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Öğe Bond Strength Between Root Dentin and Three Glass-Fiber Post Systems(Mosby-Elsevier, 2006) Kalkan, Mustafa; Üşümez, Aslıhan; Öztürk, A. Nilgün; Belli, Sema; Eskitaşcıoğlu, GürcanStatement of problem. Glass-fiber posts were introduced for use after endodontic therapy instead of metal alloy and ceramic posts. There are several new types of glass-fiber post systems available, but little is known about how well these posts bond to the root surface. Purpose. The purpose of this in vitro study was to compare the bond strengths of 3 different types of glass-fiber post systerns-opaque, translucent, and electrical glass-in 3 different locations of prepared post spaces. Material and methods. Sixty human intact single-rooted extracted teeth were used. The root canals were prepared using a step-back technique and obturated with gutta-percha using lateral condensation. The roots were divided into 3 experimental groups and further divided into 2 subgroups according to testing time (n = 10). Roots were restored with 1 of the following post systems according to the manufacturer's instructions: opaque glass-fiber posts (Snowpost), translucent glass-fiber posts (FiberMaster), and electrical glass-fiber posts (Everstick). A self-etching primer (Clearfil Liner Bond) was applied to the walls of the post spaces, allowed to etch for 30 seconds, and gently air dried. A dual-polymerized bonding agent (Clearfil Liner Bond, Bond A and B) was then applied to the same walls. A dual-polymerizing resin luring agent (Panavia F) was mixed for 20 seconds and then placed in the post spaces using a lentulo spiral instrument. The roots were placed in light-protected cylinders; then the light source was placed directly on the flat cervical tooth surfaces and the cement was polymerized. Specimens were stored in light-proof boxes for 24 hours or 1 week after the polymerization procedure. Each root was cut horizontally, and six 1-mm-thick root segments (2 apical, 2 middle, and 2 cervical) were prepared. Using a push-out test, the bond strength between post and dentin was measured after 24 hours or I week using a universal testing machine. Statistical analysis was performed with 3-way ANOVA followed by independent t tests (alpha = .05) to detect differences between groups defined by the specific interacting variables. The different combinations of posts and luting material from the cervical segments were analyzed with SEM. Results. The 3-way ANOVA indicated that push-out test values varied significantly according to the post system used (opaque, electrical, and translucent) (P < .01); the root segments (cervical, middle, and apical) (P < .01), however, did not vary statistically according to the time of testing (24 hours and 1 week). Opaque and electrical glass-fiber posts showed higher bond strength values than translucent posts (P < .01). Push-out bond strength values of cervical segments were significantly higher than the middle and apical segments in translucent and electrical glass-fiber post groups (P < .01). In the opaque glass-fiber post group, there were no significant differences between cervical and middle segments. In SEM analysis, a distinct hybrid zone with long, numerous resin tags located between luting material and dentin was exhibited in all post systems. Conclusion. The opaque and electrical glass-fiber posts exhibited similar bond strengths, and translucent posts exhibited the lowest bond strength. The highest bond strength was observed in the cervical third of the post spaces for translucent and electrical glass-fiber post groups.Öğe Bond Strengths of Porcelain Laminate Veneers to Tooth Surfaces Prepared With Acid and Er,cr : Ysgg Laser Etching(Mosby-Elsevier, 2003) Üşümez, Aslıhan; Aykent, FilizStatement of problem. The erbium, chromium: yttrium, scandium, gallium, garnet (Er,Cr:YSGG) hydrokinetic laser system has been successful in the ablation of dental tissues. It has been reported that this system is also useful for preparing tooth surfaces for adhesion, but results to date have been controversial. Purpose. This in vitro study evaluated the bond strengths of porcelain laminate veneers to tooth surfaces after etching with acid and Er,Cr:YSGG laser conditioning. Material and method. Forty extracted caries- and restoration-free human maxillary central incisors were used. The teeth were sectioned 2 mm below the cementoenamel junction. The crowns were embedded in autopolymerizing acrylic resin with the labial surfaces facing up. The labial surfaces were prepared with .05 mm reduction to receive porcelain veneers. The teeth were divided into 4 groups of 10 specimens. Thirty specimens received 1 of the following Surface treatments before the bonding of IPS Empress 2 laminate veneers: (1) laser radiation from an Er,Cr:YSGG laser unit; (2) 37% orthophosphoric acid; and (3) 10% maleic acid. Ten specimens received no surface treatment and served as the control group. The veneers were bonded with dual-polymerizing resin, Variolink II. One microtensile specimen from each of the cervical and incisal thirds measuring 1.2 x 1.2 mm was prepared with a slow-speed diamond saw sectioning machine with a diamond-rim blade. These specimens were attached to opposing arms of the microtensile testing device with cyanoacrylate adhesive and fractured under tension at a crosshead speed of 1 mm/min, and the maximum load at fracture (Kg) was recorded. The data were analyzed with a 2-way analysis of variance and Tukey HSD tests (alpha=.05). Results. No statistically significant differences were found among the bond strengths of veneers bonded to tooth surfaces etched wish Er,Cr:YSGG laser (12.1 +/- 4.4 MPa), 37% orthophosphoric acid (13 +/- 6.5 MPa), and 10% maleic acid (10.6 +/- 5.6 MPa). The control group demonstrated the lowest bond strength values in all test groups. Statistically significant differences were found between the bond strengths of cervical and incisal sections (P<.001). Conclusion. In vitro microtensile bond strengths of porcelain laminate veneers bonded to tooth surfaces that were laser-etched showed results similar to orthophosphoric acid or maleic acid etched tooth surfaces.Öğe Effect of Cavity Preparation Techniques and Different Preheating Procedures on Microleakage of Class V Resin Restorations(2012) Karaarslan, Emine Şirin; Üşümez, Aslıhan; Öztürk, Bora; Cebe, Mehmet AtaObjectives: This study aimed to evaluate the extent of microleakage of a single type of composite resin (Clearfil Majesty Posterior, Kuraray, Osaka, Japan) following different preheating procedures in Class V cavities prepared with a diamond bur or Er:YAG (erbium: yttrium aluminum garnet) laser. Methods: The study randomly divided 72 permanent molar teeth divided into eight groups (n = 9): G1: Diamond bur-unheated composite resin (room temperature-24°.C); G2: Diamond bur-composite preheated to 37°.C; G3: Diamond bur-composite preheated to 54 °C; G4: Diamond bur-composite preheated to 68 °C; G5: Er:YAG laser-unheated composite resin (room temperature-24°.C); G6: Er:YAG laser-composite preheated to 37°.C; G7: Er:YAG laser-composite preheated to 54 °C; and G8: Er:YAG laser-composite preheated to 68 °C. The specimens were subjected to a thermal cycling regimen of 5000 cycles between 5 and 55 °C; then they were immersed in a solution of 0.5% basic fuchsin dye for 24 hours. The dyed specimens were sectioned in the buccolingual direction and dye penetration was scored in a blinded manner using a five-point qualitative scale. Microleakage scores were analyzed with the Kruskall-Wallis, Mann-Whitney U, and Wilcoxon tests. Results: There were no statistically significant differences between the microleakages of composite applied to cavities prepared by either the Er:YAG laser or diamond bur (P>.05). Statistical analysis revealed significant differences between the enamel and dentin in all restorations (P<.001). However, there were no significant differences among the preheated groups (P>.05). Conclusions: For all groups, microleakage values were higher at gingival margins than at occlusal margins. The use of the Er:YAG laser at different preheating procedures did not influence the marginal sealing in Class V composite resin restorations.Öğe Effect of Complete Dentures on Dynamic Measurement of Changing Head Position: A Pilot Study(Mosby, Inc, 2003) Üşümez, Aslıhan; Üşümez, Serdar; Orhan, MetinStatement of problem. Complete dentures contribute significantly to the facial esthetics of edentulous patients. However, information as to the effect of complete dentures oil the natural position of the head is limited. Purpose. The purpose of this Pilot study was to evaluate the immediate and 30-day effect of wearing complete dentures on the dynamic natural head position measured during walking. Material and methods. The sample consisted of a volunteer group of 16 patients, 8 women and 8 men, who received new complete dentures. The ages of the subjects ranged from 45 to 64 years (mean = 52 years). Dynamic measurement of head posture was carried out by a specially constructed inclinometer device. Each Subject in turn was fitted with the inclinometer system and instructed to walk in a relaxed manner for 5 minutes. The data, measured as degrees, were stored in a pocket data logger. This procedure was repeated before insertion of dentures (T1), immediately after insertion of dentures (T2), and 30 days after insertion of dentures (T3). Stored dynamic head Posture data were transferred to computer for analysis. The means of the measurements were statistically compared with Friedman and following Wilcoxon tests (alpha =.05). Results. Twelve of 16 (75%) subjects showed an average of 4.6 degrees of cranial extension immediately after insertion of dentures. Six (37.5%) subjects showed an average of 6.4 degrees of cranial flexion, and 8 (50%) Subjects showed an average of 5.2 degrees of cranial extension at T3 relative to the T1 measurement. Dynamic head Posture measurements of the other 2 Subjects remained unchanged. There were significant differences between different measurements of dynamic head posture positions (P<.025). However, only, the T1 and T2 measurements were significantly different (P<.015). Conclusion. The findings indicate that the statistically significant average extension 4.6 degrees in Subjects immediately after insertion of complete dentures was not stable after a 30-day evaluation period and did not produce any statistically significant change. The overall effect of wearing dentures was an irregular flexion or extension pattern on dynamic head posture. (J Prosthet Dent 2003;90:394-400.).Öğe Effect of Complete Dentures on Dynamic Measurement of Head Posture(Int Amer Assoc Dental Researchi a D R/a a D R, 2003) Üşümez, Serdar; Üşümez, Aslıhan; Öztürk, N.[Abstract not Available]Öğe Effect of femtosecond laser beam angle on bond strength of zirconia-resin cement(SPRINGER LONDON LTD, 2015) Akpınar, Yusuf Ziya; Kepceoğlu, Abdullah; Yavuz, Tevfik; Aslan, Muhammed A.; Demirtağ, Zülfikar; Kılıç, Hamdi S.; Üşümez, AslıhanYttrium-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramic is widely used as an all-ceramic core material because of its enhanced mechanical and aesthetic properties. The bond strength of Y-TZP restorations affects long-term success; hence, surface treatment is required on ceramic boundaries. This study evaluated the effect of different laser beam angles on Y-TZP-resin cement shear bond strength (SBS). Forty plates of Y-TZP ceramics were randomly assigned to four groups (n = 10). A femtosecond amplifier laser pulse was applied on Y-TZP surface with different incidence angles (90A degrees, 75A degrees, 60A degrees, 45A degrees). The resin cement was adhered onto the zirconia surfaces. The SBS of each sample was measured using universal testing machine at crosshead speed of 1 mm/min. The SBS was analyzed through one-way analysis of variance (ANOVA)/Tukey tests. The results showed that the degree of laser beam angle affects the SBS of resin cement to Y-TZP. The laser beam was applied to a surface with a 45A degrees angle which resulted in significantly higher SBS (18.2 A +/- 1.43 MPa) than other groups (at 90A degrees angulation (10.79 A +/- 1.8 MPa), at 75A degrees (13.48 A +/- 1.2 MPa) and at 60A degrees (15.85 A +/- 0.81 MPa); p < 0.001). This study shows that decreasing of the angle between the ceramic surface and the laser beam increased the SBS between the resin cement and the ceramic material, as well as the orifice.Öğe Effect of Femtosecond Laser Treatment on the Shear Bond Strength of a Metal Bracket to Prepared Porcelain Surface(MARY ANN LIEBERT, INC, 2015) Akpınar, Yusuf Ziya; Irgın, Celal; Yavuz, Tevfik; Aslan, Muhammed Ali; Kılıç, Hamdi Şükür; Üşümez, AslıhanObjective: The aim of this study was to investigate the effects of femtosecond laser treatment (Group FS) on the shear bond strength (SBS) of a metal bracket to prepared porcelain surface, and to compare it with other surface treatment techniques [50 mu m Al2O3 sandblasting (Group SB), 9.6% hydrofluoric acid gel (Group HF), and neodymium-doped yttrium aluminium garnet (Nd:YAG laser) (Group NY)]. Background data: Because of the increasing number of adult patients in current orthodontic practice, achieving sufficient bond strength of composite resin to porcelain restorations without bond failure during the treatment is a challenge for orthodontists. Methods: In total, 80 glazed feldspathic porcelain samples were prepared and randomly assigned to four groups of 20. Treated surfaces were treated with a silane agent. Brackets were bonded to porcelain samples. The specimens were stored in distilled water for 24 h and then thermocycled for 500 cycles between 5 degrees and 55 degrees C. The SBS of the brackets was tested with a universal testing machine at a crosshead speed of 1 mm/min, until bonding failure occurred. The data were analyzed statistically using analysis of variance (ANOVA) and Tamhane multiple comparisons tests. The results of ANOVA indicated that the SBS values varied according to the surface treatment method (p<0.001). Results: Results of the Tamhane post-hoc tests indicated that the bond strength in Group NY (5.11 +/- 1.53) was significantly lower than the other groups (p<0.05). There were no statistically significant differences among Groups SB (9.07 +/- 3.76), HF (9.09 +/- 3.51), and FS (11.58 +/- 4.16) (p=0.28). Conclusions: The results of this study showed that FS treatment produced high SBS of the processes assessed; therefore, it appears to be an effective method for bonding orthodontic metal brackets to prepared porcelain surfaces.Öğe Effect of tree types of light-curing units on 5-year colour changes of light-cured composite(SPRINGER HEIDELBERG, 2009) Tak, Onjen; Altıntaş, Subutay Han; Öztürk, Nilgün; Üşümez, AslıhanThe purpose of this study was to determine colour changes in a composite cured with tungsten-halogen, light-emitting diode (LED) or a plasma arc after 5 years. Five specimens 10 mm in diameter and 2 mm in height were prepared using Hybrid (Clearfil AP-X) composite for each test group. The corresponding specimens were cured with a tungsten-halogen curing light, a LED unit or with a plasma arc. Specimens were stored in light-proof boxes for 5 years after the curing procedure to avoid further exposure to light and stored in 37A degrees C in 100% humidity. Colorimetric values of the specimens immediately after curing and after 5 years were measured using colorimeter. The Delta E* (ab) values varied significantly depending on the curing unit used (p < 0.001). Curing time did not affect the colour changes of the specimens (p = 0.4). The results of this study suggest that composite materials undergo measurable changes due to the curing unit exposure.Öğe Etching of Enamel for Direct Bonding With an Er,cr : Ysgg Hydrokinetic Laser System(Int Amer Assoc Dental Researchi a D R/a a D R, 2002) Üşümez, Serdar; Orhan, Metin; Üşümez, Aslıhan[Abstract not Available]Öğe Evaluation of curing distance of high intensity led curing units on microleakage of ceramic restorations(Selçuk Üniversitesi, 2016) Kara, Özlem; Atay, Ayşe; Güven, Mehmet Esad; Ismatullaev, Artur; Üşümez, AslıhanBackground: To assess the microleakage in slot shaped cavities restored with IPS e.max Press inlays luted with a resin cement that cured with two types of high intensity LEDs units at 0 or 9 mm distances. Methods: Forty-eight extracted human premolars were used in this study. The proximal surfaces of the teeth were prepared for the slot shaped cavities using an inlay preparation set (Komet, Germany). IPS e.max Press (Ivoclar Vivadent AG, Liechtenstein) ceramic restorations were fabricated. Two different LED units; high power intensity LED (HPIL; Demi Ultra, Kerr) and high intensity LED (HIL; Valo Cordless) were used to polymerize the dual cure resin cement (NX3 Nexus, Kerr). The curing tip distances to the restoration of 0 or 9 mm were used and controlled by using the plastic rings. The teeth were randomly divided into four groups. Group 1: No distance between the HPIL tip and the restoration, Group 2: No distance between the HIL tip and the restoration, Group 3: The distance between the HPIL tip and the restoration was 9 mm, Group 4: The distance between the HIL tip and the restoration was 9 mm. After curing, the specimens were thermocycled for 5000 cycles between 5 and 55 ?C using a dwell time of 30 s. The specimens were sealed with nail varnish, coloured by 0.5 % basic-fuchsine for 24 hours, sectioned and examined under a stereomicroscope, and scored for microleakage gingival margins. Statistical analyses were performed using Kruskal-Wallis and Mann-Whitney U-tests. Results: There were no significantly statistically differences among the groups 1, 2 and 3 (p >.05), however, the microleakage in the group 4 was greater than the other groups (p <.05). Conclusions: Increase in the distance between the HIL light source and the restoration surface resulted in an increase in microleakage values.Öğe Evaluation of mineral content of dentin prepared by erbium, chromium : yttrium scandium gallium garnet laser(SPRINGER LONDON LTD, 2008) Seçilmiş, Aslı; Altıntaş, Subutay Han; Üşümez, Aslıhan; Berk, GizemLaser etching has an effect on the mineral content of dentin. The aim of this study was to evaluate the mineral content of dentin prepared at three different power settings with an erbium, chromium:yttrium scandium gallium garnet (Er,Cr:YSGG) laser. The enamel of five, lower, wisdom, molar teeth was removed to expose the dentin surface. Four dentin slabs were obtained, then each tooth was randomly divided into four portions (groups 1 W, 2 W, 3 W and control) so that we could evaluate the effect of laser treatment. The Er,Cr:YSGG laser used for the study had a pulse duration of 140 mu s, a pulse repetition rate of 20 Hz and a power output range of 0 W to 6 W. Laser energy was delivered through a fiberoptic system to a sapphire tip terminal 6 mm long and 600 mu m in diameter, using a non-contact mode. The levels of five elements: magnesium (Mg), phosphorus (P), calcium (Ca), potassium (K), and sodium (Na), in each slab were measured by inductively coupled plasma-atomic emission spectrometry (ICP-AES). There were significant differences between the groups (1 W, 2 W, 3 W and control) for Ca, Mg, Na, P and Ca/P ratio (P<0.05); however, there were no significant differences for K (P=0.43). Laser treatment at 1 W significantly affected the mean percentage weight of all element groups except K. Scanning electron microscopy (SEM) photographs indicated that the surface irregularities increased with increasing power setting.Öğe Farklı Polisaj Yöntemleri Uygulanan Seramiklerde Yüzey Pürüzlülüğünün İncelenmesi(2001) Aykent, Filiz; İnan, Özgür; Üşümez, Aslıhan; Sevimay, MüjdeSeramik restorasyonlarda daimi simantasyondan sonra da okluzal uyumlama yapılması ve porselenin intraoral olarak polisajı gerekli olabilir. Bu nedenle porselenin intraoral olarak nasıl en ideal polisajının yapılabileceğini bilmek önemlidir. Ceramco, Vitadur-N, Ivoclar, In-Ceram ve Cerec (Pro-CAD) porselenlerinin kullanıldığı bu çalışmada; her porselen grubu için 1 x1 cm genişliğinde ve 1 mm kalınlığında 40'ar adet porselen örnek hazırlandı. Standart olarak tesviyeleri tamamlanan tüm örnekler 50\mu'luk AI2O3 kullanılarak kumlandı ve "ultrasonic cleaner"da temizlendi. Her porselen grubundaki örnekler 10'arlı 4 gruba ayrıldılar. 1. gruptaki örnekler EDENTA porselen polisaj kiti kullanılarak dakikada 15.000 devirli tur motorunda 60sn polisaj işlemine tabi tutuldu. 2. gruptaki porselenler ise her markanın talimatına uygun olarak glaze işlemine tabi tutuldu. 3. gruptaki örnekler ise 1dak. süre ile 2W gücündeki Nd:YAG lazer ışınlarına maruz bırakıldı. Son grup örnekler ise hiçbir işleme tabi tutulmadan kontrol grubu olarak bırakıldılar. Örneklerin Mitutuyo Surftest cihazı kullanılarak yüzey pürüzlülükleri ölçüldü. Sonuçlar ANOVA ve Tukey istatistik analizleri kullanılarak değerlendirildi. Tüm porselen tiplerinde glaze yapılan gruplar ile lastikle polisajı yapılan gruplar arasında fark bulunamadı (p0.05). Ancak lazer işlemine tabi tutulan gruplar, hem glaze hem de lastikle polisajı yapılan gruplardan daha pürüzlü bulundu (p0.05). Kontrol grubu örnekleri de diğer üç gruptan önemli ölçüde pürüzlü bulundu (p0.05). Porselen tipleri arasında ise Vitadur-N ve Ceramco diğer porselen çeşitlerinden daha pürüzlü bulundu (p0.05). Bunları sırasıyla Ivoclar, In-Ceram ve Cerec porselenleri izledi. Bu porselen tipleri arasında ise pürüzlülük yönünden fark bulunamadı (p0.05).Öğe Laser Etching of Enamel for Direct Bonding With an Er,Cr : YSGG Hydrokinetic Laser System(MOSBY, INC, 2002) Üşümez, Serdar; Orhan, Metin; Üşümez, AslıhanIrradiation of enamel with laser energy changes the physical and chemical characteristics of the enamel surface, and these alterations hold promise for the conditioning of enamel for bonding procedures. This laboratory study examined the influence of laser irradiation of enamel at 2 different power settings with an erbium, chromium: yttrium, scandium, gallium, garnet (Er,Cr:YSGG) hydrokinetic laser system (Millennium System, Biolase Technology, Inc; San Clemente, Calif) on the shear bond strength of orthodontic appliances and compared these with that of acid-etching. The prepared surfaces of 40 noncarious, intact, extracted premolars were exposed to laser energy: 20 teeth at 2-W setting (5.6 J/cm(2)) and 20 teeth at 1-W setting (2.7 J/cm(2)) of the commercial laser unit. Twenty teeth were etched with 37% orthophosphoric acid. Brackets were bonded with an orthodontic no-mix adhesive, and shear bond strength was determined with a universal testing machine. Data were analyzed with Kruskall-Wallis and Mann-Whitney U tests. Etched and restored surfaces of an acid-etched tooth and a 2-W laser-irradiated tooth were examined with scanning electron microscopy (SEM). Laser treatment under 2 W resulted in bond strengths of 7.11 +/- 4.56 megapascals (MPa), which was not significantly different from that of acid etching (8.23 +/- 2.30 MPa). Laser irradiation at 1 W resulted in bond strengths of 5.64 +/- 3.19 MPa, which was significantly different from that of acid etching (P < .05). However, large SD and coefficient of variation values of both laser groups made reliability of this method as an enamel conditioner questionable. Scanning electron microscopy studies of the restored irradiated surfaces showed good surface characteristics, whereas the lased surface was still more irregular than the restored acid-etched sample. Although laser devices are effectively used in some other areas of dentistry, enamel conditioning with an Er,Cr:YSGG laser cannot be considered a successful alternative to the conventional methods of increasing bond strengths to enamel.Öğe Protetik tedavilerde lazerlerin kullanımı(Selçuk Üniversitesi, 2015) Akpınar, Yusuf Ziya; Tak, Önjen; Koç, Özlem; Üşümez, AslıhanBu çalışmanın amacı lazer teknolojilerinin protetik tedavilere nasıl entegre edilebileceğini ve diş hekimliğinde kullanılan materyaller üzerindeki etkilerini tartışmaktır. Bu derleme, protetik tedavide kullanılan lazer çeşitlerini, lazer parametrelerini ve bunların materyaller olan etkileşimlerini inceleyen bilimsel çalışmaları kapsamaktadır.Öğe Shear bond strength of four resin cements used to lute ceramic core material to human dentin(2008) Altıntaş, Subutayhan; Eldeniz, Ayçe Ünverdi; Üşümez, AslıhanPurpose: This study evaluated the effect of four resin cements on the shear bond strength of a ceramic core material to dentin. Materials and Methods: One hundred twenty molar teeth were embedded in a self-curing acrylic resin. The occlusal third of the crowns were sectioned under water cooling. All specimens were randomly divided into four groups of 30 teeth each according to the resin cement used. One hundred twenty cylindrical-shaped, 2.7-mm wide, 3-mm high ceramic core materials were heat-pressed. The core cylinders were then luted with one of the four resin systems to dentin (Super-Bond C&B, Chemiace II, Variolink II, and Panavia F). Half of the specimens (n = 15) were tested after 24 hours; the other half (n = 15) were stored in distilled water at 37°C for 1 day and then thermocycled 1000 times between 5°C and 55°C prior to testing. Shear bond strength of each specimen was measured using a universal testing machine at a crosshead speed of 1 mm/min. The bond strength values were calculated in MPa, and the results were statistically analyzed using a two-way analysis of variance (ANOVA) and Tukey HSD tests. Results: The shear bond strength varied significantly depending on the resin cement used (p < 0.05). The differences in the bond strengths after thermocycling were not remarkable as compared with the corresponding prethermal cycling groups (p > 0.05). Significant interactions were present between resin cement and thermocycling (p < 0.05). After 24 hours, the specimens luted with Variolink II (5.3 ± 2.2 MPa) showed the highest shear bond strength, whereas the specimens luted with Chemiace II (1.6 ± 0.4 MPa) showed the lowest. After thermocycling, the bond strength values of specimens luted with Chemiace II (1.1 ± 0.1 MPa) and Super-Bond C&B (1.7 ± 0.4 MPa) decreased; however, this was not statistically significant (p > 0.05). The increase in the shear bond strength values in the Panavia F (4.5 ± 0.7 MPa) and Variolink II (5.5 ± 2.1 MPa) groups after thermocycling was also not statistically significant (p > 0.05). Conclusion: Variolink II and Panavia F systems showed higher shear bond strength values than Chemiace II and Super-Bond C&B. They can be recommended for luting ceramic cores to dentin surfaces. © 2008 by The American College of Prosthodontists.Öğe Temperature rise during polymerization of three different provisional materials(SPRINGER HEIDELBERG, 2008) Altıntaş, Subutay Han; Yöndem, İsa; Tak, Onjen; Üşümez, AslıhanThe purpose of this study was to evaluate the temperature rise during polymerization of three different provisional materials by direct method on two different dentin disc thicknesses. Two autopolymerizing; bis-acrylic composite (Fill-in; Kerr), polymethyl methacrylate (Temdent; Weil Dental), and one light polymerizing composite (Revotek LC; GC) provisional restoration materials were used in this study. Sixty dentin discs were prepared from extracted molars (diameter, 5 mm; height, 1 or 2 mm). These dentin discs (1 or 2 mm) were placed on apparatus developed to measure temperature rise. The temperature rise during polymerization was measured under the dentin disc with a J-type thermocouple wire that was connected to a data logger. Statistical analysis was performed with two-way analysis of variance followed by Tukey HSD test (alpha=0.05). Temperature rise values statistically varied according to the provisional restoration material used (light polymerized, auto polymerized; P < 0.001) and the dentin thickness (1 and 2 mm; P < 0.001). The polymethyl methacrylate based provisional material induced significantly higher temperature rise than other provisional restoration materials at 2-mm dentin thickness (P < 0.01). At 1-mm dentin thickness, polymethyl methacrylate and composite induced significantly higher temperature increase than bis-acrylic composite provisional material (P < 0.05). The risk for heat-induced pulpal damage should be taken into consideration during polymerization of provisional materials in deep cavities in which dentin thickness is less than 1 mm.Öğe Temperature rise during resin composite Polymerization under different ceramic restorations(2011) Yöndem, İsa; Altıntaş, Subutay Han; Üşümez, AslıhanObjectives: The purpose of this study was to measure temperature increase induced by various light polymerizing units during resin composite polymerization beneath one of three types of ceramic restorations. Methods: The resin composite (Variolink II) was polymerized between one of three different ceramic specimens (zirconium oxide, lithium disilicate, feldspathic) (diameter 5 mm, height 2 mm) and a dentin disc (diameter 5 mm, height 1 mm) with a conventional halogen light, a high intensity halogen light, or an LED unit. The temperature rise was measured under the dentin disc with a J-type thermocouple wire connected to a data logger. Ten measurements were carried out for each group. The difference between the initial and highest temperature readings was taken and the 10 calculated temperature changes were averaged to determine the mean value in temperature rise. Two way analysis of variance (ANOVA) was used to analyze the data (polymerizing unit, ceramic brand) for significant differences. The Tukey HSD test was used to perform multiple comparisons (?=.05). Results: Temperature rise did not vary significantly depending on the light polymerizing unit used (P=.16), however, the type of ceramic system showed a significant effect on temperature increases (P<.01). There were no statistically significant differences between lithium disilicate and feldspathic ceramic systems (P >.05); in comparison, the resin composite polymerized under the zirconium oxide ceramic system induced a significantly lower temperature increase than the other ceramic systems tested (P<.05) Conclusions: The resin composite polymerized beneath zirconium oxide ceramic system induced significantly smaller temperature changes. The maximal temperature increase detected in all groups in this study was not viewed as critical for pulpal health.
