extraoral orthodontic appliances / for orthodontists by almuzian

Mohammed Almuzian

BDS (Hons), MSc.Orth (Distinction), MSc.HCA/Merit (USA), Doctorate ClinDent.Orthodontics (Glasgow), FIADFA (USA), MFDSRCS

(Edinburgh), RCS (Ireland), RCPSG (Glasgow)., MJDFRCS (England), MOrth.RCS (Edinburgh), MRCDS.Ortho.(Australia), IMOrth.RCS

(England/Glasgow)

To understand :

1. Historical background

2. Types & designs of extra-oral appliances

3. Uses

4. Complications & Safety regimes

5. Force effecting factors

6. Treatment timing

Extraoral appliances have specific uses in orthodontic biomechanics.

Clinicians using retraction headgear and protraction headgear should be familiar with

their clinical indications, the potential problems and how these can be avoided.

To develop the knowledge of the specialist orthodontist in relation to extraoral

appliances in orthodontics.

An appliances that provide a means of applying anterior, posterior or vertical directed forces to the dentition and skeletal complex from an extra-oral source.

Almuzian et al 2013

Introduced in the late 1800's by Kingsley then by Angle in 1910. By 1920, it was disused as it was believed that intra-oral elastics would

suffice (Angle). Re-used again in the 1940's after lateral cephalometric radiographs

showed the adverse effects of intra-oral elastic traction declined over the last 20 years with the refinement of non-compliance

based treatment modalities including temporary anchorage devices. The use of protraction headgear has increased as more evidence of its

effectiveness for the treatment of Class III malocclusion has become available.

1. Headgear with facebow or J hook.

2. Reverse facial mask

3. Chin cap

1. Anchorage appliances

2. Active dental appliance

Retraction movement

Transverse teeth movement (minor maxillary dental expansion)

Vertical teeth movement (intrusion or extrusion of UBS or ULS)

3. Growth modification or orthopedic appliances

1. Anchorage appliances

Increasing anchorage and prevents forward movement of anchor teeth

Space maintainer

2. Active dental appliance

Retraction movement a. Distalize UBS To correct less than 1/2 unit CL2 molar relation

To provide space to relief mild crowding

To correct mild increased in the OJ in non-extraction cases.

To provide extra space in sever space deficiency in which extraction fail to provide sufficient space.

To provide space for spontaneous eruption of ectopic canine as interceptive treatment with a success rate of 80% compared to 50% in control group.(Leonardi, 2004).

To regain a lost space due to mesial migration of molars (premolar crowding cases).

Uprighting impacted U6s against UEs.

2. Active dental appliance

Retraction movement

b. HG with J hook to retract ULS or U3

c. Rarely, retract LLS or L3 (problem with patient toleration)

d. Differential (asymmetric) movement for treatment of ML problems

Atherton et al. (2002) came to the conclusion that the most distal movement of the molars that could be achieved was in the range of 2 -2.5mm

Melsen and Dalstra (2003) in their retrospective study found that the total displacement of the molars in patients wearing cervical headgear for a 8-month period did not differ from that of an untreated group when re-evaluated 7 years later

2. Transverse teeth movement (minor maxillary dental expansion)

3. Vertical teeth movement (intrusion or extrusion of UBS or ULS)

3. Growth modification or orthopedic appliances

It acts by influencing the pterygopalatine, fronto-maxillary, zygomatic maxillary sutures.

Studies regarding the effects of HG RCT by Tulloch (1997) early treatment with

headgear or functional appliance therapy can both reduce the severity of a class 2 skeletal pattern. 75% chance of this occurring.

Mills 1978 in a review, stated a maxillary growth suppression effect of 1-2 mms is possible in humans with Kloehn bows

1mm of maxillary growth restraint achieved over a 10 year period that persists post-treatment (Wieslander, 1993)

1. Original Kloehn bow invented by Kloehn 1947 after world war II

2. Kloehn loop style facebow

3. Asher Facebow

4. Bite Plate Facebow

5. J hook facebow (not used anymore in UK for safely reasons)

6. Asymmetric HeadgearPOWER-ARM FACE-BOW

SOLDERED-OFFSET FACE-BOW

SWIVEL-OFFSET FACE-BOW

SPRING-ATTACHMENT FACE-BOW

7. Nudger appliance HG

8. Headgear to upper part of the Twin block

9. The Intrusive Myofunctional Appliances THE VAN BEEK APPLIANCE

The Buccal Intrusion Splint (BIS)

The Maxillary Intrusion Splint (MIS)

The Maxillary Intrusion Splint and Lower Traction Plate (CONCORDE)

Original Kloehn bow invented by Kloehn1947 after world war II

Kloehn loop style facebow

Asher Facebow

- Used by Dr. Ron Roth- Intrudes anterior teeth- Pushes on Archwire

Bite Plate Facebow

- Intrudes anterior teeth- Pushes on anterior teeth- two main styles:loop style or regular style

J hook facebow (not used anymore in UK for safely reasons)

J hook traction engaged in stops soldered or crimped onto the archwire between the lateral incisor and the canine or attached to an attachment on the tooth directly.

Hickman (1974) -devised a headgear which will accept 2 or even 3 "J" hooks each side.

Uses of J hook HG

1. Translate the U or L canine distally.2. If force heavy enough - then it can move 5/5

and 6/6 distally also.3. It also restrains maxillary development. 4. "J" hook headgear can also be used

asymmetrically to resolve a centre line problem by judicious use of the hooks to contralateral upper and lower canines e.g. UL3 & LR3.

Problems of J hook:1. Accidental injuries 2. Root resorption.3. "J" Hook straight pull headgear to the lower

arch in Class III cases cause the mandible to rotate in clockwise direction.

4. "J" Hook to fixed appliance archwire -important to contract the arch wire from the canines distally in order to resist the headgear's expansion effect on the arch wire (Berman, 1976).

Asymmetric Headgear

results in more movement on the side with the longer outer bow according to Castagliano's Theorum

It will also lead to that same tooth becoming susceptible to lingual crossbite

1. POWER-ARM FACE-BOW

2. SOLDERED-OFFSET FACE-BOW

3. SWIVEL-OFFSET FACE-BOW

4. SPRING-ATTACHMENT FACE-BOW

Nudger appliance HG

Band molar teeth; fit URA with palatal cantilever spring 0.7mm SS on the molar requiring distal movement.

Retention from premolars and incisors

Used for true unilateral space loss

Alternative ways of differential movement of 6/6: asymmetrical extraction of the 7s with normal Kloehn Bow and/or URA screw appliance

Headgear to upper part of the Twin block

The Intrusive Myofunctional Appliances

THE VAN BEEK APPLIANCE

Described by Pfeiffer (1972) to reduce the duration of treatment significantly.

This prompted Van Beek to design a simplified short outer arm facebow embedded in the acrylic part of the Harvold activator (Myotonic functional appliance)

Modifications of the combined activator and headgear were described by Teuscher, Thurow, and Bass

300 gms of force/12 hours a day

The Intrusive Myofunctional AppliancesThe Buccal Intrusion Splint (BIS) This appliance consists of an acrylic palatal

baseplate which is clear of the upper anterior teeth and with occlusal capping on the teeth in occlusion. There are double Adams cribs present on the upper first permanent molars and second premolars and molar tubes embedded in the occlusal capping acrylic to accept a Kloehn facebow. There is a midline screw present in the palatal acrylic

The Intrusive Myofunctional Appliances

The Maxillary Intrusion Splint (MIS)

This appliance consists of an acrylic baseplate which extends over the occlusal surfaces of all teeth and onto the labial surfaces of the upper anterior teeth. There are headgear tubes present within the molar capping

The Intrusive Myofunctional Appliances

The Maxillary Intrusion Splint and Lower Traction Plate (CONCORDE)

This is a two part appliance which consists of a maxillary intrusion splint and the lower appliance consists of an acrylic baseplate with lingual hook on the lingual aspect of the acrylic baseplate to enable elastics to be attached to the midpoint of the facebow.

Teeth related

1. Anterio-posteriorly:

Worsening of Class III relationship

Distal tipping of the teeth

Incisor retroclination.

Teeth related

2. Transversely:

Increased crown buccal torque (reduced by rigid TPA).

Scissor bite effect of J hook ,cross bite effect of Kloehn bow and asymmetrical HG( in the latter situation, this adverse tooth movement can be counteracted with either a removable upper appliance with screw expander or by widening (expanding) the inner bow).

Teeth related

3. Vertically:

Reductions in the OB in case of low pull HG.

Increase anterior facial height and gingival show due to mandibular clockwise rotation as a result of molar extrusion and the patient will show CL2 profile (O'Reilly et al.1993).

Teeth related

4. Disto-lingual or mesio-buccal rotation of the molars and canines

5. Root resorption is a possibly with J hook headgear and this should be monitored radiographically, e.g. long cone Periapical

Patient related

1. Patient Cooperation

Not all patients are honest in actual compliance. Using time charts can increase co-operation (Cureton et al. 1992, 1993).

Patient related

2. Biological variability: Growth may be unfavorable

3. Pain

4. Difficulty with insertion

5. Nickel allergy – Contact dermatitis-type IV delayed hypersensitivity immune response (Rahilly and Price, 2003).

Patient related

6. Extra/Intra-oral injuries: Eye injuries

(Samuels and Jones, 1994; Booth-Mason and Birnie, 1988)

Rarely eye injuries can occur whilst wearing headgear

Serious consequences (ocular bacteria infection, impaired vision, loss of eye, sympathetic opthalmitis, cavernous sinus thrombosis) - Chaushu, 1997.

Safety headgears (Anti-recoil device)

Means that they are design to break-away when excessive force applied to HG. NOLA SYSTEM: same as anti-coil device but the device attached to the face bow not the HG

Safety facebows

a. Locking mechanism: helps to avoid accidental remove of the facebow which act by special locking device behind the distal end of the inner bow thus preventing accidental dislodgment of the facebow.

Safety facebows

b. (re-curved reverse entry inner bow) designed by Lancer Pacific but it is difficult to use by the patient.

c. SAFE END (blunt end)

d. LOCATING ELASTIC. Like CLASS 1 elastic attached the inner bow to the teeth to stabilize the facebow.

3. Miscellaneous safety products

MASEL SAFETY STRAP (rigid neck strap) easy and cheap. Works by adding a additional rigid safety strap to the HG to minimize facebow movement and dislodgment.

4. in case of HG+URA.

a. CLIP-OVER APPLIANCE. It means that the facebow should attached securely to molar band while the URA clip over the bands

b. INTEGRAL FACE BOW (soldering the inner bow to the URA)

c. LOCKING MECHANISM (same as point B)

5. INSTRUCTION

Written and verbal advice for example:

At night always ensure that the safety mechanisms

If the headgear comes detached during sleep, stop wearing the headgear immediately and contact your orthodontist the next day.

Remove external headgear attachment before the inner bow. Never remove or fit the headgear in one piece

Do not wear headgear while playing sports.

If any eye injury associated with the headgear occurs; it must be treated as a Medical emergency.

Bring your headgear to each appointment and report any problems to your orthodontist.

Samuels 1994 (23 countries studied)

1. Accidental disengagement while playing (17%)

2. Incorrect handling during fitting or removal (8%)

3. Bully pulls headgear (4%)

4. Unintentional nighttime disengagement (71%)

According to the study of Stafford on 1998, the ideal safety system should have the following features:

1. Extension: it means the amount of extension of the facebow from its attachment with the molar bands before it break-away (stop releasing force). So if accidental force applied in a direction to dislodge the facebow, this system (Anti-recoil device) will start working

2. Force: it means the amount of force applied to the facebow before it stops release the force or break-away (Anti-recoil device)

3. Consistency: which means the release point should be constant in all types of HG after prolonged repeated use.

High pull headgear is claimed to intrude the first molars or at least reduce their vertical development. The point of application of the force however tends to result in more intrusion of the buccal cusps than the palatal cusps. A transpalatal bar is mandatory under these circumstances.

In a study by Wise et al (1994) which compared 20 non-extraction patients in which a transpalatal bar was used for at least 5 months with similar patients in whom it was not used, no significant differences were found between the two groups. The transpalatal bar design used was fitted 1-2 mm off the palate.

◦ Direction Theory of Directional Forces (DF) - Merrifield and Cross

(1970), DF angle = "directional force angle" = angle made by the headgear line of force and the functional occlusal plane.

If DF > 60º. (vertical pull) - a force is produced which is 0 distal movement and 3/3rds intrusion upon 6/6.

If DF 20-50º. (high pull) - a force is produced which is 1/3rd distal movement and 2/3rds intrusion upon 6/6.

If DF = 0-10º. (straight pull) - a force is produced which is 3/3rd distal movement and 0 intrusion upon 6/6.

If DF = -10 to -20º (low pull) - this gives the force which is 1/3rd extrusive and 2/3rds distal upon 6/6.

Position in relation to centre of resistance Outer Arm short -.

If above centre of resistance i.e. high pull - causes intrusion and distal tipping of the root.

If below centre of resistance i.e. low pull - causes extrusion and distal tipping of the crown.

Outer arm long –

If above centre of resistance i.e. high pull - causes intrusion and distal tipping of the crown.

If below centre of resistance i.e. low pull - causes extrusion and distal tipping of the root.

Outer bow at the trifurcation point of 6/6 (centre of resistance. The result is pure translation.

◦ Magnitude

Different level of force for different requirements (and different clinicians!)

I have recently placed HG to distlize UBS at a force of 500g per side

Weislander (72) achieved 2mm of distillation of A point over 3 years with only 300g of force

Armstrong (1971), Graber (1977) all used forces in excess of 400g, and sometimes 2 or 3 times that amount to achieve rapid orthopaedic translations

Firouz (92) showed that the rate of anterior displacement of A point was significantly decreased by applying 500g.

Watson (1978) demonstrated that the ANS could move distally by as much as 4mm in 1 year by applying 1000g bilaterally

Conclusion:

(higher force cause growth restraints)

Force levels of 250-300g per side is adequate for anchorage

Force levels of 400-500g per side is adequate for teeth movement.

Force levels of 800-1000g per side is adequate for skeletal effects

Duration (longer duration cause teeth movement and growth restraints)

Supportive (anchorage) 10 hours per day

Active (distal movement12-14 hrs minimum/day (100 hrs/week).

Orthopaedic - 12-14 hours per day.

Cureton et al. (1993) recommend the use of headgear charts routinely.

(Clark et al 2003) monitoring device like the Affirm headgear traction module has been used (electronic timer)

• functional appliances which have better compliance

• fixed functionals

• more class 2 elastics being employed

• self-ligating brackets seem to reduce anchorage demands (not proven) and favour earlier use

of lighter class 2 traction

• more lower incisor proclination accepted

• more arch expansion accepted

• TADs have revolutionised intra-oral anchorage possibilities

Definition

Means of applying anterior directed forces to teeth and/or skeletal structures from an extra-oral source

History

The technique of maxillary protraction is based on work by Nanda (1978), with rhesus monkeys in which he showed that a force of approximately 500g could produce anterior displacement of the maxilla

It is appropriate to refer to this type of treatment as facemask therapy.

Uses Treatment of maxillary retrusion Dental protraction allowing closure of space

from behind in patients suffering from hypodontia

Stabilization following maxillary osteotomy/distraction osteogenesis

Rotate arch segments in cleft palate patients Remove hyper-anterior contact in TMJ

internal derangement cases, Reinforcement of anterior anchorage

1. Correction of a centric occlusion-centric relation discrepancy. This correction happens relatively rapidly in patients with an edge to edge relationship and associated displacement

2. Maxillary skeletal protraction, with up to 3mm of forward movement of the maxilla possible

3. Forward movement of the maxillary dentition

4. Lingual tipping of the lower incisors (except suborbital types)

5. Redirection of mandibular growth in a downward and backward direction, resulting in an increase in lower anterior facial height

Depending on dental age

McNamara (1987) suggested that the optimal time for treatment is in the early late mixed dentition, coincident with the eruption of the upper permanent incisors.

Depending on the chronological age

Other investigators have suggested that for optimal orthopaedic effects, treatment should be initiated before the patient is 9 years old ( Proffit, 2000).

Depending on the skeletal age

The early treatment group (CV3-CV4) showed effective forward displacement of the maxillary structures whereas the late treatment group (CV5-CV6) showed no change compared with controls . Baccetti et al (1998)

Force

1. Moving maxillary anterior teeth forward: 400g per side

2. Forward movement of lower molars : 600g per side

3. Maxillary sutural protraction : 800g per side

NB:

To avoid bite opening, place protraction elastics near maxillary bicuspids

Avoid Class III elastics as they rotate occlusal plane

Pay special attention to airway and tongue posture

Overcorrect to compensate for mandibular growth

Mild to moderate skeletal III base

Better results with average or reduced lower face height. Yoshida et al (2007)

Patient 8-10 years of age

• Protraction Headgear (Hickham)

• Facial Mask (Delaire)

3. Suborbital Protraction Appliance (Grummons)

-uses, forehead,backof head and zygomatic areas for support -advantages-frame more rigid, no force on TMJ,easy to adjust and wear during sleep

-Disadvantages- not esthetic due to midfacial support

4. Nola protraction appliance

Petit style face mask

The Petit style with a single central vertical bar is also well tolerated and recent price changes have made it economically much more attractive

Rapid maxillary expansion seeks to exploit two effects:

1. the forward movement of the maxillary complex which often accompanies maxillary expansion

2. the sutural loosening which occurs during maxillary expansion

Evidences

Baccetti et al (1998) Significant skeletal effects of early treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999). A meta-analysis of the effectiveness of protraction facemask therapy. Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - i.e.: more dental change and less skeletal change.

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

1. fabricate and bond/cement the rapid maxillary expansion appliance

2. Appliance is activated once per day until the desired increase in maxillary width has been obtained.

3. If patients do not need an increase in maxillary width, the appliance is still activated for 7-10 days to disrupt the maxillary sutural system (Haas, 1965)

4. then protraction headgear is fitted.

5. A heavy orthopaedic force of 400g per side is applied to the maxillary complex

6. Force vector should be 15-30 degree below the horizontal

7. The patient wears the facial mask for at least 12-14 hours per day

8. Active treatment should be limited to 9-12 months because of the risk of decalcification of the dentition

9. Retention with a number of appliances: acrylic maxillary retainer, FR-3 appliance or a chin cup (seldom used).

10. Patient should be warned of the possibility of orthognathic treatment if growth is unfavorable

11. Labial root torque: Most class 3 patients demonstrate considerable proclination of the upper labial segment at the end of treatment.. Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination.

The idea of this appliance is that because the condyle is a growth site, the growth impeded by extra-oral force (Graber, 1977).

Despite success in animal experiments, most human studies have found little difference in mandibular dimensions between treated and untreated subjects (Sugawara et al, 1990) . Chincup appliances greatly improve the skeletal profile in the short term such changes are however rarely maintained during the pubertal growth spurt

Force 500g per side 12-14 h/day

Best patient for Chincup therapy. Ko et al (2004)

1. Mild Sk III, ability to achieve edge to edge incisors

2. Short vert face ht (.Chincups cause clockwise rotation of the mandible.

3. proclined or upright LLS (Chincups cause lingual tipping of the lower incisors (Thilander 1963) )

4. absence of severe facial and dental asymmetry

The effects of chincup therapy have been reported as:

1. redirection of mandibular growth vertically

2. retardation of mandibular growth

3. remodeling of the mandible with closure of the gonial angle

4. retardation of downward growth and reinforcement of forward growth in the maxilla

1. Van Beek H. – Combination Headgear-Activator – JCO, March 1984.

2. Van Beek H. – Overjet Correction by a Combined Headgear and Activator – EJO,4(1982) 279-290.

3. Orton H.S. – Functional Appliances in Orthodontic Treatment – An atlas of clinical prescrption and laboratory construction – Quintessence Books, 1990.

4. Skeletal effects of early treatment of Class III malocclusions with maxillary expansion and face-mask therapy Baccetti T et al (1998) AJODO 113: 333 – 343

5. The early management of Class III malocclusions using protraction headgear Marcey-Dare LV (2000) Dental Update 27(10): 508-13

6. Biomechanical and clinical considerations of a modified protraction headgear Nanda R (1980) AJO 78: 125 –139

7. The management of Class III and Class III tendency malocclusions using headgear to the mandibular dentition Orton HS (1983) BJO 10: 2 – 12

8. A philosophy of combined orthopedic-orthodontic treatment PfeifferJP & Grobety D (1982) AJO 81: 185 –201

9. Protraction of the cleft maxilla Ranta R (1988) EJO 10: 215 – 222

10. Bioprogressive therapy Ricketts et al (1979) Section 1 Part 5:Orthopaedics in Bioprogressive therapy and Section 7 Part 7: Factors in headgear design and application

11. Chin cup therapy for mandibular prognathism Graber LW (1977) AJO 72: 23 – 41.

12. The management of Class III and Class III tendency malocclusions using headgear to the mandibular dentition Orton HS (1983) BJO 10: 2 – 12.

13. Effects of chin cup force on the timing and amount of mandibular growth associated with Class III malocclusion Mitani et al (1986) AJO 90: 454 – 463.

14. Stability of changes associated with chin cup therapy Deguchi et al (1996) Angle O 66: 139 – 145.

15. A Randomised linical Trial, Tulloch JFC, Phillips C, Koch and Proffit WR. AJODO 1997; 111: 391-400

16. BOS advices, http://www.bos.org.uk/OneStopCMS/Core/CrawlerResourceServer.aspx

17. Contemporary orthodontics, Fourth Edition, 2007

18. VLE, National orthodontic Program

19. Excellence in Orthodontics

20. Postgraduate notes in orthodontics, 5th edition