Lecture 7 Flashcards
what type of orthodontic wire is strong, stiff, formable, and has been used routinely for many years?
stainless steel
what type of orthodontic wire is softer than stainless steel, making it more formable, and then the wire can be heat treated to make it harder before it is inserted into the orthodontic appliance?
chromium alloys (elgiloy)
what type of orthodontic wire is very useful during the initial stages of orthodontic alignment due to its exceptional ability to apply light force over a large range of activations, and its shape memory and superelasticity?
nickel-titanium alloys
which type of NiTi alloy wires regain their original shape after being exposed to heat?
heat activated NiTi wires
which type of NiTi alloy wires can be deformed and will rebound back to their original shape?
superelastic NiTi wires
what is a weakness of NiTi alloy wires?
they have poor formability
what type of orthodontic wire offers a highly desirable combination of strength and springiness as well as good formability, whose properties fall in between stainless steel and NiTi alloys
beta-titanium (TMA)
orthodontic appliances should not be reactivated more frequently than ___
3-week intervals
why shouldn’t orthodontic appliances be reactivated any sooner than at 3 week intervals?
undermining resorption typically requires 7-14 days and tooth movement is essentially complete in this length of time, but there is an equal or longer period for PDL regeneration and repair that should be observed before force is applied again
what might happen if an orthodontic appliance is activated too frequently?
it can short circuit the repair process and can produce damage to the teeth and/or bone that a longer appointment interval would have prevented or would have at least minimized
since the presence of orthodontic appliances increases the amount of gingival inflammation, even with good oral hygiene, loss of alveolar bone height might seem likely. however, it is almost never a complication of ortho treatment. why?
- the position of the teeth determines the position of the alveolar bone
- when teeth erupt or are moved, they bring bone with them, so crestal bone loss from ortho treatment is rarely seen
usually, as a result of ortho treatment, bone loss averages ___ with the greatest incidences at ___
- less than 0.5mm and rarely exceeds 1mm
- extraction sites
bone loss is almost never a complication of ortho treatment, except in what case?
- tooth movement in the presence of active periodontal disease
- however, once the periodontal disease is under control, these teeth can be moved and can have a good bony response
with respect to alveolar bone, in the absence of pathologic factors, what happens when a tooth erupts to much?
- the tooth carries the bone with it
- the tooth does not erupt out of the bone
- when a tooth is intruded, it doesn’t move into the bone
when teeth are intruded or extruded, the alveolar bone moves with the tooth, thus maintaining the distance between the alveolar crest and the ___
- CEJ
- in other words, the patients biologic width stays about the same when the tooth is intruded or extruded
T or F:
intruding a tooth will create new attachment
false; there is little evidence to support this theory
T or F:
unless a tooth erupts into an area of the dental arch, the alveolar bone will not form there
- true (“no teeth, no alveolar bone”)
- this is seen when a patient is congenitally missing a tooth
what happens to the alveolar bone when a patient has all their teeth extracted for dentures?
- alveolar bone appears to be dependent upon the presence of the teeth
- dentures must be relined every few years as the alveolar bone resorbs
___ functions as the teeth’s supporting structure
alveolar bone
what happens to the PDL space during orthodontic tooth movement?
it widens
during orthodontic tooth movement, the combination of a wider ligament space and a somewhat disorganized ligament means that some increase in ___ will be observed in every patient
mobility
the heavier the force, the greater the ___ and the greater the ___ that will develop
- undermining resorption
- mobility
excessive mobility could be an indication that excessive forces are being encountered on the tooth. what are two possibilities for the excessive force?
- heavy orthodontic forces
- more likely due to a patient who is clenching or grinding against the opposing tooth, causing traumatic interference
- once the traumatic occlusion is corrected and the forces have dissipated, excessive mobility will usually correct itself without permanent damage
what type of pain is typical when orthodontic force is placed on a tooth?
mild aching sensation that varies from patient to patient
what can patients use for pain and discomfort that results from orthodontic treatment?
acetaminophen and ibuprofen is usually sufficient
orthodontic pain typically lasts how long?
2-4 days and then goes away until the orthodontic appliance is reactivated, or for some patients the pain can cycle throughout the month