RECONSTRUCTING A NATURAL SMILE WITH DENTURES. R.J.C.Wilding. BDS, Dip Pros. M.Dent. Ph.D. MSc.

Introduction

The position of the maxillary anterior arch, and the arrangement of the individual teeth make the most crucial contribution to the appearance of the face. The teeth are not only an important component of facial appeal. They give each face a unique identity, just as eyes, nose, and skeletal proportions make each face distinctive and easily recognised. When the teeth are extracted, more than just teeth are lost. The body image, vitality and sexuality are struck down. The artificial tooth replacements can, and should contribute to the distinction of each patient's face, just as the natural teeth did, and in the process go some way to restoring the lost body image. The goal in setting artificial teeth is quite simply to put them where the natural teeth were (Bissasu, 1992). The purpose of this article is to set out some of the readily available methods for reconstructing a natural smile. These methods apply at the jaw registration ("bite") stage or at the try-in stage.

Reconstructing the arch position

The residual ridges provide a reliable guide as to the arch size, shape and position (Brunton and McCord, 1993, 1994). The buccal plate of bone around the roots of maxillary teeth is quite thin and resorbs more than the palatal plate which is quite stable. So the whole maxillary arch should be set outside the crest of the residual ridge. Estimate the position of the incisal root apices and then allow for a normal root inclination of about 23 degrees from the horizontal plane of the face. This gives some idea of the original incisal arch position. Another useful guide is to set the maxillary incisor about 8mm anterior to the position of the incisal papilla, which remains a reasonably stable reference point. (Fig1a)

When viewed from the fitting surface the anterior teeth should normally be visible just outside the periphery of the denture. If you suspect that the arch of the previous denture is too far back, or the patient complains of poor lip support, check that the front teeth can be seen from the fitting surface. If in doubt, soften a length of periphery wax, flatten it about 2-3 mm thick and press it down over the labial surfaces of the teeth. If the lip looks better supported it is an indication that the whole arch need to come forward.

Figure 1a A diagrammatic representation of the correct position of the anterior denture teeth.	Figure 1b The consequences on lip support, of setting the anterior denture teeth directly over the residual ridges.

The mandibular incisors should be positioned just anterior to the residual ridge. If the necks of either the maxillary or mandibular denture teeth need grinding one might suspect that the arch is not far enough forward. This is a common error which occurs in the laboratory when the teeth are set directly over the arch. As a consequence the lower face is unsupported. In an effort to correct this, the patient may demand an increase in the vertical dimension of occlusion, and plumping out of the maxillary buccal flange (Fig 1b). This requests fails to correct the fundamental problem. A small arch with an excessive vertical dimension in occlusion makes a denture unstable and uncomfortable.

Figure 2a A narrow arch fails to support the lips and cheeks. It encourages an excessive vertical height to restore some fullness to the face.	Figure 2bThe arch is wider, the teeth further forward and the vertical height reduced. Appearance and comfort are restored.

Working to general principals of tooth arrangement

Tooth size matching face size

If the arch position seems good, look again at the tooth size. It is worth keeping a few sets of the anteriors you most frequently use so as to be able to replace one or two teeth, either larger or smaller, so that you can be sure you and the patient have made the right choice.

Smile line

It is not uncommon for the anterior teeth to be set up with the incisal edges on the same plane. (Fig 3a). The incisal edges should follow the curve of the lower lip. It may be necessary to lift both canines or bring the centrals down in order to reconstruct an appealing curve. It takes a few moments to push the laterals upwards and at the same time backwards so as to restore the proper dominant position of the central incisors. The instantly recognisable signature of youth, and beauty are prominent central incisors. (Fig 3b).

Figure 3a The standard anterior set up with all incisal edges level	Figure 3b A natural and youthful appearance is recaptured by making the centrals prominent and tucking the lateral behind. The incisal curve should follow the line of the bottom lip

Altering the impact

For a softer more feminine appearance, rotate the central incisors slightly away from each other and rotate the lateral teeth in the opposite way. For a bolder more masculine appearance, place one incisor ahead of the other and allow the canines to be prominent (Fig 5a).

Figure 5a For a rugged, masculine appearance, place one incisor ahead of the other.

Anterior crowding

Some degree of incisal crowding is common. It is worth being quite bold about crowding anterior teeth. A degree of crowding which looks excessive on a laboratory bench looks surprisingly natural and acceptable in a patients mouth, viewed from the usual social distance. Care must be taken to create some sort of composition , with balance and harmony. The safest compositions are those which are bilaterally symmetrical(Fig 6a)

Figure 6aCrowded anteriors which are bilaterally symmetrical look excessively irregular when set up on the bench, but not when viewd at conventional social distance. The long axis of the teeth and the general arch from must be preserved.	Figure 6b Crowding of the anterior teeth can add both character and vitality to the face but must be done with care to retain a balanced composition.

The repositioning of the anterior teeth according to general principals can be done quite rapidly with great effect. But if the patients own distinctive appearance is to be recaptured, pre-extraction photographs will be required (Engelmeier 1996) .

Working to specific guides of tooth arrangement

Photographs showing the front teeth, even when the patient was a teenager give an indication of size and display. Often the picture is clear enough to reveal quite a distinctive arrangement which when incorporated into the set up is instantly recognised by the patient .

It seems best to set a few teeth at the jaw registration (bite-block) stage. You will need an extra half hour, but if you can set the six front teeth you will be that much closer to your goal at the try-in stage. When the six front teeth are in place it is the work of a moment to take a polaroid photograph with a close up camera. It is extraordinary how revealing a close up photograph is of errors in composition. The benefit in moving rapidly towards a really attractive and acceptable tooth arrangement, is many times offset by the cost and time of making the picture. A polaroid picture also gives the patient something to take home and look at, even before the try-in stage.

The emotional consequences of tooth loss

It is worth a short side-track at this point to remind us of that tooth loss caries with it serious emotional repercussions which have to do with loss of body image, vitality and sexuality (Fiske et al 1998). Many patients do not want to look in a mirror without their dentures in. Others keep the secret well hidden from a partner for large parts of their life. Other patients recall the despair of being wheeled down to an operating theatre without their dentures in. The loss needs to be recognised before our patient can proceed to anger and eventual reconciliation. If patients get stuck in this process the loss is buried, and with it the grief and resentment. This resentment may be a reasonably mild distaste for wearing dentures or it may be quite a strong aversion to dentures, to the point of feeling pain or nausea as soon as they are put in the mouth.

Some patients who have suffered this level of denture rejection have worked back, perhaps 20 years or more, to the days and months following the extraction of their teeth, and acknowledged that a deep wound, almost an invasion of their mouth had occurred. It is then clear that dentures made today, still bear the stigma of that invasion and artificial intrusion of yesterday.

Re-establishing the patients body image

Our own teeth are unique, in size, shape, arrangement and in the support they gave our lips and cheeks. If they had to go, the closer we could get the artificial teeth to our own, the more like our old self we would look and feel. As dentists, this would surely be our first request to a colleague making us a set of dentures. So it is worth spending some time with the patient, and photographs before they lost their teeth, so that as much as possible can be done to restore their former appearance. It does not matter how long ago they lost their teeth. With the exception of some wear, they would not have changed much in 50 years. Reconstructing an artificial dentition with pre-extraction records gives validity to the replacement teeth.

An example of the use which can be made of pre-extraction records is illustrated in Figure 4a and 4b. In a note of thanks after getting her new dentures this patient wrote "having lost my front teeth at a very young age, it was wonderful to recognise the smile I hadn't seen in many years"

Figure 7aA pre-extraction photograph of the patient aged about 16.	Figure 7bAfter reconstructing the smile in the 70 year old patient.

This strategy in no way replaces the emotional work of recognising and reconciling to the loss of teeth, but it certainly goes some way to making a denture more personalised, and therefore more acceptable than one which looks as though it came off the shelf.

When the patient is able to participate in the process of reconstructing their appearance, their attitude becomes more positive and they begin to "own" their artificial replacements. If we can help a patient to rebuild their body image, making dentures is a great source of pleasure and satisfaction.

Recommended Reading

Bissasu M ( 1992) Copying maxillary anterior natural tooth position in complete dentures.

J Prosthet Dent, 67(5):668-9.

Brunton PA; McCord JF (1993) An analysis of nasolabial angles and their relevance to tooth position in the edentulous patient. Eur J Prosthodont Restor Dent, 2(2):53-6.

Brunton PA; McCord JF (1994) Guidelines to lip position in the construction of complete dentures. Quintessence Int, 25(2):121-4

Engelmeier RL (1996) Complete-denture esthetics. Dent Clin North Am, 40(1):71-84

Fiske J, Davis D M, Frances C and Gelbier S. " The emotional effects of tooth loss in edentulous people. BDJ vol 184 , 90-94, 1998.