Illuminant metameric effects on interbrand and intrabrand color differences of direct composite resins.

STATEMENT OF PROBLEM: Information on the illuminant metameric effects on the intrabrand and interbrand differences in color of direct composite resins is lacking. PURPOSE: The purpose of this in vitro study was to evaluate the effects of different illuminations on the color differences of the same or different brands of composite resins. MATERIAL AND METHODS: Sixty-four disks were prepared from 8 different direct dental composite resins of A3 shade, and, after polymerization and hydration for 48 hours, their color coordinates were measured in the Commission Internationale de I'Eclairage (CIE) L∗a∗b∗ color space with a portable colorimeter on a black and white background under D65 (daylight), F2 (cool white fluorescence), and A (incandescence) illuminations. Translucency parameters (TP) and fluorescence intensities (FI) of the brands were also measured to assist in the interpretation of brand behavior under the illuminations. The Kruskal-Wallis and Friedman nonparametric tests with post hoc multiple comparisons tests were applied to analyze the data for differences within and between brands under all illuminations (α=.05), while regression analysis was used to estimate the relationship between D65 and F2 or A illumination data. RESULTS: Statistical analysis showed significant differences among brands (P<.05) for all color coordinates under all illuminations, with a strong linear relationship between them (R2=0.72-0.97). Intrabrand differences were significantly different across brands (P<.05) and ranged from 0.06 to 3.1 across illuminations in ΔE∗ab units (0.05 to 2.4 in ΔΕ00 units). Interbrand differences were also significantly different (P<.05), with a range of 0.15 to 8.7 ΔE∗ab units or 0.14 to 5.7 ΔΕ00 units. CONCLUSIONS: Primary color coordinates of composite resins were affected by A or F2 illumination and were strongly associated with D65 values. Redder or yellower composite resins were affected more under A or F2 illumination. Intrabrand differences, although small, may contribute to clinical mismatches under A or F2 illuminations. Clinicians should be aware that certain brand pairs may present acceptable differences under D65 illumination but could become unacceptable under A or F2 illumination.

Efficacy of non-hydrogen peroxide mouthrinses on tooth whitening: An in vitro study.

OBJECTIVES: To evaluate the tooth whitening efficacy of non-hydrogen peroxide containing mouthrinses. METHODS: Forty incisors were randomly assigned into four groups. Four whitening mouthrinses, Oral-B 3D White Luxe/Procter & Gamble (WL), Listerine Advanced White/Johnson & Johnson (AW), Colgate Max White/Colgate (MW), and iWhite Whitening Mouthwash/Sylphar (iW), were used over a four-week period. Color changes of L*, a*, b*, ΔE*ab , and ΔE00 , were recorded by a digital spectrophotometer (Spectroshade Micro/Mht), at baseline and intermediate week-intervals. Data were statistically analyzed using repeated measures ANOVA at α = 0.05. RESULTS: The first-week mean change of L* was 0.76 and significantly different from the baseline for all solutions, without any further changes. Correspondingly, a* decreased by -0.36, while b* increased by 0.48, contributing to a color change of 1.15 ΔE*ab or 0.91 ΔE00 . No differences were found among the solutions in respect to color-parameter changes (p > 0.05). Differences among time intervals were significant (p < 0.05) and mainly observed between the baseline and the following week-measurements. There was no statistically significant time-solution interaction (p > 0.05). CONCLUSIONS: Non-hydrogen peroxide whitening mouthrinses, slightly contribute to tooth whitening, by removing superficial staining, without any further tooth bleaching effect. CLINICAL SIGNIFICANCE: Non-hydrogen peroxide containing whitening mouthrinses, despite having a quick initial action, reach their ceiling relatively soon. Their effectiveness is barely perceptible and definitely inferior to other professional tooth bleaching methods. Thus, they can only be considered as a supplementary way of keeping teeth whiter, mainly by preventing recurrent tooth discoloration.

Removal of denture adhesives from PMMA and Polyamide denture base materials.

OBJECTIVE: Denture adhesives need complete removal due to their frequent replacement. Our study investigates the removal of denture adhesives from denture base materials, using different methods. METHODOLOGY: PMMA and Polyamide denture base materials were used to fabricate 120 samples (15×15×1.5mm). One side of the samples was left as processed and the other polished with a usual procedure, hydrated for 24 h, dried, and weighted. They received 0.2 g of three adhesive creams on their unpolished surface (Corega, Olivafix, Fittydent), pressed on polysulfide material, stored under 37°C and 95% rel. humidity for 1 h and 60 of them, following their separation from polysulfide base, brushed under running water, whereas the rest inserted in a cleanser bath (Fittydent Super) for 5 min. The samples were dried and inserted in the oven (37°C) for additional 10 min and weighted again. Roughness tests of denture materials and light microscopy of adhesives creams were also used to evaluate the materials. Time lapse images of spayed with water adhesives on PMMA base were also taken to evaluate the volumetric changes of adhesives. Weight data before and after adhesive removal, indicating the amount of remaining adhesive, were statistically analyzed using Welch's ANOVA and Games-Howell multiple comparisons tests at α=0.05 level of significance. RESULTS: Roughness of Polyamide was higher than PMMA and Fittydent showed greater volumetric changes than the others. Significant differences (p<0.05), were found between PMMA and Polyamide bases, between Olivafix and Fittydent adhesives, and between brushing and cleansing methods but only for PMMA-Olivafix combination. CONCLUSIONS: Adhesives showed a stronger adherence to PMMA surface, and Fittydent was the most difficult to be removed. Removal methods were not effective for all adhesives or denture base materials. These indicate that removal methods, adhesive type and denture base material are all playing a significant role in the removal of adhesives from denture surfaces.

Removal of denture adhesives from PMMA and Polyamide denture base materials

Abstract Denture adhesives need complete removal due to their frequent replacement. Objective Our study investigates the removal of denture adhesives from denture base materials, using different methods. Methodology PMMA and Polyamide denture base materials were used to fabricate 120 samples (15×15×1.5mm). One side of the samples was left as processed and the other polished with a usual procedure, hydrated for 24 h, dried, and weighted. They received 0.2 g of three adhesive creams on their unpolished surface (Corega, Olivafix, Fittydent), pressed on polysulfide material, stored under 37°C and 95% rel. humidity for 1 h and 60 of them, following their separation from polysulfide base, brushed under running water, whereas the rest inserted in a cleanser bath (Fittydent Super) for 5 min. The samples were dried and inserted in the oven (37°C) for additional 10 min and weighted again. Roughness tests of denture materials and light microscopy of adhesives creams were also used to evaluate the materials. Time lapse images of spayed with water adhesives on PMMA base were also taken to evaluate the volumetric changes of adhesives. Weight data before and after adhesive removal, indicating the amount of remaining adhesive, were statistically analyzed using Welch's ANOVA and Games-Howell multiple comparisons tests at α=0.05 level of significance. Results Roughness of Polyamide was higher than PMMA and Fittydent showed greater volumetric changes than the others. Significant differences (p<0.05), were found between PMMA and Polyamide bases, between Olivafix and Fittydent adhesives, and between brushing and cleansing methods but only for PMMA-Olivafix combination. Conclusions Adhesives showed a stronger adherence to PMMA surface, and Fittydent was the most difficult to be removed. Removal methods were not effective for all adhesives or denture base materials. These indicate that removal methods, adhesive type and denture base material are all playing a significant role in the removal of adhesives from denture surfaces.

Intra- and inter-brand color differences of denture teeth under different illuminations.

Debonding, staining and wear are usually the reasons for denture teeth replacement by new ones from same or different brands. Objective This study investigates the possible differences in color of denture teeth of the same or different brands under different illuminations, since their metameric behavior in color under specific illumination may become unacceptable. Methodology For the purpose of this study, 10 denture teeth (#11), shade A3, of 4 different brands were selected (Creopal/KlemaDental Pro, Executive/DeguDent, Cosmo HXL/DeguDent, Ivostar/Ivoclar-Vivadent). Teeth stabilized in white silicone mold and the CIELAB color coordinates of their labial surface under 3 different illumination lights (D65, F2, A) were recorded, using a portable colorimeter (FRU/WR-18, Wave Inc). ΔE*ab values of all possible pairs of teeth of the same brand (n=45) or pair combinations of different brands (n=100) under each illumination light, in a dry and wet state were calculated. Data were analyzed statistically using 3-way ANOVA, Friedman's and Wilcoxon's tests at a significance level of α=0.05. Results The results showed that brand type affected significantly L*, a* and b* coordinates (p<0.0001), illumination a* and b* coordinates (p<0.0001), but none of them was affected by the hydration state of teeth (p>0.05). Intra-brand color differences ranged between 0.21-0.78ΔΕ* units with significant differences among brands (p<0.0001), among illumination lights (p<0.0001) and between hydration states (p=0.0001). Inter-brand differences ranged between 2.29-6.29ΔΕ* units with significant differences among pairs of brands (p<0.0001), illumination lights (p<0.0001) and hydration states (p<0.0001). Conclusions Differences were found between and within brands under D65 illumination which increased under F2 or A illumination affected by brand type and hydration status. Executive was the most stable brand than the others under different illuminations or wet states and for this reason its difference from other brands is the lowest. In clinical practice, there should be no blending of teeth of different brands but if we must, we should select those that are more stable under different illuminations.

Influence of lightness of teeth and lip position of a posed smile on the perception of its attractiveness.

BACKGROUND: The lightness of teeth and the distances of the upper and lower lip from the maxillary cervical and incisal lines are factors that correlate with smile attractiveness. PURPOSE: This study investigates the degree of association of the above factors with smile attractiveness and evaluates the possible effect of evaluators' gender, age, occupation, and education level on the perception of smile attractiveness. MATERIALS AND METHODS: An almost perfect smile of an adult Caucasian female was altered to create various smile images with differences in lightness of teeth and upper and lower lip positions. The images were randomly assembled in three slides of four, seven, and five images each and presented to 130 participants to evaluate the most attractive smile (MAS) and the least attractive smile (LAS). Data collected were analyzed for differences between gender, age, occupation, and education level as regards the evaluation of the MAS and LAS using the chi-square test with a significance level of α = 0.05. RESULTS: Statistical analysis showed that the smile images in L1 and L2 were equally considered to be the most attractive smiles. The chi-square test indicated no differences between all groups (P > 0.05). Percentages for the most attractive smiles for the lower lip positions were almost equal for most positions of the upper lip, with differences only between age groups (P > 0.05). The least attractive smiles were those with the upper lip position at 3 mm above the cervical line, with differences only between occupation groups (P < 0.001). CONCLUSION: The results of this study indicate that lightness of teeth positively affects smile attractiveness. Lower lip positions with a distance of 0 to 1 mm from the maxillary incisal line are considered more attractive. Upper lip distances were strongly associated with smile attractiveness. Gender, occupation, and education level did not differently affect the perception of attractiveness due to lower lip positions, but age did.

Color changes of polyetheretherketone (PEEK) and polyoxymethelene (POM) denture resins on single and combined staining/cleansing action by CIELab and CIEDE2000 formulas.

PURPOSE: The purpose of study was to investigate the long-term effect of staining and/or cleansing solutions on the color stability of two non-metal removable partial denture materials. METHODS: One hundred disks (25×3mm) of polyoxymethylene (POM) and polyetheretherketone (PEEK) were immersed in water, wine, coffee, cleanser and combo bath, simulating normal daily use. Color parameters in the CIELAB system was measured every 30 cycles up to 240 using a contact colorimeter and color differences estimated using ΔEab and ΔE00 formulas. Two-way repeated measures ANOVAs and regression analyses were performed at α=0.05. RESULTS: Regression analysis indicated a strong R2 between color changes and number of cycles, for both materials. Tests of within-subjects effects for the ΔEab revealed significant differences among cycles and between the materials in the wine and coffee baths (p<0.001). Significant materialXcycles interactions were also recorded with all staining baths. ΔE00 values were lower than ΔEab up to 63.6%. Tests within and between-subjects effects for the ΔE00 gave similar but not the same with ΔEab results. CONCLUSIONS: ΔE00 found to correlate well with ΔEab. Long term exposure of both materials showed a progressive discoloration in all except control baths. POM discolored more than PEEK in coffee, and combo baths but not in cleanser. Discoloration was smaller in combo bath (where a cleanser was also used) indicating the effectiveness of a cleanser to prevent long term discoloration of both materials.

Intra- and inter-brand color differences of denture teeth under different illuminations

Abstract Debonding, staining and wear are usually the reasons for denture teeth replacement by new ones from same or different brands. Objective This study investigates the possible differences in color of denture teeth of the same or different brands under different illuminations, since their metameric behavior in color under specific illumination may become unacceptable. Methodology For the purpose of this study, 10 denture teeth (#11), shade A3, of 4 different brands were selected (Creopal/KlemaDental Pro, Executive/DeguDent, Cosmo HXL/DeguDent, Ivostar/Ivoclar-Vivadent). Teeth stabilized in white silicone mold and the CIELAB color coordinates of their labial surface under 3 different illumination lights (D65, F2, A) were recorded, using a portable colorimeter (FRU/WR-18, Wave Inc). ΔE*ab values of all possible pairs of teeth of the same brand (n=45) or pair combinations of different brands (n=100) under each illumination light, in a dry and wet state were calculated. Data were analyzed statistically using 3-way ANOVA, Friedman's and Wilcoxon's tests at a significance level of α=0.05. Results The results showed that brand type affected significantly L*, a* and b* coordinates (p<0.0001), illumination a* and b* coordinates (p<0.0001), but none of them was affected by the hydration state of teeth (p>0.05). Intra-brand color differences ranged between 0.21-0.78ΔΕ* units with significant differences among brands (p<0.0001), among illumination lights (p<0.0001) and between hydration states (p=0.0001). Inter-brand differences ranged between 2.29-6.29ΔΕ* units with significant differences among pairs of brands (p<0.0001), illumination lights (p<0.0001) and hydration states (p<0.0001). Conclusions Differences were found between and within brands under D65 illumination which increased under F2 or A illumination affected by brand type and hydration status. Executive was the most stable brand than the others under different illuminations or wet states and for this reason its difference from other brands is the lowest. In clinical practice, there should be no blending of teeth of different brands but if we must, we should select those that are more stable under different illuminations

Evaluation of a Realistic Cleansing Protocol for Preventing Discoloration of Denture Resins.

PURPOSE: To evaluate the efficacy of a realistic staining/cleansing protocol for long-term prevention of discoloration of denture base resins. MATERIALS AND METHODS: Sixty discs (20 × 2.5 mm) of auto- and heat-polymerizing denture acrylic resins were fabricated following manufacturer's instructions, polished on one side and stored in water (37°C) for 24 hours before they were assigned randomly into 6 groups (3 for each material, n = 10) to receive 220 cycles of three immersion protocols. Group A was immersed in the following baths: (1) filtered coffee at 45°C for 2 minutes, (2) tap water at 24°C for 20 seconds, (3) as bath 1, (4) as bath 2, (5) Corega Extradent cleansing solution at 45°C for 3 minutes, and (6) water at 24°C for 20 seconds. Group B was immersed in the four first baths of group A (without cleansing action) and group C in bath 1 for the cumulative action of 20 cycles (80 minutes in 45°C coffee) and bath 2 for 40 seconds. A noncontact optical interferometric profilometer was used for qualitative evaluation of the specimens and a contact colorimeter to estimate color change values (ΔΕ*ab) at baseline and every 20 cycles in the baths for a total of 220 cycles. Data were statistically analyzed using a 2-way-repeated measures ANOVA with Bonferoni multiple comparisons and trend analysis at α = 0.05 level of significance. RESULTS: Data indicated changes in color from 1.7 to 14.2 ΔΕ*ab units. The highest values were related to the number of cycles and group B immersion protocol. Significant differences were found among immersion protocols (p < 0.001) and immersion cycles (p < 0.001) with a significant interaction between protocols and cycles (p < 0.001) but not between denture resins (p = 0.991). CONCLUSION: The evaluated protocol A was found effective in preventing color changes in both denture resins even after a long period of action. Protocol C had a much lower staining effect on both resins than protocol B and behaved similarly to protocol A until 140 to 160 cycles. Therefore, it is probably not appropriate for use in short-term color stability experiments.

Perceptibility and acceptability thresholds of simulated facial skin color differences.

PURPOSE: This study investigates the perceptibility and acceptability thresholds (PT, AT) of observers for L*, a* and b* facial skin differences, very important for the fabrication of a maxillofacial prosthesis. METHODS: One image (10×13.3cm/300dpi), simulating standard facial skin color, and 27 smaller images (4.9×6.0cm/300dpi), simulating shades with different RGB values from the standard were made, using Adobe-Photoshop CS3. The RGB values, were based on 9 stepped increases in L*, a* and b*. Images were shown in the middle of a computer screen with the standard image in the background. 90 persons with normal color vision and optical acuity were selected and instructed to evaluate 81 (27×3) randomly shown images for a perceptible or an acceptable (48h later) mismatch, between central and background image. Using best fitting regression curves 50 % PT and 50 % AT for all parameters were estimated along with their 95 %CI. RESULTS: Observers' reliability found high (0.807-0.945) while the cubic and exponential were the best fitted curves to the data. Overall 50 % ATs were smaller than 50 % PTs (p<0.01) and overall ΔL* parameter showed the lowest thresholds (0.119PT/0.864AT), significantly smaller (p<0.05) than Δa* (0.993PT/2.037AT), Δb* (1.147PT/2.517AT), and ΔEab*(1.497PT/1.808AT). No differences were found between sex or age groups in 50 % ATs for Δa* and Δb* parameters, but 50 % PT for Δa* was smaller in females and in older people with the opposite for Δb*. CONCLUSIONS: Changes in L* were more perceptible and less acceptable than changes in a* and b*. For this reason ΔL* parameter needs attention equally to ΔE*ab when fabricating a facial prosthesis.

Long-term microwaving of denture base materials: effects on dimensional, color and translucency stability.

INTRODUCTION: While the combined effect of microwave irradiation with cleansing solutions on denture base materials has been investigated, the effects of only using microwave irradiation and, more importantly, in a long-term basis, was not studied yet. OBJECTIVE: The purpose of this study was to evaluate the effect of a long-term repeated microwaving on the dimensional, color and translucency stability of acrylic and polyamide denture base materials. MATERIAL AND METHODS: Thirty two specimens (32 mm x 10 mm x 2.5 mm) from polyamide (Valplast) and PMMA (Vertex Rapid Simplified) denture base materials were made. Eight specimens from each material were immersed in distilled water (control) and 8 were subjected to microwave exposure at 450 W for 3 minutes for a period simulating 224 days of daily disinfection. Linear dimension, color change (ΔE*) and translucency parameter (TP) were measured at baseline and after certain intervals up to 224 cycles of immersion, using a digital calliper and a portable colorimeter. The results were analysed using two-way repeated measures ANOVA to estimate possible differences among predetermined cycles and material type. Regression analysis was also performed to estimate the trend of changes with time. Statistical evaluations performed at a significance level of 5%. RESULTS: Data analysis showed significant changes in length at baseline with an increasing number of cycles (p<0.05) and a significant interaction of cycle-material (p<0.001). The ΔΕ* parameter was significantly higher with a higher number of cycles (p<0.001), but it did not vary between materials (p>0.05). TP decreased similarly in both materials following microwave action but in a significantly higher level for Valplast (p<0.001). CONCLUSIONS: The results indicated that long-term repeated microwaving affects linear dimensional, color and translucency changes of both materials. Differences between PMMA and polyamide material were noted only in dimension and translucency changes.

Long-term microwaving of denture base materials: effects on dimensional, color and translucency stability

Abstract While the combined effect of microwave irradiation with cleansing solutions on denture base materials has been investigated, the effects of only using microwave irradiation and, more importantly, in a long-term basis, was not studied yet. Objective The purpose of this study was to evaluate the effect of a long-term repeated microwaving on the dimensional, color and translucency stability of acrylic and polyamide denture base materials. Material and Methods Thirty two specimens (32 mm x 10 mm x 2.5 mm) from polyamide (Valplast) and PMMA (Vertex Rapid Simplified) denture base materials were made. Eight specimens from each material were immersed in distilled water (control) and 8 were subjected to microwave exposure at 450 W for 3 minutes for a period simulating 224 days of daily disinfection. Linear dimension, color change (ΔE*) and translucency parameter (TP) were measured at baseline and after certain intervals up to 224 cycles of immersion, using a digital calliper and a portable colorimeter. The results were analysed using two-way repeated measures ANOVA to estimate possible differences among predetermined cycles and material type. Regression analysis was also performed to estimate the trend of changes with time. Statistical evaluations performed at a significance level of 5%. Results Data analysis showed significant changes in length at baseline with an increasing number of cycles (p<0.05) and a significant interaction of cycle-material (p<0.001). The ΔΕ* parameter was significantly higher with a higher number of cycles (p<0.001), but it did not vary between materials (p>0.05). TP decreased similarly in both materials following microwave action but in a significantly higher level for Valplast (p<0.001). Conclusions The results indicated that long-term repeated microwaving affects linear dimensional, color and translucency changes of both materials. Differences between PMMA and polyamide material were noted only in dimension and translucency changes.

Evidence provided for the use of oscillating instruments in restorative dentistry: A systematic review.

Oscillating diamond instruments are considered gentle sources for the removal of demineralized tooth hard tissues and the preparation of cavity angles and margins needed in minimally invasive dentistry. However, there is a question if literature provides enough evidence for their efficacy in restorative dentistry procedures. A literature search until May 2016 was conducted, using PubMed, Scopus, and The Cochrane Central Register of Controlled Trials databases. The quality of the studies was assessed using the recommendation of the Oxford Centre for Evidence-based Medicine. Fifty-five studies were finally included in the study. Of which, 78.2% of them were laboratory studies and only 21.8% were clinical studies. The strength of recommendation was 5 for most of them and D their grade of evidence. Bond strength of adhesives on surfaces prepared with these instruments, effective caries removal and cutting characteristics of the oscillating instruments were the main targets of the studies. Conventional diamond, steel, and chemical vapor deposition diamond tips and systems based on abrasive slurry were the oscillating tips, used in different studies. The strength of recommendation and grade of evidence of the studies were low. Although these devices seem to be useful for many clinical situations, there is a need for more well-structured evidence-based studies with more widely accepted procedures and common devices, to have more meaningful results and conclusions of higher strength.

Attitudes of dentists toward denture adhesives: A questionnaire survey in Greece.

STATEMENT OF PROBLEM: The attitudes of dental professionals toward denture adhesives (DAs) require further investigation. PURPOSE: The purpose of this survey was to assess the attitudes of dentists in Greece toward DAs and the possible effects of sex, age, training, and awareness level on these attitudes. MATERIAL AND METHODS: An 18-item questionnaire in the Greek language concerning the use of DAs by dentists in the metropolitan area of Athens, Greece was distributed on line. Its URL address was emailed to 793 randomly chosen dentists in the area, 438 of whom filled out and submitted a valid questionnaire (55.2% response rate). Data for each item were statistically analyzed for their associations with sex, age, training, and awareness level by the chi-square test for independence (α=.05). RESULTS: The results showed that 61.5% of general practitioners and 49% of specialist prosthodontists recommend the use of DAs. Their continuous use was recommended most frequently (46.9%), mainly in the cream form (93.8%). Their use was recommended not only for patients wearing older dentures (60.2%) but also for patients with newly fabricated ones (61.9%) to assist their adaptation to dentures (42.2%). Associations were found between a few only items and sex (Q07, Q11a,b), age (Q13), training (Q11q,b), and awareness level (Q11a,b,d,e) (P<.05). CONCLUSIONS: This survey shows that in the metropolitan area of Athens, Greece, a significant proportion of dentists (60.3%) recommend the use of DAs and do so more often as a continuous regimen for both existing and new denture wearers. Sex, age, training, and awareness level proved to be factors affecting only a few dentists' attitudes.

Short-Term Assessment of the OHIP-14 Scale on Denture Wearers Using Adhesives.

PURPOSE: The purpose of this study was to assess differences of the Oral Health Implant Profile-14 (OHIP-14) scale over a month and determine association with gender, supporting tissues (KIS), and denture base (KID) among patients wearing complete dentures using denture adhesives. MATERIALS AND METHODS: Sixteen denture wearers, candidates for a new set of complete dentures, were selected. OHIP-14 scores were recorded at the beginning of the study, 6 weeks after fitting of the new set (T0 ), 15 days (T1 ), and finally 30 days (T2 ) after daily use of a denture adhesive as instructed. The KIS and KID were clinically examined and rated according to the Kapur Index. Statistical analyses were based on repeated-measures ANOVA, Mann-Whitney test, regression analysis, and Friedman test at a = 0.05. RESULTS: The OHIP-14 scale was found to have a high reliability (alpha = 0.847) and a high test-retest consistency (ICC = 0.889); however, domain 1 had the lowest item-total correlation (rho = 0.144) and item 7 a negative one (rho = -0.414). Trend analysis indicated a significant negative linear trend over time (slope = -3.156, p = 0.002), while repeated-measures ANOVA showed differences in OHIP-14 between T2 and T1 (p = 0.003) or T0 (p = 0.005) intervals. OHIP-14 groups were found to be positively associated with KIS (p = 0.010) and negatively with KID (p = 0.047) groups, but not with gender (p = 0.272). CONCLUSIONS: The study shows that OHIP-14 has a high internal reliability and consistency when applied to new denture wearers, and its score decreases if denture adhesives are used for at least 15 days. Low KIS and high KID contributes to this trend. Some OHIP-14 items are more associated than others with the total score trend over time.

Flexible Removable Partial Denture Prosthesis: A Survey of Dentists' Attitudes and Knowledge in Greece and Croatia.

PURPOSE: The aim of this study was to investigate through a questionnaire the knowledge, attitudes and possible differences in the use of flexible RPDPs among dentists in Greece and Croatia. MATERIAL AND METHODS: A questionnaire of 16 questions was originally created in English, translated into Greek and Croatian language following a two way translation and tested for apprehension, precision, clarity and homogeneity by a number of native English speaking Greek and Croatian dentists. Following the necessary corrections, the questionnaires replicated in two online surveys and their addresses with an informed consent were sent by emails to nearly 4000 dentists in each country to participate. Collected data were analyzed by chi-square tests at a= .05 level of significance. RESULTS: 378 dentists from Greece and 304 from Croatia participated in the study. 137(36.2%) dentists from Greece and 56(18.4%) from Croatia provided flexible RPDPs to their patients. Statistical analysis for all providers indicated no significant difference between genders (P>.05), significant differences between age groups (P<.01), years of practice (P<.05), specialization (P <.001), and instruction on flexible prostheses (P <.001). The analysis between the two countries showed differences for gender and age groups (P<.01) but no differences between experienced, specialized or instructed groups (P >.05). CONCLUSION: The survey indicated differences between the two countries in the percentages of dentists using, selecting and providing RPDPs for their patients. Practitioners' age, years in practice and instruction were associated with the provision of the prostheses, while comfort, esthetics and cost were the reasons for deciding to use the flexible RPDPs. CONCLUSION: Although dentists are not educated in their schools about flexible RPDPs, almost a third of them offer this treatment to their patients. Long term success of these devices depends on clinical education, more experience and definitely more research.

Effects of cleansing methods on 3-D surface roughness, gloss and color of a polyamide denture base material.

OBJECTIVE: The purpose of this study was to determine the effects of two denture cleansing methods on 3-D surface roughness, gloss and color of denture base materials. MATERIALS AND METHODS: Thirty disks from nylon (Valplast) and 30 from heat-polymerized acrylic denture base material (Paladon 65) were made and 10 of each material were immersed in water (control), Val-Clean (peroxide cleanser) and Corega Extradent (peroxide cleanser) plus microwaving for a period simulating 30 days of daily cleansing. 3-D surface roughness, gloss and color parameters were measured before and after cleansing using an interferometric profilometer, a gloss meter and a colorimeter. The results were statistically analysed by regression, paired-t, Mann-Whitney and Kruskal-Wallis tests at α = 0.05 level of significance. RESULTS: The results showed significant differences at baseline in L* and b* parameters between materials (p < 0.01), with a significantly lower gloss (p < 0.05) and higher roughness (p < 0.05) for Valplast. After cleansing, Δϵ* was significantly greater in Valplast than Paladon 65 (p < 0.05). Gloss of both materials decreased significantly within the Corega Extradent plus microwave solution (p < 0.05), while roughness increased significantly only for Paladon 65 (p < 0.05). CONCLUSIONS: Valplast was found to have a significantly lower gloss and a higher roughness than Paladon 65 before cleansing. After cleansing, ΔE* increased more in Valplast than in Paladon 65, gloss of both materials decreased and roughness only of Paladon 65 increased within the Corega extradent plus microwaving method.

Volume fraction and location of voids and gaps in ultraconservative restorations by X-ray computed micro-tomography.

BACKGROUND: Volume fraction (Vf) and location of internal voids and gaps in relation to material type and cavity dimensions in ultraconservative restorations were investigated in this study. MATERIALS AND METHODS: Forty-eight round cavities of 1.3 mm mean diameter and 2.6 mm mean depth were made on buccal and lingual surfaces of recently extracted human teeth. These were filled and thermocycled with two low viscosity composites (AeliteFlo LV [AF], PermaFlo [PF]), one high viscosity composite (Aelite aesthetic enamel [AA]) and one glass-ionomer (GCFuji IX GP). X-ray microtomography, following a specific procedure, was applied to all cavities before and after their restoration, using SkyScan-1072 microtomographer. Vf percent (Vf%) and location of voids and gaps were recorded and analysed statistically at a = 0.05. Kruskal-Wallis nonparametric analysis of variance, post-hoc analysis, Mann-Whitney test, Spearman's correlation analysis were used to analyze data. RESULTS: Cavities filled with AF and PF showed significantly lower Vf % of voids and gaps than all other restorations (P < 0.05). Only for the cavities filled with AA, cavity width and depth was significantly correlated with Vf % (P < 0.05). 50-75% of the filled cavities contained internal voids regardless of the restorative material (P > 0.05). The proportion of cavities with gaps at the bottom and side walls was lower in those filled with AF and PF (P < 0.05). CONCLUSION: Cavities filled with low viscosity composites presented the lowest amount of internal voids and gaps. Glass-ionomer and high viscosity composite restorative materials showed the highest amount of interfacial gaps. Only in the high viscosity composite restorations the amount of voids and gaps correlated with the cavity depth, width and volume.

Color changes in staining solutions of four light-cured indirect resin composites.

The purpose of this study was to investigate the effect of different staining solutions on the color coordinates of indirect light-cured resin composites. 112 discs were made using four indirect composites, Signum+/Haraeus-Kulzer, Sinfony/3M-Espe, GC Gradia/GC, Ena HRi/Micerium, and divided into four groups which immersed in tea, coffee, chocolate and distilled water, at 37 °C, for 4 weeks. The color, before and after immersion for 1, 2, 3 and 4 weeks, was measured according to CIELAB system and ΔL*, Δa*, Δb* and ΔE* values were calculated for all immersion periods. The effect of time, solution and material on primary and secondary color coordinates was estimated using two-way repeated ANOVAs and pairwise comparisons, at a = 0.05. The results showed that coffee strongly affected all the materials (p < 0.05), followed by tea and chocolate. Sinfony presented the highest color change (p < 0.05), due to changes in b* and L* coordinates. Color coordinates were affected differently by material type and solution. In conclusion, this study showed that the color of indirect resin composites was affected by all three examined factors (immersion time, staining solution and material type), in a clinically appreciable level (ΔΕ* > 2.7 U) even from the first week, and in an unacceptable level (ΔΕ* > 5.5 U) in the second, third and fourth week, depending on the staining solution and the material.

Effect of adaptation time on the occlusal force at denture dislodgement with or without denture adhesive.

STATEMENT OF PROBLEM: The effect of denture adhesives on the occlusal forces at the dislodgement (OFD) of new complete dentures during the adaptation period has not been previously studied. PURPOSE: The purpose of this study was to investigate the OFD of dentures after their insertion and 3 months later, with or without denture adhesives. MATERIAL AND METHODS: Thirteen volunteers with edentulism were enrolled in the study. Each participant had new complete maxillary and mandibular dentures. The occlusal forces (N) at denture dislodgement were assessed with or without 2 adhesives by using an electronic gnathodynamometer in the incisal and premolar regions on the existing denture, the new denture immediately after fitting, 45 days later, and 90 days later. The statistical analysis included the Wilcoxon and Kruskal-Wallis tests, repeated measures ANOVA, and the Pearson coefficient at α=.05. RESULTS: Repeated measures ANOVA for new dentures showed that the OFD in the incisal or premolar region were significantly different between adaptation periods (P<.05) but not between adhesives. OFDs of dentures with and without adhesives correlated highly at all adaptation periods (0.912 to 0.995). CONCLUSIONS: The adaptation period does affect the OFD of new dentures, but the 2 adhesives were found to have the same effect on the OFD.