A. Nilgun Ozturk

Surface Roughness and Morphologic Changes of Zirconia Following Different Surface Treatments

OBJECTIVE The aim of this study was to evaluate the roughness and morphology of zirconia after air abrasion and erbium:yttrium-aluminum-garnet (Er:YAG) laser application of different intensities. BACKGROUND DATA Although surface roughness is important to obtain micromechanical retention, it is unclear which surface treatment is most appropriate for zirconia. METHODS Fifty sintered zirconia specimens were divided into five groups (n=10). The following treatments were applied: control, Er:YAG laser irradiation with different energy intensities (200, 300, and 400 mJ), and air abrasion with aluminum oxide (Al(2)O(3)) particles (110 μm). Morphologic changes after surface treatments were examined in microscope analyses. Then, the surface roughness (Ra in μm) of the specimens was evaluated using a surface texture measuring instrument. Roughness data were analyzed using one-way analysis of variance (ANOVA) and Tukeys honestly significant difference (HSD) test (p=0.05). RESULTS Results of microscope analyses revealed changes in surface morphology after surface treatments, including the formation of rare pits in the 400 mJ laser group and the formation of microretentive grooves in the air abrasion group. According to the results of the statistical analysis, the mean surface roughness value for the air abrasion group was significantly higher than that of the other groups (p<0.001). Except for the air abrasion group, there were no statistically significant differences within other groups (p>0.05). CONCLUSIONS According to the results of the statistical and microscopic analyses, 400 mJ Er:YAG laser energy or air abrasion can be used to obtain micromechanical retention prior to luting; however, air abrasion is the most effective surface treatment method.

Microleakage of ceramic inlays luted with different resin cements and dentin adhesives.

STATEMENT OF PROBLEM Despite recent advances in adhesive dentistry, resin cement/dentin adhesive combinations are not able to prevent microleakage in ceramic inlays. Marginal quality of tooth-colored restorations in large Class II cavities is satisfactory in enamel margins, but microleakage in dentin margins remains a concern. PURPOSE The purpose of this study was to evaluate the microleakage of all-ceramic inlays luted with 2 dual-polymerizing resin cements or 1 autopolymerizing resin cement in combination with different dentin adhesives. MATERIAL AND METHODS One hundred and twenty extracted human mandibular third molars were used in this study. Teeth were prepared to receive Class II MOD inlays with enamel gingival margins on 1 proximal surface and dentin gingival margins on the other surface. One hundred and twenty prepared teeth were divided into 3 groups of 40; 1 group for each resin cement: RelyX ARC, Variolink II, or Panavia 21. Each of the 3 groups were further divided into 4 dentin adhesive groups; Single Bond, ExciTE DSC, ED Primer, or Admira Bond. Each of the resin cements were used in combination with the 4 dentin adhesives, and IPS Empress ceramic inlays were placed with 12 different cement/adhesive combinations. After 1000 thermal cycles in a 5 degrees -55 degrees C water bath with a dwell time of 30 seconds, all specimens were subjected to cyclic axial mechanical loading. Then the restored teeth were stored in 0.5% basic fuchsin solution for 24 hours. The extent of dye penetration along the margins was measured with a stereomicroscope at x40 magnification. The data were evaluated statistically using repeated-measures ANOVA and Duncan tests (alpha=.05). RESULTS Microleakage at dentin margins was greater than that at enamel margins (P<.05) for all groups. Variolink II and RelyX ARC resin cements showed significantly lower microleakage results than Panavia 21 with all dentin adhesives in enamel margins. For dentin margins, Variolink II/Admira Bond combination showed the lowest microleakage value in dentin (P<.05). CONCLUSIONS The overall microleakage at the enamel margins was significantly less than at the dentin margins (P<.05). Panavia 21 showed higher microleakage values than Variolink II and RelyX ARC in enamel margins.

Mechanical properties of zirconia after different surface treatments and repeated firings.

PURPOSE This study investigated the influence of surface conditioning procedures and repeated firings on monoclinic content and strength of zirconia before cementation. MATERIALS AND METHODS Sintered bar-shaped zirconia specimens were subjected to no surface treatment (control), air abrasion, or grinding (n=21). Their roughness was evaluated using a profilometer, and microscope analysis was performed on one specimen of each group. Then, 2 or 10 repeated firings (n=10) were executed, the monoclinic content of specimens was analyzed by X-ray diffraction, and a three-point flexural strength test was performed. Surface roughness values were compared using one-way analysis of variance (ANOVA) and Tukey honestly significant difference (HSD) tests, the monoclinic content values were tested using Kruskal-Wallis and Mann-Whitney U tests, and the flexural strength values were tested using two-way ANOVA and Tukey HSD tests (P=.05). Spearmans correlation test was performed to define relationships among measured parameters. RESULTS Surface-treated specimens were rougher than untreated specimens and had a higher monoclinic content (P<.005), and the relationship between roughness and monoclinic content was significant (P<.000). Neither surface treatment nor firing significantly affected the flexural strength, but Weibull analysis showed that for the air-abraded samples the characteristic strength was significantly lower after the 10th firing than after the 2nd firing. CONCLUSION After firing, a negligible amount of monoclinic content remained on the zirconia surfaces, and rougher surfaces had higher monoclinic contents than untreated surfaces. Multiple firings could be performed if necessary, but the fracture probability could increase after multiple firings for rougher surfaces.

Implant-retained auricular prosthesis.

Auricular defects may result from congenital malformations, injuries from motor vehicle crashes, trauma, or tumor resections. An auricular prosthesis was fabricated for a patient who had an injury from a motor vehicle crash. Extraoral implants and bar-and-clip retention for the proper connection of the auricular prosthesis to implant were used. This prosthesis was acceptable to the patient because of excellent support, retentive abilities, and the patients appearance.

Implant-retained nasal prosthesis

Malignant tumors of the nose occasionally require rhinectomy. Facial defects can cause not only functional problems but also some serious physchological problems that could cause the individual to avoid social contact. In view of this, the first aim of maxillofacial rehabilitation should be solving esthetic problems. Implant retained prostheses can give good esthetic results. Predictable biomechanical retention of nasal prostheses can be achieved using osseointegrated implants and intra-oral and craniofacial implants have been used previously. These prostheses are tissue compatible, simple in design and easy to place, can be worn independently of spectacles and in the majority of cases can be provided soon after surgical excision. In this case report, a nasal prosthesis was fabricated for a patient who lost his nose due to the basal cell carcinoma. Extra-oral implants and magnet retention for the proper connection of the nasal prosthesis were used. This prosthesis was acceptable for the patient because of excellent support, retentive abilities and the patient′s appearance.

Microleakage of different dowel systems luted with resin cements

Aims: The purpose of this study was to compare microleakage of dowel systems: Stainless steel dowel system (SSD), resin-supported polyethylene fiber dowels (RSPFD), Zirconia dowels (ZD) and glass fiber dowels (GFD) luted with two different resin cements. Materials and Methods: The root canals of 96 teeth were restored and two resin cements (Multilink Automix and Clearfil Esthetic cement) were used in cementation procedure. Using the computerized fluid filtration method, microleakage of the specimens was measured at 1 week, and 6 months. Results: The data indicated that the microleakage values varied according to the luting cement used (P < 0.05). The initial microleakage of ParaPost was similar with the other dowel systems, but this microleakage increased over time (P < 0.05). In contrast; microleakage of Ribbond, Cosmopost and Superpost dowels remained constant (P > 0.05). Conclusion: Esthetic dowels tested exhibited less microleakage compared to stainless steel dowel system. Statistically, Multilink Automix cement showed higher microleakage than Clearfil Esthetic cement.

Bond strengths of two ceramic laminate systems to bleached enamel

Abstract The aim of this study was to evaluate the microtensile bond strengths of ceramic laminate veneers bonded to bleached and non‐bleached enamel. Ninety‐six extracted maxillary central incisors were divided into two groups of 48 specimens each, bleached group and non‐bleached group. After bleaching, teeth were prepared to accommodate veneers of equal thickness. Two ceramic systems, Cerec 3 and IPS Empress 2, were used for restoration. Each of the two ceramic groups was luted with Variolink 2 and RelyX veneer cement. Specimens were then subjected to tensile forces. The bond strength values were analysed with two‐way analysis of variance and Tukey honestly significant difference tests. Microtensile bond strength significantly reduced after bleaching procedure (p<0·05). Variolink 2 resin cement showed higher bonding strength than RelyX veneer cement (p<0·05). The results of this in vitro study suggest that the bleaching procedure is an important factor on the bonding effectiveness of ceramic laminate veneers.

Effect of polymerisation techniques on residual monomer amount released from different acrylic resins

Abstract The purpose of this study was to investigate the influence of different polymerisation methods (heat, auto-, injection moulding and microwave) with curing processes (conventional, short- and long-term terminal boiled heat polymerisation and room temperature polymerisation) in combination with varied water storage periods (24 h, 7 and 30 days) on the residual methyl methacrylate (MMA) contents of different dental acrylic resins. Twelve discs were fabricated for each denture base material. Specimens were immersed immediately in separate light proof glass bottles containing 20 mL 75% ethanol and 25% deionised water. Residual monomer (MMA) which eluted from acrylic resins was analysed with high performance liquid chromatography. Data were analysed by two-way analysis of variance and Tukey honestly significant difference tests. The MMA monomer amount eluted from autopolymerised acrylic resin groups (p<0·01) was higher than that from the other groups. Microwave polymerised acrylic resin showed the lowest residual monomer amount compared to the other acrylic resins (p<.01).