Deep overbite by almuzian

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  • 1. UNIVERSITY OF GLASGOW Orthodontic management of deep overbite Personal note MOHAMMED ALMUZIAN 1/1/2013 .
  • 2. Mohammed Almuzian, University of Glasgow, 2013 Page 2 Table of Contents Definition.......................................................................................................................4 Prevalence......................................................................................................................4 Classification.................................................................................................................4 True rotation, matrix rotation & apparent total rotation as described by Bjork 1969 ..7 Features of low angle or short face syndrome ..............................................................8 Aetiology deep overbite, .............................................................................................11 Indication for treatment of deep OB ...........................................................................14 Principles of deep incisor overbite reduction..............................................................14 Consideration factors for the method of treating DOB...............................................15 Mechanics for overbite reduction................................................................................17 In details ......................................................................................................................19 Removable Appliances................................................................................................19 Indications ...................................................................................................................19 Extraoral traction.........................................................................................................20 Dahl appliances ...........................................................................................................20 Begg Technique and Tip edge Technique,..................................................................21 Lingual appliance ........................................................................................................21 Fixed appliance setting................................................................................................21 Fixed appliance with continuous Arch Mechanics .....................................................22 Auxiliary appliances....................................................................................................24 Functional Appliances.................................................................................................24 Sectional archwires and auxiliary archwires...............................................................25
  • 3. Mohammed Almuzian, University of Glasgow, 2013 Page 3 Advantages of segemental archwires ..........................................................................28 Disadvantages of segmental mechanics ......................................................................29 Indications for segemental archwires..........................................................................29 Investigations comparing reverse curves of Spee AW (modified Tweed technique) to Burstone mechanics for overbite reduction.................................................................29 Investigations comparing reverse curves of Spee AW (modified Tweed technique) to sectional arches for overbite reduction (Rickett utility arch)......................................30 Absolute Anchorage....................................................................................................30 Surgical treatment of the Deep Overbite.....................................................................30 Stability of OB correction ...........................................................................................31 Summary of the evidences ..........................................................................................31
  • 4. Mohammed Almuzian, University of Glasgow, 2013 Page 4 Deep overbite Definition  Overbite can be described as the vertical overlap of the upper and lower incisors measured parallel to occlusal plane with the posterior teeth on occlusion when viewed anteriorly. (BSI 1983).  OB measured perpendicular to occlusal plane in mm or ratio. Prevalence  Deep bite prevalence is 8% in US  Blacks are 10 times more likely to have an AOB  Deep overbites are 6 times more frequent in whites. Classification 1. Skeletal 2. Dental 3. Averaged value when the upper incisors teeth overlap one third to a half of the lower incisors. 4. Increased 5. Reduced, 6. Complete when there is contact between the lower incisors and either the upper incisors or the soft tissues, 7. Incomplete which at its extremities no vertical overbite exists and indeed an anterior open bite can exist.
  • 5. Mohammed Almuzian, University of Glasgow, 2013 Page 5 Type of growth of the mandible Nielsen et al 1991 1.Normally A. The direction of condylar growth is vertical, with some anterior component, B. Always there is a balance between APH and PFH growth to achieve normal FH. If this is lost then either long or short face might develop C. AFH depend on the 1. eruption of the maxillary and mandibular posterior teeth 2. growth at the posterior dentoalveolar area 3. The amount of sutural lowering of the maxilla. 4. Surface remodelling at the anterior region of the mandible D. PFH depend on the 1. Downward growth of posterior cranial fossa 2. Lowering of the temporomandibular fossae 3. Condylar growth. 4. Surface remodelling at the posterior region of the mandible 2.In anterior or forward rotation  If the incisor occlusion is stable, the overbite remains unchanged during the growth period & the fulcruming point is located at the front teeth.  If the incisor occlusion is unstable, the fulcruming point is located further back along the occlusal plane. In this situation the bite normally becomes increasingly deep over time as the result of greater posterior face height increase in combination with lack of anterior tooth contact. This deterioration of the occlusion is most pronounced during puberty when
  • 6. Mohammed Almuzian, University of Glasgow, 2013 Page 6 growth intensity is at its greatest, but continues throughout the growth period. Patients with a pronounced tendency to anterior growth rotation and a deep bite should therefore be treated early and the occlusion supported throughout the growth period. Retention, especially in the mandibular arch, must also be maintained until mandibular growth is completed.  The erupting dentition in this type of mandibular growth characteristically undergoes a considerable amount of mesial migration of both the maxillary and mandibular teeth with some degree of proclination of the mandibular incisors. Where the amount of mesial migration of the lower posterior teeth does not equal the advancement of the incisors by proclination (due to trapping behind upper incisors), secondary crowding of the front teeth frequently develops. 3.In posterior rotation of the mandible  If dentoalveolar growth is greater than vertical condylar growth, the resulting change in mandibular position is back ward or posterior rotation of the mandible. The increase in AFH is greater than in PFH, the mandible rotates posteriorly with the fulcrum at the condyle.  This posterior growth rotation may result in an anterior open bite, depending on the extent of vertical dentoalveolar compensation.  The associated dental eruption pattern of the posterior teeth is generally distal & vertical and in some instances the anterior teeth may even become more retroclined with time. Late crowding is common finding in this pattern of growth due to soft tissue maturation.  Because the centre for the growth rotation is located near the mandibular condyles, treatment should be postponed until after puberty or at least until the potential for backward or posterior rotation is reduced. The reason for late treatment is that
  • 7. Mohammed Almuzian, University of Glasgow, 2013 Page 7 A. The tendency to extrude the posterior teeth decreases when there is less active growth. B. In addition when treated orthodontically these patients are at increased risk for further mechanically induced posterior rotation by acceleration of their molar eruption and require careful control. C. The increased risk of extrusion in these patients is associated with their weaker masticatory musculature making vertical control an important consideration. True rotation, matrix rotation & apparent total rotation as described by Bjork 1969  The actual rotation or total rotation in humans is generally masked on average by 50% surface modelling within the jaws.  In a recent study of non-human primates, it was found that this modelling or intramatrix rotation in the Rhesus monkey masked the rotations by about 75% in the maxilla and 90% in the mandible.  This surface modelling causes, in most instances, the lower border of the mandible to appear almost unchanged in its inclination to the cranial base and has led to misinterpretations of the actual growth changes and tooth movements in humans.  An example of this is seen in Figure below where the change in mandibular lower border inclination over time, the so- called matrix rotation, was -7.3° whereas the actual, or true rotation, was as much as -16.4° anteriorly
  • 8. Mohammed Almuzian, University of Glasgow, 2013 Page 8 Features of low angle or short face syndrome 1. Skeletal features:  Short lower third of the face,  Class II skeletal relationship  Long maxilla  Short mandible  Broad square facial type. 2. Soft tissue features:  Increased exposure of maxillary anterior teeth and gingiva at rest and smiling  Competent lip  Acute LMA & NLA  High lower lip line  Hyperactive mentalis  Hypertrophied masseter.  Prominent chin 3. Cephalometric feature.(this is also predictors for skeletal deep bite) i. Increased MMPA ii. UAFH-LAFH ratio: Nahoum (1975) believed that patients with a dental open bite and a UAFH-LAFH ratio of less than 0.65 are considered to be poor risks for conventional orthodontic treatment alone. iii. Bjork’s seven features of posterior growth rotation (Bjork, 1969)  The condyle is inclined forward;
  • 9. Mohammed Almuzian, University of Glasgow, 2013 Page 9  The mandibular canal has a curvature greater than the mandibular contour;  The lower border of the mandible is rounded anteriorly and concave at the angle, due to bony deposition along the anterior region and Symphysis as well as resorption below the angle;  The symphysis is inclined forward within the face and the chin is prominent;  The interincisor angle increased  Interpremolar and intermolar angles are all increased;  The anterior lower face height is reduced with a tendency towards an increased overbite. iv. Jarabak ratio, Jarabak, 1972  PFH:AFH, 59 – 63% is normal; if more than 64 low angle case then the case is deep OB; if less than 58 then the case is high angle case, reduced OB v. Reduced dentoalveolar height in molar region and increased dentoalveolar height in incisor region due to strong muscle allowing molar eruption. (Neilsen, 1991). vi. The degree of dentoalveolar compensation or dysplatic First described by Bjork 1969 and later discussed by Solow. These can be measured through the following:  In the maxilla, the maxillary zone, measured as the angle between the palatal plane (ANS-PNS) and the maxillary occlusal plane (mean 10°±3 ), describes the extent of compensatory or dysplastic development.  In the mandible, the mandibular zone, measured between the mandibular plane (GO-GN) and the mandibular occlusal plane (mean 20°±4°), similarly describes possible compensation.
  • 10. Mohammed Almuzian, University of Glasgow, 2013 Page 10  If one or both of these measurements are increased in a patient with an increased vertical jaw relation, favorable dentoalveolar compensation is indicated.  On the other hand, if these measurements are normal or reduced in the same patient, either no compensation or dysplastic development has taken place.  This will help in determine the type of treatment. Eg. If the high angle case has no compensation or has dysplastic development, then treatment can be achieved through orthodontic treatment to initiate this compensation, but if the compensation is already present then the case is surgical. 4. Intraoral features  Deep bite  Class 2 D2 tendency  Reduced overjet  Wide upper arch  Lower incisor trapping behind upper incisors 5. Growth feature Usually anterior growth rotation 6. Path of closure Usually normal or may be associated with posterior mandibular displacement 7. IOTN and OB  Overbite measured from any of the lateral or central incisors with the largest vertical discrepancy is recorded.  It is also important to note if there is any gingival or palatal trauma as a result of the deep overbite
  • 11. Mohammed Almuzian, University of Glasgow, 2013 Page 11 Overbite and Open bite Overbite Open bite Grade and qualifier Grade and qualifier 2f Increased greater Than Or equal to 3_5 mm 2e Anterior or posterior open bite I mm • .2 mm 3f Deep overbite complete on labial or palatal 'issues but no Trauma 3e Anterior or posterior open bite 2.1 mm — 4 mm 4f Increased and complete overbite with labial or palatal trauma 4e Extreme lateral open bites greater than 4 mm Aetiology deep overbite, Naini 2006, dental update  Skeletal Factors.  Soft Tissues  Dental factors.  Growth Factors  Iatrogenic Factor I. Skeletal Factors. 1. Antero-posterior problem: Class II skeletal pattern with loss of occlusal contact allowing the incisors to overeupt or the mandible to rotate anteriorly. 2. Vertical problem: A reduced lower face height in conjunction with a class II jaw relationship often results in the absence of an occlusal stop to the lower incisors, which then continue to erupt leading to an increased overbite
  • 12. Mohammed Almuzian, University of Glasgow, 2013 Page 12 which exaggerated by anterior growth rotation of the mandible. (Mitchell 1996). II. Growth Factors In general the vertical growth continue to late age adulthood with the maxilla normally rotate upward and forward and mandible upward and forward in 80%. In forward growth rotation and loss of incisor stop an increased overbite will become worse unless the incisors have an occlusal stop. III. Soft Tissues a. High lower lip line, Nicole (1954) was the first to suggest that a high lip line was a feature of Class II division 2 malocclusion and deep bite, and this was confirmed by Ridley (1960). The higher the lower lip line, the more retroclined the upper incisors and the deeper the overbite. b. Hyperactive or “strap- like” lower lip  It mainly cause retroclination of the lower incisor with associated LLS crowding and deep OB and increased OJ.  Hyperactive lip bashes the lower incisors and the giggling forces leads to bone loss and periodontal breakdown with loss of attachment.  Methods of treatment tried with hyperactive lip: 1. Mentalis myotomy, 2. Lip bumpers to stretch muscle fibres, 3. If the lower incisors moved forward the using a permanent rigid retainer is mandatory c. Hyperactive Mentalis muscle causing retroclination of the upper incisors and then increase in the OB d. Hyperactive Masseter muscle,
  • 13. Mohammed Almuzian, University of Glasgow, 2013 Page 13  Adults with reduced anterior face height have increased bite force and also a different composition of muscle fibres in the masseter, which implicates muscles as a primary cause of malocclusion. Hunt 1992 found that long face syndrome has predominantly collage fiber type 1 which is weak and long acting while short face syndrome has more type 2 collagen fibres which is heavier and short acting.  Benington 1999 showed large muscle fibres in deep bite and small size muscle fibres in AOB  However (Proffit & Fields, 1983) believe that this muscle change is a result from malocclusion. IV. Dental factors. 1. The eruptive potential of the incisors with decreased inclination of the incisors 2. Diminution of palatal surface (cingulum) of the upper incisor crowns 3. Abnormal Crown-root angulations 4. Increased Incisors height (Mills 1989) 5. Thin incisors  NB: there are some dental feature associated with deep OB but cannot be considered as a causative factors including: I. increased Inter-incisal angle, but this not always the case, because in class 3 cases, the II angle is increased but the OB is reduced (Mills, 1989) II. abnormal Incisor edge-centroid relationship (Houston, 1972) V. Iatrogenic Factor  This is as in the case of treating Class II division 1 and instead of finishing the case into Class I, it is finished into Class II division 2 causing deep incisor overbite.
  • 14. Mohammed Almuzian, University of Glasgow, 2013 Page 14  Extraction of the primary canine will result in deep overbite. Stephan 1992. Indication for treatment of deep OB 1. In primary nor mixed dentition: No treatments is indicated in primary nor mixed dentition since most of the deep bite case resolved with growth. 2. In permanent dentition , treatment is indicated in the following scenarios:  Traumatic OB  Functional problems  Aesthetic problems (especially if it is associated with increased incisor and gingival show)  If it interferes with OJ correction. Principles of deep incisor overbite reduction 1. Levelling of the arch through molar and premolar eruption and extrusion (relative intrusion). Keeping in mind that in growing patient, the condyle will compensate the extrusion and maintain the AP relationship, but in the adult the condyle not compensate for that, however, the muscle activity adapt very well to the new position and help in the stability (McDowell & Baker, 1991). In adults, the slight hinging open of the mandible, associated with molar extrusion, seems to be stable. This may be due to the tendency to slight continued vertical growth found in adults by investigators such as Behrents (1986). 2. Incisor and canine intrusion (true intrusion) it is indicated in the following cases:
  • 15. Mohammed Almuzian, University of Glasgow, 2013 Page 15  Adult patient  Excessive maxillary incisors showing at rest  Long lower facial height.  Over erupted incisors  If elongation of the teeth after loss of periodontal support has occurred. 3. Proclination of lower incisor. This effect has been analysed by Eberhart et al (1990) who, for example, stated that 5 degrees of incisor proclination would reduce the overbite by 1 mm on average. 4. Distal tipping of posterior teeth (up righting of posterior teeth) 5. Surgery to change AP and vertical problems. Consideration factors for the method of treating DOB  Age  Patient compliance  OH  Patient concerns  Faial profile  Vertical height relationship  Amount of incisor show  Gingival thickness on the labial surface of incisors  Incisor inclination  Intra-arch  Incisor relationship. In details
  • 16. Mohammed Almuzian, University of Glasgow, 2013 Page 16 1. Age and growth remaining of the patient which may affect the degree of incisor show (it is preferable to accept some incisor show in growing patient since soft tissue maturation would mask some of the underlying problems) or the use of ABP according to the growth status 2. Patient compliance and OH 3. Patient concerns 4. Vertical height relationship. eg in high angle case it is better to avoid posterior teeth extrusion. 5. Faial profile: avoid proclination of incisors in full or convex profile. 6. Amount of incisor show. The incisors show depend on the following factors:  Lip length  Crown height  Lip activity  Gingival height and level  Anterior maxillary height (VME) 7. Incisor inclination 8. Gingival thickness on the labial surface of incisors 9. Intra-arch relationship like OJ, MR, crowding (if the arch is crowded or the OJ is reduced then reducing the OB by proclination of incisors is preferable) 10. Incisor relationship. In class 2 division 1 the aim of reducing OB is by intrusion of incisors, extrusion of molars. While in class 2 division 2 the aim of reducing OB is by proclination of incisors as well as intrusion of incisors, extrusion of molars.
  • 17. Mohammed Almuzian, University of Glasgow, 2013 Page 17 Mechanics for overbite reduction 1. Extraoral traction A. HG B. J hooks C. HG-tandem 2. Removable Appliances A. ABP B. Functional Appliances 3. Dahl appliances  Removable chrome bite plane  Fixed bite plane (essentially Maryland/Resin-bonded bridge retainer wings otherwise called metal palatal veneers)  Porcelain palatal veneers  Direct composite veneers  Definitive or temporary crowns. 4. Begg appliances 5. Tip edge appliances, 6. Lingual appliance 7. Fixed appliance A. Bracket setting  Bracket Positioning  Increase mesial angulation of the upper canines.  Partial ligation of the distally inclined canines  Banding second
  • 18. Mohammed Almuzian, University of Glasgow, 2013 Page 18 permanent molar  No laceback  No cinch back B. Fixed anterior bite planes.  Composite  Metal C. Intermaxillary mechanics  Class 2 bite corrector  Class II inter-maxillary elastics Archwires: A. Fixed appliance with continuous Arch Mechanics  Tweed mechanisim  Modified Tweed mechanics  Using localised intrusion bends  Archwires with step- down T loops or step in SS arch wires  Counterforce/ Rocking chair NiTi arch wires. (Modified Tweed mechanics)  Anchor bend approach  Auxiliary levelling arch B. Segmented Burstone Arch Wires mechanics C. Rickett’s utility arch 1. 8. Absolute Anchorage
  • 19. Mohammed Almuzian, University of Glasgow, 2013 Page 19 9. Orthognathic Surgery In details Removable Appliances Indications 1. Growing patient  Providing that the rate of molar eruption does not exceed the relative rate of vertical condylar growth, there should be no backward mandibular rotation. However he stability of posterior (extrusion may be questionable in non-growing patient, but, the muscle activity adapt very well to the new position and help in the stability (McDowell & Baker, 1991)  When the rate of vertical growth of the buccal segments is greater than the vertical condylar growth however, a backward mandibular rotation will occur. Also, in non-growing patient, the molars will tend to reintrude under the forces of the occlusion once the appliance is withdrawn. This tendency can be resisted to a degree if the treatment creates a stable incisor relationship. 2. With a short lower facial height, 3. Excessive curve of Spee, 4. Moderate-minimal incisor display because increase in the interlabial gap which may worsen the gingival show. 5. Other uses include protection of the lower incisor brackets from being debonded
  • 20. Mohammed Almuzian, University of Glasgow, 2013 Page 20 Extraoral traction  J hooks: (Linge and Linge 1983 show that J hook cause root resorption). Degushi 2008 compared TAD with J hook for intrusion and found the result is 3.1 and 1.3mm respectively.  Cervical pull HG to molars Dahl appliances  Originally described by Dahl in 1970.  The Dahl appliance is a removable or cemented cobalt chrome appliance which covers the palatal surfaces of the maxillary anterior teeth.  This allows contact of the mandibular anterior teeth with the appliance, holding the posteriors out of occlusion.  This, in turn, promotes intrusion of the anterior teeth and eruption of the posteriors, thus providing space anteriorly.  It has been shown in an implant-cephalometric study to result in intrusion of the anterior teeth by an average of 1.05 mm, and eruption of the remaining teeth, averaging 1.47 mm after 6–14 months, without causing undue incisor proclination or TMD problems.  It reduces nocturnal bruxism;  Dhal appliance is not successful in adult as the free-way is increased in this group of patient due to dental wear.  Current types of Dahl 'appliances' Briggs 1997 1. Removable chrome bite plane 2. Fixed bite plane (essentially Maryland/Resin-bonded bridge retainer wings otherwise called metal palatal veneers) 3. Porcelain palatal veneers
  • 21. Mohammed Almuzian, University of Glasgow, 2013 Page 21 4. Direct composite veneers 5. Definitive or temporary crowns. Begg Technique and Tip edge Technique,  A 0.016 stainless steel high tensile strength wire is used. If the alignment of the anterior teeth is required, then an auxiliary 0.014 NiTi can be used. Circle hooks are placed mesial to the canines and an Anchor bend (2-3mm) in front of the first molar to intrude the incisors. Class II elastics (60gm, yellow) to extrude lower molars are used. Extrusion of the upper incisors by the class II elastic would be opposed by anchor bend in the upper arch wire while the lower posterior teeth will allow to erupt and LLS procline and thus the overbite will be reduced. Lingual appliance With lingual appliances, vertical control, as in levelling the curve of Spee or controlling the overbite, is clinically more efficient than in edgewise labial or conventional lingual appliances because  With a ribbon-wise configuration the big dimension of the archwire (0.025 inch superior-inferiorly) corrects the vertical plane  Also because the close proximity of the force application to the centre of rotation and root  The anterior bite effect. Fixed appliance setting 1. Increase mesial angulation of the upper canines. 2. Bracket Positioning 3. Partial ligation of the distally inclined canines 4. No laceback or cinch back 5. Banding second permanent molar. This means
  • 22. Mohammed Almuzian, University of Glasgow, 2013 Page 22  Additional vertical posterior anchorage  Molar extrusion is more distal and therefore a more effective wedge in the occlusion. Fixed appliance with continuous Arch Mechanics 1. Fixed appliances with continuous arch wires for flattening of the COS using rigid aw with or without reverse curve  This type of levelling can be accomplished with continuous arch wires, simply by placing an exaggerated curve of Spee in the maxillary arch wire and a reverse curve of Spee in the mandibular arch wire.  If using an 0.22” slot bracket, initial alignment is carried out using a 0.0175 twist flex or A 0.016” Niti.  This is then followed by a 0.016SS wire with a reversed or accentuated curve, and then by an 0.018SS wire to complete the levelling (Proffit, 2000).  Rectangular AW can be used too: It creates torque to move the incisor roots lingually and Al-Qabandi et al. (1999) carried out a prospective randomised clinical study to compare the effects of rectangular and round arch wires in levelling the curve of Spee. They found no significant difference in proclination between these two groups. 2. Using localised intrusion bends 3. Archwires with step-down T loops or step in SS arch wires: indicated when there is a step between the anterior and posterior occlusal planes, in cases with moderate-to-minimal incisor display, and Class I occlusions. 4. Counterforce/ Rocking chair NiTi arch wires. (Modified Tweed mechanics) Mode of action of Counterforce/ Rocking chair NiTi arch wires
  • 23. Mohammed Almuzian, University of Glasgow, 2013 Page 23 1. It acts by intrusion of anterior teeth 2. Extrusion of posterior teeth 3. Proclination of anterior teeth 4. Study by Clifford et al (1999) indicating that with a reverse curve of Spee in the lower archwire, the second molars in fact intrude rather than extrude. Advantages and indications of Counterforce/ Rocking chair NiTi arch wires 1. Earlier engagement of brackets with a rectangular wire is possible, which may speed overbite reduction. 2. Used with small inter-bracket spans with long range of action 3. Simultaneously reducing overbites and closing spaces without adverse tipping and “lingual collapse” into extraction sites 4. It can be used to treat AOB with Kim mechanics Disadvantages of Counterforce/ Rocking chair NiTi arch wires 1. Molar rotation distobuccally 2. Molar rolling buccally 3. Molar intrusion with premolar expansion 4. Incisor proclination 5. Asymmetric bite opening sometimes occurs 6. Hypothetically, 15 degrees of (unwanted) labial crown torque would result from leaving a curve of Spee of 5 mm at its greatest depth in a full-size archwire (0.022 x 0.028") to go completely passive. The means of preventing unwanted labial tipping of lower incisors during levelling of the curve if Spee are therefore: 1. a lower incisor prescription with lingual crown torque
  • 24. Mohammed Almuzian, University of Glasgow, 2013 Page 24 2. lingual crown torque in the rectangular wire 3. intra-arch traction This requires space in the lower arch usually via extractions 4. class 3 elastic This requires cooperation and may cause unwanted anchorage loss in the upper arch. Auxiliary appliances 1. Fixed anterior bite planes, either composite bite buttons or metal eg: bite turbo. But they can be used only if the OJ is not increase. 2. Class 2 bite corrector (some claim that it is not useful since bite corrector has a high pull HG effect) 3. Class II inter-maxillary elastics  These are an effective means of extruding lower molars. Mode of action  Extrusion of lower posterior teeth  They will extrude upper incisors, but the upper arch wires can be fabricated to oppose this incisor extrusion using a gable or anchor bend. However, even if accompanied by a millimetre of incisor extrusion, because the molar is closer to the condylar hinge axis.  Proclination of LLS 4. Intermaxillary traction springs (Saif spring) are now commercially available but still have a reputation for fragility  Class 2 elastic can be used in a triangular or check shape to allow correction of OJ and extrusion of post teeth at the same time Functional Appliances The modes of action in reducing the OB are
  • 25. Mohammed Almuzian, University of Glasgow, 2013 Page 25 1. By allowing the posterior teeth to erupt either during the active functional appliance through relieving of the acrylic from the lower part of the TB or during transient period through the use of steep and deep URA 2. Through changing the direction of growth pattern 3. By some proclination of the lower labial segment may occur Sectional archwires and auxiliary archwires 1. The “HG-tandem” The “HG-tandem” mechanics in the maxillary arch consisted of a 2 x 4 lever arch, cinched back and gabled 1 mm anterior to the molar band. It achieved around 1.9 mm of true incisor intrusion (Hans 1994) 2. Anchor bend approach  The first stage of the Begg technique is a classice version of this approach.  This approach is most useful in patient who has some growth. Mode of action:  Proclination of ULS  Overeruption of the molars, pitted against intrusion of the LLS. Technique:  Premolar teeth are by passed and only a loose tie is made to the canine.  An 0.016” SS arch wire is used, with an ‘anchor bend’ anterior to the first molar.  Light class II elastics are used to stabilise the lower molar against distal tipping, at a cost of some extrusion of the lower molar. The lower incisors are intruded while the class II elastics counterbalance the intrusion of the upper incisors.
  • 26. Mohammed Almuzian, University of Glasgow, 2013 Page 26  Mulligan (1980) advocated a similar approach using the edgewise appliance. The premolars and canines are again bypassed. Isaacson et al (1993) described it as a ‘2x4’ appliance (only two molars and four incisors included in the appliance set-up). 3. Auxiliary levelling arch  it made from 17 × 25 mil TMA  This arch inserts into the auxiliary tube on the molar and is tied anteriorly beneath the 0.018 ss base arch. In essence, this augments the curve in the base arch and results in efficient completion of the leveling by the same mechanism as a single continuous wire. Although the auxiliary leveling arch looks like an intrusion arch it differs in two important ways:  The presence of a continuous rather than segmented base arch and the higher amount of force.  Leveling will occur almost totally by extrusion as long as a continuous rather than segmented wire is in the bracket slots, while segmenting the arch makes intrusion possible 4. Segmented Burstone Arch Wires mechanics  AW which is a segmented base arch wire (so that there is no connection along the arch between the anterior and posterior segments) and an auxiliary depressing arch.  The buccal segments are first aligned, and then stabilised using a full dimension rectangular arch wire. The same for anterior segment  In addition to this, a heavy lingual arch is used to connect the right and left posterior segments.
  • 27. Mohammed Almuzian, University of Glasgow, 2013 Page 27  An auxiliary depressing arch is then placed in the auxiliary tube on the first molar and is used to apply force against the anterior segment.  It is recommended that no more than the four incisors should be incorporated in the intrusive segment, since if the canines were also included, this would shift the anchorage balance unacceptably towards distal tipping of the buccal segment teeth.  Burstone recommends that the dimension of the wire be .018x.025ss wire with a two and a half turn helix,  Alternatively, .019x.025 TMA without a helix.  The wire should lie just gingival to the incisor teeth when passive, and applies a light force of 10-15g when activated.  The Burstone intrusion arch is tied beneath the brackets, not into the bracket slots, which are occupied by the anterior segment wire.  It still has the effect of wanting to tip the incisors forward as they intrude, but two strategies may be employed to prevent this: 1. The arch wire may be tied back against the posterior segment – however, this can put some strain on the posterior anchorage. 2. The point of force application may be altered by tying it more distally. The force is then closer to the labial segment’s centre of resistance – this prevents incisor proclination without straining posterior anchorage.  It is quite feasible to intrude asymmetrically, which requires only adjusting the teeth that are placed in stabilizing and intrusion segments and tying the auxiliary intrusion arch in the area where intrusion is required. If intrusion is desired only on one side, either a cantilevered auxiliary wire extending from one molar or a molar-to-molar auxiliary
  • 28. Mohammed Almuzian, University of Glasgow, 2013 Page 28 arch can be used. The key is tying the auxiliary arch at the point where intrusion is desired  There is a modified Burston which used continure arch mechanics and the auxillary intrusive wire used in the Burstone technique. This is explained above as Auxiliary levelling arch. 5. Rickett’s (1979) utility arch  It is characterised by step-down bends between the first molar and the lateral incisors,  It is constructed in .016” square elgiloy.  In most cases, the arch wire is placed into the brackets with slight labial root torque to control the inclination of the teeth as the incisors move labially while they intrude.  Success in the use of these bypass arches depends on the forces being light.  Two weaknesses of the bypass arch systems limit the amount of true intrusion that can be obtained: I. Extrusion of the first molar can occur through distal tipping of molars as it is the only tooth available as posterior anchorage – high-pull headgear may need to be used, especially in non-growing patients. II. the intrusive force against the incisors is applied anterior to the centre of resistance – causes incisors to tip forwards as they intrude Advantages of segemental archwires 1. A long range of action, because of the long inter-bracket span 2. More easily estimated biomechanical effects 3. Frictionless
  • 29. Mohammed Almuzian, University of Glasgow, 2013 Page 29 Disadvantages of segmental mechanics 1. Complexity of fabrication 2. Poorer control of overall arch form 3. Less ‘fail-safe’ effect if the case is unsupervised for a period 4. Oral hygiene difficulties and patient discomfort if the wires impinge on the mucosa. 5. Proclination and wagon wheel effect Indications for segemental archwires 1. Adults 2. Deep overbite with the incisors are upright and the canines distally angulated and an intrusive force anterior to the centre of resistance of the incisors in the early stages is quite helpful. 3. Highly positioned canines with overerupted incisors 4. Gummy smile 5. Orthodontic decompensation for AOB case treated by segemental surgery. Investigations comparing reverse curves of Spee AW (modified Tweed technique) to Burstone mechanics for overbite reduction  Weiland 1996, found no significant difference bet Burstone mechanics and modified Tweed mechanics as an end result of the DP correction. But the Burstone mechanics cause more incisor intrusion while Tweed mechanics cause minimal intrusion in lower and high amount of molar extrusion
  • 30. Mohammed Almuzian, University of Glasgow, 2013 Page 30  Ng 2005 systematic review, The segmented arch technique in no growing patients produced 1.5 mm maxillary incisor intrusion and 1.9 mm mandibular incisor intrusion. Investigations comparing reverse curves of Spee AW (modified Tweed technique) to sectional arches for overbite reduction (Rickett utility arch) Dake & Sinclair, 1989 1. Both the Ricketts and Tweed-type arch levelling techniques were successful in overbite correction with minimal increases in mandibular plane angle and anterior facial height noted. 2. Mandibular incisors procline more in Ricketts group with a greater amount of post treatment uprighting and overbite relapse than the Tweed group. 3. Slightly more than 1 mm of mandibular incisor intrusion was noted in the Ricketts group but no incisor intrusion was seen in the Schudy group. Absolute Anchorage 1. Osseointegrated implants, 2. Onplants 3. Mini screws.  Degushi 2008 compared TAD with J hook for intrusion and found the result is 3.1 and 1.3mm respectively. Surgical treatment of the Deep Overbite  In case of an increased lower facial height the surgery may involve lower anterior dentoalveolar setdown and BSSO advancement.  In case of an reduced lower facial height the surgery may involve 3 point landing BSSO advancement.
  • 31. Mohammed Almuzian, University of Glasgow, 2013 Page 31 Stability of OB correction depend on: 1. Avoiding change in the facial height in non-growing 2. Long term retention if LLS proclined 3. Amount of the OB at the start 4. Normal II angle 5. Normal lower incisor edge to centroid 6. Build up diminutive cingulum plateau 7. VH tend to continue in teenager so the use of URA with ant bite plane as part time use is important. 8. Extraction and OB correction  Cochrane review by Millet 2007, There is no scientific evidence to establish whether orthodontic treatment, carried out without the removal of permanent teeth, in children with Class II division 2 malocclusion is better or worse than orthodontic treatment involving extraction of permanent teeth or no orthodontic treatment.  Simon and Joondeph (1973) have found that there is no correlation between overbite stability and extraction or non-extraction treatment. Summary of the evidences  Definition, (BSI 1983).  Prevalence Deep bite prevalence is 8% in US  Type of growth of the mandible, Nielsen et al 1991  True rotation, matrix rotation & apparent total rotation as described by Bjork
  • 32. Mohammed Almuzian, University of Glasgow, 2013 Page 32 1969  Bjork’s seven features of posterior growth rotation (Bjork, 1969)  Jarabak ratio, Jarabak, 1972  Aetiology deep overbite, Naini 2006, dental update  High lower lip line, Nicole (1954)  Hyperactive Masseter muscle, Hunt 1992  Benington 1999 showed large muscle fibres in deep bite and small size muscle fibres in AOB  However (Proffit & Fields, 1983) believe that this muscle change is a result from malocclusion.  Increased Incisors height (Mills 1989)  Abnormal Incisor edge-centroid relationship (Houston, 1972)  Extraction of the primary canine will result in deep overbite. Stephan 1992.  Keeping in mind that in growing patient, the condyle will compensate the extrusion and maintain the AP relationship, but in the adult the condyle not compensate for that, however, the muscle activity adapt very well to the new position and help in the stability (McDowell & Baker, 1991)  Proclination of lower incisor. This effect has been analysed by Eberhart et al (1990) who, for example, stated that 5 degrees of incisor proclination would reduce the overbite by 1 mm on average.  J hooks: (Linge and Linge 1983 show that J hook cause root re-sorption).  Degushi 2008 compared TAD with J hook for intrusion and found the result is 3.1 and 1.3mm respectively.  Dahl appliances, originally described by Dahl in 1970.  Rectangular AW can be used too: It creates torque to move the incisor roots lingually and Al-Qabandi et al. (1999) carried out a prospective randomised clinical study to compare the effects of rectangular and round arch wires in levelling the curve of Spee. They found no significant difference in
  • 33. Mohammed Almuzian, University of Glasgow, 2013 Page 33 proclination between these two groups.  Study by Clifford et al (1999) indicating that with a reverse curve of Spee in the lower archwire, the second molars in fact intrude rather than extrude.  Rickett’s (1979) utility arch  Investigations comparing reverse curves of Spee AW (modified Tweed technique) to Burstone mechanics for overbite reduction, Weiland 1996, found no significant difference bet Burstone mechanics and modified Tweed mechanics as an end result of the DP correction. But the Bur-stone mechanics cause more incisor intrusion while Tweed mechanics cause minimal intrusion in lower and high amount of molar extrusion , Ng 2005 systematic review, The segmented arch technique in no growing patients produced 1.5 mm maxillary incisor intrusion and 1.9 mm mandibular incisor intrusion.  Investigations comparing reverse curves of Spee AW (modified Tweed technique) to sectional arches for overbite reduction (Rickett utility arch) , Dake & Sinclair, 1989  Cochrane review by Millet 2007, There is no scientific evidence to establish whether orthodontic treatment, carried out without the removal of permanent teeth, in children with Class II di-vision 2 malocclusion is better or worse than orthodontic treatment involving extraction of permanent teeth or no orthodontic treatment.  Simon and Joondeph (1973) have found that there is no correlation between overbite stability and extraction or non-extraction treatment.