Orthodontic assessment

16 May

Orthodontic assessment
A brief examination of the developing occlusion should be carried out around 7 to 8 years of age to check upon the presence and position of the permanent incisor teeth and to help detect at an early stage any incipient problems which may hinder the normal eruption sequence (see Chapter 3). Radiographic examination is indicated at this stage if an abnormality is suspected. In general dental practice, a child’s dental and occlusal development should be checked yearly, and from around 10 years of age the routine dental examination should be extended to include palpation for unerupted maxillary permanent canines in the buccal sulcus.
Prior to the commencement of orthodontic treatment a full examination (including radiographs) and assessment of the occlusion needs to be carried out, which for most children is not before the eruption of the permanent dentition. However, for those with a skeletal discrepancy where treatment may need to be timed to coincide with the pubertal growth spurt, it may be prudent to carry out a full assessment earlier.
The purpose of an orthodontic assessment is to evaluate and record the features of a malocclusion in preparation for planning treatment, if indicated. The following approach is suggested because it has been successfully used by the author and others, but the exact sequence of the examination is unimportant. However, a consistent logical approach is essential to avoid omissions.
5.2.1. Instruments
A mirror, probe, and stainless steel orthodontic (or engineer’s) rule are required.
5.2.2. Study models
The assistance provided by a set of study models during assessment and treatment planning cannot be over-emphasized. In addition, they are essential as a pretreatment record if any appliance therapy is to be carried out. To be of value the study models should include all erupted teeth, the palate, and the full sulcus depth. They should at least be trimmed so that the upper and lower bases are parallel with the occlusal plane; however, traditionally orthodontic study models are trimmed so that the heels and sides are flush (Fig. 5.1), allowing the models to be placed down in any position and remain in occlusion.
Fig. 5.1. Trimmed orthodontic models.
Orthodontic assessment
5.2.3. Radiographs
See Section 5.8.
It is extremely important to determine the patient’s opinion regarding the position and alignment of their teeth. It is not uncommon for an orthodontic opinion to be sought at the instigation of a anxious parent when the child concerned is quite happy with their occlusion and certainly not prepared to entertain the idea of wearing appliances. No matter how enthusiastic a patient’s parents may be for their offspring to undergo orthodontic treatment, if the child itself is not willing, then a successful outcome is less likely. Adult patients are usually keen and cooperative once they have decided to go ahead with appliance treatment.
It is also important to ascertain exactly which features of the occlusion concern the patient. A child may be more concerned about the mild rotation of an upper central incisor than increased overjet, particularly if other members of the family have Class II division 1 malocclusions. Naturally they will not be content if, at the completion of treatment for their increased overjet the rotation is still present.
It is often helpful to determine the types of appliance that the patient is willing to accept — examples of the different appliances or good colour pictures are invaluable at this stage.
Regular dental care and good oral health are an essential prerequisite to orthodontic treatment. The patient’s past dental history should include details of any previous appliance therapy. If permanent teeth have been extracted, the timing of these extractions and the reason for removal should be ascertained if possible.
A thorough medical history should be taken. Conditions which might affect orthodontic treatment include the following:
  • Rheumatic fever. If a patient is suspected of being at risk of infective endocarditis it is advisable to seek medical advice, preferably from a cardiologist. If the risk is confirmed then orthodontic treatment can be considered provided the patient is able to maintain good gingival health and accepts the risk involved. Invasive procedures, for example, extractions and band placement and removal (however, some authorities suggest bonds should be used in preference for bands in susceptible patients), should be covered with the recommended antibiotic cover regime. A chlorhexidine rinse prior to adjustment of a fixed appliance is a useful adjunct, although daily long-term use of chlorhexidine may lead to bacterial resistance. If the patient’s oral hygiene deteriorates during treatment it may be advisable to discontinue appliance treatment.
  • Epilepsy. Because of the risk of damage to the mouth caused by a broken appliance during an epileptic attack, it is prudent to delay treatment in this group of patients until the condition is well controlled.
  • Recurrent apthous ulceration (RAU). This condition of (much) debated aetiology is known to be exacerbated by trauma to the mucosa. Cribs or springs on


    a removable appliance, or the components of a fixed appliance, may be sufficient to set off an attack in a susceptible individual. In patients with a history of RAU, it may be prudent to carry out a thorough investigation first, including referral for blood tests if indicated, and to determine the effect of appliances before any irreversible steps, for example extractions, are taken.

  • Hay fever. Atopic children may experience problems with a functional appliance during the summer months.
Of course, there are many more esoteric conditions that will modify treatment in affected individuals. However, there is only space here to comment that when in doubt a specialist opinion should be sought.
The position of the teeth is determined largely by a patient’s underlying skeletal pattern and the soft tissue environment. The purpose of this aspect of the examination is to evaluate their relative influence in the aetiology of a particular malocclusion and also the degree to which they can be modified or corrected by treatment.
5.6.1. Skeletal pattern
The patient should be comfortably seated upright. Tilting of the head upwards increases the prominence of the chin, and conversely tilting the head downwards has the opposite effect. Therefore it is important to ensure that the patient is positioned so that his or her Frankfort plane (uppermost aspect of the external auditory canal to the lowermost aspect of the orbital margin) is horizontal. The teeth should be together in maximum interdigitation — it is wise to check this, as often a patient will posture the mandible forwards with only the incisors in contact.
The skeletal pattern should be asesssed in all three planes of space.
The patient should be viewed from the side and the relative position of the maxilla and mandible assessed (Fig. 5.2). It is important to look at the region of the dental base rather than the lips, as their position will be influenced by proclination or retroclination of the incisors. The following classification of skeletal pattern is universally recognized:
  • Class I — the mandible is 2–3 mm posterior to maxilla.
  • Class II — the mandible is retruded relative to the maxilla.
  • Class III — the mandible is protruded relative to the maxilla.
It is important to note that this classification only gives the position of the mandible and the maxilla relative to each other and does not indicate where the discrepancy lies. A lateral cephalometric radiograph is required for further assessment of the aetiology of the skeletal pattern. If a skeletal discrepancy is present, an assessment of its severity should be made.
Again, the patient is viewed from the side. The vertical assessment comprises two separate evaluations:
Fig. 5.2. Assessment of anteroposterior skeletal pattern: (a) Class I; (b) Class II; (c) Class III.
anteroposterior skeletal pattern
  • Lower facial height (Fig. 5.3): the distance from the eyebrow to the base of the nose should equal the distance from the base of the nose to the lowermost point on the chin. If the latter distance is increased, the lower facial height is described as being increased, and vice versa.
  • Frankfort mandibular planes angle (FMPA) (Fig. 5.4): assessment of the FMPA clinically by eye comes with experience, but the neophyte orthodontist may find it helpful to assess this angle by placing one hand level with the Frankfort plane (external auditory meatus to the lower border of the orbital margin) and the other hand level with the lower border of the mandible. Then in the ‘mind’s eye’ extrapolate the planes and assess where they would cross. If the angle between these two planes is around the average of 28°, then the lines would intersect approximately at the back of the head. If the FMPA is increased the lines would meet before the back of the head, and if it is reduced they would cross beyond.
It is important to remember that all faces are asymmetric to a small degree. However, any marked discrepancies should be noted. For this assessment the patient should be viewed anteriorly and, if an asymmetry is noted, also examined by looking down on the face from above. The extent of the asymmetry and whether only the lower facial third or the maxilla or orbits are involved should be recorded. Whether the occlusal plane follows the asymmetry and ‘runs’ down to one side should be established by asking the patient to bite onto a tongue spatula (Fig. 5.5).
Fig. 5.5. Use of a tongue spatula to highlight a ‘run’ in the occlusal plane in addition to a small degree of facial asymmetry.
5.6.2. Soft tissues
Assessment of the soft tissues should commence as soon as the patient enters the surgery and continue during the preliminary stages of the assessment in order to be able to observe normal function.
Orthodontic assessment
Orthodontic assessment
The following should be considered:
  • The form, tonicity, and fullness of the lips (Fig. 5.6). For example, are they full or thin, hyperactive, or with little tone?
  • Lip competence. Competent lips meet together at rest without any muscular activity (Fig. 5.7). If a patient’s lips are incompetent, the method by which they achieve an anterior oral seal should be evaluated. This is usually either by tongue to lower lip contact, with the lower lip being drawn up behind the upper incisors, or by the patient bringing the lips together. An assessment should also be made as to whether the lips are potentially competent (Fig. 5.8). This is most relevant in Class II division 1 malocclusions where it is important to assess whether the lower lip will act in front of the upper incisors to retain their corrected position following overjet reduction (see Chapter 9).

  • Lower lip position relative to the upper incisors. A high lower lip line (Fig. 5.9) is often one of the aetiological factors in Class II division 2 malocclusions.
  • The length of the upper lip and amount of upper incisor shown. The normal upper incisor show, at rest, is 2–3 mm in females and less in males (Fig. 5.10)
Orthodontic assessment
Fig. 5.7. (a) Competent lips which meet together at rest; (b) incompetent lips as they require muscular effort to achieve contact.
Orthodontic assessment
Orthodontic assessment
Fig. 5.9. High lower lip line relative to the upper central incisors which has resulted in their retroclination. The shorter lateral incisors have not been affected by the lip.
Tongue thrusts are usually adaptive, i.e. the tongue is placed forward between the teeth to help achieve an anterior oral seal during swallowing. Rarely, patients are encountered who appear to have a habit of pushing their tongue between the upper and lower incisors when swallowing; this is described as an endogenous or primary tongue thrust. The significant difference between the two is that an adaptive tongue thrust will cease following treatment when a lip-to-lip contact can be achieved, whereas an endogenous tongue thrust will not and this often leads to relapse (this is discussed in greater detail in Chapter 12, Section 12.2.2).
5.6.3. Temporomandibular joints
Before any examination of the temporomandibular joints is carried out the patient should be asked about symptoms. The joints should be palpated simultaneously by placing the middle finger over the condylar head whilst the patient is instructed to open and close and to move laterally. Any clicks, crepitus, and locking should be recorded. It is probably prudent to record any negative findings as well. If definitive symptoms exist, the muscles of mastication should also be examined for areas of tenderness.
Fig. 5.10. Excessive amount of upper incisor show (a) at rest and (b) when smiling.
Orthodontic assessment
5.6.4. Habits
Enquire about any habits, whilst observing the patient’s hands for any signs of digit sucking or nail-biting (the latter has been associated with a increased incidence of root resorption).
With a little experience it can be easy to spot the occlusal features of a fingeror thumb-sucking habit (Fig. 5.11). Some patients develop a lip-sucking habit, which can lead to a eczematous appearance of the skin below the lower lip in addition to retroclination of the lower labial segment.
The effects of any habit upon the dentition should be brought to the attention of the child and their parents.
5.7.1. Dental examination
This should include the following:
  • Charting all the erupted teeth.
  • Noting any permanent teeth of poor prognosis, untreated caries, and the patient’s caries rate.
  • Oral hygiene and gingival condition. Any gingival recession, and any areas with a reduced width of attached gingiva, should also be noted.
  • Any teeth with an abnormal morphology or size.
  • Anterior teeth which have suffered trauma.
5.7.2. Path of closure
The patient’s position of maximum interdigitation (intercuspal or centric position) should be examined together with their path of closure from the rest position. This can often be difficult at an initial consultation when the patient is a little apprehensive, and is occasionally impossible in the younger child. Therefore care is required to ensure that the patient’s true intercuspal position is recorded, particularly in Class II division 1 malocclusions where the patient may tend to posture forwards. Asking the subject to curl the tongue up to touch the back of the palate, whilst closing the teeth together, can be helpful.
Displacement on closure
A premature contact encountered on closure from the rest position is uncomfortable and the patient soon learns to displace the mandible forwards or laterally to avoid the offending tooth or teeth (Fig. 5.12). This displaced position quickly becomes learned and so can be difficult to detect. It is advisable to assume that any unilateral crossbite is associated with a displacement until proved otherwise, and to examine carefully the path of closure and centrelines. Where a displacement exists, the occlusion should be assessed in maximum interdigitation and the direction and amount of displacement recorded.
Orthodontic assessment
Fig. 5.12. Diagram to illustrate the displacement of the mandible laterally into a unilateral cross bite: (a) initial contact on hinge axis closure; (b) displacement into maximum interdigitation (note shift of lower centre line relative to upper arch).
Deviation on closure
This is most commonly seen in association with Class II division 1 malocclusions where the patient has a tendency to hold the mandible forward to mask the underlying problem. This used to be rather aptly described as a ‘Sunday bite’. On


closure from the rest into the intercuspal position, the mandible can be seen to translate backwards and upwards.

5.7.3. Labial segments
Labial segment alignment
First the lower and then the upper labial segment should be examined in turn and the following recorded:
  • Angulation relative to mandibular/maxillary base.
  • General alignment and the presence of crowding and spacing.
  • Any rotated teeth and those displaced from the line of the arch.
  • The inclination of the canines if they are erupted or, if not, whether they can be palpated buccally in a favourable position.
Labial segment relationship
The patient should be guided into maximum interdigitation and the following recorded:
  • Incisor relationship (see Chapter 2, Section 2.3.2).
  • Overjet — from the mesial aspect of the upper central incisors to the lower incisors in millimetres (Fig. 5.13).
  • Overbite — in terms of overlap of the lower incisors by the upper incisors (Fig. 5.13). Normal overbite is a half to a third of the lower incisor crown height. However, it is usually sufficient to record overbite as increased, reduced, or normal. Whether the overbite is incomplete or complete onto tooth or the palate should also be noted, and if an anterior open bite is present, its extent should be recorded in millimetres. A traumatic overbite is said to be present if obvious ulceration is evident where the lower incisors make contact with the palatal tissues (Fig. 5.14).
  • Presence of any anterior crossbites.
  • Check whether the centrelines of each arch are coincident with the centre of the face and with each other. Measure and record any discrepancies in millimetres.
Orthodontic assessment
Orthodontic assessment
Fig. 5.15. Note how the upper buccal segment teeth are tilted palatally in this photograph.
5.7.4. Buccal segments
Buccal segment alignment
Again, first the lower and then the upper buccal segments should be examined in turn and the following recorded:
  • General alignment and the presence of crowding or spacing.
  • Any rotated teeth and those displaced from the line of the arch.
  • Angulation relative to their respective bases (Fig. 5.15). This is of most relevance where a posterior crossbite exists.
Buccal segment relationship
The patient should be guided into maximum interdigitation and the following recorded:
  • Molar relationship (if a corresponding molar is present in each arch).
  • Canine relationship (Fig. 5.16).
  • Presence of any crossbites.
Orthodontic assessment
Before radiographs can be prescribed a thorough examination of the patient should be carried out so that the views indicated on clinical grounds can be taken at the same visit. The commonly used views include the following:
  • A panoramic view — an orthopantomographic (DPT) radiograph, or left and right lateral obliques.
  • A lateral cephalometric radiograph — indicated for skeletal discrepancies and/or where anteroposterior movement of the incisors is required (see Chapter 6).
  • A view of the upper incisors — either a periapical or an upper anterior occlusal. There has been some controversy as to the efficacy of this aspect of the radiographic examination in the light of radiographic dosage. It has been argued that only rarely does this view reveal a unexpected abnormal finding that is not indicated on the panoramic view (Fig. 5.17). Obviously where there is reason to suspect pathology (for example failure of eruption or a history of trauma) an intra-oral radiograph of this area is indicated. Also a panoramic view may need to be supplemented with an intra-oral view to check the upper incisors radiographically prior to starting treatment to check for evidence of root resorption, root fracture, or supernumerary teeth.
Fig. 5.17. (a) DPT and (b) peri-apical radiographs of the same patient. The intra-oral radiograph revealed a supernumerary tooth which was not evident on the OPG radiograph.
The radiographs taken should be examined as follows:
  • Check the clinical charting and to record the presence of any unerupted teeth.
    Any missing teeth (congenitally absent or previously extracted) should be noted.
  • Assess the position and degree of development of any unerupted teeth which should also be studied for any abnormalities.
  • Note any teeth with large restorations or untreated caries.
  • Look for evidence of root resorption and apical pathology.
  • Cephalometric tracing described in Chapter 6.
Fig. 5.18. These photographs are of a patient called Claire. The following summary of her malocclusion was compiled after a thorough assessment which included radiographs (not shown):Claire is aged 12 years and has a Class I incisor relationship on a mild Class III skeletal pattern with slightly increased vertical proportions. She has a mildly crowded lower arch and a moderately crowded upper arch with rotated upper lateral incisors and a buccally displaced 3/.
Following a thorough orthodontic examination a summary of the salient features of the malocclusion should be recorded. This usually involves the following:
  • The patient’s name and age.
  • A description of the incisor relationship, by classifying as Class I, Class II division 1, Class II division 2, or Class III (see Section 2.3.2) where possible. However, if there is any doubt it is often better to describe the overjet and overbite in words.
  • Skeletal pattern.
  • The presence of crowding or spacing.
  • Any other features of note, for example absent teeth, displaced teeth, cross-bites, or displacement on closure.
An example is given in Fig. 5.18. This approach helps to highlight the important features of a malocclusion and provides a problem list, thus facilitating treatment planning (Chapter 7).
British Orthodontic Society Development and Standards Committee. (1999). Orthodontic records: collection and management.
Isaacson, K. G. and Jones, M. L. (ed.) (1994). Orthodontic radiography: guidelines. British Orthodontic Society, 291 Grays Inn Road London.
This pamphlet gives the recommendations of the British Orthodontic Standards
Working Party on which radiographs to take and their timing to achieve maximum diagnostic information with minimum X-ray dosage.
Khurana, M. and Martin, M. V. (1999). Orthodontics and Infective endocarditis. British Journal of Orthodontics, 26, 295–8.
McDonald, F. and Ireland, A. J. (1998). Diagnosis of the orthodontic patient. Oxford University Press, Oxford.
Stephens, C. D., and Isaacson, K. (1990). Practical orthodontic assessment. Heinemann Medical Books, Oxford.
This excellent book contains a very good résumé of diagnosis and treatment planning, but consists mainly of clinical cases for the reader to practise upon and learn from.
Taylor, N. G. and Jones, A. G. (1995). Are anterior occlusal radiographs indicated to supplement panoramic radiography during an orthodontic assessment? British Dental Journal, 179, 377–81.
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