Comparison of efficacy and usability of custom mandibular advancement devices fabricated with the conventional method and digital workflow: A pilot clinical study.

PURPOSE: To compare the effects of fabricating methods of custom monoblock mandibular advancement devices (MADs) on usability and efficacy in patients with mild and moderate obstructive sleep apnea (OSA). MATERIALS AND METHODS: Digitally fabricated custom MADs (dMADs) were produced for 11 OSA participants who had previously used conventionally fabricated custom MADs (cMADs). The participants answered a modified usability questionnaire for both MADs, and the average scores that were given to the questionnaire were evaluated by age, sex, and body mass index (BMI), and the scores of cMADs and dMADs were compared. After 6 months of usage of each MAD, the apnea-hypopnea index (AHI), mean and lowest oxygen saturations, and total sleep time were measured for efficacy assessment. Data were analyzed with Cronbach's alpha, Mann-Whitney U, Kruskal-Wallis, Wilcoxon signed-rank, one-way repeated measures analyses of variance, and Bonferroni tests (α = 0.05). RESULTS: Cronbach's alpha was found at 0.834 and 0.722 for the conventional and digital questionnaires, respectively. The usability scores of the dMADs were significantly higher than those of cMADs (p = 0.013). There was no difference in usability scores in terms of sex or BMI (p > 0.05). No statistically significant difference was found for cMAD (p = 0.113) among age groups; however, there was a significant difference for dMAD (p = 0.046). The AHI, mean, and lowest oxygen saturation values were significantly affected by MAD usage (p < 0.001). However, total sleep time values did not differ after the MAD treatments (p > 0.05). Significantly lower AHI and significantly higher lowest oxygen saturation values were observed with dMAD, while both appliances led to similar results for mean oxygen saturation and total sleep time values (p > 0.05). CONCLUSIONS: Participant usability scores were higher for digitally manufactured MADs than conventionally manufactured MADs. However, both conventional and digital MADs were found effective in decreasing the AHI levels and increasing the mean and lowest oxygen saturation values of the participants.

Fabricating a custom monoblock mandibular advancement device by using an open-source nondental CAD software program and additive manufacturing: A dental technique.

Custom mandibular advancement devices (MADs) can be fabricated by using either conventional processes or computer-aided design and computer-aided manufacturing (CAD-CAM). The CAD-CAM technique involves digitizing the dental arches of the patients, designing by using a dental CAD software program, and additive manufacturing with a suitable material. This article describes the steps of the design of a custom MAD by using an open-source nondental CAD software program and of the fabrication with additive manufacturing.

Design and fabrication of an interim fixed restoration with an open-source nondental CAD software program and additive manufacturing: A technical report.

This technique aimed to identify the potential of an open-source software program and to present the design and fabrication procedures of a single interim crown with a nondental CAD software program. The steps included defining the margins, establishing the cement interval value, completing the virtual modeling of the crown, and checking the proximal and occlusal contacts by using color mapping.

Effects of sintering protocol and dipping time on the optical properties of monolithic zirconia.

STATEMENT OF PROBLEM: The use of monolithic zirconia for restorations has become popular. However, the effects of the coloring process and sintering procedure on the optical properties of monolithic zirconia remain unclear. PURPOSE: The purpose of this in vitro study was to evaluate the effects of the different sintering protocols and dipping times on the CIELab color parameters, color difference (ΔE00), translucency parameter (TP00), opalescence parameter (OP), and contrast ratio (CR) of monolithic zirconia. MATERIAL AND METHODS: One hundred and fifty monolithic zirconia specimens were prepared and divided into 5 groups according to different dipping times in A2 shade coloring liquid: no immersion (D0), 3 minutes (D3), 5 minutes (D5), 7 minutes (D7), and 9 minutes (D9). The specimens were further divided into 3 subgroups according to different sintering protocols (n=10): classic (C); speed (S); and super-speed sintering (SS). The CIE L∗a∗b∗ values, ΔE00, TP00, OP, and CR values were determined with a spectrophotometer. The data were analyzed with 2-way ANOVA and Bonferroni post hoc tests (α=.05). RESULTS: The effects of the sintering protocol, dipping time, and interaction of the sintering protocol and dipping time were significant for the L∗, a∗, b∗, ΔE00, TP00, OP, and CR parameters (P<.001). The ΔE00 values of the SS groups were significantly higher than those of the C and S groups for all the dipping times assessed. However, only the CD3 and CD5 groups had ΔE00 values below the acceptability threshold (<1.8). Coloring significantly reduced TP00 values and significantly increased OP and CR values in the colored groups compared with those in the D0 groups. The C and S protocols for different dipping times showed similar optical properties in TP00, OP, CR, and ΔE00 (excluding the D0 and D9 groups) compared with the SS protocol. CONCLUSIONS: Different sintering protocols combined with various dipping times significantly affected the optical properties of monolithic zirconia. However, C and S sintering with a 3-minute and 5-minute coloring process yielded more favorable optical results than SS sintering and prolonged dipping times.

Effect of fabrication techniques on the optical properties of zirconia-based systems.

STATEMENT OF PROBLEM: How the optical properties of zirconia restorations are affected by their differing processing techniques is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the effects of 5 different fabrication techniques on the optical properties of zirconia-based systems, including the color difference between the corresponding shades (ΔE∗ab, ΔE00), translucency parameter, opalescence parameter, and fluorescence (ΔE∗ab-FL). MATERIAL AND METHODS: Sixty zirconia disks (IPS e.max ZirCAD) were prepared (0.5 ±0.01mm thick) and veneered by using different techniques (n=15): Group L - layering with fluorapatite ceramic; Group P - pressing with fluorapatite ceramic; Group CB - veneered with pressing followed by layering technique; Group CO - digitally veneered with lithium disilicate glass-ceramic; and Group FZ - prepared from monolithic zirconia (inCoris TZI) (n=15). All the specimens were set to 1.5 ±0.02 mm in thickness. Color measurements were made with a spectrophotometer. Data were statistically analyzed with 1-way ANOVA and the Tukey honestly significant difference, Kruskal-Wallis, Bonferroni (α=.05), Pearson, and Spearman correlation tests (α=.01). RESULTS: Significant differences were found among the groups for all the optical parameters (P<.05). All the groups showed color differences higher than the perceptibility and acceptability thresholds for ΔE∗ab and ΔE00, except the P and FZ groups that showed values lower than the acceptability threshold (ΔE∗ab<2.7). Translucency parameter, opalescence parameter, and ΔE∗ab-FL values ranged between 5.77 and 9.95, between 4.72 and 7.07, and between 1.93 and 3.14, respectively. Strong positive correlations were found between ΔE∗ab and ΔE00, as well as between translucency parameter and opalescence parameter (P<.001). CONCLUSIONS: The optical properties of the zirconia-based systems were significantly affected by the fabrication techniques even when the same nominal shade was used. Therefore, the color reproduction, translucence, opalescence, and fluorescence of the selected materials should be considered for acceptable color matching.

Effect of Veneering Techniques on Shear and Microtensile Bond Strengths of Zirconia-Based All-Ceramic Systems.

PURPOSE: To evaluate shear (SBS) and microtensile (µTBS) bond strengths of zirconia cores veneered using different fabrication techniques. MATERIALS AND METHODS: Seventy-five IPS e.max ZirCAD plates were fabricated and divided into three groups according to the following veneering techniques: layering, pressing, and CAD-on. The specimens of the layering group were veneered with IPS e.max Ceram, and the specimens of the pressing group were veneered with IPS e.max Zir- Press. Veneering ceramics in the CAD-on group were milled from IPS e.max CAD, fused with the core by using a glass-fusion ceramic, and then crystallized. Bond strength tests were performed using a universal testing machine at a crosshead speed of 0.5 mm/min for the SBS test and 1 mm/min for the µTBS test. Mean SBS and µTBS (MPa) were analyzed with one-way ANOVA and Tukey's HSD test (p < 0.05). RESULTS: Significant differences in SBS were observed between the groups (p < 0.05). The mean SBS for the CAD-on group was significantly higher (31.89 ± 5.83 MPa) than those of the layering (14.27 ± 4.45 MPa) and pressing (12.23 ± 3.04 MPa) groups. However, the mean µTBS of the CAD-on (30.41 ± 8.64 MPa), layering (21.71 ± 3.40 MPa) and pressing (20.74 ± 6.36 MPa) groups were not statistically significant (p > 0.05). CONCLUSION: The CAD-on technique showed the highest shear bond strengths of the tested groups, and most of the specimens failed cohesively instead of failing at the adhesive interface.

Effect of Different Surface Treatments on the Bond Strength of Lithium Disilicate Ceramic to the Zirconia Core.

OBJECTIVE: The aim of this study was to evaluate the effect of different surface treatments [sandblasting, Erbium:Yttrium-Aluminium-Garnet (Er:YAG), and femtosecond lasers] on the shear bond strength (SBS) of the CAD-on technique. BACKGROUND DATA: Although demand for all-ceramic restorations has increased, chipping remains one of the major problems for zirconia-based restorations. MATERIALS AND METHODS: Forty yttrium-stabilized tetragonal zirconia polycrystalline (Y-TZP) zirconia plates (IPS e.max ZirCAD, Ivoclar Vivadent) were cut, sintered (12.4 × 11.4 × 3 mm) and divided into four groups according to the surface treatments (n = 10): a control group with no surface treatment (Group C), sandblasting with 50 µm Al2O3 (Group S), Er:YAG laser irradiation (Group E), and femtosecond laser irradiation (Group F). Also, 40 cylindrical (5 mm diameter, 2 mm height) lithium disilicate (IPS e.max CAD) veneer ceramics were cut and fused to all zirconia cores by a glass-fusion ceramic and crystallized according to the CAD-on technique. Specimens were subjected to shear force using a universal testing machine. The load was applied at a crosshead speed of 0.5 mm/min until failure. Mean SBS (MPa) were analyzed with one way ANOVA (p < 0.05). The failed specimens were examined under a stereomicroscope at ×20 to classify the mode of failure. RESULTS: The highest SBS was observed in Group F (36 ± 3.31 MPa), followed by Group S (33.03 ± 5.05 MPa), and Group C (32.52 ± 10.15 MPa). The lowest SBS was observed in Group E (31.02 ± 4.96 MPa), but no significant differences were found between the control and surface treated groups (p = 0.377). All the specimens showed a mixed type of failure. CONCLUSIONS: Femtosecond laser application increased the bond strength between zirconia-veneer specimens. However, the novel CAD-on technique with no surface treatment also showed high bonding strength. Thus, this technique could prevent ceramic chipping without additional surface treatments.

Color Stability of CAD/CAM Fabricated Inlays after Accelerated Artificial Aging.

PURPOSE: To investigate the influence of accelerated artificial aging on the color stability of three different inlay restorations produced with a CAD/CAM system. MATERIALS AND METHODS: Thirty non-carious human mandibular molar teeth were used. The teeth were embedded in autopolymerizing acrylic resin blocks. Standard Class I inlay cavities were prepared, and the teeth were randomly divided into three groups (n = 10) to fabricate inlay restorations: (1) a feldspathic-ceramic group, (2) a resin nano-ceramic group, and (3) a leucite glass-ceramic group. Optical impressions were made with CEREC software, and the restorations were designed and then milled. The inlays were adhesively cemented with a dual-polymerizing resin cement and left in distilled water at room temperature for 1 week. Color measurements were performed with a spectrophotometer before and after accelerated aging in a weathering machine with a total energy of 150 kJ/m(2) . Changes in color (∆E, ∆L, ∆a, ∆b, ∆C) were determined using the CIE L*a*b* system. The results were assessed using a one-way ANOVA and Tukey's HSD test (p = 0.05). RESULTS: The color changes of the materials ranged from 2.1 to 9.29. The highest color change was seen in the resin nano-ceramic material. This change was not clinically acceptable (∆E > 5.5). No significant differences were found in the ∆L and ∆a values of the test groups. CONCLUSIONS: Color changes were observed in each evaluated material after accelerated aging. All CAD/CAM inlays became darker in appearance, more saturated, a little reddish, and more yellow.