Can lithium disilicate ceramic crowns be fabricated on the basis of CBCT data?

OBJECTIVES: Evaluating the fit of CAD/CAM lithium disilicate ceramic crowns fabricated on basis of direct and indirect digitalization of impressions by CBCT or of dental casts. MATERIAL AND METHODS: A metal model with a molar chamfer preparation was digitized (n = 12 per group) in four ways: IOS-direct digitalization using an Intra-Oral scanner (CS3600), cone-beam computed tomography scan (CBCT 1)-indirect digitalization of impression (CBCT-CS9300), CBCT 2-indirect digitalization of impression (CBCT-CS8100), and Extra-Oral scanner (EOS)-indirect digitalization of gypsum-cast (CeramillMap400). Accuracy of 3D datasets was evaluated in relation to a reference dataset by best-fit superimposition. Marginal fit of lithium disilicate crowns after grinding was evaluated by replica technique. Significant differences were detected for 3D accuracy by Mann-Whitney U and for fit of crowns by One-way ANOVA followed by Scheffe's post hoc (p = 0.05). RESULTS: 3D analysis revealed mean positive and negative deviations for the groups IOS (- 0.011 ± 0.007 mm/0.010 ± 0.003 mm), CBCT 1 (- 0.046 ± 0.008 mm/0.093 ± 0.004 mm), CBCT 2 (- 0.049 ± 0.030 mm/0.072 ± 0.015 mm), and EOS (- 0.023 ± 0.007 mm/0.028 ± 0.007 mm). Marginal fit presented the results IOS (0.056 ± 0.022 mm), CBCT 1 (0.096 ± 0.034 mm), CBCT 2 (0.068 ± 0,026 mm), and EOS (0.051 ± 0.017 mm). CONCLUSIONS: The marginal fit of EOS and IOS, IOS and CBCT 2, and CBCT 2 and CBCT 1 showed statistical differences. The marginal fit of CBCT 1 and CBCT 2 is within the range of clinical acceptance; however, it is significant inferior to EOS and IOS. CLINICAL RELEVANCE: The use of a CBCT enables clinicians to digitize conventional impressions. Despite presenting results within clinical acceptable levels, the CBCT base method seems to be inferior to Intra-Oral scans or to scanning gypsum models regarding the resulting accuracy and fit.

Virtual Simulation of Periodontal Surgery Including Presurgical CAD/CAM Fabrication of Tooth-Colored Removable Splints on the Basis of CBCT Data: A Case Report.

Innovative digital diagnostic, design, and manufacturing technologies combined with high-performance polymers offer new possibilities to facilitate complex interdisciplinary treatment procedures. This article reports on the interaction of different digital technologies, from presurgical digital simulation of periodontal surgery to final prosthodontic rehabilitation, in a case of amelogenesis imperfecta in a 17-year-old girl. The aim was to digitally determine the treatment outcome by three-dimensional simulation of the soft tissue removal and to create computer-aided design/computer-assisted manufacture tooth-colored splints before the clinical treatment. The case report shows the synergy of the combination of multiple digital technologies for a predictable periodontal and prosthetic treatment outcome.

Impact of background on color, transmittance, and fluorescence of leucite based ceramics.

This study evaluated the impact of tooth shade on differences in color (∆E), lightness (∆L), chromaticity coordinates a*/b* (∆a and ∆b), transmittance and the degree of fluorescence of CAD/CAM leucite based ceramic (LBC). Ten disks were fabricated of LBC; Empress CAD, A2, thickness of 1.5 mm and eight disks of resin-nano-ceramic (RNC; Lava Ultimate) in different colors to simulate variations in substrate shade. The associations of LBC disks with different color substrates were analyzed with a spectrophotometer; ∆E, ∆L*, ∆a*, ∆b*, and transmittance were measured and calculated. Fluorescence was evaluated with a fluorescence system (Fluorescence System, Biopdi). All substrate shades influenced the optical properties of LBC, with regard to color, luminosity, coordinate a* and b*, transmittance, and fluorescence (p<0.001). Substrate colors with high saturation (A3.5 and C2) presented highest impact, whereas colors with lowest saturations (BL, B1) showed less impact. Substrate color influenced the optical properties of ceramic restorations.

Transmission of light in the visible spectrum (400-700 nm) and blue spectrum (360-540 nm) through CAD/CAM polymers.

OBJECTIVES: CAD/CAM-fabricated long-term temporary restorations from high-density polymers can be applied for a wide range of indications. Milled from monolithic, mono-colored polymer blocks, the translucency of the material plays an important role for an esthetically acceptable result. The aim of this study was to compare the transmittance through visible light and blue light of CAD CAM polymers to a glass-ceramic material of the same color. MATERIALS AND METHODS: Ambarino High-Class (AM), Telio-CAD (TC), Zenotec PMMA (ZT), Cercon base PMMA (CB), CAD Temp (CT), Artbloc Temp (AT), Polycon ae (PS), New Outline CAD (NC), QUATTRO DISK Eco PMMA (GQ), Lava Ultimate (LU), and Paradigm MZ 100 (PA) were employed in this study using the feldspathic glass-ceramic Vita Mark II (MK) as control group. Using a spectrophotometer, the overall light transmittance was measured for each material (n = 40) and was calculated as the integration (t c (λ) dλ [10-5]) of all t c values for the wavelengths of blue light (360-540 nm). Results were compared to previous data of the authors for visible light (400 to 700 nm). RESULTS: Wilcoxon test showed significant differences between the light transmittance of visible and blue light for all materials. CONCLUSION: CAD/CAM polymers showed different translucency for blue and visible light. This means clinicians may not conclude from the visible translucency of a material to its permeability for blue light. This influences considerations regarding light curing. CLINICAL RELEVANCE: CAD/CAM polymers need to be luted adhesively; therefore, clinicians should be aware about the amount of blue light passing through a restoration.