Orthodontics Flashcards
Abbreviations: AFA
Adjust Fixed Appliance
Abbreviations: URA
Upper Removable Applicance
Abbreviations: VFR
Vacuum formed retainer
Abbreviations NiTi
Nickel Titanium
Abbreviations SS
Stainless steel
Abbreviation PC
Powerchain
Three points you assess vertical dimension for
Glabella, subnasale, soft tissue chin
Mandible growth is assessed by two planes (which combined create an angle)
Frankfort plane and Mandibular plane
= Frankfort Mandibular plane angle
FMPA: average, increased, or reduced?
Average = occiput
Increased = ear
Reduced = beyond back of head
Kettle’s method
Kettle’s method assessment for AP relationship. o Index finger and middle finger and palpate upper and lower maximum concavities intra-orally.
Orthognathic vs Prognathic
Prognathism describes when part or all of the face sticks out more than normal. Humans have orthognathic faces. That means the faces is more or less vertical. Most other primates have prognathic faces: their jaws stick out in front of the top part of the head.
Antero-posterior dimension —> class I
Maxilla and mandible orthognathic
Antero-posterior dimension —> class II
Maxilla forward or mandible back or combination
Antero-posterior dimension —> class III
Maxilla back or mandible forward or combination
Do orthodontics help with TMJ?
Could potentially help with crossbites with displacement (however limited evidence)
Lip trap issues
Unaesthetic
Increase in overjet
Risk of trauma
Incompetent lips causes
Proclined uppers
Short upper lip
Nasiolabial angle; what is normal? how is this decreased? how is this increased?
90-110
Decreased by - proclined upper, protruded maxilla
Increased by - retruded maxilla, retroclined incisors
mixed dentition space analysis: average space 2-6? (in mm)
upper -> 22mm
lower -> 21mm
Incisor inclination
Proclined
Incisor inclination
Retroclined
Crowding severity: mild
0-4mm
crowding severity: moderate
4-8mm
crowding severity: severe
8>mm
incisor classification
Class II div I
incisor classification
Class II div 2
incisor classification
class III
What is this showing?
Overjet (horizontal overlap of the teeth)
What is this showing?
Overbite (vertical overlap - the distance between the upper front teeth covering over the lower front teeth)
Canine relationship?
Class I
Canine relationship?
Class II 1/2 unit
Canine relationship?
Class II full unit
Canine relationship
Class III
What is crossbite?
Crossbite is a discrepancy in the buccolingual relationship of the upper and lower teeth.
Location (anterior or posterior)
Nature (buccal or lingual)
When do upper canines erupt?
11-12 years
When do lower canines erupt?
10-11 years old
Interceptive treatment for impacted 3s: success rate of the 3 moving into the correct position after extraction of Cs when the canine covers less than half of the lateral incisor?
90% success
Interceptive treatment for impacted 3s: success rate of the 3 moving into the correct position after extraction of Cs when the canine covers over half of the lateral incisor?
60% success
What principle is used to determine the position of an unerupted tooth relative to its neighbour?
Parallax
What does the parallax principle mean?
Two x-rays are used to locate the position of a tooth. The object furthest away from the x-ray beam will appear to move in the same direction as the tube shift. SLOB (same lingual, opposite buccal)
Horizontal parallax vs vertical parallax?
Horizontal - two periapicals used
Vertical - OPT and upper anterior occlusal
When would you consider taking a lateral ceph?
For patients with skeletal discrepancies (i.e class II or III antero-posterior)
1 - S (sella)
2 - N (nasion)
3 - Or (orbitale)
1 - PNS (posterior nasal spine)
2 - ANS (anterior nasal spine)
3 - point A (subspinale)
4 - point B (supramentale)
1 - Pogonion
2 - Gnathion
3 - Menton
4 - Gonion
What is this angle?
SNA angle ( S —> N —> A)
typically ~81+- 3
What does it mean if the SNA angle is increased or decreased?
An increased SNA angle means the maxilla is more forward than normal, while a decreased SNA angle means the maxilla is more backward than normal
SNB angle (S—> N —> B)
78+-3
What does it mean if the SNB angle is increased or decreased?
An increased SNB angle means the mandible is positioned more forward relative to the cranial base, while a decreased SNB angle means the mandible is positioned more backward
ANB angle
(A—> N —> B)
3+-2
What does an increased ANB indicate?
Can indicate a class II skeletal pattern
What does an decreased ANB indicate?
class III skeletal pattern
Maxillary-mandibular plane angle (MMPA)
27+-4
Maxillary-mandibular plane angle (MMPA) increased vs decreased?
Similar to FMPA —>
Upper incisor - maxillary plane angle
109-+6
Upper incisor - maxillary plane angle decreased or increased?
Skeletal discrepancies (maxilla angulation)
Upper incisal angulation (proclined/retroclined)
IMPA = incisor-mandibular plane angle
93+-6
Lower incisor-mandibular plane angle increased or decreased?
An increased incisor mandibular plane angle (IMPA) means the mandibular incisors are proclined, while a decreased IMPA means they are retroclined.
What is the facial proportion?
~55+-2%
What information can you gather from a cephalometric x-ray?
Antero-posterior and vertical dimensions
What is the Nasion?
What is the Sella?
What does IOTN stand for?
Index of Orthodontic Treatment Need
What are the two components of IOTN?
Aesthetic Component (AC) and the Dental Health Component (DHC)
IOTN: The Aesthetic Component
1-10 grading allocated for attractiveness
Dental Health Component
1-5 Grading based on traits of malocclusion.
IOTN: DHC —> Grade 1-2
No or little need for treatment
IOTN: DHC —> Grade 3
Borderline need
IOTN: DHC —> Grade 4-5
Need treatment
What does MOCDO stand for?
M - missing
O - overjet
C - crossbite
D - displacement of contact point
O - overbite
Yellow portion?
Displacements of tooth contact points and anterior open bites are assessed using the vertical bars.
Red?
This portion assesses any reverse overjet. The first section assesses reverse overjets between 0-1mm. ms -5 refers to reverse overjets >3.5mm with masticatory or speed difficulties.
green section?
This portion assesses increased overjets. 0 section assesses overjets up to 3.5mm which do not score on the DHC. 2c section refers to an overjet between 3.5 and 6mm with competent lips. Section 3i refers to an overjet between 3.5-6mm with incompetent lips. Section 4 assesses overjets between 6.5 and 9mm. Section 5 is for overjets greater than 9mm.
blue section?
All other categories are assess from the middle section of the ruler.
How is hypodontia coded in IOTN guidelines?
5h or 4h
one tooth missing in one quadrant = 4h
two teeth missing in one quadrant = 5h
How is retained deciduous canine/impaction/impeded eruption denoted?
5i
How is an increased overjet denoted?
5a/4a
“a” for bitten into an apple and teeth have proclined horizontally.
IOTN; 5a
increased overjet >9mm
IOTN: 4a
> 6mm but <9mm
IOTN: 5m
Reverse overjet
>3.5mm
WITH masticatory and speech difficulties
IOTN: 4c
Anterior crossbite
OR
unilateral buccal crossbite with mandibular displacement
>2mm
IOTN: 4L
Scissor bite in one or both buccal segments
(scissor meaning the teeth don’t really interdigitate they “scissor” beside each other)
IOTN: 4d
Contact point displacement >4mm
IOTN: 3d
2-4mm contact point displacement
IOTN: 2d
> 1mm but <_2mm contact point displacement
Contact point displacement due to rotations
not generally recorded - would moire be contact point displacements as seen in the image.
IOTN: 4f
traumatic overbite
four-king “forking” = stabbing bite
IOTN: 3f
Deep and complete overbite
“F(th)ree my lower teeth!! they’re hidden”
IOTN: 4e, 3e, or 2e
Anterior open bite/lateral open bite (number depending on size)
> 4mm = 4
IOTN: 5p
Cleft lip and/or palate
IOTN: 5s
Submerging deciduous molar
What can GDPs access to help them grade IOTN and thus refer on?
IOTN advice available on internet/local Orthodontic Managed Clinical Network (MCN).
What scores of DHC and AC are priority?
DHC scores > 4
AC scores > 6
NHS not funding cases with IOTN grades <3.6
IOTN; 4b
Reverse overjet >3.5mm with no masticatory or speech difficulties