Transcript Direction of force The direction offorce should be applied

IN THE NAME OF GOD
Force eruption
Dr:Nahvi
Force eruption
• Unerupted tooth
• Fractured tooth
Tooth eruption
A permanent tooth should erupt:
6 months after natural exfoliation of its predecessor
Eruption delayed :
if the interval extends to more than 1 year.
Eruption of a tooth is considered to be
delayed :
• The normal time for eruption has been
exceeded.
• The tooth is not present in the dental arch and
shows no potential for eruption.
• The root of the unerupted tooth is completely
formed.
• The homologous tooth has been erupted for
at least 6 months.
J Can Dent Assoc 2010
Most commonly become impacted
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third molars
maxillary canines
maxillary central incisors
mandibular second premolars
Causes of Delayed Eruption
• Localized
• Generalized
Localized
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the presence of supernumerary teeth(most common )
Odontoma
dilaceration
malpositioning of the tooth germ
Crowding
calcifying odontogenic cyst
trauma to the corresponding deciduous tooth
systemic conditions
• cleidocranial dysostosis
• hypothyroidism
• Gardner syndrome
• Down syndrome
Criteria for Treatment
• chief complaint
• At least 3 mm of bone
• The tooth is mature
J Can Dent Assoc 2010;76:a147
Alignment of an impacted tooth
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position and direction
degree of root completion
degree of dilacerations
presence of space
Treatment planning:
1-surgical exposure
2-Attachment to the tooth
3-Orthodontic mechanics
surgical exposure
• (1) exposure of the entire labial aspect (the
window approach)
• (2) a technique which exposes only 4–5 mm
of the labial aspect
Attachment
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Gold chain
Band
Cast gold crown,onlay
Threated pin
Wire loop
Direct bond attachment(the best)
General characteristics of orthodontic
Forces
• Optimal:light,continuous
-Ideal material
Maintains elasticity
Maintains force over a range of tooth movement
Force
• Continuous
• Interrupted
• Intermittent
• Extrusion
35-60gr
Continuous
Interrupted
Intermittent
Contemporary orthodontics
Direction of force
parallel to the long axis
avoid torquing forces
Oral Maxillofacial Surg Clin N Am 16 (2004) 75-89
Force eruption
Fixed appliances
Removable appliances
• Fixed appliances
Do not require special patient cooperation
precise coronal and root movements
• Removable appliances
less chairtime
better oral hygiene
More esthetic
Removable appliances
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retention clasps
labial bow
Hook(for attachment of elastics)
Finger spring,Zspring,Canine retractor
Removable appliances
• at least 10 hours per day.
• Rest intervals,not to exceed five hours per
day.
• wear the appliance 24 hours a day, removing it
only for meals
• the elastics should be changed every two or
three days.
• Lingual tipping will be minimized when the
labial bow is used for the extrusive force
JCO/JULY 2002
Fixed appliances
coil :
• maintains the space
• anchorage and balancing resistance
J Can Dent Assoc 2010
• Anchorage support for the extrusion—a minimum of one
tooth on either side of a single-rooted tooth (2 anchors)
or
two teeth on either side of a multi-rooted tooth (4 anchors)
Use a heavy square or rectangular NiTi wire to minimize tipping
J Can Dent Assoc 2010;76:a147
Magnetic force
• For a patient with other missing teeth
Contemporary orthodontics
• Elastics
-light
-medium(1/8 =3.18mm
-heavy
127.58gr)
Orthodontic Elastics (3/8", 5/16", 1/4", 3/16",
1/8")
Shiraz Univ Dent J 2009; 10(1):7-15
clinical problems (canine)
1) Lateral root resorption
2) External cervical resorption
3) Dentoalveolar ankylosis
4) Calcific metamorphosis of the pulp
and aseptic pulp necrosis.
Dental Press J Orthod. 2010 Nov-Dec;15(6):18-24
Thank You