Orthodontics - ABGD Oral Boards Flashcards
Where are the primate spaces?
- Maxillary Primate Space distal to laterals
- Mandibular Primate Space distal to canines
How many mm is Incisor Liability in primary dentition in the maxilla?
7.0 mm
How many mm is Incisor Liability in primary dentition in the mandible?
6.0 mm
How man mm is Transient Mandibular Crowding?
0 - 2.0 mm
What happens to primary teeth as they transition to the permanent dentition?
- Interdental spacing in primary dentition
- Increase in intercanine width (2 mm)
- Slight labial positioning of the incisors (1 - 2 mm)
- Distal shift of canines as primary first molars are lost (md/1mm)
What is Leeway Space?
- Mesial/Distal size difference between the primary molars and canines and permanent premolars and canines
- 1.5 mm maxillary arch per quadrant or 3 mm per arch
- 2.5 mm mandibular arch per quadrant or 5 mm per arch
What accounts for the “E” space?
Most of the space is due to the size difference in the second primary molars
What are the 3 Primary Second Molar relationships?
What are 3 factors that influence the first permanent mlar relationship?
- Early mesial shift
- Late mesial shift
- Differential growth
What types of occlusion will primary distal step, flush terminal plane, and mesial step typically transition into in the permanent dentition?
What does a Flush Terminal Plane Typically transition into?
- Most develop into Class I relationship (75%)
- Not stable and may develop into Class II relationship
What Molar Class is this?
Class I Molar
How do you develop a Class I Molar Relationship?
Early Mesial Shift
- Flush primary second molars
- Space primary dentition (priamte spaces)
- Normal eruption pattern-mandibular first molar migrates mesially to close primate space
How else can you develop a Class I Molar Relationship?
Late Mesial Shift
- Flush primary second molars
- Closed primary dentition (no primary spacing)
- Class I conversion via leeway space
When you have a Mesial Step, what permanent dental occlusion is likely?
Mesial Step
- Class I or Class III
- Dependent upon extent of step seen clinically and patient’s growth pattern
- Refer for early evaluation (by 8 years)
What type of occlusion is this?
Class III
What type of adult occlusion will a Distal Step typically evolve into?
Distal Step
- Usually develops into Class II skeletal and dental malocclusion
- Flush terminal plane plus factors which reduce arch length
- Refer for early evaluation
What’s the difference between Class 2 Div I and Class 2 Div II?
What type of occlusion is this?
Class II Div I
What type of occlusion is this?
Class II Div 2
Which teeth most commonly show Ectopic Eruption?
- Maxillary First Permanent Molars
- Incisor
- Canines
What % of Ectopic Eruptions self correct?
60%
- If not, may continue to resorb primary molar or impact permanent tooth
- Preserve primary second molar if possible
What is going on here?
Ectopic Eruption
How can you treat Ectopic Eruption?
Separators
Describe the Radiographic Method of Space Analysis…
- Requires undistorted periapical radiographs
- Requires Algebra…solve for uknown!!!
- Casts
- Calipers
True width of primary molar/Apparent width of primary molar
=
True width of unerupted premolar/Apparent width of unerupted premolar
What are some space analysis names that have Proportionality Formulas?
Tanak and Johnston
Describe the Tanaka-Johnson Formula…
- No radiographs
- Predicts both arches
- Reasonably good correlation
- Data obatined from Caucasion population, may not be approppriate for all ethnicities
What is a Combination medthod of Space Required Analysis?
Hixon/Oldfather, revised by Staley/Kerber
- Periapical radiographs of premolars and canines
- Proportionality tables
- Highly accurate - but tables developed from Caucasian children of European ancestry
What are 3 key recommendations for Mixed Dentition Space Analysis?
- High-quality periapical radiographs can be difficult to obtain on children
- Tanaka-Johnston formula has good accuracy and is very convenient
- May need to resort to radiographs, however, if patients are not Caucasian
What is the Bolton Tooth Size Analysis?
Evaluation of the mesial/distal tooth size discrepancies between maxillary and mandibular arches
What is the formula for the Bolton Space Analysis?
Describe the Interpretatin of the Bolton Space Analysis…
- Disproportion will be expressed in mm of either…
- Excess
- Deficiency
- It is up to the dentist to determine which it is
- Rule of thumb: “If the canines are Class I, the incisors should fit together”
- Also need to look at overjet
What canine class is this?
- Class I Canines
- Ideal Overjet
- Max Spacing, Small Laterals
What canine classification is this?
- Class II canines
- Ideal overjet
- Laterals width acceptable
What is the most common Bolton discrepancy?
Mandibular Excess
- 2 mm or more will likely rquire Man IPR or Max bonding to finish
- Alluding to lower picture…Now close spaces to acheive ideal OJ and Class I canines
What is the Gold Standard to determine how teeth will fit together following lower incisor extraction?
Kesling Set-up
- Will need to:
- Duplicate casts
- Cut teeth out precisely
- Set in wax
This picture is exemplifying the…
Kesling Set-up
If you have a tooth size discrepancy, treatment decision depends on…
- Canine relationship
- OJ
- Intra-arch tooth size relationships
What is the purpose of Serial Extractions?
“Robbing Peter to pay Paul”
That is, the purpose of serial extractions is to push the crowding from the anterior region to the posterior region
What are some Criteria for Serial Extractions?
- Mixed dentition stage
- Severe dental crowding (> 10 mm)
- Class I skeletal with no other skeletal discrepancies
- Class I molar with normal OB and OJ
How can a Panorex help you in the mixed dentition state?
- Aids in detection of supernumerary and congenitally missing teeth
- Detection of pathologic conditions
- Determination of the size, shape, and relative position of unerupted teeth
- Assessment of primary root resorption and of permanent root formation
What is the Key to Serial Extractions?
- Key: Extract 1st premolars prior to cuspids erupting
- Even if performed perfectly, almost all cases require fixed appliances to finalize the occlusion
What type of Class Serial Extraction is this picture showing?
- Extract primary canines (C’s)
- To allow eruption of the lateral incisors (2’s)
What Classis Serial Extraction Pattern is going on here?
- Extract the primary first molars (D’s)
- When the permanent first premolars (4s) roots are 1/2 to 2/3 formed
What Classic Serial Extraction Pattern is going on here?
- Extract permanent first premolars (4’s)
- To allow the permanent canines (3’s)
- And the second premolars (5’s) to erupt