Abstract
The impact of five different water/powder (w/p) ratios in the characterization of high strength dental stone was evaluated, since the recommendations of the gypsum' manufacturers are not always correctly followed by the dental prosthesis technicians. Fiber Bragg grating (FBG) sensors were used to measure the setting expansion and temperature variation which occurred during the setting reaction for each w/p ratio, as well as the thermal expansion coefficient. Thick mixtures with low w/p ratios had more crystals impinging upon each other during crystal growth, resulting in more expansion and more heat released. This thermal behavior was only achieved to w/p ratios within the manufacturer-recommended mixing ratio range. The results also revealed the existence of boundary condition; this corresponding to the limit of the mixing ratio recommended by the gypsum' manufacturer. Data provided in this study are particularly important for dental technicians with a view to attaining the best results in accuracy of fit for their prosthetic works.

Abstract

Abstract
The use of fibre Bragg grating sensors to study dental materials like resin-based composite and gypsum products is reported. Two commercially available composite resins and three types of gypsum products were tested in order to determine polymerization contraction and setting expansion. Temperature and strain evolution during the hardening phase of the material were also obtained. The presented technique can be a good tool for dentists in order to better manipulate a material and predict how it will behave in vivo.

Abstract
This paper describes the use of fibre Bragg grating (FBG) sensors to measure strains at a mandible surface that are caused by static or impact loads on a dental implant. The measuring apparatus uses a fixed optical filter reference scheme and is able to detect dynamic signals with frequency components of up to 10 kHz. A dried implanted cadaveric mandible was used with strain gauges and FBG sensors placed at the outer surface in the direction of the longitudinal axis of the implant. The implants were loaded statically and dynamically and uniaxial strains recorded. The study demonstrates the ability of the FBG as a biomechanical sensor.

Abstract

Abstract
This paper describes an experimental study that aimed at determining the mandibular strains provoked by impact loads on conventional and non-conventional dental implant systems. The novel implant differs from typical commercial designs because it comprises an elastomeric material barrier (stress shock absorber) interposed between the implant and an artificial crown. A dried implanted cadaveric mandible with strain gauges placed at the inner and outer surfaces in the direction of the implant axis was used. The implants were loaded dynamically and uniaxial strains recorded. Overall, the results showed that an interposing flexible material between the crown and the top surface of the implant attenuates the load, avoiding high peak loads, which can occasionally occur from non-physiological occlusion loads that can be transferred to the surrounding bone tissue.