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Öğe The effect of dentin desensitizers on thermal changes in the pulp chamber during fabrication of provisional restorations(WILEY, 2004) Usumez, A; Ozturk, AN; Aykent, FThe purpose of this study was to evaluate the effect of two dentin desensitizers on the pulp chamber temperature increase during fabrication of provisional restorations by a direct method. Sixty intact extracted mandibular third molars were prepared for a metal-ceramic complete crown. Then the teeth were randomly divided into three groups of 20 each. Group 1, no dentin desensitizer was used as the control group; group 2, a resin-based dentin desensitizer was selected; and group 3, the prepared teeth surfaces were coated with polyurethane cyanoacrylate adhesive. Each of the three groups was further divided into two polymerizing systems (autopolymerizing and a photopolymerizing) of 10 each. After insertion of the resin-filled matrix, the temperature change in the pulpal chamber was recorded with thermocouple connected to a data logger. ANOVA indicated no significant differences for all combinations of desensitizing agents and curing methods (P > 0.05). When light cured composite or chemical curing acrylics were used to make temporary crowns, the presence of desensitizing agent did not reduce the temperature transmitted from the provisional material; the residual temperature rise transmitted was of such a magnitude as to cause concern regarding possible thermal injury to pulp.Öğe Effect of provisional restorations on the final bond strengths of porcelain laminate veneers(BLACKWELL PUBLISHING LTD, 2005) Aykent, F; Usumez, A; Ozturk, AN; Yucel, MTThe purpose of this in vitro study was to evaluate the effect of the different provisional restorations cementation techniques on the final bond strengths of porcelain laminate veneers (PLVs). Thirty-six extracted human central incisors were sectioned 2 mm below the cemento-enamel junction, and crown parts were embedded into self-cure acrylic resin. Standardized PLV preparations were carried out on labial surfaces of the teeth. Then the teeth were randomly divided into three groups of 12 each. In group 1, provisional restorations were cemented with eugenol-free cement. In group 2, prepared teeth surfaces were first coated with a desensitizing agent then provisional restorations were cemented with resin cement. In group 3, provisional restorations were not fabricated to serve as control. After specimens were stored in distilled water for 2 weeks, provisional restorations were removed and final IPS Empress 2 ceramic veneers were bonded with a dual-curing resin. Two microtensile samples from each tooth measuring 1.2 x 1.2 x 5 mm were prepared. These sections were subjected to microtensile testing and failure values were recorded. The data were analysed by one-way anova and Tukey HSD tests. The PLVs, placed on the tooth surface that had received a dentine desensitizer and provisional restorations luted with resin cement (group 2), showed the lowest bond strength in all test groups. But no statistically significant differences were found between the bond strength of PLVs in control group (no provisional restorations) and group 1 (provisional restorations cemented with eugenol-free cement before final cementations). Scanning electron microscopic (SEM) examination of this study also showed that the bonding to enamel surface was better in control group and group 1 than group 2.Öğe The efficiency of different light sources to polymerize resin cement beneath porcelain laminate veneers(WILEY, 2004) Usumez, A; Ozturk, AN; Usumez, S; Ozturk, BPlasma arc light units for curing resin composites have been introduced with the claim of relatively short curing times. The purpose of this study was to evaluate the efficiency of two different light sources to polymerize dual curing resin cement beneath porcelain laminate veneers. Twenty extracted healthy human maxillary centrals were used. Teeth were sectioned 2 mm below the cemento-enamel junction and crown parts were embedded into self-cure acrylic resin, labial surface facing up. Cavity preparation was carried out on labial surfaces. These teeth were divided into two groups of 10 each. The resin cement/veneer combination was exposed to two different photo polymerization units. A conventional halogen light (Hilux 350, Express Dental Products) and a plasma arc light (Power PAC, ADT) were used to polymerize resin cement. Ten specimens were polymerized conventionally (40 s) and the other specimens by plasma arc curing (PAC) (6 s). Two samples from each tooth measuring 1.2 x 1.2 x 5 mm were prepared. These sections were subjected to microshear testing and failure values were recorded. Statistically significant differences were found between the bond strength of veneers exposed to conventional light and PAC unit (P < 0.001). Samples polymerized with halogen light showed better bond strength. The results of this study suggest that the curing efficiency of PAC through ceramic was lower compared with conventional polymerization for the exposure durations tested in this study.Öğe In vitro assessment of temperature change in the pulp chamber during cavity preparation(MOSBY, INC, 2004) Ozturk, B; Usumez, A; Ozturk, AN; Ozer, FStatement of problem. Tooth preparation with a high-speed handpiece may cause thermal harm to the dental pulp. Purpose. This in vitro study evaluated the temperature changes in the pulp chamber during 4 different tooth preparation techniques and the effects of 3 different levels of water cooling. Material and methods. The tip of a thermocouple was positioned in the center of the pulp chamber of 120 extracted human premolar teeth. Four different tooth preparation techniques were compared: (1) Low air pressure plus low load (LA/LL), (2) low air pressure plus high load (LA/HL), (3) high air pressure plus low load (HA/LL), and (4) high air pressure plus high load (HA/HL) in combination with 3 different water cooling rates. Control specimens were not water cooled; low water cooling consisted of 15 mL/min, and high water cooling consisted of 40 mL/min. Twelve different groups were established (n = 10). An increase of 5.5degreesC was regarded as critical value for pulpal health. The results were analyzed with a 3-factor ANOVA and Bonferroni adjusted Mann Whitney U test (alpha = .004). Results. For all techniques without water cooling (LA/LL/0, LA/HL/0, HA/LL/0, and HA/HL/0), the average temperature rise within the pulpal chamber exceeded 5.5degreesC during cavity preparation (7.1degreesC; 8.9degreesC; 11.4degreesC, and 19.7degreesC, respectively). When low water cooling was used with high air pressure and high load technique (HA/HL/15), the average temperature rise exceeded 5.5degreesC limit (5.9degreesC). However, when high water cooling (LA/LL/40, LA/HL/40, HA/LL/40, and HA/HL/40) was utilized, the critical 5.5degreesC value was not reached with any air pressure or load (3.1degreesC, 2.8degreesC, 2.2degreesC, and -1.8degreesC, respectively). Conclusion. Within the limitations of this in vitro study, the results indicate that reducing the amount of water cooling or increasing air pressure and load during cavity preparation increased the temperature of the pulp chamber in extracted teeth.Öğe The in vitro effect of pulpal pressure and luting agent on tensile bond strength of complete cast crowns(MOSBY-ELSEVIER, 2004) Ozturk, AN; Belli, S; Eskitascioglu, GStatement of problem. The degree to which pulpal pressure may affect bond strength of complete cast crowns is unknown. Purpose. The aim of this in vitro study was to evaluate the effect of simulated pulpal pressure on the tensile bond strength of complete cast crowns luted with 2 different cements. Material and methods. Forty-eight human mandibular canine teeth were cleaned and stored in saline solution. The crowns were prepared by I investigator, and standardization of the preparation was accomplished by fixing a dental handpiece in a parallelometer. Uniform grooves, 0.5 mm in depth, were prepared with burs with depth guides. The complete crowns were prepared with a 0.5-mm shoulder margin. Teeth were randomly divided into 2 groups of 24 teeth each (Group I and Group 11). In Group 1, bonding and tensile test procedures of the teeth were carried out under simulated pulpal pressure (15 cm of saline solution). In Group 11, simulated pulpal pressure was not used. The roots were removed I mm below the cementoenamel junction to create direct communication with the pulp chamber. The remaining pulpal tissues were carefully removed, and crowns were embedded in acrylic resin. The acrylic resin was then penetrated by a stainless steel tube that connected the pulp chamber and the barrel of a disposable plastic 5-ml syringe. The pulp chambers were filled with physiological saline solution under elevated pressure to locate the area of greatest permeability on the dentinal surface. Crowns were cast (Co-Cr alloy) with a 20-mm bar to allow testing of the bond strength. Each of the 2 groups were further divided into 2 luting cement groups of 12 each (Group 1, A and 13, and Group 11, A and B). Group IA/IIA and Group IB/IIB specimens were luted with a polycarboxylate luting cement (Poly-F Plus) and an adhesive luting cement (Superbond C&B), respectively. After storage in distilled water for 24 hours, all specimens were subjected to a tensile bond test in a universal testing machine at a crosshead speed of 0.5 mm/min until failure. The maximum load at fracture (Newton) was recorded. The results were then evaluated with 2-way analysis of variance and Tukey's honestly significant difference tests (alpha = .05). Results. Simulated pulpal pressure increased the bond strength of cast complete crowns cemented with all adhesive luting agent (P = .01). No significant difference was found in the bond strength of complete cast crowns cemented with polycarboxylate cement with or without pupal pressure. Superbond C&B adhesive luting agent showed significantly higher bond strength values for Group 1 (388.9 +/- 32.7) and Group 11 (300.9 +/- 66.8), when compared with polycarboxylate cement for Group 1 (221.3 +/- 17.3) and Group 11 (186.8 +/- 38.5) (P = .001). Conclusion. Simulated pulpal pressure had a positive effect on the retention of complete cast crowns when cemented with Superbond C&B adhesive luting agent. Superbond C&B significantly increased the retention of crowns in either the presence or absence of pulpal pressure.Öğe Influence of different light sources on microleakage of class V composite resin restorations(WILEY, 2004) Ozturk, AN; Usumez, A; Ozturk, B; Usumez, SThe aim of this study was to evaluate the effect of three different curing units on microleakage of class V composite restorations. Class V cavities were prepared on the buccal surfaces of 45 extracted premolar teeth. The teeth were randomly divided into three groups of 15 each. A conventional halogen curing unit (Hilux 350), a high intensity halogen curing unit (Optilux 501) and plasma arc curing unit (Power Pac) were used to polymerize composite resin (Vitalesence). After restoration, the teeth were thermocycled for 100 cycles between 5 degrees and 55 degreesC using a dwell time of 30 s and exposed to a dye. Results showed that there was no significant difference among three different curing units (P > 0.05), however the microleakage at the dentin margins was greater than the enamel margins (P < 0.05). Clinical relevance: Plasma arc curing or fast halogen units cure composite materials at a faster rate than conventional curing units because of the high light intensity. High intensity halogen curing units and plasma arc curing units might be useful alternatives in composite polymerization. Therefore, these units are suggested for clinical use to save chair side time.Öğe Influence of different light sources on microtensile bond strength and gap formation of resin cement under porcelain inlay restorations(WILEY, 2004) Ozturk, AN; Usumez, AClinical success with ceramic inlays/onlays has been assisted by the ability to develop a reliable bond of composite resin to dental tissues. The purpose of this study was to test the efficiency of two different light sources on microtensile bond strength and the gap formation of resin cement under class II porcelain inlay restorations. Standardized mesio-occlusal cavities were prepared in 30 freshly extracted, intact human premolar teeth. Then impressions were made and ceramic inlays were fabricated. In the cementation process, the resin cement/inlay combinations were exposed to two different photopolymerization units. The polymerizations through 15 specimens were performed with a conventional halogen light source for 60 s, and the other specimens were cured by a plasma arc light for 9 s. After the cementation process, two 1.2 x 1.2 mm wide 'I' shape sections per tooth were produced with a sectioning machine and sections were subjected to microtensile testing after 24 h or 1 week. Gap formation of specimens cured by different photopolymerization units were evaluated with scanning electron microscopy (SEM). Statistically significant differences were found between the microtensile bond strength of inlays exposed to conventional light and plasma arc curing unit (P < 0.001). Plasma arc curing units make it possible to polymerize composite in much shorter times than conventional curing unit. However, the samples polymerized with conventional halogen light produced better microtensile bond strength than the plasma arc unit.Öğe Microleakage of different cementation techniques in Class V ceramic inlays(WILEY, 2004) Ozturk, AN; Ozturk, B; Aykent, FMicroleakage between the restorative materials and the cavity walls of teeth remains a problem. The purpose of this study was to evaluate the microleakage around Class V ceramic inlay restoration using three different cementation techniques. Class V preparations were made on the buccal surfaces of 45 freshly extracted premolar teeth. The teeth were randomly divided into three groups of 15. In the first group, dentine bonding agent (DBA) (Clearfil Liner Bond 2V) was applied immediately after the tooth preparation (D-DBA). In the second group, DBA was applied to the prepared cavities while luting ceramic inlays (I-DBA). In the third group, DBA was not applied at either stage (No-DBA). Impressions were made and ceramic inlays (Ceramco II) fabricated and cemented in the Class V cavities. The restorations were stored in water at room temperature for 24 h. All restorations were thermocycled and then subjected to a dye penetration test. After sectioning, leakage at cavity/restoration interface was scored. Statistical analysis was performed using Kruskal-Wallis, Mann-Whitney U and Wilcoxon's signed tests. Results showed no significant difference among three different cementation techniques (P > 0.05). Microleakage at the dentine margins was greater than that at the enamel margins (P < 0.05).Öğe Nasal prosthesis rehabilitation: A case report(QUINTESSENCE PUBLISHING CO INC, 2004) Gurbuz, A; Kalkan, M; Ozturk, AN; Eskitascioglu, GA nasal prosthesis can reestablish esthetic form and anatomic contours for midfacial defects often more effectively than can surgical reconstruction. This case report describes the clinical and laboratory procedures for fabricating a nasal prosthesis.Öğe Temperature rise during adhesive and resin composite polymerization with various light curing sources(OPERATIVE DENTISTRY INC, 2004) Ozturk, B; Ozturk, AN; Usumez, A; Usumez, S; Ozer, FThis study evaluated the temperature rise in two different adhesive (Clearfil SE Bond [CSEB] and EBS-Multi [EBSM]) and composite systems (Clearfil AP-X [CAPX,] Pertac II [PII]) by the same manufacturer when illuminated by four different light sources: Light-emitting diode (LED), Plasma arc curing (PAC), high intensity quartz tungsten halogen (HQTH) and quartz tungsten halogen (QTH). Forty dentin disks were prepared from extracted premolars. These dentin disks were placed in apparatus developed to measure temperature rise. Temperature rise during photopolymerization of adhesive resin and resin composite was then measured. The mean values of temperature increases for adhesive and resin composites did not differ significantly (p = 0.769). The highest temperature rise was observed during photopolymerization of EBSM with PAC (5.16degreesC) and HQTH (4.28degreesC), respectively. Temperature rise values produced by QTH (1.27degreesC - 2.83degreesC for adhesive resin; 1.86degreesC - 2.85degreesC for resin composite) for both adhesive and resin composites were significantly lower than those induced by PAC and HQTH (p < 0.05). However, these values were significantly higher than those produced by LED (1.16degreesC - 2.08degreesC for adhesive resin; 1.13degreesC - 2.59degreesC for resin composite). Light sources with high energy output (PAC and HQTH) caused significantly higher temperature rise than sources with low energy output (QTH and LED). However, in this study, no temperature rises beneath 1-mm dentin disk exceed the critical 5.6degreesC value for pulpal health.
