Biomedical Engineering Reference
In-Depth Information
For orthodontics, which is relevant to the subject of this topic, we
discuss the archwire application of NiTi materials.
As it was mentioned in the previous section, the corrosion of
NiTi materials may be accelerated by various factors such as
electrolyte environment and surface quality. This situation may
lead to precocious damage by fatigue mechanism. Corrosion may
occur and change the surface state of the material by increasing
its roughness. It can result, for example, in the inappropriate
force distribution by increasing the friction between the bracket
and archwire, which is important in this speciic application (see
Table 8.2).
Table 8.2
Numerical force value for optimal tooth movement (by
permission of DENTSPLY GAC)
Medium
length roots Long roots
Mandibular incisors 50-55 g 55-65 g 65-70 g
Mandibular canines 85-95 g 95-110 g 110-130 g
Mandibular premolars 70-80 g 80-90 g 90-100 g
Maxillary irst molars 280-300 g 300-320 g 320-360 g
Maxillary incisors 65-75 g 75-85 g 85-95 g
Maxillary lateral incisors 60-65 g 65-70 g 70-80 g
Maxillary canines 105-115 g 115-130 g 130-170 g
Premolars, single roots 85-100 g 100-115 g 115-135 g
Premolars, multiroots 100-110 g 120-130 g 130-140 g
Mandibular
irst molars 230-250 g 250-270 g 270-320 g
Teeth
Short roots
Oral cavity should be treated as a changeable environment
[43]. Diet, drug use, stress, hygiene, and others factors inluence
the pH volume, which may varies from 5.2 to 7.8, saliva osmolarity
depending on protein concentration and the level of ionized sodium
potassium and chloride, temperature from cold ice to hot tea and
plaque state.
All these extreme factors play a signiicant role in non-hostile
oral cavity environment. That is why proper material selection for
archwire application is so important (Table 8.3).
