Lecture 14 Flashcards
what are 6 things we can control in orthodontics?
- diagnosis -treatment plan
- selection of orthodontic appliances
- brackets, wires, bands
- placement of orthodontic appliances
- forces on teeth
what are a bunch of things we cannot control, or have limited control over, in orthodontics?
patient compliance, growth, tooth size and form, root resorption, ankylosis, impacted teeth, abnormal tooth eruption, bone loss, gingival recession, periodontal disease, temporomandibular joint disorders, muscle/oral habits (tongue, thumb), post treatment tooth movement
what is involved in the questionnaire/consultation appointment?
- chief concern
- medical history
- dental history
- habits
what is involved in the clinical evaluation appointment?
oral health (dental, periodontal, caries, recession, bone loss), TMJ evaluation (max opening, lateral range, CR/CO), facial and dental appearance, pathology, radiographic examination (pano - missing, supernumerary, impacted), molar and canine relationship, transverse and anterior posterior relationships, dentally and skeletally, crowding, spacing, overjet, overbite, curve of spee and wilson, midlines, profile, chin deviation, developmental age compared to dental age, growth disharmony, lip position, primary teeth eruption, tooth size/shape
when evaluating medical history, along with regular dental health evaluations, there are also drugs that can interfere with orthodontic treatment. describe this.
some drugs can stimulate tooth movement (these are unlikely to be encountered, although efforts to produce them continue), direct injection of prostaglandin into the PDL has been shown to increase the rate of tooth movement, but this is quite painful (similar to a bee sting)
which two types of drugs are known to depress the patient’s orthodontic response and may influence treatment?
- prostaglandin inhibitors - pain control
- bisphosphonates - used in the treatment of osteoporosis
osteoporosis is commonly seen in postmenopausal women but can be associated with either males or females. bisphosphonates bind to ___ in bone and act as specific inhibitors of ___.
- hydroxyapatite
- osteoclast-mediated bone resorption
T or F: bisphosphonates are incorporated into the structure of the bone and are quickly eliminated
- false
- while it is true that bisphosphonates are incorporated into the structure of bone, they are actually slowly eliminated over a period of years, so merely stopping the drug does not eliminate all of its effects
most of the bisphosphonate drug is absorbed on the surface of the bone, which makes orthodontic treatment possible after ___ months if bisphosphonate therapy is discontinued
3 months
___ are very important in the inflammatory response, and are formed from arachidonic acid, which in turn is derived from ___
- prostaglandins
- phospholipids
___ reduce prostaglandin synthesis by inhibiting the formation of arachidonic acid
corticosteroids
what are 2 examples of corticosteroids?
- prednisone
- dexamethasone
NSAIDs are prostaglandin inhibitors that work on a chemical level by blocking ___ and ___ enzymes, which play an important role in making prostaglandins
COX-1 and COX-2
___ is a potent NSAID that is used in the treatment of arthritis and can decrease orthodontic tooth movement
indomethacin
what type of NSAIDs typically don’t effect orthodontic treatment?
- over the counter NSAIDs like aspirin, ibuprofen, and aleve, which are short acting
- these are not a problem if they are being use to control acute pain
- however, if an adult or child is being treated for arthritis and is chronically taking over the counter NSAIDs, then this medication could become a problem
what other drugs can affect prostaglandin levels and effect the response to orthodontic force?
- tri-cyclic antidepressants (doxepin, imipramine)
- antiarrhythic agents (procaine)
- antimalarial drugs (quinine)
- anticonvulsant (phenytoin/dilantin)
what should the consultation outcome include?
- informed consent to possible treatment plan options
- the doctor’s role at that point is to determine the treatment plan details, considering effectiveness and efficiency of the various methods to achieve the desired outcome
during orthodontic treatment planning, what should the cast analysis include?
symmetry, spacing, crowding, tooth size, and occlusal relationships
orthodontic casts have traditionally been trimmed with symmetric bases, where the backs are trimmed perpendicular to the midsagittal line. what does this allow?
it allows the models, so that when they are placed on their backs, the models can be picked up in maximum intercuspation
T or F: when trimming orthodontic casts, precise angulation is more important than symmetry
- false
- symmetry is more important than precise angulation
what are virtual dental casts?
- they are produced from laser scans of impressions
- accurate measurements can be done on a virtual dental cast
when examining orthodontic models, what measurements are evaluated?
- occlusal relationship (class I, II, III molar and canine relationships)
- tooth size, shape, and morphology
- overjet, overbite, and open bite (mm measurements describing the severity of each individual problem)
if the incisors flare forward, they occupy an arc of a larger circle, which provides more space to accommodate the teeth and alleviate ___. conversely, if the incisors move lingually, there is less space and ___ becomes worse
- crowding
- crowding
crowding and protrusion of incisors must be considered two aspects of the same thing: how crowded and irregular the incisors are reflects both ___ and ___
how much room is available and where the incisors are positioned relative to supporting bone
space analysis requires a comparison between ___ and ___
the amount of space available for the alignment of the teeth, and the amount of space required to align them properly in the dental arches
what are three ways space analysis can be done?
- directly on the dental casts
- by a computer algorithm after appropriate digitization of the arch and tooth dimensions by scanning the casts
- or intraorally
when doing a space analysis, what is the first step?
- calculation of the space available
- this is accomplished by measuring arch perimeter from the mesial of one first molar to the mesial of the other over the buccal cusps and incisal edges
- this can be done by dividing the dental arch into segments that can be measured as straight line approximations of each arch
- another method can be used by contouring a piece of wire or curved line on a computer image to the arch, then measuring the length of the wire or have the computer compute the length of the line
what is the second step of the space analysis?
- calculate the amount of space required
- measure the MD width of each erupted tooth from contact point to contact point and estimate the widths of the size of the unerupted teeth
- available space minus space required is used to determine the amount of crowding or spacing
in order for space analysis to be correct, what are 3 assumptions?
- the AP position of the incisors in correct
- the space available will not change because of growth and dental compensatory tipping
- all the teeth are present and are reasonably normal in size
- *none of these assumptions can be taken for granted, and all of them must be kept in mind when space analysis is performed
___ is critical to space analysis and information about incisor position must be available from the clinical exam or cephalometric analysis prior to performing space analysis
dental incisor position
the assumption that space is available will not change during growth is valid for most, but not all, children. describe this.
- in a child with a well-proportioned face, there is little or not tendency for the dentition to be displaced relative to the jaw during growth
- teeth often shift anteriorly or posteriorly in a child with a jaw discrepancy, for this reason space analysis is less accurate and less useful for children with skeletal problems
how can unerupted teeth be predicted during a mixed dentition analysis?
- moyers analysis: measure mandibular incisors and then refer to a chart for prediction values
- tanaka and johnston prediction values
the bolton analysis is a cast analysis that was designed following observation that ___ was important to ideal occlusion
tooth size
in the bolton analysis, in order to obtain the proper interdigitation and arch coordination when the molars are in a class I relationship, the ___ has to be proportional to the ___
dimension of the lower teeth has to be proportional to the dimension of the upper teeth (for a patient to have a normal overbite and overjet, the lower teeth must occupy a dental arch that is smaller than the upper arch)
bolton calculated that a ___ between the upper and lower dentition was present when the occlusion was perfect
constant proportion
bolton determined that the sum of the MD dimension of the lower teeth must be equal to ___% the sum of the MD dimension of the upper teeth
91%
bolton also discovered that a satisfactory class I canine occlusion was only possible if a ___ was present between the upper and lower anterior teeth
specific proportion
the sum of the size of the MD dimension of the lower anteriors must be ___% of the sum of the size of the MD dimension of the upper anterior teeth
77%
the bolton analysis is now mainly used for ___
anterior region
what 3 things does photographic analysis examine?
- profile type (concave, convex, orthognathic)
- facial symmetry (chin, eyes, nose, cheeks)
- lip position (protrusion, retrusion)
vertical facial proportions in the frontal and lateral views are best evaluated in the context of ___, which are typically equal in height in well-proportioned faces
facial thirds
in modern caucasians, the ___ facial third is often slightly longer than the ___ third
- lower
- central
which facial third is further divided into its own thirds, and what are they?
- lower third
- the corners of the mouth should be 1/3 the way between the base of the nose and chin
- the chin and lower lip should occupy 2/3 of the lower third
in the frontal plane, an ideally proportioned face can be divided into ___, ___, and ___ equal fifths
central, medial, and lateral
describe how the frontal plane is divided into fifths
- the separation of the eyes and the width of the eyes, which should be equal, determine the central and medial fifths
- the lateral fifths are from the outside corner of the eye to the edge of the face
- the nose and chin should be centered within the central fifth, with the width of the nose the same as, or slightly wider than, the central fifth
- the interpupillary distance should equal the width of the mouth
everyone typically has some ___ in their facial appearance
asymmetry
the degree of asymmetry determines if the asymmetry is within normal ranges. typically, the asymmetry is considered abnormal if it is ___
noticeable to the general public or patient
___ are the best way to illustrate normal facial asymmetry
- composite photographs
- this technique dramatically illustrates the difference in the two sides of a normal face
usually, the ___ side of the face is a littler larger than the ___ side
right side is a little larger than the left side
profile convexity or concavity results from a ___, but does not by itself indicate which jaw is at fault
disproportion in the size of the jaws
a ___ facial profile indicates a class II jaw relationship, which can result from either a maxilla that projects too far forward or a mandible too far back
convex
a ___ facial profile indicates a class III relationship, which can result from either a maxilla that is too far back or a mandible that protrudes forward
concave
ENT doctors referral and allergists are often needed for what patients?
dolicocephalic, adnoid facies, long face syndrome
what is the clinical presentation of brachiocephalic patients?
- low mandibular plane angle
- short anterior face height
- deep bite
- patients typically follow a class III growth pattern with low horizontal mandibular growth
bimaxillary dentoalveolar protrusion is seen in the facial appearance in what 3 ways?
- excessive separation of the lips at rest (lip incompetence)
- excessive effort to bring the lips into closure (lip strain and mentalis activity)
- prominence of lips in the profile view
- *remember that all 3 soft tissue characteristics must be present to make the diagnosis bimaxillary dentoalveolar dental protrusion
the general guideline for lip separation at rest should be no more than ___mm, which holds for all racial groups
4mm
the guideline for lip separation at rest holds for all racial groups because different racial groups and individuals within those groups generally have the same degrees of lip prominence that are independent of tooth position
- false
- different racial groups and individuals within those groups have the different degrees of lip prominence that are independent of tooth position
because different racial groups and individuals within those groups have different degrees of lip prominence, excessive dental protrusion must be a ___ diagnosis
- clinical diagnosis
- it cannot be made accurately from cephalometric radiographs