Silane in rebonding of orthodontic metal attachments

The present study was based on clinical experience that, with silane/adhesive system, reliable rebonding of metal orthodontic attachments can be created. From the statistical summary of the data of this study, it is safely concluded that, silane/adhesive rebonding technique demonstrated a reasonably reliable clinical procedure for the direct rebonding of loose and repeat use of debonded metal brackets. Silane/adhesive system can be used for direct bonding of metal orthodontic attachment to acrylic tooth or crown

Tensile fracture of soldered and unsoldered stainless steel wires

This study was designed to investigate the effect of heating on the breaking tensile strength of soldered and unsoldered stainless steel orthodontic wires, together with micrographic photography of the etched surfaces compared to "as-received". All heated or soldered wires had fractured under stress at the area in the wire, which had been heated. No fracture occurred in the soldered portion of the wires. Photographic micrography revealed that the heated wire had undergone pitting and other structural alterations, which had caused the wire to become weak and subsequently fracture. The wires had lost their wrought strength properties when exposed to the high temperatures used in soldering and, as a result, were less able to withst and the tensile forces exerted. The clinical significance is that heat necessary for flame soldering of orthodontic wires will likely cause a significant reduction in the useful properties of that wire

Mechanical properties of orthodontic wires

The present study was designed to compare the mechanical properties of two sizes of stainless steel, nickel-titanium [Nitinol] and cobalt-chromium [Elgiloy]. Wires were tested as received for yield strength, modulus of elasticity, recoverable stored energy, stored energy till the proportional limit and spring rate based on data collected from moment-deflection curves. The spring rate evaluation indicated that, the bigger the wire the stiffer it is with rectangular stainless steel wires the stiffest, then Elgiloy and Nitinol. As for stiffness, Nitinol is the easiest to bend, followed by stainless steel then Elgiloy; hence it will be able to store and release elastic energy. Patients comfort will be anticipated with the use of wires with low modulus of elasticity, which produce continuous, light force as compared with stainless steel and Elgiloy strong force

effect of silicone mold liner on compressive properties of dental gypsum

The study was conducted to evaluate the use of silicone rubber base as mould material combined with gypsum, stone, plaster and mixture of both. Specimens were prepared and tested for compression elastic modulus, compression deformation%, and elastic limit, with and without rubber discs of different thickness. The results showed that in spite of the addition of 2-4 mm thick silicone rubber material to the gypsum, the recorded values were superior compared with control results. Hence, the use of silicone rubber material as lining for gypsum during curing of acrylic resins will be expected to be markedly superior to that of the usual method of processing in split moulds made of gypsum products. Further studies are needed to determine the practicability of curing acrylic resins, with different bulks, using this technique

Direct bonding to ceramic fused-to metal crown, scanning electron microscope study

The data analyses and the scanning electron microscope examination in this study provided strong support to the following conclusions: Saline/adhesive system in direct bonding to ceramo-fused to metal crowns produced comparable bond resistance to that to porcelain denture teeth; tensile pull debonding force is recommended to minimize microfractures and porcelain tears; intra-oral polishing technique must be proposed to restore the porcelain surface glazing