both the intensity-restored and the adaptive dental replacement base materials was greater.

3D-Printed vs. Heat-Polymerizing and Autopolymerizing Denture Base Acrylic Resins.

The aim of this work was to investigate the effect of two post-curing methods on the mechanical properties of a 3D-printed denture base material. Additionally, to compare the mechanical properties of that 3D-printed material with those of conventional autopolymerizing and a heat-cured denture base material. A resin for 3D-printing denture base (Imprimo®), a heat-polymerizing acrylic resin (Paladon® 65), and an autopolymerizing acrylic resin (Palapress®) were investigated. Flexural strength, elastic modulus, fracture toughness, work of fracture, water sorption, and water solubility were evaluated. The 3D-printed test specimens were post-cured using two different units (Imprimo Cure® and Form Cure®). The tests were carried out after both dry and 30 days water storage. Data were collected and statistically analyzed. Resin type had a significant effect on the flexural strength, elastic modulus, fracture toughness, and work of fracture (p < 0.001). The flexural strength and elastic modulus for the heat-cured polymer were significantly the highest among all investigated groups regardless of the storage condition (p < 0.001). The fracture toughness and work of fracture of the 3D-printed material were significantly the lowest (p < 0.001). The heat-cured polymer had the lowest significant water solubility (p < 0.001). The post-curing method had an impact on the flexural strength of the investigated 3D-printed denture base material. The flexural strength, elastic modulus, fracture toughness, work of fracture of the 3D-printed material were inferior to those of the heat-cured one. Increased post-curing temperature may enhance the flexural properties of resin monomers used for 3D-printing dental appliances.

Impact strength of 3D printed and conventional heat-cured and cold-cured denture base acrylics.

To evaluate and compare the impact strength of 3D-printed resin to conventionally fabricated denture bases of heat-cured and cold-cured acrylic resin. Denture base materials were evenly divided into three groups (n = 25 each; N = 75): (1) 3Dprinted material (Denture Base LP, Formlabs); (2) Heat-cured acrylic resin (Lucitone 199, Dentsply Sirona); and (3) cold-cured acrylic resin (Lucitone HIPA, Dentsply Sirona). The 3Dprinted specimens were designed through computer-aided design (CAD) software (Autodesk Meshmixer) with the dimensions 64 mm long, 12.7 mm wide, and 3.2 mm thick, then printed with a desktop stereolithography printer (Form 2, Formlabs). Heat-cured and cold-cured acrylic resin specimens were fabricated through conventional (compression and pouring) methods. The impact energy was read directly from the impact tester in joules, and the cross-sectional area of each specimen was used to calculate the impact strength in kJ/m2. Analysis of variance, Tukey multiple comparisons test, and a likelihood ratio α = .05 were conducted. The average mean impact strength was 8.9 kJ/m2 for heat-cured acrylic resin, 11.2 kJ/m2 for 3D-printed resin, and 14.9 kJ/m2 for cold-cured acrylic resin. Tukey multiple comparisons test showed that the impact strength for the cold-cured group was significantly greater than the 3D-printed resin and heat-cured acrylic resin groups. Within the limitations of this study, the cold-cured acrylic (Lucitone HIPA) showed the greatest impact strength, followed by 3D-printed resin (Denture Base LP) and conventional heat-cured denture base materials (Lucitone 199), respectively.

Evaluation of Color Change of Heat Cured Denture Base Material Incorporated with Novel Silver Nanoparticles Submitted to Accelerated Aging

Purpose:to investigate and compare the influences of adding different concentrations of colloidal forms silver nanoparticles on color changes of heat cured acrylic resin denture base material submitted to Accelerated aging. Methods: A total of 40 disc-shaped specimens were prepared from heat cured PMMA resins with different concentration of silver nanoparticles. A double beam ultra-violet visible spectrophotometer was used to obtain diffuse reflectance data at every 5nm between 400-700nm. The results were recorded using a computer color matching system (CCM) and tabulated for the statistical analysis of the color differences (ΔE) data. Comparisons between the different studied groups were analyzed using F-test (ANOVA) and Post Hoc test (Scheffe) for pair-wise comparisons. Significance of the obtained results was judged at the significance level of α = 0.05. Results: All groups of heat-cured acrylic resin with the addition of (NAg) groups II, III and IV were showed significant (ΔE) values more than group I at initial and at stage I, II of accelerated aging records. In stage III only group IV was showed significant (ΔE) values more than group I of the same stage. Therefore, group IV was showed significantly highest mean (ΔE) value followed by group III then group II (P < 0.05) in all accelerated aging stages but group I was showed significantly lowest mean (ΔE). Conclusion: The silver nanoparticles incorporation within the acrylic denture base material can change its color. The higher incorporation of silver nanoparticles with accelerated aging, the more color difference values (ΔE) of the acrylic resin denture.

Effect of cigarette smoke on the surface roughness of two different denture base materials: An in vitro study.

Aim:This study aimed to evaluate the effect of cigarette smoke on the surface roughness of two commercially available denture base materials.Materials and Methods:A total numbers of 40 specimens were fabricated from two commercially available denture base materials: heat-cured polymethylmethacrylate and flexible denture base materials (20 for each). The specimens for each type were divided into four subgroups: subgroup I, heat-cured denture base material specimens (control group); subgroup II, flexible denture base material (control group); subgroup III, heat-cured denture base material specimen exposed to cigarette smoking group; and subgroup IV, flexible denture base material specimens exposed to cigarette smoking. The control groups were used for immersion in distilled water, and the smoke test groups were used for exposure to cigarette smoking. The smoke test group specimens were exposed to smoking in a custom-made smoking chamber using six cigarettes for each specimen. The surface roughness was measured using a profilometer, and the measurements were considered as the difference between the initial and final roughness measured before and after smoking. Paired t test and independent t-test were used to interpret differences in initial and final roughness values within and between groups respectively.Results:Paired t-test showed a significant difference between initial surface roughness and final surface roughness within each subgroup.Conclusion:The surface roughness of the specimens fabricated from the flexible denture base material was found to be more compared to heat-cured denture base specimens after exposure to cigarette smoke.

Maxillary denture flange and occlusal discrepancies of Vertex ThermoSens in comparison with conventional heat-cured denture base materials.

This study was conducted to investigate the maxillary denture bases and occlusal discrepancies using the Vertex Thermosens in comparison with the conventional polymethyl-methacrylate materials. Twenty maxillary denture bases were prepared from the Vertex ThermoSens and a conventional heat-cured denture base materials. Acrylic maxillary second molars were arranged in their respective positions on the ridge. After curing of both types of denture bases, they were deflasked with their respective master casts. Reference points were prepared for measurements of the antero-posterior and cross-arch dimensions at the denture borders using caliper device. Furthermore, the teeth discrepancies were measured between reference points in the ligual aspect of the second maxillary molars. The recorded data was analyzed using SPSS statistical software version 20. The results showed initial shrinkage of both denture bases in the antero-posterior and cross-arch dimensions immediately after decasting. This contraction was compensated gradually during storage in water up to 2 weeks. Regarding the variable time, there was a significant difference between the tested materials. Moreover, the results revealed occlusal discrepancies and shifting of teeth inward immediately after decasting, followed by outward movement after storage in water for 2 weeks. Regarding the variables time and materials, there were significant differences. Both materials exhibited inward shrinkage in the antero-posterior and cross-arch dimensions immediately after decasting. Both denture bases showed inward shifting of teeth immediately after decasting, followed by outward movement after storage in water up to 2 weeks.

The influence of polishing techniques on pre-polymerized CAD\CAM acrylic resin denture bases.

BackgroundLately, computer-aided design and computer-aided manufacturing (CAD/CAM) has broadly been successfully employed in dentistry. The CAD/CAM systems have recently become commercially available for fabrication of complete dentures, and are considered as an alternative technique to conventionally processed acrylic resin bases. However, they have not yet been fully investigated.ObjectiveThe purpose of this study was to inspect the effects of mechanical polishing and chemical polishing on the surface roughness (Ra) and contact angle (wettability) of heat-cured, auto-cured and CAD/CAM denture base acrylic resins.MethodsThis study was conducted at the Advanced Dental Research Laboratory Center of King Abdulaziz University from March to June 2017. Three denture base materials were selected: heat cure poly-methylmethacrylate resin, thermoplastic (polyamide resin) and (CAD\\CAM) denture base resin. Sixty specimens were prepared and divided into three groups, twenty in each. Each group was divided according to the polishing techniques into (Mech P) and (Chem P), ten specimens in each; surface roughness and wettability were investigated. Data were analyzed by SPSS version 22, using one-way ANOVA and Pearson coefficient.ResultsOne-way analysis of variance (ANOVA) and post hoc tests were used for comparing the surface roughness values between three groups which revealed a statistical significant difference between them (p1<0.001). Heat-cured denture base material of (Group I) in both methods, showed the highest mean surface roughness value (2.44±0.07, 2.72±0.09, Mech P and Chem P respectively); while CAD\\CAM denture base material (group III) showed the least mean values (1.08±0.23, 1.39±0.31, Mech P and Chem P respectively). CAD/CAM showed the least contact angle in both polishing methods, which were statistically significant at 5% level (p=0.034 and p<0.001).ConclusionMechanical polishing produced lower surface roughness of CAD\\CAM denture base resin with superior smooth surface compared to chemical polishing. Mechanical polishing is considered the best effective polishing technique. CAD/CAM denture base material should be considered as the material of choice for complete denture construction in the near future, especially for older dental patients with changed salivary functions, because of its wettability.

Chitosan 2% Effect on Prohibiting the Growth of Candida Albicans on Heatcured Acrylic Resin

Maintaining acrylic denture hygiene is a necessary to prohibit the growth of several oral fungi such as Candida albicans. Candida albicans are the main etiological microorganism of denture stomatitis. One of the ways to clean denture is by immersion on synthetic denture cleaner liquid such as oxygenizing denture cleaners. However, synthetic denture cleaner have several limitation due to its biocompatibility on human body especially oral tissue. Chitosan is a derivate of chitin, a natural compound of sea creature exosceleton. Chitosan have antifungi and antibacterial nature. The objective of this study is to evaluate the antifungi efectifity of chitosan 2% on acrylic heatcured and compare it with oxygenizing denture cleaner. Aquades is used as a control. The sample consists of 15 acrylic heatcured bars (10x10x2 mm) prepared by contamination on Candida albicans suspensions at temperature 37°C for 24 hours and immersed on 3 different treatments wich are chitosan 2%, oxygenizing denture cleanser, and aquades as control and then, the solutions are being vibrate and put into sabouraud dextrose agar medium. The colony of Candida albicans counted manually. Result shows, highest mean of Candida albicans colony on aquades group (365,66 CFU/plate), followed by oxygenizing denture cleanser treatment (178,33 CFU/plate). The smallest number colony of Candida albicans are found at chitosan 2% treatment (45,33 CFU/plate). Statistical analysis using ANOVA one way shows F=9.826 and p=0, this means, there is minimal one pair of groups with very significant differential (p&lt;0,01) which are chitosan 2% and oxygenizing denture cleanser compared to aquades as control. The difference between those two treatments also significant. Conclusions of this study is that chitosan 2% solution have a sifnificant effect on prohibiting the growth of Candida albicans colony on acrylic heatcured denture base materials. The effectivity of this solution is significantly higher than oxygenizing denture cleanser treatment.

Evaluation of Addition of Plant Fixed Oil Extracts (Ginger , Maramia, Eucalyptus) on Some Properties of Heat Cured Denture Base Material

The aim of this study was to evaluate the effect of three types of natural medicinal plants oils on the transverse strength, residual monomer and hardness of polymethylmethacrylate. Materials and methods: Total number of samples of (105) have been prepared in this study. Fifteen samples of heat cured ProBase acrylic resin were prepared without additives ( Control), and (90) samples were pre-pared with additives ( Ginger oil ,Meramia and Eucalyptus oil) in two concentrations (1.5 and 2.5) to evaluate transverse strength, indentation hardness and residual monomer. Results: The results showed a significant difference between control and addition groups in the transverse strength and hardness tests. The addition of oils decreased the transverse strength ,and increased the hardness.There was no significant difference between the residual monomer for control and addition groups, but the control group at the first day showed higher residual monomer release. Conclusion: The addition of eucalyptus , meramia and ginger oils to acrylic resin decreased the transverse strength , increased its hardness and showed no significant difference in residual monomer.

Effect of ageing on the bond strength of a permanent denture soft lining material.

Molloplast-B is a widely used, long-term, heat-cured silicone denture soft lining material. Adhesion failure of this material to poly (methyl methacrylate) denture base material is a problem that is encountered clinically. The purpose of this study was to investigate the effects of long-term immersion in water at 37 +/- 1 degrees C and of accelerated ageing in water at 50 +/- 1 degrees C on the tensile and shear bond strength values of this denture resilient lining material bonded to a heat-cured denture base material. Immersion in water for 1 week at 37 +/- 1 degrees C had no significant effect on the measured bond strength values. Longer immersion of specimens in water at 37 +/- 1 degrees C led to a significant reduction in the measured tensile and shear bond strengths. The present study has demonstrated that the reduction in Molloplast-B bond strength that occurs as a result of long-term ageing in water at 37 +/- 1 degrees C can be achieved in a shorter period of time by ageing the specimens in water at a higher temperature.

低刺激性直接リライニング材で裏装した加熱重合型床用レジンの比例限における曲げ強さ

This study was conducted to investigate the transverse strength at the proportional limit of a heat-cured denture base resin relined with low stimulative direct denture reline materials. The relined specimens with three low stimulative and a conventional self-cured direct denture reline materials were tested with a three-point loading test after 1 day of water immersion. Direction of load on the specimens also was tested. As a result, all relined specimens had significantly lower transverse strength than bulk of a heat-cured denture base material. The transverse strength of specimens relined with low stimulative direct denture reline materials was significantly low as compared with specimens relined with a conventional self-cured type direct denture reline material. There was no significant difference among three low stimulative direct denture reline materials. The direction of load on the specimens did not have an effect on the transverse strength at the proportional limit.

Color stability: Denture base resins processed with the microwave method

Several quick heat-cured denture base resin systems and microwave processing resins have been introduced to provide easier and faster processing. The microwave processing method is the fastest of the heat-cured processing methods. Conventional acrylic resins processed with the microwave method seem to possess adequate physical properties, and one study indicated that a microwave acrylic resin was reasonably color stable under conditions of accelerated aging, although manufacturers do not recommend using them for microwave processing. The purpose of this study was to evaluate the color stability of seven conventional and one microwave heat-cured denture base materials processed with the microwave method. The samples were subjected to conditions of accelerated aging to test for color stability. The color stability was quantitatively measured and color measurements were made before weathering and at 300, 600, and 900 hours. The mean color change for each sample group was statistically analyzed with polynomial regression to determine the pattern of color change over time. The differences in color change for the acrylic resins were significant for all materials, but the color change for Lucitone Hy-pro was not noticeable on visual examination. The results of this study revealed that color changes occurred after accelerated aging in heat-cured denture base resins and Acron GC microwave acrylic resins processed with the microwave method. Hy-pro and TruTone materials exhibited the least color change; Hy-pro material was the most color stable material.