Transcript
Prepared by:
Ashraf Qussous3rd year resident
Bjork 7 Structural Guideline
overbite depth indicator (ODI)
Is the angle the A-B plane makes with the mandibularplane combined with the angle of the palatal plane to the Frankfort horizontal.
PP-FH is positive it is added this value from AB-MP and vice versa.
A value of less than 68º is said to indicate an open bite tendency
Features of anterior open bite angle and/or long face syndrome
Skeletal feature
Tapered facial type. Long lower third of the face, Long maxilla Short mandible Short ramus Class II skeletal relationship Intraoral features Open bite Class 2 tendency Increased overjet Narrow upper arch Crowded LLS Growth feature Usually posterior growth rotation
Features of anterior open bite angle and/or long face syndrome
Cephalometric feature
Enlarged adenoid seeing in the ceph.
Increased dentoalveolar height in molar region and reduced dentoalveolar height in incisor region due to weak muscle allowing molar eruption. (Neilsen, 1991)
Bjork’s seven features of posterior growth rotation.
Jarabak ratio: 58 high angle case, reduced OB.
UAFH-LAFH ratio: less than 65%.
The overbite depth indicator (ODI) less than 68 degree.
Cephalometric feature
SN/MP angle 40º or greater
OP/MP angle 22º or greater
MxP/MnP angle 32º or greater
AOB negative overbite
PFH/AFH (Jarabak ratio) 58% or less
UFH/LFH 0.65 or less
Overbite depth indicator (ODI) 68
Features of anterior open bite angle and/or long face syndrome
Soft tissue features
Long lower third of the face.
Narrow nose.
Narrow alar bases.
Decreased naso-labial angle.
Incompetent lip.
Excessive exposure of maxillary anterior teeth and gingiva at rest and smiling which is due to dentoalveolar compensation of the anterior part of the maxilla to compensate for AOB.
Retruded chin.
Features of anterior open bite angle and/or long face syndrome
Intraoral features
Anterior Open bite. Class 2 tendency. Increased overjet. Narrow upper arch. Crowded LLS.
Growth feature Usually posterior growth rotation.
Etiology
Skeletal factors
Genetic Environmental
Juvenile rheumatoid
arthritis Trauma to TMJ Hormonal
Soft Tissue factor
Muscle of mastication
Neurological disturbances
Chronic nasal obstruction
Adenoids
Habit
Digit Sucking Habits.
Endogenous (primary) thrust
Eg. Downs-Syndrome
Treatment Stop the habit.
Myofunctional Therapy.
Myofunctional+EOA combination Therapy.
Extraoral Traction.
Fixed Appliances.
Molar intrusion using skeletal anchorage.
Repelling magnets.
Orthognathic Surgery.
Treatment of digit-sucking habits, BOS guidelines 2000
The child must want to stop.
A child who is undergoing severe psychological trauma is unlikely to respond to habit breaking.
The following methods for breaking the habit are listed in the order in which they should be used:
Treatment of digit-sucking habits, BOS guidelines 2000
A. Non-physical methodsI. Explanation.II. Reward.III. Habit reversal.IV. Teach the child to carry out alternative activities when they have the urge to suck the
digit.
A. Physical methods Reminder therapy like finger bandage, finger paint or thermoplastic finger post
A. Intra-oral appliancesI. Have been shown to be effective within 10 months.II. They must be fitted with the full understanding and co-operation of the child and
must not compromise compliance with any future orthodontic treatment.III. Fixed appliance like palatal appliance with crib.IV. Removable appliance.V. Functional appliance can stop habit .
Habit Breakers Appliances
1. Vertical Crib
Restrain the tongue from excessive anterior movement or thumb sucking.
A .040” support arch wire is soldered to bands on the first molars.
A vertical Cage is extended just behind the lower anteriors.
Habit Breakers Appliances
2. Flat Crib
For Thumb Sucking.
Wires are placed across the palate parallel to the occlusal plane to prevent the thumb from contacting the rugae.
This appliance is also less noticeable than a vertical Habit appliance.
Habit Breakers Appliances3. Rake
For patients that seem to get around all the other designs.
Vertical rake is extended just behind the lower anteriors.
Habit Breakers Appliances
4. Pearl
Restrain the tongue from excessive anterior movement.
A vertical cage is extended just behind the lower anteriorsto prevent the patient from tongue thrust.
A pearl is added in the vault of the palate to retrain the tongue.
Myotherapy
It aims to alter resting tongue and lip posture.
a. Exercise.
b. Appliances.
MYOTHERAPY Exercises1. Ask the patient to hold a piece of paper between the
lips. 2. The patient is instructed to practice correct swallowing
pattern by placing the tip of tongue on the palate, close teeth, close lips and swallow with tongue in that position. After the new swallowing pattern learned on the conscious level, it is necessary to reinforce in subconsciously. Flat, sugarless fruit drops are used to reinforce subconsciously by asking the patient to hold fruit drops against the palate.
3. Ask the patient to squeeze teeth together as hard as possible for 15 secs, relax and repeat three times for total of one minute. This exercise should be done five times a day (Clenching exercises).
Myotherapy appliances1. Spring-loaded bite block, the spring-loaded bite block has helical springs
that are placed both lingually and buccally between the first premolar region and the last molar region. The ends of the springs are embedded occlusallyin the molar regions of the acrylic part of the device. The upper and lower acrylic occlusal blocks are connected by palatal and lingual wires, which are activated to a force of 450 g bilaterally. Patients are instructed to use the appliance for an average of 16 h daily
2. Passive posterior bite-blocks, are functional appliances that are used to open the bite 3–4 mm beyond the rest position. In growing patients, this inhibits the increase in height of the buccal dentoalveolar processes, thus preventing a downwards and backwards rotation of the mandible. It also allows differential eruption to occur as the labial segments can erupt unhindered, hence closing the AOB.
3. The functional regulator appliance (FR IV).
4. TwinBlock with modifications.
Frankel FR- IV It establishes the mandible forward rotation with
posterior edges of buccal shields as rotational centers.
Anteriorly: the force of anterior vertical muscle chain being strengthened by lip seal exercise raises the mandible.
FR -IV
FR-IV OWEN s modification of a function regulator differs
from other Frankel appliances by:
a. Addition of posterior acrylic bite blocks to arrest molar eruption.
b. Has headgear tubes that accept a facebow for an occipital pull headgear, which provides the appliance with positive control of the posterior maxilla.
Frankel IV
Frankel IV Cochrane review, by Oliveira, in 2007showed that
there is weak evidence that the interventions FR-4 with lip-seal training and palatal crib associated with high-pull chin cup are able to correct anterior open bite.
Twin blocks with modifications
1. Thick Twin block appliance: The ramps measure 5 mm to 8 mm in thickness in the premolar region. Twin block with headgear to upper 1st molar.
2. Vertical elastics to upper and lower posterior premolar regions.
3. Repelling rare earth magnets in the occlusal bite blocks
Twin-Block with posterior bite blocks :
Bite anterioposteriorly is irelevent to the deep bite correction
Bite is be opened above the normal resting vertical dimention.
Blocks on molars prevent their eruption, and the opening of the bite stretch the muscles.
Extraoral Traction
1. Vertical pull chin-cup
2. High-pull headgear applied to the maxillary molar teeth worn for 14 hours per day has been used to inhibit eruption of the posterior teeth and hence limit vertical growth
High pull headgear to a maxillary splint.
High pull headgear to buccal splint.
Headgear can be applied directly to the upper molar bands of a fixed appliance
Fixed Appliances
1. Extraction of terminal molars
2. Bracket set up (more gingival at anterior teeth, reduced canine tipping)
3. Wire bending to allow incisor extrusion
4. Tongue timer which act as a tongue thrust breaker
5. Vertical intermaxillary elastics to extrude the anterior teeth. Should not be used if the etiology is primarily skeletal.
6. Segmental arch mechanics to extrude the incisor similar to Rickets mechanics.
7. Kim mechanics & Modified Kim mechanics.
Kim mechanics
Increased curve of Spee in the maxillary arch and a reverse curve of Spee in the mandibular arch combined with anterior elastics.
Size of anterior elastic is 3/16 heavy
Force is 50g when closing
150g when opening.
Molar intrusion using skeletal anchorage
LikeDental implants, mini-plates, mini-screws ,ankylosed teeth (Cousely 2008 use TPA with two palatal TAD for posterior teeth intrusion, while Etilitaet al 2012 use TPA with two buccal TAD). Park et al (2008).
Intrusion of the molars is best suited to skeletal open bite patients who show long face types with class 1 or mild class 2 skeletal patterns whereas in class 3 open bites, the class 3 malocclusion would get worse as the anterior open bite closed
Patients who do not show sufficient incisor exposure should not be treated by molar intrusion, making the more conventional method of incisor extrusion a more suitable option for open bite correction
This can be achieved by
placing miniscrews on both the buccal and palatal,
using a transpalatal bar or a splint
An alternative design of splint
Mid Palatal Implant
Disadvantages of buccal implants1. The inter-radicular space between the first molar
and the second molar is very small.
2. In open bite cases, as the posterior teeth being intruded, the screw becomes closer to the alveolar crest and the periodontal membrane.
Disadvantages of buccal implants In most of cases, the inter-radicular space between 6
and 7 is narrow.
Then, it is inevitable to place a mini-implant between 5 and 6.
The mechanical efficiency to intrude the posterior teeth will be decreased & Possibility of Root trauma is high.
Orthognathic Surgery
Where there is an obvious step in the occlusal plane, two piece maxilla.
No step, one piece maxilla.
Subapical osteotomy of the anterior (Kole technique) or posterior segment (Schuchart technique) depend on the etiology.
Recently Bisase 2009 recommend anticlockwise rotation of BSSO with rigid fixtion.
Stability of AOB
In general: AOBs treatment is stable in approximately 80% of treated cases with slightly better with surgical treatment than non-surgical (5% differences).(Huang, 2002)
Extraction: There is also evidence of greater stability of open bite correction when orthodontic treatment is undertaken with extractions (Janson et al., 2006)
Extrusionorintrusion: In treatment resulting in molars intrusion, the rate of relapse ranges from 17 to 30%: whilst in treatments with incisor extrusion, relapse may be even greater, reaching sometimes 40% of treated cases. (Suguwara 2011)
Causes of relapse
a. Continued unfavorable posterior mandibular growth rotation
b. Unfavorable tongue position
c. Continued habit
d. Excessive extrusion of incisors
e. Relapse after surgery
Management of relapse
1. Overcorrection
2. Using High-Pull headgear attached to a URA
3. Retainer with passive bite blocks, which supposedly place intrusive forces on the posterior teeth, could be used & should be continued until facial growth has almost ceased and this is often well into late teens.
4. Some recommend lip and tongue muscle exercises.
Skeletal class 2 with Long Face
Can be treated successfully by the intrusion of the posterior teeth as this would produce a closing counterclockwise rotation of the mandible with a shortening of the anterior facial height and a correction of the open bite, in addition to the reduction of OJ.
In grower with High-Pull Headgear.
In non-grower By TADs
Case report of class 2 high-angle in 12 year old patient
Classification of deep bite
Classification
Developmental deep bite
Skeletal deep bite
(horizontal growth pattern)
Dento-alveolar deep bite
Inter occlusal clearance
(functionally a pseudo deep over bite)
supra occluded incisors
Acquired Deep Bite
Lateral Tongue Thrust , Infra Occluded
Posterior Teeth e.g. class II div 2
Early loss of Deciduous Teeth, Tipped
Contiguous Teeth (Acquired Secondary
Deep Over Bite)
Wearing of OcclusalSurface or Tooth
abrasion
Dento-aleveolar
Skeletal
Features of low angle or short face syndrome
Skeletal features:
a. Short lower third of the face.
b. Class II skeletal relationship.
c. Long maxilla.
d. Short mandible.
e. Broad square facial type.
Features of low angle or short face syndrome
Soft tissue features:
a. Increased exposure of maxillary anterior teeth and gingiva at rest and smiling.
b. Competent lip.c. Acute LMA & NLA.d. High lower lip line.e. Hyperactive mentalis. f. Hypertrophied masseter.g. Prominent chin.
Features of low angle or short face syndrome
Intraoral features:
a. Deep bite.b. Class 2 Dev2 tendency. c. Reduced overjet.d. Wide upper arch.e. Lower incisor trapping behind upper incisors.
Growth feature: Usually anterior growth rotation.
Cephalometric featurea. UAFH-LAFH ratio: less than 0.65 are considered to
be poor risks for conventional orthodontic treatment alone.
b. Bjork’s seven features of posterior growth rotation.
c. Jarabak ratio:
PFH:AFH, 59 – 63% is normal; if > 64 low angle case then the case is deep OB; if < 58 then the case is high angle case, reduced OB.
Aetiology deep
overbite
Skeletal Factors
Soft TissuesDental factors
Growth Factors
Skeletal Factors1. Antero-posterior problem:
Class II skeletal pattern with loss of occlusal contact allowing the incisors to overeupt or the mandible to rotate anteriorly.
2. Vertical problem:
A reduced lower face height in conjunction with a class II jaw relationship often results in the absence of an occlusal stop to the lower incisors, which then continue to erupt leading to an increased overbite which exaggerated by anterior growth rotation of the mandible.
Growth Factors
In forward growth rotation and loss of incisor stop an increased overbite will become worse unless the incisors have an occlusal stop.
Soft Tissues
a. High lower lip line: The higher the lower lip line, the more retroclined the upper incisors and the deeper the overbite.
b. Hyperactive or “strap- like” lower lip.
c. Hyperactive Mentalis muscle: causing retroclination of the upper incisors and then increase in the OB.
d. Hyperactive Masseter muscle.
Dental factors.
Diminution of palatal surface (cingulum) of the upper incisor crowns.
Increased Incisors height.
Iatrogenic Factor
In the case of treating Class II division 1 and instead of finishing the case into Class I, it is finished into Class II division 2 causing deep incisor overbite.
Management of Low Angle cases
Treatment modalities in growing and non growing patients.
1. Growing patients:
a. Intrude anteriors.
b. Extrude posteriors.
c. Combination of posterior eruption and anterior intrusion.
2. Non growing patients (little or no growth expected):
a. Orthognathic surgery.
b. Intrusion of anteriors (posterior extrusion invariably relapses).
Soft Tissue consideration
Depending on Inter occlusal space
Dental and Skeletal consideration
Considering Growth pattern
Mechanics for overbite reduction
Mechanics for overbite
reduction
Extraoral traction Dahl appliancesRemovable Appliances
Fixed appliance
Bracket settingIntermaxillary
mechanics Fixed anterior
bite planes.Archwires:
Rocking chair NiTi arch wires
Segmented Burstone Arch
Wires mechanics
Rickett’s utility arch
Absolute Anchorage
OrthognathicSurgery
Removable AppliancesAnterior Bite Plane
Indications:
a. Growing patient.
b. With a short lower facial height.
c. Excessive curve of Spee.
d. Other uses include protection of the lower incisor brackets from being debonded.
Extraoral traction
1. J hooks: (Linge and Linge 1983 show that J hook cause root resorption). Degushi 2008 compared TAD with J hook for intrusion and found the result is 3.1 and 1.3mm respectively.
2. Cervical pull HG to molars
Functional Appliances
The modes of action in reducing the OB are:
a. By allowing the posterior teeth to erupt either during the active functional appliance through relieving of the acrylic from the lower part of the TB or during transient period through the use of steep and deep URA.
b. Through changing the direction of growth pattern
c. By some proclination of the lower labial segment may occur
Fixed appliance setting
1. Increase mesial angulation of the upper canines.
2. Bracket Positioning
3. No laceback or cinch back
4. Banding second permanent molar. This means:
Additional vertical posterior anchorage
Molar therefore a more effective wedge in extrusion is more distal and the occlusion.
Rocking chair NiTi archwire
It acts by intrusion of anterior teeth.
Extrusion of posterior teeth.
Proclination of anterior teeth.
It can be used to treat AOB with Kim mechanics.
Earlier engagement of brackets with a rectangular wire is possible, which may speed overbite reduction.
long range of action
Disadvantages of Rocking chair NiTiarch wires
Molar rotation distobuccally.
Molar rolling buccally.
Premolar expansion.
Incisor proclination.
Asymmetric bite opening sometimes occurs.
Contraindicated in extraction cases(difficulty of space closure).
Segmented Burstone Arch Wires mechanics
AW which is a segmented base arch wire (so that there is no connection along the arch between the anterior and posterior segments) and an auxiliary depressing arch.
The buccal segments are first aligned, and then stabilised using a full dimension rectangular arch wire. The same for anterior segment
In addition to this, a heavy lingual arch is used to connect the right and left posterior segments.
An auxiliary depressing arch is then placed in the auxiliary tube on the first molar and is used to apply force against the anterior segment.
It is recommended that no more than the four incisors should be incorporated in the intrusive segment, since if the canines were also included, this would shift the anchorage balance unacceptably towards distal tipping of the buccal segment teeth.
018x.025ss wire with a two and a half turn helix. .019x.025 TMA without a helix.
Segmented Burstone Arch Wires mechanics
The wire should lie just gingival to the incisor teeth when passive, and applies a light force of 10-15g when activated.
The Burstone intrusion arch is tied beneath the brackets, not into the bracket slots, which are occupied by the anterior segment wire.
It still has the effect of wanting to tip the incisors forward as they intrude, but two strategies may be employed to prevent this:
The arch wire may be tied back against the posterior segment –however, this can put some strain on the posterior anchorage.
The point of force application may be altered by tying it more distally. The force is then closer to the labial segment’s centre of resistance – this prevents incisor proclination without straining posterior anchorage.
Segmented Burstone Arch Wires mechanics It still has the effect of wanting to tip the incisors forward
as they intrude, but two strategies may be employed to prevent this:
a. The arch wire may be tied back against the posterior segment – however, this can put some strain on the posterior anchorage.
b. The point of force application may be altered by tying it more distally. The force is then closer to the labial segment’s centre of resistance – this prevents incisor proclination without straining posterior anchorage.
Rickett’s utility arch
step-down bends labial root torque to control the inclination of the teeth as the
incisors move labially while they intrude.
Indications for segemental archwires:a. Adults.b. Deep overbite with the incisors are upright and the canines
distally angulated and an intrusive force anterior to the centre of resistance of the incisors in the early stages is quite helpful.
c. Highly positioned canines with overerupted incisors.d. Gummy smile.e. Orthodontic decompensation for AOB case treated by
segemental surgery.
Advantages of segemental archwires:
a. A long range of action, because of the long inter-bracket span.
b. More easily estimated biomechanical effects.
c. Frictionless.
Disadvantages of segmental mechanics:
a. Complexity of fabrication.
b. Less ‘fail-safe’ effect if the case is unsupervised for a period.
c. Oralhygiene difficulties and patient discomfort if the wires impinge on the mucosa.
d. Poorercontrol of overall arch form; bypass arch systems limit the amount of true intrusion that can be obtained:
Extrusion of the first molar can occur through distal tipping of molars as it is the only tooth available as posterior anchorage – high-pull headgear may need to be used, especially in non-growing patients.
the intrusive force against the incisors is applied anterior to the centre of resistance – causes incisors to tip forwards as they intrude.
Rickett’s utility arch
Functional appliances
For class 2 and reduced facial height.
Treatment of choice when having growing class 2 patient with deep bite.
Proclination of lower incisors reduces deep-bite.
They might change the direction of grwoth to downward-forward direction.
Class 2 elastics Helps in lower molar extrusion.
Although can cause upper incisors to retract, the effect is much less than lower molars extrusion, since they are closer to the hing axes.
Upper rect. Steel can reduce the effect of retroclination of upper incisors.
Surgery
3 point landing, followed by premolar extrusion.
Segmental surgery eg: Kole procedure.
If a growing patient presented to you with:
Low angle class 2?
High angle class 2?
Low angle class 3?
High angle class 3?
Stability of OverBite
1. Avoiding change in the facial height in non-growing.
2. Long term retention if LLS proclined.
3. Amount of the OB at the start.
4. Normal InterIncisal angle.
5. Normal lower incisor edge to centroid.
6. Build up diminutive cingulum plateau.
7. Vertical height growth continue in teenager so the use of URA with ant bite plane as part time use in retention.
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