Fatigue behavior of implant-supported cantilevered prostheses in recently introduced CAD-CAM polymers: An in vitro study.

STATEMENT OF PROBLEM: Cantilevered complete arch implant-supported prostheses are commonly fabricated from zirconia and more recently from strength gradient zirconia. Different polymer-based materials indicated for definitive fixed prostheses that could be used with additive or subtractive manufacturing have also been marketed recently. However, knowledge on the long-term fatigue behavior of cantilevered implant-supported prostheses made from these polymer-based materials and strength gradient zirconia is lacking. PURPOSE: The purpose of this in vitro study was to evaluate the fatigue behavior of implant-supported cantilevered prostheses of recently introduced computer-aided design and computer-aided manufacturing polymers and zirconia. MATERIAL AND METHODS: A master standard tessellation language file of a 9×11×20-mm specimen with a titanium base (Ti-base) space that represented an implant-supported cantilevered prosthesis was used to fabricate specimens from additively manufactured interim resin (AM), polymethyl methacrylate (SM-PM), nanographene-reinforced polymethyl methacrylate (SM-GR), high-impact polymer composite resin (SM-CR), and strength gradient zirconia (SM-ZR) (n=10). Each specimen was prepared by following the respective manufacturer's recommendations, and Ti-base abutments were cemented with an autopolymerizing luting composite resin. After cementation, the specimens were mounted in a mastication simulator and subjected to 1.2 million loading cycles under 100 N at 1.5 Hz; surviving specimens were subjected to another 1.2 million loading cycles under 200 N at 1.5 Hz. The load was applied to the cantilever extension, 12-mm from the clamp of the mastication simulator. The Kaplan-Meier survival analysis and Cox proportional hazards model were used to evaluate the data (α=.05). RESULTS: Significant differences in survival rate and hazard ratio were observed among materials (P<.001). Among tested materials, SM-ZR had the highest and AM had the lowest survival rate (P≤.031). All materials had a significantly higher hazard ratio than SM-ZR (P≤.011) in the increasing order of SM-GR, SM-PM, SM-CR, and AM. CONCLUSIONS: SM-ZR had the highest survival rate with no failed specimens. Even though most of the tested polymer-based materials failed during cyclic loading, these failures were commonly observed during the second 1.2 million loading cycles with 200 N. All materials had a higher hazard ratio than SM-ZR.

Effect of scan powder and scanning technology on measured deviations of complete-arch implant supported frameworks digitized with industrial and intraoral scanners.

OBJECTIVES: To evaluate the suitability of intraoral scanners (IOSs) to analyze the fabrication trueness of titanium complete-arch implant-supported frameworks by comparing with an industrial-grade scanner and investigate how anti-reflective scan powder affects measured deviations. METHODS: Ten titanium complete-arch implant-supported frameworks were milled from a reference standard tessellation language (STL) file. An industrial-grade blue light scanner (ATOS Core 80 (AT)) and three IOSs (Primescan (PS), TRIOS T3 (T3), and TRIOS T4 (T4)) with (PS-P, T3-P, and T4-P) or without (PS, T3, and T4) anti-reflective scan powder application were used to generate test STL (TSTL) files of the frameworks. Reference STL and TSTLs were imported into a metrology-grade analysis software (Geomagic Control X) and whole surface root mean square (RMS) values were calculated. Another software (Medit Link v 2.4.4) was used to virtually isolate marginal surfaces of all STL files and marginal RMS values were calculated by using the same metrology-grade analysis software. A linear mixed effects model was used to compare the transformed deviations of the scans performed by using each IOS (with or without powder) with the deviations of those performed by using the reference AT scanner within each surface, where a Box-Cox type transformation was used for variance stability. Bonferroni corrected post-hoc tests were used to compare conditions within each IOS (α=0.05). RESULTS: All IOSs had significantly higher whole surface and marginal RMS values than AT, regardless of the condition (P≤.002). However, scan powder application did not affect the whole surface and marginal RMS values in scans of tested IOSs (P≥.054). CONCLUSION: Measured whole surface and marginal deviations in all IOS scans performed with or without the use of scan powder were higher than those in AT scans. The application of anti-reflective scan powder did not affect the deviations in scans of tested IOSs. CLINICAL SIGNIFICANCE: Even though deviations measured in the scans of tested scanners were significantly different than those in the reference scanner, the maximum raw mean difference was 37.33 µm and the maximum raw confidence interval value of estimated differences was 47.88 µm, which can be considered clinically small taking into account the size of the frameworks tested. Therefore, tested intraoral scanners may be feasible to scan prostheses similar to or smaller than tested frameworks for fabrication trueness analysis, which may facilitate potential clinical adjustments.

Comparison of intraoral and laboratory scanners to an industrial-grade scanner while analyzing the fabrication trueness of polymer and titanium complete-arch implant-supported frameworks.

OBJECTIVES: To compare the scans of different intraoral scanners (IOSs) and laboratory scanners (LBSs) to those of an industrial-grade optical scanner by measuring deviations of complete-arch implant-supported frameworks from their virtual design file. MATERIAL AND METHODS: Ten polyetheretherketone (PEEK) and 10 titanium (Ti) complete-arch implant-supported frameworks were milled from a master standard tessellation language (STL) file. An industrial-grade blue light scanner (AT), 2 LBSs (MT and E4), and 3 IOSs (PS, T3, and T4) were used to generate STL files of these frameworks. All STLs were imported into an analysis software (Geomagic Control X) and overall root mean square (RMS) values were calculated. Marginal surfaces of all STL files were then virtually isolated (Medit Link v 2.4.4) and marginal RMS values were calculated. Deviations in scans of tested scanners were compared with those in scans of AT by using a linear mixed effects model (α = 0.05). RESULTS: When the scans of PEEK frameworks were considered, PS and T3 had similar overall RMS to those of AT (p ≥ .076). However, E4 and T4 had higher and MT had lower overall RMS than AT (p ≤ .002) with a maximum estimated mean difference of 13.41 µm. When the scans of Ti frameworks were considered, AT had significantly lower overall RMS than tested scanners (p ≤ .010) with a maximum estimated mean difference of 31.35 µm. Scans of tested scanners led to significantly higher marginal RMS than scans of AT (p ≤ .006) with a maximum estimated mean difference of 53.90 µm for PEEK and 40.50 µm for Ti frameworks. CONCLUSION: Only the PEEK framework scans of PS and T3 led to similar overall deviations to those of AT. However, scans of all tested scanners resulted in higher marginal deviations than those of AT scans. CLINICAL SIGNIFICANCE: Scans performed by using PS and T3 may be alternatives to those of tested reference industrial scanner AT, for the overall fabrication trueness analysis of complete-arch implant-supported PEEK frameworks.

Effect of analysis software program on measured deviations in complete arch, implant-supported framework scans.

STATEMENT OF PROBLEM: Implementation of fabrication trueness analysis by using a recently introduced nonmetrology-grade freeware program may help clinicians and dental laboratory technicians in their routine practice. However, knowledge of the performance of this freeware program when compared with the International Organization for Standardization recommended metrology-grade analysis software program is limited. PURPOSE: The purpose of this in vitro study was to evaluate the effect of an analysis software program on measured deviations in the complete arch, implant-supported framework scans. MATERIAL AND METHODS: A total of 20 complete arch, implant-supported frameworks were fabricated from a master standard tessellation language (STL) file from either polyetheretherketone (PEEK) or titanium (Ti) (n=10). All frameworks were then digitized by using different scanners to generate test STLs. All STL files were imported into a nonmetrology-grade freeware program (Medit Link) and a metrology-grade software program (Geomagic Control X) to measure the overall and marginal deviations of frameworks from the master STL file by using the root mean square (RMS) method. Data were analyzed by using the two 1-sided paired t test procedure, in which 50 µm was considered as the minimal clinically meaningful difference (α=.05). RESULTS: When overall RMS values were considered, the nonmetrology-grade freeware program was not inferior to the metrology-grade software program (P<.05). When marginal RMS values were considered, the nonmetrology-grade freeware program was inferior to the metrology-grade software program only when PEEK frameworks were scanned with an E4 laboratory scanner (P>.05). CONCLUSIONS: The use of the tested nonmetrology-grade freeware program resulted in overall deviation measurements similar to those when a metrology-grade software program was used. The freeware program was inferior when marginal deviations were analyzed on E4 scans of a PEEK framework, which was the only scanner-material pair that led to a significant difference, among the 15 pairs tested.

Effect of cross-polarization filters on the trueness of colors obtained with a single-lens reflex camera, macro lens, and a ring flash.

OBJECTIVE: To investigate the effect of cross-polarization filters on the colors of shade tabs obtained with a digital single-lens reflex (DSLR) camera, macrolens, and a ring flash. MATERIALS AND METHODS: Digital images of four shade tables (1M1, 3L2.5, 3R2.5, and 5M3) from the VITA Toothguide 3D-Master shade guide were taken using a DSLR camera, 100 mm macrolens, and ring flash with two different cross-polarizing filters (Polar_eyes and Filtropolar), and without (Nonpolarizer; n = 7). The CIE L*a*b* color coordinates of digital images were calculated and remeasured with a spectroradiometer (SR). The color differences (ΔE00 ) between the SR and digital images were calculated and analyzed with the two-way analysis of variance (ANOVA) and Tukey HSD test (α = 0.05). RESULTS: ΔE00 values of all test groups were higher than the clinically acceptable threshold (∆E00 > 1.80). While the ∆E00 values of Filtropolar (6.19 ± 0.44) and Polar_eyes (7.82 ± 0.23) groups were significantly higher than the Nonpolarizer (4.69 ± 0.32) for the 1M1 shade tab, ∆E00 value of Polar_eyes (6.23 ± 0.34) was significantly lower than Nonpolarizer (10.71 ± 0.48) group for 5M3 shade tab (p < 0.05). CONCLUSION: The color-matching results of tested digital photography techniques with and without cross-polarization were unacceptable, compared to a spectroradiometer. While digital photography with Polar_eyes cross-polarizing filter has closer results to the reference device for the low-in-value shade table (5M3), for the high-in-value shade table (1M1), improved results were obtained without a cross-polarizing filter. CLINICAL SIGNIFICANCE: The cross-polarization filters are increasingly used in dentistry for tooth color communication with digital photography techniques. However, the digital photography techniques with-without cross-polarization filterers should be improved to obtain clinically acceptable color-matching results.

Comparing the shear bond strength of veneering materials to the PAEKs after surface treatments.

BACKGROUND: This study aimed to evaluate the impact of various surface treatments on the shear bond strength (SBS) of polyetheretherketone (PEEK) and polyetherketoneketone (PEKK) polymers to indirect laboratory composite (ILC) and lithium disilicate ceramic (LDC) veneering materials. METHODS: Polymer specimens (7 × 7x2 mm) were sectioned from PEEK and PEKK discs (N = 294) and randomly allocated to 7 groups (n = 20); untreated (Cnt), plasma (Pls), 98% sulfuric acid (Sa), sandblasting with 110 µm Al2O3 (Sb), tribochemical silica coating with 110 µm silica modified Al2O3 (Tbc), Sb + Sa, Tbc + Sa. Scanning electron microscopy assessments were performed on one sample of each treatment group, and veneering materials were applied to the remaining specimens (n = 10). The specimens were subjected to the SBS test after being soaked in distilled water (24 h, 37 °C). Three-way ANOVA, independent sample t-test, and Tukey HSD test were performed for statistical analyses (α = .05). RESULTS: The surface treatment, polymer, veneering material types, and their interactions were significant on SBS results according to the 3-way ANOVA (p < 0.001). The SBS values of ILC veneered groups were significantly higher than LDC groups, regardless of surface treatment and polymer type (p < 0.05). The highest SBS values were obtained for Sa-applied ILC veneered PEEK (21.55 ± 1.45 MPa) and PEKK (17.04 ± 1.99 MPa) polymer groups (p < 0.05). CONCLUSION: The effect of surface treatment and veneering materials may be significant on the SBS values of PAEKs. Therefore, the application parameters of surface treatments should be more specified for the applied veneering material and polymer type.

Influences of Toothbrushing and Different Toothpastes on the Surface Roughness and Color Stability of Interim Prosthodontic Materials.

The surface properties and color stability of interim crown materials may vary depending on the toothbrushing procedure. This study aimed to investigate the effects of toothbrushing and different toothpastes on the surface roughness (Ra) and color stability of different interim crown materials. Disc-shaped specimens were prepared from four interim crown materials (Tab 2000 (ChPM), Imident (LaPM), Protemp 4 (ChDM), and Telio-CAD (CadPM)). Specimens were divided into four subgroups for the control group (Cnt) and for simulated toothbrushing with distilled water (Dw) or with two different toothpastes (whitening toothpaste (WTp), activated charcoal toothpaste (ACTp)). The specimens' Ra values were measured before and after 10,000 cycles of toothbrushing. The color parameters were measured and the color differences (ΔE00) were calculated. Data were statistically analyzed by two-way analysis of variance (ANOVA) and Tukey's HSD tests. A significant increase in the Ra values was observed after toothbrushing, except for the LaPM_Dw, ChDM_Dw, and all the CadPM specimens (p < 0.05). Toothbrushing with toothpastes increased the ΔE00 values of all ChPM and ChDM interim materials (p < 0.05). Before and after all toothbrushing procedures, the CadPM specimens had smoother and ChPM specimens had rougher surfaces than the other interim materials. The two tested toothpastes had similar effects on the Ra of all interim materials. Non-perceivable color changes were seen only with the CadPM_Dw group.

Effect of simulated tootbrushing on surface roughness of sealant agent coupled nanohybrid composite resins.

OBJECTIVE: To investigate the effect of toothbrushing on the surface roughness (Ra ) of different sealant agent coupled nanohybrid composite resins. MATERIALS AND METHODS: One hundred sixty disc-shaped (10 × 2 mm) specimens were prepared from four different nanohybrid composite resins (Z-550, Tetric EvoCeram, Clearfill Majesty, Ice). Specimen groups were divided into four subgroups for conventional polishing (control) and to apply three different surface sealant agents (Palaseal, Optiglaze, Biscover LV) (n = 10). The Ra values of the specimens were recorded before (Ra 0) and after 10,000 cycles of toothbrushing (Ra 1). The surface properties of the specimens were evaluated with scanning electron microscope (SEM). Data were statistically analyzed by two-way analysis of variance (ANOVA), Tukey HSD, and paired sample t tests. RESULTS: Composite resin material, surface treatment, and their interaction were significant on Ra values (p < 0.001). Significant decrease in Ra 0 values observed for surface sealant agent coupled Clearfill Majesty and Tetric EvoCeram composite resin groups compared with the control groups (p < 0.05). After simulated one-year toothbrushing, the control group of Clearfill Majesty had the highest Ra 1 value (p < 0.001). The Ra 1 values of all groups were significantly higher than the Ra 0 values (p < 0.05). CONCLUSIONS: Simulated 1-year toothbrushing increased the surface roughness of all nanohybrid composite resin materials. Optiglaze and Biscover LV sealant agents on Tetric EvoCeram, and all tested sealant agents on Clearfill Majesty enabled smoother surfaces than conventional polishing after toothbrushing. CLINICAL SIGNIFICANCE: Because toothbrushing increases the surface roughness of tested nanohybrid composite resins, the application of surface sealant agents on some of the tested resins can be considered for smoother surfaces.

Influence of chairside surface treatments on the shear bond strength of PEKK polymer to veneering resin materials: An in vitro study.

STATEMENT OF PROBLEM: High-performance thermoplastics have been adopted as an alternative restorative material to metal or ceramics. However, a straightforward surface modification process to provide a durable bond strength between the polymer and the veneering material is lacking. PURPOSE: The purpose of this in vitro study was to evaluate the shear bond strength (SBS) of different veneering resin materials to polyetherketoneketone (PEKK) after different surface treatments. MATERIAL AND METHODS: Rectangular (7×7×2 mm) PEKK specimens (N=120) were randomly allocated to the following 6 groups (n=20): untreated (Cnt); nonthermal plasma (NTP) treated; tribochemical silica airborne-particle abrasion with 30-µm silica-modified Al2O3 (Tbc); abraded with a coarse-grit diamond rotary instrument (Ab); tribochemical silica airborne-particle abrasion + plasma treated (Tbc_NTP); abraded + plasma treated (Ab_NTP). After a bonding agent (PEKK Bond) was applied to the specimens, each group was divided into 2 subgroups according to the applied veneering resin materials: polymethylmethacrylate (PMMA) and nanohybrid composite resin (NHC, n=10). The specimens were stored in water for 24 hours at 37 °C and subjected to the SBS test by using a universal testing machine, and failure modes were evaluated using a stereomicroscope. Two-way analysis of variance (ANOVA) was performed followed by the Tukey honestly significant difference (HSD) test to statistically analyze the data (α=.05). RESULTS: The 2-way ANOVA showed that surface treatment methods, veneering material, and their interactions were significantly different on the SBS values (P<.001). The highest SBS values were determined for the Tbc and Tbc_NTP treatment groups not only for PMMA (10.71 to 11.63 MPa) but also for NHC (19.80 to 20.60 MPa) veneering resin materials (P<.05). CONCLUSIONS: The bonding capacity of PEKK to the PMMA and NHC veneering resin materials can be significantly improved by using tribochemical silica airborne-particle abrasion alone or with nonthermal plasma surface treatment techniques. Furthermore, using NHC veneering resin material is recommended over PMMA.

Effects of denture cleaning solutions on the retention of Hader bar clips.

STATEMENT OF PROBLEM: The clinical performance of implant-retained overdentures (IODs) with plastic bar clips made of different materials in the same design and dimensions may vary according to the patient's daily home care procedures. However, information about the effects of denture cleaning solutions on the retention of Hader bar clips is lacking. PURPOSE: The purpose of this in vitro study was to evaluate the retention of Hader bar clips made of different polymers after being soaked in denture cleaning solutions. MATERIAL AND METHODS: Ninety Hader bar clips made of polyamide (PA, n=30), polytetrafluoroethylene (PTFE, n=30), and polyetherketoneketone (PEKK, n=30) materials were tested. Two multiunit abutments were screwed onto the implant analogs and embedded into an acrylic resin block in a standardized position. The digital scanning of the abutments was acquired, and the bar patrix of each material system milled from a cobalt-chromium (Co-Cr) alloy disk by using computer-aided design and computer-aided manufacturing (CAD-CAM). After the milled bar patrices were screwed onto abutments and the metal housings of the bar clips were embedded into acrylic resin blocks, they were connected passively at the same angulation to a universal testing machine. The initial retention values of all Hader bar clips were measured, and each material system was divided into 3 subgroups (n=10) before soaking in the cleaning solutions: distilled water (DW), 5% sodium hypochlorite (NaOCl), or sodium bicarbonate-sodium perborate (SBSP). Each material was soaked for the equivalent of 3 months of clinical use. The final retention values of each Hader bar clip were measured. The data were statistically analyzed by using a 2-way analysis of variance (ANOVA), the Tukey honestly significant difference (HSD) test, and the paired sample t test (α=.05). RESULTS: The 2-way ANOVA showed that the denture cleaning solution, the clip material, and their interactions led to significantly different retention values (P<.001). A decrease was observed for the retention values of all test groups after soaking in the cleaning solutions (P<.05). No retention was observed for the PTFE clips after soaking in the 5% NaOCI solution. CONCLUSIONS: The denture cleaning solutions negatively affected the retention of Hader bar clips, regardless of the type of solution and clip material. The 5% NaOCI solution not only decreased the retention of PTFE clips but also completely degraded it. It is recommended that 5% NaOCI solution be avoided for the daily care of IODs with PTFE clips.

Effect of surface treatments on the bond strength of indirect resin composite to resin matrix ceramics.

PURPOSE: The purpose of this study was to evaluate the shear bond strength (SBS) of an indirect resin composite (IRC) to the various resin matrix ceramic (RMC) blocks using different surface treatments. MATERIALS AND METHODS: Ninety-nine cubic RMC specimens consisting of a resin nanoceramic (RNC), a polymer-infiltrated hybrid ceramic (PIHC), and a flexible hybrid ceramic (FHC) were divided randomly into three surface treatment subgroups (n = 11). In the experimental groups, untreated (Cnt), tribochemical silica coating (Tbc), and Neodymium-Doped Yttrium Aluminum Garnet (Nd:YAG) laser irradiation (Lsr) with 3 W (150 mJ/pulse, 20 Hz for 20 sec.) were used as surface treatments. An indirect composite resin (IRC) was layered with a disc-shape mold (2 × 3 mm) onto the treated-ceramic surfaces and the specimens submitted to thermal cycling (6000 cycles, 5 - 55℃). The SBS test of specimens was performed using a universal testing machine and the specimens were examined with a scanning electron microscope to determine the failure mode. Data were statistically analyzed with two-way analysis of variance (ANOVA) and Tukey HSD test (α=.05). RESULTS: According to the two-way ANOVA, only the surface treatment parameter was statistically significant (P<.05) on the SBS of IRC to RMC. The SBS values of Lsr-applied RMC groups were significantly higher than Cnt groups for each RMC material, (P<.05). Significant differences were also determined between Tbc surface treatment applied and untreated (Cnt) PIHC materials (P=.039). CONCLUSION: For promoting a reliable bond strength during characterization of RMC with IRC, Nd:YAG laser or Tbc surface treatment technique should be used, putting in consideration the microstructure and composition of RMC materials and appropriate parameters for each material.

Does Sterilization Affect the Push Out Bond Strength of Experimental Dentin Posts? / ¿Afecta la esterilización la fuerza de adherencia de los postes de dentina experimentales?

ABSTRACT The purpose of this preliminary study is to evaluate the push-out bond strength (PBS) of experimental dentin posts (EDPs) obtained from human and bovine teeth sterilized by autoclaving and gamma radiation. Eighty-four mandibulary premolars were obturated and divided into three post groups: the glass fiber group (Fb) human EDP group (Hm) and the bovine EDP group (Bv). Three subgroups (n=12) were obtained for each EDP groups according to the sterilization methods; no sterilization (Cnt), steam autoclaving (Aut), and gamma radiation (Rad) a total dose of 25 kGy. All posts were cemented to root canals using a dual cured resin cement (Panavia SA). After the micro slices (1mm in thickness) were obtained of each subgroup, PBS test was performed. Data were analyzed using two-way ANOVA and Tukey's multiple comparison tests (α=.05). The post type and sterilization method was significantly effective on the PBS values according to the ANOVA (P<.001). No sterilization apllied EDP groups showed significantly higher PBS values than the sterilized groups (P<.001). Bv_Cnt (9.42 ±1.31) showed significantly lower PBS values than both Fb (12.36 ±1.54) and Hm_Cnt (11.06 ±1.38) groups (P<.001). Both steam autoclaving and gamma radiation affect the PBS values and fracture modes of EDPs negatively. The bovine EDPs are not as effective as human EDPs with regard to the PBS to the root dentin.

RESUMEN El propósito de este estudio preliminar es evaluar el push-out bond strength de los postes de dentina experimentales (PDE) obtenidos de dientes humanos y bovinos esterilizados por autoclave y radiación gamma. Ochenta y cuatro premolares mandibulares fueron obturadores y se dividieron en tres grupos experimentales de postes: el grupo de fibra de vidrio (Fb) grupo PDE humano (Hm) y el grupo PDE bovino (Bv). Se obtuvieron tres subgrupos (n=12) para cada grupo de PDE según los métodos de esterilización; sin esterilización (Cnt), autoclave a vapor (Aut) y radiación gamma (Rad) con una dosis total de 25 kGy. Todos los postes se cementaron a los conductos radiculares utilizando un cemento de resina de curado doble (Panavia SA). Después de que se obtuvieron las micro rebanadas (1 mm de espesor) de cada subgrupo, se realizó una prueba de push-out bond strength. Los datos se analizaron utilizando ANOVA de dos vías y las pruebas de comparación múltiple de Tukey (α=.05). El tipo de poste y el método de esterilización fueron significativamente efectivos en los valores de push-out bond strength según el ANOVA (P <.001). Los grupos de PDE no aplicados a la esterilización mostraron valores de push-out bond strength significativamente mayores que los grupos esterilizados (p <0,001). Bv_Cnt (9.42 ±1.31) mostró valores de push-out bond strength significativamente más bajos que los grupos Fb (12.36 ±1.54) y Hm_Cnt (11.06 ±1.38) (P <.001). Tanto el autoclave al vapor como la radiación gamma afectan negativamente los valores de push-out bond strength y los modos de fractura de los PDE. Los PDE bovinos no son tan efectivos como los PDE humanos con respecto a la fuerza de adhesión a la dentina de la raíz.

Resin cements effect on the final color of novel monolithic CAD/CAM restorations.

BACKGROUND: This study investigated the effect of resin cement shade on the final color of computer aided design/computer aided manufacture (CAD/CAM) restorations. METHODS: Thirty CAD/CAM block specimens were fabricated (14×12×1.5 mm) by cutting blocks (Vita Mark II [VM], Vita Enamic [VE], and Lava Ultimate [LU]). Forty cement specimens were prepared (14×12×0.2 mm) using resin cement (RelyX Ultimate Tr, A1, A3O, Bl). Color measurements of CAD/CAM specimens were made without (control) and with each /shade of resin cement (test) with a spectrophotometer. Color differences (ΔE00) between the control and test groups were calculated and analyzed by 2-way ANOVA and subsequent pairwise testing. Comparisons were performed by using Tukey's multiple comparison tests (α=0.05). RESULTS: Both cement shade and interaction between cement shade CAD/CAM block type parameters were significant on color differences (P<0.05). A3O cement resulted in a clinically unacceptable color differences (ΔE00>2.25) for each tested CAD/CAM blocks. ΔE00 values of VM_A1 and VE_A1 groups were also higher than clinically unacceptable level (ΔE00>2.25). ΔE00 value of VE_Tr was lower than visually perceptible level (∆E00≤1.30). There was no statistically significant difference found between the ∆E00 values of CAD/CAM blocks in the same shade of cement groups (P>0.05). CONCLUSIONS: Tested CAD/CAM blocks were similarly affected by the cement shade and thus may have similar optical features.

Shear Bond Strength of Nanohybrid Composite to the Resin Matrix Ceramics After Different Surface Treatments.

OBJECTIVE: The purpose of this study was to evaluate the effects of different surface treatments on the shear bond strength (SBS) of a composite resin to the various resin matrix ceramics (RMC). BACKGROUND: Clinical applications of physical and chemical surface conditioning methods may be required for RMC to optimize the adhesion of additional resin materials. MATERIALS AND METHODS: Ninety-nine RMC specimens (6 × 6 × 2 mm) were prepared from a resin nanoceramic (RNC), a polymer-infiltrated hybrid ceramic (PIHC), and a flexible hybrid ceramic (FHC) block with a cutting machine under copious water. All specimens divided randomly into three surface treatment subgroups (n = 11): (1) untreated (Cnt), (2) tribochemical silica coated (Tbc), and (3) neodymium-doped yttrium aluminum garnet (Nd:YAG) laser irradiated with 3 W (150 mJ/pulse, 20 Hz) for 20 sec. A nanohybrid composite resin was layered with a disc-shape mold (2 × 3 mm) onto the ceramics and submitted to thermal cycling (3000 cycles, 5-55°C). The SBS test of specimens was performed using a universal testing machine. Data were statistically analyzed with two-way analysis of variance (ANOVA) and Tukey HSD test (α = 0.05). RESULTS: The type of RMC, surface treatments, and their interactions was statistically significant on SBS, according to the ANOVA (p < 0.05). Both the Tbc and Lsr surface treatments significantly increased the SBS values of FHC (p < 0.001), while significant increases were observed only for Lsr0applied RNC and Tbc applied PIHC groups (p < 0.001). CONCLUSIONS: The tribochemical silica coating and laser irradiation techniques may be suitable for improving the surface topography of specific types of RMC. While the same surface treatment technique may not provide similar successful results for all types of RMC, it is recommended to choose the most effective and reliable technique for clinical application.

Multidisciplinary approach to a subgingivally fractured incisor tooth: A case report.

This case report describes a multidisciplinary approach using orthodontic forced eruption to facilitate prosthetic restoration of a subgingivally fractured maxillary permanent central incisor. A 14-year-old male patient presented at the pediatric dental clinic due to unesthetic appareance and for management of a fractured maxillary right central incisor tooth. Intraoral examination revealed that the maxillary right central incisor had sustained a crown-root fracture with pulp exposure. We treated the tooth endodontically and performed orthodontic root extrusion with a modified Hawley appliance prior to prosthetic rehabilitation. Approximately 2-3 mm of extrusion of the tooth was obtained within 8 weeks. A fiber post was then inserted into the root canal, and final restoration was completed with an all-ceramic crown. Follow-up 18 months after treatment revealed good periodontal health, esthetics and normal function.

Influence of the color of composite resin foundation and luting cement on the final color of lithium disilicate ceramic systems.

STATEMENT OF PROBLEM: Lithium disilicate restorations are commonly used, particularly in the anterior region. The color of the underlying composite resin foundation (CRF) and luting cement may negatively affect the color of lithium disilicate ceramic restorations. PURPOSE: The purpose of this in vitro study was to investigate the effect of CRF and resin cement materials on the color of lithium disilicate ceramics in 2 different translucencies. MATERIAL AND METHODS: Twenty disks (11×1.5 mm, shade A2) were fabricated from medium-opacity (mo) (n=10) and high-translucency (ht) (n=10) lithium disilicate (Lds) blocks (IPS e.max Press). Five CRF disks (11×3 mm) were fabricated in 5 different shades (A1, A2, A3, B2, C2) and 30 resin cement disks (11×0.2 mm) in the shades of translucent (Tr), universal (Un=A2), and white-opaque (Wo). Ceramic specimens were placed on each CRF, and the resin cement combination and color was measured with a spectrophotometer. CIELAB color coordinates were recorded, and the color coordinates of both ceramics on the shades of the A2 CRF and resin cement were saved as the control. Color differences (ΔE00) between the control and test groups were calculated. Data were analyzed with 3-way analysis ANOVA and compared with the Tukey HSD test (α=.05). RESULTS: The ΔE00 values were influenced by the shades of the CRF, resin cement materials, and also their interactions (P<.05). The ΔE00 values were not affected by the ceramic type. The ΔE00 values of the Wo cement groups (1.73 to 2.96) were significantly higher than those of the other cement shades (0.88 to 1.29) for each ceramic type and CRF shade (P<.05). CONCLUSIONS: Lithium disilicate ceramics in 2 different translucencies were similarly influenced by the color of the underlying cement and CRF. When translucent and universal cement shades were used, the core shade did not affect the final color of the ceramics. White opaque cement caused clinically unacceptable color changes in both ceramics on all shades of CRFs except the C2 CRF and when high translucency ceramic was used on the A2 CRF. These changes were clinically acceptable, but perceptible.

Effect of brand and shade of resin cements on the final color of lithium disilicate ceramic.

STATEMENT OF PROBLEM: Resin cements are available in various shades from different manufacturers. However, there is no standard for the optical properties of these cements, which may result in differences in the color of translucent ceramic restorations. PURPOSE: The purpose of this in vitro study was to evaluate the effects of different shades and brands of resin cements on the color of a lithium disilicate ceramic. MATERIALS AND METHODS: Ten ceramic disks (11×1.5 mm, shade A2) were fabricated from lithium disilicate high-translucency blocks. Eighty cement disks (11×0.2 mm) were fabricated from 4 brands (Maxcem; Variolink; Clearfil; and RelyX) of resin cements in translucent and universal (shade A2) shades. Color measurements of ceramic specimens were made without (control) and with each brand/shade of resin cement material (test) with a spectrophotometer, and International Commission on Illumination Lab (CIELab) color coordinates were recorded. Color differences (ΔE00) between the control and test groups were calculated. ΔE00 results were analyzed by 2-way ANOVA and subsequent pairwise testing. Comparisons were performed using the Student t test, and then all P values were corrected with the step-down Bonferroni procedure (α=.05). RESULTS: The effect on the ΔE00 values (P<.001) of the brand and shade of resin cement materials was significant. Both shades of RelyX cement groups had significantly lower and Variolink_translucent cement group had significantly higher ΔE00 results than other brands (P<.05). Only RelyX_translucent and RelyX_universal were significantly different from each other for comparisons within brands (P<.05). The effect of RelyX_universal cement on the ceramic was not visually perceptible (ΔE00≤1.30). Clinically unacceptable results (ΔE00>2.25) were observed only for Variolink_translucent cement (2.36). CONCLUSIONS: Same-shade resin cements from different manufacturers had different effects on the color of lithium disilicate ceramic. The effects of different shades of resin cements from the same manufacturer on the color of lithium disilicate ceramic were statistically different for only RelyX, which may also be considered clinically different based on clinical acceptability thresholds for color difference values (ΔE00). Accordingly, this effect may be considered clinically different for Variolink but not clinically different for Maxcem and Clearfil.

Efficacy of denture cleaners on the surface roughness and Candida albicans adherence of sealant agent coupled denture base materials.

This study investigated the effect of denture cleansers on the surface roughness and Candida albicans adherence of surface sealant agent coupled denture base resins. One hundred and twenty specimens were fabricated from 2 polymethyl methacrylate (PMMA) (Meliodent; Acron MC) and 1 polyamide (Deflex) denture base materials, coated with a sealant agent (Palaseal) and divided into 4 groups (n=10) according to overnight cleaning procedures: distilled water (control), 5% sodium hypochlorite (NaOCl) and two different sodium perborate (Corega; Rapident). The surface roughness values were measured with a profilometer before (Ra0) and after 90 days immersion in denture cleaners (Ra1). Specimens were incubated with Candida albicans suspension and Candida colony- forming units (CFU) (Cfu/mm) were counted. Significant differences were found, between the Ra0 and Ra1 values of 5% NaOCl applied Acron MC, Deflex and also Rapident applied Deflex groups (p<0.05). Denture cleaning procedures had no significant effects on the quantitiy of Candida albicans.

Influence of implant abutment material on the color of different ceramic crown systems.

STATEMENT OF PROBLEM: Ceramics are widely used for anterior restorations; however, clinical color reproduction still constitutes a challenge particularly when the ceramic crowns are used on titanium implant abutments. PURPOSE: The purpose of this in vitro study was to investigate the effect of implant abutment material on the color of different ceramic material systems. MATERIAL AND METHODS: Forty disks (11×1.5 mm, shade A2) were fabricated from medium-opacity (mo) and high-translucency (ht) lithium disilicate (IPS e.max) blocks, an aluminous ceramic (VITA In-Ceram Alumina), and a zirconia (Zirkonzahn) ceramic system. Disks were fabricated to represent 3 different implant abutments (zirconia, gold-palladium, and titanium) and dentin (composite resin, A2 shade) as background (11×2 mm). Disk-shaped composite resin specimens in A2 shade were fabricated to represent the cement layer. The color measurements of ceramic specimens were made on composite resin abutment materials using a spectrophotometer. CIELab color coordinates were recorded, and the color coordinates measured on composite resin background served as the control group. Color differences (ΔE00) between the control and test groups were calculated. The data were analyzed with 2-way analysis of variance (ANOVA) and compared with the Tukey HSD test (α=.05). RESULTS: The ceramics system, abutment material, and their interaction were significant for ΔE00 values (P<.001). Clinically unacceptable results (ΔE00>2.25) were observed for lithium disilicate ceramics on titanium abutments (2.46-2.50). The ΔE00 values of lithium disilicate ceramics for gold-palladium and titanium abutments were significantly higher than for other groups (P<.05). CONCLUSION: The color results (ΔE00>2.25) of an implant-supported lithium disilicate ceramic restoration may be clinically unacceptable if it is fabricated over a titanium abutment. Zirconia may be a more suitable abutment material for implant-supported ceramic restorations.

Effect of surface sealant agents on the surface roughness and color stability of denture base materials.

STATEMENT OF PROBLEM: The effects of surface sealant agents on the surface roughness and color stability of denture base materials are unknown. PURPOSE: The purpose of this in vitro study was to evaluate the effects of different polishing methods on the surface roughness and color stability of denture base materials. MATERIAL AND METHODS: A total of 120 specimens were fabricated from 2 poly(methyl methacrylate) (PMMA) and 1 polyamide denture base materials and divided into 4 groups (n=10 in each group) according to the applied surface treatment procedure: conventional polishing (control) and 3 surface sealant coupling methods. Surface roughness average (Ra) values were measured using a profilometer. Color parameters were measured using a spectrophotometer before and after being stained with coffee. Color differences (CIEDE 2000 [ΔE00]) were calculated. Data were statistically analyzed using 2-way ANOVA and Tukey honest significant difference test (α=.05). RESULTS: No statistically significant difference were found between surface roughness values of the control and those of the specimens treated using a surface sealant agent (P>.05). The highest color difference was calculated for the polyamide control group. Statistically significant differences were found between the control group and the group treated with the polyamide surface sealant agent (P<.05). CONCLUSIONS: All specimens had a surface roughness value higher than the plaque accumulation threshold (0.20 µm). The color changes observed were clinically unacceptable, except for conventionally polished and one type of surface sealant applied microwave polymerized PMMA denture base material.