Fabrication of lithium silicate ceramic veneers with a CAD/CAM approach: A clinical report of cleidocranial dysplasia

Flexural Strength Properties of Five Different Monolithic Computer-Aided Design/Computer-Aided Manufacturing Ceramic Materials: An In Vitro Study

Objective

The purpose of this in vitro study is to compare the flexural strength and Weibull modulus of 5 different monolithic computer-aided design/computer-aided manufacturing (CAD/CAM) ceramics.

Methods

A total of 50 specimens were fabricated, 10 from each of the following materials: lithium disilicate-based ceramic (IPS e.max CAD), zirconia -reinforced lithium-silicate ceramic (Vita Suprinity), leucite-based glass ceramic (IPS Empress CAD), and two zirconia-based ceramics (Zenostar and CopraSmile). The specimens were 4 mm wide, 2 mm thick, and 16 mm long. Flexural strength test was executed using a universal testing machine (Model 5980, Instron Industrial Products, Norwood, MA, USA). The two-parameter Weibull distribution function was used to analyze the variability of flexural strength values. Statistical analysis was performed on SPSS Version 23 (IBM Corp., Armonk, NY, USA) using one-way analysis of variance (ANOVA) and post-hoc Tukey’s test.

Results

Suprinity had the highest Weibull modulus value, while Empress CAD displayed the lowest value. One-way ANOVA showed significant difference in the flexural strength between the different materials tested (p<0.05). Post-hoc analysis revealed significant differences among all the test groups in terms of flexural strength. Zenostar presented the highest mean flexural strength value (1033.90 MPa), while Empress CAD had the lowest value.

Conclusion

High-translucency zirconia had superior flexural properties than translucent zirconia, lithium disilicate ceramics, zirconia-reinforced lithium silicate ceramics, and leucite-based glass ceramics.

Mechanical response of different frameworks for maxillary all-on-four implant-supported fixed dental prosthesis: 3D finite element analysis

This study's purpose is to assess the stress distribution in the peri-implant bone, implants, and prosthetic framework using two different posterior implant angles. All-on-four maxillary prostheses fabricated from feldspathic-ceramic-veneered zirconia-reinforced lithium silicate (ZLS) and feldspathic-ceramic-veneered cobalt-chromium (CoCr) were designed with 17 or 30-degree-angled posterior implants. Posterior cantilever and frontal vertical loads were applied to all models. The distribution of maximum and minimum principal stresses (σmax and σmin) and von Mises stress (σVM) was evaluated. Under posterior cantilever load, with an increase in posterior implant angle, σmax decreased by 4 and 7 MPa in the cortical bone when ZLS and CoCr were used as a prosthetic framework, respectively. Regardless of the framework material, 17-degree-angled posterior implants showed the highest σVM (541.36 MPa under posterior cantilever load; 110.79 MPa under frontal vertical load) values. Regardless of the posterior implant angle, ZLS framework showed the highest σVM (91.59 MPa under posterior cantilever load; 218.99 MPa under frontal vertical load) values. Increasing implant angle from 17 to 30° caused a decrease in σmax values in the cortical bone. Designs with 30-degree posterior implant angles and ZLS framework material may be preferred in All-on-four implant-supported fixed complete dentures.

Comparison of CAD/CAM manufactured implant-supported crowns with different analyses

Background

Present study compared the failure load of CAD/CAM-manufactured implant-supported crowns and the stress distribution on the prosthesis-implant-bone complex with different restoration techniques.

Methods

The materials were divided into four groups: group L-M: lithium disilicate ceramic (LDS, monolithic), group L-V: LDS ceramic (veneering), group ZL-M: zirconia-reinforced lithium silicate ceramic (ZLS, monolithic), group ZL-V: ZLS ceramic (veneering). Crown restorations were subjected to load-to-failure test (0.5 mm/min). Failure loads of each group were statistically analyzed (two-way ANOVA, post hoc Tukey HSD, α = 0.05). Finite element analysis (FEA) was used to compare the stress distribution of crown restorations.

Results

Group L-M had the highest failure load (2891.88 ± 410.12 N) with a significant difference from other groups (p < 0.05). Although there was a significant difference between group ZL-M (1750.28 ± 314.96 N) and ZL-V (2202.55 ± 503.14 N), there was no significant difference from group L-V in both groups (2077.37 ± 356.59 N) (p > 0.05).

Conclusions

The veneer application had opposite effects on ceramics, increased the failure load of ZLS and reduced it for LDS without a statistically significant difference. Both materials are suitable for implant-supported crowns. Different restorative materials did not influence the stress distribution, but monolithic restorations reduced the stress concentration on the implant and bone.

Evaluation of marginal adaptation of Co-Cr-Mo metal crowns fabricated by traditional method and computer-aided technologies

Background/purpose

The purpose of this study was to evaluate the marginal gaps of dental restorations manufactured using conventional loss wax and casting, computer-aided design/computer-aided manufacturing (CAD/CAM), and 3D printing methods.

Materials and methods

A zirconia master die model with an upper right first molar resin crown was prepared as a standardized model. A total of 30 resin master die models were duplicated from this standard model. Simultaneously, 10 Co—Cr—Mo metal crowns were individually obtained using the conventional loss wax and casting method (Group A), selective laser sintering (Group B), and CAD/CAM (Group C), respectively. The marginal gaps between the crowns fabricated conventional and digital methods with master die models were calculated using a 3D replica and mapping technique.

Results

Statistical analyses revealed there were significant differences in the marginal gaps in the group A with group B and C (p < 0.05). The mean marginal gaps between dental crowns with die models were 76 ± 61 μm, 116 ± 92 μm, and 121 ± 98 μm for groups A, B, and C, respectively.

Conclusion

Within the limitations of this study, the marginal gaps were clinical acceptable in conventional and digital techniques.

A Step-by-Step Conservative Approach for CAD-CAM Laminate Veneers

The use of CAD/CAM technology has allowed the fabrication of ceramic restorations efficiently and with predictable results. Lithium disilicate is a type of glass ceramic material that can be used for the elaboration of laminate veneers, being monolithic restorations which require characterization through a covering ceramic in order to achieve acceptable esthetic results. The next case report shows a predictable clinical protocol for the rehabilitation of the anterior teeth through the preparation of CAD/CAM veneers (e.max CAD, Ivoclar Vivadent, Liechtenstein) which have been characterized by a nanofluorapatite ceramic (e.max Ceram, Ivoclar Vivadent, Liechtenstein) through the layering technique.