Marginal Adaptation and Fracture Resistance of Lithium Disilicate Laminate Veneers on Teeth with Different Preparation Depths.

The purpose of this study was to evaluate the marginal adaptation and fracture load of ceramic laminate veneers on teeth with different preparation depths. A total of 75 extracted intact human maxillary central incisors were prepared with three different preparation depths (P) and assigned to the following five groups (n = 15): P1 (0.3-mm depth of preparation; preparation entirely in enamel); P2 (0.5-mm depth of preparation; preparation in enamel and dentin complex); P3 (1-mm depth of preparation; preparation entirely in dentin); P4 (no preparation, only surface roughening); and P5 (unrestored, intact teeth as control). A total of 60 lithium disilicate laminate veneers were fabricated. The marginal adaptation of the veneers was evaluated by light microscope and scanning electron microscope after cementation with resin cement. Finally, the veneers were loaded until fracture at a 90-degree angle to the lingual surface of the tooth. Statistical analyses were performed using analysis of variance and Tukey multiple range test. There was a significant difference between the marginal gap value of the distocervical measurement points of P1 and P2 and the distal measurement points of P3 and P4 (P = .33 and P = .017, respectively). The highest fracture resistance values were observed in the P5 group (mean: 389.55 ± 22 N) and the P2 group (mean: 322.86 ± 79.38 N), and the lowest values were observed in the P3 group (mean: 219.21 ± 60.74 N). The marginal adaptation of the laminate veneer restorations was not related to the depth of preparation. Mean fracture resistance of laminate veneers with 0.5-mm preparation depth was greater than that of the 0.3-mm and 1-mm preparation depth laminate veneers and those with no preparation.

Comparison of marginal and internal fit of press-on-metal and conventional ceramic systems for three- and four-unit implant-supported partial fixed dental prostheses: An in vitro study.

STATEMENT OF PROBLEM: Adaptation is an important factor in the long-term clinical success of implant supported ceramic restorations. Ceramic firings may affect the adaptation of the restoration. PURPOSE: The purpose of this study was to compare the marginal and internal adaptation of 3 different restorative materials and the effect of veneering/pressing on the material used for 3- and 4-unit implant supported fixed dental prostheses. MATERIAL AND METHODS: One mandibular epoxy cast was prepared for 3-unit restorations and one for 4-unit restorations. Impressions of the casts were made and 60 stone die casts (30 3-unit, 30 4-unit) produced. The casts were divided into 3 subgroups: group MCR, conventional metal ceramic restorations; group POM, press-on-metal restorations; group ZIR, computer-aided design/computer-aided manufacturing CAD/CAM) zirconia restorations. A replica technique was used to examine the marginal and internal gap values. A total of 2400 measurements were made by making 40 measurements of each restoration. The data were evaluated statistically using analysis of variance and the least significant difference post hoc test (α=.05). RESULTS: The lowest marginal gaps were found in group POM (81.58 µm) and the highest in group MCR (103.82 µm). The differences in marginal adaptation measurements were found to be statistically significant. The highest values for internal adaptation were found at the occlusal surface in all groups. CONCLUSIONS: Although veneering metal ceramic restorations increased the misfit of the restoration, the marginal discrepancy of the materials (81 to 120 µm) can be considered clinically acceptable.

Marginal-internal adaptation and fracture resistance of CAD/CAM crown restorations.

This study evaluated the marginal adaptation and fracture resistance of CAD/CAM-fabricated zirconia crowns luted using different luting agents. Twenty crown restorations were produced using IPS ZirCAD zirconium oxide blocks (IZC), and another 20 using Lava zirconium oxide blocks (L). Ten teeth were used as control. Luting agents used were an etch-and-rinse adhesive (Variolink II) and a self-etch adhesive (Multilink Automix). Internal and marginal adaptation was evaluated using silicone replica technique. Fracture resistance was evaluated using a compression test. Marginal discrepancy was 89.26 µm for L crowns and 88.84 µm for IZC crowns, and difference was statistically insignificant. However, L crowns showed significantly larger axial and occlusal gaps than IZC crowns (p<0.05). Fracture resistance of IZC-Multilink was higher than the other groups, although the difference was not significant. Results showed that CAD/CAM-fabricated crowns showed acceptable in vitro marginal discrepancies and fracture strengths.

Effects of implant angulation, impression material, and variation in arch curvature width on implant transfer model accuracy.

PURPOSE: The effects of implant angulation, impression material, and variation in width of the arch curvature on transfer models were evaluated. MATERIALS AND METHODS: Three edentulous maxillary epoxy resin models were fabricated, and six internal-connection implant analogs were placed in different locations and different angulations in each model. In the first model, implants were positioned in the canine, first premolar, and first molar regions, and all analogs were positioned parallel to each other and perpendicular to the horizontal crestal plane (parallel model). In the second model, analogs were positioned in same regions (canine, first premolar, and first molar), but three of them were positioned with 10-degree buccal angulations (versus the horizontal crestal plane) (angular model). In the third model, analogs were inserted in the lateral incisor, canine, and second molar regions and parallel to each other (wide-arch model). Eighteen impressions of each model were made with each of the three materials--condensation silicone, polyvinyl siloxane, and polyether--and impressions were poured and kept at room temperature for 24 hours. They were then observed under a toolmaker's microscope, with epoxy resin models of each group used as references. Distance deformations between implants in each model in the x- and y-axes were recorded separately. Implant angulation deformations were recorded in the x-z plane. Statistical evaluations were performed with analysis of variance and the least significant difference post hoc test. RESULTS: Angular model measurements showed the greatest deformation values (P < .05). All impression materials showed deformation, and the polyether impression models showed statistically significantly less deformation in angular measurements (P < .05). CONCLUSIONS: The models with implants placed parallel to each other exhibited greater accuracy than a model with implants placed at angles to each other.

Experimental custom-made zirconia abutments for narrow implants in esthetically demanding regions: a 5-year follow-up.

PURPOSE: This prospective clinical study evaluated an experimental custom-made zirconia abutment with respect to peri-implant hard and soft tissue reaction in narrow implants. MATERIALS AND METHODS: Patients were treated with prefabricated titanium implants and custom-made zirconia abutments. All-ceramic crowns were fabricated and cemented with resin cement. Clinical parameters such as Plaque Index, Sulcus Bleeding Index, peri-implant probing depth, and radiographic marginal bone loss levels were recorded, along with any biologic and mechanical complications, at baseline and up to 5 years. RESULTS: Twelve patients with missing maxillary lateral incisors treated with a total of 23 implants were evaluated. Thirteen Straumann Narrow Neck Solid Screw implants with a diameter of 3.3 mm and 10 Astra MicroThread implants with a diameter of 3.5 mm were used. Six patients with 11 implants were treated with custom-made zirconia abutments and prefabricated metal abutments were used in the control group. Implant and abutment success at 5 years was 100%. No abutment fractures occurred. Abutment screw loosening was reported for one restoration at the 1-year recall. Mean marginal bone loss measured 0.21 mm after 5 years of functional loading. CONCLUSION: Custom-made zirconia abutments offered sufficient stability to support all-ceramic restorations over narrow implants in anterior regions over a 5-year period. The soft and hard tissue reactions to zirconia were favorable.

Effects of thermocycling on the retention of various cements of one-unit and three-unit fixed implant-supported restorations.

PURPOSE: To investigate the physical retention of different cements on one-unit and three-unit implant-supported restorations before and after thermocycling. MATERIALS AND METHODS: Twenty acrylic resin maxilla models with a single missing tooth and three missing teeth were fabricated and implants were placed. Cast partial denture copings were cemented to Straumann solid abutments with seven different cements. Specimens were placed in a humidifier at 37°C for 24 hours; half of them were then subjected to thermocycling. The tensile force was measured using a universal testing machine with a crosshead speed of 0.5 mm/min. The retention force required to remove the specimens was recorded and the data were submitted to statistical analyses. RESULTS: The retentive strength of the cements was highest for Multilink Implant, followed in descending order by Kavitan Cem, Adhesor Carbofine, Premier Implant, Adhesor, RelyX Temp, and Cavex before and after thermocycling for both one- and three-unit restorations. The bond strength was statistically significantly higher for three-unit than for one-unit restorations before and after thermocycling, and there were statistically significant differences between cements for all groups before and after thermocycling. Both groups showed a statistically significant decrease in bond strength after thermocycling, and the largest differences were seen for Cavex and RelyX Temp for one-unit restorations and Cavex, RelyX Temp, and Kavitan Cem for three-unit restorations. CONCLUSIONS: The bond strength value was higher for three-unit than for one-unit restorations, and thermocycling reduced the bond strength of cements, especially Cavex, RelyX Temp, and Kavitan Cem.

Internal and marginal adaptation of pressable and computer-aided design/computer-assisted manufacture onlay restorations.

The aim of this research was to evaluate internal and marginal adaptation of lithium disilicate partial crowns fabricated using IPS e.max Press and IPS e.max CAD systems. Forty maxillary first molars were divided into two groups. The margins were located above the cementoenamel junction mesially and below it distally. The adaptation of the restoration was evaluated by means of the silicone replica technique. The lowest marginal discrepancy was measured between the preparation margin on the enamel and the IPS e.max Press specimens; the highest discrepancy was observed on the occlusal surface of the IPS e.max CAD specimens. Both systems tested demonstrated acceptable marginal discrepancies in vitro.

Stability and marginal bone loss with three types of early loaded implants during the first year after loading.

PURPOSE: To determine the change in stability of three different implant systems using resonance frequency analysis (RFA) and to correlate RFA measurements with factors related to implant design, length, and diameter, patient gender, and dental arch. Clinical and radiologic evaluations were performed up to 1 year after loading. MATERIALS AND METHODS: Three different types of implants from three different manufacturers were inserted in the posterior maxilla and mandible. RFA measurements were performed at implant placement and weekly up to 8 weeks postoperatively and were compared with respect to implant type, length, and diameter and dental arch. The implants were loaded after 8 weeks. All implants were examined radiographically at baseline and at 6 and 12 months. Plaque Index, Sulcus Bleeding Index, peri-implant probing depths, and marginal bone loss were recorded. Repeated-measurements analysis of variance, two-tailed mixed-model analysis of variance, the Least Significant Differences and Mann-Whitney U tests were used for statistical analyses. RESULTS: All the groups showed high stability values at all time points (above 71). There were statistically significant differences between groups at all time points except 1 and 2 weeks. Mandibular implants showed statistically higher stability values than maxillary implants. Wide implants showed statistically higher stability values than narrow implants. Mean marginal bone loss was 0.22 ± 0.47 mm after 1 year. CONCLUSIONS: All three implant systems showed clinically acceptable stability values prior to early loading. The success rates and bone loss were similar to the values reported in the literature.

The effect of different attachment systems with implant-retained overdentures on maximum bite force and EMG.

OBJECTIVE: To compare the effect of different attachment systems with implant-retained overdentures on maximum bite force and muscle activity using electromyography (EMG). BACKGROUND: Denture retention and stability is of considerable interest in prosthetic dentistry. MATERIALS AND METHODS: Thirty-five patients were examined: 15 edentulous patients treated with mandibular implant-retained overdentures (MIRO) and maxillary dentures (MCD) (two implant-ball attachment) (BC); 10 edentulous patients treated with MIRO and MCD (four implants-bar attachments) (BRC); 10 patients with edentulous mandibular treated with MIRO and maxillary fixed partial dentures (MFPD) (two implant-ball attachments) (BF). Before implant placement all patients received new dentures. After using these dentures for 3 months the maximum bite force and electrical activity of masseter muscle were measured. Two or four implants were then inserted into the intraforaminal region. After osseointegration periods, patients were treated with MIRO which duplicated their dentures and after three months the measurements were repeated. The data were collected and statistically analysed. RESULTS: Muscle activity and chewing ability increased in the second period of measurements. Also chewing time was significantly decreased at the first measurements. The highest muscle activity was observed in the group of patients treated with group BF. CONCLUSION: The EMG values of the masseter muscle significantly increased when an implant attachments was used in the overdenture.

Effect of denture adhesive on the micro-organisms in vivo.

BACKGROUND: Denture adhesives increase the retention and stability of dentures in edentulous patients, especially in cases where salivary flow is impaired or in the management of traumatised oral mucosa. OBJECTIVES: The effect of a denture adhesive on the oral flora at different time intervals. METHOD: Thirty denture-wearing patients were involved in this study. While half of the group received a denture adhesive, the other half did not. At baseline, 1 and 2 months after delivering the dentures, smear samples were obtained from the saliva, palate and the dentures. Candida albicans, Candida krusei, Candida glabrata, Candida spp., Staphylococcus aureus, Moraxella catarrhalis, α-haemolytic streptococci, ß-haemolytic streptococci, Pneumococcus aureus, S. anginosus, S. intermedius, S. constellatus, S. sanguis, S. gordonii, S. mitis, S. mutans, S. salivarius, and yeasts were investigated. The data were statistically analysed using anova and repeated measures. RESULTS: Most types of the micro-organisms were not seen and could not be analysed statistically except α-haemolytic streptococci and C. albicans. No statistically significant difference was found for α-haemolytic streptococci and C. albicans in saliva, palate and the denture at all time intervals. CONCLUSIONS: Prolonged use of the denture adhesive tested up to 2 months did not yield to increase in micro-organisms of the oral flora.

The effect of temporary hydrostatic splint on occlusion with computerized occlusal analysis system.

AIMS: The aim of this study was to evaluate the effect of temporary hydrostatic splint on occlusion with computerized occlusal analysis system. MATERIAL AND METHODS: Maximal bite force was recorded in intercuspal position by use of computerized occlusal analysis system from 11 female, 9 male, 20 subjects, (average age of 20) with normal intact dentitions. Subjects were instructed to use the hydrostatic splint for 24 h. Occlusal records were repeated three times before and after splint. All recordings were evaluated to determine the repeatability of the computerized occlusal analysis system. RESULTS AND CONCLUSION: Hydrostatic splint increased maximum biting force. Relative percentage of left and right bite forces changed in the direction of neurophysiological position of the muscles. Hydrostatic splint can be a viable option for occlusal adjustments.

Effectiveness of different cleaning agents on the adherence of Candida albicans to acrylic denture base resin.

OBJECTIVE: To evaluate the ability of three alkaline peroxide-type (Polident, Efferdent, Fittydent) and two mouth rinse cleaning agents (CloSYSII and Corsodyl) to inhibit Candida albicans on acrylic denture base resin. BACKGROUND: Appropriate routine cleaning of dentures is necessary to prevent denture stomatitis and maintenance of healthy supporting tissues. MATERIALS AND METHODS: A total of 180 acrylic resin specimens (10 × 10 × 2 mm) were prepared and divided into six groups. Candida albicans was incubated on Sabouraud dextrose agar (SDA) at 37°C for 48 h. After dilution, a final yeast suspension of approximately 10(6) C. albicans per millimetre was prepared. Ten acrylic resin specimens for each group were placed in a sterile Petri dish covered with 20 ml of fungal suspension and incubated at 37°C for 90 min. Then, the specimens were immersed in 40 ml of the test solution at 37°C for 15, 30 and 60 min. Fungal cells adhering to acrylic resin surfaces were fixed in formaldehyde and counted microscopically. RESULTS: Mouth rinses showed the highest removal activity for all the treatment times and completely eliminated the adherence of C. albicans. CONCLUSIONS: The use of mouth rinse may be a suitable method for cleaning dentures.

The association between socioeconomic status, oral hygiene practice, denture stomatitis and oral status in elderly people living different residential homes.

Oral hygiene practices and denture status of elderly people living in residential homes are different depending on the type of residential homes. In this study the elderly people living in three different residential homes were investigated for this purpose. A total of 269 subjects, 119 males (mean age 73.9±8.8) and 150 females (mean age 78.5±7.2) were involved in this study. All subjects were interviewed and clinically examined. Age, sex, educational status, financial status, general health, dental visiting, overnight denture wearing, brushing habits and frequency were recorded using a structured questionnaire. The prevalence of edentulism, the presence and type of dental prostheses, denture cleanliness and the presence of denture stomatitis were evaluated. Forty-one percent of subjects were non-educated. Fifty-one percent of subjects had low income. The majority of people (66.6%) were edentulous. Among the edentulous subjects 32% had full denture and 16% had no denture. Forty three percent of the subjects reported cleaning their dentures with water and 40% with a toothbrush only. Denture hygiene was good for 14% of the subjects. Denture stomatitis was observed in 44% of the subjects wearing dentures. There was statistically significant difference between residential homes and educational status, level of income, dental visiting, denture status, brushing methods and brushing frequency (p<0.001). A positive relationship was observed between poor denture hygiene habits and the presence of denture-related stomatitis. The most important need within the residents of the residential home was the enhancement of oral care social insurance.

Oral health status and treatment requirements of different residential homes in Istanbul: a comparative study.

The purpose of this study was to investigate dental/denture status of the elderly people living in different residential homes. In 346 elderly people from different residential homes two belonging to the state (Group 1 and Group 2) and one supported by private foundations (Group 3) were examined. Sixty percent of participants were edentulous and 22.8% of participants had no complete dentures which 9 (7.4%) of them were in Groups 1 and 2. Over 50% of the participants had no or low income and 45% of participants were illiterate. All of the participants who were illiterate and had low income were in Group 1 and Group 2. Oral hygiene was good for 15.4% and only 19.4% of participants removed their dentures overnight. Denture stomatitis was observed in 61.7% of subjects. Significant correlation was found between denture hygiene and age of participant, general health status, denture stomatitis, and overnight denture wear (p=0.001). The decayed, missing and filled teeth (DMFT) scores were 25.52±3.37. There was statistically significant differences between groups for DMFT scores (p=0.016). Dental health education is also needed focusing on the special needs of this neglected and socioeconomically deprived population to improve their quality of life.

Clinical and microbiological efficacy of three different treatment methods in the management of denture stomatitis.

OBJECTIVE: This study evaluated. the effect of mouthrinses and tissue conditioner on the clinical findings and microbial flora of 60 patients with Newton's type II denture stomatitis (N2DS) BACKGROUND: Denture stomatitis is a common problem in complete denture wearers. MATERIALS AND METHODS: Sixty patients with N2DS were included in this study and divided into three groups. Two groups of patients were instructed to rinse their mouth with the designated mouthrinses DioxiDent and Corsodyl twice daily for 1 min and to soak their dentures overnight in these solutions for 15 days. For the third group, tissue conditioner was placed in each of 20 patients' existing maxillary dentures. Patients were evaluated both clinically and microbiologically at baseline and after 15 days. Palatal swabs and smears were taken from each patient before and after treatment and these samples were examined mycologically. The difference between Candida colonisation before and after treatment and the differences between pre-treatment and post-treatment clinical findings were assessed. RESULTS: DioxiDent and Corsodyl showed an improvement in palatal inflammation and a decrease in Candida colonisation compared to Visco-gel. CONCLUSIONS: The effectiveness of topical chlorine dioxide and chlorhexidine gluconate in the management of N2DS was demonstrated.

In vivo efficacy of alkaline peroxide tablets and mouthwashes on Candida albicans in patients with denture stomatitis.

OBJECTIVE: Effective cleaning of dentures is important for the maintenance of good oral hygiene for denture stomatitis patients. The in vivo efficacy of three different brands of alkaline peroxide tablets (Polident, Efferdent, and Fittydent) and two mouthwashes (CloSYS II and Corsodyl) to eliminate Candida albicans on dentures was evaluated in this in vivo study. MATERIAL AND METHODS: Ninety denture wearers with clinical evidence of denture stomatitis were randomly divided into 5 test groups and 1 control group. Each group was further divided into three subgroups in which the dentures were subjected to 15-, 30-, and 60-min disinfection procedures. The dentures of each test group were treated with one of the cleaners, while those of the control group were treated with distilled water. Swab samples from the palatal surfaces (2 cm x 2 cm template delimited area) of the upper dentures were obtained before and after 15, 30, and 60 min periods of cleaner use and examined mycologically. RESULTS: The reduction in the number of colony-forming units (CFU) of C. albicans before, and after 15, 30, and 60 min of use of CloSYS II and Corsodyl was significantly greater than that of the control group (p<0.05). Moreover, there was no statistically significant difference (p>0.05) among Polident, Efferdent and the control group in any of the treatment periods. Dentures treated with Fittydent appeared to have a significantly greater reduction in the number of Candida spp. only after 60 min of treatment. CONCLUSIONS: The results of this study showed that the use of mouthwashes significantly reduced the number of microorganisms on dentures.

In vivo efficacy of alkaline peroxide tablets and mouthwashes on Candida albicans in patients with denture stomatitis

OBJECTIVE: Effective cleaning of dentures is important for the maintenance of good oral hygiene for denture stomatitis patients. The in vivo efficacy of three different brands of alkaline peroxide tablets (Polident, Efferdent, and Fittydent) and two mouthwashes (CloSYS II and Corsodyl) to eliminate Candida albicans on dentures was evaluated in this in vivo study. MATERIAL AND METHODS: Ninety denture wearers with clinical evidence of denture stomatitis were randomly divided into 5 test groups and 1 control group. Each group was further divided into three subgroups in which the dentures were subjected to 15-, 30-, and 60-min disinfection procedures. The dentures of each test group were treated with one of the cleaners, while those of the control group were treated with distilled water. Swab samples from the palatal surfaces (2 cm x 2 cm template delimited area) of the upper dentures were obtained before and after 15, 30, and 60 min periods of cleaner use and examined mycologically. RESULTS: The reduction in the number of colony-forming units (CFU) of C. albicans before, and after 15, 30, and 60 min of use of CloSYS II and Corsodyl was significantly greater than that of the control group (p<0.05). Moreover, there was no statistically significant difference (p>0.05) among Polident, Efferdent and the control group in any of the treatment periods. Dentures treated with Fittydent appeared to have a significantly greater reduction in the number of Candida spp. only after 60 min of treatment. CONCLUSIONS: The results of this study showed that the use of mouthwashes significantly reduced the number of microorganisms on dentures.

Factors triggering the oral mucosal lesions by complete dentures.

Oral mucosal lesions may represent acute or chronic reactions to factors related with dentures. The aim of this study was to determine the frequency of the oral lesions related to gender, age, the length of time of denture usage, the balance of denture and cleaning methods and frequency. The 106 patients who have old complete dentures came to the Dental Faculty of Marmara University, Istanbul (Turkey) to have new complete dentures were asked to participate in the investigation. The subjects (51 men and 55 women) were 37-80 years of age with a mean age of 60.28+/-10.52 years. All main factors were estimated in subgroups: cleaning methods and frequency were divided into 3 subgroups respectively as toothbrush and toothpaste/soap, denture cleansing tablets and sodium carbonate, and 3 times a day, everyday, every 3 day and once a week. The data obtained was evaluated by One-way ANOVA, Mann-Whitney U-test, Kruskal-Wallis-test, Student t-test and chi(2)-test. The level of statistical significance was set at p<0.05. The patients displayed statistically significant differences in the topics of the length of time of denture usage and the balance of denture in terms of retention. The complete denture wearers should be educated in the importance of periodic examination due to the changing of supporting tissues for detection early mucosal lesions to maintain their oral and dentures hygiene in optimum level.

Effect of 180 days of water storage on the transverse strength of acetal resin denture base material.

PURPOSE: Acetal resin has been used as an alternative denture base and clasp material since 1986. The manufacturers claim that acetal resin has superior physical properties when compared to conventional denture base acrylic resins. Limited information is available about transverse strengths of acetal resin. The purpose of this investigation was to compare transverse strengths of pink and white acetal resins to transverse strengths of conventional heat-polymerized polymethylmethacrylate (PMMA) resin in increasing durations of water storage. MATERIALS AND METHODS: A transverse strength test was performed in accordance with International Standards Organization (ISO) specification No 1567. Twenty 65 x 10 x 2.5 mm(3) specimens of each resin were prepared; five specimens of each resin group were subjected to three-point bending test after 50 hours, 30 days, 60 days, and 180 days of water storage in distilled water at 37 degrees C. Experimental groups' transverse strengths were compared by three-way ANOVA and Duncan's multiple range tests. RESULTS: Transverse strength of PMMA denture base material was found to be in accordance with the requirements of ISO specification No 1567. Transverse strengths of white and pink acetal resin could not be calculated in this study, as white and pink acetal resin specimens did not break at the maximum applied force in the three-point bending test. Flexural strength of acetal resin was found to be within the ISO specification limits. As the water storage time increased, the deflection values of PMMA showed no significant difference (p > 0.05). Both the white and pink acetal resin showed significant increase in deflection as the water storage time was increased from 50 hours to 180 days (p < 0.05). CONCLUSION: The results of this study indicated that transverse strength values of PMMA were within the ISO specification limit. Water storage time (50 hours, 30, 60, and 180 days) had no statistically significant effect on the transverse strength and deflection of PMMA. Acetal resin suffered from permanent deformation, but did not break in the three-point bending test. Acetal resin showed significant increase in deflection as the water storage time was increased from 50 hours to 180 days. All materials tested demonstrated deflection values in compliance with ISO specification No 1567.

The effect of surface roughness of silicone-based resilient liner materials on the adherence of Candida albicans and inhibition of Candida albicans with different disinfectants.

PURPOSE: The objective of the present study was to evaluate surface roughness and adherence of Candida albicans and to determine the effectiveness of denture cleansers in the disinfection of silicone-based soft lining materials. MATERIALS AND METHODS: Two types of silicone-based soft lining materials (four room temperature polymerised soft lining materials [RTPSLM]: Ufi Gel P, Ufi Gel C, Mollosil and Soft-Liner; and two high temperature polymerised soft lining materials [HTPSLM]: Moloplast B and Luci Soft) and seven denture cleansers (Efferdent, Polident, Steradent, Corega, Denclen, Klorhex and Axion) were tested in the present study. For each soft lining material, 56 samples (10 mm x 10 mm x 3 mm) were prepared. Surface roughness measurements were made using a profilometer with an optical scanner probe. All samples were ultrasonically cleaned in water for 15 s, autoclave sterilised and contaminated with C. albicans solutions for adherence assay evaluation. After the evaluation, the samples were immersed in seven different denture cleansers. The results were expressed as the ratio of cells remaining after each cleanser in comparison with the control group. RESULTS: HTPSLM showed a lower surface roughness value (2.21 +/- 0.30 lm) than RTPSLM (2.39 +/- 0.40 lm), but these differences were not statistically significant (P > 0.05). Also, HTPSLM showed lower adhesion of C. albicans (mean ranks 136.35) than RTPSLM (mean ranks 138.64), but the differences were not statistically significant (P > 0.05, one- or two-way analysis of variance). In the C. albicans removal test, all denture cleansers showed a strong effect on both silicone-based soft lining materials. HTPSLM showed lower removal activity (mean ranks 30.01) than RTPSLM (mean ranks 25.86), but these differences were not statistically significant (P > 0.05). Although there were no significant differences between disinfectants on both silicone-based soft lining materials, Axion was found to be the most effective disinfectant. Corega, Polident, Denclen, Steradent and Efferdent showed the most effective cleansing, respectively. CONCLUSIONS: RTPSLM and HTPSLM did not show significant differences in the surface roughness value; also they showed no significant differences in the adhesion rate of C. albicans. All tested silicone-based soft lining materials showed adherence of C. albicans after contamination procedures, and removal activity for C. albicans was observed in all tested silicone-based soft lining materials after disinfection procedures.