Effect of Tea Tree Oil Addition to Denture Liners Against Candida albicans and Bond Strength to Acrylic Denture Bases.

PURPOSE: To evaluate the effect of adding tea tree oil to denture liners on Candida albicans and bond strength to the acrylic denture base. MATERIALS AND METHODS: Disc-shaped specimens were fabricated from silicone-based resilient liner (Tokuyama, Molloplast), acrylic-based hard liner (GC Reline), and acrylic-based soft liner (Visco-gel). Tea tree oil (TTO) was incorporated into the liners at varying concentrations (0% [control], 2%, 5%, 8%). C albicans were counted by viable colony count, and optical density (OD) was measured with a spectrophotometer. The tensile strength to heat polymerized acrylic denture base was measured in a universal testing machine. The compliance of the data to the distribution of normality was evaluated using the Shapiro Wilk test. Two-way ANOVA, Bonferroni correction, and paired sample t test were performed (α = .05). RESULTS: The addition of TTO into liners provided a significant decrease in the OD values (P < .001). The control groups of the liners presented the highest colony counts, whereas increasing TTO decreased the results (P < .01). According to tensile bond strength test, 8% TTO addition resulted in a significant decrease for Tokuyama (P < .01) and Molloplast liners (P < .05), while 2% TTO resulted in significance for GC Reline (P < .001). CONCLUSIONS: Denture liners containing increasing percentages of TTO presented lower amounts of C albicans colonies and decreased bond strength to the denture bases. When using TTO for its antifungal properties, the amount added should be carefully selected because the tensile bond strength may be affected.

Repair bond strength of different CAD-CAM ceramics after various surface treatments combined with laser irradiation.

The aim of this study was to evaluate the effect of different surface treatments combined with laser irradiation on the shear bond strength of different CAD-CAM ceramics to composite resin. A total of hundred forty-seven ceramic specimens with thicknesses of 2.5 mm were prepared from three different CAD-CAM ceramics (an yttrium oxide partially stabilized tetragonal zirconia polycrystal (Y-TZP); a zirconia-reinforced lithium silicate glass ceramic (ZLS); and a lithium disilicate-strengthened lithium aluminosilicate glass ceramic (LD-LAS)) and subjected to seven groups of treatment (n = 7): (1) control (no treatment), (2) Er:YAG laser irradiation, (3) Nd:YAG laser irradiation, (4) etching with hydrofluoric acid (HFA), (5) Er:YAG + HFA, (6) Nd:YAG + HFA, and (7) sandblasting. After surface treatment procedures, a ceramic primer (Clearfil Ceramic Primer Plus, Kuraray, Japan) was applied to the ceramics. Bonding agent (Single Bond Universal Adhesive, 3 M ESPE, USA) was then applied, and the composite resin (Estelite Sigma Quick, Kuraray, Japan) was layered on the ceramic surfaces. The shear bond strength test was performed using a universal testing machine at a load of 0.5 mm/min. Data were analyzed by 2-way analysis of variance (ANOVA), and the Bonferroni correction was used for pairwise comparisons (α = 0.05). Compared to the bond strength of the control group, irradiation by Er:YAG and Nd:YAG lasers alone improved the bond strength of the composite resin to the Y-TZP (P < 0.001) but did not change the bond strength of composite resin to the ZLS and LD-LAS (P > 0.05). Compared to the bond strength of the control group, etching with HFA alone increased the bond strength of the composite resin to the ZLS and LD-LAS (P < 0.001) but did not affect the bond strength of the composite resin to the Y-TZP (P > 0.05). The highest bond strength of ZLS was obtained using HFA + Er:YAG, and the highest bond strength for LD-LAS was obtained using HFA + Nd:YAG. It was concluded that Er:YAG and Nd:YAG laser treatments presented the highest repair bond strength between the composite resin and Y-TZP ceramics. Er:YAG and Nd:YAG laser treatments in conjuction with HFA presented the highest repair bond strength between the composite resin and the glassy ceramics, ZLS, and LD + LAS.

Effect of cigarette smoke and denture cleansers on the surface properties and color stability of CAD-CAM and conventional denture base resins.

This study aimed to evaluate the hardness, roughness, and color stability of heat- and microwave-polymerized polymethyl methacrylate (PMMA), polyamide, and CAD-CAM PMMA resins when exposed to cigarette smoke (CS) and immersed in a denture cleanser (DC). Specimens of each resins were divided into four subgroups (n=10). The DC and CS+DC specimens were immersed in a DC; the CS and CS+DC specimens were exposed to CS; and the control (C) specimens were kept in distilled water. Hardness, roughness, and color measurements were performed. DC and CS significantly affected the roughness and color of all resins (p<0.05). However, these did not affect the hardness of the CAD-CAM PMMA resin (p>0.05). The CAD-CAM PMMA resin presented the lowest roughness, highest hardness, and lowest ΔE00 values. While the roughness of all resins exposed to CS when immersed in DC decreased, the ΔE00 values of the conventional PMMAs also decreased. Although this decreases were not significant, it may be advisable to use DC for smokers to decrease discoloration and roughness especially for conventional PMMAs resins.

Effect of different cement systems and aging on the bond strength of chairside CAD-CAM ceramics.

STATEMENT OF PROBLEM: The bond strength of different chairside computer-aided design and computer-aided manufacturing (CAD-CAM) restorative materials to dentin with different resin cements needs to be evaluated. PURPOSE: The purpose of this in vitro study was to investigate the effect of 3 different cementation systems after thermal aging on the shear bond strength of different CAD-CAM materials. MATERIAL AND METHODS: The occlusal surfaces of 63 molar teeth of similar size were removed, and 21 zirconia-reinforced lithium disilicate (Vita Suprinity-VS), 21 polymer infiltrated ceramic (Vita Enamic-VE), and 21 resin nanoceramic (GC Cerasmart-GC) rectangular specimens of 2.5 mm in thickness were obtained. The ceramics were cemented using total etch (TE), self-etch (SE), and self-adhesive (SA) cement systems. Half of the specimens were subjected to thermal aging with 5000 cycles. The shear bond strength test of all the specimens was measured. Fractured ceramic surfaces were examined by scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX) analysis. The Shapiro-Wilk test, 3-way analysis of variance (ANOVA), and Fisher Least Significant Difference (LSD) tests were used to analyze the shear bond strength test data (α=.05). RESULTS: The highest bond strength value was found in the nonthermal aged VS-TE and the lowest in the thermal aged VE-TE. Significant interaction was found between TE and SE cemented ceramics (P<.001). For specimens cemented with the SA system, significant interaction was found among ceramics with thermal aged specimens (P<.001). Thermal aging significantly decreased the mean bond strength (P<.05). CONCLUSIONS: Differences in bond strength were observed in chairside CAD-CAM ceramics when cemented with TE, SE, and SA systems. Additionally, thermal aging significantly reduced the bond strength values of all the ceramic materials, regardless of the cementation procedure. Clinicians should consider these variables and choose the most suitable cementation systems for the material used.

Effects of thermal cycling on surface roughness, hardness and flexural strength of polymethylmethacrylate and polyamide denture base resins.

BACKGROUND: The purpose of this study was to evaluate the effects of thermal cycling on the surface roughness, hardness and flexural strength of denture resins. METHODS: Polyamide (PA; Deflex and Valplast) and polymethylmethacrylate (PMMA; QC-20 and Acron MC) denture materials were selected. A total of 180 specimens were fabricated and then divided into 3 groups. The first group (group 1) acted as a control and was not thermocycled. The second group (group 2) was subjected to thermocycling for 10,000 cycles in artificial saliva and 5,000 cycles in distilled water. The last group (group 3) was thermocycled for 20,000 cycles in artificial saliva and 10,000 cycles in distilled water. The surface roughness were measured with a profilometer. The hardness of the resins were measured with a Vickers Hardness Tester using a 100-gf load. The flexural strength test was performed using the universal test machine with a crosshead speed of 5 mm/min. Data were analyzed using statistical software. The results of the measurements in the 3 different tests were analyzed by Kruskal-Wallis test with Bonferroni correction. Multiple comparisons were made by Conover and Wilcoxon tests. RESULTS AND CONCLUSIONS: There was a significant difference between the PMMA and PA groups in terms of surface roughness, hardness and transverse strength before and after thermal cycling (p<0.001). Thermal cycling did not change the surface roughness, hardness and flexural strength values of either the PMMA or PA group (p>0.001).

Effect of surface treatments on the bond strength of veneering ceramic to zirconia.

AIM: The purpose of this study was to evaluate the effect of different surface treatments on the bond strength of veneering ceramic to zirconia. METHODS: Square (15 mm x 10 mm x 2 mm) zirconia specimens (n=18) received one of the following surface treatments: Group 1, sandblasting; Group 2, Clearfil ceramic primer application; Group 3, grinding; Group 4, alloy primer application; and Group 5, RelyX ceramic primer application. The zirconia core specimens were layered with a veneering porcelain (5 mm x 3 mm x 3 mm). Mean shear bond strength values (MPa) were calculated. Data were analyzed with one-way ANOVA and Tukey's post hoc pairwise comparisons (α=0.05). Fractured surfaces of the specimens were examined with scanning electron microscope (SEM). RESULTS: This study showed that bond strengths of the metal primer-treated zirconia specimens (Group 4) were significantly higher than those of the other paired groups. The application of metal primer affected the specimens' failure mode. SEM analysis demonstrated that Group 4 had mainly cohesive fractures, while the other groups showed approximately equal levels of adhesive and mixed fracture types. The mean and SD values for shear bond strengths ranged from 8.90 ± 3.42 MPa (Group 2) to 19.74 ± 4.96 MPa (Group 4). CONCLUSIONS: In conclusion, the application of a metal primer to a zirconia core increased the bond strength of veneering ceramics. The use of chemical agents to improve the strength of the zirconia core's bond to veneering ceramic may have more benefits than the use of mechanical pretreatments.

Comparative effect of different polymerization techniques on residual monomer and hardness properties of PMMA-based denture resins.

PURPOSE: The aim of this study was to compare the residual monomer and microhardness of poly(methyl methacrylate) (PMMA)-based denture resins processed by using autoclave and conventional water bath techniques. METHODS: To determine the amount of residual methyl methacrylate (MMA) monomer, disk-shaped specimens (n=5) were prepared from 3 different acrylic resins (Meliodent, Paladent and Qc-20). Control groups were polymerized in water bath for 30 minutes at 100°C. The study groups were prepared in an autoclave device for 60°C/30 min followed 130°C/10 min and the other group for 60°C/30 min followed by 130°C/20 min. According to standard calibration curves, ultraviolet spectrophotometry at 230 nm was used to determine the residual monomer. For the Vickers hardness measurements, disk-shaped specimens (n=5) were prepared for each test group. Hardness measurements were performed with a Vickers hardness tester under a 4.91-N press load for a 30 seconds, after immersion in distilled water at 37ºC for 48 hours. The data were analyzed by ANOVA and Tukey HSD test (p<0.05). RESULTS: Autoclave polymerization produced a significant decrease in the amount of residual monomers for all resin groups (p<0.05). This procedure also showed a significant increase in hardness for all resin groups (p<0.05). For the 3 resin groups, no significant differences were found between autoclave polymerization for 10 minutes and for 20 minutes (p>0.05). CONCLUSIONS: The autoclave polymerization technique exhibited significantly lower residual monomer content and greater hardness than conventional heat polymerization.

Effects of cigarette smoke and denture cleaners on the surface roughness and color stability of different denture teeth.

STATEMENT OF PROBLEM: Denture teeth have the most effect on the esthetics of complete dentures. However, extrinsic factors can change their roughness and color. PURPOSE: The purpose of this study was to investigate the effects of smoking and denture cleaners on the roughness and color (CIE [Commission International de I'Eclairage] L*a*b*) of denture teeth. MATERIAL AND METHODS: Maxillary central incisors made of acrylic resin, high-strength acrylic resin, and porcelain (Acrylux, SR, Orthosit PE-O, and Enta) were divided into 4 groups (n=10): control, denture cleaner, cigarette smoke, and cigarette smoke and denture cleaner. The dental cleaner group and cigarette smoke and dental cleaner group were immersed in denture cleaner (Protefix; Queisser Pharma) for 15 minutes; the cigarette smoke group and cigarette smoke and dental cleaner group were exposed to smoke from 20 cigarettes for 10 minutes per cigarette. The roughness was measured with a profilometer, and the color was measured with a colorimeter. The CIE L*a*b* values were recorded. The data were analyzed with a 3-way ANOVA and the Fisher least significant difference test (α=.05). RESULTS: The roughness of Acrylux, SR Orthosit PE-O (P<.001), and Enta (P<.01) was significantly higher in the cigarette smoke group and dental cleaner group than in the control group. Immersion in denture cleaner after exposure to cigarette smoke decreased the roughness of Acrylux, SR Orthosit PE-O (P<.001), and Enta (P<.01). The greatest color change (7.94) was observed in Acrylux in the cigarette smoke group, whereas the smallest color change (0.24) was in Enta in the control group. The color change of all of the teeth in the cigarette smoke group decreased after exposure to denture cleaner (P<.05). The L* decreased, and the a* and b* increased after exposure to smoke (P<.05). CONCLUSIONS: Smoking and denture cleaner increased the roughness and discolored the teeth, whereas denture cleaners after exposure to smoke decreased the roughness.

How will surface treatments affect the translucency of porcelain laminate veneers?

PURPOSE: The purpose of this study was to evaluate whether surface treatments affect the translucency of laminate veneers with different shades and thicknesses. MATERIALS AND METHODS: A total of 224 disc-shaped ceramic veneers were prepared from A1, A3, HT (High Translucent) and HO (High Opaque) shades of IPS e.max Press (Ivoclar Vivadent) with 0.5 mm and 1.0 mm thicknesses. The ceramics were divided into four groups for surface treatments. Group C: no surface treatments; Group HF: etched with hydrofluoric acid; Group SB: sandblasted with 30-µm Al2O3 [corrected]; and Group L; irradiated with an Er;YAG laser. A translucent shade of resin cement (Rely X Veneer, 3M ESPE) was chosen for cementation. The color values of the veneers were measured with a colorimeter and translucency parameter (TP) values were calculated. A three-way ANOVA with interactions for TP values was performed and Bonferroni tests were used when appropriate (α=0.05). RESULTS: There were significant interactions between the surface treatments, ceramic shades and thicknesses (P=.001). For the 0.5-mm-thick specimens there were significant differences after the SB and L treatments. There was no significant difference between the HF and C treatments for any shades or thicknesses (P>.05). For the 1-mm-thick ceramics, there was only a significant difference between the L and C treatments for the HT shade ceramics (P=.01). There were also significant differences between the SB and C treatments except not for the HO shades (P=.768). CONCLUSION: The SB and L treatments caused laminate veneers to become more opaque; however, HF treatment did not affect the TP values. When the laminate veneers were thinner, both the shade of the ceramic and the SB and laser treatments had a greater effect on the TP values.

Achieving the desired colour in discoloured teeth, using leucite-based CAD-CAM laminate systems.

OBJECTIVES: To evaluate the cumulative effect of the abutment tooth and resin cement colour on the resultant optical properties of porcelain laminate veneers (PLVs) fabricated with leucite-based CAD/CAM blocks with different shades and thicknesses. METHODS: A total of 224 ceramic specimens were prepared from the IPS Empress CAD with four different shades of HT-A1, LT-A1, MT-A1 and Bl-1. Resin composite discs were prepared with shade A3.5. For the cementation, 4 different shades of light-cure resin cements were chosen. L*, a*, and b* values, as well as the chroma (C) and hue (h) values of each cemented ceramic and the A1 shade table, were recorded. RESULTS: L*, Cab* and hab* values of the cemented ceramics were influenced by ceramic shade, ceramic thickness, cement shade, and interaction terms of the three variables. There were significant differences between the 1-mm-thick ceramic veneers that exhibited higher L* and lower Cab* values compared with veneers that were 0.5mm in thickness. Using the Tr shade cement resulted in lower L* and higher Cab* values for all thicknesses and ceramic shades, whereas the WO shade cement resulted in higher values. CONCLUSIONS: The selected colour of a laminate restoration is significantly affected by the ceramic shade, ceramic thickness and resin cement shade. Using the WO shade resin cement seems to be more effective in masking the discoloured abutment tooth. Clinicians should also select the translucency level of the ceramic block with the shade when a leucite-based CAD/CAM system is chosen to treat a discoloured tooth.

Effect of antiasthmatic medication on the surface roughness and color stability of dental restorative materials.

OBJECTIVE: This study evaluated the effect of antiasthmatic medication on the surface roughness and color stability of dental restorative materials. MATERIALS AND METHODS: A total of 60 disc-shaped specimens were fabricated from glass ionomer (n = 20), composite resin (n = 20) and feldspathic porcelain (n = 20). Each material group was randomly divided into two subgroups (n = 10): (1) control group and (2) test group. Control groups of the specimens were kept in artificial saliva. Test groups were exposed to salbutamol sulfate (Ventolin Nebules) using an inhaler machine. Surface roughness measurements were done using a profilometry and color measurements were done with digital colorimetry at baseline and after inhalation and storing in artificial saliva. A two-way analysis of variance (ANOVA) and post-hoc Fisher's least significant difference test were used to compare the change in surface roughness and color. The confidence level was set at 95%. RESULTS: Inhaler treatment significantly increased the surface roughness and color change of glass ionomer and composite resin materials (p < 0.05), while the surface roughness and color of feldspathic porcelain was not changed after inhaler treatment (p > 0.05). CONCLUSION: The antiasthmatic inhaler medication (salbutamol sulfate) affected the surface roughness and color of composite resin and glass ionomer restorative materials.

Discoloration of provisional restorations after oral rinses.

PURPOSE: Oral rinses are widely used to promote periodontal health with provisional restorations during the interim period. The aim of this study was to compare the discoloration of provisional restoration materials with different oral rinses. MATERIAL AND METHODS: A total of 140 disc-shaped specimens (shade A2) (10 mm x 2 mm) were prepared from one PMMA-based (TemDent Classic(®)) and three different bis-acrylic-based (Protemp II(®), Luxatemp(®) and Fill-In(®)) provisional restoration materials (n=7). The color values (L*, a*, and b*) of each specimen were measured before and after exposure with a colorimeter, and the color changes (∆E) were calculated according to the CIE L*a*b* system. The specimens were immersed in each of the 4 oral rinses (alcohol-containing mouthwash, chlorhexidine, benzydamine HCl, benzydamine HCl and chlorhexidine) twice a day for 2 minutes. After 2 minutes of immersion in the oral rinses, the specimens were immersed in artificial saliva. The specimens were exposed to the oral rinses and the artificial saliva for 3 weeks. Two-way ANOVA, the Bonferroni test and the paired sample t-test were used for statistical analyses (p<0.05). RESULTS: Comparison of the discoloration from the oral rinses after immersion for three weeks revealed no significant differences (p>0.05). The lowest color change was observed in PMMA-based Temdent in all oral rinses (p<0.05). There were no significant differences between the bis-acryl composites after immersion in saliva or the mixture of benzydamine HCl and chlorhexidine and the alcohol-containing mouthwash for 3 weeks (p>0.05). After immersion in chlorhexidine, the color change values of Protemp II and Fill-in showed significant differences (p=0.018). Protemp II also showed less discoloration than the other bis-acryl composites, and this color change was statistically significant (p <0.05). For all oral rinses, the L* value decreased while b* values increased, and this color change was found to be statistically significant (p <0.05). A* values were found to be significantly higher with oral rinses (p<0.05), except Protemp II immersed in benzydamine HCl or alcohol-containing mouthwash. CONCLUSIONS: The type of the oral rinse did not affect the discoloration process. For long-term esthetic results, choosing MMA-based materials for provisional restorations appears to be more effective.

Comparative effects of denture cleansers on physical properties of polyamide and polymethyl methacrylate base polymers.

The purpose of this study was to evaluate the effect of denture cleansers on the surface roughness, hardness and color stability of two polyamides (Valpast, Deflex), a butadiene styrene copolymer PMMA (Rodex), and PMMA polymer as a control group (Paladent). Each material was divided into 5 sub-groups (n=7) as two control and three test groups. Three test groups were immersed for 20 days in commercially available three denture cleansers (CO-Corega, PR-Protefix, VA-Valclean). Two-way analysis of variance and Tukey's post hoc HSD test were used to evaluate surface roughness and hardness data (α=0.05). ΔE, ΔL*, Δa*and Δb* mean values were used for ANOVA, Tamhane test was used as post hoc. Polyamides showed low hardness and high roughness before and after immersion. A significant decrease in hardness was observed for all resins except Rodex after immersion (p<0.05). The denture cleansers changed the roughness, hardness and color of some resins.

Gender difference in prevalence of signs and symptoms of temporomandibular joint disorders: a retrospective study on 243 consecutive patients.

BACKGROUND: This study evaluated the prevalence of the signs and symptoms of temporomandibular joint disorder (TMD) among patients with TMD symptoms. METHODS: Between September 2011 and December 2011, 243 consecutive patients (171 females, 72 males, mean age 41 years) who were referred to the Department of Prosthodontics, Faculty of Dentistry, Karadeniz Technical University, Trabzon were examined physically and completed a questionnaire regarding age, gender, social status, general health, antidepressant drug usage, dental status, limited mouth opening, temporomandibular joint (TMJ) sounds, and parafunctions (bruxism, clenching). The data were analyzed using the chi-square test and binary logistic regression model (alpha = 0.05). RESULTS: With a frequency of 92%, pain in the temporal muscle was the most common symptom, followed by pain during mouth opening (89%) in both genders. TMJ pain at rest, pain in the masseter muscle, clicking, grinding, and anti-depressant use were significantly more frequent in females than males. Age (p=0.006; odds ratio 0.954; 95% CI 0.922-0.987) and missing teeth (p=0.003; odds ratio 3.753; 95% CI 1.589-8.863) had significant effects on the prevalence of TMD. CONCLUSION: Females had TMD signs and symptoms more frequently than males in the study population. The most common problem in both genders was pain.