Browsing by Author "Schimmel, Martin"

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    Article
    Citation Count: 6
    Effect of different disinfection protocols on the surface properties of CAD-CAM denture base materials
    (Mosby-elsevier, 2023) Atalay, Sevda; Cakmak, Gulce; Fonseca, Manrique; Schimmel, Martin; Yilmaz, Burak
    Statement of problem. Which disinfection protocol provides optimal water contact angle and microhardness for computer-aided design and computer-aided manufacturing (CAD-CAM) polymethyl methacrylate (PMMA) materials is unclear.Purpose. The purpose of this in vitro study was to evaluate the effect of different disinfection protocols (1% sodium hypochlorite, denture cleanser gel, and effervescent tablet) on the water contact angle and microhardness of different CAD-CAM PMMA denture base materials by comparing them with a heat-polymerized PMMA.Material and methods. Disk-shaped specimens (o10x2 mm) were fabricated from 3 different CAD -CAM PMMAs-AvaDent (AV), Merz M-PM (M-PM), and Polident (Poli) -and a heat-polymerized PMMA (Vynacron) (CV) (n=21). Three disinfection protocols (1% sodium hypochlorite [HC], denture cleanser gel [GEL], an effervescent tablet [TAB]) were applied to simulate 180 days of cleansing. The water contact angle and microhardness of specimens were measured before and after disinfection and compared by using a 2-way ANOVA (a=.05).Results. For water contact angle, material (P=.010) and disinfection protocol (P=.002) had a significant effect. The material (P<.001), disinfection protocol (P=.001), and their interaction (P<.001) significantly affected the microhardness after disinfection. When the condition after disinfection was compared with that before disinfection, the water contact angle increased significantly in all material-disinfection protocol pairs (P<.025), and microhardness increased significantly in all material-disinfection protocol pairs (P<.040), except for GEL-(P=.689) or TAB-applied (P=.307) AV, HC-applied M-PM (P=.219), and TAB-applied Poli (P=.159).Conclusions. The material and disinfection protocol affected the water contact angle of all tested PMMAs after disinfection, resulting in more hydrophobic surfaces for heat-polymerized or CAD-CAM PMMAs. The microhardness of heat-polymerized PMMA was less than that of all CAD-CAM PMMAs after disinfection, regardless of the protocol. (J Prosthet Dent 2023;130:787-95)
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    Article
    Citation Count: 23
    Effect of thermocycling on the surface properties of CAD-CAM denture base materials after different surface treatments
    (Elsevier, 2021) Atalay, Sevda; Cakmak, Guelce; Fonseca, Manrique; Schimmel, Martin; Yilmaz, Burak
    Purpose: To evaluate the effect of thermocycling on the water contact angle (WCA), surface roughness (SR), and microhardness (MH) of different CAD-CAM PMMA denture base materials after different surface treatments (conventional laboratory polishing, polishing kit, or surface sealant). Materials and methods: Disk-shaped specimens (10 & times; 2 mm) of 3 different CAD-CAM PMMAs, AvaDent (AV); Merz M-PM (M-PM); Polident (Poli), and a conventional heat-polymerized PMMA (Vynacron) (CV) (n=21) were divided into 3 different surface treatment groups (n=7): conventional laboratory polishing (CLP), polishing with acrylic resin polisher kit (PK), and a surface sealant (Palaseal) (SSC). Stereomicroscopic images were taken both before and after thermocycling. WCA, SR, and MH of all specimens were measured before and after thermocycling and compared by using a 2-way ANOVA (alpha=0.05). Results: After thermocycling, WCA significantly increased for CLP- or PK -applied (P<.001) specimens of all materials and SSC-applied M-PM (P=.002), SR significantly increased for CLP-applied M-PM (P=.027) and PKapplied Poli (P=.041), and MH significantly decreased for CLP- or PK-applied AV (P = .001, P < .001, respectively), CV (P=.033, P=.023, respectively), and M-PM (P=.003, P=.001, respectively), SSC-applied M-PM (P<.001), and CLP-applied Poli (P<.001). Stereomicroscopic images revealed rougher surfaces for PK-applied specimens. Conclusions: After thermocycling, surface treatment had a significant effect on water contact angle and surface roughness. CLP or PK application resulted in hydrophobic surfaces compared with before thermocycling. CLP or SSC application on CAD-CAM PMMAs resulted in smoother surfaces. Thermocycling lowered the microhardness of all PMMAs, and the decrease was significant in CLP- or PK-applied PMMAs, except for PK-applied Poli.