Treatment planning

16 May

Treatment planning
7.1. INTRODUCTION
Without doubt, treatment planning is the most difficult, but also the most important, element of orthodontics. A knowledge of dental development, facial growth, psychology, and appliance mechanics are all prerequisites for success. Whilst much can be learnt from textbooks there is no substitute for clinical experience gained over time. Therefore, when in doubt, the less experienced should refer the patient to a specialist for advice.
Prior to planning treatment a thorough examination of the patient and their malocclusion should be carried out (Chapter 5). As soon as practicable after this assessment, the patient’s records, including study models and radiographs, should be studied, preferably during a quiet period away from the clinical environment.
7.2. PATIENT MOTIVATION
In order for orthodontic treatment to be successful the patient’s willing participation and cooperation are essential. Therefore time spent on assessing a patient’s concerns regarding the alignment of their teeth and their motivation towards appliance treatment is never wasted. It may be wiser to achieve a compromise result successfully than to fail to complete an ideal treatment plan. In this respect it is important to counsel the patient regarding their role in the success of treatment. If motivation is at all in doubt, it is wiser not to proceed or at least to ‘test the water’ with a simple appliance before any irreversible steps, for example extractions, are undertaken. On occasion, a patient will seek perfection but will be unwilling to cooperate fully with the type of appliance necessary to achieve this. Faced with this situation, the wise clinician will not proceed.
7.3. LIMITATIONS OF ORTHODONTIC TREATMENT
When planning treatment the limitations of orthodontic appliances should be borne in mind. With an enthusiastic patient and favourable growth (which is more likely in children and in Class II rather than Class III malocclusions) compensation of moderately severe skeletal patterns can be achieved with functional and/or fixed appliances. However, where growth is likely to be unfavourable and/or the underlying skeletal pattern is severe, consideration should be given to using a combined surgical and orthodontic approach (see Chapter 20).
Conventional removable appliances (Chapter 16) are only suitable for malocclusions where tipping movements will suffice. Functional appliances (Chapter 18)

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are particularly useful in the management of Class II malocclusions in a growing patient.

7.4. TIMING OF TREATMENT
In the vast majority of cases definitive orthodontic treatment is best carried out in the early permanent dentition. The reasons for this include the following:
  • Growth can be utilized to facilitate anteroposterior arch correction and overbite reduction.
  • The tendency for spontaneous tooth movement is greatest during and shortly after tooth eruption, and while the patient is still growing.
  • Active tooth movement cannot begin until after eruption.
  • Patient cooperation reaches a peak in the early teens, but diminishes rapidly from around 14–15 years.
  • Cellular reactions and bone remodelling in response to orthodontic forces are more rapid in children.
Orthodontic treatment is possible in adulthood but the range of malocclusions that can be tackled by orthodontics alone is diminished because of a lack of growth. In addition, tooth movement is initially slower than in children. Root resorption during treatment has been found to occur to a greater extent in adults. Nevertheless, once they have made the decision to go ahead with orthodontic treatment, adults usually make conscientious and cooperative patients.
7.5. AIMS OF TREATMENT
The first step in the planning process is to decide whether or not treatment is indicated. This issue has been discussed in detail in Chapter 1. In summary, appliances and/or extractions should only be embarked upon when a significant improvement in dental health or aesthetics can be achieved. It is better not to proceed than to run the risk of worsening a patient’s occlusion or appearance.
Once it has been decided that treatment is indicated, consideration should be given to the aims of treatment. This involves visualizing the finished result and then evaluating what occlusal changes are required to achieve this. It is advisable to decide what the ideal aims should be and then, if necessary, to modify them in the light of other considerations such as patient cooperation. However, it is important to note in the patient’s records any treatment plans discussed and why a particular set of treatment aims was finally selected.
When deciding upon the aims of treatment the less experienced operator may find it helpful to construct a brief summary of the patient’s malocclusion (see Chapter 5, Section 5.9). This gives a ‘problem list’ from which those factors that are to be corrected can be selected. However, a logical approach is required. For example, of the two plans below, plan B is preferable as this is the sequence which practical treatment would take.
Plan A
  • Reduction of overjet.
  • Correction of crossbite 5.
  • Relief of crowding.
  • Reduction of overbite.

Fig. 7.1. Patient HW aged 12 years: (a)–(e) pretreatment; (f)–(j) post-treatment. HW had a Class II division 1 malocclusion on a Class II skeletal pattern with crowding. As proclination of the lower labial segment had helped to compensate for the Class II skeletal pattern, this malocclusion was treated by extraction of all four first premolars and upper removable appliances. Anchorage was reinforced with extra-oral anchorage.

Treatment planning

Plan B
  • Relief of crowding.
  • Reduction of overbite.
  • Correction of crossbite ⊥5.
  • Reduction of overjet.
It is important to remember that the planning process is flexible and that the initial aims selected may have to be re-evaluated and revised.
7.6. PRINCIPLES OF TREATMENT PLANNING
The approach to treatment planning outlined below will provide a logical basis for the management of most malocclusions (Fig. 7.1). However, this section should be read in conjunction with Chapters 8, 9, 10, 11, 12, 13, 14, 15 for a fuller appreciation of management.
Mixed dentition problems are covered separately in Chapter 3.
7.6.1. The lower arch (Fig. 7.2)
It is accepted that in the majority of patients the lower labial segment lies in a zone of balance between the tongue and the cheeks. There are exceptions to this rule (see Chapter 10), but the management of such cases is the domain of the specialist and it is advisable for the inexperienced operator to consider the labiolingual position of the lower incisors as immutable. This precept has the advantage of providing a starting point around which treatment planning can be based.
The first step is to assess the alignment, including the presence of crowding or spacing, of the lower arch. If alignment is good or acceptable, then attention can be turned to the upper arch (Section 7.6.2). If the lower labial segment is either actually crowded, or crowding is expected following eruption of the canines (potential crowding), both the degree of crowding and the likelihood of its increasing significantly need to be considered. Once intercanine growth has slowed, at around 9 years of age, crowding of the lower labial segment is likely to increase, particularly if third permanent molars are developing and/or the patient is still actively growing. With practice the degree of crowding can often be assessed by eye. The less experienced may find it helpful to measure the arch circumference (from the mesial surface of the first permanent molars around the arch through the contact points) and compare this with the actual widths of the permanent teeth (Fig. 7.3).
Fig. 7.3. (a) Arch circumference measured from the mesial aspect of the first permanent molars by means of the best fit through the contact points around the arch. A flexible piece of wire (for example copper or fuse wire) should be used. (b) The widths of each individual tooth (anterior to the first molars) are measured using dividers. Each dimension is indented onto a ruled line on a piece of paper to give the space required to accommodate all the teeth anterior to the first permanent molars in alignment. (c) Comparison of the sum total of the combined widths with the actual space available (the arch circumference) gives an exact measurement of the crowding present.
If the crowding is very mild it may be wiser to accept this. If mid-arch extractions are carried out, residual spacing may remain or if if fixed appliances are used to try and close any residual space, some lingual retraction of the incisors may occur which is generally undesirable.
If the overbite is increased, account must also be taken of the space required to level the curve of Spee. An averagely increased curve of Spee will require approximately a quarter unit of space for leveling.
Planning space requirements is discussed in greater detail in Section 7.7. In summary, space can be provided by the following manoeuvres:
  • distal movement of the molars, which is commonly considered for the upper arch but very rarely in the lower arch;
  • expansion;
  • extractions (see Section 7.7.1), which is the most commonly used approach.
Once relief of crowding, if indicated, has been decided upon, the next step in the treatment planning process is to consider what tooth movements are required to align the lower arch. Spontaneous tooth movements are greatest as the teeth are erupting in growing patients but cannot be relied upon to produce complete alignment. Changes are greatest for the first 6 months following relief of crowding.
Mesially inclined canines and lingually inclined lower premolars will usually become upright if space is made available provided that there are no occlusal interferences, although this occurs less readily in an older patient who is not growing. If the canines are distally inclined or any teeth are rotated, fixed appliances are usually required to achieve satisfactory alignment. Also, if extraction of the second premolars or first molars is indicated, fixed appliances are usually necessary to achieve alignment and to close space by bodily movement (Section 7.7.1).
If there is a centreline discrepancy in a crowded lower arch, some spontaneous correction may be achieved by staggering the extractions. However, if the discrepancy is greater than half a tooth width, complete correction is unlikely and fixed appliances will be required if the centrelines are to be coordinated.
Treatment planning
Fig. 7.4. Upper arch of HW showing mild crowding. It was decided to extract both upper first premolars to provide space for retraction of upper canines into Class I relationship with the corrected position of lower canines.
7.6.2. The upper arch (Fig. 7.4)
Once alignment of the lower arch has been planned, it is often helpful to envisage the anticipated position of the lower canine before focusing on building the upper arch around the lower arch. The first step in this process is mentally to reposition the maxillary canine into a Class I relationship with the lower canine. This will not only give an indication of whether space has to be created, but will also indicate the amount and type of movement required. Allowance should be made for spacing of the lower labial segment, if present, and for tooth-size discrepancies, for example peg-shaped lateral incisors.
If the aim of the treatment is to produce a Class I incisor and molar relationship, then in most cases with crowding it is usual to plan to extract the same tooth in the upper arch as is planned in the mandibular arch. This makes coordination of space closure and appliance mechanics between the arches considerably easier. The major exceptions to this rule occur when extractions are planned to aid dento-alveolar compensation in malocclusions with a skeletal component. For example, in Class II malocclusions extractions in the upper arch alone leading to a Class II buccal segment relationship may be indicated if the lower arch is well aligned, or extraction of the first premolars in the upper arch may be

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matched by the extraction of the second premolars in the lower arch to alter the anchorage balance (see Chapters 9 and 10).

The tooth movements needed to align the upper labial segment, and therefore the type of appliance required, should be considered in conjunction with correction of the incisor relationship.
Fig. 7.5. Correction of HW’s incisor relationship required reduction of the overbite and then the overjet. As proclination of the lower incisors had helped to compensate for the mild Class II skeletal pattern, reduction of the overjet by tipping the upper incisors palatally was feasible. An upper removable appliance with a flat anterior bite plane and canine retraction springs was prescribed. A second appliance was used for overjet reduction once the overbite had been reduced and the upper canines retracted into a Class I relationship with the lower arch.
7.6.3. Correction of the incisor relationship (Fig. 7.5)
Correction of Class II divisions 1 and 2, and Class III incisor relationships are discussed in greater detail in Chapters 9, 10, and 11. Functional appliances are most useful in the correction of Class II malocclusions in the growing patient. If bodily, de-rotation, intrusion, or extrusion movements are required, fixed appliances are indicated.
It is also important to consider the incisor relationship in the vertical dimension, i.e. overbite. This is particularly pertinent in Class II malocclusions, where the overbite is increased, and in Class III malocclusions where proclination of the upper incisors alone will reduce the overbite and the chances of stability of the corrected incisor relationship.
7.6.4. The buccal segments (Fig. 7.6)
Once the labial segments have been planned, attention should be focused on the buccal segments and the molar relationship. If no extractions are planned, no teeth are congenitally absent, or matched extractions in both arches are indicated, the molar relationship at the end of treatment should be Class I. If extractions are carried out in the upper arch only, the buccal segments should be Class II; conversely, if only lower arch extractions are planned, a Class III molar relationship should result.
It is important to consider how the desired molar relationship will be achieved. Following loss of the lower second deciduous molar, the first permanent molar will drift mesially into the leeway space, but apart from this little spontaneous change can be anticipated. Therefore if correction of the buccal segment relationship is desirable, active change using appliances is necessary. Methods of changing the molar relationship include the following:
  • intramaxillary forces (for example space closure with a fixed appliance);
  • intermaxillary forces (for example Class II elastic traction or a functional appliance);
  • extra-oral traction;
  • anchorage loss, although by definition this is molar movement in an undesirable direction.
7.6.5. Anchorage
This topic is considered in more detail in Chapter 15. However, during treatment planning it may be helpful to view it in terms of the balance between the available space and the desired tooth movements. Consideration of the amount of space and the type of movement required to achieve alignment and/or correction of the incisor relationship in the steps above will give an indication of the anchorage requirements of a particular malocclusion. Obviously, if most or all of the space created by extractions is needed to retract the canines and align the incisors, no forward movement of the buccal segment teeth can be permitted and

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anchorage will have to be reinforced (see Chapter 15). In addition, the effect of the type of tooth movement required on anchorage must be taken into consideration. For example, bodily retraction of the upper incisors to reduce an increased overjet will place a greater strain on anchorage than tipping movements (i.e. the former will tend to drag the molars mesially).

It has been observed that space closure occurs more rapidly in patients with increased vertical skeletal proportions than in those with reduced vertical proportions. In practice this means that anchorage loss following extractions is more likely to be a problem in the patient with a tendency to a vertical growth pattern.
The effect of any planned tooth movement upon the patient’s facial profile also needs to be estimated. Closure of spacing (either present before treatment or created by extractions) will have the effect of retracting the anterior teeth and moving the buccal segment teeth forwards. The extent to which one of these predominates within each arch should be determined during treatment planning, as should the actual mechanics of appliance therapy necessary. Where retraction of the anterior teeth would be detrimental to the profile, specialist advice should be sought before extractions are carried out.
7.6.6. Retention
It is imperative that retention is considered at the treatment planning stage and presented to the patient as a vital part of the overall treatment package. Treatment should always aim to leave the teeth in a stable position on completion, but a period of retention is necessary to allow consolidation of newly formed bone, remodelling of the periodontal fibres, and soft tissue adaptation. Permanent retention is occasionally required, but such cases should be the province of the specialist.
Retention is discussed in more detail in Chapter 15 and also in Chapters 8, 9, 10, 11, 12, 13 in relation to the correction of each type of malocclusion. In general, a regime of at least 3 months full-time wear and then 3 months nights-only wear is advisable following treatment with removable appliances. Most operators double the time period following treatment with fixed appliances.
7.6.7. Potential pitfalls
Consideration should be given to referring a patient for specialist advice where any doubt exists or if any of the following features are noted:
  • marked skeletal discrepancies in the anteroposterior, vertical, or transverse dimension;
  • deep overbite associated with reduced vertical skeletal proportions;
  • the molar relationship is a full unit Class II and the lower arch is crowded;
  • Class II division 1 malocclusions where the overjet is greater than 10 mm and/or the overjet is increased and the upper incisors are upright;
  • first permanent molars of poor prognosis and a Class II or Class III incisor relationship;
  • asymmetrical crowding;
  • generalized spacing which concerns the patient.
7.7. CREATING SPACE
Space to relieve crowding and/or to compensate for a skeletal discrepancy can be gained by the following procedures:

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  • extractions
  • expansion
  • distal movement of the buccal segment teeth
  • reduction of tooth width
  • a combination of any or all of the above.
7.7.1. Extractions
Before planning the extraction of any permanent teeth it is important to ensure that all remaining teeth are present and developing in a satisfactory position. The factors governing the choice of teeth for extraction include the following:
  • Prognosis.
  • Position.
  • Amount of space required and where. Provided that relief of crowding only is indicated, the following is a general guide: 1–2 mm per quadrant, first pre-molar extractions should be avoided and a specialist opinion sought; 3–5 mm per quadrant, often indicates premolar extractions; more than 5 mm per quadrant, extractions and space maintenance, or even the extraction of more than one tooth per quadrant, may be necessary.
  • The incisor relationship (see Chapters 8, 9, 10, 11).
  • Anchorage requirements and desired buccal segment relationship at the end of treatment.
  • Appliances to be used.
  • Patient’s profile.
If extractions are required in both arches, forward movement of the buccal segments to close space spontaneously will be facilitated if the same tooth is removed in both the maxilla and the mandible. This is less important if fixed appliances are to be used, and indeed extracting further forward in the upper arch in Class II and in the lower arch of Class III malocclusions may aid in the correction of skeletal discrepancies.
The position of the tooth being extracted within the arch will affect the anchorage balance between the teeth anterior and posterior to the extraction site. This means that extraction of first premolars will give greater space for alignment and/or retraction of the incisors than extraction of second pre-molars, which in turn provides more space than extraction of first molars, and so on.
Fig. 7.10. Residual spacing in a patient with mild crowding who had all four first premolars removed.
In the upper arch the first premolars usually erupt prior to the maxillary canine and maximum spontaneous improvement in the position of this tooth can be achieved if the first premolar is extracted just before its emergence. However, if space is at a premium, a space maintainer should be fitted first.
If the crowding is mild, extraction of first premolars may result in residual spacing. If fixed appliances are then used to close the remaining space, there is a danger of over-retracting the labial segments, which may have deleterious effects upon the profile. In cases with mild crowding, consideration should be given to extracting teeth further distal in the arch (Fig. 7.10).
Second premolars
The indications for extraction of second premolars include the following:
  • congenital absence of the second premolars and crowding of the arch;
  • hypoplasia of the second premolars and crowding of the arch;
  • severe displacement of the second premolar;
  • mild to moderate crowding (2–4 mm per quadrant);
  • where space closure by forward movement of the molars rather than retraction of the labial segments is indicated.
Extraction of the second premolars is preferable to extraction of the first premolars in cases with mild to moderate crowding as their extraction alters the anchorage balance, favouring space closure by forward movement of the molars. In order to facilitate this and to ensure a satisfactory contact between the first premolar and the first molar, fixed appliances are required, particularly in the lower arch.
Early loss of the second deciduous molars can result in crowding of the second premolars palatally in the upper arch and lingually in the lower arch (Fig. 7.11). In the upper arch extraction of the displaced second premolars on eruption is often indicated. Conversely, in the lower arch extraction of the first premolars is usually easier and in most cases uprighting of the second premolars occurs spontaneously following relief of crowding.
Fig. 7.11. The model on the left (patient HW) shows lingual crowding of the lower second premolars. The model on the right illustrates the improvement that occurred in the position of the lower second premolars following extraction of the first premolars (see also Fig. 7.2).
First permanent molars
First permanent molars are never an orthodontist’s first choice. However, their extraction may be indicated if their prognosis is compromised to such an extent that they are unlikely to last for a reasonable time. Extraction of the first permanent molars is discussed in greater detail in Chapter 3.
Second permanent molars
Extraction of second permanent molars has become more popular in recent years. Concern raised by some practitioners about the ‘deleterious’ effect upon the profile of premolar extractions (see Section 7.8) has led to a fashionable revival of ‘non-extraction’ treatment. This term is confusing because in many such cases second permanent molars are extracted as part of the treatment.
Indications for extraction of second permanent molars include the following:
  • facilitation of distal movement of the upper buccal segments;
  • relief of mild lower premolar crowding;

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  • provision of additional space for the third permanent molars and thus reduction of the likelihood of their impaction;
  • prevention of lower labial segment crowding.
Fig. 7.12. Patient with mild lower arch crowding who had both lower second molars removed in an attempt to prevent a further increase in crowding: (a) DPT radiograph prior to extraction of both lower second molars (the upper second molars were not extracted because of concerns over the prognosis for the upper first molars); (b) DPT radiograph two years after the extractions showing eruption of both lower third molars.
Because of the greater tendency for mesial drift in the upper arch, extraction of second permanent molars will not provide space for the relief of premolar or labial segment crowding without using appliances. Timing of the extraction of second molars in the upper arch is less critical than in the lower arch, and generally the upper third molar will erupt into a good position. In the lower arch removal of a second permanent molar will yield, on average, around 1–2 mm of space in the premolar region and will provide additional space for eruption of third permanent molar. However, space alone will not ensure that the (unpredictable) lower third permanent molar will erupt into a satisfactory position. The likelihood that the lower third permanent molar will erupt into occlusion is increased if the following factors (as seen on an orthopantomographic (DPT), or lateral oblique radiograph) are satisfied (Fig. 7.12):
  • the angle between the third permanent molar tooth germ and the long axis of the second molar is between 10° and 30°;

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  • the crypt of the developing third molar overlaps the root of the second molar;
  • the third permanent molar is developed to the bifurcation.
Even if these criteria are satisfied, eruption of the lower third molar into occlusion cannot be guaranteed, and it should be made clear to the patient that a course of fixed appliance treatment to upright or align the third molar may be necessary.
Third permanent molars
Early extraction of these teeth has been advocated in the past to prevent lower labial segment crowding. However, most oral surgeons are now unwilling to remove symptomless wisdom teeth. Research into the role of the third permanent molar in lower labial segment crowding has not demonstrated a clear-cut case of cause and effect. Studies have shown that patients with absent third molars are less likely to exhibit crowding, but are also likely to have smaller teeth than average. This topic is discussed in more detail in Chapter 8.
7.7.2. Expansion
Space can be created by expanding an arch laterally, but this is only an option in malocclusions where a unilateral crossbite exists; otherwise the expansion is likely to be unstable. Expansion of a narrow upper arch to correct a unilateral crossbite with displacement is straightforward. If the upper arch is crowded, it is prudent to complete the expansion first before assessing whether extractions are also indicated. Expansion of the lower arch may be indicated if a lingual crossbite of the lower premolars and/or molars exists, but management of this type of malocclusion is the province of the specialist. Crossbites are discussed in more detail in Chapter 13.
7.7.3. Distal movement of molars
Distal movement of the first permanent molar in the lower arch is attempted very rarely, but can be considered if extraction of the lower second permanent molar is planned owing to displacement or space considerations. This can be achieved with a removable screw appliance, or a lip bumper; however, fixed appliances are more commonly used.
Distal movement of the molars in the upper arch may be indicated in the following situations:

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  • Class I with mild upper arch crowding, or mild Class II division 1 with a well-aligned lower arch and molar relationship less than half a unit Class II (Fig. 7.13).
  • Where extraction of both upper first premolars does not give sufficient space to complete alignment and/or overjet reduction in the upper arch (Fig. 7.14).
  • Where early unilateral loss of a deciduous molar has resulted in mesial drift of the first permanent molar.
  • Where the upper arch is crowded but a median diastema is present (Fig. 7.13). Extraction of premolars in this situation may result in a worsening of the diastema.
  • Where the prognosis for stability of overjet reduction is doubtful, it may be wiser to create space for retraction of the upper labial segment by DMUBS rather than extractions.
Fig. 7.13. Because of the presence of an upper midline diastema it was decided to gain space to align the upper arch by distal movement of the upper buccal segments: (a), (b) pretreatment; (c) upper fixed appliance in situ. In these cases it is wise to take the molar further distally than required; (d) post-treatment.
Distal movement of the upper buccal segment teeth usually involves headgear as the motive force. A screw appliance can be used for unilateral movement, but, except in Class III cases, care is required to ensure that anchorage is not lost and it is wise to include extra-oral anchorage in the appliance design.
7.7.4. Enamel stripping
Removal of a small amount of enamel from the mesial and distal surfaces of the lower incisor teeth is known as enamel stripping or reproximation. It is really a ‘last ditch’ method and should only be considered in adults where the lower labial segment is mildly crowded. No more than 1–2 mm of space in total should be gained in this way, and the teeth should be treated topically with fluoride following reduction of the enamel.
7.8. STABILITY VERSUS PROFILE
Wide smiles, with a tendency towards bimaxillary proclination, are fashionable in the USA, where there is a trend for alignment to be achieved by expansion and/or proclination. The drawback to this approach is that movement of the teeth outside their zone of labiolingual balance increases the likelihood of relapse.
It has been suggested by some orthodontists that extractions have a deleterious effect upon the profile. This view is more prevalent in the USA, and as a result, an enormous amount of research to investigate these claims has been carried out. This work suggests that the effect of extractions upon the profile is minimal. For example, in one study (see section on further reading) it was found that the lips of patients who had undergone premolar extractions followed by fixed appliance treatment were retracted only 1–2 mm further on average than those of patients managed by removal of second molars and fixed appliances. Individual variation in soft tissue thickness and growth pattern was noted to be of greater significance.
7.9. PRESENTATION OF THE TREATMENT PLAN TO THE PATIENT
The last step of treatment planning is to present the proposed treatment to the patient and, if appropriate, their parent or guardian. Often there is more than one possible option and each should be presented to the patient with an explanation of the relative merits. It is helpful if this explanation can be accompanied by colour pictures of the appliances to be used.
The nature of the patient’s role in orthodontic treatment should be explained carefully at this stage, particularly the increased likelihood of decalcification and

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periodontal damage if toothbrushing and dietary advice is not followed. If the treatment involves headgear or elastic traction, this should also be discussed. It is wise to overestimate treatment times, even taking into account appliance breakages, holidays, etc. If treatment is completed more quickly the patient will be impressed with your skill. However, in the unlikely event that unforeseen circumstances prolong treatment there will be time to recover.
Fig. 7.14. Patient NM aged 13 years. Class II skeletal pattern (ANB=7°). Upper and lower arch crowding. Buccal segment relationship a full unit Class II left and right. Therefore, this was a maximum anchorage case: (a)–(d) pretreatment. Because the extraction of one premolar in each quadrant would not give enough space to relieve the crowding and reduce the overjet, distal movement of the buccal segments with headgear was indicated. A nudger appliance (see section 16.4.6) was used to aid distal movement (e). Once the upper molars had been moved into a Class I relationship with the lower arch fixed appliances were used to complete alignment and reduction of the overbite and overjet (f); (g)–(i) post-treatment. (NB: The patient still had a Class II skeletal pattern at the end of treatment — dental camouflage was used to compensate for this.)
As in all branches of medicine and dentistry, orthodontic treatment has potential risks. These should be explained to the patient so that their informed consent to the treatment is obtained. However, it is important not to be alarmist and any risks should be put in context. This topic is discussed in greater detail in Chapter 1.
It may be helpful if some written material is provided to back up the information that is given at the consultation, and the patient is allowed some time to reflect upon the proposed treatment at home before reaching a decision on whether or not to go ahead.
PRINCIPAL SOURCES AND FURTHER READING
Bishara, S. E. and Burkey, P. S. (1986). Second molar extractions: a review. American Journal of Orthodontics, 89, 415–24.
An informative review.
British Orthodontic Society (1996). Young practitioner’s guide to Orthodontics. BOS Office, 291 Grays Inn Road, London.
This is a well-illustrated simple introduction to orthodontics.
Dacre, J. T. (1985). The long-term effects of one lower incisor extraction. European Journal of Orthodontics, 7, 136–44.
Dacre J. T. (1987). The criteria for lower second molar extraction. British Journal of Orthodontics, 14, 1–9.
Drysdale, C. et al. (1996). Orthodontic management of root-filled teeth. British Journal of Orthodontics, 23, 255–60.
Lee, R. T. (1999). Arch width and form: A review. American Journal of Orthodontics and Dentofacial Orthopedics, 115, 305–13.
Morse, P. H. and Webb, W. G. (1973). The indication for distal movement of upper buccal segments. British Journal of Orthodontics, 1, 18–26.
NHS Centre for Reviews and Dissemination, York (1998). Prophylactic removal of impacted third molars: is it justified? British Journal of Orthodontics, 26, 149–51.
Recommended reading for all dentists and orthodontists.
Richardson, M. E. and Richardson, A. (1993). Lower third molar development subsequent to second molar extraction. American Journal of Orthodontics and Dentofacial Orthopedics, 104, 566–74.
This article suggests that the criteria for second molar extraction do not need to be as strict as previously thought. However, the author advises the inexperienced orthodontist to limit extraction of lower second molars to those cases satisfying the criteria outlined in Section 7.7.1.
Staggers J. A. (1990) A comparison of second molar and first premolar extraction treatment. American Journal of Orthodontics and Dentofacial Orthopedics, 98, 430–6.
The author reports that the facial profile resulting after extraction of second molars was not statistically different from that resulting after extraction of first premolars, despite further retraction of the incisors in the latter group. Well worth reading.
Swessi, D. M. and Stephens, C. D. (1993). The spontaneous effect of lower first premolar extraction on the mesio-distal angulation of adjacent teeth and the relationship of this to extraction space closure in the long-term. European Journal of Orthodontics, 15, 503–11.
The title is fairly self-explanatory regarding the aims of this study. The authors found that excessive tipping of the canine and second premolar was the exception rather than the rule when lower first premolars were extracted and no appliances used.
Tulloch, J. F. C. (1978). Treatment following loss of second premolars. British Journal of Orthodontics, 5, 29–34.

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Young, T. M. and Smith, R. J. (1993) Effects of orthodontics on the facial profile: a comparison of changes during non-extraction and premolar extraction treatment. American Journal of Orthodontics and Dentofacial Orthopedics, 103, 452–8.
‘…the results provide additional evidence that it is simplistic and incorrect to blame undesirable facial aesthetics after orthodontic treatment on the extraction of premolars’.
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