Orthodontics Flashcards
1-99 L1: examine ortho patient 100-120: Patient History Taking 121-127: Extra Oral Assessment 143-164: Canines 165-202: Cephalometrics 203-223: IOTN
The relative position of the maxilla and mandible, termed the skeletal pattern, has a large influence on the relationship of the maxillary and mandibular dentition. The skeletal pattern should be assessed in three dimensions:
- Anteroposterior
- Vertical
- Transverse (asymmetry)
What is the aim of recording the anteroposterior dimension?
The aim is to relate the AP position of the mandible to the maxilla and the relationship of these bones to the cranial base
Assessment of the position of each jaw relative to the cranial base gives an indication of which jaw may be contributing to a?
malocclusion
An assessment of the severity of the anteroposterior dimension discrepancy will help to guide whether treatment can be provided with?
orthodontics alone or if a combination approach that also involves orthognathic surgery
Why is it important to assess the patient in the natural head position?
It is important to assess the patient in the natural head position, which is a standardised reproducible head orientation, as the tilt of the head can greatly influence the interpretation of the skeletal pattern.
To achieve this, the patient should be sitting upright, relaxed, and looking straight ahead at a distant point at eye level and the teeth should be lightly in occlusion.
The most anterior part of the maxilla and the mandible can be palpated in the midline through the base of the lips. The relationship of the mandible relative to the maxilla can be classified as.
- Class I – when the mandible lies 2–3 mm posterior to the maxilla. The profile is straight.
- Class II – when the mandible is retrusive relative to the maxilla. The profile is convex. The discrepancy should also be classified as mild, moderate or severe.
- Class III – when the maxilla is retrusive relative to the mandible. The profile is concave. The discrepancy should also be classified as mild, moderate or severe.
Image a,b,c indicate what type of anteroposterior classification?
A = class 1
B = class 2
C = class 3
To determine the position of the mandible and maxilla relative to the cranial base, one imagines a vertical line drawn through soft tissue nasion in the natural head position. This line is termed the?
zero meridian 1,2 and represents the anterior limit of the cranial base.
What is the soft tissue nasion?
is the midpoint on the soft tissue contour of the base of the nasal root at the level of the frontonasal suture (marked as N)
The anterior limit of the base of the upper lip (soft tissue A-point) should lie how many mm ahead and the base of the lower lip?
2-3 mm
When making this assessment (anteroposterior relationship), it is important to remember that ethnic variation exits in normal lower face protrusion. The face progressively becomes less protrusive as follows:
African Caribbean > Asian > whites of northern European ancestry.
The term used when both jaws are protrusive is bimaxillary protrusion, which is a common feature in which ethnicity?
African Caribbeans
The vertical skeletal dimension can influence the degree of vertical incisor overlap, lip competency and overall facial aesthetics. There are two methods in which the vertical dimension should be assessed:
- Lower anterior face height (LAFH) proportion
- Frankfort-mandibular planes (FMPA)
Vertically in the frontal view, the face can be split into thirds. What are they?
- Lower anterior face height (LAFH) also known as the Menton
- Middle face height also known as Glabella (should be approx. equal to the LAFH)
- Trichion
The FMPA is assessed in the profile view and gives an indication of the relationship between the LAFH and?
Posterior face height (ramus height)
The Frankfort horizontal plane is measured from where?
The plane connects the lowest point of the orbit and the tragus.
Where is the mandibular plane?
Is the plane that starts at the menton to the angle of mandible
The FMPA is assessed in the profile view and gives an indication of the relationship between the LAFH and posterior face height (i.e. ramus height). It is normal when the line of the mandibular plane and Frankfort plane intersect in the?
occipital region.
If the point intersection (Frankfort plane and mandibular plane) is anterior to the occiput, the vertical dimension Is usually?
Increased
If the point intersection (Frankfort plane and mandibular plane) is posterior to the occiput, the vertical dimension Is usually?
Decreased
What is occiput?
The back of the head
The two components of the transverse dimension that should be assessed are:
- Facial symmetry
- Arch width
It is quite common to find asymmetries in the face, but those that affect the mandible and maxilla are particularly important when planning orthodontic treatment.
The symmetry of facial structures can be assessed by constructing the facial midline between soft tissue nasion and the middle part of the upper lip at the vermillion border. Which other point should be coincident with this line?
The chin point should be coincident with this line
The relative width of the upper and lower arches affects the transverse relationship of the?
Teeth
Which of the dental arches should be slightly wider that the other?
The maxilla
What is a cross bite?
A crossbite is a type of malocclusion, or misalignment of teeth, where upper teeth fit inside of lower teeth. This misalignment can affect a single tooth or groups of teeth, involving the front teeth, back teeth or both.
What are the 5 main types of cross bites?
- Anterior crossbite
- Posterior crossbite
- Single tooth crossbite
- Unilateral crossbite
- Bilateral crossbite
What is anterior crossbite?
In this condition, one or more upper front teeth are positioned behind the lower front teeth, according to the American Association of Orthodontists. This condition is distinct from an underbite, in which all of the top teeth or jaw are positioned behind the bottom teeth.
What is a posterior crossbite?
In a normal bite, the upper back teeth sit slightly outside of lower back teeth. However, in a posterior crossbite, it’s the opposite—the upper back teeth sit inside the lower back teeth
What is a bilateral crossbite?
A bilateral crossbite affects the back teeth of both sides of your jaws. In this condition, the top back teeth are situated inside of the bottom back teeth
What is the most common reason for a bilateral crossbite?
Often result of the upper jaw being underdeveloped
What is unilateral posterior crossbite?
A unilateral crossbite involves misalignment on only one side of your mouth. A unilateral posterior crossbite is where only one side of the mouth has the top back teeth sitting inside the bottom back teeth
The maxilla and mandible are represented by which landmarks when using the zero-meridian line?
The maxilla is represented by the upper lip and the mandible by the chin point.
If the chin or lip is ahead of the zero-meridian line or a combination of both, what would be the skeletal pattern classification of the patient?
Class 3 prognathic
If the chin or lip is behind of the zero-meridian line or a combination of both, what would be the skeletal pattern classification of the patient?
Class 2 retrognathic
What type curvatures would you expect to find in the following skeletal patterns:
1. Class 1
2. Class 2
3. Class 3
- Class 1 – straight curvature
- Class 2 – convex curvature
- Class 3 – concave curvature
For what purpose would do a bi-digital palpation?
Do determine the skeletal pattern
Where is point A and B when you go for a bi-digital palpation?
Point A sits at the deepest curvature between the sub nasal and the upper lips. Point B sits at the deepest part between your lower lip and chin.
How can soft tissues affect the classification of skeletal pattern when you do a extraoral bi-digital palpation?
Different patients have different level of thickness of soft tissue, which could camouflage the underlying skeletal pattern, thus it might be better to do the bi-digital palpation intra-orally.
When doing a bi-digital palpation what would the following results indicate?
- Straight arm
- Arm moves down
- Arm moves up
- Straight arm – class 1 skeletal patten
- Arm moves down – class 2 skeletal pattern
- Arm moves up – class 3 skeletal pattern
How would you position yourself to assess the vertical skeletal pattern on a patient?
In front of them
What is the name of the point on your forehead (prominence between your eyebrows), also used to place the zero-meridian line?
Glabella
What is the name of the point on your chin button?
Menton
What is the name of the point just under the nose?
Subnasle
What position does the head start and end?
Starts at the hairline and ends at the menton
The face can be divided in to how many sections?
3
1- Upper 1/3rd
2- Middle 1/3rd
3- Lower 1/3rd
Where does the upper 1/3rd start and end?
Starts at the hairline and ends at the glabella
Where does the middle 1/3rd start and end?
Starts at the glabella and ends at the subnasle
Where does the lower 1/3rd start and end?
Starts at subnasle and ends at the menton
What is the desired measurement for the 3 sections of the face?
All 1/3rd sections to be equal
The LFH measurement can vary depending on what?
Different position of teeth and jaw
The Lower face Height can be further divided into upper 1/3rd and lower 1/3rd. what are the landmarks for this further division?
1- LFH – upper 1/3rd = subnasle to upper lip
2- LFH – lower 2/3rd = upper lip to menton
What does FMPA stand for
= Frankfort Mandibular Plane Angle
what is the average FMPA angle meant to be?
25 degrees
If the Mandibular Plane and the Frankfort plane are almost parallel and have a low FMPA angle, what does it mean in reference to the intersection point for the FMPA and the growth of the mandible.
1- The intersection of the FMPA will pass the occiput
2- The low angle indicates horizontal growth of the mandible, with low/no vertical growth
The transverse skeletal pattern can be assessed using lines known as?
Facial fifths marking the canthus of the eye and ears.
the landmark where the eye lids meet is known as the?
canthus of the eye
In a well-proportioned face what would you expect the facial fifths measurements to be?
Equal
Assessment of the lip in relation to the teeth is done at two points:
lips at rest and lips whilst smiling
During rest of the lips what two things should you see?
Lips should touch each other or at most should show 1-2 upper teeth.
During rest if the lips are touching each other or maximum two teeth are showing we would refer to this as?
Competent lip
If the lips are apart during rest and is showing more than 4mm of teeth, what would we refer to this as?
Incompetent lip
What are the most common reasons for an incompetent lip?
Proclined or protruded front teeth
On smile for males how much of the incisors would you expect to see?
Full length of the incisor
On smile for females how much of the incisors would you expect to see?
Full length of the incisors plus 1-2mm of the gingiva is considered a youth full smile
Sometime in females, there is an increased exposure of the gingiva known as gummy smile, what is the common reason for this?
Increase vertical growth of the maxilla or short length of the upper lip
What is the condition of oral hygiene before starting any orthodontic treatment?
Immaculate oral hygiene
The extraction of healthy teeth is common during orthodontic treatment, what are the most common healthy teeth to be extracted and why?
The premolars are the most common tooth to be extracted to create space
It is common to see patients with mix dentition, so it is important to be able to differentiate between primary and secondary tooth. What can you do to help aid in deciding if it is primary or secondary?
- If the tooths presence co-relates with the patient’s age
- Check to see if it is firm or mobile
From what age onwards is it important to assess the position of the maxillary canines?
10 years onwards. Should be palpable above the deciduous canines
If you cannot palpate the maxillary canines at age 10 years what would, you do to locate them?
Take an x-ray to locate their position
For the orthodontic assessment of the lower labial segment includes which teeth?
3-3
What is the inclination of the incisors?
The crown inclination, representing an angle formed by the clinical crown axis and a line which bears 90 degrees to the occlusal plane, reflects the labiolingual or buccolingual inclination of the long axis of the crown
hat are the 4 things that are assessed for the lower labial segment? Inclination/aligned/crowded/spaced
Inclination/aligned/crowded/spaced
How would you describe this image?
Bi-maxillary proclination
how would you describe this imagine in reference to inclination?
Average inclination
how would you describe this imagine in reference to inclination?
Proclined incisor inclination
how would you describe this imagine in reference to inclination?
Retroclined incisor inclination
What are the severity parameters for crowding?
- 0-4 mm – mild
- 4-8 mm – moderate
- > 8 mm – severe
What type of analysis is required when the primary molars and canines are still present?
Mix dentition analysis
What is the desired space required for the maxilla and mandible for the eruption of the molars and premolars?
21mm both side maxilla and 22mm both side for the mandible.
When the mesio-buccal cusp U6 sits on the buccal groove L6 what classification is it?
Class 1
When the mesio-buccal cusp U6 sits on the disto-buccal cusp L6 what classification is it?
Class 3
When the disto-buccal cusp U6 sits on the buccal groove L6 what classification is it?
Class 2
What is the reference point to determine the incisor classification?
The cingulum of the upper central incisor, the positioning of the central incisor ahead of the lower incisor
What are the following classifications for these
- Class 3
- Class 2/2
- Class 2/1
- Class 1
In terms of canines, which canine is wider, upper or lower?
Upper
Which canine sits behind the other in canine relationship
the upper always sits behind the lower in a normal canine relationship (class 1)
What is the classification when the mesial slope of the upper canine overlaps the lower canines distal slope?
Class 1