Brittleness index and its relationship with materials mechanical properties: Influence on the machinability of CAD/CAM materials.

The aim of this study is to evaluate the machinability of four CAD/CAM materials (n = 13) assessed by brittleness index, Vickers hardness, and fracture toughness and interaction among such mechanical properties. The materials selected in this in vitro study are Feldspathic ceramic [FC], Lithium-disilicate glass ceramic [LD], leucite-reinforced glass ceramic [LR], and nanofilled resin material [RN]. Slices were made from the blocks following original dimensions 14 × 12 × 3 mm (L × W × H), using a precision slow-speed saw device and then surfaces were regularized through a polishing device.

Effect of storage and aging conditions on the flexural strength and flexural modulus of CAD/CAM materials.

Computer-aided design/computer-aided manufacturing (CAD/CAM) materials were submitted to thermocycling, to identify changes in mechanical behavior. Four CAD/CAM materials were divided in four subordinate groups (n=9): (1) dry out for 7 days, (2) distilled water at 37C for 7 days, (3) 60,000 thermocycles, and (4) 120,000 thermocycles. Following thermocycling, samples were submitted to three-point bending test.

CAD/CAM diamond tool wear.

Objective: This study evaluated the wear of computer-aided design/computer-assisted manufacture (CAD/CAM) burs and the morphologic changes after a number of millings.

Method And Materials: Diamond burs (cylinder and step-bur) were divided into four milling groups: zero millings (G0); 15 millings (G1); 25 millings (G2); and 35 millings (G3). Seventy-five premolar crowns were milled using the Cerec Compact Milling unit and VitaBlock Mark II.

Effect of thermal cycling on fracture toughness of CAD/CAM materials.

Purpose: To compare the fracture toughness of four different CAD/CAM materials, (VM) Vitablocs Mark II, (IP) IPS e.max CAD, (LU) LAVA Ultimate, and (VE) Vita Enamic under long thermocycling conditions.

Methods: Each type of ceramic block was sectioned into beams (n=9) with dimensions of 14×3×2.

Can Tooth Preparation Design Affect the Fit of CAD/CAM Restorations?

Objective: The purpose of this study was to evaluate if the marginal fit of computer-aided design and computer-aided manufacturing (CAD/CAM) restorations manufactured with CAD/CAM systems can be affected by different tooth preparation designs.

Methods: Twenty-six typodont (plastic) teeth were divided into two groups (n = 13) according to the occlusal curvature of the tooth preparation. These were the group 1 (control group) (flat occlusal design) and group 2 (curved occlusal design).

Microtensile bond strength between a UDMA fiber post and different resin cements: Effect of pre-surface treatment.

During a fiber post cementation, bonding failure often occurs at the junction between the fiber-post and resin-cement. Because this failure requires better characterization, we evaluated if different post surface treatment can affect the bond strength of urethane dimethacrylate (UDMA) fiber-posts with resin-cements. Three groups were created: G1: no treatment/silane; G2: ethyl alcohol (96° GL)/silane; G3: 24% HO/silane and further divided into four subgroups: I-Unicem/3MESPE; II-BisCem/Bisco; III-Panavia SA/Kuraray and IV-DuoLink/Bisco.

Dentistry students' perceptions about an extramural experience with a Brazilian indigenous community.

Objective: The aim of the present study was to evaluate dentistry students' perceptions about an extramural activity designed to deliver dental care to an indigenous community.

Materials And Methods: This was a qualitative investigation involving 4 students of dentistry who had just had the experience of delivering treatment to indigenous Brazilian people. These students answered questions about the relevance of the experience to their personal and professional lives.