Fracture resistance of CAD/CAM milled versus direct hand-made interim laminate veneers.

Background: Comparative studies of interim veneer restorations crafted using subtractive computer-aided manufacturing (s-CAM) milling technology and traditional direct hand-made approaches are needed. Purpose: This comparative in vitro study evaluated the fracture resistance of two types of provisional veneer restorations for maxillary central incisors: milled (s-CAM) and traditional direct hand-made bis-acryl veneers. Materials and methods: Fifty maxillary right central incisor veneers (25 specimens per group) were fabricated and divided according to the fabrication method: (1) s-CAM milled (Structure CAD, VOCO Dental); and (2) hand-made (Protemp Plus, 3M). The restorations were cemented onto 3D-printed resin dies using temporary cement and subjected to 1000 cycles of thermal cycling between 5° and 55 °C. These restorations subsequently were subjected to compressive loading until fracture occurred. Images of the fractured samples were captured using a scanning electron microscope (SEM). Statistical analysis was performed using the one-way ANOVA test and the Mann-Whitney U test. Results: Significant differences (p < 0.001) in the fracture resistance were observed between the two groups. s-CAM milled interim veneers displayed higher fracture resistance values (439.60 ± 26 N) compared to the traditional method (149.15 ± 10 N). Conclusion: The manufacturing method significantly influences the fracture resistance of interim veneer restorations. s-CAM interim laminate veneer restorations for maxillary central incisors exhibit a fracture resistance superior to that of the traditional method using bis-acryl.Clinical relevanceClinicians should consider CAD/CAM milled veneers for scenarios demanding long-term interim restoration and the withstanding of high occlusal forces.

The Influence of Thickness on Light Transmission for Pre- and Fully Crystallized Chairside CAD/CAM Lithium Disilicate Ceramics.

AIM: This in vitro study aimed to compare the light-transmission properties of two chairside CAD/CAM lithium disilicate (LD) ceramics (a novel fully crystallized and a traditional pre-crystallized) across varying thicknesses. MATERIALS AND METHODS: One hundred flat specimens were obtained from precrystallized (e.max CAD, Ivoclar Vivadent, Schaan, Liechtenstein) and fully crystallized (LiSi GC Block; GC, Tokyo, Japan) LD at five different thicknesses (0.5, 0.75, 1.0, 1.50 and 2.0 mm). All specimens were polished with a polishing system for lithium disilicate restorations following recommendations from the manufacturer. Light transmission was evaluated with a radiometer. The statistical analysis between e.max CAD and LiSi GC Block was performed using a Mann-Whitney test for each thickness at a significance level of 0.05 (p < 0.05), followed by a Kruskal-Wallis test to compare the light transmission between the thicknesses of e.max CAD and LiSi GC Block. RESULTS: Light transmittance was significantly affected by ceramic thickness. The 0.5 mm thick specimens exhibited the highest transmittance values compared to all other groups, while a light transmittance of 0.00 was observed in the 2.0 mm thick specimens for both e.max CAD and LiSi GC Block. In the comparison between e.max CAD and LiSi GC Block according to thickness, there was a statistically significant difference exclusively between groups with a thickness of 1.50 mm (p = 0.002). CONCLUSIONS: Light transmission for pre- and fully crystallized CAD/CAM lithium disilicate ceramics only showed a statistical difference at the thickness of 1.50 mm (p = 0.002). E.max CAD demonstrated acceptable light transmission up to a thickness of 1.5 mm. CLINICAL SIGNIFICANCE: A thickness of 2 mm for chairside CAD/CAM lithium disilicate ceramics, whether pre-crystallized or fully crystallized, necessitates the use of dual-cure resin luting cement due to reduced light transmission.

A Comparative Study of Shade-Matching Reproducibility Using an Intraoral Scanner and a Spectrophotometer.

BACKGROUND: We compared the repeatability of the shade determination of resin composite restorations and acrylic teeth in light and darker shades at baseline and after an aging process through two digital tooth color-matching methods: using a Trios 3Shape intraoral scanner and using a Vita Easyshade Compact spectrophotometer. MATERIAL AND METHODS: Forty upper central incisor acrylic teeth in the shade A1 (n = 10) and A3 (n = 10) were randomly assigned to be restored with Filtek Bulk Fill in the shade A1 (n = 10) or A3 (n = 10). Subsequently, 20 Class V cavities were prepared in a standardized manner (mesio-distal = 3.0 mm, cervical-occlusal = 2.0 mm, depth = 1.5 mm). Cavities were restored using an universal adhesive system and resin composite in two increments and were light-cured. The shade difference between the resin composite Class V restorations in acrylic teeth of the A1 and A3 shades was evaluated at baseline and after aging. Aging was simulated using ultraviolet light for 120 h. An Easyshade device and an intraoral scanner were used under D65 illumination. Measurements were taken five times, on top of the restoration and on the acrylic teeth, in a randomized manner. RESULTS: Data analysis was on the calculation of the arithmetic mean for the percentage of repeatability conducted by the Trios scanner and the Easyshade device. There was no statistically significant comparison between the shade measurement devices (p > 0.05). At baseline, the repeatability for both the Trios intraoral scanner and the Vita Easyshade Compact device for artificial teeth in the shades A1 and A3 was 100%. After aging, the trueness recorded by the intraoral scanner and the Easyshade device for artificial teeth in the shade A1 was 80%. For Class V restoration with shade A1, the intraoral scanner recorded 80% trueness and the Easyshade device recorded 60% trueness at baseline. For shade A3, the intraoral scanner recorded 60% trueness and the Easyshade device recorded 60% trueness. CONCLUSIONS: The intraoral scanner and Easyshade device are reliable for baseline shade selection, but their accuracy decreases after aging, particularly for darker shades.

Expediting the Rehabilitation of Severely Resorbed Ridges Using a Combination of CAD-CAM and Analog Techniques: A Case Report.

With the life expectancy increasing, there is a growing need for prosthetic dental treatments to restore the oral health, function, and quality of life of edentulous patients. Presently, only a few articles are available describing the oral rehabilitation of patients with severely resorbed ridges with milled complete dentures. This clinical case report provides a straightforward protocol consisting of a combination of analog and digital techniques for the rehabilitation of edentulous patients with severely resorbed ridges with milled fixed and removable complete dentures. This technique permits the minimization of the number of appointments, improves patient comfort, allows for the digital archiving of important clinical data, and permits the manufacture of prostheses with improved mechanical properties. These favorable outcomes were achieved by using the patient's existing PMMA complete denture as a custom tray for a final impression with light-bodied Polyvinylsiloxane. Subsequently, the resulting models were digitized, and a digital complete denture was designed and manufactured in an expedited manner using CAD-CAM techniques. Therefore, this case report highlights the potential of CAD/CAM technology to predictably restabilize oral functions and improve patients' quality of life.

Ceramic versus Composite Resin Polishing Systems on the Surface Roughness of Milled Leucite-Reinforced Ceramics.

Background and Objective: This study aimed to compare the surface finish of milled leucite-reinforced ceramics polished with ceramic and composite polishing systems based on the manufacturers' recommendations. Materials and Methods: Sixty subtractive computer-aided manufactured (s-CAM) leucite-reinforced glass-ceramic specimens (IPS-Empress-CAD) were assigned into six groups: no polishing, a ceramic polishing kit, and four composite kit groups. The roughness average (Ra) was evaluated in microns using a profilometer, and scanning electron micrographs were obtained for qualitative analysis. A Tukey HSD posthoc test (α = 0.05) was used to determine significant intergroup differences. Results: After surface evaluation of the ceramics, the Ra values of the polishing systems ranked OptraFine (0.41 ± 0.26) < Enhance (1.60 ± 0.54) < Shofu (2.14 ± 0.44) < Astropol (4.05 ± 0.72) < DiaComp (5.66 ± 0.62) < No Polishing (5.66 ± 0.74). Discussion: Composite polishing systems did not provide as smooth surfaces as the ceramic polishing kit for CAD-CAM leucite-reinforced ceramics. Thus, using ceramic polishing systems, polishing leucite ceramics is recommended, whereas composite polishing systems should not be considered as an alternative for use in minimally invasive dentistry.

Additive Wax-Up and Diagnostic Mockup As Driving Tools for Minimally Invasive Veneer Preparations.

This report describes the importance of and outlines steps for additive wax-up and diagnostic mockup for anterior teeth as diagnostic and driving tools for non-prep and minimally invasive veneer preparations. A 35-year-old male presented to the clinic with the chief complaint of spaces between his front teeth. Diagnostic additive wax-up provided the possibility of offering minimally invasive preparations, and the use of a diagnostic intraoral mockup fulfilled the patient's esthetic demands for treatment approval. Veneer preparations over the diagnostic mockup were provided as they are minimally invasive. Ceramic veneers were hand-crafted following the previous diagnostic wax-up, and restorations were bonded under rubber dam isolation. Overall, additive wax-up provides information needed to know if minimally invasive veneer preparations are possible, and the diagnostic mockup displays a physical, tentative outcome for the patient's evaluation before irreversible tooth preparations. These simple, but effective, techniques can drive the diagnosis and prognosis of minimally invasive veneer restorations.