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The aim was to investigate the marginal fit, internal adaptation and compressive strength of SLA provisionals (SLA) in comparison to CAD-CAM and conventional (CONV) interim fixed partial dentures (FPDs). Thirty interim FPDs were fabricated using CAD-CAM technology (CAD-CAM blocks Ceramill TEMP, PMMA), conventional molding technique (CONV) (TrimPlus, PMMA) and Stereolithography (SLA) method (Form 2, Formlabs, PMMA) (n = 10). Internal adaptation (occlusal, coronal, middle and cervical) and marginal integrity (inner and outer edge) was assessed using micro-computerized tomography (Micro-CT). The failure and compressive strength was assessed by application of a static load at a crosshead speed of 1 mm/min until fracture. Data was analysed using ANOVA and multiple comparisons test. The maximum and minimum marginal mis-fit was for CONV (283.3± 98.6 nm) and CAD-CAM (68.2± 18.1 m) groups. CAD-CAM (68.2± 18.1 m) and SLA (84.7± 27.5 m) provisionals showed comparable marginal mis-fit (p > 0.05). The mean failure load was significantly higher (p < 0.05) in CAD-CAM (687.86± 46.72 N), compared to SLA (534.8± 46.1 N) and CONV (492.7± 61.8 N) samples. Compressive strength for CAD-CAM (2.44± 0.27 MPa) samples was significantly higher (p < 0.05) than SLA (1.80± 0.15 MPa) and CONV (1.65± 0.20 MPa) groups. Marginal fit and internal adaptation of SLA printed FPDs was comparable to CAD-CAM interims. Compressive strength of the SLA interims FPDs can withstand intra-oral loads.

Objective: The aim was to compare restorative marginal integrity of ceramic crowns luted with bioactive and resin cements using micro-computed tomography (micro-CT) microleakage evaluations and bond strength assessment. Methods: Thirty molar teeth were prepared by sectioning and polishing for dentin exposure for resin cement build-ups. Teeth were randomly divided among three groups of cements: (1) bioactive (ACTIVA); (2) glass ionomer cement (GIC; Ketac Cem); and (3) resin luting agent (Nexus 3). Bonding regime and build-ups (4 mm × 2 mm) were performed using the recommended protocol. For microleakage assessment, 30 premolar teeth were prepared for dentin-bonded crowns using lithium disilicate ceramic and the computer-aided design and computer-aided manufacturing technique. Crowns were cemented with standard load, cement amount, and duration using three cements (Group A: bioactive; Group B: GIC; Group C: resin) and photopolymerized. Cemented crowns were evaluated for volumetric infiltration using micro-CT (Skyscan, Bruker 1173- at 86 kV, 93 µA, 620 ms) after immersion in 50% solution of silver nitrate (AgNO3) (24 hours). Shear bond strength (SBS) was assessed by fracture of cement build-ups at a cross-head speed of 0.5 mm/min in a universal testing machine. Results: Mean SBS among bioactive (21.54 ± 3.834 MPa) specimens was significantly higher than that for GIC (14.08 ± 3.25 MPa) specimens ( p < 0.01), but they were comparable to resin samples ( p > 0.05) (24.73 ± 4.32 MPa). Microleakage was significantly lower in crowns luted with bioactive (0.381 ± 0.134) cement compared to GIC (1.057 ± 0.399 mm3) ( p < 0.01) and resin (0.734 ± 0.166 mm3) ( p = 0.014) cemented crowns. The type of luting agent had a significant influence on the microleakage of crowns and bond strength to dentin ( p < 0.05). Conclusion: Bioactive cement exhibited less microleakage and comparable SBS to resin luting agents in in vitro conditions.

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Objective: The aim of this study was to evaluate marginal fit of yttrium tetragonal zirconia polycrystals (Y-TZP)’ copings with different finish line designs fabricated with various digital scanners and milling systems. Methods: Three model plastic teeth were prepared with three finish line designs: Design-1, continuous chamfer; Design-2, chamfer with shallow depression; Design-3, chamfer with deep depression. The “master models” were replicated using elastomeric polyvinyl siloxane impression material and poured in type IV stone generating 90 dies, 30 dies for each design. Dies were scanned and copings were milled utilizing three digital scanners and computer-aided design/computer-aided manufacturing (CAD/CAM) systems: System-1, InEos Red Scan (Sirona Dental Systems, Germany), Vitablocks® Mark II (VITA, Germany) copings milled by Cerec® inLab (Sirona Dental Systems, Germany); System-2, Cerec® AC Connect with BlueCam (Sirona Dental Systems, Germany), Vitablocks® Mark II (VITA, Germany) copings milled by Cerec® inLab (Sirona Dental Systems, Germany); and System-3, NobleProcera™ Optical Scanner (NobleBiocare™), procera zirconia coping milled by a Noble Procera™ milling machine (NobleBiocare™). Copings were seated on their respective “master models” and secured with uniform force. Eight measurements per coping were performed at pre-established points, with a metallurgical microscope (Zeiss, Germany) connected to a high precision digital video-micrometer (Javelin JV6000, California, USA) at 200 × magnification. Results: The tested systems demonstrated marginal gaps ranging from 12.4 to 26.6 µm. Results for marginal fit of milled copings fabricated using three systems with different finish line designs differed significantly ( p < 0.05). Procera zirconia copings scanned and milled with NobleProcera™ exhibited significantly lower marginal gaps compared to other specimen groups. However, InEos Red Scan/Vitablocks® Mark II/Cerec® inLab showed maximum marginal gaps among the study specimens. Conclusions: CAD-CAM manufactured Y-TZP’ copings exhibited marginal gaps ranging from 12.49 to 26.6 µm. The CAD-CAM fabrication system was a significant factor influencing the marginal misfit of Y-TZP’ copings. Margin design exhibited system dependent influence on the marginal misfit. Marginal misfit observed for all systems were within clinically acceptable parameters.

Aim: The aim of the study was to investigate the shear bond strength (SBS) and compressive strength (CS) of Er Cr YSGG laser (ECL) treated, re-bonded lithium disilicate (LD) ceramic in comparison to standard conventional conditioning (hydrofluoric acid (HFA) and silane). Methods: One hundred LD ceramic disks were divided equally for SBS and CS testing. Eighty samples were conventionally surface treated and bonded to resin cement followed by de-bonding of the cement build-up. All de-bonded specimens were divided into four groups based on re-bonding surface treatments (HFA, primer, adhesive, and ECL). Resin cement build-ups were performed in 40 specimens for SBS testing (universal testing machine); however, the remaining 40 specimens were tested for CS. Ten specimens each were used as controls (surface treatment was performed once and no primary resin cement bonding) for SBS and CS assessment. Surface topography was assessed using a scanning electron microscope. Results: The maximum and minimum SBS values were shown by groups: control (33.42 ± 3.28 megapascals (MPa)); and ECL (17.50 ± 2.22 MPa) respectively. The maximum and minimum CSs were displayed by specimens in the ECL group (439.45 ± 70.68 MPa) and the control group (237.28 ± 19.96 MPa), respectively. For ECL specimens, SBS was significantly lower and CS was significantly higher as compared to control specimens. Conclusions: Application of the Er Cr YSGG laser significantly improved the CS of de-bonded ceramic specimens. However, it did not show a positive influence on the bond integrity of re-bonded ceramics in comparison to conventional surface treatment regimes.

The aim was to assess the acceptable thickness of monolithic Lithium Disilicate (LD) ceramic in masking of Titanium (Ti) implant abutment by comparison to Zirconium (Zr) crowns through color matching. Forty LD and 10 Zr copings (control) using Hot-pressing and CAD-CAM techniques were fabricated. A standard Ti abutment (Straumann, ITI, Basel, Switzerland) was used as foundation substrate. LD crowns were divided into different thickness [1.0 mm (n = 10), 1.2 mm (n = 10), 1.5 mm (n = 10) and 1.8 mm (n = 10)] and 10 Zr copings (control) had 0.5 mm thickness. Different crown materials and crown thicknesses resulted in 5 study groups designated as Zr-Ti-0.5, LD-Ti1.0, LD-Ti-1.2, LD-Ti-1.5 and LD-Ti-1.8. Specimens were cemented to Ti abutments and using a spectrophotometer the difference of color for specimen and controls was determined by comparing ΔL, Δa and Δb (CIELab color system) and an overall ΔE. These were statistically compared using analysis of variance and Tukey post hoc multiple comparisons. Among LD specimens with Ti abutments, lowest color difference was achieved for LD-Ti-1.8 (2.3 ± 0.31) and the highest color difference was for LD-Ti-1.0 (4.93 ± 0.45). The lowest ΔE was recorded for Zr copings (control), which was lower than (p < 0 01) LD crowns of 1.0 and 1.2 mm thickness. LD crown thickness had a significant effect on ΔE (color difference) on Ti abutments. Masking of Ti abutments by 1.5 mm LD crowns was comparable to Zr specimens (control). Lithium disilicate crown of 1.5 mm thickness showed statistically comparable color stability to 0.5 mm Zr copings on Ti implant abutments.

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