Immediate definitive individualized abutments reduce peri-implant bone loss: a randomized controlled split-mouth study on 16 patients

WOS: 000419148200048PubMed ID: 28567530This paper aims to observe peri-implant time-related vertical bone level and soft tissue changes with immediate, non-detached glass-ceramic (lithium-disilicate) individualized abutments and dis-/reconnections. Sixteen split-mouth patients received provisionalized immediate definitive individualized abutments (test T) versus dis-/reconnected individualized abutments (control C). In group T, digital impressions were made by using titanium bases (Conelog, Camlog), and individualized abutments (E.maxCAD) and temporary crowns (TelioCAD) were designed and milled (CerecMCXL). Lithium-disilicate abutments were crystallized and luted (Multilink Hybrid Abutment) to titanium bases. Non-occluding temporary crowns were connected to abutments. After 16 weeks, definitive digital restorations were delivered. In group C, 8 weeks were allowed after healing cap mounting for conventional impressions. Lithium-disilicate individualized abutments were produced, try-ins were performed by dis-/reconnections. Crowns were luted. Cone beam computed tomography (CBCT) images were obtained at restoration delivery, 12 months and 24 months. Pink esthetic scoring was made, plaque-gingival index measurements were done and statistical analyses (Shapiro-Wilk, Mann-Whitney U, Wilcoxon's, Spearman's rank, alpha = 0.05) were completed. No implant failures occurred. At 12 months, T (-0.1 +/- 0.14 mm) exhibited significantly reduced vertical bone loss only on the labial side than C (-0.24 +/- 0.13 mm) (p < 0.05). In T, all sides except distal presented reduced vertical bone loss at 24 months (p < 0.05). Vertical bone loss for all measurement sides in both C (-0.12 +/- 0.09 mm; -0.18 +/- 0.11 mm) and T (-0.17 +/- 0.11; -0.26 +/- 0.10 mm) was higher for 24 months than 12 months, respectively (p < 0.05). Reduced vertical bone loss was observed around implants with immediate definitive individualized abutments than abutments with repeated dis-/reconnections. Non-detached immediate definitive lithium-disilicate individualized abutments and provisionalization through digital technology resulted in successful clinical outcomes and can be routinely applied.Camlog Foundation [CF41104]This study was funded by the Camlog Foundation (Funding no: CF41104)

Colour stability of sectional laminate veneers: A laboratory study

Elter, Bahar/0000-0002-8971-6819WOS:000637599100001PubMed: 33721347Background This study aimed to evaluate the colour stability of sectional laminate veneers (SLVs) fabricated with four and cemented with two different materials. Methods Eighty SLVs were prepared with a thickness of 0.2-0.4 mm from IPS e.max CAD, Lava Ultimate, CEREC Blocs and IPS InLine and were cemented with Variolink Veneer and Variolink N to form eight groups (n:10). After cementation, specimens underwent 5000 thermocyles prior to immersion in a coffee solution. Results Colour change before and after thermal cycling did not reveal significant differences (P > 0.05). After coffee immersion, significant colour change was observed in all groups (P > 0.05). Only IPS InLine cemented with Variolink Veneer was considered clinically acceptable ( increment E 3.3) discolouration except for the IPS InLine cemented with light-curing resin cement. Cementation with either dual-curing or light-curing resin cements does not by itself affect colour stability. The highest marginal discolouration was in the Lava Ultimate group while no discolouration was detected in the IPS InLine group.Ege University Scientific Research Projects CoordinationEge University [2013 DIS-004]This study was supported by Ege University Scientific Research Projects Coordination with the project number 2013 DIS-004. The authors do not have any financial interest in the companies whose materials are included in this article

Effect of Veneering Methods on Zirconia Framework-Veneer Ceramic Adhesion and Fracture Resistance of Single Crowns

WOS: 000367471900004PubMed ID: 25319017Purpose: The aim of this study was to evaluate the fracture resistance (FR) and shear bond strength (SBS) via finite element analysis (FEA) of zirconia framework veneered with different methods. Materials and Methods: Zirconia frameworks were prepared as crowns for FR and cubic blocks for SBS (N = 60, n = 10). The specimens were veneered with one of the following veneering methods: (a) overcemented file-splitting (OCF), (b) layering (L), or (c) overpressing (P). For crowns, stainless steel dies (N = 30; chamfer: 1 mm) were scanned using a contrast spray. Bilayered design for OCF and reduced design (1 mm) for both L and P were performed by computer-aided design and manufacturing. For the SBS test, zirconia blocks were sectioned (4 x 4 x 4 mm(3)) under water cooling and sintered. Frameworks were veneered with compatible ceramics for each veneering method and subjected to mechanical tests. The milled suprastructures were bonded to zirconia frameworks using a resin composite in Group OCF and photopolymerized. Crowns were cemented to the metal dies with resin modified glass-ionomer cement. All specimens were stored at 37 degrees C, 100% humidity for 48 hours prior to mechanical tests. Data were statistically analyzed (ANOVA, Bonferroni tests, alpha = 0.05). Fractured specimens were examined under scanning electron microscopy (SEM), and FEA modeling of the crowns was performed. Results: Mean FR values (N) were significantly higher with L (6102 +/- 1519) and P (4117 +/- 1083) than with of OCF (1900 +/- 254) (p = 0.01). The mean SBS (MPa) in OCF (24 +/- 4) was significantly lower (p 0.05). For crown restorations, while only adhesive failures were found in OCF, cohesive failures within veneering ceramic were more frequent in P and L. FEA verified these findings. Conclusion: Veneering methods based on layering or pressing may reduce ceramic chipping but the overcemented file-splitting method does not seem to prevent this failure. Clinical Significance: Layering and overpressing veneering methods on zirconia frameworks with reduced design might decrease chipping compared to overcemented file-splitting, where in the latter, zirconia framework and feldspathic suprastructure are combined using a resin cement.Ege University Scientific Research Project DepartmentEge University [2011-DIS-006]This research was supported in part by the Ege University Scientific Research Project Department (Project no. 2011-DIS-006)

A Customized Zirconia Abutment Design Combined with a CAD/CAM Laminate Veneer: A Clinical Report

WOS: 000351884800006PubMed ID: 25738340An alternative prosthetic treatment approach for single implants in the maxillary esthetic zone with an improper implant axis, limited interocclusal distance, inadequate abutment retention, and screw holes located at the labial surface is presented in this clinical report. The gingiva and soft tissues were contoured with provisional composite restorations to mimic the emergence profile of lateral incisors. Prefabricated zirconia abutments were customized with laminate veneer preparations by appropriate ceramic build-up with reference from the reshaped gingiva to avoid labiolingual overcontour. The laminate veneers were fabricated by computer-aided design/computer-assisted manufacture to cover the screw hole of the angulated abutment at the labial surface. Preliminary results revealed improvement in esthetics; however, long-term clinical follow-up should be performed

Microshear Bond Strength and Finite Element Analysis of Resin Composite Adhesion to Press-on-Metal Ceramic for Repair Actions after Various Conditioning Methods

WOS: 000334323300010PubMed ID: 23878833Purpose: This study evaluated the repair bond strength of differently surface-conditioned press-on-metal ceramic to repair composites and determined the location of the accumulated stresses by finite element analysis. Materials and Methods: Press-on-metal ceramic disks (IPS InLine PoM, lvoclar Vivadent) (N = 45, diameter: 3 mm, height: 2 mm) were randomly divided into 3 groups (n = 15 per group) and conditioned with one of the following methods: 9.5% hydrofluoric acid (HF) (Porcelain etch), tribochemical silica coating (TS) (CoJet), and an unconditioned group acted as the control (C). Each group was divided into three subgroups depending on the repair composite resins: a) Arabesk Top (V, a microhybrid; VOCO), b) Filtek Z250 (F, a hybrid;3M ESPE); c) Tetric Evo-Ceram (T, a nanohybrid; lvoclar Vivadent) (n = 5 per subgroup). Repair composites disks (diameter: 1 mm, height: 1 mm) were photopolymerized on each ceramic block. Microshear bond strength (MSB) tests were performed (1 mm/min) and the obtained data were statistically analyzed using 2-way ANOVA and Tukey's post-hoc test (alpha = 0.05). Failure types were analyzed under SEM. Vickers indentation hardness, Young's modulus, and finite element analysis (FEA) were performed complementary to MSB tests to determine stress accumulation areas. Results: MSB results were significantly affected by the surface conditioning methods (p = 0.0001), whereas the repair composite types did not show a significant effect (p = 0.108). The interaction terms between the repair composite and surface conditioning method were also statistically significant (p = 0.0001). The lowest MSB values (MPa +/- SD) were obtained in the control group (V = 4 +/- 0.8; F = 3.9 +/- 0.7; T = 4.1 +/- 0.7) (p 0.05). The control group presented exclusively adhesive failures. Cohesive failures in composite followed by mixed failure types were more common in HF and TS conditioned groups. Elasticity modulus of the composites were 22.9, 12.09, and 10.41 GPa for F, T, and V, respectively. Vickers hardness of the composites were 223, 232, and 375 HV for V, T, and F, respectively. Von Mises stresses in the FEA analysis for the V and T composites spread over a large area due to the low elastic modulus of the composite, whereas the F composite material accumulated more stresses at the bonded interface. Conclusion: Press-on-metal ceramic could best be repaired using tribochemical silica coating followed by silanization, regardless of the repair composite type in combination with their corresponding adhesive resins, providing that no cohesive ceramic failure was observed

Effect of Various Veneering Techniques on Mechanical Strength of Computer-Controlled Zirconia Framework Designs

WOS: 000340560800003PubMed ID: 24417370Purpose: The objectives of this study were to evaluate the fracture resistance (FR), flexural strength (FS), and shear bond strength (SBS) of zirconia framework material veneered with different methods and to assess the stress distributions using finite element analysis (FEA). Materials and Methods: Zirconia frameworks fabricated in the forms of crowns for FR, bars for FS, and disks for SBS (N = 90, n = 10) were veneered with either (a) file splitting (CAD-on) (CD), (b) layering (L), or (c) overpressing (P) methods. For crown specimens, stainless steel dies (N = 30; 1 mm chamfer) were scanned using the labside contrast spray. A bilayered design was produced for CD, whereas a reduced design (1 mm) was used for L and P to support the veneer by computer-aided design and manufacturing. For bar (1.5 x 5 x 25 mm(3)) and disk (2.5 mm diameter, 2.5 mm height) specimens, zirconia blocks were sectioned under water cooling with a low-speed diamond saw and sintered. To prepare the suprastructures in the appropriate shapes for the three mechanical tests, nano-fluorapatite ceramic was layered and fired for L, fluorapatite-ceramic was pressed for P, and the milled lithium-disilicate ceramics were fused with zirconia by a thixotropic glass ceramic for CD and then sintered for crystallization of veneering ceramic. Crowns were then cemented to the metal dies. All specimens were stored at 37. C, 100% humidity for 48 hours. Mechanical tests were performed, and data were statistically analyzed (ANOVA, Tukey's, alpha = 0.05). Stereomicroscopy and scanning electron microscopy (SEM) were used to evaluate the failure modes and surface structure. FEA modeling of the crowns was obtained. Results: Mean FR values (N +/- SD) of CD (4408 +/- 608) and L (4323 +/- 462) were higher than P (2507 +/- 594) (p < 0.05). Mean FS values (MPa +/- SD) of CD (583 +/- 63) and P (566 +/- 54) were higher than L (428 +/- 41) (p < 0.05). Mean SBS values (MPa +/- SD) of CD (49 +/- 6) (p < 0.05) were higher than L (28 +/- 5) and P (30 +/- 8). For crown restorations, while cohesive failures within ceramic and zirconia were seen in CD, cohesive failures within ceramic were found in both L and P. Results were verified by FEA. Conclusion: The file splitting technique showed higher bonding values in all mechanical tests, whereas a layering technique increased the FR when an anatomical core design was employed. Clinical significance: File splitting (CAD-on) or layering veneering ceramic on zirconia with a reduced framework design may reduce ceramic chipping.Ege University, Scientific Research Project DepartmentEge University [2011-DIS-006]This research was supported in part by the Ege University, Scientific Research Project Department (Project no. 2011-DIS-006)

Influence of Cervical Finish Line Type on the Marginal Adaptation of Zirconia Ceramic Crowns

WOS: 000269906600013PubMed ID: 19830974The current study evaluated the effect of different cervical finish line designs on the marginal adaptation of a zirconia ceramic. Four different marginal finish lines (c: chamfer, mc: mini-chamfer, fe: feather-edge and s: rounded shoulder) were prepared on phantom incisors. Die models for each preparation group (N=28, n=7 per finish line design group) were made of epoxy resin. Y-TZP (ICE Zirkon) frameworks were manufactured by a copy-milling system (Zirconzahn) using prefabricated blanks and tried on the master models for initial adaptation of the framework; they were then sintered, followed by veneering (Zirconzahn). The finished crowns were cemented with a polycarboxylate cement (Poly F) under 300 g load and ultrasonically cleaned. The specimens were sliced and the marginal gap was measured, considering absolute marginal opening (AMO) and marginal opening (MO) for each coping under a stereomicroscope with image processing software (Lucia). The measurements were statistically analyzed using the Kruskal Wallis, Mann Whitney and Wilcoxon Signed Ranks tests at a significance level of alpha=0.01. Means of AMO measurement (mu m) for the feather-edge finish line (87 +/- 10) was significantly lower than that of the chanifer (144 +/- 14), shoulder (114 +/- 16) and mini-chamfer finish line types (114 +/- 11) (p<0.01). Means of MO measurements was the lowest for feather-edge finish line (68 9) (p<0.01) and then, in ascending order, shoulder (95 +/- 9), mini-chamfer (97 +/- 12) and chanifer (128 +/- 10). The cervical finish line type had an influence on the marginal adaptation of the tested zirconia ceramic. Although the feather-edge finish line resulted in lower AMO and MO values, with its proven mechanical disadvantage, it cannot be recommended in clinical applications of zirconia crowns. This type of finish line has acted solely as a control group to test the null hypothesis in the current study. For better marginal adaptation, both shoulder and mini-chamfer finish line types could be suggested for zirconia crowns