Dogodek

Predavanja »The characteristics of shape memory NiTi orthodontic wires and titanium in the biological environment of the mouth«

Datum in ura

13.7.2017, ob 10.00

Prostor

B-013

Predavatelj

Doc. Dr. Valentina Veselinović

Podjetje

Univerza v Banja Luki, Medicinska fakulteta, Bosna in Hercegovina

Naslov predavanja

The characteristics of shape memory NiTi orthodontic wires and titanium in the biological environment of the mouth

Kratek povzetek predavanja

Titan and its alloys have wide use in all fields of dental medicine. Ni-Ti wires are often used in orthodontic clinical practice due to their low modulus of elasticity and wide force-delivery range.  The wide applicability of this material is based on two special properties, derived from a martensitic/austenitic phase transformation: The Shape-Memory Effect (SME) and the Super-Elasticity (SE). NiTi austenitic wire can "remember" its shape - the shape of an ideal wire arch. Decreasing  the temperature, the alloys are transformed into a martensitic form in which it is possible to bend and shape it to the  desired form. Every time the temperature rises above the austenitic finish temperature, the alloy is transformed into its austenitic shape, or returns to the original shape of the ideal arch  (one way memory effect ) and remembers only one form of two possible forms of the wire arch- in this case austenitic. Contemporary technology provides accurate transitional temperature determination (TR). With this kind of NiTi alloy TR is very close to the temperature of the oral cavity (usually it ranges from 35 ° C to 40 ° C). This allows the formation of wire at room temperature. As soon as the temperature of the wire in the mouth increases, the transformation takes place in austenitic form. In this way, we are able to form the wire in the austenitic phase, cool it  to the martensite, and, in that condition, set it in to brackets. After returning to the body temperature the wire strives to achieve the shape it has memorized in the austenic phase. The above-mentioned mechanism of action has the effect of continuous, controlled force on the teeth and allows them to move in the desired direction. Familiarity with the phase structure and the choice of adequate material for each clinical situation is crucial for successful and controlled orthodontic therapy monitoring.
Endosteal implants, whose  role is effective root replacement, are created mostly of titanium. Although possessing exceptional biocompatibility and ability of osseointegration,  their mechanical properties are incompatible with the biomimetic principles of contemporary dentistry, as missing  tissues in the oral cavity should be replaced with materials of similar properties. Although the implant represents an effective replacement for the root of the teeth, unlike the natural tooth, the titanium implant is ankylotically osseointegrated to the bone, does not possess periodontal supporting ligaments  and, therefore, its mechanism of adaptation and amortisation  of occlusal forces is minimal. Any overload of the implant, caused by inadequate prosthetic reconstructions, leads to generating tension  in the implantoprotetic complex, which can result in bone resorption, replacement fracture, or even fracture of the implant itself. It is necessary to combine clinical knowledge and good knowledge of materials science to understand the behaviour of building materials in the oral cavity better and reduce the possibility of therapeutic complications.

Pri predmetu

/

V okviru Inštituta/katedre/laboratorija

Inštituta za tehnologijo materialov, doc. dr. Rebeka Rudolf

 

 Vabilo na predavanje (352 KB)