RESUMEN
BACKGROUND: The aim of this systematic review was to analyze the types of human chewing simulator described in scientific literature. MATERIAL AND METHODS: An electronic search was conducted in the databases PubMed, Embase and Scopus. The search strategy included 10 search terms: "in vitro"; "dental materials"; "shear strength"; "fatigue fracture"; "bite force"; "prosthetic materials"; "chewing simulator"; "chewing machine"; "simulated mastication"; and "dental wear simulator." Two researchers worked independently to assess the titles and abstracts of the articles. The quality of the in vitro trials selected was evaluated by means of the Consolidated Standards of Reporting Trials scale. RESULTS: The electronic search identified 80 articles related to the topic of interest. After reading the full texts, ten works were selected. The articles focused mainly on the design of chewing simulators. Most of them were considered of moderate quality. Regarding the characteristics that an ideal chewing simulator should encompass, the devices described in articles varied greatly in terms of movement, periodontal ligament simulation, force sensors, and the materials tested. CONCLUSIONS: No chewing simulator offers all the characteristics necessary to reproduce human masticatory movements and forces under the humidity and pH conditions of the oral cavity. A simulator that encompasses all these characteristics would make it possible to standardize trials involving simulated mastication. Key words:In vitro, dental materials, dental wear simulator.
RESUMEN
STATEMENT OF PROBLEM: Because of market demand for innovation, new restoration materials have been introduced without adequate testing; clinical failure may be the consequence, and clinical studies are needed. PURPOSE: The purpose of this clinical study was to evaluate the biological and mechanical clinical behavior of implant-supported resin-modified ceramic crowns compared with that of metal-ceramic crowns. MATERIAL AND METHODS: Forty-two participants aged between 35 and 65 years received single implants in posterior edentulous sites. After the osseointegration period, half of the implants (selected randomly) (n=25) were restored with metal-ceramic crowns (MC group) and the other half with resin-modified ceramic crowns (RMC group) bonded with dual-polymerized resin cement onto titanium abutments. The biomechanical state of the restorations and implants was analyzed. RESULTS: Mean peri-implant bone loss after 5 years of functional life was 0.3 ±0.6 mm. The implant clinical survival rate was 98%. RMC crowns had a survival rate of 70%, whereas MC crowns had a 100% survival rate. RMC crowns had more mechanical complications than the MC group (P<.001). Peri-implant bone loss showed no significant differences between crown type (P=.175). CONCLUSIONS: All peri-implant bone loss values were within the range considered acceptable. Metal-ceramic crowns showed better mechanical behavior than resin-modified ceramic crowns. Biological responses of peri-implant tissue would appear to be independent of the type of cemented crown.