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Terms in this set (171)
What are the steps of the first visit to the orthodontist/dentist?
Initial exam and inteview
What should be included in the initial exam of an ortho consult?
Med, dent and family history
What three points are compared to determine the facial profile from the side?
Glabella, subnasal, pogonion
What is the E line?
A line that extends from the top of the nose to the pogonion of the soft tissue. It is used to evaluate the anterior-posterior position of the lips. If the lips lie in front of this line the lips are protrusive
What sort of bite might someone with a steep mandibular angle have?
What are you looking at on an ortho IO exam?
Angle classification of malocclusion
Explain what a class 1 molar relationship is.
MB cusp of upper 6 should rest on MB groove of lower 6
Explain what a class 2 molar relationship is.
Lower molar positioned at least half a cusp distal to class 1 position
Explain what a class 3 molar relationship is.
Lower molar positioned at least half a cusp mesial to class 1 position
What are the division of class 2 molar relationship?
Div 1 - maxillary anteriors proclined with a large overjet
Div 2 - maxillary anteriors retroclined with a deep overbite and vampire fangs.
What is a normal overbite?
What is a normal overjet?
What is the primary treatment goal of the Angle and soft tissue paradigms?
Angle- achieve ideal occlusion
Soft tissue- achieve normal soft tissue proportions
What are the 4 steps of orthodontic triage?
1. Identify any syndromes and developmental abnormalities (cleft lip, Treacher-Collins' syndrome)
2. Identify facial profile problems
3. Identify dental development problems
4. Identify space problems
If you extract a primary tooth or it is missing for any reason what must be done after this?
Must place a space maintainer to prevent drift of teeth otherwise space will be lost
What tooth does not require a space maintainer if it is lost?
What two abnormalities may result from thumb sucking?
Narrowing of maxillary arch from suction
What is a scissor bite?
When the palatal surface of the maxillary molars is lateral to the buccal surface of the mandibular molars. ie their occlusal surfaces dont touch and the teeth pass by each other close to one another like scissor blades.
When is orthodontic extraction indicated?
When there is a deficit of 10mm or more in arch space from that required.
What is orthodontic camouflage used for?
Moving the teeth to hide a skeletal problem. Eg removing maxillary PMs and pulling maxillary anteriors posterior to camouflage mandibular deficiency.
What three options can you use to correct mandibular deficiency?
1. Enhance anterior growth of the mandible in preadolescent years
3. Mandibular advancement surgery
What appliances may be used to correct mandibular retrognathia/maxillary prognathia?
Twin block (patient must move mandible forward or blocks get in the way of closing the jaws)
Herbst appliance (metal bar hinge forces mandible forward)
Cats whiskers headgear (slows maxillary growth to allow mandible to catch up)
A sagittal analysis will help identify what?
Anterior-posterior discrepancies. ie molar relationship, skeletal class
A vertical analysis will help identify what?
High/low angle mandible
A transverse analysis will help identify what?
What appliances may be used to correct skeletal class III discrepancy?
Reverse pull headgear
What part of the mandible ossifies by endochondral ossification? What other cranial structure ossifies like this?
Mandibular condyle. Cranial base also undergoes endochondral ossification.
The cranial vault, the maxilla and the body of the mandible undergo what type of ossification?
At what age is bone growth rapid in males and females (ie the time we wish to take advantage of to modify growth if needed)?
Around 12 in females and 14 in males
At what age does maxillary growth stop in males and females?
15 in girls
17 in boys
At what age does the maxillary symphasis fuse? What implication does this have maxillary expansion?
Fuses in teenage years. Expansion must be performed prior to this.
In what direction does the maxilla grow during puberty?
Down and forward
How does the mandible grow forward during pubertal growth?
By growth at the condylar cartilage. Bone is also laid down on the posterior aspect of the ramus and resorbed at the anterior border allowing for disal elongation of the dental arch.
What stops growing first, the mandible or the maxilla?
At what age does mandibular growth stop in girls and boys?
Stops growing at 17 in girls and 19 in boys
What is the normal direction of facial growth?
Down and forward
What occurs if there is excess forward rotational facial growth?
Reduced vertical dimension and increased overbite.
What occurs if there is a backward rotational facial growth?
Increased vertical dimension, steep angled border of the mandible and a reduced overbite or an open bite.
What is the best indicator of stage of skeletal maturation? What else may be used?
The best predictor is to add average growth increments to the patients existing facial pattern. Radiograph of the hand and wrist is used commonly but the correlation with jaw growth is poor. Cervical vertebral maturation index is also used.
What is a rapid maxillary expansion device used for?
To create space in the maxillary arch. eg to make room for an impacted canine to erupt. Or to expand the maxilla in class III skeletal discrepancy.
What maxillary tooth often has trouble erupting in the maxilla due to being last to erupt?
What mandibular tooth often has trouble erupting in the maxilla due to being last to erupt?
What is normal occlusion in the deciduous dentition? Why does this change in the adult dentition?
Cusp to cusp. This changes to class I molar relationship in adult teeth. This is because the mandibular E is longer mesiodistally than the upper E. When these are lost the lower 6 drifts more mesially than the upper 6.
What is decompensation in relation to corrective class III treatment?
It involves proclining the retroclined lower incisors and retroclining the proclined upper incisors. This exacerbates the negative overjet (hence decompensation). Orthagnathic surgery then adjusts the mandible to make the teeth line up.
Why is mandibular expansion not ever a treatment option?
Because the mandibular symphysis closes at 1 year of age.
Number of primary teeth?
Number of permanent teeth?
Class I molar relationship
MB cusp of upper 6 sits in the MB groove of lower 6
Class I canine relationship
Upper canine sits in the lower embrasure between 3 and 4
Class II molar relationship (full)
MB cusp sits between lower 5 and 6
Class III molar relationship
MB of upper 6 is between 6 and 7 (fulle
Space between upper and lower incisors in the horizontal plane
Lack of overlap between upper and lower teeth of anterior or posterior teeth
Look up definition of half and full unit class shift
Class I incisor relationship (British)
Lower incisor should occlude on the cingulum plateau of the upper incisor
Class II incisor relationship
Lower incisor occludes on the gingival third of the palatal surface of the upper incisor
Lower incisor occludes on the incisal third of the palatal surface of the upper incisor
How do you confirm a unilateral crossbite?
Get them to put their tongue to the very back of the mouth and get them to slowly close until their teeth make light contact. This is the best way to achieve CR. Look for the width of the maxilla in this position. Look to see if there are just a few teeth in contact in this position that may suggest the mandible undergoes a functional shift to get to CO that camouflages a bilateral.
Why does thumb sucking result in a narrow maxilla?
The tongue drops and doesn't support the maxillary teeth so cheek tongue equilibrium is out.
What else may occur to the teeth in thumb suckers?
The teeth aren't in occlusion so they over-erupt.
What type of maxillary expansion device achieves skeletal movement best?
Bonded rapid maxillary expansion device. Turn it daily and leave it in until it is over corrected so the upper palatal cusps are end on end with the lower buccal cusps. Check every couple of weeks. Minimum time 6-9 months then issue a retainer.
How do twin blocks achieve their result?
Muscles reset to be used to the new position. There is also some remodelling of the condyles. Need to wear it for 12 months. Can only use in the growing patient.
What appliance do you use for maxillary prognathism (class II)?
What appliance do you use for mandibular retrognathism?
What appliance do you use for a class III?
Rapid maxillary expansion and reverse headgear. You can also extract lower PMs or even a single lower incisor to shrink the mandible.
What teeth are extracted for class II malocclusion?
Upper 4s to reduce overjet and lower 5s to achieve class I molar relationship.
What is therapeutic class II?
Extracting the upper 4s and correcting overjet but leaving lower class II relationship.
What is the class III extraction pattern.
Upper 5s lower 4s
What is the skeletal relationship in those with class II div 2 dental relationship in many cases?
Class III. They have a deep bite and the lower lip pushes on the upper central incisors and retroclines them. The lateral erupt later and get proclined by the lip. Looks like Kirsten Dunst.
What is cepha analysis?
Evaluating the skeletal, dental and soft tissue relationships of a patient, by comparing measurements performed on the cephalometric tracing with population norms for the respective measurements, to come to a diagnosis of the patient's orthodontic problem.
What is the treatment for 0-4mm of anterior crowding?
What is the treatment 4-8mm of crowding?
Fixed appliance and braces
What is the treatment when there is greater than 8mm anterior crowding?
What is class II div 2?
Class II dental relationship with retroclined upper incisors and a deep bite.
What is class II div 1?
Class II dental relationship
Following removal of twin blocks what do you need to do?
Put braces on to fix the teeth while occlusion is sorted out?? Then place a retainer.
An appliance that holds your jaw forward. It alters the position of the mandible activating muscle groups. This has the potential to adjust the direction of jaw growth and the eruption of teeth.
What do all functional appliances do?
They hold the mandible forward
What are the options for class II div I
Why do you extract all 4's for creating space?
Using the lower 6s as as anchor to pull the upper 3's back the lower posterior teeth will move forward. If you don't extract the lower 4's the lower incisors will proclinate.
What two groups of growth appliances are available?
Headgear and functional appliances
Why do you trim the acrylic of twin blocks?
To allow eruption of posterior teeth
How do you treat a class II div II?
Convert them to class II div I then use a functional appliance
What are the requirements for a using a functional appliance?
Growth, brachyfacial (high angle don't do as well), mandibular retrusive, retroclined lower incisors
What is roux and wolf's theory?
Bone is plastic and that form is intimately related to function
What are the three theoretical possibilities for growth modification?
An absolute increase or decrease in jaw size
Redirect jaw growth
Accelerate desirable growth (this is the most accurate theory)
How much overjet do we usually need to correct with functional appliances?
Where do we get this 6-7mm of mandibular advancement?
Condylar growth 1-3mm
Fossa growth and adaptation of condylar head 0.5-1mm
Elimination of functional retrusion 0.5-1.5mm
Withholding downward and forward movement of the maxilla 1-2mm
Differential upward and forward eruption of lower buccal segments 1.5-2.5mm
Headgear effect pushing the whole maxilla back 1-2mm
Does the mandible get longer with a functional appliance?
No. It makes growth happen sooner and allowing dental structures to make accommodations for its new position.
Why don't we want to put a clasp on the lower molars for a twin block?
Because we want the lower molars to grow forward into a class I position. Get retention from lower anteriors.
How far forward do you hold the mandible fort he twin block?
About edge to edge
Why do you need to expand the maxilla as part of hue he twin block?
Because as you bring the mandible forward it is occluding with a narrower part of the maxilla so it needs to be expanded to accommodate the mandible.
How do you retain the MMR following use of twin block? What is an alternative to this?
Braces and class II elastics. You can put the braces on at the same time as the twin block. Minimises the time they need to have treatment.
What is the best time to treat with functional appliances?
Treat in the mixed dentition if there is lip incompetence to minimise social trauma. Otherwise treat when in the permanent dentition.
What happens if maxilla and teeth grow more than the growth of the fossa and condyle?
You get a high angle (dolichofacial) open bite
What is the prognosis for using functional appliances in high angle cases?
What are some ways of intruding teeth to correct a high angle case?
High pull headgear
Encroach on freeway space with plastic
Don't trim the acrylic on the twin block
What facial shape are almost all class II div II cases?
What three things does Bass say makes up a desirable facial appearance?
The nasolabial angle should not be obtuse
The chin should be normal
The slop and angle of the upper incisors
What is the reason for relapse of tooth position after ortho treatment?
Rate of tooth movement is rate of bone resorption. Resorption is faster than bone deposition on the other side so teeth tend to move back to their original position unless a retainer is worn.
What are the four components to a removable appliance?
Baseplate - acrylic cover
Retention - baseplate, clasps, bows
Active - springs, screws, bows
Anchorage - palate, extraoral
What are removable appliances useful for?
Simple tipping movements
Moving only a few teeth at a time
Tipping teeth about a fulcrum close to the middle of the root
Where does the centre of resistance move when the object is more dense at one end?
It moves toward the the dense end of the object
Where does the centre of resistance move when the object's environment is more dense at one end?
It moves toward the end of the object that is surrounded by the more dense environment.
Where is the centre of resistance of a single rooted tooth?
About 1/3rd down the root from the apical
What is the relationship between point of force applied in relation to centre of resistance and centre of rotation?
The further from the centre of resistance force is applied the closer the centre of rotation will be (more rotation)
What is the moment of force?
The rotation caused by a force acting at a distance from the centre of resistance. Moment = force X distance from centre of resistance
How do you reduce rotation of a tooth while moving it?
Apply force close to the centre of resistance and use low force. eg labial bow is placed more gingivally and low forces used to reduce rotation of incisors.
What are the disadavanteges of removable appliances?
Difficult to move teeth that are unfavourably inclined (except incisors) and rotated.
Difficult to close spaces and achieve good approximal contacts
Lower appliances poorly tolerated
What is the maximum rate of screw turning for a slow maxillary expansion removable appliance?
1 turn/5 days to achieve about 0.25mm expansion per week or 1mm per month.
OVer expand by 30% to compensate for relapse
How do you tell the difference between a functional shift, a dental midline shift and a skeletal shift?
Functional shift - the midlines line up when patient opens
Dental midline shift - the mandible will be aligned normally but the teeth won't be
Skeletal - the mandible will be off centre in both open and closed postions
Wh do you have to correct functional shifts early?
Because they act like a functional appliance and can give rise to growth abnormalities
What type of orthodontic clasps are used for removable appliances?
Adams clasps for molars
Ball clasps for premolars
What active component is used to procline maxillary incisors?
Piston screws (not clinically effective)
What active component is used to retrocline maxillary incisors?
U loop labial bow
When are twin blocks used?
Skeletal class II malocclusion
When the upper teeth come into intercuspation when moved into class I.
What happens to vertical dimension when the mandible moves forward into class I from class II with twin blocks?
The vertical dimension increases and posterior occlusal contacts are lost. Acrylic must be trimmed to allow eruption of molars to create occlusion and vertical dimension.
What retainers are available?
Hawley - clasps, acrylic baseplate, labial bow
Begg - wrap around labial bow, no wire crosses occlusal surface to allow maximal settling
Trutain - suckdown
How long should retainers be worn following ortho?
6 months day and night followed by 3 months of nights only
What is couple of force?
Two forces that are equal, parallel and in opposite directions. They create pure rotational movement.
What four variables characterise a force?
Point of application
Plane of action
What are the 4 D's of force?
Distribution (of pressure along the root surface)
What are some different type of duration of force used in ortho?
Continuous decreasing - braces
Intermittent - headgear
Continuous and constant - difficult and not really used (Profs. wheel invention)
What factors may change the centre of resistance of a tooth?
Perio, osteoporsis, crown fracture, root resorption
According to Schwartz what is the ideal amount of force for maximum tooth movement without tissue damage?
Between 7-26 g/cm square. Below this teeth wont move and above it necrosis occurs.
What are the two forms of bone resorption in response to ortho?
Direct and indirect
Describe the process of bone resorption in terms of direct and indirect resorption
Initially there is a lot of pressure and this causes indirect resorption of the bone. This is pathological and called hyalinisation. Following this comes direct (ideal) resorption of bone
What are the 5 types of orthodontic tooth movement?
Tipping (mesio-distal around CRot)
What is the name given to pure bodily movement and how is this achieved?
Force must go through the centre of resistance.
What type of tooth movement has the highest rate of relapse?
What are three categories of anchorage?
Maximum (eg headgear)
Minimum (eg space closure)
What type of skeletal anchorage devices are available?
Management of class III malocclusion
What dental options do we have for correction of class III malocclusion?
Exo or non-exo treatment
What skeletal options do we have for correction of class III malocclusion?
What three points need to be considered before considering growth modification for class III correction?
What growth modification techniques can be used to correct class III malocclusion?
Reverse pull headgear
Class III elastics
What is easier to treat, maxillary deficiency or mandibular prognathism?
Maxillary deficiency with maxillary expansion
Mandibular prognathism requires surgery
What is the acronym for ways to create space in a patient with crowding?
What does SPEED L stand for?
S - stripping (can strip 0.5mm per tooth)
P - protrusion
E - extraction
D - distlaisation
L - leeway space
How much space is gained by protruding the upper incisors by 1mm?
How much space is gained when you expand the maxilla by 10mm in the transverse plane?
What devices may be used to distalise molars?
Pendulum fixed appliance
How much leeway space is gained in the upper and lower arches?
This results in mesial drift of lower 6 moving into class I molar relationship
What is leeway space?
The difference in mesiodistal width between C,D,E and 3,4,5
What is a prerequisite for using leeway space to correct crowding?
That molars are in class I relationship. If not the leeway space will need to be used to correct molar relationship.
What questions must you ask youself when you come accross a class III case?
Is it skeletal or dental?
Is it maxillary/mandibular/mixed in origin?
Is there a concurrent vertical or transverse problem?
Is it mild, moderate or extreme in severity?
Is there a hereditary component?
What treatment options are available for correcting dental class III?
Extraction of lower teeth
What treatment options are available for correcting skeletal class III?
What must be considered when determining the severity of a class III case?
Mandibular excess (more severe)
Amount of discrepancy
Age and growth potential (more severe class III when a child as they are usually class II but also has more time for growth modification)
Heredity (more severe)
What growth modification can be performed in a young class III patient (eg 7 years)?
Reverse pull headgear with maxillary expansion followed by class III eleastics. Studies show you get more maxillary protraction when combined with an RME.
If growth modification fails to correct class III what is the next treatment option once patient is fully grown?
Surgery (Le Fort I maxillary protrusion and/or BSSO)
How do you measure a transverse descripancy between maxilla and mandible?
Compare the measurements between the upper MP cusps of the 6s and the central fossa of the lower 6s
How do you expand a small maxilla due to dental deficiency?
Arch wire expansion
How do you expand a skeletally deficient maxilla?
What are some signs of a skeletally deficient maxilla?
normal angulation of posterior teeth
What are some signs of a deficient maxilla due to a dental discrepancy?
Palatally tipped upper posterior teeth
What is the maxillo-mandibular transverse differential index?
The difference between actual and expected maxillo-mandibular width difference as measured on a PA ceph.
When is skeletal expansion recommended with reference to the maxillo-mandibular transverse differential index?
When the maxillo-mandibular deficiency is greater than 5mm from expected values.
When should a transverse maxillary deficiency be treated if it causes a functional shift?
At what age should the maxilla receive orthopaedic expansion?
Less than 15. Highest expansion when placed younger (eg 8 years old)
In children under 12 what proportion of net expansion is due to skeletal expansion? How does this compare to children over 18?
Under 12 50% is due to skeletal expansion
Over 18 only 16% is due to skeletal expansion
Each turn of an RME gives how much expansion?
When must you use banded expansion devices?
When the patient is in the late mixed dentition stage. Otherwise for primary, early mixed or permanent dentition use bonded.
How much must you over correct when performing maxillary expansion?
How long does treatment last using rapid, semi-rapid and slow maxillary expanders?
Rapid - 1-1.5months (one turn per day)
semi-rapid - 4-6 months
Slow - 6-10 months (one turn per week)
What are two types of RME devices?
Hyrax (suitable for late adolescents when growth is slowing)
What is an example of a semi-rapid expansion device?
Quad helix (suitable for rapid growers)
What surgical techniques may be used to correct class II?
Le Fort 1
What surgical techniques may be used to correct class III?
BSSO set back
Le Fort 1 (1,2 or 3 piece)
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