Ebru Cal

Effects of surface-finishing protocols on the roughness, color change, and translucency of different ceramic systems.

STATEMENT OF PROBLEM Surface-finishing protocols have a mechanical impact on ceramic surfaces that could eventually affect surface topography and light scattering. An optimum protocol is needed to avoid damaging the optical properties of ceramics. PURPOSE The purpose of this study was to determine the effects of different surface-finishing protocols on the surface roughness, color change, and translucency of ceramic and metal ceramic restorations. MATERIAL AND METHODS Standardized disk-shaped specimens (1.5 × 10 mm, n=128) were fabricated from 3 different ceramic core materials (aluminum oxide [Al2O3]-AL, zirconium oxide [ZrO2]-ZR, lithium disilicate [Li2Si2O5]-LIT), veneered (V) with dentin ceramics (n=32 per group), and placed in the following groups: ALV, ZRV, and LITV. The metal ceramic group acted as the control (n=32). Four different surface-finishing methods were tested. Airborne-particle abrasion with 50 μm Al2O3, polishing with adjustment kit, polishing with adjustment kit plus diamond polishing paste, and autoglazing (n=8 subgroup) were applied on the veneering ceramics. The specimens were analyzed with a profilometer for surface roughness, and color change and translucency were measured with a clinical spectrophotometer. Statistical analyses were performed with 1-way ANOVA and the Tukey honest significant difference tests (α=.05). RESULTS Specimens treated with the airborne particle abrasion method showed significantly higher mean profilometer for surface roughness values in all groups (P<.05). The polishing with adjustment kit and autoglazing methods revealed statistically similar surface roughness values in all groups (P>.05). With the diamond polishing paste method, lower surface roughness values were achieved in the ZRV and metal ceramic groups acted as the control groups. Different surface-finishing methods affected the color change of the ceramic systems, except for ZRV. Surface-finishing protocols significantly affected the translucency values of the ALV, LITV, and metal ceramic groups (P<.05). CONCLUSIONS No single surface-finishing protocol can be recommended to obtain the smoothest surface and the least color change without affecting translucency for the ceramics tested. The airborne-particle abrasion protocol created rougher surfaces and decreased translucency, and color change in zirconia was not affected by the finishing protocols.

Bond strength of glass-ceramics on the fluorosed enamel surfaces.

OBJECTIVES Effect of different adhesive luting systems on the shear bond strength of IPS Empress 2 ceramic restorations to fluorosed enamel surface was investigated. METHODS Forty-eight ceramic discs (2 mm x 3 mm; IPS Empress 2) were fabricated. Twenty-four non-carious extracted human molar teeth with fluorosis and 24 without fluorosis were cleaned with pumice using a plastic brush and then they were divided into two main groups. The IPS Empress 2 ceramic discs were luted to the teeth of four subgroups with two different adhesive luting systems, Variolink 2/Excite DSC (etch-and-rinse) and Clearfil Esthetic Cement/ED Primer II (self-etch), thermocycling was performed 5000 times. Shear bond strengths were tested using Shimadzu Universal Testing Machine until failure. An optical microscope and image analyzer were used at 10x and 1000x magnification to analyze the surfaces for adhesive, cohesive and mixed failure percentages. Data was analyzed with one-way ANOVA and Tukey test at a significance level of p<0.05. RESULTS Mean shear bond strength data of the groups in MPa were; Variolink 2/Excite DSC on fluorosed enamel: 18.3+/-3.08, Variolink 2/Excite DSC on non-fluorosed enamel: 18.79+/-2.65, Clearfil Esthetic Cement/ED Primer II on fluorosed enamel: 8.43+/-2.45, Clearfil Esthetic Cement/ED Primer II on non-fluorosed enamel: 13.53+/-1.68. Mixed failure was the most prevalent type of failure in moderate fluorosed and non-fluorosed teeth with etch-and-rinse dentin bonding system, and in fluorosed teeth with self-etch dentin bonding system. CONCLUSIONS The use of an etch-and-rinse adhesive luting procedure produced higher bond strengths of glass-ceramics bonded to fluorosed and non-fluorosed enamel surfaces than the self-etch bonding system.

Oral health-related quality of life among institutionalized patients after dental rehabilitation

The aim of the present study was to determine the changes in oral health‐related quality of life before and 3 months after dental rehabilitation among geriatric patients residing in a state‐owned nursing home, using the General Oral Health Assessment Index (GOHAI).

Effects of New Generation All-Ceramic and Provisional Materials on Fibroblast Cells: Cytotoxicity of Dental Materials

PURPOSE The purpose of this in vitro study was to evaluate the cytotoxic and apoptotic effects of seven new-generation all-ceramic materials for CAD/CAM (Lava Ultimate [LU], VITA Mark II [VM], InCoris TZI [IC], IPS e.max CAD [EM], VITA Suprinity [VS], Cerasmart [CS], IPS Empress CAD [EC]) and six provisional materials (Protemp 4 [PT], Telio CAD [TC], CAD-Temp [CT], Telio Lab [TL], Temdent Classic [TD], Telio CS C&B [TS]) on L929 mouse fibroblast cells. MATERIALS AND METHODS 24 disc-shaped specimens (∅ = 5 mm, h = 2 mm) were prepared from each test material. Medium extracts were collected at the 1st, 3rd, and 7th days for each group and tested using the L929 cell line. Cytotoxicity was evaluated using XTT assay, and apoptosis was determined by Annexin-V/PI staining. Data were analyzed using one-way ANOVA, Tukeys multiple comparison tests at a significance level of p < 0.05. RESULTS The cell viability results among all-ceramic material groups after the 1st and 7th days of incubation periods showed statistically significant differences (p < 0.05). There were significant differences within the ceramic groups in different incubation periods regarding apoptosis rate (p < 0.05). Throughout the entire test period, LU and VM from the CAD/CAM all-ceramic materials and PT and TC from the provisional restoration materials showed cell viability higher than 90%. EC and TD showed the lowest cell viability and highest apoptosis rates in their own groups. For the provisional materials, there were significant differences in cell viability and apoptosis rate in all the incubation periods for each material (p < 0.05). CONCLUSIONS Although some new-generation CAD/CAM and provisional restoration materials display slight cytotoxicity values, the results are still within the reliable range, and they can safely be used in clinical conditions.

Color change of CAD-CAM materials and composite resin cements after thermocycling

Statement of problem. The color of resin cements and computer‐aided‐design and computer‐aided‐manufacturing (CAD‐CAM) restorations may change with aging. Purpose. The purpose of this in vitro study was to analyze the influence of thermocycling on the color of CAD‐CAM materials with underlying resin cement. Material and methods. Seven different CAD‐CAM materials, composite resins and glass‐ceramics were cut into 0.7‐mm and 1.2‐mm thicknesses (n=10) and cemented with a dual‐polymerizing resin cement, a light‐polymerizing resin cement, and a preheated composite resin (N=420). Color values were measured by using spectrophotometry. Specimens were subjected to thermocycling (5°C and 55°C; 5000 cycles). The measured color difference (&Dgr;E) data were analyzed by using descriptive statistics. Normality of data distribution was tested by using the Kolmogorov‐Smirnov test. Three‐way and 1‐way ANOVA followed by the Scheffé post hoc test and unpaired 2‐sample Student t test were computed to determine the significant differences among the tested parameters (&agr;=.05). Results. &Dgr;E values were significantly influenced by the CAD‐CAM material (&eegr;p2=0.85, P<.001) and the resin composite cement (&eegr;P2=0.03, P=.003) but were not influenced by thickness (P=.179). Significant interactions were present among thickness, cement, and CAD‐CAM materials (P<.001). Vita Suprinity and GC Cerasmart showed significantly the lowest &Dgr;E values (P<.001). The highest &Dgr;E values were observed for IPS Empress CAD. The dual‐polymerizing resin cement showed significantly lower &Dgr;E values than the preheated composite resin (P=.003). Conclusions. Restoration materials and composite resin cement types used for cementation influence the amount of color change due to aging.

Influence of desensitizing procedures on adhesion of resin cements to dentin

Abstract This study evaluated the effect of two desensitizer agents with different contents and Nd:YAG laser irradiation on the shear bond strength (SBS) of adhesive resin cements to dentin. New treatment options of Nd:YAG laser irradiation and tetracalcium phosphate-containing agent applications were compared with routinely used glutaraldehyde-containing agents. One hundred and twenty human, caries-free premolars were embedded in acrylic resin blocks 2 mm below the cementoenamel junction. Buccal surfaces of the teeth were ground to expose dentin. The specimens were randomly assigned into three different surface treatments (desensitizing agents, Nd:YAG laser) and the control, then into three different adhesive resin cement applications (n = 10). Resin cements (Panavia SA cement (PA), Panavia SA cement with Clearfil Universal Bond (PACU), and Multilink N (MN)) were applied to the conditioned teeth surfaces using Teflon tubes. The specimens were thermocycled (5000 cycles, 5–55 ± 1 °C, dwell time 30 s). The SBS test was performed in all groups. The results were submitted to two-way ANOVA and Tukey HSD tests (p < .05). Further, SEM analysis was performed on the dentin surfaces. SBS values were significantly difference among the surface treatment groups and also among adhesive resin cement groups (p < .05). The specimen cemented with PA showed lower SBS values than PACU- and MN-applied specimens. The highest SBS value was obtained in the Nd:YAG laser group which was cemented with PACU cement. The lowest SBS value was obtained in the control group which was cemented with PA cement. In addition, SEM evaluation revealed that desensitizing agents and Nd:YAG laser occluded dentin tubules.

Radiopacity of Luting Cements as a Potential Factor in Peri-implantitis: An In Vitro Comparative Study

The aim of this study was to establish the radiopacity of cements used in implant-retained fixed partial dentures with respect to implant material, enamel, and dentin. A sample of 10 specimens of 13 different cements, implants, enamel, and dentin were prepared. Radiographs of the specimens and aluminum step wedges were acquired. Mean gray values of specimens were measured using digital imaging software. Kolmogorov-Smirnov and Shapiro-Wilk normality tests and independent t test were used (P = .05). Implantlink Semi, Premier, and Dentotemp had the lowest radiopacity values; GC FujiTemp LT, Multilink Implant, Poly-F Plus, Cavex-Temporary, and Panavia SA showed the highest. Within the limitations of the study, cements containing zinc oxide and ytterbium-trifluoride can be recommended for cementation of implant-retained restorations.

Cytotoxicity of Dental Implants: The Effects of Ultrastructural Elements

PURPOSE In this in vitro study, the purpose was to assess the cytotoxicity profiles of seven commercial dental implant materials by using cell culture methods on an osteoblastic cell line. MATERIALS AND METHODS The microstructure of seven commercial dental implants (each given a letter code) was investigated via scanning electron microscopy and energy-dispersive x-ray analysis. Medium extracts were collected on the first and fifth days for each group and tested using MC3T3-E1 cell line. Cytotoxicity was evaluated with Xcelligance System and XTT reagent, and apoptosis was determined by Annexin-V staining. One-way analysis of variance (ANOVA) and Tukeys multiple range tests were used for statistical analyses. In all tests, P was set as .05. RESULTS ANOVA results disclosed that Ti (P = .001), Na (P = .001), Ca (P = .019), Al (P = .024), and P (P = .020) amounts were significantly different between test materials. Cytotoxicity and apoptosis analyses revealed that implant materials (C) and (E) were the materials with the lowest cell vitality and the highest apoptosis rates among the test materials. Phosphorus was the only element that presented the highest amount in C and E (14.23% and 12.29%, respectively) compared with the other implant materials tested. (F) and (G) had favorable results for all experiments. CONCLUSION The results suggest that pure dental implant materials with a lower number of additional elements may possess fewer cytotoxic effects than the other implant materials tested in this study.

Glass–ceramics bonding in geriatric patients: comparison with young teeth

OBJECTIVE The aim of the study was to assess whether in geriatric patients, the shear bond strength (SBS) of glass-ceramics differed when compared to young controls. BACKGROUND In the need of aesthetic restorations for geriatric patients, reliable bonding of glass-ceramics should be accomplished; however, glass-ceramics bonding on aged tooth structures is still unclear. MATERIALS AND METHODS Sixty extracted molars from young and geriatric patients [18-25 (Y), and 65-80 (O)] were cut buccolingually to prepare enamel (E) and dentin (D) surfaces. Both surfaces were randomly divided into three groups according to the resin cements: Variolink II (V); Superbond (S); and Clearfil Esthetic Cement (C) (n = 10). Disc-shaped glass-ceramics (IPS E-max Press) (n = 120) were prepared. Specimens were bonded and subjected to thermocycling. SBS test was performed using a universal testing machine (0.5 mm/min). After debonding, the surfaces were examined using stereomicroscope and scanning electron microscope. Data were statistically analysed with Kolmogorov-Smirnov, Levene, anova and Bonferroni tests (p = 0.05). RESULTS There were no significant differences between the old and young teeth surfaces. V showed the highest SBS [MPa(SD)] on both enamel and dentin [36.7 (6.5) (YE), 23.2 (13.2) (YD), 32.1 (16.2) (OE), 25.5 (8.6) (OD), respectively]. Significant differences were observed between resin cements (p < 0.05). The failure types were 43% adhesive between tooth and cement, 48% mix, 9% adhesive between cement and ceramic, regardless of cement type. CONCLUSION In geriatric patients, the shear bond strength of glass-ceramics did not differ when compared to that of young controls. On the dentin surface, etch-rinse resin cements appear to be more appropriate for glass-ceramics bonding.

Obstructive sleep apnoea and the need for its introduction into dental curricula.

Obstructive sleep apnoea (OSA) is a major health problem which causes blood oxygen desaturation that may initiate a cascade of events via inflammatory cytokines and adrenocorticotrophic hormone that may have impact upon quality of life and lead to potential life-threatening events. Even though OSA affects an increasing number of individuals, the role of dental practitioners in recognition, screening and management has not developed accordingly. The goal of this article was to provide updated information to dental practitioners on pathophysiology, consequences and treatment options of OSA with a focused discussion on oral appliance (OA) therapy, as this topic is not routinely included in current dental curricula of many dental schools. Additionally, we present a template dental curriculum for predoctoral and/or postdoctoral students in education regarding sleep disordered breathing.