Gurel Pekkan

Evaluation of shear and tensile bond strength between dentin and ceramics using dual-polymerizing resin cements.

STATEMENT OF PROBLEM The applications of dual-polymerizing resin cements for all-ceramic restorations have considerably increased. For a successful clinical outcome, the luting agent should have high bond strength, not only to the ceramic surface, but also to the tooth surface. PURPOSE The purpose of this study was to examine shear (S) and tensile (T) bond strengths between 2 all-ceramic systems and human dentin using 3 dual-polymerizing resin cements. MATERIAL AND METHODS The buccal surfaces of 120 freshly extracted human third molars were ground flat, parallel to the long axis. Sixty specimens were prepared from each of 2 all-ceramic systems (IPS Empress 2 (E) and Cergo Pressable Ceramic (C)). Twenty specimens were luted with each of the following resin cements: Nexus 2 (N) with Self-Etch Primer, Duo-Link (D), and Variolink II (V), with their respective bonding systems. All specimens were immersed in water at 37 degrees C for 1 week, before being thermal cycled for 500 cycles in 5 degrees C and 55 degrees C water. Shear (S) and tensile (T) bond strength tests were applied to 10 specimens from each group. Fractured surfaces were inspected by scanning electron microscopy (SEM). Statistical analyses were performed using nonparametric 1-way ANOVA (Kruskal-Wallis) followed by Duncans multiple range tests for post hoc comparison and Mann-Whitney U test for 2 ceramic systems (alpha=.05). RESULTS Significant differences were observed in shear and tensile bond strength values of the adhesive systems used (P<.05). Duo-Link showed the highest mean bond strength values, whereas Nexus 2 revealed lower shear and tensile bond strength values. Fracture modes were hybrid at the dentin interface and/or cohesive in dentin. CONCLUSIONS Cementing agents/adhesive systems may influence the bond to dental hard tissues. Dual-polymerizing activators may have a negative effect on polymerization of the bonding agent.

Comparative audiometric evaluation of temporomandibular disorder patients with otological symptoms

OBJECTIVES The purpose of this study was to assess the audiological status of temporomandibular disorder (TMD) patients with otological symptoms and to make comparisons with that of a control group of subjects without TMD and otological symptoms. METHODS 25 TMD patients with otological symptoms and 20 age and gender matched controls, 45 subjects in total, were included in the study. All subjects underwent a series of audiological tests that included pure-tone audiometry, impedance test and reflex tympanometry. The audiological parameters recorded in the two groups were compared statistically by means of unpaired t tests and corrected according to Bonferroni in the case of repeated tests. RESULTS The pure-tone thresholds at frequencies 125, 250, 500Hz, and 6kHz showed significant differences between the TMD patients and control subjects after the Bonferroni correction (p<0.007). Compliance peaks demonstrated significant differences when the TMD and control groups were compared (p<0.05). CONCLUSIONS The findings indicate that TMD patients with otological complaints have hearing impairment at low frequencies and also perhaps, at high frequencies.

Rehabilitation of an Edentulous Cleft Lip and Palate Patient With a Soft Palate Defect Using a Bar-Retained, Implant-Supported Speech-Aid Prosthesis: A Clinical Report

Prosthetic rehabilitation of an edentulous cleft lip and palate patient with a combined hard and soft palate defect is a great challenge, due to the lack of retention of the obturator prosthesis as a result of its weight and the inability to obtain a border seal. Dental implants improve the retention, stability, and occlusal function of prostheses when used in carefully selected cleft lip and palate cases. This clinical report presents an edentulous unilateral cleft lip and palate patient who has hard and soft palate defects and an atrophied maxilla, treated with an implant-supported speech-aid prosthesis.

Comparative radiopacity of ceramics and metals with human and bovine dental tissues

STATEMENT OF PROBLEM Ceramics should be radiopaque enough to be seen on radiographs and to be distinguishable from tooth structures. Information on the radiopacity of different ceramics used in restorative dentistry is limited. PURPOSE The purpose of this study was to investigate the radiopacity of ceramics in comparison with human and bovine dental hard tissues and metals. MATERIAL AND METHODS A total of 128 disk-shaped specimens, 6 × 1 mm (n=8), were prepared from dental ceramic materials and metals. The optical densities of each material, along with 2 tooth sections (canine and molar teeth), bovine dentin and enamel specimens, and 2 different aluminum step wedges, were measured from radiographic images using a transmission densitometer. The optical densities of the specimens were used to determine the equivalent aluminum thicknesses. The data were analyzed by nonparametric 1-way ANOVA (Kruskal-Wallis) and Student-Newman-Keuls multiple range tests for post hoc comparison (α=.05). RESULTS Among ceramic materials, Cercon Zirconia had the highest and the Cergo Pressable Ceramic had the lowest radiopacity values. Cergo Pressable Ceramic, Noritake Super Porcelain EX3 dentin, IPS Empress e.max Press, Cercon Kiss dentin, IPS Empress 2, Cercon Ceram dentin, bovine dentin, human canine, and molar tooth dentin radiopacity measurements were not significantly different. The radiopacity measurements of In-Ceram Alumina, In-Ceram Spinell, Celay Alumina, Titanium alloy (Ti-6Al-4V), Celay Zirconia, In-Ceram Zirconia, NiCr alloy, Wieland Zirconia, Cercon Zirconia, and 22-carat gold were significantly higher than that of bovine enamel (P<.05). CONCLUSIONS Significant differences in radiopacity were found among ceramic materials, when compared to metals, bovine enamel and human and bovine dentin. Cercon and Wieland Zirconia had high radiopacity values, which were similar to metals.

Saddle nose deformity, palatal perforation and truncus arteriosus in a patient with Crohn's disease.

Crohns disease (CD) is a chronic granulomatous inflammatory bowel disease which may also involve the extraintestinal organs such as joints, liver, skin and perianal tissue. Involvement of the nasal cavity is quite rare in CD. This case report presents a 28-year-old girl with CD and saddle nose deformity, alar collapse and palatal perforation as extraintestinal manifestations of the disease in addition to persistent truncus arteriosus-type 4.

Comparative radiopacity of conventional and full-contour Y-TZP ceramics.

The purpose of this study was to evaluate the radiopacity of different yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramics used in the fabrication of fixed dental prostheses. Disk-shaped specimens (N=120, n=30 per group) were fabricated with thicknesses of 0.3, 0.5, and 1 mm from the following four Y-TZP ceramics: Cercon ht (Degudent) (CZ), Prettau (Zirkonzahn) (ZZ), Alliance (Kuraray Noritake Dental) (NA), and Ice Zirkon (Zirkonzahn) (ICE). The optical densities of each material were measured from radiographic images, and each material (N=1) were characterized by using XRD and SEM. The results were analyzed with oneway analysis of variance and the Tukey-Kramer test (α=0.05). In the case of the ICE and NA specimens, the radiopacity significantly differed with thickness (p<0.05). However, the radiopacities of 0.5- and 0.3-mm-thick CZ and ZZ specimens were not significantly different (p>0.05). Full-contour Y-TZP materials have higher radiopacities than those of the conventional Y-TZP materials in decreased thicknesses.