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So don't be shy! Many of our volunteers have never recorded anything before LibriVox. Thank you. This page intentionally left blank Brief contents 1 The rationale for orthodontic treatment 1 2 The aetiology and classification of malocclusion 9 3 Management of the developing dentition 17 4 Craniofacial growth, the cellular basis of tooth movement and anchorage Z.
Nelson-Moon 33 5 Orthodontic assessment S. Littlewood 53 6 Cephalometrics 73 7 Treatment planning S. Dyer 16 Retention S. Littlewood 17 Removable appliances 18 Fixed appliances 19 Functional appliances S. Littlewood 20 Adult orthodontics S. Littlewood 21 Orthodontics and orthognathic surgery S. Nelson-Moon 33 4. Littlewood 5. Littlewood 7. Littlewood 10 Class II division 2 Informed consent and relapse Retainers Adjunctive techniques used to reduce relapse Conclusions about retention 17 Removable appliances 11 Class III Dyer Littlewood It should be remembered that the figures for a particular occlusal feature or dental anomaly will depend upon the size and composition of the group studied for example age and racial characteristics , the criteria used for assessment, and the methods used by the examiners for example whether radiographs were employed.
Now that a greater proportion of the population is keeping their teeth for longer, orthodontic treatment has an increasing adjunctive role prior to restorative work. In addition, there is an increasing acceptability of orthodontic appliances with the effect that many adults who did not have treatment during adolescence are now seeking treatment.
Table 1. Ethically, no treatment should be embarked upon unless a demonstrable benefit to the patient is feasible. In addition, the potential advantages should be viewed in the light of possible risks and side-effects, including failure to achieve the aims of treatment. Appraisal of these factors is called risk—benefit analysis and, as in all branches of medicine and dentistry, needs to be considered before treatment is commenced for an individual patient Box 1.
In parallel, financial constraints coupled with the increasing costs of health care have led to an increased focus upon the cost—benefit ratio of treatment. Obviously the threshold for treatment and the amount of orthodontic intervention will differ between a system that is primarily funded by the state and one that is private or based on insurance schemes.
The decision to embark upon a course of treatment will be influenced by the perceived benefits to the patient balanced against the risks of appliance therapy and the prognosis for achieving the aims of treatment Box 1.
In this chapter we consider each of these areas in turn, starting with the results of research into the possible benefits of orthodontic treatment upon dental health and psychological well-being. However, clinical experience suggests that in susceptible children with a poor diet, malalignment may reduce the potential for natural tooth-cleansing and increase the risk of decay.
Periodontal disease The association between malocclusion and periodontal disease is weak, as research has shown that individual motivation has more impact than tooth alignment upon effective tooth brushing. Certainly, good toothbrushers are motivated to brush around irregular teeth, whereas in the individual who brushes infrequently their poor plaque control is clearly of more importance.
Nevertheless, it would seem logical that in the middle of this range that, irregular teeth would hinder effective brushing. In addition, certain occlusal anomalies may prejudice periodontal support.
Crowding may lead to one or more teeth being squeezed buccally or lingually out of their investing bone, resulting in a reduction 3 of periodontal support. This may also occur in a Class III malocclusion where the lower incisors in crossbite are pushed labially, contributing to gingival recession. Traumatic overbites can also lead to increased loss of periodontal support and therefore are another indication for orthodontic intervention see also Box 1.
Finally, an increased dental awareness has been noted in patients following orthodontic treatment, and this may be of long-term benefit to oral health. Trauma to the anterior teeth Any practitioner who treats children will confirm the association between increased overjet and trauma to the upper incisors. A systematic review found that individuals with an overjet in excess of 3 mm had more than double the risk of injury.
Overjet is a greater contributory factor in girls than boys even though traumatic injuries are more common in boys. Other studies have shown that the risk is greater in patients with incompetent lips. Masticatory function Patients with anterior open bites AOB and those with markedly increased or reverse overjets often complain of difficulty with eating, particularly when incising food.
Classically patients with AOB complain that they have to avoid sandwiches containing lettuce or cucumber. Patients with severe hypodontia also may experience problems with eating. Speech Box 1. In the main, speech is little affected by malocclusion, and correction of an occlusal anomaly has little effect upon abnormal speech. However, if a patient cannot attain contact between the incisors anteriorly, this may contribute to the production of a lisp interdental stigmatism.
Tooth impaction Unerupted teeth may rarely cause pathology Fig. Unerupted impacted teeth, for example maxillary canines, may cause resorption of the roots of adjacent teeth.
Dentigerous cyst formation can occur c Fig. Supernumerary teeth may also give rise to problems, most importantly where their presence prevents normal eruption of an associated permanent tooth or teeth. Temporomandibular joint dysfunction syndrome This topic is considered in more detail in Section 1.
Research has shown that an unattractive dentofacial appearance does have a negative effect on the expectations of teachers and employers. However, in this respect, background facial appearance would appear to have more impact than dental appearance. Therefore, some individuals are unaware of marked malocclusions, whilst others complain bitterly about very minor irregularities. The dental health component of the Index of Orthodontic Treatment Need was developed to try and quantify the impact of a particular malocclusion upon long-term dental health.
The index also comprises an aesthetic element which is an attempt to quantify the aesthetic handicap that a particular arrangement of the teeth poses for a patient. Both aspects of this index are discussed in more detail in Chapter 2. The psychosocial benefits of treatment are however countered to a degree by the visibility of appliances during treatment and their effect upon the self-esteem of the individual.
In other words a child who is being teased about their teeth will probably also be teased about braces. Some patients are very aware of mild rotations of the upper incisors, whilst others are blithely unaware of markedly increased overjets. With the increasing dental awareness shown by the public and the increased acceptability of appliances, the demand for treatment is increasing rapidly, particularly among the adult population who may not have had ready access to orthodontic treatment as children.
This has also been fuelled by the increased availability of less visible appliances including ceramic brackets and lingual fixed appliances. In addition, increased dental awareness also means that patients are seeking a higher standard of treatment result. These combined pressures place considerable strain upon the limited resources of state-funded systems of care.
As it appears likely that the demand for treatment will continue to escalate, some form of rationing of state-funded treatment is inevitable and is already operating in some countries. On average, during the course of a conventional 2-year fixed-appliance treatment around 1 mm of root length will be lost this amount is not clinically significant.
However, this mean masks a wide range of individual variation, as some patients appear to be more susceptible and undergo more marked root resorption. Evidence would suggest a genetic basis in these cases.
Box 1. Avoid moving teeth out of alveolar bone Root resorption Avoid treatment in patients with resorbed, blunted, or pipette-shaped roots Loss of vitality If history of previous trauma to incisors, counsel patient Relapse Avoidance of unstable tooth positions at end of treatment Fig. Retention 1. This normally reduces or resolves following removal of the appliance, but some apical migration of periodontal attachment and alveolar bony support is usual during a 2-year course of orthodontic treatment.
In most patients this is minimal, but if oral hygiene is poor, particularly in an individual susceptible to periodontal disease, more marked loss may occur. Removable appliances may also be associated with gingival inflammation, particularly of the palatal tissues, in the presence of poor oral hygiene.
The presence of a fixed appliance predisposes to plaque accumulation as tooth cleaning around the components of the appliance is more difficult. Demineralisation during treatment with fixed appliances is a real risk, with a reported prevalence of between 2 and 96 per cent see Chapter 18, Section Teeth which have undergone a previous episode of trauma appear to be particularly susceptible, probably because the pulpal tissues are already compromised.
This has several aspects. This is considered in more detail in Chapter 7 but, in brief, tooth movement is only feasible within the constraints of the skeletal and growth patterns of the individual patient. The wrong treatment plan, or failure to anticipate adverse growth changes, will reduce the chances of success.
In addition, the probable stability of the completed treatment needs to be considered. If a stable result is not possible, do the benefits conferred by proceeding justify prolonged retention, or the possibility of relapse?
A successful outcome is dependent upon patient compliance with attending appointments, looking after their teeth and appliance and with wearing auxiliaries e. A patient is more likely to co-operate if they fully understand the process and their role in it from the outset i.
The likelihood of gain is reduced if the malocclusion is mild and treatment is undertaken by an inexperienced operator. In essence, it may be better not to embark on treatment at all, rather than run the risk of failing to achieve a worthwhile improvement Table 1. The debate has been particularly heated regarding the role of orthodontics, with some authors claiming that orthodontic treatment can cause TMD, whilst at the same time others have advocated appliance therapy in the management of the condition.
There are a number of factors that have contributed to the confusion surrounding TMD. The objective view is that TMD comprises a group of related disorders of multifactorial aetiology. Psychological, hormonal, genetic, traumatic, and occlusal factors have all been implicated. Recent research has shown that depression, stress and sleep disorders are major factors in the aetiology of TMD.
It is also accepted that parafunctional activity, for example bruxism, can contribute to muscle pain and spasm. Success has been claimed for a wide assortment of treatment modalities, reflecting both the multifactorial aetiology and the self-limiting nature of the condition. Given this, it is wise to try irreversible approaches in the first instance.
The reader is directed to look at two recent Cochrane reviews see Relevant Cochrane reviews and Further reading on the use of stabilization splints and occlusal adjustment. In contrast, controlled longitudinal studies have indicated a trend towards a lower incidence of the symptoms of TMD among post-orthodontic patients compared with matched groups of untreated patients. If this were the case, then given the high incidence of malocclusion in the population 50—75 per cent , one would expect a higher prevalence of TMD.
A number of carefully controlled longitudinal studies have been carried out in North America, and these have found no relationship between the signs and symptoms of TMD and the presence of non-functional occlusal contacts or mandibular displacements.
However, other studies have found a weak association between TMD and some types of malocclusion including Class II skeletal pattern especially associated with a retrusive mandible ; Class III; anterior open bite; crossbite and asymmetry.
It is important to advise patients of this, particularly those who present reporting TMD symptoms, and to note this in their records. Whilst current evidence indicates that orthodontic treatment is not a contributory factor and also does not cure the TMD, it is advisable to carry out a TMD screen for all potential orthodontic patients.
At the very least this should include questioning patients about symptoms; an examination of the temporomandibular joint and associated muscles and recording the range of opening and movement see Chapter 5. If signs or symptoms of TMD are found then it may be wise to refer the patient for a comprehensive assessment and specialist management before embarking on orthodontic treatment. The temporomandibular joint and orthodontics 7 Relevant Cochrane reviews: Occlusal adjustment for treating and preventing temporomandibular joint disorders Koh, H.
Occlusal adjustment cannot be recommended for the management or prevention of TMD. Stabilisation splint therapy for temporomandibular pain dysfunction syndrome. Al-Ani, M. Principal sources and further reading American Journal of Orthodontics and Dentofacial Orthopedics, 1 , This is a special issue dedicated to the results of several studies set up by the American Association of Orthodontists to investigate the link between orthodontic treatment and the temporomandibular joint.
Chestnutt, I. The orthodontic condition of children in the United Kingdom, British Dental Journal, , — Davies, S. Orthodontics and occlusion. This concise article is part of a series of articles on occlusion. It contains an example of an articulatory examination. Egermark, I. A year follow-up of signs and symptoms of temporomandibular disorders in subjects with and without orthodontic treatment in childhood. Angle Orthodontist, 73, — A long-term cohort study which found no statistically-significant difference in TMD signs and symptoms between subjects with or without previous experience of orthodontic treatment.
Holmes, A. The subjective need and demand for orthodontic treatment. British Journal of Orthodontics, 19, — Joss-Vassalli, I. Orthodontic therapy and gingival recession: a systematic review. Orthodontics and Craniofacial Research, 13, — Luther, F. TMD and occlusion part I. Damned if we do? Occlusion the interface of dentistry and orthodontics.
British Dental Journal, 13, TMD and occlusion part II. Functional occlusal problems: TMD epidemiology in a wider context. These 2 articles are well worth reading. Maaitah, E. Factors affecting demineralization during orthodontic treatment: A post-hoc analysis of RCT recruits. American Journal of Orthodontics and Dentofacial Orthopedics, , — A useful study which concludes that pre-treatment age, oral hygiene and status of the first permanent molars can be used as a guide to the likelihood of decalcification occurring during treatment.
Mizrahi, E. Risk management in clinical practice. Part 7. Dento-legal aspects of orthodontic practice. Murray, A. Discontinuation of orthodontic treatment: a study of the contributing factors.
British Journal of Orthodontics, 16, 1—7. Nguyen, Q. A systematic review of the relationship between overjet size and traumatic dental injuries. European Journal of Orthodontics, 21, — Office for National Statistics Office for National Statistics, London.
Shaw, W. British Dental Journal, , 33—7. A rather pessimistic view of orthodontics. Root resorption associated with orthodontic tooth movement: a systematic review.
Wheeler, T. Orthodontic treatment demand and need in third and fourth grade schoolchildren. American Journal of Orthodontics and Dentofacial Orthopedics, , 22— Contains a good discussion on the need and demand for treatment. An interesting and informative read on decalcification during orthodontic treatment.
References for this chapter can also be found at: www. At a basic level, malocclusion can occur as a result of genetically determined factors, which are inherited, or environmental factors, or more commonly a combination of both inherited and environmental factors acting together. For example, failure of eruption of an upper central incisor may arise as a result of dilaceration following an episode of trauma during the deciduous dentition which led to intrusion of the primary predecessor — an example of environmental aetiology.
However, if in the latter example caries an environmental factor has led to early loss of many of the deciduous teeth then forward drift of the first permanent molar teeth may also lead to superimposition of the additional problem of crowding.
While it is relatively straightforward to trace the inheritance of syndromes such as cleft lip and palate see Chapter 22 , it is more difficult to determine the aetiology of features which are in essence part of normal variation, and the picture is further complicated by the compensatory mechanisms that exist.
Evidence for the role of inherited factors in the aetiology of malocclusion has come from studies of families and twins. The facial similarity of members of a family, for example the prognathic mandible of the Hapsburg royal family, is easily appreciated.
However, more direct testimony is provided in studies of twins and triplets, which indicate that skeletal pattern and tooth size and number are largely genetically determined. Examples of environmental influences include digit-sucking habits and premature loss of teeth as a result of either caries or trauma. Soft tissue pressures acting upon the teeth for more than 6 hours per day can also influence tooth position.
However, because the soft tissues including the lips are by necessity attached to the underlying skeletal framework, their effect is also mediated by the skeletal pattern. Crowding is extremely common in Caucasians, affecting approximately two-thirds of the population. As was mentioned above, the size of the jaws and teeth are mainly genetically determined; however, environmental factors, for example premature deciduous tooth loss, can precipitate or exacerbate crowding.
In evolutionary terms both jaw size and tooth size appear to be reducing. However, crowding is much more prevalent in modern populations than it was in prehistoric times. It has been postulated that this is due to the introduction of a less abrasive diet, so that less interproximal tooth wear occurs during the lifetime of an individual. However, this is not the whole story, as a change from a rural to an urban life-style can also apparently lead to an increase in crowding after about two generations.
Although this discussion may at first seem rather theoretical, the aetiology of malocclusion is a vigorously debated subject. This is because if one believes that the basis of malocclusion is genetically determined, then it follows that orthodontics is limited in what it can achieve.
However, the opposite viewpoint is that every individual has the potential for ideal occlusion and that orthodontic intervention is required to eliminate those environmental factors that have led to a particular malocclusion. Research suggests that for the majority of malocclusions the aetiology is multifactorial with polygenic inheritance, and orthodontic treatment can effect only limited skeletal change.
When planning treatment for an individual patient it is often helpful to consider the role of the following in the aetiology of their malocclusion. Further discussion of these factors will be considered in the forthcoming chapters covering the main types of malocclusion: 1 Skeletal pattern — in all three planes of space 2 Soft tissues 3 Dental factors Of necessity, the above is a brief summary, but it can be appreciated that the aetiology of malocclusion is a complex subject, much of which is still not fully understood.
The reader seeking more information is advised to consult the publications listed in the section on Further reading. Box 2. In addition, classifications and indices allow the prevalence of a malocclusion within a population to be recorded, and also aid in the assessment of need, difficulty, and success of orthodontic treatment.
Malocclusion can be recorded qualitatively and quantitatively. However, the large number of classifications and indices which have been devised are testimony to the problems inherent in both these approaches. All have their limitations, and these should be borne in mind when they are applied Box 2. The main drawback to a qualitative approach is that malocclusion is a continuous variable so that clear cut-off points between different categories do not always exist.
This can lead to problems when classifying borderline malocclusions. In addition, although a qualitative classification is a helpful shorthand method of describing the salient features of a malocclusion, it does not provide any indication of the difficulty of treatment. Qualitative evaluation of malocclusion was attempted historically before quantitative analysis.
One of the better known classifications Box 2. Angle described three groups Fig. The categories defined by British Standard are shown in Box 2. Some workers have suggested introducing a Class II intermediate category for those cases where the upper incisors are upright and the overjet increased to between 4 and 6 mm.
However, this suggestion has not gained widespread acceptance. In practice discrepancies of up to half a cusp width either way were also included in this category. This is also known as a postnormal relationship. This is also known as a prenormal relationship. It is popular in America, particularly for research purposes.
Good reproducibility has been reported and it has also been employed to determine the success of treatment with acceptable results. The index scores nine defined parameters including molar relationship, overbite, overjet, posterior crossbite, posterior open bite, tooth displacement, midline relation, maxillary median diastema, and absent upper incisors.
Allowance is made for different stages of development by varying the weighting applied to certain parameters in the deciduous, mixed, and permanent dentition. There are two subdivisions of this category: Division 1 — the upper central incisors are proclined or of average inclination and there is an increase in overjet.
Division 2 — The upper central incisors are retroclined. The overjet is usually minimal or may be increased. The overjet is reduced or reversed. It comprises two elements. Dental health component This was developed from an index used by the Dental Board in Sweden designed to reflect those occlusal traits which could affect the function and longevity of the dentition. The single worst feature of a malocclusion is noted the index is not cumulative and categorized into one of five grades reflecting need for treatment Table 2.
Scores are recorded for a number of parameters listed below , before and at the end of treatment using study models. Unlike IOTN, the scores are cumulative; however, a weighting is accorded to each component to reflect current opinion in the UK as to their relative importance.
A high standard of treatment is indicated by a mean percentage reduction of greater than 70 per cent. A change of 30 per cent or less indicates that no appreciable improvement has been achieved. The size of the PAR score at the beginning of treatment gives an indication of the severity of a malocclusion. Obviously it is difficult to achieve a significant reduction in PAR in cases with a low pretreatment score. Overbite Aesthetic component This aspect of the index was developed in an attempt to assess the aesthetic handicap posed by a malocclusion and thus the likely psychosocial impact upon the patient — a difficult task see Chapter 1.
The aesthetic component comprises a set of ten standard photographs Fig. Colour photographs are available for assessing a patient in the clinical situation and black-andwhite photographs for scoring from study models alone. The aesthetic 2. A score of more than 43 is said to indicate a demonstrable need for treatment. Following treatment the index is scored again to give an improvement grade and thus the outcome of treatment.
Grade 5 Very Great 5a Increased overjet greater than 9 mm 5h Extensive hypodontia with restorative implications more than one tooth missing in any quadrant requiring pre-restorative orthodontics 5i Impeded eruption of teeth with the exception of third molars due to crowding, displacement, the presence of supernumerary teeth, retained deciduous teeth, and any pathological cause 5m Reverse overjet greater than 3.
All rights reserved. A preliminary evaluation of an illustrated scale for rating dental attractiveness. European Journal of Orthodontics, 9, —8. He found six features, which are described in Box 2.
These six keys are not a method of classifying occlusion as such, but serve as a goal. Occasionally at the end of treatment it is not possible to achieve a good Class I occlusion — in such cases it is helpful to look at each of these features in order to evaluate why. Andrews used this analysis to develop the first pre-adjusted bracket system, which was designed to place the teeth in three planes of space to achieve his six keys see Box 2.
For further details of pre-adjusted systems see Chapter The distobuccal cusp of the upper first molar contacts the mesiobuccal cusp of the lower second molar Correct crown angulation: all tooth crowns are angulated mesially Correct crown inclination: incisors are inclined towards the buccal or labial surface.
Buccal segment teeth are inclined lingually. In the lower buccal segments this is progressive No rotations No spaces Flat occlusal plane Principal sources and further reading Andrews, L. The six keys to normal occlusion. American Journal of Orthodontics, 62, — Peer Assessment Rating : reliability and validity.
European Journal of Orthodontics, 14, — Angle, E. Classification of malocclusion. Dental Cosmos, 41, — The PAR index, part 1.
British Standards Institute Daniels, C. Journal of Orthodontics, 27, — Harradine, N. The effect of extraction of third molars on late lower incisor crowding: A randomized controlled clinical trial.
British Journal of Orthodontics, 25, — Markovic, M. At the crossroads of oral facial genetics. Mossey, P. The heritability of malocclusion. British Journal of Orthodontics, 26, —13, — Proffit, W. Equilibrium theory revisited: factors influencing position of the teeth. Angle Orthodontist, 48, — Further reading for those wishing to learn more. Richmond, S. The PAR index Peer Assessment Rating : methods to determine the outcome of orthodontic treatment in terms of improvements and standards.
European Journal of Orthodontics, 14, —7. The PAR index, part 2. Discover over 2, journals, 48, books, and many iconic reference works.
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