Bulem Yuzugullu

Surface roughness and bond strengths of glass-infiltrated alumina-ceramics prepared using various surface treatments

OBJECTIVES To compare and evaluate effects of CO(2) laser and conventional surface treatments on surface roughness and shear bond strengths of glass-infiltrated alumina-ceramics to dentin. METHODS One hundred fifty ceramic discs of In-Ceram Spinell, In-Ceram Alumina and In-Ceram Zirconia (n=50) were prepared. Specimens which were divided into 5 groups (n=10) were untreated (control group), sandblasted, airborne particle abraded, etched with 9.6% hydrofluoric acid or irradiated with CO(2) laser. Scanning electron microscope was used at 1000x magnification for qualitative examination. Following surface roughness (Ra) determination by profilometry, discs were cemented on extracted-human-molar teeth. Cemented specimens were stored in distilled water at 37 degrees C for 1 week. Shear bond strength (MPa) test was performed using a universal testing machine at a crosshead speed of 1mm/min. Statistical comparisons were made with Wilcoxon signed ranked test, Kruskall Wallis test and Spearmans correlation coefficient. RESULTS All surface treatments produced rougher surfaces than the untreated groups of all ceramics (P<.05). Sandblasting demonstrated a rougher surface on In-Ceram Spinell than In-Ceram Alumina and In-Ceram Zirconia (P<.05). While CO(2) laser irradiation showed significantly higher bond strength for In-Ceram Spinell (P<.05), both airborne particle abrasion and CO(2) laser irradiation showed higher bond strengths for In-Ceram Zirconia (P<.05). Airborne particle abrasion demonstrated higher bond strength for In-Ceram Alumina and In-Ceram Zirconia (P<.05). No significant relationship was determined between surface roughness (Ra) and shear bond strength values (MPa) among ceramic groups. CONCLUSIONS Sandblasting is an effective surface treatment for roughening surfaces of In-Ceram Spinell. Although CO(2) laser irradiation does not increase surface roughness, it reveals the highest bond strength.

Radiomorphometric indices and their relation to alveolar bone loss in completely edentulous Turkish patients: A retrospective study

STATEMENT OF PROBLEM In edentulous patients, alveolar bone loss is a critical factor that affects denture retention, stability, and masticatory function. In addition to their use for the assessment of bone quality, panoramic radiomorphometric indices have been used to observe signs of bone resorption. Currently, there is no published data on the possible relationships between bone loss, radiomorphometric indices, and edentulism. PURPOSE The purpose of this study was to investigate the influence of age and gender on the mandibular cortical index, panoramic mandibular index, and mandibular cortical width, as well as alveolar bone loss and bone height, using panoramic radiographs of patients having been edentulous for more than 2 years. MATERIAL AND METHODS Panoramic radiographs of 94 edentulous patients (41.5% men and 58.5% women) were assessed. In addition to gender and age, the mandibular cortical index (normal cortex, mild or severe erosions on endosteal margin of the mandible), panoramic mandibular index, mandibular cortical width at the mental foramen region, alveolar bone loss, and bone heights of the premolar and molar regions of the mandible were recorded. Statistical comparisons were performed using chi-square, Mann-Whitney U, Kruskal-Wallis, and 2-way ANOVA tests (alpha=.05). RESULTS Mild erosions on the endosteal margin of the mandible were more frequently seen in age groups of <or=60, and severe erosions on the endosteal margin of the mandible were more frequently observed in age groups of >60 in women (P<.001). While the mean values of the mandibular cortical width were stable as age increased in men, the mean mandibular cortical width values decreased significantly with age in women (P<.01). The panoramic mandibular index, alveolar bone loss, and bone heights were not affected by age or gender. CONCLUSIONS Severe erosions on the endosteal margin of the mandible are seen more frequently in women over 60 years in age. While mean mandibular cortical width values are stable in men over 60 years, mean mandibular cortical width values decrease significantly in women of the same age group.

Diametral Tensile and Compressive Strengths of Several Types of Core Materials

PURPOSE Compressive and diametral tensile strengths (DTSs) of core materials are thought to be important, because cores usually replace a large bulk of tooth structure and should provide sufficient strength to resist intraoral tensile and compressive forces. This study was undertaken to compare the mechanical properties of materials used for direct core foundations. MATERIAL AND METHODS The differences between the compressive and DTSs of six core materials, including Duralloy (high-copper amalgam), Grandio (visible light-cured nanohybrid resin composite), Admira (organically modified ceramic), Filtek P60 (packable composite resin), Rebilda DC (dual-cure adhesive core material), and Argion Molar (silver-reinforced glass ionomer cement), were tested. A total of 120 specimens, half for the compressive strength (CS) test (6 mm in height, 4 mm in diameter) and the other half for the DTS test (6 mm in diameter, 3 mm in thickness), were prepared. The specimens were stored at room temperature in distilled water for 7 days. The Lloyd testing machine was used to load the specimens at a crosshead speed 0.5 cm/min, and the strength values were determined in MPa. RESULTS The compressive and DTS test values (in MPa), respectively, of the materials were: Admira (361, 44); Filtek P60 (331, 55); Grandio (294, 53); Rebilda DC (279, 42); Duralloy (184, 40); and Argion Molar (107, 9). Kruskal-Wallis test was computed, and multiple comparisons test discerned many differences among materials (p < 0.05). CONCLUSION Packable composite resin (Filtek P60), visible light cured nanohybrid resin composite (Grandio), and organically-modified ceramic (Admira) had higher compressive and DTS values than the other materials.

Effect of bleaching on staining susceptibility of resin composite restorative materials.

STATEMENT OF THE PROBLEM Effect of bleaching procedures on staining susceptibility of resin restorative materials is still questionable. PURPOSE The aim of this study was to evaluate the staining susceptibility of restorative materials bleached with 20% carbamide peroxide home bleaching agent and subsequently immersed in coffee and tea. MATERIALS AND METHODS Forty-two disk-shaped specimens were fabricated for each of the resin composites (Filtek Supreme XT [3M ESPE, St. Paul, MN, USA], Ceram-X Mono [Dentsply, Konstanz, Germany], and Aelite All Purpose Body [BISCO, Inc., Shaumburg, IL, USA]). The baseline color values were measured with a spectrophotometer. The specimens of each restorative material were randomly divided into two groups (N = 21). While the first group specimens were stored in distilled water (nonbleaching group-control), bleaching agent (Opalescence PF 20% [Ultradent Poducts, South Jordan, UT, USA]) was applied on the top surface of each specimen of the second group (bleaching group). After color change values were measured, the specimens were randomly divided into three subgroups (N = 7) according to the staining solutions. The color change values (DeltaE*ab) were calculated and the data were subjected to analysis of variance. Statistical significance was declared if the p value was 0.05 or less. RESULTS There was no statistically significant difference within each restorative materials DeltaE*ab values after bleaching (p = 0.714). Also, the staining solutions did not cause a statistically significant difference between DeltaE*ab values of bleaching compared with nonbleaching groups (p = 0.146). Significant interaction was found only between restorative materials and staining solutions (p = 0.000). CONCLUSION Bleaching of the tested resin composites did not increase their susceptibility to extrinsic staining in vitro. CLINICAL SIGNIFICANCE Bleaching did not affect staining susceptibility of the tested resin composite restorative materials. (J Esthet Restor Dent 21:407-415, 2009).

Effects of shade tab arrangement on the repeatability and accuracy of shade selection

STATEMENT OF PROBLEM Appropriate and repeatable shade matching using visual shade selection remains a challenge for the restorative dentist. PURPOSE The purpose of this study was to evaluate the effect of different arrangements of a shade guide on the repeatability and accuracy of visual shade selection by restorative dentists. MATERIAL AND METHODS Three Vitapan Classical shade guides were used for shade selection. Seven shade tabs from one shade guide were used as target shades for the testing (A1, A4, B2, B3, C2, C4, and D3); the other 2 guides were used for shade selection by the subjects. One shade guide was arranged according to hue and chroma and the second was arranged according to value. Thirteen male and 22 female restorative dentists were asked to match the target shades using shade guide tabs arranged in the 2 different orders. The sessions were performed twice with each guide in a viewing booth. Collected data were analyzed with Fishers exact test to compare the accuracy and repeatability of the shade selection (α=.05). RESULTS There were no significant differences observed in the accuracy or repeatability of the shade selection results obtained with the 2 different arrangements. When the hue/chroma-ordered shade guide was used, 58% of the shade selections were accurate. This ratio was 57.6% when the value-ordered shade guide was used. The observers repeated 55.5% of the selections accurately with the hue/chroma-ordered shade guide and 54.3% with the value-ordered shade guide. CONCLUSIONS The accuracy and repeatability of shade selections by restorative dentists were similar when different arrangements (hue/chroma-ordered and value-ordered) of the Vitapan Classical shade guide were used.

Bond strength of veneer ceramic and zirconia cores with different surface modifications after microwave sintering

PURPOSE To evaluate the effects of surface treatments on shear bond strength (SBS) between microwave and conventionally sintered zirconia core/veneers. MATERIALS AND METHODS 96 disc shaped Noritake Alliance zirconia specimens were fabricated using YenaDent CAM unit and were divided in 2 groups with respect to microwave or conventional methods (n=48/group). Surface roughness (Ra) evaluation was made with a profilometer on randomly selected microwave (n=10) and conventionally sintered (n=10) cores. Specimens were then assessed into 4 subgroups according to surface treatments applied (n=12/group). Groups for microwave (M) and conventionally (C) sintered core specimens were as follows; MC,CC: untreated (control group), M1,C1:Al2O3 sandblasting, M2,C2:liner, M3,C3:Al2O3 sandblasting followed by liner. Veneer ceramic was fired on zirconia cores and specimens were thermocycled (6000 cycles between 5°-55℃). All specimens were subjected to SBS test using a universal testing machine at 0.5 mm/min, failure were evaluated under an optical microscope. Data were statistically analyzed using Shapiro Wilk, Levene, Post-hoc Tukey HSD and Students t tests, Two-Way-Variance-Analysis and One-Way-Variance-Analysis (α=.05). RESULTS Conventionally sintered specimens (1.06 ± 0.32 µm) showed rougher surfaces compared to microwave sintered ones (0.76 ± 0.32 µm)(P=.046), however, no correlation was found between SBS and surface roughness (r=-0.109, P=.658). The statistical comparison of the shear bond strengths of C3 and C1 group (P=.015); CC and MC group (P=.004) and C3 and M3 group presented statistically higher (P=.005) values. While adhesive failure was not seen in any of the groups, cohesive and combined patterns were seen in all groups. CONCLUSION Based on the results of this in-vitro study, Al2O3- sandblasting followed by liner application on conventionally sintered zirconia cores may be preferred to enhance bond strength.

Dental Anxiety and Fear: : Relationship with Oral Health Behavior in a Turkish Population

The aim of this study was to assess fear and anxiety in dental patients. Five hundred patients were evaluated using the Modified Dental Anxiety Scale and the Dental Fear Scale, along with a questionnaire. Oral health status was assessed using the Decayed, Missing, and Filled Teeth (DMFT)/Decayed, Missing, and Filled Surfaces (DMFS) index. Statistic al analysis was performed (P < .05). Sex significantly affected dental anxiety (P < .05), and sex, marital status, having children, and time elapsed since last visit to clinician affected dental fear (P < .05). DMFT/DMFS scores were not related to dental anxiety or fear (P > .05). Female sex alone was a significant predictor of dental anxiety; female sex, adulthood, marriage, having children, and time passed since last visit to a clinician are significant predictors of fear.

Correlation between residual ridge resorption and radiomorphometric indices

OBJECTIVES The study evaluated the relationship between residual ridge resorption (RRR) and radiomorphometric indices, including mandibular cortical index (MCI), mandibular cortical width (MCW) and panoramic mandibular index (PMI), along with demographic factors. MATERIAL AND METHODS Panoramic radiographs of 1863 patients over 20 years of age were assessed. Gender, age and dental status of each patient were recorded. Relationships between RRR and demographic factors and radiomorphometric indices were evaluated using chi-square and Fishers exact tests with level of significance of p = 0.05. RESULTS Residual ridge resorption was not affected by gender (p > 0.05), but was more frequently seen in patients over the age of 50 compared with those below 49 years of age (p < 0.001). RRR was significantly associated with edentulism (p < 0.001) and with severe erosions of endosteal margin of mandible (p < 0.05). RRR was more frequently seen in patients with PMI below 0.30 (p < 0.001) and with MCW below 3 mm in 50- to 69-year-old age group (p < 0.001). CONCLUSIONS Patients younger than 50 years of age who demonstrate severe erosions of endosteal margin of mandible and have MCW < 3 mm and PMI < 0.30 appear to be suitable candidates for early implant placement or for maintaining roots or natural teeth to preserve bone, regardless of gender.

The Effect of Different Polishing Sequences on the Adhesion of Streptococcus mutans to Feldspathic Porcelain

The aim of this research was to determine whether extra-oral surface treatments on feldspathic porcelain surfaces influence initial adhesion of Streptococcus mutans. Ninety-six porcelain specimen discs were fabricated and divided into six equal groups according to surface treatment: fine-grit diamond polishing (Group 1); self-glazing (Group 2); overglazing (Group 3); overglazing followed by a finishing procedure and then overglazing (Group 4); Pearl Surface polishing (Group 5); and Diamond Twist SCLTM polishing (Group 6). Surface roughness and hydrophobicity were assessed. An S. mutans suspension was incubated on each specimen group and evaluated. A one-way analysis of variance, post-hoc Tukey honestly significantly different test, Friedman test, and t-test were used for statistical analysis. Group 1 showed the highest surface roughness (p < 0.001) and bacterial adhesion (p < 0.05). Groups 5 and 6 specimen surfaces presented significantly higher contact angles (p < 0.05). Group 1 had the highest S. mutans adhesion, followed by Groups 3, 5, 6, 2, and 4 (p < 0.05). Reglazing after grinding may therefore decrease bacterial adhesion beneficially.

Effect of different denture cleansers on surface roughness and microhardness of artificial denture teeth.

PURPOSE The aim of this study was to compare the effects of different denture cleansers on the surface roughness and microhardness of various types of posterior denture teeth. MATERIALS AND METHODS 168 artificial tooth specimens were divided into the following four subgroups (n=42): SR Orthotyp PE (polymethylmethacrylate); SR Orthosit PE (Isosit); SR Postaris DCL (double cross-linked); and SR Phonares II (nanohybrid composite). The specimens were further divided according to the type of the denture cleanser (Corega Tabs (sodium perborate), sodium hypochlorite (NaOCl), and distilled water (control) (n=14)) and immersed in the cleanser to simulate a 180-day immersion period, after which the surface roughness and microhardness were tested. The data were analyzed using the Kruskal–Wallis test, Conovers nonparametric multiple comparison test, and Spearmans rank correlation analysis (P<.05). RESULTS A comparison among the denture cleanser groups showed that NaOCl caused significantly higher roughness values on SR Orthotyp PE specimens when compared with the other artificial teeth (P<.001). Furthermore, Corega Tabs resulted in higher microhardness values in SR Orthotyp PE specimens than distilled water and NaOCl (P<.005). The microhardness values decreased significantly from distilled water, NaOCl, to Corega Tabs for SR Orthosit PE specimens (P<.001). SR Postaris DLC specimens showed increased microhardness when immersed in distilled water or NaOCl when compared with immersion in Corega Tabs (P<.003). No correlation was found between surface roughness and microhardness (r=0.104, P=.178). CONCLUSION NaOCl and Corega Tabs affected the surface roughness and microhardness of all artificial denture teeth except for the new generation nanohybrid composite teeth.