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Functional appliances almuzian Functional appliances almuzian Document Transcript

  • Functional Orthodontic Appliances/Growth Modification Appliance/Myofunctional Appliance Mohammed Almuzian 2013
  • Mohammed Almuzian, 2013 1 List of the contents Table of Contents Definition................................................................................................................................................3 History ....................................................................................................................................................3 Classification ..........................................................................................................................................3 I. According to mode of action.......................................................................................................3 II. According to mode of retention ..................................................................................................4 III. Hunt’s Classification...............................................................................................................4 Indications...............................................................................................................................................4 Problems with functional appliances ......................................................................................................6 1. Rebound of overjet..........................................................................................................................6 Aetiology ................................................................................................................................................6 Solutions .................................................................................................................................................6 2. Incisor proclination.........................................................................................................................8 Studies.....................................................................................................................................................8 Solutions .................................................................................................................................................8 3. Lateral open bite .............................................................................................................................9 Compliance with different type of functional appliance.......................................................................10 Problems with functional appliance studies..........................................................................................10 Effects and Mode of action...................................................................................................................11 Dentoalveolar modification..................................................................................................................11 Skeletal effect .......................................................................................................................................12 Soft tissue effect ...................................................................................................................................15 Habit breaker........................................................................................................................................16 Comparing the functional appliance regarding the skeletal effect........................................................16 If there are no skeletal changes by functional appliance, so, why the functional appliance is still recommended highly in growing patient? And what is the factor influencing the timing of treatment with myofunctional appliances ...........................................................................................17 Factor influencing the Choice of appliance of myofunctional appliances............................................21 Types of myofunctional appliances ......................................................................................................21 I. Myofunctional appliances for treatment of Deep overbite ...........................................................21 II. Myofunctional appliances for treatment of openbite ....................................................................22 III. Myofunctional appliances for treatment of Class III ................................................................22 Frankel FR3 ..........................................................................................................................................22 Class 3 twin-blocks...............................................................................................................................22
  • Mohammed Almuzian, 2013 2 IV. Myofunctional appliances for treatment of Class II..................................................................23 a. History of TB................................................................................................................................38 b. Indications of TB ..........................................................................................................................38 c. Advantage of TB...........................................................................................................................38 d. Disadvantage of TB ......................................................................................................................39 e. Design...........................................................................................................................................39 f. Advancement ................................................................................................................................44 g. Clinical tips...................................................................................................................................44 h. Effectiveness of the Twin-block appliance compared to normal..................................................45 i. Profile changes:.............................................................................................................................45 j. Psychosocial benefits of early orthodontic treatment with the Twin-block appliance .................45 FAQ about functional appliance ...........................................................................................................45 I. Treatment duration................................................................................................................45 II. Advantages of two stage treatment with the functional appliance........................................46 III. Advantages of one stage treatment with the functional appliance....................................46 IV. Stability of myofunctional appliances results ................................................................ 47 V. SAQs.....................................................................................................................................47 Mouthguard advice by BOS ..................................................................... Error! Bookmark not defined. Definition................................................................................................. Error! Bookmark not defined. Prevalence of trauma ............................................................................... Error! Bookmark not defined. Materials .................................................................................................. Error! Bookmark not defined. Types of mouthguard............................................................................... Error! Bookmark not defined. 
  • Mohammed Almuzian, 2013 3 Functional Orthodontic Appliances/Intraoral Growth Modification Appliance/Myofunctional Appliance Definition A removable or fixed orthodontic appliance which use or eliminate the force arising from the masticatory, facial muscles & peridodontium to alter the skeletal and dental relationship. (Mills, 1991).The term “myofunctional appliance” is preferable as they all depend for their action upon the activity of the orofacial musculature. History  Kingsley in 1879 used the bite jumping appliance.  Inclined bite plane first used in 19th century In Spain by Catalan.  Monobloc appliance developed 1902 Pier Robin  Andreasen appliance (activators), developed from URA retainers used with inclined bite planes and mandibular lingual extensions when Andreasen prescribed it to his daughter during her long school holidays in Norway. (Andreasen and Haupl,1936)  Balter Bionator 1950  Frankle appliances 1966  TB appliances were originally described by William Clark (1982 and 1988). Classification I. According to mode of action by Vig and Vig 1974. 1. Myotonic: Work by passive muscle stretch through large mandibular opening (8-10mm). eg. Harvold 2. Myodynamic: Work by stimulation of the muscle activity with medium mandibular opening (<5mm). eg Andreasen, Bionator, MOA
  • Mohammed Almuzian, 2013 4 II. According to mode of retention 1. Tooth borne:  Passive tooth borne eg Andreasen, Bionator  Active tooth borne eg twin block, Herbst. 2. Tissue borne eg Frankel III. Hunt’s Classification 1. Removable: good for deep overbite / short face cases. Andreasen, Bionator, Harvold, MOA, Function Regulator. 2. Removable functional headgear appliances: good choice in high angle cases, CTB (Clark, 1982) with HG, Van Beek, Bass appliance with HG, Teuscher or headgear activator Teuscher appliance (HATA) 3. Fixed: can be classified as either A. Flexible (Flexible Fixed Functional Appliance – FFFA) AdvanSync B. Rigid (Rigid Fixed Functional Appliance – RFFA) Dynamax C. Hybrid types- Herbst (Pancherz) Indications 1. Interceptive treatment for trauma: Functional appliances are frequently advocated for early treatment to reduce the overjet early which subsequently might reduce trauma. This had been disapproved by (Kurlock 2004) 2. Psychological advantages in young patient: Functional appliances are frequently advocated for early treatment to reduce the overjet early which subsequently might reduce teasing problems. (O’Brien 2003)
  • Mohammed Almuzian, 2013 5 3. Orthopaedic treatment  Correction of AP in class II division 1 malocclusions or class II D2 with incisors decompensation (for more details see below)  CL III cases.  AOB like Frankle 4  Mild degree of facial asymmetry by using hybrid appliance 4. Compromise treatment: Some cases are not suitable for fixed appliance treatment because of, for example, poor oral hygiene, so the functional appliance can offer an acceptable degree of occlusal and facial improvement. 5. Anchorage reinforcement: Turning a class II case into an easy class 1 case 6. Habit breaker (digit sucking) combined with one of the above problems. Correction of AP in class II division 1 malocclusions or class II D2 with functional appliances 'Classic' functional appliance cases is: 1. Growing patient 2. Motivated patient 3. Moderate to severe Class II D1 or class II D2 with incisors decompensation 4. Normal or low MMPA (average or increased OB) 5. Slightly proclined upper teeth. 6. Slightly retroclined lower incisors. 7. Well aligned or minimal crowded arches. Class II cases not suitable for functional appliances 1. Non-growing patient 2. High angled cases, posterior mandibular rotation, AOB 3. Cases with proclined LLS or retroclined ULS
  • Mohammed Almuzian, 2013 6 4. Cases which can be treated by conventional fixed appliance on extraction or non-extraction basis. Problems with functional appliances 1. Rebound of overjet 2. Lower incisor proclination 3. Lateral open bite In details 1. Rebound of overjet Aetiology I. A rebound of condylar position caused by atrophy of hyperatrphyed meniscus II. Reduction in the activity of protractor muscle (lateral Pterygoid muscle) III. Uprighting of ULS or LLS. LLS relapsed more. IV. Unfavourable growth Solutions (DiBiase and Fleming 2007) wrote a comprehensive review article about this topic. They mentioned the following as a transition technique: Technique Advantages Disadvantages 1. Over-correction. To counteract the relapse 2. Reinforcing anchorage Headgear and palatal arches To control molar buccal tipping during alignment stage. 3. Maintaining postured bite by inclined URA or clip over URA (Plint clasp appliance). The bite plane should be 8mm deep and 70 degree inclination (Sandler and DiBiase, 1996).  Maintain transverse correction  Allow settling of occlusion  Maintain class II effect.  Increased proclination of LLS.  Interference with the placement of FA. 4. Night wear appliance. Advantages:  Better to predict rebound,
  • Mohammed Almuzian, 2013 7  Good time for postured condyle to adapt  Good settling of occlusion,  Maintain transverse correction 5. Integration of the functional appliance with the fixed appliance until rigid AW in place.  Good settling of occlusion,  Maintain transverse correction  Quick methods But this needs a modification in the functional appliance to avoid interference with FA. 6. Early light class II elastics at an early stage on light wires to keep overjet controlled.  Further proclination of LLS and retroclination of ULS.  Extrusion of LBS cause reduction in the OB  Lingual tipping and rolling of the lower molars due to poor rigidity of the NiTi AW. 7. Appliance prescription (MBT is preferred because  It correct LLS and ULS inclination  The zero tipping of the U6 and U3 cause less rebounding effect  Increase palatal root torque of buccal segment will compensate for tipped molar due to expansion.  Lastly the reduce lingual crown torque of L6 to counteract the lingual rolling when class II elastic is used 8. The use of fixed functional appliance to avoid the transitional phase Dynamax Fixed TB AdvanSync Herbst 9. Last option is the immediate transition without retainer. It is a short treatment option Difficult to predict rebound, No time for postured condyle to adapt No settling of occlusion
  • Mohammed Almuzian, 2013 8 2. Increase in the incisor inclination (upper retroclination and lower proclination) Lower incisor proclination is a feature of almost all functional appliance treatment. (Approximately 8-15 degree) Studies Studies show a wide range of proclination with any given appliance and a wider range between different appliances. • Appliances which are tooth-borne, such as the Herbst appliance, seem to produce greater proclination (average 3.2 mm or 11 degrees in Koutsonas and Pancherz, 1997). • The Bass appliance which places no direct pressure behind the lower incisors can produce very little labial incisor movement, albeit with slower overjet reduction. Bass 2006 • Lund and Sandler (1998), reported average proclination of 8+7 degrees using TB. Solutions 1. Lower labial cap of acrylic on their twin blocks and reported average proclination of 5.2+3.9 degrees (Young & Harrisson 2005). However this might cause extensive decalcification in poor OH (Dixon 2005). 2. Trenouth & Desmond (2010) used Southern end clasps on the lower incisors and reported almost no lower incisor proclination. 3. Other functional appliance like Dynamax 4. Headgear with functional appliance 5. Relief to the acrylic lingual to the lower incisors (Ball and Hunt, 1991) 6. Avoidance of labial bows in the upper arch
  • Mohammed Almuzian, 2013 9 7. Extending the lower lingual acrylic as posterior as possible 8. Incremental advancement 9. Short time use or avoidance of class II elastic 10.Overcorrect the OJ and then use class III elastic 11.MBT prescription 12.Extraction 3. Lateral open bite 1. Lower incisor capping to prevent incisor overeruption. 2. Upper incisor capping or 'torquing' spurs to prevent incisor overeruption. 3. Grinding from the functional appliance to allow eruption. However this might encourage the lower molars to erupt more mesially causing lower premolar crowding as well as leading to more LLS crowding. 4. Night time wear. However it is important to mention that one intriguing thought arises from work showing by Lee and Proffit (1995), that nearly all human tooth eruption occurs between 8 pm and midnight. Should we get our patients to wear the twin block just in the mornings once the overjet is reduced and the remaining posterior open bite can usefully settle at night when teeth erupt? 5. Stop and wait until settling of the occlusion 6. Steep and deep URA. 7. Other type of removable functional like Dynamax. 8. Claim that fixed functional produce less open bite problems 9. Fixed appliance
  • Mohammed Almuzian, 2013 10 Compliance with different type of functional appliance In general the TB fail in 1 out of 5 patients Failure rate TB in pre-adolescent 18% O’Brien 2003 TB in adolescent 25% 33% 9% O’Brien 2003 b (with herbest) Lee et a 2007 Incremental and one go advancement TB The first one has half of the failure of the latter Bank 2004 Fixed TB 3% Read, 2001 Dynamx 9% Lee et a 2007 Dynamx 84% Bader Thiruvenkatachari, 2010 Herbst appliance 13% O’Brien 2003 Frankle appliance 42% in female and 24% in male Ghafari 1998 HG 5% for female and 25% for male Ghafari 1998 Problems with functional appliance studies 1. Small samples 2. No controls:  No controlling to differentiate treatment effect from normal growth effect.  If involved historic control it is considered invalid for the today population  Also the randomization is absent which would not involve the bias in the confounding factors. 3. Retrospective so the best cases tend to be selected. 4. Unmatched samples for age and gender 5. Different appliances 6. Different operators 7. Different lengths of study
  • Mohammed Almuzian, 2013 11 8. Inaccuracies in measurement 9. Most based on cephalometric. 10.Animal studies may not be relevant to humans. This is because:  Animal are different species  Animal has no class II problems  Unrealistic prolong use of functional in animal On the other hand, the retrospective are weak studies because:  Only good cases were shown  Only enthusiastic clinician are involved So the RCT are the gold standard Mode of action  Stretch and activate the muscle of mastication and facial muscle  Stretching of periosteal  Relieve soft tissue effect (Frankle appliance)  Disocclude the occlusion Effects Effect With Against Dentoalveolar modification We should employ the knowledge that a large proportion of their effect is via upper incisor retroclination and distal movement of upper molars 1. ULS retroclined 2. LLS proclined 3. Distalization of U molars. 4. Mesilaization of L molar 5. Inhibition of the eruption of upper posterior teeth
  • Mohammed Almuzian, 2013 12 6. OB: Differential eruption of the teeth by encouragement of the eruption of lower posterior teeth which cause reduction in the OB and increase LAFH. 7. Transverse expansion if screw is incorporated The evidences are: 1. Tulloch et al 1997 2. Tulloch et al 1998 3. Lund and Sandler 1998 4. Keeling et al 1998 5. Ghafari 1998 6. O’Brien et al 2003 7. Dolce et al 2007 8. O’Brien in 2009 These dental effects are due to the stretching of the muscle of mastication and facial tissue as well as alteration of the soft tissue balance when the mandible is postured. Skeletal effect Effect With Against Redirection of condylar growth (altering growth direction, mainly vertically) which is more stable over a long period of time Mills, 1991 Condylar position changes within the fossa results mainly due to condyle remodelling and glenoid fossa remodelling Petrovic 1990 suggested that the functional would increase the activity of the lateral pterygoid which helps in enhancing growth of the An MRI study by Ruf and Pancherz (1998) showed no mean change in condylar position within the fossa
  • Mohammed Almuzian, 2013 13 condyle by increasing the number of proliferative cells. Mandibular effect: Enhancement of mandibular growth (True condylar growth). It is probable that an average 1-2 mm of extra short-term mandibular growth can be obtained. There is a great individual variation regarding this issue. This is clinically worthwhile, but it would not be sufficient to obviate orthognathic surgery in those cases deemed to require it before the start of treatment. The increasing evidence is that the long-term gain in mandibular growth is very small or non-existent. Animal Studies, McNamara 1987 showed that the mandible of monkeys grow by 5-6mm more than control. Human Studies on long term 1. Weislander (1993) showed 2mm skeletal changes lost after 2 years 2. Keeling et al (1998), Bionator, one year after active treatment, all changes lost. 3. The long-term results of the groups in the RCT by Keeling et al have been published (Dolce et al 2007) and they show no long-term differences 4. Tulloch et al (1997) using Bionator showed a small (0.6 degrees/year) enhancement of mandibular growth in the short term, then Tulloch et al (1998) Human Studies on long term, Lund and Sandler (1998) they found cephalometric evidences of mandibular growth when measured as Articulare-Pogonion but could not attribute this growth or just repositioning.
  • Mohammed Almuzian, 2013 14 none in the after 1 year 5. Tulloch et al (2004) the growth modification group were lost. 6. O’Brien et al (2003) using TB, growth in the mandible of approximately1.2 mm per year. This small change was stable 12 months after treatment. 7. O’Brien in 2009 long-term results there were no differences of skeletal pattern 8. Harrsion 2007 Maxillary skeletal changes: Restriction of the maxillary growth. An average 1-2 mm of long-term maxillary restraint seems possible, although many studies fail to find this. There is some evidence that this does not on long term,  The study by Weislander (1993) showed that maxillary growth restraint actually increased relative to controls after No significant maxillary restraint, with Frankel appliance Keeling et al (1998) or with the modified Bionator (Tulloch 2004).
  • Mohammed Almuzian, 2013 15 relapse after active treatment, but may continue and even increase. the end of active treatment using a combined Herbest-HG appliance.  O’Brien et al (2003) found 0.88mm restraint in the TB gp. 3. Soft tissue effect 1. Muscles of face: Frankel reported to restrain the muscles of face 2. Muscle of mastication: Other appliances stretching the muscle of mastication specially lateral pterygoid. So the force will be transmitted to the dentition causing a dentoalveolar changes, condylar adaptation and growth 3. Tongue: functional appliance can remove tongue adaptively. 4. Lip muscle: Functional appliance can eliminate lip trapping which is a cause of proclination All these effect produce dental and skeletal changes by altering position of balance (Bishara & Ziaja, 1989). The soft tissue changes include: (Sharma and Lee 2003, 2005). 1. Increased commissure width 2. Increased LFH,
  • Mohammed Almuzian, 2013 16 3. Retrudes the upper lip. 4. Increased lower lip height & projection, 5. Increased projection of ST pog 4. Habit breaker: By occupying the space which might be a space for the digit and or tongue in case of habit. NB: Summary of the evidences:  The increasing evidence is that the long-term gain in mandibular growth is very small or non-existent. It is probable that an average 1-2 mm. of extra short-term mandibular growth can be obtained. This is clinically worthwhile, but it would not be sufficient to obviate orthognathic surgery in those cases deemed to require it before the start of treatment.  An average 1-2 mm of long-term maxillary restraint seems possible, although many studies fail to find this. In contrast to the mandibular effect, there is some evidence that this does not relapse after active treatment, but may continue and even increase. Headgear may well be more effective for maxillary restraint.  We should remember the large variability of growth - both with and without treatment.  Some uncertainty remains about the influence of the pubertal growth spurt on growth enhancement.  We should employ the very large occlusal benefits of functional appliances in the knowledge that a large proportion of their effect is via upper incisor retroclination and distal movement of upper molars. 75% dentoalveolar and 25% short term skeletal changes.  We should keep in mind that the skeletal changes might be relapsed after finishing FA treatment. For example a patient use TB to correct class II D1 malocclusion, in general he will gain a lot of dentoalveolar changes as well as some skeletal changes. According to the evidence the skeletal changes will lost in average two years after functional treatment. So this is one of the causes of relapse after treatment as well as one of the reasons for continuous use of active retainer in a form of steep and deep or activator. The aims of using it after active treatment are to enhance more dentalveolar compensation when the skeletal changes relapsed. Comparing the functional appliance regarding the skeletal effect
  • Mohammed Almuzian, 2013 17 1. TB versus Bionator by Harrsion 2007 statistic difference in the reduction of ANB when TB compared to bionator, however, there was no difference in regard to the final OJ. 2. Comparison of Herbst with twin-block appliances in preadolescent patients, O’Brien 2009, Treatment with the Herbst appliance resulted in a lower failure- to-complete rate for the functional appliance phase of treatment (12.9%) than did treatment with Twin-block (33.6%). Herbest appliance where more effective in reducing OJ than TB. However, there were no differences in treatment time between appliances, There were no differences in skeletal and dental changes 3. Comparison of Twin-block and Dynamax appliances. ,  Lee et al 2007, similar compliance rate. More breakage with Dynamax. Forward movement of the chin and Pog are similar. More vertical skeletal changes with TB (6mm compared to 5mm), ANB changes in TB 2 degree and in Dynamax 1 degree.  Thiruvenkatachari Bader, 2010, The incidence of adverse events was greater in the Dynamax group (82%) than in the Twin-block group (16%). The Twin- block appliance was more effective than the Dynamax appliance Factor influencing the timing of treatment with myo-functional appliances  Dental factors  Growth spurt  Trauma prevention  Psychological factors  Patient compliance Factors With Against Dental factors Better to start when the
  • Mohammed Almuzian, 2013 18 permanent teeth have erupted for better clasping of the appliance. Treatment whilst deciduous teeth are being shed may pose minor problems of appliance retention, discomfort or a delay in the shedding of deciduous teeth. Growth spurt The principle issue to start functional appliance is to try to synchronize the treatment with pubertal growth spurt. Treatment during growth spurt may cause slight difference from that earlier or later in that it has little dental tipping, more skeletal growth and stable results as well as better occlusal settling. Pancherz (1985) and Baccetti (2000). Stephens and Houston (1985) stated that a growing patient has greater potential for:  Dentoalveolar effect of the functional appliance  Overbite reduction  Occlusal settling  Space closure  Maxillary expansion  Distalization or mesialization of posterior teeth. All of these make changes by functional appliance as well as But neither Tulloch 1997 using hand wrist or O’Brien 2003 using CVM failed to relate the skeletal changes to skeletal maturity. An important point is that the growth spurt cannot be predicted with clinically useful accuracy. Even with longitudinal monitoring of stature, Sullivan (1983) has shown that our prediction will still be more than one year incorrect in 33% of cases.
  • Mohammed Almuzian, 2013 19 the second phase fixed appliance efficiently and fast. Trauma prevention A definite potential advantage of starting treatment early is the reduced incidence of trauma to prominent upper incisors. High trauma with increased overjets >9mm (Todd & Dodd 1983) (45% 10 yr olds with OJ more than 9mm have traumatised incisors compared to 27% if the OJ was less than 9mm especially if the lip is incompetent. However this had be contradicted by Korluk in 2004.The same results by O’Brien 2009. But the latest Cochrane review by Thiruvenkatachari in 2013 confirm the trauma prevention benefits of early treatment. Psychological factors Unless for psychosocial reasons (increase self-concept, reduce negative experience and improve self esteem) (O’Brien 2003), which can result from teasing, early treatment with functional appliances is not indicated. Patient compliance The studies by O’Brien et al (2003) showed a significantly lower failure-to-finish rate in the
  • Mohammed Almuzian, 2013 20 younger patients when treated by the same operator with the same appliance. Similarly, the study by Banks et al (2004), found that patients younger than 12.3 years were three times more likely to complete functional treatment with twin-blocks. Summary 1. Dental factors are important. We usually want to start treatment as soon as the eruption of the permanent teeth permits and this is in the late mixed dentition. 2. Enhancement of growth is on average small and seems to be only marginally related to the pubertal growth spurt. However, it is probable that regardless of growth enhancement effect, treatment is faster rapid growth. Treatment during growth spurt is aiming to a. Borrow the potential mandibular growth when needed b. Provide a better environment for dentoalveolar compensation c. Disoccluding the unfavourable occlusion that might interfere with the potential growth leading to dysmorphic compensation (Kim and Nanda 2002, You 2001 using Burlington sample). However there is no evidence comparing adolescent patients with TB treatment to control because of the equipoise. Again the long term effect involve limited AP changes and more attractive profile (O’Brien 2009 a & b) with increase VH, dental and occlusal changes and favourable ST changes for low angle cases. 3. An early treatment in large class 2 discrepancies may be moderately significantly advantageous in terms of dental trauma
  • Mohammed Almuzian, 2013 21 4. An earlier start than this in large class 2 discrepancies may be advantageous in terms of psychosocial benefits 5. Cooperation with functional appliances is better before 12.5 years of age Factor influencing the Choice of appliance of myofunctional appliances 1. Patient factors • Patient compliance • Type of malocclusion • OH • Preference 2. Clinician factors preference • Familiarity • Laboratory facilities • Available evidences Types of myofunctional appliances I. Myofunctional appliances for treatment of Deep overbite 1. The Anterior Bite Plane (ABP) It is the simplest form of a myofunctional appliance. Its types; 1. Upper horizontal bite-planes 2. Upper inclined bite-planes 3. A lower inclined bite-plane can be used in deep bite class III cases.
  • Mohammed Almuzian, 2013 22 II. Myofunctional appliances for treatment of open bite  Frankle IV  Intrusive splint  The oral screen A. Design This very simple functional appliance lies in the labial vestibule. The oral screen has no place in modern orthodontics. B. Indication: 1. It has been used to discourage thumb-sucking and to correct the associated malocclusion. 2. Prevention of trauma during contact sport activity. 3. It has also been used for lip training in patients with incompetent lips. III. Myofunctional appliances for treatment of Class III 1. Frankel FR3 2. Class 3 twin-blocks Frankel FR3 1. Not commonly used 2. Holding away of the soft tissues from the upper incisors would stimulate maxillary growth through stretching the periosteum. 3. Most of the effects are dentoalveolar. Class 3 twin-blocks 1. Not commonly used 2. In this case, the mechanism is a reversal of the conventional orientation of interlocking blocks used to posture the mandible forward in class 2 cases. 3. Most of the effects are dentoalveolar.
  • Mohammed Almuzian, 2013 23 IV. Myofunctional appliances for treatment of Class II 1. Lip bumper 2. The Andresen appliance (or activator) 3. The Bionator 4. Harvold appliance 5. The Palatal and Labial Medium Opening Activators (MOA) 6. The Frankel appliance 7. The Intrusive Myofunctional Appliances 8. Teuscher appliance 9. Hybrid appliance 10.Mini-block appliance 11.Twin-block type appliances 12.Fixed twin block 13.The Herbst appliance 14.The Dynamax appliance 15.The AdvanSync appliance 16.Fixed magnetic appliance In details The Andresen appliance (or activator) The activator was popularized by the publication of Andresen in 1936. It is a loose appliance. A. Mode of action:  It is loosely fitting act as an exercise appliance resulting in passive tension of the muscle and moderately displaces the mandible forwards (passive tooth borne)  Moderately bite opening (Myodynamic) <5mm B. Indications: Useful in mild to moderately severe class II cases with no crowding
  • Mohammed Almuzian, 2013 24 C. Instruction for Use: The patient is instructed to wear the appliance for 10-12 hours in every 24: this will be at night with 2-4 hours' wear in the evening D. Design:  Upper labial bow.  Upper and lower baseplates sealed together.  The acrylic caps the lower incisor edges to prevent them from over erupting  In the upper arch these slope guided the teeth distally and buccally as they erupt with the opposite in the lower arch.  It is possible to reactivate the first appliance by trimming it away from the lower teeth so that wax can be added to register the more advanced position of the mandible. E. Advantage of Andresen over TB (Bennet 2001) 1. Robust 2. Simple and cheap 3. Part time wear cause less dental effect and more skeletal 4. Easy to wear because not complicated and only 2-4mm opening of the bite 5. No lateral OB because eruption is allowable during its use and there is no intrusive force on the post teeth, so less time for transient or supportive stage The Bionator A. History:  Advocated by Balter Bionator 1950.  This appliance is derived from Andresen's activator but is greatly reduced in bulk.
  • Mohammed Almuzian, 2013 25  Although it has generally been neglected outside Germany. B. Mode of action:  Loose appliance (passive tooth borne)  Moderately displaces the mandible forwards & moderately bite opening (Myodynamic) <5mm C. Indication:  Useful in mild to moderately severe class 2 cases with no crowding. D. Instruction for Use:  Worn full time apart from during meals and sports. E. Design Similar to the activator except:  The palatal acrylic coverage is replaced by palatal loop 1.25mm to encourage a forward posture of the tongue and mandible.  Upper posterior teeth occlusal coverage while the lower are free to erupt except the LLS which are capped.  The vestibular bow 0.9mm contacts the upper incisors but is clear of the buccal teeth by 2-3 mm to allow expansion. F. Evidences  The study by Tulloch et al 1997 (class II D1 OJ 7mm, HG, Bionator or CG for 15 months) concluded that the bionator produced some mandibular change, whereas, with the headgear, there was some maxillary restraint. In the TG (HG or Bionator) the improvement in the ANB in 70-80% while no improvement in 20%. In the CG no improvement 50%, improvement 30% and worsening 20%.  Then Tulloch 1998 followed the patient and found that skeletal improvement is lost after 1 year.  Keeling et al 1998 (HG/Biteplane, Bionator, CG, OJ 7mm for 2 years or until class I achieved) suggested that a headgear biteplane combination resulted in no
  • Mohammed Almuzian, 2013 26 restraint of the maxilla but forward positioning of the mandible while bionator resulted in some mandibular growth that lost after 1 year follow up. Harvold appliance A. History: The Harvold appliance is derived from the activator of Andresen. It is similar to MOA except the amount of opening is more. B. Mode of action:  Loose appliance (passive tooth borne)  The mandible is advanced a few millimetres less than the maximum the patient can achieve.  It is opened to give an interocclusal clearance of 10-20 mm measured at the premolars. This is a myotonic appliance C. Indication: Useful in mild to moderately severe class 2 cases with no crowding and deep anterior bite due to deep COS. D. Instruction for Use: 24h except meal time E. Design:  The upper labial bow  Upper occlusal coverage  Adam on U6 and U4  Lower incisor capping Medium Opening Activators (MOA) A. Mode of action:  Loose appliance (passive tooth borne)  Moderately displaces the mandible forwards
  • Mohammed Almuzian, 2013 27  Moderately bite opening (Myodynamic) <5mm Indication: Useful in mild to moderately severe class 2 cases with no crowding and deep anterior bite due to deep COS. B. Instruction for Use: 24h except meal time. C. Design:  The upper labial bow  Upper occlusal coverage  There are Adams cribs and occlusal rests present on the upper first permanent molars and first premolars.  Lower incisor capping The Frankel appliance A. History : This appliance, named after its originator, Rolf Frankel of East Germany, B. One of its advatages is using it in a mixed dentition. C. Mode of action &Design:  It is a myodynamic loose tissue born appliance, so it activate the lateral pterygoid muscle.  Frankel termed it a function regulator (FR) because it is intended to correct functional anomalies in the circumoral musculature, which he holds responsible for crowding and other aspects of malocclusion  The buccal shields extend to produces 'periosteal stretch ‘and the teeth are free of muscular pressures on the buccal but not on the lingual surfaces.  The lip pads (Pelotte wire) are also intended to a. Produce periosteal stretch
  • Mohammed Almuzian, 2013 28 b. Alter and control lower lip activity, c. The lip pads eliminate any trapping of the lower lip behind the upper incisors. d. When the lip is displaced by the lip pad, it will force the appliance posteriorly causing some headgear effect.  The lingual pad contacts the alveolar mucosa on the lingual surface of the mandibular alveolar process, but it is clear of the teeth. Thus a forward mandibular posture is induced without any protrusive force on the lower incisors. D. Indication 1. Frankel 1a – Class 1 2. Frankel 1b – Mild Class 2/1 3. Frankel 1c – Moderate Class 2/1 4. Frankel 2 – Class 2/2 5. Frankel 3 – Class 3 6. Frankel 4 - AOB E. Instruction for Use: the patient should wear it full time, except for meals and sport  The study by Ghafari et al 1998 suggested that headgear produces some maxillary restraint and the Fränkel, mandibular growth increase. Hybrid functional  Used in the orthopaedic management of occlusal canting in growing patients (Vig and Vig 1986).  It consists of acrylic block at the side of overgrowth and no block at the undergrowth site to allow differential eruption of the teeth at the underdeveloped site.  There is a buccal shield same like the one use in Frankle appliance to allow arch expansion.
  • Mohammed Almuzian, 2013 29 Lip bumper A. Design:  This is a functional component, occasionally used in conjunction with a lower fixed appliance. B. Indication:  The lip bumper can occasionally be useful in Class 11, division 1 with lip trap interference.  Distalization of lower molars  Reinforce lower posterior teeth  IO to avoid loss of space after premature loss of primary teeth. C. Mode of action  Change in muscle balance  Periosteal stretching. The Dynamax appliance Advantages 1. Little patient compliant. 2. No need for a postured bite 3. Incremental mandibular advancement. 4. It can be used with fixed appliance. 5. Minimal mouth opening - which may increase patient acceptance, especially in high angle cases with less (the 'goldfish' look). 6. Upper incisor inclination is controlled by torque spring 7. Extra oral traction may be added.
  • Mohammed Almuzian, 2013 30 8. Conversely, the posterior occlusal capping helps control molar eruption in cases with reduced overbite. The aims of the post capping are to  Disoccluding the teeth,  Allow even distribution of the HG force  Prevent and intrude U post teeth. 9. Dynamx show better control of vertical height and insignificant less relapse than TB (Lee 2007) 10.Little LLS proclination because the appliance works by avoidance's reflex theory which might cause little LLS proclination.(Myodynamic passive tooth borne appliance). Disadvantages  It has higher failure rate than TB (two times more failure rate). Thiruvenkatachari, 2010.  As well as more difficult to construct. The Herbst appliance A. History: It was first described by Dr. Herbst and popularized by Pancherz 1979. B. Design:  Fixed functional.  Bands on upper and lower 6’s and 4’s.  Palatal bar and lingual bar.  Telescopic arms form upper 6’s to lower 4’s. C. Advantages According to O'Brien study in 2009, Herbst was superior to Twin Block when we measured:
  • Mohammed Almuzian, 2013 31  Speech interference.  Disturbance of sleep.  Influencing school work.  Feelings of embarrassment.  Better success rate than Twin Block.  It can be used with fixed appliance. Recently a Flip-Lock Herbst assembly with the 'male' attachments welded to rectangular tubing, which is slid over a rectangular archwire. This mechanism is very simple to install and to date is encouragingly robust. D. Disadvantages 1. Expensive. 2. Breaks more significant and mechanical failure of piston assemblies. 3. Cement problem. 4. Removal difficulty. 5. Enamel decalcification. 6. Recommended in the permanent dentition only 7. If joined with FA treatment, it should use when full arch SS in use. 8. Inability to incorporate arch expansion during the functional phase 9. Do not grow mandibles and in contrast to others, there is evidence of sufficient satisfaction with other simpler functional - in particular the twin- block. 10.More lower incisor proclination E. Indications
  • Mohammed Almuzian, 2013 32 a. Dental Class II malocclusion. b. Skeletal Class II mandibular deficiency. c. Deep bite with retroclined mandibular incisors. d. Pancherz (1995) also recommends its use in post-adolescent patients, mouth- breathers, uncooperative patients, and those that do not respond to removable functional appliances F. Contra-indications a. Cases predisposed to root resorption. b. Dental and skeletal open bites. c. Vertical growth with high maxillomandibular plane angle and excess lower facial height. G. Effects of the Herbst Appliance 1. Restraining effect on maxillary growth 2. A stimulating effect on mandibular growth. The long-term effect on mandibular growth is uncertain and may only have a short-term effect on skeletal growth pattern (Pancherz and Fackel, 1990). 3. Dento-alveolar changes include lower incisor proclination, upper incisor retroclination, lower posterior teeth mesialization and maxillary molar
  • Mohammed Almuzian, 2013 33 distalization and intrustion. The changes are similar to those produced by high pull headgear (Pancherz and Anehus-Pancherz, 1993). 4. Vertically, the overbite is reduced. This occurs by intrusion of lower incisors and enhanced eruption of lower molars (Pancherz, 1995) 5. Hansen et al. (1990) found that the appliance did not have any adverse effects on the temporomandibular joint (TMJ). The AdvanSync appliance A. History: Developed by Terry Dischinger in 2008 B. Design:  This molar-to-molar fixed functional assembly  The name of the appliance therefore reflects that the mandible can be postured forward synchronously with the start of all the other fixed appliance tooth movements.  The appliance requires no laboratory work  Molar band separation at one visit permits selection and cementation of the molar attachments at the next visit.  The telescoping arms have a long range of action and permit good lateral excursion and are very easily advanced either by means of the alternative screw position on the lower molars or via C rings which are crimped over the pistons. The Intrusive Myofunctional Appliances As Tulloch points out, there is a widespread belief that children who grow vertically will respond less well to class 2 treatment, but this is not well documented or understood. The study by Ruf and Pancherz (1997) found no
  • Mohammed Almuzian, 2013 34 evidence to support this view. The “hyperdivergent” cases in fact showed 1 mm. better mandibular response than the “hypodivergent” cases although this was not statistically significant. This evidence suggests that ‘high angle’ cases are no reason to avoid functional appliances because of the potential effects on growth. These appliances will be discussed below: 1. The 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 near the area of maxillary rotation (premolar area).  There is a midline screw present in the palatal acrylic.  This appliance is used to treat skeletal anterior open bites by intrusion of the upper buccal segment teeth. 2. The Maxillary Intrusion Splint (MIS) • This appliance consists of an acrylic baseplate which extends over the occlusal surfaces of all teeth and onto the incisal surfaces of the upper anterior teeth. • There are Adams cribs present on the upper first permanent molars and first premolars, along with a Southend clasp on the upper central incisors. • There are headgear tubes present within the molar capping • This appliance is designed to be used for patients with a Class II division 1 malocclusion and a "gummy smile" with an overjet of 6 to 8mm. . 3. The Maxillary Intrusion Splint and Lower Traction Plate (CONCORDE)
  • Mohammed Almuzian, 2013 35 • This is a two part appliance which consists of a maxillary intrusion splint as described above along with a lower appliance. • The lower appliance consists of an acrylic baseplate with no occlusal or incisor capping. There are double Adams cribs present on the lower first permanent molars and second premolars, and a semi-fitted labial bow on the lower incisors. • There is a lingual hook on the lingual aspect of the acrylic baseplate to enable elastics to be attached to the midpoint of the facebow. • The selection criteria are the same as for the maxillary intrusion splint but these combined appliances work more effectively at reducing overjet between 9 to 18mm than the maxillary intrusion splint alone. • This appliance combination can also be used for the treatment of a severe Class II division 1 malocclusion with a "gummy smile" and an average face height. 4. The Intrusive Activator a. The Van Beek appliance  Described by Pfeiffer (1972).  It consists of a simplified short outer arm facebow embedded in the acrylic part of the activator (Myotonic functional appliance)  There is full palatal coverage and fully extended lingual flanges  There is no buccal channel  300 gms of force/12 hours a day b. Teuscher appliance
  • Mohammed Almuzian, 2013 36  Teuscher (1978)  Basically it is an activator with two significant design features - torquing spurs on the upper incisors to prevent retroclination and headgear to produce more vertical control and anterior restraint on the maxilla  There advancement of 6mm maximum and minimal bite opening  Indicated in high angle class II D1 Newport appliance: same as TB A fixed magnetic appliance  Described by McNamara 1998,  This appliance presents a promising mode of improving facial harmony in patients with Class II, Division 1 malocclusion associated with mandibular retrusion, increased lower facial height, and increased interlabial gap.  Further research and development of the appliance are advocated.  It is useful in high angle case as the condyle is displaced inferiorly resulting in increase in the PFH and improving of the MMPA angle.  A fixed magnetic appliance was designed that hinged the mandible open and exerted an intrusive force on the teeth. Treatment with this appliance resulted in: 1. An increase in length of the mandible 2. Intrusion of teeth 3. Upward and forward autorotation of the mandible 4. Creation of temporary buccal crossbite caused by the shearing force of repelling magnets Miniblock appliance A. Design:
  • Mohammed Almuzian, 2013 37 Same as TB but with 1. Reduced height of block with 90 degree angulation of the step. 2. Gradual advancement 3mm 3. Incisor torque spurs. B. Advantages: 1. The idea is that gradual advancement will activate lateral pterygoid muscle, this will achieve better growth. 2. The reduced the visco-elastic force on the teeth by gradual advancement will cause less teeth inclination. 3. Reduction in the block height will cause the reactive force vector to pass close to the centre of resistance of maxilla so it cause less rotation of maxillary plane and then less increase in the facial height. 4. The benefit of the incisor torque spur is controlling of incisor inclination C. Evidences  Two reports of a RCT study (Shrarme and Le, 2002, Gill & Lee 2002) compared the hard and soft tissue effects of a conventional twin-block with a single large advancement and a modified twin-block named the Mini block. The only differences of significance were that the conventional Twin-block retroclined the upper incisors a little more and advanced hard and soft tissue Pogonion approximately 2mm more on average. Lower incisor proclination was very similar. Fixed twin block A. History: Developed by Mike Read (2001). B. Advantages  Robustness and possibly patient comfort  Because the two halves of the appliance are not permanently linked together, the problems of leverage on the fixation points does not arise during mandibular excursion in contrast to Herbest appliance.
  • Mohammed Almuzian, 2013 38  Integration of FA is easy from the start  No lateral open bite. C. Disadvantages • OH problems and decalcification • Need for lower premolar bands to remain securely cemented. • Not quick and easy for all clinicians to make, fit and adjust as well as robustness. • Need technical development and extra experience are continually bringing improvements. Twin-block appliances a. History of TB • These appliances were originally described by William Clark (1982). • Survey in UK by Chadwick 1998, 75% of orthodontist are using TB. b. Indications of TB 1. Cooperative 2. Good OH 3. Class 2 with deep OB with minimal dental compensation 4. Growing patient. Recent prospective studies have found that stage of maturity of the cervical spine did not influence outcome, O’Brien 2003. The same result by Trenouth and Desmond 2012 who showed that there is no correlation between the age and the skeletal effect of TB. c. Advantage of TB Harradine and Gale (2000) and Morris et al. (1998)
  • Mohammed Almuzian, 2013 39 1. Robust 2. Easy to repair 3. Easy to activate. 4. Relatively well tolerated by the patient because it is two pieces that is not interfering with function. 5. Expansion is easy by a midline screw 6. Incorporation of auxiliary and headgear is easy. 7. Suitable for mixed or permanent dentition. d. Disadvantage of TB 1. Require skilled technician 2. Failure rate of 33% (O’Brien) 3. Poor retention of LRA because of shallow inter-proximal dental undercut in a younger age group. 4. AP change too rapid: This would result in posterior open bites. 5. Teeth tilt excessively: lower incisor proclination and upper incisor Retroclination 6. It increase the VH which make it worse in high angle cases 7. Short term skeletal effect e. Design A. The original design 1. U6s, U4s & L4s delta clasps. 2. labial bow, 3. Ball end clap between lower incisors. 4. 45 degree blocks it made from hot acrylic. 5. HG tube.
  • Mohammed Almuzian, 2013 40 6. Anchorage The anchorage component of the TB comes from  AP from reciprocal anchorage of the block as well as HG if it is added  Transversely from reciprocal anchorage around the screw B. The modified design by Clark in 2010 1. Delta clasps on U4, U6,L4 (Delta clasp is preferable because it will not open by insertion and removal) 2. No labial arch because the ULS will retraction by the effect of lower lip. 3. Ball end clasp mesial to L3s 4. Midline screw 5. Inclined bite plane of 70-75 with 7-8mm thickness the cover up to half of lower 5. The reason for this is to prevent interference with clasping of lower premolars and to allow potential grinding of upper block with sufficient acrylic remaining as a ramp to support posturing. 6. Interincisal opening in deep bite case should be 2mm and in high angle case should be 5mm to control lower posterior teeth eruption. 7. Lowe lingual flange extend posteriorly to L6 and L7 for better anchorage C. Currently favoured design features A national UK survey in 2000 by Spicer in Bristol discovered that the following was the most popular.
  • Mohammed Almuzian, 2013 41 1. URA: Cribs on the 4&6, A labial bow, Midline screw, Blocks on 4,5,6, 2. LRA: cribs on 4&6, incisor capping, blocks on 4,5. at a steep angle of 70 degrees to the occlusal plane and should be mesial to the lower 6, permitting removal of the lower molar crib and grinding of the upper block if accelerated eruption of these teeth is required. D. Labial arch 1. In order to maximize the TB effects it is better to include the upper buccal teeth only (without labial bow) and to involve all lower post teeth. So, the result would be distalising the upper post teeth while the ULS will be moved by the effect of lower lip and the traction of the transeptal fibres following U buccal teeth movement (Lee et al 2005). 2. Qureshi 2007 found that the use of labial bow increase LLS proclination and more mandibular growth. 3. A recent RCT had shown that the presence or absence of a labial bow had no effect on maxillary incisor retraction or skeletal change. Yaqoob O, DiBiase 2011 . Compliance may well be improved by an absence of upper labial wirework. 4. Sometime lower labial arch can be added if the LLS are spaced. E. Posterior attachments Additional headgear produced more maxillary restraint and less rebound force on the lower teeth which lead to reduce lower incisor proclination. Parkin et al (2001). The purpose of this study was to compare the skeletal and dental changes contributing to Class II correction with 2 modifications of the Twin-block appliance: Twin-block appliances that use a labial bow (TB1) and Twin-block appliances that incorporate high-pull headgear and torquing spurs on the
  • Mohammed Almuzian, 2013 42 maxillary central incisors (TB2). After pretreatment equivalence was established, a total of 36 consecutively treated patients with the TB1 modification were compared with 27 patients treated with the TB2 modification. Both samples were treated in the same hospital department and the same technician made all the appliances. The cephalostat, digitizing package, and statistical methods were common to both groups. The results demonstrated that the addition of headgear to the appliance resulted in effective vertical and sagittal control of the maxillary complex and thus maximized the Class II skeletal correction in the TB2 sample. Use of the torquing springs resulted in less retroclination of the maxillary incisors in the TB2 sample when compared with the TB1 sample; however, this difference did not reach the level of statistical significance Indications for concurrent headgear with functional appliances:- 1. Maxilla is very prominent 2. Proclined LLS. 3. Long face/'high angle' case F. Anterior attachments 1. Addition of double cantilever Z spring or anterior screw with torqueing spring to deal with class II D2. The bite registration is taken with the buccal segment relationship in an over corrected position, this may result in an edge-to-edge incisor position or a slight reversed overjet. However, by ensuring that there is 7–8 mm of separation in the buccal segments, there should be no incisal interference as the upper labial segment is proclined. It is also essential to have sufficient height of the blocks to ensure that the patient is more comfortable posturing forwards than closing in centric relation (Dyer and Sandler 2002). The advantages of this technique are:
  • Mohammed Almuzian, 2013 43  As advancement of the upper labial segment occurs simultaneously with sagittal correction the patient should never have an increased overjet placing them at risk of trauma due to prominent upper incisors.  This technique also prevents patients being left with an increased overjet if they fail to comply with the functional phase following upper incisor proclination.  Theoretically increase the upper posterior teeth distalization and reduce the LLS proclination because of the altered anchorage balance. 2. Addition of southern end clasp to the upper and lower incisors will enhance the skeletal effect and reduce upper incisor retroclination and lower incisor proclination (Trenouth and Desmond, 2012). The Southern end clasp was originated by DiBiase and Leavis. It locks the tooth surface against the acrylic base plate providing greater control over the axial inclinations of the incisors. The design is similar to the original Jackson clasp. But it has a problem when expansion by midline screw is wanted. 3. Acrylic capping of the lower incisors is commonly practiced, but this has been shown to be ineffectual in preventing proclination Young & Harrisson 2005 but it might cause demineralization (Dixon, 2005). 4. Flapper spring can be added similar to Southern end clasp and result in resulted in less retroclination of the maxillary incisors, Parkin 2001 5. Torquing spring: the claimed advantages are to control retroclination of ULS. The positive effect of the torquing spring had been proved by Harridine and Gale in 2000.
  • Mohammed Almuzian, 2013 44 f. Advancement  It can be activated in asymmetrical way to correct ML deviation  One go or incremental advancement of functional appliances? This was recommended by Petrovic 1975 and Rabie et al 2003. The theoretical purposes of incremental advancement: 1. Repeated stimulation of lateral pterygoid resulting in more mandibular growth. If the appliance is stretched as one go then the advantages of lateral pterygoid will be lost. 2. Less dentoalveolar effect. 3. Better patient compliance.  RCT compared the effects of twin-block treatment with a single advancement to an edge-to-edge bite and the incremental advancement (Banks et al 2004). This excellent paper by the developer of this particular incremental mechanism clearly showed no advantage for the incremental method in terms of process or outcome of the treatment. g. Clinical tips 1. It is recommended to trim the acrylic palatal to ULS to allow spontaneous alignment by the lower lip and the stretch of transeptal fiber. 2. Always check the difference between OJ and reverse OJ since the difference is fixed and this is a good landmark of the treatment progress
  • Mohammed Almuzian, 2013 45 h. Effectiveness of the Twin-block appliance compared to normal 1. Lund & Sandler 1998: This prospective controlled study investigated the net effects of the Twin Block functional appliance taking into account the effects of normal growth in an untreated control group. statistically significant restraint in the maxillary growth was observed. Forward growth of the mandible. Dentoalveolar effect as usual. 2. O’Brien 2003 9TB, CG, OJ 7mm, 8-10years) 73% dentoalveolar and 27% skeletal) i. Profile changes: O’ Brien 2009 did a study to compare the effect of TB on the facial profile using silhounte tracing for treated and untreated patient who had been rated by their peers and teachers and found that children with Class II malocclusion, treated with Twin-blocks in the mixed dentition, had profiles that were generally perceived as more attractive than those of an untreated cohort, by both peers and teachers. However, these differences were small. j. Psychosocial benefits of early orthodontic treatment with the Twin- block appliance O’Brien 2003 RCT study Results showed that early treatment with Twin- block appliances resulted in an increase in self-concept and a reduction of negative social experiences. FAQ about functional appliance I. Treatment duration Treatment should continue for at least 12 months to allow intermediate collage fibres (type 3) to change to more stable one (type 1) (McNamara 1990 & Voudouris 2003)
  • Mohammed Almuzian, 2013 46 II. Advantages of two stage treatment with the functional appliance King 1990 1. Better cooperation. (True, O’Brien 2003, 2009 with regard to TB treatment early treatment 18% failure but late 33%) 2. Psychosocial advantages (true O’Brien 2003) 3. Elimination of gingival/palatal trauma. Questionable? 4. High trauma with increased overjets >9mm (Todd & Dodd 1983) (45% 10 yr olds with OJ more than 9mm have traumatised incisors compared to 27% if the OJ was less than 9mm especially if the lip is incompetent) however RCT comparing early versus late treatment concluded:  all groups experienced trauma  very early treatment may prevent trauma but not cost effective (Koroluk et al 2003)  So that, the provision of a mouthguard is recommended to try to prevent trauma for patients with an increased risk of trauma (contact sports, large OJ).  Latest Cochrane review confirm the trauma prevention benefit. 5. Eliminate growth/local disturbances before they have had time to act fully. Questionable? 6. Craniofacial tissues more malleable so more favourable changes in skeletal and dental relationship achieved but may not be clinically significant. (true for short term, Tulloch, 2004, Kelling, 2008, O’Brien 2003) 7. Less root resorption than one phase (Brin 2003 use the data of UNC and prove that) III. Advantages of one stage treatment with the functional appliance 1. Better teeth clasping 2. Little cost 3. Growth still present
  • Mohammed Almuzian, 2013 47 4. Less risk of burning patient co-operation. Patient has time expiry approximately 3yrs which can be lost in the first phase leaving no compliance in the second phase. 5. Soft tissues do not mature until 12-14yrs with vertical growth of lips this might affects stability of corrected OJ 6. Extraction decision is easy and less 50% less than two phase treatment (Tulloch 2004) 7. Better final occlusion (O’Brien, 2009) 8. No difference from early treatment in term of skeletal, dental and psychological results (Tulloch 2004, O’Brien 2009, Dolce 2007, Harrison, 2007) IV. Stability of myofunctional appliances results • Maxillary changes more stable than mandibular changes.(Weislander, 1993) • Mandibular skeletal changes all lost after 2 years. Tulloch et al 2004 • 58% dental relapse (Pancherz, 1991) • Good buccal interdigitation reduces dental relapse (Pancherz and Fackel, 1990) and (Tulloch et al., 1990) V. SAQs How long TB should be? At least 1 year to allow remodelling of fossa and the intermediate fiber to be be changed to type 10 stable fiber (Lee 2013) because in the beginning the dominant fiber are type II (Rabie 1979) which resulted from activation of lateral pterygoid muscle. What factor which normally influences The overjet should be fully reduced and no longer a factor.
  • Mohammed Almuzian, 2013 48 extraction decisions should not apply at the end of functional appliance treatment? What additional factors will probably be present which were not present at the start of functional treatment? a) Upper incisor retroclination b) Lower incisor proclination c) Distal tipping of other upper teeth d) Differential growth of the jaws during the functional phase How exactly would you assess the factors in question 3? A cephalometric radiograph to measure all these factors. How are these factors in question 3 likely to influence your treatment from the end of the functional phase? 2a,b,c, will influence towards extraction or a more anchorage-providing extraction pattern or headgear. 2d is related and may reveal that overjet correction has been largely due to favourable growth as opposed to lower incisor proclination and that extractions are less indicated. What twin-block design features would you specifically choose in a patient with an anterior open bite? Avoid any acrylic or wirework which prevented eruption of the incisors. no torquing spurs on the upper incisors and no acrylic or ball-clasps on the lowers High-pull headgear. Spinner or passive tongue thrust breaker NB: As Tulloch 1998 points out, there is a widespread belief that children who grow vertically will respond less well to class 2 treatment, but this is not well documented or understood. The study
  • Mohammed Almuzian, 2013 49 by Ruf and Pancherz (1997) found no evidence to support this view. The “hyperdivergent” cases in fact showed 1 mm. better mandibular response than the “hypodivergent” cases although this was not statistically significant. This evidence suggests that ‘high angle’ cases are no reason to avoid functional appliances because of the potential effects on growth What twin-block design features would you specifically choose in a patient with upright upper incisors (not proclined)? You would probably opt for torquing spurs to minimise further retroclination of the upper incisors. What twin-block design features would you specifically choose in a patient in the early mixed dentition? In the absence of premolars to crib, you might well opt for features giving more retention on the incisors such as upper torquing spurs or even Southend clasps and lower ball-clasps +/- acrylic capping. What twin-block design features would you specifically choose in a patient with a very deep overbite? Wirework to impede further eruption of the upper incisors would be sensible such as torquing spurs and in the lower appliance, incisor capping An absence or early removal of molar cribs in order to permit eruption of the molars to level the curve of Spee at an earlier stage.
  • Mohammed Almuzian, 2013 50 Aust Orthod J. 2012 Nov;28(2):190-6. An investigation of cephalometric and morphological predictors of successful twin block therapy. Fleming PS1 , Qureshi U, Pandis N, DiBiase A, Lee RT. Author information Abstract OBJECTIVE: To identify predictors of overjet reduction, changes in mandibular length (Co-Me) and antero-posterior changes in mandibular position (Pog-Vert) during Twin Block therapy. METHODS: Pre- and post-treatment cephalograms of 131 participants were analysed (Mean age 12.73 years +/- 1) following Twin Block therapy. RESULTS: Mean annualised overjet reduction was 7.29 mm (+/- 2.99) with chin projection improving by 2.66 mm (+/- 5.37). The magnitude of the initial overjet was a strong predictor (95% CI: 0.30, 0.77, p < 0.01) of overjet reduction and change in chin position (95% CI: 0.08, 0.77, p = 0.02). Greater forward movement of Pogonion occurred if there was greater retrusion of Pogonion at the outset (95% CI: 0.15, 0.45, p < 0.01). No prognostic relationship was noted for other potential cephalometric predictors including pretreatment mandibular lower border morphology and Co-Go-Me angle. CONCLUSION: No relationship between mandibular morphology, vertical skeletal pattern and favourable dentoalveolar and skeletal responses to Twin Block therapy could be found. These results require confirmation on an external sample. Eur J Orthod. 2013 Jan 4. [Epub ahead of print] An extended period of functional appliance therapy: a controlled clinical trial comparing the Twin Block and Dynamax appliances. Lee RT1 , Barnes E, Dibiase A, Govender R, Qureshi U. Author information Abstract SUMMARYThe aim of this clinical trial was to compare the hard- and soft-tissue effects of 15 month full-time functional appliance therapy with Twin Block (TB) and Dynamax (Dx) appliances. The effects on both hard and soft tissue were analysed using cephalograms and three-dimensional optical surface laser scans. One hundred and three subjects with a class II division 1 malocclusion, and a minimum overjet of 7mm were available for analysis following stratified randomization according to gender and age. Data was collected at the start of treatment, 15 month therapy, and after 3 month post-treatment observation. Statistical analysis was conducted using analysis of covariance. The results demonstrated both appliances corrected the overjet with significantly increased skeletal
  • Mohammed Almuzian, 2013 51 dimensional changes with the TB compared with the Dx with forward movement of pogonion of 5.2mm (TB) and 0.7mm (Dx) P = 0.003. In addition, significant changes occurred particularly in the vertical dimension where there was also an increase in total anterior face height in both groups (TB = 6.4mm, Dx = 5.5mm) and significant (P = 0.003) mandibular length changes were also observed (TB = 7.2mm, Dx = 3.8mm). The cephalometric soft-tissue changes were significantly different between the two appliances at soft-tissue pogonion (TB = 9.8mm, Dx = 4.6mm, P = 0.001). Laser scan three- dimansional changes showed significant difference in the lower labial sulcus region where forward movements were observed (TB = 8.2mm, Dx = 6.2mm; P = 0.04). Overall these changes appear to be greater and more stable than those achieved in a previous 9 month study.