Effectiveness of prosthetic rehabilitation and quality of life of older edentulous head and neck cancer survivors following resection of the maxilla: a cross-sectional study.

PURPOSE: To evaluate the effectiveness of prosthetic rehabilitation, as well as the quality of life (QOL) of older edentulous maxillectomy patients. METHODS: Effectiveness of the complete denture obturator prosthesis and QOL of N = 44 older edentulous patients who had resection of the maxilla and were restored with a definitive prosthesis that was in use for a minimum of 1 year was assessed using three instruments: European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Core Questionnaire (QLQ-C30), Head and Neck Cancer Module (QLQ-HN35), and Obturator Functioning Scale (OFS). Data analysis was performed by one-way analysis of variance (ANOVA) on ranks, Spearman rank-order correlation, and hierarchical multivariable rank regression at α = .05 level of significance. RESULTS: Participants' gender (P < .001), adjuvant treatment (P = .016), surgical approach (P = .017), size of the maxillary defect (P = .028), participants' prosthetic history (P = .047), and dental status of the mandible (P = .038) were significantly related to the self-reported effectiveness of the complete denture obturator prosthesis. Perceived functioning of the prosthesis (P = .001), participants' gender (P = .002), the American Society of Anesthesiologists (ASA) physical status (P = .027), and surgical approach (P = .039) were significant predictors of QOL. CONCLUSION: Restoration of the edentulous maxillectomy defect is challenging. An effective definitive complete denture obturator appeared to be the strongest predictor for advanced quality of life in older maxillectomy patients. The physical status of the older participants significantly affected the overall QOL, but did not influence the self-reported functioning of the complete denture obturator prosthesis.

Quality of life in patients with soft palate resection: The relationship between reported functional prosthetic outcomes and the patient's psychological adjustment.

STATEMENT OF PROBLEM: Tumors of the soft palate and the adjacent tissues often create considerable soft palate defects that are challenging for the maxillofacial prosthodontist. Soft palate obturator prostheses can usually address functional and esthetic concerns; however, the effectiveness of the prosthetic rehabilitation in improving the patient's well-being and overall quality of life (QOL) has not been extensively researched. PURPOSE: The purpose of the present research was to evaluate the function of the prosthesis, to review the interrelation between sociodemographic, medical, and treatment (SMT) characteristics, QOL, and prosthesis functioning, and to analyze the role of the prosthesis in how the patient represents the illness and the psychological coping response. MATERIAL AND METHODS: Thirty-three patients who underwent resection of the soft palate and had been using a technically successful soft palate obturator prosthesis for at least 1 year were interviewed by means of 5 questionnaires: European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Core Questionnaire (QLQ-C30), Head and Neck Cancer Module (QLQ-HN35), Obturator Functioning Scale (OFS), Illness Perceptions Questionnaire (IPQ-R), and Mental Adjustment to Cancer Scale (MAC). Data analysis was performed at α=.01. RESULTS: The QOL (r=-0.53, P=.001), personal control (r=-0.53, P=.001), negative adjustment to cancer (r=0.47, P=.005), treatment control (r=-0.55, P=.001), consequences (r=0.62, P<.001), and emotional representations (r=0.30, P=.009) were significantly related to prosthesis functioning. Better QOL was significantly related to prosthesis functioning (P=.006), age (P=.001), sex (P=.011), and type of soft palate defect (P=.009). The most important predictors of favorable soft palate obturator functioning were age (P<.001) and type of soft palate defect (P=.01). CONCLUSIONS: A patient-perceived effective soft palate obturator prosthesis was a significant predictor for advanced QOL, better adjustment to illness and illness-related disabilities, as well as the overall coping response to cancer.

The effect of cooling procedures on monomer elution from heat-cured polymethyl methacrylate denture base materials

Abstract Objective To evaluate the amount of methyl methacrylate (MMA) released in water from heat-cured polymethyl methacrylate (PMMA) denture base materials subjected to different cooling procedures. Methodology Disk-shaped specimens (Ø:17 mm, h:2 mm) were fabricated from Paladon 65 (PA), ProBase Hot (PB), Stellon QC-20 (QC) and Vertex Rapid Simplified (VE) denture materials using five different cooling procedures (n=3/procedure): A) Bench-cooling for 10 min and then under running water for 15 min; B) Cooling in water-bath until room temperature; C) Cooling under running water for 15 min; D) Bench-cooling, and E) Bench-cooling for 30 min and under running water for 15 min. A, B, D, E procedures were proposed by the manufacturers, while the C was selected as the fastest one. Control specimens (n=3/material) were fabricated using a long polymerization cycle and bench-cooling. After deflasking, the specimens were ground, polished and stored in individual containers with 10 ml of distilled water for seven days (37oC). The amount of water-eluted MMA was measured per container using isocratic ultra-fast liquid chromatography (UFLC). Data were analyzed using Student's and Welch's t-test (α=0.05). Results MMA values below the lower quantification limit (LoQ=5.9 ppm) were registered in B, C, E (PA); E (PB) and B, D, E (QC) procedures, whereas values below the detection limit (LoD=1.96 ppm) were registered in A, D (PA); A, B, C, D (PB); C, D, E (VE) and in all specimens of the control group. A, B (VE) and A, C (QC) procedures yielded values ranging from 6.4 to 13.2 ppm with insignificant differences in material and procedure factors (p>0.05). Conclusions The cooling procedures may affect the monomer elution from denture base materials. The Ε procedure may be considered a universal cooling procedure compared to the ones proposed by the manufacturers, with the lowest residual monomer elution in water.

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

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

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.

Effects of sociodemographic, treatment variables, and medical characteristics on quality of life of patients with maxillectomy restored with obturator prostheses.

STATEMENT OF PROBLEM: Restoration of maxillary defects resulting from tumor ablative surgery presents a difficult challenge, with both functional and esthetic issues. Whether rehabilitation with an obturator prosthesis could significantly contribute to improved quality of life in patients with maxillary resection has been scarcely studied, with relatively small study samples. PURPOSE: The purpose of this survey study was to assess the overall functioning of the obturator prosthesis and the effect of specific sociodemographic, medical, and treatment variables on obturator functioning and quality of life in patients with maxillectomy. MATERIAL AND METHODS: Global quality of life (QOL) and satisfaction with the obturator prosthesis of 57 patients who underwent maxillectomy and prosthetic rehabilitation at the National and Kapodistrian University of Athens were assessed using 3 questionnaires: European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire C30 (QLQ-C30), the EORTC QLQ-HN35, and the obturator functioning scale. The data were analyzed using the Kruskal-Wallis 1-way ANOVA on ranks, hierarchical multiple regression analysis, and the Spearman rank order correlation (α=.05). RESULTS: Satisfactory functioning of the obturator prosthesis was the most significant predictor of improved QOL (P<.05). QOL was significantly related to additional treatments (P<.05), the size of the primary tumor (P<.05), and the size of the maxillectomy defect (P<.05). The most significant predictors of good obturator functioning were additional treatments (P<.01), age at the time of surgery (P<.05), presence of mandibular teeth (P<.05), and previous maxillary removable prosthetic experience (P<.05). Obturator functioning scale appearance and insertion subscales (r=0.47, P<.01), followed by speech (r=0.42, P<.01), were significantly related to better QOL. CONCLUSIONS: A well-functioning obturator prosthesis was the most significant determinant for improved QOL in patients with maxillary resection. Age at the time of surgery, adjuvant treatments, presence of mandibular teeth, and previous maxillary removable prosthetic experience were the most significant predictors for better obturator functioning, whereas the size of the maxillectomy defect had a significant effect on QOL but did not influence the functional outcome.

The Use of a Modified Poly-Ether-Ether-Ketone (PEEK) as an Alternative Framework Material for Removable Dental Prostheses. A Clinical Report.

This clinical report presents a modified poly-ether-ether-ketone (PEEK) as an alternative material for the fabrication of distal extension removable dental prosthesis (RDP) frameworks. This material can be used for patients allergic to metals, or who dislike the metallic taste, the weight, and the unpleasant metal display of the denture framework and retentive clasps. This modified PEEK material, known as BioHPP, is a biocompatible, nonallergic, rigid material, with flexibility comparable to bone, high polishing and low absorption properties, low plaque affinity, and good wear resistance. It has been used for years in orthopedics and medical technology. BioHPP frameworks can be constructed either via CAD/CAM manufacturing or via the conventional lost wax technique. The clinical use of a BioHPP RDP framework is presented as an alternative for the treatment of a distal extension case.

Monitoring Shore A hardness of silicone facial elastomers: the effect of natural aging and silicone type after 1 year.

OBJECTIVES: The purpose of this study was to investigate the effect of natural aging after storage in the dark for 1 year and material type on Shore A hardness of 2 silicone prosthetic elastomers. MATERIALS AND METHODS: The silicone elastomers tested were low- and high-temperature vulcanizing materials, namely, Premium and Silasto 30, respectively. Ten samples, 25 × 25 × 10 mm3, from each silicone were made and stored in sealed glass containers in the dark. Shore A hardness was measured according to the American Society for Testing Materials specification D2240. Three recordings were made on each sample at baseline and then weekly for 12 months (quadruplicate per mo). Data were analyzed by general linear modeling for repeated measures and Student-Newman-Keuls test for post hoc comparisons at α = 0.05. RESULTS: General linear modeling analysis indicated a significant influence of either silicone type (F = 229.5, P = 0.0001) or natural aging (F = 105.9, P = 0.0001) or their interaction (F = 27.6, P = 0.0001) on Shore A hardness values. For Premium and Silasto 30, Shore A hardness ranged from 16.9 to 26.0 and 32.0 to 36.3, respectively. The elastomers showed a trend to increase hardness over natural aging, which was significant (Premium) or not (Silasto 30), depending on the material and time intervals. CONCLUSIONS: Premium silicone showed a significant hardness increase after 1 year of natural aging in the dark, reaching a convergent value approximately 6 months from the onset, whereas Silasto 30 hardness remained stable during this period. Both elastomers showed Shore A hardness values within clinical acceptable limits after aging.

Dynamic mechanical thermal analysis of maxillofacial prosthetic elastomers: the effect of different disinfecting aging procedures.

In this study, dynamic mechanical thermal analysis was used to evaluate the changes that occurred in maxillofacial elastomers subjected to different disinfecting regimens. A commercial polydimethyl siloxane (PDMS) and an experimental chlorinated polyethylene (CPE) were treated with different disinfection procedures for a period that simulates 1 year of clinical service: microwave exposure (D1), hypochlorite solution (D2), neutral soap (D3), and a commercial disinfecting solution (D4). A fifth group was kept in dark storage as control. Dynamic mechanical thermal analysis tests operated in a fixed frequency (1 Hz) over a range of temperatures (-130°C to 20°C for PDMS, -60°C to 120°C for CPE). Loss modulus (G″), storage modulus (G'), and loss factor (tanδ) were recorded as a function of temperature. The obtained glass transition temperature (Tg) values were subjected to statistical analysis. Dynamic mechanical thermal analysis revealed changes in Tg values for both materials, which reflect the possible changes in their chemical and physical structure, after different disinfection procedures. The PDMS and CPE samples seem to have less dense structure maybe because of chain scission reaction that probably occurred during the disinfection procedures. According to statistical analysis, Tg values presented significant changes from the control samples among the different materials and disinfecting procedures. Microwave exposure and hypochlorite solution affect CPE significantly, whereas PDMS exhibited significant changes after being treated with a commercial antimicrobial agent, concerning changes that occurred in Tg. In all cases, Tg values were decreased compared with the untreated samples, which were stiffer, presenting higher Tg and G' values.

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.

Effect of different disinfecting procedures on the hardness and color stability of two maxillofacial elastomers over time

Objective Disinfection procedures often cause deterioration in a maxillofacial prosthesis. Color and hardness alterations could lead to a replacement of the prosthesis. Material and Methods An experimental chlorinated polyethylene (CPE) and a commercial polydimethyl siloxane (PDMS) sample were treated with four different disinfection procedures for a period which simulates 1 year of clinical service. The applied disinfection procedures included microwave exposure and immersion in three solutions, sodium hypochlorite, neutral soap and a commercial disinfecting soap. Shore A hardness (∆H) and color differences (∆E) were determined before and after each procedure. All data were analyzed by Two Way Analysis of Variance (ANOVA) and Tukey's post hoc tests at a level of α=0.05. Results The samples presented significant alterations in color and hardness after the different disinfection treatments. The color differences (∆E) were at least eye detectable in all cases and clinically unacceptable in most of the cases, with values ranging from 1.51 to 4.15 and from 1.54 to 5.92 for the PDMS and CPE material, respectively. Hardness was decreased after all the disinfection procedures in the PDMS, while for the CPE, a decrement was observed after disinfection with sodium hypochlorite and neutral soap and an increment after microwave exposure and the disinfection with a commercial antimicrobial agent. The PDMS samples presented greater alterations in color and hardness after disinfection with sodium hypochlorite solution, while the microwave exposure caused negligible effects. The CPE samples were affected most after disinfection when treated with neutral soap, and more slightly when disinfected with sodium hypochlorite solution. Conclusions The disinfection procedures caused alterations in color and hardness of the examined materials. The most suitable disinfection procedure for ...

Treatment of hemi-mandibulectomy defect with implant-supported telescopic removable prosthesis. A clinical report.

Excision of head and neck tumors (benign or malignant) often leads to large segmental resections of the mandible. The following clinical report describes the oral rehabilitation of a 60-year-old Caucasian man after partial mandibulectomy due to primary oral leiomyosarcoma. Treatment consisted of a free fibula flap and an implant-supported telescopic removable prosthesis.

Antimicrobial efficacy of denture adhesives on some oral malodor-related microbes.

The objective of the study was to determine the antimicrobial efficacy of three denture adhesives toward Streptococcus oralis, mutans, Prevotella oralis and Fusobacterium nucleatum. Adhesives used were Corega Ultra(®), Fixodent Pro Original(®) and Biotene(®) Denture Grip. For Streptococcus oralis and Streptococcus mutans, four tubes of Trypticase Soy Broth 10 mL and 1 g denture of adhesive were used. In addition four tubes of Trypticase Soy Broth 10 mL without any denture adhesive was employed as control. For Prevotella oralis and Fusobacterium nucleatum, four tubes of thioglycolate 10 mL and 1 g denture adhesive were used for each one, while four tubes of thioglycolate 10 mL without adhesive served as control. All samples were incubated for 48 h at 37°C. After 48 h, the number of colonies was counted and the mean was extracted as cfu/mL. The results were evaluated with ANOVA on ranked data and Tukey's post hoc test at α = 0.05. Streptococcus oralis, mutans, Prevotella oralis and Fusobacterium nucleatum showed decreased number of colonies for each denture adhesive compared to the control. Under the conditions of this in vitro study, all the tested denture adhesives showed antimicrobial efficacy. However, in contrast to the hypothesis, there were differences among them. Corega Ultra(®) and Biotene(®) Denture Grip were more effective for all the tested oral malodor-related microbes than Fixodent Pro Original(®).

Effectiveness of mechanical brushing with different denture cleansing agents in reducing in vitro Candida albicans biofilm viability

The adhesion of Candida albicans to surfaces is the prerequisite for occurrence of denture stomatitis, a common disease diagnosed among denture wearers. A routine of denture cleansing is essential to prevent biofilm formation and the onset of this infection. The aim of this study was to investigate the effectiveness of combining brushing and cleansing agents in killing C. albicans biofilm. Disks of acrylic resin were made, sterilized, and inoculated with C. albicans (10(7) cfu/mL). After incubation (37°C/48 h), specimens were randomly assigned to 10 experimental groups (n=9): 5 subjected to brushing with distilled water or cleansing agents - dentifrice slurry, 2% chlorhexidine gluconate (CHX), 1% sodium hypochlorite (NaOCl), and Polident fresh cleanse® (combined method) - and 4 exposed to the cleansing agents without brushing (immersion). Non-cleansed specimens were used as positive controls. The viability of cells was evaluated by XTT reduction method. Results were analyzed by Mann-Whitney and Kruskal-Wallis tests (α=0.05). The combined method was significantly more effective (p<0.0001) in reducing biofilm viability than the immersion. Brushing with CHX and NaOCl resulted in 100% removal of the biofilm. Immersion in the agents reduced significantly (p<0.0001) the biofilm viability, with CHX being the most effective (p<0.0001). The use of the combined method of brushing with cleansing agents is an effective method to reduce C. albicans biofilm, being CHX and NaOCl the most effective solutions.

A adesão de Candida albicans às superfícies é o primeiro passo para o desenvolvimento da estomatite protética, uma infecção frequente diagnosticada entre os usuários de próteses. Uma adequada higienização é essencial para prevenir a formação de biofilme microbiano e o início desta infecção. O objetivo deste estudo foi avaliar a efetividade da escovação com diferentes soluções na eliminação de biofilme de C. albicans. Para isso, discos de resina acrílica foram confeccionados, esterilizados e inoculados com uma suspensão de 10(7) células/mL de C. albicans. Após incubação (37°C/48 h), os espécimes foram aleatoriamente divididos em 10 grupos experimentais (n=9): 5 submetidos à escovação com água ou agentes de limpeza (água destilada, dentifrício, digluconato de clorexidina (CHX) a 2%, hipoclorito de sódio (NaOCl) a 1% e Polident fresh cleanse®) e 4 apenas imersos nos agentes de limpeza. Espécimes não submetidos à higienização foram utilizados como controle positivo. A viabilidade celular foi verificada pelo teste de redução do XTT. Os resultados obtidos foram analisados pelos testes de Mann-Whitney e Kruskal-Wallis (α=0,05). A escovação com todos os agentes de limpeza apresentou redução significativamente superior (p<0,0001) na viabilidade do biofilme quando comparada à exposição dos espécimes às soluções. Escovação com CHX a 2% e NaOCl a 1% resultaram em 100% de inativação do biofilme. A exposição aos agentes de limpeza resultou em redução significativa (p<0,0001) na viabilidade celular, com CHX a 2% sendo o mais efetivo (p<0,0001). A utilização de agentes de limpeza em associação ao método de escovação provou ser efetivo para reduzir biofilme C. albicans, sendo as soluções de CHX e NaOCl as mais efetivas.

Effect of immersion cleansing in color stability and hardness of soft denture reliners.

Hygienic care of removable prostheses is important, and denture cleansers selected must be efficient and maintain the physicomechanical properties of soft reliners. Microwave energy has been reported to increase the sanitation effectiveness of denture cleansers. The purpose of the study was to evaluate hardness and color stability of some visible light polymerized and autopolymerized soft reliners after exposure in different denture-cleansing treatments. Six soft denture reliners (2 autopolymerized silicones, 1 autopolymerized acrylic, and 3 visible light polymerized ones) were exposed to 4 cleansing treatments (Corega Whitening, Polident 5-Minute, Corega Whitening + microwaving, Polident 5-Minute + microwaving). Hardness was measured with a Shore A durometer, and color changes were evaluated by a tristimulus colorimeter. The results were subjected to 2-way analysis of variance and Scheffé test for post hoc comparisons at a confidence level of α = 0.05. Sofreliner showed the smallest hardness change, and LightLiner the greatest. Versasoft and Sofreliner seem to have the lowest color change for every cleansing treatment examined, whereas LightLiner and Eversoft presented the greatest. Silicone-based materials demonstrated the smallest changes in both hardness and color, either when using water or with any of the other cleansing treatments.

Optical properties of pigmented polydimethylsiloxane prosthetic elastomers: effect of "outdoor" and "indoor" accelerating aging.

OBJECTIVES: Optical properties of facial prosthetic elastomers undergo significant changes mainly due to aging. The resulting changes in their appearance are the main reasons of facial prosthesis' replacement. PURPOSE: The purpose of this study was to evaluate changes in the translucency parameter (TP) and color (ΔE*) of polydimethylsiloxane (PDMS) maxillofacial elastomers after exposure to 3 different aging conditions (time passage, accelerated "outdoor" aging, and accelerated "indoor" aging). MATERIALS AND METHODS: The PDMS prosthetic elastomers tested in this study were low- (LTV) and high-temperature vulcanized (Episil and Mollomed, respectively) in various shades. Color changes (ΔE*) and translucency parameter (TP) were determined in the CIE L*a*b* system using a tristimulus colorimeter. Data were subjected to 2-way analysis of variance followed by Tukey post hoc test. In addition, TP values were analyzed by paired t tests. The significance level of α = 0.05 was set for all tests. RESULTS: Translucency parameter values for most samples were significantly changed after aging, and ΔE* values were characterized as unacceptable. Both aging procedure and material type affected the changes that occurred. Moreover, dark-shaded samples of both silicone materials revealed significant changes in TP values before and after aging. ΔE* was not significantly different among the same material samples but had significant differences between the 2 materials (Episil and Mollomed). Time passage did not significantly affect TP values contrary to the other 2 accelerated aging procedures. Between outdoor and indoor aging, no significant differences were detected. CONCLUSIONS: Accelerated outdoor and indoor aging caused significant changes in ΔE* and TP values. Significant changes were also detected between material types.

Effect of time passage on some physical properties of silicone maxillofacial elastomers.

OBJECTIVES: Changes in color and other physical properties of silicone facial prosthesis are the main reasons for its replacement. The purpose of this study was to investigate the effect of time passage on some physical properties such as tensile strength, modulus of elasticity, elongation at break, tear strength, hardness, color stability, and contrast ratio (CR) of 2 silicone facial elastomers after being sealed in glass containers and kept in the dark for 1 year. MATERIALS AND METHODS: Specimens from 2 silicone elastomers (Silasto 30 and Premium 2) were made and stored in the dark. Tensile and tear strength tests were conducted according to International Organization for Standardization specification nos. 37 and 39, respectively, in a universal testing machine. Shore A hardness was measured according to the American Society for Testing Materials specification D 2240. Color changes (ΔΕ*) were determined in the CIE L*a*b* system using a tristimulus colorimeter, and CR also was calculated. Data were analyzed by paired and unpaired t-tests at a significance level of α = 0.05. RESULTS: Elongation at break, modulus of elasticity, and hardness were significantly changed, whereas changes in CR were observed only in 1 of the 2 elastomers. Tensile and tear strengths were not significantly changed for both of them. Within the limitations of this study, color changes (ΔΕ) were unacceptable. CONCLUSIONS: Most of the physical properties studied were significantly affected because of time passage. Mechanical and physical properties of silicone maxillofacial elastomers can be changed with time passage (natural aging in the dark). The average time of replacing a facial prostheses is 6 to 18 months; thus, it is important that the findings of this study covered a period of 12 months. Time passage seems to be a critical factor contributing to the overall deterioration of a silicone maxillofacial elastomer.

Effects of storage in simulated skin secretions on mechanical behavior and color of polydimethylsiloxanes elastomers.

BACKGROUND: Among the deteriorations that occur in maxillofacial prosthesis due to exposure in various environmental factors, sebaceous oils (sebum) and perspiration are also responsible for several alterations. PURPOSE: Mechanical properties and color changes of 3 different medical-grade polydimethylsiloxanes were investigated in this study (Elastomer 42, Techsil 25, and M511), after immersion for 6 months in simulated sebum and perspiration at 37 °C. The purpose of this study was to determine the effects of storage in their physical properties. The null hypothesis investigated was that immersion time did not affect the measured properties. METHODS: Polydimethylsiloxane specimens were immersed in simulated perspiration and in sebum. Compression tests were conducted on a Zwick testing machine. Shore A hardness measurements were carried out in a CV digital Shore A durometer. Weight changes were measured, and color changes were determined in the CIELAB system, using a MiniScan XE spectrophotometer. Simple mathematical models were developed to correlate the measured properties with the immersion time. The data were analyzed by analysis of variance and Tukey multiple range test at a level of α = 0.05. RESULTS: Specimens immersed in simulated skin secretions became harder because of facilitation of the propagation of cross-linking reaction that probably occurred during aging of the polydimethylsiloxane samples, except for Elastomer 42, which seems to become more soft and ductile after immersed in sebum. Some weight increase was observed for the specimens immersed into the aqueous solutions, whereas for those immersed in sebum, weight loss was recorded, probably because of extraction of some compounds. The color change was higher for the specimens immersed in sebum than that corresponding to simulated perspiration. According to statistical analysis, all measured properties changed significantly after immersion in simulated perspiration and in sebum. Moreover, mathematical models reveal major alterations as well, which were introduced through their constants. Thus, the hypothesis investigated was rejected. CONCLUSIONS: Significant changes were observed in all the examined elastomers. The elastomers were aged for a period, which simulates 1.5 years of clinical service. Within the limitation of this study, concerning the mechanical behavior and mostly the color changes, sebum and perspiration greatly affect the examined elastomers.