PURPOSE: This in vitro study evaluated shear bond strengths of surface treatment porcelains with four porcelain repair systems simulating intraoral bonding of composite resin to feldspathic porcelain or pressable porcelain. MATERIAL AND METHODS: Eighty Porcelain disks were prepared. Group A: forty disk specimens were fabricated with Feldspathic Porcelain(Omega(R)900, Vident, Menlo Park, CA, USA). Group B: forty disk specimens were fabricated with Pressable Porcelain(IPS Empress 2 ingot, Ivoclar-Vivadent, Schaan, Liechtenstein, Germany). Each groups was divided into 4 subgroups and composite resin cylinders were bonded to specimen with one of the following four systems: Clearfil Porcelain Bond(L. Morita, Tustin, CA, USA), Ulradent Porcelain Etch.(Ultradent, Salt Lake City, UT, USA), Porcelain Liner-M(Sun Medical Co., Kyoto, Japan), Cimara Kit(Voco, Germany). After surface conditioning with one of the four porcelain repair systems, substrate surfaces of the specimen were examined microscopically(SEM). Shear bond strengths of specimens for each subgroup were determined with a universal testing machine (5mm/min crosshead speed) after storing them in distilled water at 37+/-1 degrees C for 24 hours. Stress at failure was measured in MPa, and mode of failure was recorded. Differences among four repair systems were analyzed with two way ANOVA and Duncan test at the 95% significance level. RESULTS: In the scanning electron photomicrograph of the treated porcelain surface, hydrofluoric acid etched group appeared the highest roughness. The shear bond strength of the phosphoric acid etched group was not significantly(p>0.05) different between feldspathic porcelain and pressable porcelain. But in no treatment and roughened with a bur group, the shear bond strength of the feldspathic porcelain was significantly higher than that of the pressable porcelain. In hydrofluoric acid etched group, the shear bond strength of the pressable porcelain was significantly higher(p<0.05). CONCLUSION: 1. Treatment groups showed significantly greater shear bond strengths than no treatment group(p<0.05). 2. Group with more roughened porcelain surface did not always show higher shear bond strengths. 3. In phosphoric acid etched group, there was no significant difference in shear bond strength between feldspathic porcelain and pressable porcelain(p>0.05). However in the other groups, there were significant differences in shear bond strengths between feldspathic porcelain and pressable porcelain(p<0.05).
Dental Porcelain* ; Hydrofluoric Acid ; Lakes ; Liechtenstein ; Water

STATEMENT OF PROBLEM: Unreasonable distal cantilevered implant-supported prosthesis can mask functional problems of reconstruction temporarily, but it can cause serious strain and stress around its supported implant and surrounding alveolar bone. PURPOSE: The purpose of this study was to evaluate strain of implants supporting distal cantilevered fixed prosthesis with two different cantilevered length under distal cantilevered static load. MATERIAL AND METHODS: A partially edentulous mandibular test model was fabricated with auto-polymerizing resin (POLYUROCK; Metalor technologies, Stuttgart, Swiss) and artificial denture teeth (Endura; Shofu inc., Kyoto, Japan). Two implants-supported 5-unit screwretained cantilevered fixed prosthesis was made using standard methods with Type III gold alloy (Harmony C & B55; Ivoclar-vivadent, Liechtenstein, Germany) for superstructure and reinforced hard resin (Tescera; Ivoclar-vivadent, Liechtenstein, Germany) for occlusal material. Two strain gauges (KFG-1-120-C1-11L1M2R; KYOWA electronic instruments, Tokyo, Japan) were then attached to the mesial and the distal surface of each standard abutment with adhesive (M-bond 200; Tokuyama, Tokyo, Japan). Total four strain gauges were attached to test model and connected to dynamic signal conditioning strain amplifier (CTA1000; Curiotech inc., Paju, Korea). The stepped 20-100 N in 25 N increments, cantilevered static load 8mm apart (Group I) or 16mm apart (Group II), were applied using digital push-pull gauge (Push-Pull Scale & Digital Force Gauge, Axis inc., Seoul, Korea). Each step was performed ten times and every strain signal was monitored and recorded. RESULTS: In case of Group I, the strain values were surveyed by 80.7 ~ 353.8 micrometer/m in Ch1, 7.5 ~ 47.9 micrometer/m in Ch2, 45.7 ~ 278.6 micrometer/m in Ch3 and -212.2 ~ -718.7 micrometer/m in Ch4 depending on increasing cantilevered static load. On the other hand, the strain values of Group II were surveyed by 149.9 ~ 612.8 micrometer/m in Ch1, 26.0 ~ 168.5 micrometer/m in Ch2, 114.3 ~ 632.3 micrometer/m in Ch3, and -323.2 ~ -894.7 micrometer/m in Ch4. CONCLUSION: A comparative statistical analysis using paired sample t-test about Group I Vs Group II under distal cantilevered load shows that there are statistical significant differences for all 4 channels (P<0.05).
Adhesives ; Alloys ; Axis, Cervical Vertebra ; Dentures ; Hand ; Liechtenstein ; Masks ; Prostheses and Implants* ; Seoul ; Tooth

OBJECTIVES: This study aims to compare the fluoride-release between different fluorine varnish under in vitro experimental conditions.METHODS: In this study, 5 fluoride varnish products distributed in Korea were selected. V-varnish™ (Vericom, Korea: VV), CavityShield™ (3M ESPE, USA: CS), Clinpro™ White varnish™ (3M ESPE, USA: CP), MI Varnish™ (GC, Japan: MI), and Fluor Protector (Ivoclar Vivadent, Liechtenstein: FP). For the in vitro study, 10 mg of each fluoride varnish was thinly applied to the same area of the specimen. The specimen was then immersed in 3 ml of distilled water at consistent intervals to confirm fluoride release. Nine specimens per group were used. Fluoride ion electrodes were used to measure the fluoride concentration of the solution. The Kruskal-Wallis nonparametric test was performed to compare between each experimental group, and the Wilcoxon signed-rank nonparametric test was performed to compare experimental groups over time. The significance level for a Type I error was set at 0.05. All statistical analyses were performed using SPSS 25.0 (IBM Co., Armonk, NY, USA).RESULTS: In vitro experiments showed that the amount of fluoride released from MI was higher than the other groups during the first 12 hours after application. However, the amount of fluoride released from CP and CS was higher than MI as the immersion time increased over 12 and 20 hours, respectively. The fluoride release from FP was the lowest at all measurement points.CONCLUSIONS: The results of this study showed that the remaining fluoride effect from rosin type fluoride varnishes was higher than liquid type fluoride varnishes. There were differences in the residual fluoride concentrations despite each fluoride varnish having the same fluoride content.
Dental Caries ; Electrodes ; Fluorides ; Fluorides, Topical ; Fluorine ; Immersion ; In Vitro Techniques ; Japan ; Korea ; Liechtenstein ; Paint ; Water