The aim of this study was to investigate the biomechanical interactions between cuspal preparation designs and cement thickness in a cusp-replacing ceramic premolar restoration. The cavity was designed in a typical MODP (mesial-occlusal-distal- palatal) restoration failure shape when the palatal cusp has been lost. Twelve 3D finite element (FE) models with four cavity preparations (without coverage and with buccal cuspal coverage in 1.0, 1.5 and 2.0 mm reducing in cuspal height) and three cement thicknesses (50, 100 and 150 microm) were constructed to perform the simulations. The results indicated that enamel and cement stresses in designs with no buccal cusp replacement or a 1.0 mm thick buccal cusp replacement were higher than the designs with 1.5 and 2.0 mm thick replacement. No apparent differences were found in the dentin, enamel, and cement stresses based on cement thicknesses of 50, 100, or 150 microm. This study concluded that when cusp replacement is indicated, reduction of the buccal cusp by 1.5 mm at least could reduce stress.

This research developed a feedback control system of laser compensation for the rapid prototyping (RP) machine using layer-wise slurry deposition and selective laser sintering (SLS). The slurry was prepared by silica power and silica sol with 60 and 40 wt.% with suitable rheological properties for 0.1 mm layer deposition. Four ceramics for comparison of the formability of fabricated ceramic green parts with/without the feedback control system of laser energy density for models were designed With this laser feedback control, batter quality ceramic green parts can be manufactured and the rapid prototyping machine with steady laser energy radiated on slurry layer was achieved. Experimental results validate the well performance of the measuring laser power and feedback control system.

In this work, a hydroxyapatite (HA) bioceramic and a silica binder were used as the raw materials for manufacturing bioceramic bone scaffold after sintering by a laser beam in a home-made 3D Printing (3DP) machine. Results indicate that the bending strength of the scaffold can be improved after heat-treatment. While simultaneously increasing surface roughness conducive to osteoprogenitor cell adhesion. The processing parameters of a 90 mm/s laser scanning speed, 12 W of laser energy and 10 kHz of scanning frequency were used to fabricate a porous scaffold model, which possesses suitable biocompatibility and mechanical properties, allowing adhesion and proliferation of bone cells. Therefore, this process has great potential for manufacturing bone scaffolds.

Retention of veneering materials to the tooth influences the survival rate in which depends primarily on an adequate adhesive bonded to enamel and ceramic substrates. Microleakages associated with resin monomers penetrating in enamel–etched porosities arise as the key issue to cause crack propagation and induce de-bonding in adhesive layer. The aim of this study is to investigate the micromechanical responses and crack propagation in a ceramic veneer adjacent to an incisal-overlapped incisor using the finite element (FE) submodeling and the element deactivation techniques. Section contours of an intact maxillary central incisor were acquired from microcomputed tomography (CT) to construct a three-dimensional (3D) FE macromodel considered with butt joint veneer design using mapping mesh approach. Ten loads from 10 to 100 N increments with 10 N were applied with an angulation of 60° to the tooth longitudinal axis at the incisal edge in the macromodel as the loading conditions to perform the simulations. The micromodel was constructed at an enamel–adhesive interface, where was the stress concentration area in the macromodel. The morphology and dimensions of the resin tags at the interface were assigned based on a SEM micrograph. Boundary conditions of the micromodel were determined from the macromodel results. An iterative code with the element deactivation technique was used while the local element stresses exceeding a self-testing tensile strength in adhesive layer to simulate the microcrack propagation. Stress concentration within the adhesive occurred at the enamel–adhesive interface of the lingual edge from the macromodels findings and at their resin tags base from the micromodels results. The maximum stress value in the micromodel exceeded the tensile strength (11.8 MPa) of resin cement when loading condition was 50 N. A simulated fracture path was found at the resin tags base along the enamel–adhesive interface from lingual to labial side. This study indicated that the FE submodeling and the element deactivation techniques could simulate efficiently the micromechanical responses and the microcrack propagation noted at the enamel–adhesive interface in the veneer system.

In this paper, the hydroxyapatite (HA) based bioceramic materials were used in a rapid prototyping (RP) system to fabrication bioceramic bone scaffold for tissue engineering (TE) using an additive manufacturing (AM) technology. When the bioceramic slurry is sintered via the processing parameters of an 85 mm/s laser scanning speed, 24.5 W of laser power, 10 kHz of scanning frequency, and 2500 Cp of slurry viscosity, a porous bone scaffold can be fabricated under a lower laser power energy. Results indicate that the bending strength of the scaffold was 14.2 MPa, which could be improved by heat-treatment at 1200 °C for 2 hour. MTT method and SEM observations confirmed that the fabricated bone scaffolds possess suitable biocompatibility and mechanical properties, allowing smooth adhesion and proliferation of osteoblast-like cells. Therefore, the fabricated bone scaffolds have great potential for development in tissue engineering.