İsmail Hakkı Uzun

Bond strength of resin cement to yttrium-stabilized tetragonal zirconia ceramic treated with air abrasion, silica coating, and laser irradiation.

OBJECTIVE The purpose of this study was to evaluate the shear bond strength of a resin cement to yttrium-stabilized tetragonal zirconia (Y-TZP) surfaces treated with air abrasion, silica coating, or CO(2), Er:YAG, or Nd:YAG laser irradiation, or irradiated by each laser after air abrasion. BACKGROUND DATA Optimized methods are needed to improve the adhesive bonding between resin cement and Y-TZP ceramic. METHODS Twelve specimens were irradiated with each laser at different parameters and examined by scanning electron microscopy to determine which parameters to use in this study. One hundred forty-one Y-TZP discs were assigned to nine groups: C, no treatment; AA, air abrasion; CJ, silica coating; ER, Er:YAG laser; ND, Nd:YAG laser; CO, CO(2) laser; AA+ER, air abrasion + Er:YAG laser; AA+ND, air abrasion + Nd:YAG laser; AA+CO, air abrasion + CO(2) laser. The composite cylinders were fabricated. After the surface treatments, the specimens were silanized and composite cylinders were cemented with the resin cement. The shear bond strength test was performed after specimens were stored in water for 24 h and after thermocycling for 500 cycles. RESULTS The highest bond strength was obtained in the AA group and was similar to that of the CJ group. In C, ER, CO, ND, AA+ND, and AA+CO groups, the shear bond strengths were similar to each other according to the Duncan test results. The lowest bond value was obtained in the AA+ER group. CONCLUSION Although air abrasion and silica coating were the most effective surface treatment methods, CO(2) and Er:YAG laser irradiation alone or Nd:YAG laser irradiation after air abrasion may be used as an alternative treatment method to increase the bond strength between resin cement and Y-TZP material.

Evaluation of marginal and internal adaptation of hybrid and nanoceramic systems with microcomputed tomography: An in vitro study

Statement of problem. The accuracy of recently introduced chairside computer‐aided design and computer‐aided manufacturing (CAD‐CAM) blocks is not well established, and marginal integrity and internal adaptation are not known. Purpose. The purpose of this in vitro study was to evaluate the marginal and internal adaptation of hybrid and nanoceramics using microcomputed tomography (&mgr;‐CT). Material and methods. The marginal and internal adaptation of 3 polymer‐infiltrated ceramic‐network (PICN) materials (Vita Enamic [VE]; Lava Ultimate [LU]; Vita Suprinity [VS]) were compared with lithium disilicate (IPS e.max.CAD, IPS). Ninety‐six specimens (48 dies and 48 crowns) were prepared (n=12 each group) using a chairside CAD‐CAM system. The restorations were scanned with &mgr;‐CT, with 160 measurements made for each crown, and used in 2‐dimensional (2D) analysis. The marginal adaptation of marginal discrepancy (MD), absolute marginal discrepancy (AMD), internal adaptation of shoulder area (SA), axial space (AS), and occlusal space (OS) were compared using appropriate statistical analysis methods (&agr;=.05). Cement volumes were compared using 3D analysis. Results. The IPS blocks showed higher MD (130 &mgr;m), AMD (156 &mgr;m), SA (111 &mgr;m) (P<.05), AS (52 &mgr;m), and OS (192 &mgr;m) than the other blocks (P<.01). The adaptation values of VS were significantly lower than those of the IPS block (P<.05). The adaption values of the LU and VE blocks were significantly lower than those of others (P<.01) but were statistically similar to one another (P>.05). IPS had the largest cement space at 18 mm3 (P<.01). Conclusions. The marginal and internal adaptation values were within a clinically acceptable range for all 3 hybrids and nanoceramics tested.

In vitro evaluation of long-term cytotoxic response of injection-molded polyamide and polymethyle metacrylate denture base materials on primary fibroblast cell culture

Abstract Objective. This study investigated the long-term cytotoxic response of thermoplastic polyamide and conventional polymethyle metacrylate (PMMA) denture base materials. Materials and ethods. Twenty discs were prepared for each polyamide, heat and cold cured PMMA denture base resins (totally 60) and divided into four sub-groups (n = 5). Cytotoxicity was assessed with the direct cell contact method using cell viability and neutral red (NR) uptake assay. Each sub-group was tested at initial and after being aged for 24 h, 1 week and 8 weeks with artificial saliva according to ISO 10993 standards. Results. There were no significantly difference among the materials and control groups after initial, 24 h and 1 week testing. In 24 h testing, only Deflex was more toxic according to the Control group (p < 0.05). After 8 weeks of aging with artificial saliva, all materials were significantly cytotoxic when compared to the control group. QC20 was more toxic than Deflex and SC Cold Cure (p < 0.05). There were significant differences between the 8 week aging group and the initial, 24 h and 1 week testing for all materials (p < 0.05). Conclusions. Cytotoxicity of all tested denture base materials increased significantly after the long-term aging. Therefore, long-term aging may be useful to determine a dental materials toxicity. Polyamide denture base material had a similar toxicity profile with conventional heat- and cold-cured PMMA.

3D micro-CT analysis of void formations and push-out bonding strength of resin cements used for fiber post cementation

PURPOSE To investigate the void parameters within the resin cements used for fiber post cementation by micro-CT (µCT) and regional push-out bonding strength. MATERIALS AND METHODS Twenty-one, single and round shaped roots were enlarged with a low-speed drill following by endodontic treatment. The roots were divided into three groups (n=7) and fiber posts were cemented with Maxcem Elite, Multilink N and Superbond C&B resin cements. Specimens were scanned using µCT scanner at resolution of 13.7 µm. The number, area, and volume of voids between dentin and post were evaluated. A method of analysis based on the post segmentation was used, and coronal, middle and apical thirds considered separately. After the µCT analysis, roots were embedded in epoxy resin and sectioned into 2 mm thick slices (63 sections in total). Push-out testing was performed with universal testing device at 0.5 mm/min cross-head speed. Data were analyzed with Kruskal–Wallis and Mann–Whitney U tests (α=.05). RESULTS Overall, significant differences between the resin cements and the post level were observed in the void number, area, and volume (P<.05). Super-Bond C&B showed the most void formation (44.86 ± 22.71). Multilink N showed the least void surface (3.51 ± 2.24 mm2) and volume (0.01 ± 0.01 mm3). Regional push-out bond strength of the cements was not different (P>.05). CONCLUSION µCT proved to be a powerful non-destructive 3D analysis tool for visualizing the void parameters. Multilink N had the lowest void parameters. When efficiency of all cements was evaluated, direct relationship between the post region and push-out bonding strength was not observed.

Evaluation on Shear Bond Strength of Different Glass Ionomer and Hydroxy Apatite Cements Used in Ossiculoplasty

BACKGROUND Glass ionomer cements (GIC) have been widely used in dentistry for many years. In recent years, GIC have also been used for ossiculoplasty. The bond strength of GIC used in ossiculoplasty and the way they may change over the years in the cementation area are being questioned. The bonding strength of the substance may be of importance for long-term outcomes. AIMS The aim of this study was to investigate the bond strength of different GIC on ossicles. STUDY DESIGN In vitro study. METHODS Twenty ossicles were obtained from patients who had undergone ear surgery. All specimens were randomly divided into four subgroups. All specimens were inserted into a specially designed apparatus for shear bond strength (SBS) testing. The tested materials [Aqua Meron (AM), Aqua Cem (AC), Ketac Cem (KC), and Otomimix CPB (OH)] were prepared and applied according to the manufacturers instructions. The SBS was tested using a universal testing machine at a crosshead speed of 0.5 mm/min. RESULTS The mean SBSs were found to be 13.28 MPa, 23.43 MPa, 8.51MPa, and 1.78 MPa for AM, AC, KC, and OH, respectively. AC had the highest SBS, which was statistically significantly different from that of KC and OH (p<0.05). Both AM and KC had higher SBS than OH (p<0.05). CONCLUSION The results obtained in this study by investigating the bone-bonding strength of cements widely used in ossiculoplasty demonstrate that some of these substances have a greater ability to bond to ossicles compared to others. Further clinical investigations are needed to test different parameters.

The effect of repair protocols on shear bond strength to zirconia and veneering porcelain

Abstract The aim of this study was to evaluate the shear bond strength (SBS) of a new repairing material including zirconia primer to zirconia and veneering porcelain after various surface treatments. A total of 60 specimens (30 zirconia-Zr and 30 feldspathic porcelain-Feld) were prepared and divided into 6 groups (n = 10). Two surface preparations (air abrasion-AA and Erbium Yag (Er-YAG) Laser-Las) were applied to the specimens. Zr and Feld specimens treated with a grinding bur according to manufacturer advice, were used as control (C). Repair material (Cimara Zircon, VOCO, Germany) was applied to the specimens 2 mm in height. The SBS was measured in a universal testing machine at 1 mm/min crosshead speed. The SBS data (MPa) were analyzed using two-way ANOVA and Tukey HSD multiple comparison tests (α = 0.05). Significant effects of the material type (p = 0.005) and the surface treatment strategy (p = 0.000) were found. Interaction terms were also significant (p = 0.000). While the Zr-C (68,4 MPa) showed the highest SBS (p < 0.05), Zr-Las (16,4 MPa) had the lowest SBS (p < 0.05). The highest SBS value was obtained when both zirconia and veneering porcelain were treated with a grinding bur without any additional surface treatment.

Effect of impression valve system on adhesion force of impression materials to edentulous maxillary jaw: a preliminary clinical study

Objective: The purpose of this preliminary clinical study was to evaluate the effect of novel impression valve system (IVS) on adhesion force of different impression materials to edentulous maxilla. Background data: Impression materials and techniques have an important role in complete denture success. During the functional impression with an individual impression tray (IIT), high adhesive forces exist between edentulous ridge and impression material. Removing the IIT from the mouth with minimal force provides the most accurate and non-deformed impression. Materials and methods: This study included twenty maxillary edentulous patients (n = 20). Patients who had palatal torus, anatomic undercut, gagging reflex, and flabby ridges were excluded from the study. The age range of the participants was 55–70. All patients gave written informed consent. Two impression materials – zinc oxide eugenol (ZOE) and alginate – were used as experimental material. The digital dynamometer was used to determine the adhesion force of impression materials with and without IVS to edentulous maxilla. The mean values of the adhesion forces were analyzed using the Wilcoxon signed-ranks test (α = 0.05). Results: The effect of IVS on adhesion force was found to be statistically significant (p < 0.05). There were also statistical differences between the ZOE and alginate groups (p < 0.05). Conclusions: The IVS is useful to remove the functional impression from the mouth without any deformation and detaching in cases which high adhesive force occurs.

In vitro evaluation of cytotoxic effects of luting resin cements

Purpose: This in vitro study evaluated the cytotoxicity of resin cements with L929 fibroblasts. Materials and Methods: The resin cements, Super-Bond C&B, RelyX ARC, Clearfil Esthetic, specimens were prepared and extracted. The L929 cells were plated (25,000 cells/mL) and maintained. The medium was replaced with the resin extracts. Twelve specimens were used for each group. Cell viability was evaluated by 3-[4,5-dimethyl-thiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) tests. The data were analyzed by one-way analysis of variance and Tukey honest significant difference tests. Results: Clearfil Esthetic had significantly higher decreasing effect on cell survival and growth (55.64 ± 8.26%), from the other resin cements and the control (P < 001). There are no differences between the survival rates of Super-Bond C&B (72.75 ± 12.33%) and RelyX ARC (62.63 ± 10.98%) (P > 05); however, each of them was cytotoxic when they compared with the control (P < 001). Conclusion: Differential toxic effects of resin-based cement on the pulp cells should be considered during the selection.

Dental materyallerin biyouyumluluk test yöntemleri

Uzun dis hekimligi tarihi boyunca protetik tedavilerde bircok farkli materyal kullanilmistir. Gunumuzde, yeni materyallerin gelistirilmesinde fiziksel ve mekanik ozelliklerle birlikte biyolojik ozellikler de belirleyici hale gelmistir. Biyouyumluluk, bir materyalin uygulandigi bolgede uygun biyolojik cevabi olusturabilmesi olarak tanimlanir. Uygun doku cevabi, canli bir sistem uzerinde bir materyalin yan etki gostermemesi anlamina gelir. Yan etki dental materyalin toksisitesinden kaynaklanabilir. Bu nedenle dental materyalin biyouyumlu olmamasi toksik olmasinin bir nedeni olabilir. Biyouyumluluk, vucut icinde kullanilacak her materyal icin onemli bir ozelliktir. Biyolojik uyum, materyal, hasta ve fonksiyon arasindaki etkilesimin bir sonucudur ve sureklilik gostermektedir. Bir materyalin biyouyumlulugu in vitro testler, hayvan testleri ve kullanim testleri ile olculmektedir. Dental materyallerin biyolojik etkilerinin degerlendirilmesi icin in vitro hucre kulturlerinin kullanilmasi daha yaygin hale gelmektedir ve cesitli hucre kulturu metodlari dental materyallerin sitotoksisitesinin belirlenmesi icin gelistirilmistir. In vitro testler, hayvan ve kullanim testlerine gore daha basittir. Tekrarlanabilir ve kontrol edilebilir sartlarda yapilan ve karsilastirilabilir sonuclar veren bu testler, materyalin ilk kullanimi hakkinda bilgi vermektedir. Hucre ve doku kulturleri maksimum standardizasyon saglanmasinda onemli rol oynamaktadirlar. Daha guvenli dental uygulamalar icin gelecekteki calismalar materyallerin biyouyumluluguna yonelecektir. Bu makale dental materyallerin biyouyumluluk degerlendirme metodlari hakkinda genel bilgi veren bir literatur taramasidir.