4B Flashcards
Growth Modification
● Female at
15 is post adolescent (16 for males) - can’t use RPE bc midpalatal suture fused
Treatment options for Skeletal malocclusion ⇒
growth modification, camouflage, & surgical treatment
Sites of facial growth:
● Growth centers ⇒
● Growth sites ⇒
nasal septum; synchondrosis
sutures; condyle; alveolus
Sutures & alveolus have good ——-; synchondrosis have ——-; condyle/nasal septum ——-
modifiability
poor
questionable
Requirements for growth modification:
● Growth patient
● Ability to affect sutures
● Condyles require function (including translation)
● Alveolus require teeth (or a functioning unit)
Periods of rapid growth make modification process easier:
● Males
● Females
12-14 (13-15) y/o
10-12 y/0
Somatic & facial growth ⇒ loosely related
in growth timing
● Growth has variable rates
(fastest from 0-2 years & adolescent growth spurt)
● Noses ⇒
males have more nose growth than females (esp. post-adolescence)
● Lip competence ⇒
increases with age (lips grow vertically more than skeleton)
● Lip protrusion ⇒
decreases with age (lips thin with age)
● Chin ⇒
Males get more chin button than females
● Late growth:
○ Maxilla downward growth & Mandible forward growth post-adolescence
○ Women ⇒ more —— growth; Men ⇒ more ——— growth
maxillary
mandibular
Methods for growth assessment:
● Ht. & wt. Measurements; secondary sex characteristics; menarche (occurs after peak growth spurt)
● Cervical vertebrae & cephalometric XR
US population ⇒ Class II malocclusion ——-; Class III malocclusion =======
15-20%
3-5%
General dentists can diagnose skeletal problems by
profile analysis & assessing dental relationships
● Profile analysis difficult for
young children (esp. <6 y/o), Class III, & when vertical problems present (profile analysis possible, just need to be careful)
● Dental relationships:
○ Provides good clues in
Class II & III malocclusion (esp. when profile agrees)
■ Ie. increased overjet with class II molars & convex profile → likely Class II problem
○ Can be deceptive when habits affect the teeth
■ Ie. anteriors don’t coincide with posteriors in giving info about malocclusion type
Indications for growth modification ⇒
growing patient with mild-moderate skeletal problems
Indications for growth modification
● Severe problems need surgery
Indications for growth modification
Possibilities for growth modification:
● Maxilla →
easier to modify than mandible
Indications for growth modification
Possibilities for growth mod
● Anteroposterior →
possible
Indications for growth modification
Possibilities for growth mod
● Vertical →
hardest to modify; last dimension to stop growing
Indications for growth modification
Possibilities for growth mod
● Transverse →
first dimension to stop growing (why maxillary constrictions need to be treated early)
Types of growth modification:
● Ultimate size changes (stimulation/retardation)
● Timing changes (acceleration/deceleration) - no overall change in size
● Redirection
Classic one phase growth modification with comprehensive orthodontic care
● Ideal to modify growth & provide comprehensive ortho at the same time - one phase treatment
Class II maxillary protrusion ⇒ Treat with
headgear (restricts maxilla & allows for mandibular growth)
● High-pull headgear ⇒
force directed posteriorly & superiorly
● Cervical pull ⇒
force directed posteriorly & down
● Combination headgear ⇒
force directed more horizontal
● Example results of headgear pt:
○ maxilla still grows downward, but NOT forward
○ Mandible grows downward & forward, becomes more prominent
Class II mandibular retrusion:
● Treatment with
functional appliances
○ Brings mandible forward, unloading condyle & allowing mandibular growth
○ Forces push mandible forward & maxilla backward → upper teeth retrude; lowers protrude
● Example of functional appliance pt:
○ Mandible comes forward more than downward
○ Maxilla maintains normal downward growth, but less forward growth
Class III maxillary retrusion
● Treatment with
facemask - reverse pull headgear
○ Can expect——-mm of forward maxilla growth in year
2-3
○ Mandible rotates down & back → patient profile becomes more convex
○ Upper incisor protrusion
Reverse pull headgear
● Only effective in children
< 10-11 y/o - before sutures fuse
Class III mandibular protrusion treatment options:
● Functional appliance
● Chin cup → minimal long term success; rotates mandible down & back, but essentially no change
Maxillary constriction treatment
● Rapid or slow palatal expansion (depending on age)
● Lingual arch type in primary & mixed dentition
● RPE ⇒ for near & post-adolescent
● Lingual arch type in primary & mixed dentition
○ Opens
midpalatal suture in preadolescent
○ Can also correct posterior crossbite (moves teeth)
Skeletal changes can be made in ———–. Skeletal changes tend to go back a little bit during maintenance period
growing children
Is early Class II Tx beneficial ⇒
No
● Restraining maxilla (headgear) or growing mandible (fxnal appliance) is
of NO benefit to ultimate growth if done in early mixed dentition over late mixed dentition
Class II tx ● With early treatment ⇒
get to same point, but requires 2 phases of treatment
Is early class III tx beneficial? ● In true maxillary retrusion ⇒
max. protraction successful if done before 10 y/o
○ ~25% cases still fail; simultaneous expansion questionable
Is early transverse treatment beneficial?
● Appears transverse skeletal & dental changes can be made & maintained
○ These changes can affect unerupted teeth
● As arch dimensions change so does available space
When is early treatment justified: ● For class II ⇒
based on benefits of esthetics or trauma reduction
when is early treatment justified; ● For class III ⇒
True maxillary deficiency
and
● Posterior crossbites
Normal biologic variation (mild crowding/spacing; class II or III) ⇒
orthodontic treatment
Extremes of normal variation (malocclusion of skeletal origin) ⇒
orthodontics & surgery
Dysmorphology (often craniofacial anomaly) ⇒
requires craniofacial team
Dysmorphology
● Etiology →
mostly unknown
Dysmorphology
○ Also
facial syndromes; postnatal growth disturbances; inherited tendencies; environmental
Treatment options for skeletal malocclusion:
● Growth modification
● Camouflage
● Surgical orthodontics ⇒ for severe cares (~5% of malocclusions require surgery)
Surgical options for A-P discrepancy (Class II or III)
● Le Fort I ⇒
most commonly done maxillary procedure for Class II & III
elongation/shortening
● Le Fort I ⇒
○ Also treats
facial asymmetry, OSA, max. atrophy
● Le Fort I ⇒
○ Osteotomy downfracture technique of maxilla →
allows for advancement/retrusion &
Surgical options for A-P discrepancy (Class II or III)
● BSSO (bilateral sagittal split osteotomy) ⇒
most commonly done mandibular procedure
○ To advance or retrude mandible
Surgical options for A-P discrepancy (Class II or III)
● Genioplasty (inferior border osteotomy
`
○ Increases or decreases prominence of chin (can help either class II or III)
○ Significant esthetic impact
Transverse discrepancies:
● Maxillary constriction →
most common transverse problem of maxilla
Transverse discrepancies:
○ SARPE
(surgically assisted rapid palatal expansion)
■ Suture fused, so midline osteotomy and then RPE
Transverse discrepancies:
○ 2 piece Le Forte I
■ Le Forte I split down the middle
■ Le Forte I, II, III ⇒ natural weak points of anatomy that surgeon cuts
Transverse discrepancies:
● Mandibular asymmetry → most common
mand. transverse problem (expansion/constriction rare)
Transverse discrepancies:
○ Distraction osteogenesis →
can corrects midline asymmetry
Transverse discrepancies:
○ Mandibular midline osteotomy
uncommon
Social-psychological status
● Many adult pts have underlying psychopathologic conditions which need to be managed (ie. depression)
○ Correction will not result in happiness for these pts
● Patients need to be internally motivated for long treatment times
● Discrepancies due to deficient growth →
finish growing earlier than excessive growth discrepancies & can be treated earlier
Sequence of treatment:
● Pre-surgical orthodontics
● Surgical procedure
● Post-surgical orthodontics
● Pre-surgical orthodontics -
orthodontic preparation for the planned surgical procedure ○ Eliminate dental compensations (ie. correct upper protrusion/lower retrusion in class III) ○ Dental alignment ○ Facilitates optimal surgery - although it make pt look worse (ie increases negative overjet in CL III), maximizes surgical outcome & pts feel better bc something’s being done
● Surgical procedure
○ Note: one of the least stable surgeries is
setting mandible back; may need elastics post-operatively
● Post-surgical orthodontics -
finishing & detailing occlusion
○ Keep post-surgical ortho to minimum
○ Potential for relapse if pt still growing (in case example pt had psychosocial issues, so had to start treatment earlier than ideal)
Surgery that stretches muscle/soft tissue →
more unstable
Exception to rule →
moving mandible forward stretches soft tissue & moving mandible back relaxes soft tissue
● Soft tissues don’t determine stability
Craniofacial Distraction osteogenesis (DO)
● Bone lengthening via gradual expansion of created osteotomy
● DO indicated for more severe situations -
can lengthen 2-3 cm
● Use DO over BSSO when you want
> 1 cm bone lengthening
Fracture healing phases:
● Inflammation → bone fractured
● Soft callus → soft tissue starts to form around & inside fracture site
● Hard callus → minerals start to form inside/around fx site; bone reunites
● Remodeling → newly formed bone remodeled; bone resorbed to its original condition
DO phases of healing
● Latency → phase between osteotomy & activation of distractor
● Distraction → when distractor activated & osteotomy gap widened
● Consolidation → distractor maintained & new bone formed inside gap
○ Gap becomes more radiopaque → indicates new bone formation
Distraction force ⇒ main driving force for new bone formation in distraction gap
● During early phase of distraction →
only minimal bone formation around distraction site
○ Direction of new bone parallel to distraction force
Distraction force
● By consolidation phase →
lot of new bone formation
○ General pattern of new bone follows
main direction of the distraction force
Ossification modes ⇒
intramembranous & endochondral (intermediate cartilage phase)
● Distraction has another ossification mode ⇒
transchondroid
○ Intermediate mode between endochondral & intramembranous
● All 3 modes occur at distraction site
Periosteum critical for
DO site bone formation
● Lateral side of mandible →
osteotomy entry site so greater trauma to periosteum than medial side
○ Medial side periosteum more intact →
so formation initially greater, but after weeks of consolidation, lateral side periosteum is restored & new bone formation on lateral side catches up to medial side
DO requires good
angiogenesis & blood supply
● Vessel formation during distraction; vessel mature during consolidation phase
DO site bone formation controlled by multiple factors:
Distraction factors, bone factors, other mechanical factors
- Distraction factors:
○ Latency time -
variable
■ Some believe craniofacial bone requires 5-7 days latency, while others believe no latency period required b/c of good blood supply
○ Distraction rate -
1 mm/day commonly used
○ Consolidation time -
at least double duration of distraction time
- Bone factors:
○ Blood supply & periosteum
○ Mesenchymal cells - differentiate into osteoblasts
- Other mechanical factors:
○ Stability of DO site
○ Functional loading
Advantages of DO
● No need for
bone graft (DO can grow bone)
Advantages of DO
● Significantly larger
bone movement ( > 20mm of mandibular advancement)
Advantages of DO
● Applicable to
infants & young children
Advantages of DO
● Can lengthen bone in
multiple dimensions simultaneously thru distraction vector control
Advantages of DO
● Surgical procedure less invasive than
conventional orthognathic surgery
Advantages of DO
● Less soft tissue resistance bc of
gradual distraction
Advantages of DO
● Better long term
stability & less relapse (?)
Advantages of DO
○ Studies show less relapse from DO at
8 weeks. But at 3 & 6 months → no significant difference (when compared to orthognathic surgery)
Advantages of DO
○ Maxillary protraction DO study →
no relapse at 2 years; better results with max. protraction, but only 1 study
Advantages of DO
● Mandibular DO →
less distortion & loading of TMJ than BSSO (?)
Disadvantages of DO
● Technique sensitive surgery
● Equipment sensitive surgery
● Less precise control for correction of occlusion
● Pt. compliance required
● Possible secondary surgery to remove devices (if internal distractor being used)
● Increased chance of infection
● Longer treatment time; increased number of office visits & higher cost
Indications for craniofacial DO
● Severe
micrognathia in infants & children with airway obstruction (ie. Pierre-Robine sequence)
Indications for craniofacial DO
● =========== with severe ———— hypoplasia
Hemifacial microsomia
mandibular
Indications for craniofacial DO
● Mx. deficiency ass. with cleft lip/palate ⇒
DO at Le Fort I level
Indications for craniofacial DO
● Mx. deficiency ass. with craniofacial dysostosis ⇒
DO at Le Fort III level
Indications for craniofacial DO
● Mandibular lengthening
> 10 mm
Indications for craniofacial DO
● Severe sleep apnea due to
Mx/Mn hypoplasia
Indications for craniofacial DO
● Widening of
constricted mandible
Indications for craniofacial DO
● Correction of syndromic
craniosynostosis & syndromic midfacial deformities
Contraindications of DO
● Lack of
adequate bone stock to distract - important; bone needs to be thick & strong enough
● Deficiency/defect can be corrected by traditional orthognathic surgery without bone graft
● Lack of pt compliance (pt needs to activate?)
DO vs. orthognathic surgery
● DO can be done in growing children
● Long-term stability unclear for both BO & traditional surgery; should only be used for severe cases
Camouflage treatment for skeletal problems
● Alternative treatment for non-growing or slow growing pts
● Best for pts with acceptable facial esthetics for minor to moderate skeletal problems
● Adjusts dental relationships with orthodontics &/or extraction
Camouflage treatment preference depends on
POV
● Traditionally Class II’s were acceptable for
females & Class III for males
● Newer data:
○ Consumers & oral surgeons believe that both Class II & Class III are more
acceptable in males than females
■ Moderate class II equally
acceptable in male & female
○ Orthodontists believe that Class II is more acceptable in
females than males
Class II camouflage treatment:
● Non-extraction →
elastics to retrude upper incisors; reduces overbite
● Extraction in upper or lower jaw
● Facial profile same?
Class III camouflage can be difficult
● Retrude lower incisors
● Start growth modification at
CVMS 2 or 3
○ Stage 3 indicates
peak growth
● CVMS cannot tell us when
growth stops; need to do serial cephs
● High-pull headgear ⇒
ideal use with high mandibular plane
○ Intrudes molars
● Cervical pull headgear ⇒
ideal use with low mandibular plane; deep bite
○ Extrudes molars (would make open bite worse)
Need to decide on camo vs. surgery initially →
bc extraction pattern are opposite
- Surgical cases occur at different times for maxilla & mandible (wait longer for mandible)
