Examination of Gathered Material
The information that can be obtained from facial photographs (i.e., analysis of the face), from color photographs, or transparencies of the mouth, and from radiographs, is dealt with here. After the apical area analysis, the model examination is discussed, including three analyses. Finally, comments are made about evaluation of function.
In the course of the examination of the various diagnostic aids, information obtained from other sources is also included.
Despite the fact that photographs accurately reproduce a face, they can only do so at one moment and from one viewpoint. For instance, profile films give an indication of facial configuration as seen only from the side, revealing the anteroposterior position of the nose, lips and chin. In addition, double proposition, or a dished-in face, show up clearly on such photos, with the form and vertical proportions of the face well portrayed. Profile photographs give two-dimensional information, are easy to take under standardized conditions (like lateral skull radiographs) and are readily analysed. Moreover, standardized photos make it possible to record changes in the face due to growth and orthodontic treatment. This applies much less to photographs taken “en face” because such changes, while visible sagittally and slightly less vertically, are barely detectable transversely.
The combination of both profile and frontal photographs will give a better overall but static impression whereas “laughing” photographs will give an indication of activity, especially if taken from an angle in front. These photographs exhibit some of the liveliness, expression and facial animation of the patient, though, above all, they reveal the dentition in a better way. Profile photographs are not well suited for this purpose, despite their traditional use in assessing a face.
One can really only come to appreciate the different features that make a face more or less attractive when viewing the head to which the face belongs. Therefore, in assessing a face from photographs, one should recognize the importance of any notes available from direct observation of the patient. Data from dental casts and radiographs should also be incorporated.
In the pictorial arts and in standards of beauty over the centuries, a straight profile has been preferred to a convex or concave one (Fig. 5-1). The anteroposterior position of the straight profile was, and still is, judged differently. For example, in classical sculpture, the Greek gods were often portrayed with the lower third of the face returned. In the middle of the 20th century, preference was given to mannequins and models with a proportionately far, ventrally placed lower facial third.338
Today, a concave profile with a fallen-in mouth (“dished-in” face) is considered ugly. The opinions respecting the extent to which the dentition may be prominent (double proposition) vary enormously. This also applies to how much of the teeth should show when talking and laughing and it is generally felt that the exhibition of a wide area of gum is not particularly desirable.
A normal occlusion may be found in different facial configurations, so it is useful to differentiate those configurations in the same way that Schwarz did in his cephalometric analysis of the skull. Schwarz started with the average, straight profile and, in comparison, the lower facial component can be displaced ventrally or dorsally, or be titled forwards or backwards. Combinations of parallel displacement with tilting can also exist. In this way, nine different facial types (all possessing normal occlusion) can be distinguished (Figs. 5-2 and 5-3). Schwarz held that a profile with the lower third rotated backwards, with a retruded chin, was less desirable than a straight profile. The anteroposterior location of the lower facial component is, this respect, of little importance.338
It is maintained that the different orthodontic anomalies can, in principle, be superimposed on all the facial types distinguished by Schwarz, though there are certainly preferred types for particular abnormalities. In this way, orthodontic anomalies with a sagittal or vertical deviation are often associated with particular facial configurations. For instance, Class III cases have lower lip and chin dominant, while Class II/1 cases usually show the reverse. With a pronounced anterior open bite, there is often a longer lower facial third with a retruded chin In orthodontics, lateral skull radiographs have played a dominant role in assessing the face. The accent was placed on the anteroposterior relationships of a number of measuring points. However, sometimes there was an overemphasis and unjustified faith in the significance of the position and inclination of the mandibular incisors.379 Moreover, it turned out that one of the important measuring points (Downs’ A point*) was unreliable and frequently not representative of the intended purpose.386 Further, it has been found that the shape and thickness of the soft tissue drape can vary so much that study of the underlying skeletal structure cannot be used directly to assess facial harmony.67 Indeed, even for experts, it is not possible to make a reasonable guess as to the hidden morphology of the craniofacial skeleton on the basis of profile photographs.116 117 A lateral skull radiograph can show a striking double proposition of the incisors, yet because of the way the soft tissues cover the skull, they are neither recognizable nor ugly.70 The above aspects of appearance are largely related to the great variation in position, thickness and form of the covering soft tissues, particularly of the lips. An analysis that considers only the dentition and the craniofacial skeleton is thus quite limited, and bearing in mind the cost and radiation dose involved in using lateral skull radiographs, it should be clear that one should at least initially try to perform an analysis of the face without a radiograph.
The anteroposterior position of both jaws, with respect to the bony structure of the head, and their mutual relationship, can be judged on the patient himself. The most dorsally located parts of the anterior aspect of the alveolar process of each jaw (comparable with Downs’ points A and B*) can readily be established by palpation;97 257 their sagittal location giving a good indication of the anteroposterior relationships of the tooth-bearing bones. If one now takes the plaster models and mentally projects these points onto the occlusal plane (corresponding with the “Wits” analysis†), then one obtains a better idea of the size of a possible deviation, and of the distance that has to be bridged by treatment.159
The inclination of the maxillary central incisor can be assessed from the face itself. The labial surface of the crowns should run approximately parallel with the line imagined from the forehead to the chin point. The level of the lip line (stomion) relative to these teeth can best be determined clinically.
Fig. 5-1 Different facial forms distinguished in profile sketches by Albrecht Dürer.
On the left is the straight profile; in the middle is the circular, curved, convex profile; on the right is the hollowed out concave profile. (Dürer, A.: De symmetria partium humanorum corporum. Nürnberg, 1532)
Fig. 5-2 Nine facial types as distinguished by Schwarz, based on the position and rotation of the lower part of the face, bordered by the plane of the nasal floor.
(Modified illustration from: Brückl, H.: Zur schematischen Darstellung und Klassifizierung der Einlagerungsmöglichkeiten des Gebisses im Schädel nach dem Verfahren von A.M. Schwarz. Fortschr. Kieferorthop. 17: 283–290, 1956).
Fig. 5-3 An illustration of the skeletal basis of the facial types distinguished by Schwarz. In the average face the plane of the nasal floor is at 85° to the perpendicular (Pn) from the Frankfort Horizontal Plane (H). In a “dorsally rotated dentition” () the angle is less than 85°; in a “ventrally rotated dentition” () larger than 85°. Rotation of the lower part of the face can be combined with a bodily displacement ventrally (anteface ) or dorsally ( retroface).
(From: see Fig. 5-2)
The distinction made by Schwarz between the position and the rotation of the lower part of the face in relation to the rest of the head can be reasonably well seen after a little practice, particularly if the dental casts are held next to the face and oriented to correspond with the real dentition.
With an open bite, one would be more alert to aspects of vertical dimensions. The models and facial photos indicate the height of the lower face. Palpation reveals certain details of the mandible (e.g., slope of the lower border of the mandible, antegonial notching and differences in anterior and posterior facial height.)
A special aspect of the analysis of the face is the prediction of changes that are associated with growth and therapy. As a rule, without intervention, there is little change seen in facial configuration.60 239 A long lower face with interposition of the tongue retains its characteristics, as does a shallow lower face height with a surplus of facial musculature.
With facial orthopedic (and surgical) treatment, radical facial changes can be achieved. This applies to both Class II/1 and Class III anomalies. Retraction of the incisors, especially following extraction of premolars, can also give a significant alteration in facial form and expression. When dealing with growing individuals, it is essential to superimpose the facial changes expected from the treatment onto those changes that would occur due to growth.
The most notable changes in the face as a result of orthodontic and facial-orthopedic treatment are those in the region of the nose, chin and especially the lips.359 Sagittal movement of the maxillary incisors, and to a lesser degree of the mandibular incisors, strongly influences the position of the upper lip, but less so of the lower lip.254 305 The retraction of the maxillary incisors does not lead to the same degree of retraction of the lips, but rather to barely a half, or a quarter, of the distance that the teeth went back.404
In respect to faces, decision making is made more difficult by the lack of objective criteria. The faces advocated in orthodontics are based on personal preferences, and social and cultural values which are exercised by a selected group. Criteria derived in that fashion are sometimes rather divorced from the real requirements of the patient.173
In Figures 5-5 and 5-6, the facial analysis that can well be performed on photographs is further detailed, resulting in an overall impression of the sagittal and vertical proportions. The illustrated norms are averages. It is not practicable to indicate when normal values are exceeded. However, by the use of reference lines, a conclusion can be reached, regarding prognathism or retrognathism, on whether a lower face height is too large or too small, or if the upper lip is too long or too short, etc. In working with this analysis, one has to realize that an incorrect determination of the Frankfort Horizontal Plane will influence the judgement of sagittal features.
Fig. 5-4 Schwartz’s profile analysis.
A A line (Pn) is drawn through skin nasion (n) perpendicular to the Frankfort Horizontal Plane; a similar line (Po) is drawn through orbitale (Or). The underside of the chin is projected onto Pn at gn. Between Po and Pn is the “Kieferprofilfeld” (KPF) (“Jaw-profile field”).
B The vertical distance between subnasale (sn) and stomion (sto) is half of the distance between the projections of stomion (sto) and gnathion (gn) on Pn. The tangent (T) from subnasale (sn) to pogonion (pog) passes through the upper lip (ls) in the middle of the pink area and touches the lower lip (li).
(Schwarz, A. M.: Wie der angehende Kieferorthopäde Gesicht und Schädel verstehen lernt. Urban & Schwarzenberg, Wien, 1955).
Fig. 5-5 Schwarz’s profile analysis applied to a lateral profile photograph.338 The reference lines (already described in Fig. 5-4) serve to facilitate assessing the profile. There are no values to indicate if a face is outside the norms. Whether one finds for example that an upper lip lies too far ventrally or the chin is too far retruded is a subjective matter.
Fig. 5-6 Schwarz’s analysis applied to a frontal facial photograph.338 A significant variation in facial proportions exists that still would be considered normal. The proportions given are only intended to facilitate assessment. It is not possible to draw positive conclusions from these, unless the deviation is already excessive. The reference lines serve usefully to indicate asymmetries.
It is emphasized again that an analysis of the face should be based on sound observation (including palpation) of the patient both relaxed and laughing, and when speaking. Important points to note are the thickness of the lips and cheeks, the padding of the nasolabial fold and plica mentalis. Models and photographs can provide further, important information. In particular, facial photographs are excellent in recording a particular situation and in assessing faces by drawing reference lines on the photograph itself.
Finally, there are cases when it is not possible to arrive at a responsible diagnosis and treatment plan without the use of cephalometric radiographs. However, as already mentioned, instruction in the interpretation and use of these radiographs is beyond the scope of this book.
From color photographs or slides, it is possible to abstract information on a number of essential matters. For example, one can record the conditions of oral hygiene, color of teeth, possible decalcifications, state of gingivae, etc, as well as details of the occlusion. Although the sagittal and transverse occlusion may not always be easy to assess on these photographs, the vertical occlusion is usually clear to see which is of particular importance in detecting open bites, especially in the posterior segments. In addition, by means of serial photographs, it is easy to observe and verify changes occurring during development or orthodontic treatment.
Numerous matters of importance in orthodontic diagnosis can be established by a radiograph. In discussing these issues (and it is not pretended that the list is complete) the divisions of the patient record card are followed (see here).
In diagnosis a panoramic radiograph of the lower face usually suffices. Sometimes it may be needed to supplement this with periapical films of particular areas. As remarked previously, extra exposures should only be made in cases where there is a positive indication. For example, most panoramic radiographs lose detail in the incisor regions so it may be necessary to take a periapical or occlusal film of that region, especially if fuller information is needed and other means cannot provide sufficient evidence to check on, say, trauma, a pulp that does not react to testing, or an indistinct anomaly on the panoramic film. Further, if the presence of a possible interproximal cavity on the panoramic film cannot be confirmed or denied by clinical examination, then it is wise to take bite wings.
Absent teeth are most easily checked by systematically inspecting the film from the midline outwards, identifying and counting each tooth in both jaws, including the third molars. This applies particularly to the permanent teeth. Lack of deciduous teeth is also of importance in very young children. In the assessment, one needs to remember that in young children the tooth germs of some permanent teeth, such as the second premolars, are often not developed far enough to be visible on a radiograph.
Supernumerary teeth are revealed. If the films are checked as suggested above, the film should be especially carefully examined if the incisor region is not clearly shown. Also, If a lateral skull radiograph is available, this should be scrutinized carefully for supernumerary teeth and other anomalies. If, however the situation is still uncertain, a separate film should be taken of the region in question. Occasionally, teeth are so projected over one another that proper interpretation is difficult. Here, a knowledge of dental anatomy (e.g., number of roots, root canals) can help clarify things, but if in doubt, an intra-oral film can resolve the problem.
A tooth may be present unerupted, but deformed, or hypoplastic. If this occurs, such a tooth might be useless on emergence and, if there is little root formation while the apex is already closed or nearly closed, the prognosis is poor. Occasionally, internal or external ideopathic resorption is seen with permanent teeth. Curved or convoluted roots, whether or not the result of trauma, can produce problems during extractions. Root fragments should be recorded.
Some teeth will not, or cannot, emerge into the oral cavity because they are impacted. For example, a mandibular second premolar may be jammed between its neighbours and consequently cannot erupt, and a horizontally located canine has almost no chance of emerging unaided. Different-sized x-ray images of corresponding teeth (e.g., canines) may indicate abnormal positions and sometimes impaction of one or the other. (The difference in size is a geometric consequence of one tooth being at a different distance from the film than is its counterpart.) Since abnormal positions can affect treatment, they should be noted. In young children, it is difficult to know whether or not third molars are forming. As a rule of thumb, it can be said that the formation of the crypt of a developing third molar should be visible when the furcation of the adjacent second molar has formed. Therefore, if third molars are not (as yet) visible, then this should be recorded. It is in fact wise to note any abnormal angulations, since they may cause future problems. It is also useful to observe where the crypts or crowns of the mandibular third molars are in relation of the occlusal plane, and to what extent the crown formation and calcification have progressed. The question of spatial relationships in the molar region, insofar as this can be derived from a panoramic radiograph, is discussed later.
Anomalies in eruption paths can affect other teeth, though not as frequently as this happens with third molars. In general, teeth are projected onto a panoramic film with their root axes approximately perpendicular to the occlusal plane. They therefore exhibit a mutual parallelism, but sometimes it is apparent that a tooth during eruption is diverging from this direction, and/or is rotated around its long axis. This is an important point, as anomalous eruption can lead to root resorption of an adjacent permanent tooth, or to impaction of the tooth in question. In any event, deciduous teeth may resorb in an atypical fashion and the permanent tooth may emerge in the wrong place, or not at all.
The probable emergence sequence of the premolars and permanent canines can be observed on a panoramic radiograph. Insight into this sequence is important in identifying crowding and predicting which tooth may be most affected. When all the teeth have not yet emerged the probable sequence of emergence in each quadrant may be recorded for the canines and premolars. For example, a sequence on the maxillary right side of, first, the P1, then the P2 and then the C may be marked as 4,5,3, on the record card.
Dental age can be estimated by the developmental stages of the individual teeth. (For further information on these stages, see “Development of the Dentition”395). Occasionally a tooth deviates from the average pattern, but this need not alter the overall picture. Rather, it is the general impression that counts.
Root resorptions are found in both deciduous and permanent teeth, and should be differentiated into internal and external resorptions. Internal resorption is often associated with trauma but in the deciduous dentition, root resorption is a normal phenomenon, with the pattern and rate of resorption being important. For example, resorption of only one root of a deciduous molar will have consequences for its successor. In cases with agenesis of a permanent tooth, the extent of resorption of the corresponding deciduous tooth in relation to the patient’s age and the resorption of his other teeth is relevant for future treatment.
In the permanent dentition, root resorption can be limited to one tooth or few teeth, or may be general. Additionally, considerable root resorption can limit the life of a tooth and if very short roots are seen, one should consider the possibility of earlier trauma or apicectomy. Root resorption of several teeth can be the result of earlier orthodontic treatment; general root resorption without a history of earlier tooth movement would usually be a contraindication for orthodontic treatment.
Endodontic treatment, if properly completed, has no effect on orthodontic treatment. In maxillary incisors, endodontic treatment is frequently needed as a consequence of trauma; extra care is needed when looking for signs of ankylosis or resorption. After treatment for apical infection, complete healing may take some time, during which tooth movement may provoke an undesirable reaction. This should be borne in mind, and the date recorded of when any endodontic treatment was carried out. If endodontic treatment has been required in posterior teeth, it is often an indication of neglect or of a high level of susceptibility to caries. In cases where extractions are indicated for the orthodontic treatment, it is advisable to look very seriously at the choice of endodontically involved teeth as the teeth to be removed.
Teeth with periapical lesions should be assessed in the same light as those already endodontically treated. The extent of the abnormality may not be easily seen unless the periapical radiograph is of an excellent quality. In any case, the abnormality would have to be first eliminated by endodontic treatment, surgery, or extraction.
The radiographs may disclose caries not revealed in the clinical examination and, since caries can interfere with the initiation of treatment, this is one of the first things to look for. Any necessary conservative work should precede orthodontic treatment.
Bone resorption is a feature of periodontal disease and should be recorded whenever it is observed on radiographs. It should be remembered, however, that normal radiographs are seldom taken under conditions suitable for sensitively revealing bone loss, and that what is observed will probably be already quite severe. Other radiographic features to be noted include cysts, granulomata, odontomes, fracture lines, etc.
Once again, it must be remembered that though panoramic radiographs are invaluable for general survey, they will not generally reveal caries or bone lesions until they are quite far advanced.
On a panoramic radiograph, the relationship between the size of the jaws and the overall size of the teeth that are to be accommodated in them, can be partly judged. For the criteria that are involved, see the discussion on Apical Area Analysis that follows. It is enough to identify such parts of the jaws which can be found on the panoramic radiograph, and determine if they are abnormal in shape or size.
Panoramic radiographs also portray the ramus and condyle of the mandible for overall assessment, as well as showing part of the structures lying cranially to the floor of the nose. It is therefore possible to see a deviation of the septum of the nose, for example.
The relationship between the developing dentition and the growth of the jaws are looked at not so much as a whole, but divided into compartments. The problems that can present, and the limitations and possibilities that exist for improvement, are easier to understand if each jaw is subdivided in three sections: anterior, middle and posterior (Fig. 5-7).
The concept of the “apical area” was developed by Van der Linden in 1979,392 and described as follows:
“The apical area in the newborn child and during the first year of life consists of the region in which the developing parts of the deciduous and permanent teeth are to be found. In the deciduous dentition, the apical area consists of the region occupied by the apices of the deciduous teeth and the developing parts of the permanent teeth. In the period of the mixed dentition, the apical area is the region in which the apices of deciduous teeth and permanent teeth lie and where the developing parts of the unemerged permanent teeth are to be found. In the adult, the apical area is the region in which normally the apices of the permanent teeth can be located.”
In assessing the size of the separate sections of the apical area in which not all the permanent teeth have emerged, a panoramic radiograph is very useful. This applies especially to the middle section, in which the mutual relations of the unemerged premolars and permanent canines, particularly in the maxilla, are important criteria. Judgement of them in the mouth, or on models, has only limited value. The same applies to the posterior section of the apical area, particularly in the mandible where models give no information.
The size of the separate sections of the apical area is illustrated by showing situations during the intertransitional period which correspond with observations from panoramic radiographs.
The position of the permanent canines and the mesiodistal angulation of the permanent incisors give an indication of the size of the anterior section of the apical area in the mandible and maxilla (Fig. 5-8).
The distance from the mesial surface of the tooth forming part of the permanent canine to that of the first permanent molar is representative of the size of the middle section of the apical area. In the mandible, the middle section is considered large if the unemerged premolars and permanent canines are rather far apart; and medium if they are close together, but not overlapping. In the maxilla, the middle section is considered large if premolars and canine do not overlap; and medium if they overlap slightly. In the mandible, the middle section is considered small if the canine and first premolar overlap each other vertically. If the overlapping in the maxilla on the panoramic radiograph exceeds a half premolar crown width, the middle section of the apical area is designated small. In addition to this, one has to also reckon in both jaws with the distance between first premolar and first permanent molar and the width of the second premolar crown. The distinction between the two jaws is related to their different morphology and size of the apical areas. Typical in that respect is that during formation, the maxillary canine lies close to the first premolar and to some extent overlaps it. (Fig. 5-9). With regard to the posterior section of the apical area, there is a significant difference between the mandible and maxilla; something that again relates to the shape of the jaws. In the mandible, the posterior section is described as large when there is room between the three molars, with no overlapping and if the third molar lies relatively close to the anterior border of the ramus. There should be no vertical overlapping of the second and third molars. A small posterior section is characterized by close packing of the molars, overlapping transversely and vertically, with the third molar located relatively far dorsally in the ramus. Moreover, the third molar is often abnormally angulated. If the maxillary second and third molars are in line, with room in between, then this section would be classified as large. If they are close together, and overlap a good deal (sometimes they stand almost one on top of the other), then the posterior section of the apical area is classed as small. The posterior section of the apical area is classed as medium in either jaw if its features lie between the criteria given above for the large and small sections (Fig. 5-10).
Fig. 5-7 Mesiodistal dimensions of the apical area in the mandible and maxilla subdivided into anterior, middle and posterior sections.
A, B In a 4-year-old child the anterior section of the apical area is formed by the region between the mesial surfaces of the developing parts of the permanent canines. This region can continue to increase in size in the maxilla thanks to the presence of the midpalatal suture; this is not the case in the mandible.
The middle section of the apical area lies between the distal border of the anterior section and mesial surface of the developing parts of the permanent first molar. For both mandible and maxilla this area cannot increase in size since bone a incapable of interstitial growth.
The posterior section of the apical area lies dorsally to the middle section and extends to include the maxillary tuberosity and the lingual tuberosity in the mandible (109). Through bone formation at both tuberosities the posterior section can gradually enlarge and in this way accommodate the molars which successively are added to the distal of the dental arches.
C, D At ten years of age the same principles apply to the division into anterior, middle and posterior sections of the apical area as was outlined above for the 4-year-old. Modification is however necessary to allow for the vertical movement of the permanent first molars and canines.
E, F In the adult 21 years of age, the borders of the regions are slightly mesial to the roots of the first molars and the canines. The canines are fully formed and in occlusion. The size of the posterior section of the apical area and the space for the permanent molars depends on the dorsal growth which has occurred at the maxillary and lingual tuberosities.
(Van der Linden, F.P.G.M.: Facial growth and facial orthopedics. Quintessence Publ. Co., Chicago, 1986)