IntroductionWhat is orthodontics?Orthodontics is the specialist branch of dentistry concerned with the growth and development of the face and dentition, and the diagnosis, prevention and correction of dental and facial irregularities.15 OrthodonticsIntroduction  391What is malocclusion?  391Risk/benet considerations in orthodontic treatment  394Classication and occlusal  indices in orthodontics  396Patient assessment/examination  400Cephalometrics  403Principles of treatment planning  405Management of the developing dentition  407Class I malocclusion  410Class II division 1 malocclusion  412Class II division 2 malocclusion  413Class III malocclusion  415Removable appliances  417Fixed appliances  422Functional appliances  423Orthodontic management of cleft lip and palate  424Orthodontic aspects of orthognathic surgery  427The development, prevention, and correction of irregularities of the teeth, bite and jaw (GDC).What is malocclusion?Malocclusion is considered to be a variation of normal – so not all malocclusions require treatment. Treatment is considered when there is functional or aesthetic impairment. Orthodontic treatment is also increasingly used to treat facial deformities, usually in com-bination with orthognathic surgery, and to facilitate restorative pro-cedures (orthodontic-restorative interface).Malocclusion is a term introduced by Edward Hartley Angle and is dened as any deviation of the occlusion from the ideal.http://dentalebooks.com 39 2 • C L I N I C A L D E N T I S T RYPrevalence of malocclusionBased on morphology. The UK population can be classified as:Class I 50–55%Class II division 1 25–33%Class II division 2 10%Class III 3%using the British Standards Institute’s Incisor Classification (p. 397).Based on need for treatment. Assessment of 12-year-old children using the Index of Orthodontic Treatment Need (IOTN) – Dental Health Component (p. 398): one-third of children have a malocclu-sion showing a need for treatment; one-third have malocclusions which have borderline need for treatment; one-third have a maloc-clusion with little or no need for treatment.Who provides orthodontic care?All dental clinicians must be ‘orthodontically aware’. Orthodontic appliance treatment is increasingly provided by specialists, often with the help of an orthodontic therapist, but the general dental practi-tioner (GDP) has a vital role to play. The GDP is the gatekeeper to orthodontic care and should be competent in the appropriate moni-toring and recognition of malocclusion, as timely referral or treat-ment can alleviate orthodontic problems. The role of the GDP in orthodontics includes continuing preventive care, ‘orthodontically appropriate’ operative treatment such as management of primary molar problems, appropriate assessment of first permanent molars, monitoring of the developing occlusion, and simple treatment skills – often in conjunction with advice from a specialist. Good dental health is an essential prerequisite for future orthodontic treatment.The GDP will often wish to refer patients for advice or treatment. If in doubt, refer sooner rather than later, and before carrying out any intervention. The most dif-cult orthodontic problems are often those that have been referred too late, or have had previous unsuccess-ful or inappropriate orthodontic treatment. The GDP may refer to specialists working within primary or sec-ondary care.Not all patients with a malocclusion require orthodon-tic treatment.http://dentalebooks.com O R T h O D O N T I C S • 3 93Timing of orthodontic interventionWhen orthodontic treatment should be carried out is related to the type of problem and the developmental stage of the dentition.Primary dentition. Treatment is rarely indicated in the primary dentition.Possible exceptions include a malpositioned tooth causing marked mandibular displacement, supernumerary teeth, severe skeletal dis-crepancies or asymmetry (e.g. hemifacial microsomia).Early mixed dentition. Occasionally involves extraction of primary teeth, or interceptive procedures such as correcting a crossbite.Late mixed/early permanent dentition. Most treatment is carried out at this stage.Later treatment. Treatment involving orthognathic surgery is undertaken at the completion of growth. Treatment in adults is also increasingly being undertaken for cosmetic concerns and to facilitate restorative treatment.Why do orthodontic treatment?The many benefits of undertaking orthodontic treatment include:• improvement in function• reducing risk of traumatic injuries to protruding upper incisors• management of impacted teeth• relief of crowding to facilitate oral hygiene• psychological benefits of improved dentofacial aesthetics.Risks of orthodontic treatment include:• enamel decalcification• root resorption (occasional devitalization)• relapse.A risk-benefit analysis must be undertaken before embarking upon any course of treatment. Sometimes the GDP may be called upon to provide a second opinion to decide if a patient should undergo treatment if there are dental health issues or concerns around compliance.Scope of orthodontic treatmentOrthodontic treatment can be considered under the following headings:• Monitoring of the developing dentition.Interceptive treatment to avoid or simplify later treatment, e.g. ectopic canines, poor prognosis first permanent molars.• Management of problems of intra-arch alignment, e.g. crowding, spacing, ectopic teeth, transpositions.http://dentalebooks.com 39 4 • C L I N I C A L D E N T I S T RY• Management of problems of inter-arch alignment, e.g. overjet, overbite, midlines, crossbites.• Management of skeletal discrepancies – in mild to moderate cases this may involve orthodontic camouflage and in severe cases this may require a combination of orthodontics and orthognathic surgery.• Multidisciplinary orthodontics – orthodontic tooth movement to facilitate restorative dentistry, management of periodontal tooth migration, craniofacial deformity and orthodontic appliances to facilitate management of obstructive sleep apnoea by mandibular posturing.Risk/Benet considerations in orthodontic treatmentPotential benets of orthodontic treatmentCan be categorized as: improved dental health/function; improved appearance.Improved dental health/functionOrthodontic treatment has a number of possible dental health/functional benefits:Masticatory function. Mild to moderate malocclusion is unlikely to significantly affect masticatory efficiency. Severe malocclusion (e.g. anterior open bite; large overjet, reverse overjet) may make incision of food more troublesome and may produce social embarrassment.Dental caries. Significantly displaced teeth may predispose to plaque retention, which may increase the risk of dental caries.Periodontal disease. Significantly displaced teeth may predispose to plaque retention, which may increase the risk of periodontal damage.Overjet. There is evidence that anterior teeth with an increased overjet (>6 mm), and particularly when the lips are incompetent, are considerably more likely to suffer trauma. Peak incidence is before 10 years and unfortunately treatment is not commonly provided by this age. A slight increase in plaque accumulation on teeth having either an increased or reverse overjet has also been shown.Temporomandibular joint dysfunction (TMD). (See Chapter 14, p. 381) There is little evidence to suggest that malocclusion has any significant effect, or that orthodontic treatment brings any lasting benefit, on TMD.Tooth impaction. Orthodontic treatment may be used to prevent and correct tooth impaction.Overbite. Increased overbite may cause soft tissue damage to the palatal or lower labial mucosa.http://dentalebooks.com O R T h O D O N T I C S • 3 95Anterior crossbite. Accelerated gingival recession may occur around lower incisors related to upper incisors in linguo-occlusion. There is also a greater risk of attrition at the site of a premature contact.Conclusion. The threat posed to dental health by malocclusion is generally modest. However, in some specific malocclusion traits there is the potential for significant damage.Improved appearanceMalocclusion affecting appearance may also affect an individual’s self-esteem, elicit an unfavourable social response or provoke negative stereotyping.Self-esteem. Only limited information is available regarding the link between level of malocclusion and self-esteem. However, there is great variation between individuals’ perception of their appearance.Social response. Teasing may affect personality development.Stereotyping. It has been shown that faces evoke a more favourable response when there is normal anterior dental alignment, but that the level of background facial attractiveness is of greater importance.Conclusion. This is a difficult topic to investigate; intuitively it would seem that the chances of evoking an unfavourable social response are greater with more conspicuous dental defects.Potential risks of orthodontic treatmentRisks of orthodontic treatment include:Decalcication. Especially around fixed appliances if plaque control is poor and if the frequency of sugar intake is excessive. Caries is entirely preventable (Chapter 3) – all potential orthodontic patients must achieve and maintain excellent oral hygiene, avoid sugar in between meals and use fluoride preparations. It is essential that regular dental visits are maintained throughout orthodontic treatment.Root resorption. A small degree of root resorption (1–2 mm) occurs in the majority of people during orthodontic treatment. Rarely, root resorption can be a significant problem in some cases and is more likely with fixed than removable appliances. Use of heavy forces and a history of trauma may be predisposing factors.Gingival problems. Mild gingivitis in patients wearing fixed appli-ances is common. This is reversible, but requires careful control. Per-manent loss of attachment can occur in some cases, particularly if teeth are moved outside of the arch or excessively tipped.http://dentalebooks.com 39 6 • C L I N I C A L D E N T I S T RYPulp damage. Minor circulatory changes commonly occur during orthodontic treatment. In very rare circumstances this may lead to loss of vitality (e.g. previous trauma).Ulceration of the oral mucosa. May arise from fixed appliance com-ponents. Patients prone to oral ulceration (e.g. Epidermolysis bullosa) must embark upon treatment with care.Facial prole changes. Inappropriate retraction of the incisors may lead to ‘flattening’ of the facial profile.Enamel damage at debond. There is the potential for enamel damage when brackets are removed at the end of treatment.Headgear injury. Dislodged headgear can cause facial and ocular injury. It is essential that safety features such as the Masel safety strap, snap away modules, recurved Khloen bow and locking Khloen bow are used.Temporomandibular joint dysfunction. (See Chapter 14, p. 381) There is no strong evidence that orthodontic treatment can cause or treat temporomandibular joint problems.Relapse. Without the long-term use of retainers, orthodontic treat-ment is prone to relapse due to the elastic recoil of periodontal fibres, late mandibular growth and soft tissue maturational changes.Treatment failureTreatment failure in orthodontics may mean a failure to meet the occlusal objectives, the occurrence of excessive damage (see Risks of Orthodontics) during treatment, and poor patient satisfaction with the outcome (e.g. flattening of the profile). A number of factors can contribute to treatment failure including poor diagnosis and treat-ment planning, poor patient co-operation, unfavourable growth and poor communication.Conclusion. Orthodontic treatment should only be undertaken after careful consideration of the risks and benefits of treatment. To mini-mize the risks of treatment, it is essential that orthodontic treatment is only embarked upon in those with excellent oral health. It is essen-tial to have good patient compliance for treatment to be successful. In the long-term, retention is essential for maintaining the results of orthodontic treatment.Classication and occlusal indices in orthodonticsAn occlusal index is a rating or categorizing system that assigns a numerical or alphanumerical label to an individual’s occlusion.http://dentalebooks.com O R T h O D O N T I C S • 3 97Numerous types of index have been developed. Whilst some are used to classify malocclusion for diagnostic purposes, e.g. British Standards Institute’s Incisor Classification (Figure 15.1) and Skeletal Classifica-tion (Figure 15.2), other indices are designed to measure treatment need, e.g. Index of Orthodontic Treatment Need (IOTN) or treatment outcome, e.g. Peer Assessment Rating Index (PAR).Incisor classicationThe British Standards Institute’s (1983) classification of malocclu-sion, based upon the relationship of the lower incisor edges and the cingulum plateau of the upper central incisors (see Figure 15.1), is a useful index for the classification of malocclusion as it is based on the anterior teeth which are most visible to the orthodontist and patient:Class I. The lower incisor edges occlude with or lie immediately below the cingulum plateau of the upper central incisors.Class II. The lower incisor edges lie posterior to the cingulum plateau of the upper central incisors.Figure 15.1 Incisor classication. Class IClass IIdiv. 1Class IIdiv. 2Class IIIFigure 15.2 Skeletal patterns. Skeletal pattern 1 Skeletal pattern 2 Skeletal pattern 3http://dentalebooks.com 39 8 • C L I N I C A L D E N T I S T RYClass II division 1. The upper central incisors are proclined or of average inclination and there is an increased incisor overjet.Class II division 2. The upper central incisors are retroclined; the overjet is usually minimal but may be increased.Class III. The lower incisor edges lie anterior to the cingulum plateau of the upper central incisors; the overjet is reduced or reversed.Skeletal classicationThe skeletal classification (See Figure 15.2) relates the anterior limit of the mandibular base to the maxillary base with the head in the Natural Head Position;Class I skeletal pattern. Point B lies a few millimetres behind point A (Figure 15.3). The lower skeletal base lies a few millimetres behind relative to the upper.Class II skeletal pattern. The lower skeletal base is retruded (>2mm) relative to the upper.Class III skeletal pattern. The lower skeletal base is protruded rela-tive to the upper.Index of orthodontic treatment need (IOTN)The IOTN has two components, which can be assessed clinically or on study models:• Dental Health Component (DHC)• Aesthetic Component (AC).Figure 15.3 Cephalometric points and planes. FrankfortplaneMaxillaryplaneFunctionalocclusalplaneMandibularplaneFacial planeOrSPoBaArGoMePogBAANSPNSNhttp://dentalebooks.com O R T h O D O N T I C S • 3 99Dental Health Component (DHC) of IOTNThe DHC records the various aspects of malocclusion according to a hierarchy using the MOCDO acronym, where:M =Missing teethO =OverjetC =CrossbiteD =Displacement of contact pointsO =OverbiteThis provides a reliable and rapid method of assessing the occlu-sion. A specifically designed measuring ruler is used and a grade awarded on the basis of the single most severe feature of the maloc-clusion. The index has been validated as follows:Grades 1, 2 No/slight need for treatmentGrade 3 Borderline needGrades 4, 5 Need for treatmentLimitations. There is a shortage of scientific evidence to justify the hierarchy of the scale based upon dental health grounds. Nonethe-less, the DHC of IOTN provides a structured method for assessment of malocclusion.Aesthetic component of IOTNThe aesthetic component scores the need for treatment on the grounds of aesthetic impairment of the anterior teeth. The patient’s teeth are compared with 10 standard photographs ranked in order of attractiveness, 1 being the most attractive and 10 the least aes-thetically pleasing. The scale has been validated as follows:Grades 1, 2, 3, 4 No/slight needGrades 5, 6, 7 Borderline needGrades 8, 9, 10 NeedAt present the UK National Health Service funds orthodontic treatment for children where the IOTN is equal to or greater than DHC = 3 and AC = 6 (3.6).Potential uses of IOTNResource allocation. Enables identification of those most in need of treatment.Uniformity of assessment. Offers an objective structured assess-ment of malocclusion and the need for intervention.Screening. Can be used by GDPs for screening purposes.Patient advice. May be used to provide objective advice to a potential patient. The aesthetic component in particular can be used as a scale http://dentalebooks.com 40 0 • C L I N I C A L D E N T I S T RYto advise patients who may have unrealistic concerns about the appearance of their teeth.Peer assessment rating index (PAR)Used to determine orthodontic treatment outcome based upon dental-occlusal changes. The PAR index grades features of the pre- and post-treatment study models to derive a score of the improve-ment achieved with treatment. It measures the following features of the malocclusion:• overjet• overbite• centreline relationship• buccal segment relationship• upper and lower anterior alignment.Limitations. PAR is based solely on study models and does not account for changes in facial profile, iatrogenic damage, tooth incli-nation, arch width or posterior spacing, and is not appropriate for assessment of mixed dentition treatment.Patient assessment/examinationThe features of taking a history and examining a patient outlined in Chapter 7 apply. However, the following features are specifically rel-evant to an examination for orthodontic purposes.The aims of orthodontic assessment are to document and evaluate facial, occlusal and functional characteristics, to decide if there is a problem and, if so, what action is required.Notably important times for orthodontic examination are: early mixed dentition; early permanent dentition.As always, a logical structured approach must be followed to gather all the information efficiently and to ensure important fea-tures are not overlooked.The following sequence should be employed.Patient backgroundNote. Age; relevant medical history; relevant dental history, e.g. attendance record, oral hygiene, caries rate, trauma; social history: is there a complaint from the patient? Does the patient appreciate what orthodontic treatment involves? Level of parental support? Any friends/siblings having treatment?Clinical examinationExtraoral examinationNeed to consider hard and soft tissues.http://dentalebooks.com O R T h O D O N T I C S • 4 01Hard tissuesAssessment is aimed at noting any disproportion or asymmetry. The skeletal pattern has an important effect on the dental arch relation-ship and should be assessed in three dimensions with the head in a natural head position:Anterior–posterior. The relationship of the maxillary skeletal base to the mandibular base can be assessed in the profile view.Vertical. Need to assess the Frankfort–mandibular plane angle (normal, reduced, increased) and the lower facial height. The dis-tance from a point between the eyebrows (glabella) to the base of the nose (subnasale) should be approximately equal to that from sub-nasale to the underside of the chin (soft tissue menton), though normal variation exists.Symmetry. (view from the front) Is there any significant asymmetry? Asymmetry in the lower part of the face can be due to true skeletal asymmetry, a lateral displacement of the mandible on closure, or a combination of both. Soft tissue asymmetry may also be a contribu-tory factor.Soft tissuesLips. Lip contour Normal, everted, vertical? Lip line Where is the top of the lower lip relative to the incisors? Should cover about a third to a half of the upper central incisor crowns. Lip seal Are the lips com-petent (i.e. together with minimal muscular effort) with the mandible in the rest position? An attempt should be made to assess lip activity during swallowing.Beware of cases with marked lip ‘incompetence’, as the stability of upper incisor retraction may be questionable.Tongue. This may be difficult to examine. Some positions of tongue activity can be inferred from the occlusion. With incompetent lips the tongue will tend to come forward to help maintain the anterior oral seal (adaptive tongue thrust).By the end of the extraoral examination, a reasonable idea of what occlusal characteristics to expect should have been obtained. If they differ from the expected, ask why?Intraoral examinationLook at general features of dental health such as the level of oral hygiene, caries experience, gingival condition, tooth number and form and the size and condition of any restorations. Then examine each arch in isolation, followed by the two arches in occlusion.Lower archLabial segment. Count the teeth, assess crowding and the inclination of the incisors.http://dentalebooks.com 40 2 • C L I N I C A L D E N T I S T RYBuccal segment. Observe alignment problems (potential and present) and angulation of the canines.Upper archLabial segment. As for lower arch.Buccal segment. Determine angulation of the canines, note align-ment problems; if the permanent canine is unerupted, is it palpable bucally?In occlusion. Check the path of closure as the teeth are brought together. Is there a premature contact and associated mandibular displacement?Incisor relationship. Classify this according to British Standards Institute’s Incisor Classification (p. 397).Overjet. Measure to the nearest millimetre.OverbiteRelationship between the incisors in the vertical plane.OverjetRelationship between the incisors in the horizontal plane.Overbite. Is it average, increased or reduced; complete or incomplete?Centrelines. Check the relation of each dental midline to the facial midline and also to each other.Arch anterior/posterior relationship. Check the canine and buccal segment relationship.Arch buccolingual relationship. Check for any crossbites. If there is a posterior crossbite, is it bilateral or unilateral, and is there an associ-ated displacement?TMJ assessment. An assessment should be made of any TMJ and myofascial symptoms or signs.Diagnostic recordsThe following diagnostic records will aid assessment of the patient’s orthodontic status:Study modelsAllow a more accurate assessment of some aspects of the occlusion and facilitate measurement. Models provide a good baseline record, aid the explanation of any problem to both the patient and parent, and can be used for PAR assessment. Diagnostic set-ups, where the http://dentalebooks.com O R T h O D O N T I C S • 4 03teeth are repositioned on the model to simulate treatment, may be helpful for consent and to assess tooth fit.RadiographsRadiographs, if justified, should only be taken after a clinical exami-nation has been carried out. A panoramic-type view is often appro-priate, although this may need to be supplemented by other views where indicated, e.g. history of incisor trauma, localization of unerupted teeth. A lateral cephalometric radiograph may be required in certain cases. As with the clinical examination, radiographs should be examined in a standard, structured manner and be reported upon (see Chapter 8).Having completed the examination, a precise summary of the patient’s condition should be recorded within the case notes.CephalometricsCephalometricsThis is the measurement and study of the dental, skeletal and soft tissue relationships of the craniofacial complex on skull radiographs taken in a standardized manner. Serial radiographs can also be analysed to determine growth and treatment changes using regional superimposition.A lateral cephalometric radiograph is taken under standardized conditions in order that measurements can be compared between patients and between films of the same patient taken on different occasions. The head is held in a cephalostat so that there is a fixed constant relationship between the head, film and X-ray source.In addition to clinical examination, analysis of a lateral cephalo-graph permits a more detailed evaluation of facial and dentoskeletal structures to aid diagnosis and treatment planning, especially in cases with a skeletal discrepancy. It also provides baseline measure-ments to monitor the effects of growth and treatment.A lateral cephalograph is not needed, or justied, for all orthodontic assessments.Analysis of a lateral cephalographAn outline should be traced as in Figure 15.3. The following defini-tions are important:• Sella (S) – midpoint of sella turcica• Nasion (N) – most anterior point on the frontonasal suturehttp://dentalebooks.com 40 4 • C L I N I C A L D E N T I S T RY• A-point (A) – deepest point on the maxillary profile between the anterior nasal spine and the alveolar crest• B-point (B) – deepest point on the concavity of the mandibular profile between the alveolar crest and the point of the chin• Posterior nasal spine (PNS) – tip of the posterior nasal spine• Anterior nasal spine (ANS) – point of the bony nasal spine• Gonion (Go) – most posterior, inferior point on the angle of the mandible• Menton (Me) – lowermost point of the mandibular symphysis• Pogonion (Pog) – most anterior point on the bony chin• Porion (Po) – highest point on the bony external acoustic meatus• Orbitale (Or) – most inferior point on the margin of the orbit• Articulare (Ar) – point of intersection of the projection of the surface of the condylar neck and the inferior surface of the basiocciput• Basion (Ba) – most posterior inferior point in the midline on the basiocciput.From these points a number of planes can be constructed:Frankfort plane. Po–Or. It was once believed this plane was horizon-tal when the head was held in the natural head position, though this is not always the case.Facial plane. N–Pog. Indicates the general orientation of the facial profile.Maxillary plane. ANS–PNS. Indicates the orientation of the palate.Mandibular plane. Go–Me. Indicates the orientation of the mandible.Occlusal plane. Variety of definitions used. Functional occlusal plane (FOP) is a line following the occlusion of the molar and premo-lar teeth.Cephalometric measurements should be interpreted with caution as there are errors in the technique. If the clinical and cephalometric findings are contradictory, more credibility should be given to the clinical findings.Cephalometric analysis tends to utilize angular values which change little with either sex or age. A vast array of measurements have been suggested; the more common are listed in Table 15.1.The anterior-posterior skeletal discrepancy is determined using angle ANB (Table 15.2). The vertical skeletal discrepancy is evaluated using the Max/Man plane angle. As the discrepancy in either increases, so do the difficulties in dealing with the problem.As well as skeletal relationships, a cephalograph can also be used to determine incisor inclination. This permits judgements to be made as to the potential for inclination changes to correct incisor position, http://dentalebooks.com O R T h O D O N T I C S • 4 05TABLE 15.1 Mean cephalometric values (White Caucasian norms)Mean Range (+ or −)SNA 81° 3SNB 79° 3ANB 3° 3Maxillary-mandibular planes angle 27° 4Upper incisor/maxillary plane 108° 6Lower incisor/mandibular plane 92° 6Upper incisor/lower incisor 133° 10Lower incisor/A–Pog0 mm 2Upper lip/aesthetic plane−4 to −6 mmLower lip/aesthetic plane−2 to −4 mmTABLE 15.2 Relationship of ANB angle to skeletal patternAngle ANB (degrees) Skeletal pattern2–4 1>4II<2IIIthe need for bodily movement, and the likelihood of successful cam-ouflage treatment.Principles of treatment planningTreatment planning is affected by many factors. In most instances the GDP should obtain a specialist opinion.Aims of treatmentThe aim of treatment is to produce an occlusion that is stable, func-tional and acceptable in appearance. Treatment should only be con-sidered in those with high motivation and excellent dental health.ConsiderationsSpace requirements. It is usual to plan the lower arch first. The form (or shape) of the lower arch is usually accepted and the position of the lower labial segment labiolingually is altered only in specific cir-cumstances. If the lower labial segment is crowded the lower canines need to be repositioned and extractions may be needed to facilitate http://dentalebooks.com 40 6 • C L I N I C A L D E N T I S T RYthis. Next, the upper arch should be planned around the lower arch and the upper canine placed in a Class I relationship with the lower. If the canines are placed into a Class I relationship the incisors and molars should automatically fall into ideal occlusion in the majority of patients.Tooth movement. The type of tooth movement required will deter-mine the type of appliance to be used. Removable appliances are more suitable for tipping movement and fixed appliances can achieve bodily movement and correct multiple teeth simultaneously.Anchorage demands. Anchorage is the resistance to unwanted tooth movement in all three planes of space. The anchorage require-ments can be assessed by undertaking a comprehensive space analy-sis. A common scenario for anterior-posterior anchorage management is to ensure that there is adequate space for incisor retraction in Class II management. Often the maxillary first molar needs to be prevented from moving forwards to maintain space for incisor retraction. Anchorage should also be considered in the vertical and transverse dimensions.Retention. It is important that as part of informed consent, patients understand that orthodontic retention is an intergral and long-term component of orthodontic treatment. All patients have to wear their retainers, at least part-time, indefinitely, to guarantee tooth alignment.Treatment optionsA number of treatment options may be available:No appliance. It may be that, following the provision of space, spon-taneous tooth movement will occur, e.g. extraction of first premolars will allow mesially inclined canines to tip distally and give some relief of crowding in the labial segment.Removable appliances. These can be used only if simple tooth tipping alone is required.Fixed appliances. Indicated where bodily tooth movement and mul-tiple teeth need to be moved.Functional appliances. Functional appliances posture the mandible forwards to exert forces on the teeth that produce tooth movement and a small acceleration in mandibular growth. They are most com-monly used in moderate-severe Class II cases to correct a large overjet. Treatment can often be commenced in the late mixed dentition stage and is completed with a phase of fixed appliance alignment.Orthognathic surgery. If there is a significant skeletal discrepancy, successful treatment may be beyond the scope of orthodontic http://dentalebooks.com O R T h O D O N T I C S • 4 07treatment alone and require a combined orthodontic/surgical approach. This type of treatment is not usually undertaken until the late teenage years, when growth has reduced to adult levels.The prospective patient must be fully aware of the treatment plan, goals and necessary implications for him/her in terms of extractions, appliances, retention and cooperation.Management of the developing dentitionThe development of the dentition and the timing of tooth formation and eruption is discussed in Chapter 3. It is more important to under-stand the sequence of normal dental eruption (e.g. maxillary central incisors before lateral incisors) than the actual chronological ages, as there is individual variation in the latter.As part of the routine examination of children, the dentition should be assessed using the MOCDO convention as per the DHC of the IOTN described on page 397. This will permit referral of appropri-ate cases for orthodontic treatment/advice.Primary dentitionNatal teeth are teeth present at or shortly after birth. They are rare and most commonly found in the lower incisor region. They should be extracted only if they cause problems, such as feeding difficulty.Lack of space between anterior deciduous teeth just before they are shed is indicative of future crowding within the permanent dentition.Orthodontic treatment is rarely indicated during the primary den-tition stage of development. The most important consideration is maintenance of oral health and stopping digit sucking habits before the permanent central incisor teeth erupt.Early loss of deciduous teeth. There are varying opinions on the management of enforced extractions. The effect of loss of a primary tooth depends upon the age of loss, the tooth lost and the degree of inherent crowding. Early loss may result in mesial migration of posterior teeth and spreading out of crowded anterior teeth. Specifically:Early loss of deciduous incisors. Usually causes no problem; do not balance or compensate.Early loss of deciduous canines. Rarely lost through caries but may be pushed out prematurely by a permanent lateral incisor if crowded. A balancing extraction, involving extraction of the contralateral http://dentalebooks.com 40 8 • C L I N I C A L D E N T I S T RYprimary canine, can be considered to minimize any change in the centreline. Such extractions can allow some relief in anterior crowd-ing; however, they may result in greater crowding, with mesial move-ment of the posterior teeth, within the canine/premolar region when these teeth erupt.Early loss of primary molars. Space loss may occur due to extraction or unrestored cavities or poor restorations. The earlier the extraction the greater the space loss.Early loss of rst primary molars. Unilateral loss may cause a cen-treline shift. The first permanent molar and second primary molar will drift forwards leading to some space loss.Early loss of second primary molars. If lost before the first permanent molar erupts, there will be significant space loss especially within the upper arch. If lost after the first permanent molar erupts, con-sideration should be given to placing a space maintainer, particularly if there is more than 6 months until the second premolar will erupt.Space maintenance, balancing and compensatory extractionsThe natural tooth is the ideal space maintainer. Children with high caries experience are seldom suitable candidates for long-term appli-ance wear. If only one tooth is a significant problem then consider pulp therapy.Consideration should be given to compensating or balancing extractions.Balancing extraction. (same arch, opposite side), to maintain sym-metry and centreline relationships.Compensating extraction. (same side, opposite arch) to maintain inter-arch relationship.It is crucial that before extracting teeth for orthodontic purposes, radiographs are taken to determine the presence/absence and condi-tion of all teeth.Mixed dentitionA variety of problems may present. Abnormalities of tooth number, form, position and structure may affect how the dentition develops as discussed in Chapter 3. Other factors affecting development of the dentition include:Sucking habits. Possible effects include: upper incisor proclination; lower incisor retroclination; narrowing of the upper arch, which may lead to mandibular displacement and a crossbite; anterior open bite (often asymmetrical).http://dentalebooks.com O R T h O D O N T I C S • 4 09Such habits often stop spontaneously but should be encouraged to stop before the permanent central incisors erupt. The sooner the habit is stopped, the better the chance of spontaneous improvement of any associated problems. In some situations a habit deterrent appliance may be indicated.Non-palpable maxillary canines. In most patients the maxillary canines should be palpable in the buccal sulcus at the age of 9 years. If they cannot be palpated the patient should be referred to a special-ist. The position of the canines can be verified radiographically (using parallax) and if they are palatal consideration may be given to removal of the primary canine to facilitate spontaneous improve-ment in position.Traumatic loss of upper central incisor. If reimplantation is not fea-sible, initially space maintenance should be carried out and then plan long-term management.Incisors in crossbite. If corrected as early as possible, and any associ-ated mandibular displacement is eliminated, the risk of gingival damage and tooth wear is reduced. Often the upper incisor(s) can be proclined with an upper removable appliance to remove the occlusal interference leading to the mandibular displacement. Once cor-rected, assuming there is a positive overbite, correction should be stable at least in the short term.Treatment of posterior crossbite. Generally, a posterior unilateral crossbite, with a mandibular displacement on closure, should be cor-rected within the mixed dentition. Often, a simple upper removable appliance with midline expansion can be used.Skeletal problems. Any patient with a severe skeletal discrepancy should be sent for an early specialist assessment. Some forms of dis-crepancy will respond better than others to early treatment and the benefits, or otherwise, should be determined.First permanent molars of poor prognosis. The prognosis for first permanent molars should be assessed at the age of 8–9 years and if there is doubt about the long-term outlook, a specialist opinion should be sought. Often the tooth condition and dental motivation will outweigh all other factors. For the best spontaneous improve-ment, timing is critical in the lower arch and loss of first molars is usually best when the furcation of the second permanent molar is just calcifying. If crowding is present, particularly in the premolar region, this will also help spontaneous space closure. Early loss of an upper first permanent molar can lead to rapid space loss. Con-sideration needs to be given to balancing and compensating extractions.http://dentalebooks.com 41 0 • C L I N I C A L D E N T I S T RYClass I malocclusionLower incisor edges occlude with or lie below the cingulum plateau of the upper central incisors.Problems that may be encountered in Class I malocclusions include crowding, spacing (much less commonly), crossbite, open bite, impactions and bimaxillary proclination.CrowdingCause. Disproportion between tooth and arch size and/or early loss of primary molars.Dental health. Dental health impact is not as great as once thought. In general it is easier to improve tooth brushing than to align the teeth to facilitate this. Crowding causing tooth impaction may impact upon dental health by causing root resorption.Stability. Influenced by method of correction.Treatment options. Arch expansion – achieved by increasing the arch width, incisor proclination or distal molar movement; Extrac-tion of teeth – particularly in severe cases.Increase in lower incisor crowding in the mid- to late teens is common. Rarely poses any threat to long-term dental health and careful thought should be given before undertaking treatment as it will often involve fixed appliances and stability is not guaranteed.SpacingCause. Often due to missing teeth, microdontia and/or dentoalveolar disproportion. Can be small teeth in average arches or normal teeth in large arches. In adults, spacing may occur secondary to loss of periodontal support and tooth drifting.Dental health. Usually there is no adverse influence on dental health; aesthetics depends on severity.Stability. The stability of space closure is poor and requires perma-nent retention as there is a great tendency to relapse.Transverse problems – crossbitesCrossbite. Deviation from the normal buccolingual relationship. Can be local or segmental.Local crossbites. Usually caused by crowding, e.g. lower second premolar forced to erupt lingually.Segmental crossbites. Involve most teeth in a buccal segment. From the dental health standpoint, of greater importance is whether or not http://dentalebooks.com O R T h O D O N T I C S • 4 11there is an associated mandibular displacement on closure. There are three commonly presenting patterns of crossbite:Unilateral crossbite with associated displacementCause. Often due to mismatch in the arch widths and displacement into a position of maximum intercuspation resulting in a crossbite. Can be related to a thumb-sucking habit.Dental health. A mandibular displacement may be associated with temporomandibular joint dysfunction, faceting, and the develop-ment of the dentition into the displaced position. Consider intercep-tive treatment using an upper removable appliance for midline expansion.Unilateral crossbite with no displacementCause. Often a skeletal asymmetry.Dental health. Often none, if no mandibular displacement, and treat-ment seldom indicated.Bilateral crossbiteCause. Skeletal base problem (both anterior/posterior and transverse).Dental health. Usually there is no displacement and it is unlikely to affect appearance. Often accept as treatment stability doubtful. Some advocate rapid maxillary expansion.Vertical problems – open biteAnterior open bite (AOB). In occlusion, the incisors fail to contact and do not overlap in the vertical plane. May be due to digit-sucking habits, a skeletal discrepancy (e.g. increased vertical dimension), or anterior tongue posture. Frequently there is an associated tongue thrust which is usually secondary and adaptive. If associated with a digit habit it will improve, if all other factors are favourable, once the habit has ceased, although this is slow and may not be complete. Correction of an open bite due to a skeletal discrepancy almost always requires a combination of orthodontics and orthognathic surgery.Posterior open bite. Rare. Aetiology unclear and treatment stability often poor.Bimaxillary proclinationIf this is present in a Class I relationship, the upper incisors cannot be retracted without first retracting the lower incisors. Long-term stability is problematic if the lower incisor anterior-posterior position is altered, due to disruption of the soft tissue equilibrium.http://dentalebooks.com 41 2 • C L I N I C A L D E N T I S T RYClass II Division 1 malocclusionLower incisor edges lie posterior to the cingulum plateau of the upper central incisors, overjet is increased, upper incisors may be proclined or of average inclination.Occlusal featuresOverjet. The upper incisors are often proclined (digit habit, lip trap). Where upper incisors are at a more average inclination, the increased overjet is associated with a skeletal II pattern or retroclined lower incisors (due to lower lip activity, habit, lip trap).Overbite. Variable, often deep and complete.Buccal segments. Often Class II (related to the skeletal pattern).Alignment. Crowding, spacing, etc. are all possible in addition to the arch malrelationship.Skeletal featuresAnterior/posterior. Usually Class II skeletal pattern due to mandibu-lar retrognathia – the primary aetiological feature. As the severity of skeletal pattern increases, so does treatment difficulty.Vertical. Overbite will often reflect the vertical skeletal dimension although not in every case.Soft tissuesLips are often incompetent. For reasons of stability, the lower lip should lie in front of the upper incisors at rest following treatment.Mandibular position/path of closureMay tend to posture the mandible to improve profile and lip contact.Why treat?If an increased overjet is present, the incisors are at greater risk of trauma. Incompetent lips may increase this risk further. The patient may also express aesthetic concerns related to upper incisor protru-sion. Occasionally there may be an overbite problem.Treatment optionsManagement of the overjet is the key factor in treatment planning.No treatment. May be acceptable, especially if mild.Extractions only. Rarely an option. May relieve crowding but no beneficial effect on the incisor relationship.http://dentalebooks.com O R T h O D O N T I C S • 4 13Removable appliances. Historically a common approach but now rarely undertaken.Two-arch xed appliances. Frequently the most appropriate treat-ment option. Gives the ability to deal with the overjet, overbite, as well as tooth alignment. The overjet is often largely reduced by upper incisor retraction which has a space requirement. Anchorage man-agement is often critical for success of treatment.Functional appliance. A good option in patients with a large overjet (>6 mm) to reduce the anchorage requirements of subsequent fixed appliance treatment. Often needs a second phase of treatment with fixed appliances to complete treatment. If successful, functional appliance treatment may reduce the complexity/difficulty of second-phase fixed treatment.Orthognathic surgery. With a severe skeletal pattern, orthodontic treatment can only produce dentoalveolar camouflage. A combina-tion of orthodontics and surgery allows the skeletal pattern to be corrected (Chapter 14).Key factors in treatment planning. Severity of skeletal pattern: can the malocclusion be treated by orthodontic camouflage or would this have an adverse effect on the facial profile?Post-treatment stabilityControl of the upper incisors by the lower lip is of para-mount importance for stability.Class II Division 2 malocclusionThe lower incisor edges lie posterior to the cingulum plateau of the upper central incisors. The upper central incisors are retroclined, the overjet is usually reduced but can be increased and the overbite is increased.Occlusal featuresOverjet. Typically minimal but can be increased. Upper central inci-sors are retroclined. Upper lateral incisors are often proclined, mesially inclined and mesiolabially rotated. Lower incisors are often retroclined, contributing to lower incisor crowding, increased over-bite and a poor interincisal angle.Overbite. Usually increased and can be sufficiently severe to produce a traumatic bite.Buccal segments. May present with a scissors bite.http://dentalebooks.com 41 4 • C L I N I C A L D E N T I S T RYAlignment. Variable, there is often a typical arrangement of upper lateral incisors and the incisor retroclination may be associated with crowding.Skeletal featuresAnterior/posterior. Often skeletal Class I pattern or mild Class II with a reduced lower anterior facial height leading to a high lower lip line. Tendency to bimaxillary retroclination.Vertical. Usually reduced or average. May have a closing (anticlock-wise or forward) growth rotation.Transverse. If severe, results in scissors bite.Scissors biteLingual crossbite of the lower posterior teeth.Soft tissuesThe lower lip often rests high on the upper central incisor (high lip line) and the labiomental fold is often deep.Mandibular position/path of closureUsually a simple hinge closure but in severe cases a habitual down-wards and forwards posture may be seen.Why treat?Possibility of overbite trauma; aesthetics.Treatment optionsNo treatment. Especially in a mild case this is often a very sensible option.Extractions only. Rarely an acceptable option.Removable appliance. Rarely appropriate because of the interinci-sor relationship. May, however, use a removable appliance in con-junction with fixed appliance treatment to help overbite reduction by taking advantage of the bite plane effect.Two-arch xed. The vast majority of cases in this group, if treated, need upper and lower fixed appliances. This allows overbite control and, more particularly, control of the incisor inclinations – essential for long-term stability. If the incisors are retroclined it may be that the crowding can be dealt with by proclining the labial segments. This facilitates relief of crowding, overbite reduction, correction of the interincisal angle, improves the profile and may help stability.Functional appliances. An option, but must first convert the incisor relationship to Class II division 1 by upper incisor proclination. Has http://dentalebooks.com O R T h O D O N T I C S • 4 15added advantage of dealing with the overbite using the bite plane effect. Likely to need fixed appliances for completion.Orthognathic surgery. May need to consider in an adult with a sig-nificant anterior/posterior discrepancy or very reduced lower facial height. Indicated if profile poor or to reduce a very deep overbite within a non-growing patient.Post-treatment stabilityThe rotated lateral incisors have a strong tendency to relapse. Over-bite reduction stability is related to the interincisal angle achieved at the end of treatment.Class III malocclusionLower incisor edges lie anterior to the cingulum plateau of the upper central incisors. The overjet is reduced or reversed.Occlusal featuresOverjet. Often see dentoalveolar compensation of the incisors, which makes the reverse overjet seem less severe than the underlying skeletal discrepency. The upper incisors are often crowded and pro-clined. The lower incisors are frequently retroclined (to compensate for the skeletal pattern). There may be an anterior displacement on closure.Overbite. Varies considerably.Buccal segments. Upper arch is often crowded, especially if there has been early loss of deciduous molars. Lower arch is often spaced. Crossbites are common due to a discrepancy in arch width and the lower arch being positioned relatively more anterior in a Class III malocclusion.Alignment. Upper often crowded.Skeletal featuresAnterior/posterior. Often the most important factor in producing a Class III is unfavourable anterior-posterior skeletal growth. As the skeletal pattern gets more adverse so does the Class III malocclusion and the scope for successful orthodontic treatment alone. The skeletal pattern is associated with a variety of causes, e.g. retrognathic maxilla, prognathic mandible, forward position of glenoid fossa, short anterior cranial base. Usually results from a combination of these factors.Vertical. Wide variation. Anterior height of the intermaxillary space may be large and associated with an anterior open bite.http://dentalebooks.com 41 6 • C L I N I C A L D E N T I S T RYTransverse. In many cases the maxillary base is narrow and the mandibular base wide. This is further aggravated by the anterior/posterior discrepancy.Soft tissuesIncreased anterior intermaxillary height may result in incompetent lips.Mandibular position/path of closureUsually a simple hinge closure but an anterior mandibular displace-ment may be seen if there is an incisor interference. Occasionally overclosure is evident.In a Class III malocclusion growth is often a problem. The mandi-ble often grows for longer than the maxilla making the Class III problem worse. Vertical growth and the extent of overbite is impor-tant for the stability of incisor correction.Why treat?There may be functional concerns about the ability to masticate, as well as aesthetic concerns. A mandibular displacement may increase the risk of temporomandibular joint dysfunction, incisal wear and/or recession labial to the lower incisors.TreatmentKey factors in treatment planning. Concerns of patient (profile or teeth), severity of skeletal pattern (and possible growth changes). Can the patient achieve edge-to-edge incisor contact? Is there an overbite which would help to retain the correction. Amount of den-toalveolar compensation possible?No treatment. If crowding is minimal or there is no mandibular displacement, it is possible to accept and review at a later date.Extractions only. Upper arch extractions would only provide relief of crowding and not correction of the incisor relationship.Removable appliance. May be used as an interceptive measure to correct an anterior crossbite in the mixed dentition but requires an adequate overbite to maintain the correction.Single-arch xed. Could align the upper arch and accept the Class III incisor relationship.Two-arch xed. Will allow dentoalveolar correction of the malocclu-sion by upper incisor proclination and lower incisor retroclination. Requires careful consideration of the effects of unfavourable growth. May wish to delay treatment until the likely outcome of growth is more predictable. Best results are obtained where the skeletal http://dentalebooks.com O R T h O D O N T I C S • 4 17discrepancy is mild and where there is minimal dentoalveolar com-pensation already present.Functional appliances and protraction headgear. Less popular in Class III cases due to the undesirable effects of continuing growth. Protraction headgear may be appropriate in certain circumstances to encourage maxillary growth, proclination of the maxillary incisors, retroclination of the mandibular incisors and downwards and back-wards rotation of the mandible. Compliance may be problematic.Orthognathic surgery. The main option for the severe Class III malocclusion. A phase of presurgical orthodontics will be needed to decompensate and align the arches before surgery in the late teens.Post-treatment stabilityDependent upon the overbite and long-term mandibular growth.Removable appliancesAn orthodontic device which can be removed from the mouth by the patient for cleaning and eating. May be either passive or active:ActiveDesigned to achieve tooth movement (tipping) by means of active compo-nents such as wire springs and screws.PassiveAppliances designed to maintain teeth in their present position, e.g. space maintainers, retainers.This section deals with the conventional type of removable appliance used when simple tooth tipping is indicated. Most functional appli-ances are also classified as removable appliances.IndicationsUse of removable appliances requires careful case selection. They should not be used in circumstances where fixed appliance therapy would be more appropriate. They may be used as an adjunct to fixed appliance treatment.Treatment options with removable appliancesSimple tipping movement of teeth. A force applied to the crown of a tooth by a spring will cause tipping about a fulcrum roughly one-third to one-half of the way from the root apex. As the crown tips in one direction the root apex will tip in the opposite. If the use of a removable appliance to tip a tooth is being considered, assess the angulation of the tooth, its desired position and decide if it is feasible to achieve this movement with simple tooth tipping.http://dentalebooks.com 41 8 • C L I N I C A L D E N T I S T RYOverbite reduction. In cases with a deep overbite, the use of a flat anterior bite plane may help overbite reduction by holding the poste-rior teeth out of occlusion and allowing their continued eruption.Elimination of occlusal interferences and crossbite correction. Pos-terior bite planes can be used to prop the occlusion and facilitate crossbite correction by freeing the occlusion and eliminating any displacement on closure.Extrusion of teeth. (if used with a fixed appliance component) A spring can be used to apply an extrusive force if a bracket is placed to allow force delivery. The acrylic coverage of the palate provides verti-cal anchorage to resist the effect of this extrusive force.Space maintainer. A removable appliance can be used to control the position of groups of teeth while awaiting further eruption.Retainer. Removable retainers are often used after active appliance treatment.Habit deterrent. A simple removable appliance may be used, where appropriate, to help discourage a digit-sucking habit.ContraindicationsRemovable appliances are not indicated if simple tooth tipping is inappropriate, e.g. where multiple rotations or bodily tooth move-ment is required. The range of malocclusions that can be treated to a high standard with removable appliances alone is limited. Remov-able appliances should be avoided in poorly controlled epileptic patients due to the risk of appliance inhalation during seizures.Components of removable appliancesThese can be described as: retentive components; active components; baseplate.Retentive componentsRetention is the method by which the appliance resists displacement away from the oral mucosa. Good retention will help patient compli-ance, anchorage and tooth movement.Typical retentive components are:Adams’ clasp Posterior teeth – 0.7 mm hard stainless steel wire.Southend clasp Anterior teeth – 0.7 mm hard stainless steel wire.Retention is gained by engaging the undercuts of teeth. In appli-ance design the principle of three-point (or more) fixation should be adhered to.Active componentsProvide the force which moves the teeth. A variety of different methods are used, e.g. wire springs and bows, screws, elastics.http://dentalebooks.com O R T h O D O N T I C S • 4 19Springs. Springs are activated in the intended direction of move-ment and when the appliance is seated the spring is displaced. The spring then attempts to return to its original position, thereby apply-ing force to the tooth. The force applied (F) is affected by the deflection of the wire (d), radius of the wire (r) and length of the wire (l), This is expressed in the equation:Fdrl∝43Examples: palatal finger spring, buccal canine retractor, Z-spring.Points to rememberStability ratio – ideally a spring should be flexible in the desired direc-tion of action but not in others.As light a force as possible for a given deflection is desired.Coils are incorporated to increase the length within the confines of the oral cavity. The coil should unwind as the force is dissipated. Although simple in design, to be used to maximum effect careful attention to detail is needed. If poorly designed or adjusted they can cause tooth movement in the wrong direction.The force applied to a single-rooted tooth should be about 0.3 N (approx. 30 g), which, for a 0.5 mm palatal finger spring, will be about 2–3 mm of activation.A palatal finger spring should be boxed and guarded.Bows. Mechanically more complex than springs. Supported bows such as a Roberts’ retractor have good flexibility and a good stability ratio.Screws. Typical activation (one turn once or twice a week) is 0.2 mm and thus a large force is applied intermittently over a small distance.Elastics. Historically used as an alternative to a labial bow to improve the appearance, but may slide up teeth and traumatize the soft tissues. Furthermore, they tend to flatten the arch.BaseplateRemovable appliances have an acrylic baseplate. It should fit well around the teeth that are not to move and is trimmed away from those required to move. The functions of the baseplate are: to support and protect other components; to prevent unwanted drift of teeth; to contribute to anchorage. May be extended into bite planes.Flat anterior bite plane. Often used to free the occlusion or to encourage overbite reduction. At design stage, the height and length of the bite plane must be specified.http://dentalebooks.com 42 0 • C L I N I C A L D E N T I S T RYPosterior bite plane. Can be helpful in eliminating a displacement and to free the occlusion sufficiently to push a tooth over the bite. Keep to minimal thickness.The baseplate also has an important role in anchorage (p. 399). Anchorage can be:Intramaxillary from within the same arch.Intermaxillary from the opposing arch.Extraoral from outside the mouth (headgear, facemask).With a removable appliance anchorage is aided by: baseplate contact with teeth not being moved; baseplate contact with the palate; applying simple tipping forces; applying light tooth-moving forces; applying force to only a small number of teeth at any one time.Anchorage can be reinforced by use of extraoral (headgear) or intermaxillary (elastic) anchorage.Designing a removable applianceWhen designing a removable appliance remember: design for a spe-cific task; design at the chair side with the patient still in the chair; draw and describe the design on a laboratory prescription sheet; use a systematic approach: retention – activation – baseplate and any baseplate modifications; do not attempt to put too many active com-ponents on one appliance.Appliance ttingWhen tting a removable appliance:1. Check the appliance provided complies with the design and there are no sharp spicules of acrylic.2. Try the appliance in the mouth.3. Ensure it is comfortable.4. Adjust the appliance.5. Take relevant measurements to assess progress.6. Give patient instructions on:a. insertion, removal and careb. when to wearc. what to expectd. what to do if problems occur.7. Arrange next visit – usually 4–6 weeks later.Appliance check visitsAt each visit assess: tooth movement; anchorage; cooperation.A standard approach is essential at each visit to allow this informa-tion to be gathered quickly and efficiently.http://dentalebooks.com O R T h O D O N T I C S • 4 21Problems with removable appliance treatmentPotential problems are: no tooth movement; incorrect tooth move-ment; anchorage loss.1. Ask the patient how he/she is coping. This will identify any specic prob-lems and allows an assessment of speech.2. Examine the patient with the appliance in situ. Does it t? Are the active components seating correctly? Are the teeth still free to move?3. Ask the patient to remove the appliance. How does the patient handle the appliance? Does it look worn?4. Check measurements – progress of tooth movement and anchorage.5. Adjust appliance:– retention– active components– baseplate.6. Check insertion and removal.7. Revise instructions to patient.8. Review in 4 weeks.If treatment progress is slow, identify a cause as soon as possible.No tooth movementCheck at each visit – if teeth fail to move as expected check:Is the tooth free to move? Baseplate trimmed correctly; occlusal locking; retained root/other anatomical limitation.Active components adjusted correctly? Check screw turns; check springs correctly in place; springs activated at last visit.Lack of wear? Signs of non-wear are: missed appointments; broken appliances; poor speech with appliance in situ; poor fit; still active at each visit; no signs of wear on appliance/soft tissue; patient displays difficulty inserting or removing appliance.Incorrect tooth movementCheck: appliance design; position of coils; contact of active compo-nent with tooth.Anchorage lossSigns (if retracting a tooth). An increasing overjet; developing cross-bite in buccal segments; deterioration in buccal segment relationship.Action. Reduce active component force; check appliance fit, design and wear; seek further advice from a specialist orthodontist if necessary.http://dentalebooks.com 42 2 • C L I N I C A L D E N T I S T RYAdvantages of removable appliancesTip teeth efficiently; good for overbite reduction; bite planes can elimi-nate displacements/occlusal interference; tooth movements usually few and simple; less chair side time needed than with fixed appli-ances; fewer inventory problems than with fixed appliances; can remove for cleaning; good source of anchorage from baseplate.Disadvantages of removable appliancesLimited tooth movement available; limited scope in lower arch; affect speech; removable by the patient – poor compliance.Fixed appliancesAn orthodontic device in which attachments are xed to the teeth and forces are applied by archwires or auxiliaries via these attachments.ComponentsClassified as attachments (brackets or bands), archwires and auxiliaries.AttachmentsAct as a ‘handle’ to allow the application of forces to the teeth in three dimensions. Two types:Brackets. Fixed to the tooth by bonding and are used on most teeth.Bands. Cemented to the teeth; used on molars and teeth with persist-ent bracket failures.The most commonly used type of fixed appliance is the pre-adjusted edgewise appliance (also termed the Straight wire appliance). A number of different bracket systems are available on the market and differences include the material used for construction (e.g. stain-less steel, ceramic), the in-built values or prescription (e.g. Roth, Andrews, MBT) and the method of archwire ligation (e.g. self-ligation). Some manufacturers have claimed that their brackets speed up treatment but there is no evidence to suggest that these claims are true.ArchwiresThe archwire is tied to the attachments. In the early stages of treat-ment (aligning and levelling) the archwire is active. At engagement, the wire is deflected and pulls the teeth with it as it returns to its original shape. In the later stages of treatment the archwire is passive and the teeth are moved along the archwire by auxiliary forces.http://dentalebooks.com O R T h O D O N T I C S • 4 23AuxiliariesSprings or elastics. Used to apply force to the teeth.Indications for xed appliancesFixed appliances are indicated where multiple tooth movement is required, e.g. de-rotation, bodily movement, controlled space closure at extraction sites. They require a suitably trained operator and suit-ably motivated patient – excellent oral hygiene, caries controlled, desires treatment and understands the implications, i.e. 18–24 months duration, visits 4–8-weekly, brush teeth after every meal, fluoride mouthwash daily, modify diet, wear elastics/headgear if required, some discomfort, retainers at end of treatment. Even then, relapse may sometimes occur.To achieve the highest standard of care, fixed appliances are usually indicated. They are, however, demanding of patient coopera-tion. Treatment should be undertaken only when the patient fully understands the implications.If in doubt, delay and do not treat – choosing a simple compromise option may preclude full correction at a later date.Contraindications for xed appliancesPoorly motivated patient; poor dental health; operator without appropriate training in use of fixed appliances; some malocclusions may not be amenable to fixed appliance treatment, i.e. beyond the scope of orthodontics alone.Advantages of xed appliancesPrecise tooth control possible; multiple tooth movements can be made concurrently.Disadvantages of xed appliancesAesthetics; oral hygiene requirements; demanding in terms of mate-rials and operator time; breakages; anchorage control/treatment monitoring more difficult.Functional appliancesThe term functional appliance describes those appliances which engage both arches and act principally by holding the mandible away from its normal resting position, and utilize the forces of the circumoral musculature to move the teeth.http://dentalebooks.com 42 4 • C L I N I C A L D E N T I S T RYClassicationThere is no universally accepted method of classification. Most are named after their originator, e.g. Andresen, Bionator, Harvold, Frankel appliances, Clark Twin–Block.Mode of actionMost functional appliances act by utilizing one or more of the follow-ing: a forced mandibular posture, which transmits forces to the teeth and jaws; a screening effect, which can either use or relieve direct forces on the teeth from the circumoral soft tissues; bite planes which produce differential eruption.Case selectionCan be used for different types of malocclusion but most effective in Class II division 1 cases. For success, virtually full-time wear is needed. It is important to review progress carefully after 6 months and if treatment is not proceeding satisfactorily, an alternative approach should be considered.Functional appliances may be used for definitive treatment or as Phase 1 of two-phase treatment: e.g. Phase 1 to reduce the overjet, overbite and improve the sagittal arch relationship; Phase 2 to com-plete alignment using fixed appliances.Advantages of functional appliancesMay utilize growth potential; can start treatment in the mixed denti-tion; effective vertical control of increased overbite; chair side adjust-ment time is minimal.Disadvantages of functional appliancesPrecise tooth movement not possible; very dependent on patient cooperation; often need Phase 2 treatment to complete; treatment duration is often prolonged.Orthodontic management of cleft lip and palateCleft lip and palate (CLP) is the most common congenital deformity in the craniofacial region. There is a wide range of presentation ranging from bifid uvula to a complete bilateral cleft of lip and palate.Incidence (UK)Approximately 1 in 700 live births. Some ethnic variation. In white Caucasians: CLP is more common in males; unilateral clefts occur http://dentalebooks.com O R T h O D O N T I C S • 4 25more often on the left side; isolated cleft palate is more common in females.ClassicationPatients with cleft lip and palate can be divided into two distinct groups.Cleft lip ± cleft palate. Those with cleft lip and cleft palate (CL + CP), or those with cleft lip alone (CL).Cleft palate. Those with cleft palate alone.AetiologyNot fully understood. Certain cleft types show family history. Genetic predisposition may be triggered by an environmental factor. May occur in isolation or as part of a syndrome.Cleft lip and palate associated problemsMain problems in orthodontic management are tooth malalignment, especially at cleft site, lack of bone to move teeth into, and the effect on facial growth.DentalTeeth. Lateral incisor on the cleft side may be absent, diminutive, one on each side of the cleft, hypoplastic, or displaced. Central incisors may also be involved, more commonly in bilateral cases.Occlusion. Majority of occlusal problems occur secondary to surgical repair of the defect. Postoperative scarring impedes normal growth of the maxilla in all three planes of space. A Class III incisor relation-ship is often seen with posterior crossbites also present.Skeletal pattern/growth. Is usually a skeletal Class III relationship due to effect of surgical scarring and maxillary retrusion as growth proceeds. Palate repair has a more serious effect on growth than does lip repair alone. Differences are most noticeable at pubertal growth spurt.Facial deformity. Surgery can disguise with varying degrees of success (Chapter 14).Hearing. Prone to otitis media due to interruption of the normal function of the Eustachian tube.Speech. Problems with normal speech due to a combination of hearing problems, inadequate soft palate function, palatal morphol-ogy and lip morphology.Psychological. Given the above, a range of psychological problems may also be present.http://dentalebooks.com 42 6 • C L I N I C A L D E N T I S T RYManagement of cleft lip and palate problemsRequires a team-based approach as part of a centralized service in a treatment centre which is exposed to large numbers of new cases per year. Main team members include orthodontist, cleft surgeon, speech and language therapist, ENT specialist. Other disciplines involved at various stages include health visitor, oral and maxillo-facial surgeon, restorative dentist, psychologist. The GDP has an important role to play in maintaining the highest possible level of oral health.Typical stages in management1. Neonatal/first 18 months Parental counselling and introduction to the Cleft Lip and Palate Association (CLAPA). Offer feeding advice, establish preventive regimen and routine dental care. Presurgical orthopaedics (to align the displaced cleft segments) may be used in some centres. Lip repair is carried out at about 3 months (some centres within days of birth). Palate repair is carried out at 9–18 months to facilitate feeding and speech.2. Early mixed dentition Permanent incisors may erupt into linguo-occlusion. This should be corrected if feasible but may be delayed until the next phase of development.3. Mid-mixed dentition If an alveolar cleft is evident, secondary alveolar bone graft is routinely performed at age 9–10 years. Cancellous bone from the iliac crest is placed in the alveolar cleft and will:a. facilitate eruption of the permanent canineb. allow alignment of teeth adjacent to the cleftc. promote orthodontic rather than prosthodontic repaird. help stabilize the maxillary segmentse. assist closure of fistulaef. improve vestibular anatomy.4. Early permanent dentition Treatment indicated is dictated by the concerns of the patient and severity of the skeletal discrepancy. If skeletal discrepancy is not severe then conventional fixed appli-ance treatment can be carried out. A significant proportion of cleft cases will have a severe skeletal Class III pattern, the full cor-rection of which requires combined orthodontics and orthog-nathic surgery in the late teens.5. Late teens If orthognathic surgery is indicated, the Class III rela-tionship is corrected by fixed appliance treatment to decompen-sate and coordinate the dental arches prior to surgery such as a Le Fort I advancement osteotomy and a mandibu lar set-back osteotomy. A genioplasty may also be indicated.http://dentalebooks.com O R T h O D O N T I C S • 4 27Orthodontic aspects of orthognathic surgery (see also Chapter 14)Orthognathic surgery is used to correct malocclusions beyond the scope of orthodontics alone, i.e. when there is a significant skeletal discrepancy. This approach to treatment is not usually carried out until growth has reduced to adult levels in the late teens.Candidates for combined orthodontic/surgical treatment must be fully assessed at a combined clinic by an orthodontist and maxillo-facial surgeon. Treatment is highly demanding of patient coopera-tion, and careful preoperative explanation is required. Patients may have unrealistic expectations and assessment by a clinical psycholo-gist may be helpful.In most cases, orthodontic treatment using fixed appliances will be required both pre- and postoperatively.Aims of presurgical orthodonticsGeneral arch alignment; arch width correction; correction of anterior/posterior position of incisors; changes in overbite; correc-tion of centrelines; create space for segmental surgery.At this stage, the aim is to facilitate surgery and create tooth posi-tions that are likely to be stable postoperatively, rather than to obtain ‘ideal’ cuspal relationships.Fine adjustments and final tooth position are achieved postoperatively.TreatmentCommon problems requiring a combined orthodontic/orthognathic surgical approach include: severe skeletal Class II pattern; severe skel-etal Class III pattern; severe anterior open bite; transverse skeletal asymmetry; congenital craniofacial deformity.http://dentalebooks.com This page intentionally left blankhttp://dentalebooks.com