The teeth were almost perfect…

It should be stated from the outset: in order to avoid damaging consequences, tooth wear and erosion phenomena should neither be underestimated nor neglected. To deal with the problem, solutions that are both reliable and relatively uninvasive are now available - which is a relatively new development. Because they are relatively complex, these solutions are not always applied in all dental practices; they require improved techniques and more knowledge about the materials to be used plus an expert knowledge of dental bonding techniques. In the article “A rational and conservative approach to advanced tooth wear”(1), Alain Vanheusden, a professor in the Dental Science Department of the University of Liege, sets out the application and aftercare required for a long and precise procedure which makes it possible to treat these kinds of cases. The objective is clear: to restore masticatory function and give patients and their dentists their smile back.

For several years, the problem of tooth wear and dental erosion has plagued dentists - and some of their patients. In fact, "more and more young adults consult dentists due to tooth tissue loss of non-carious origin", explains Prof. Alain Vanheusden, head of the Fixed Prosthetics Department at Liege University Hospital. Is it a serious problem? It certainly has the potential to become one.

Among the individuals concerned the tooth enamel becomes worn to the point of disappearing and resulting in the exposure of the underlying dentine which wears away quicker than enamel. This loss of tooth tissue is a serious problem. It causes sensitivity, the tooth becomes fragile to the point of breaking and this results in a visible esthetic difference with regard to the height (size) of the tooth. Another potential risk is present, that of an imbalance in dental occlusion.

Dental occlusion refers to the fact that our jaws and teeth should fit together snugly but dental erosion can “erase” or modify the indispensable points of contact between the teeth of the two jaws. In time, this imbalanced occlusion alters masticatory function and dental esthetics. In some cases, imbalanced occlusion can cause a malfunction in the temporomandibular joint (this is the joint that enables the mouth to open and close). The possible consequences of this are symptoms such as pain, spasms, jaw clenching and headaches and all of this is caused by “worn” teeth in the first place!

Formidable enemies

Since the end of the 20th century most European countries including our own have seen a reduction in the incidence of tooth decay. This represents real progress from a public health point of view! “The effects of fluoride, dental health campaigns, and improvements in techniques used and conservative dental materials have proved fruitful”, states the head of department. Yet dentists, and the wider population should not be content merely to fight against tooth decay (and caring for gums), but they should also deal with those other enemies of teeth, tooth wear and erosion.

“The hundreds of scientific articles that have been published on this subject during the last five years show the extent to which the problem has become a major preoccupation for dental practices”, says Alain Vanheusden.  This increasing threat has been caused by a combination of factors. Firstly, thanks to more efficient and conservative treatments (conservative refers to the preference of dentists for preserving and saving teeth when possible) the average life-expectancy for teeth has increased. Because we are living longer we keep our teeth for longer and this means they are even more exposed to tooth wear or erosion.

Other causes linked to our lives and behaviour come into play here. Our stress levels, our dietary habits and our medicines all play a part in the phenomenon of tooth wear and erosion. Under the effects of stress we can grit our teeth and/or grind them involuntarily and sometimes even unconsciously particularly during sleep. This bruxism applies a mechanical force to our teeth but the latter are not equipped to definitively resist this force. “It is important to point out that the intensity of the forces exerted greatly exceed those that apply during mastication”, explains Prof. Vanheusden. Stress, which is a social phenomenon, is therefore indirectly responsible for oral health problems…

In addition, or in parallel with this, we consume a lot of acidic drinks which attack our teeth. The most common and undoubtedly the most destructive of these products is an internationally-known soft drink. “But lemon juice or other citrus fruits, products high in sugar and even wine have a corrosive effect on our teeth”, explains Prof. Vanheusden. In short, we create problems for ourselves and our teeth which among other things can be caused by dental misalignment leading to premature tooth wear.

The influence of stress and the impact of soft drinks

On a theoretical level, tooth wear falls broadly into three categories. Abrasion lesions indicate mechanical wear and tear caused by friction between an abrasive agent and one or more teeth. Attrition-type lesions result from inappropriate contact or friction between teeth. Finally, what is referred to as dental erosion covers dental tissue loss of enamel by acid dissolution without the involvement of microorganisms.

“Attrition and erosion are the most common and the most aggressive problems”, explains Prof. Vanheusden. “These are linked to two social problems: stress and excessive consumption of soft-drinks whose corrosive properties have been amply illustrated. These two factors can go hand in hand and become potentially dangerous. In any case, erosion and tooth wear sometimes lead to real situations of dental ill health, even among those who otherwise have good oral hygiene or who are still quite young”.

Tissue loss will vary according to the degree of advancement and the duration of the underlying causes of tooth wear and erosion. "In addition to sensitivity, more often than not it is generally for esthetic reasons that the patient in question consults his or her dentist", continues Prof. Vanheusden.

On the prevention trail

Phenomena of dental wear and its causes are probably not yet sufficiently well-known by the public. Traditionally, in Belgium, prevention is the poor relation of dentistry. It must be said that, in his practice, the dentist also manages care, treatment and follow-up care too. The importance attached to awareness or education that could lead to saving teeth is often reduced or limited. In addition, dental practitioners have been poorly trained in prevention and the difficulties associated with it. Finally, “in contrast with some countries, we do not have a large number of dental hygienists specialised in the important work of prevention”, states Prof. Vanheusden.

Another difficulty for dentists is the fact that tooth wear and erosion are complex phenomena. Once they are identified, treating them involves discovering the underlying causes in order to make the patients aware of them and to encourage them to make behavioral changes. This process takes time and is far from simple.

Given the challenges for the population, certain changes in diet are achievable without the need for a personal revolution.  On the other hand, the possible solutions to the problem of bruxism are more difficult to deal with. It is not enough for a dentist to tell a patient that he grinds his teeth during the night and that this is causing tooth wear in order for him to change his behaviour. A person can take care not to grind his teeth during the day but during the night is another matter entirely.

“Consultations with a psychologist could help to modify the patient’s stress levels and to help change the behavior that this stress causes. However, it is not always easy to advise a patient to adopt such an approach”, says Prof. Vanheusden with a smile.  Apart from dealing with stress levels, no other therapy is known that could help to deal with the problem of bruxism. “On the other hand, we know how to limit its consequences”, he continues.

This solution involves the wearing of what is called a splint. This is made of resin and is made from an imprint of the mouth of the patient and is therefore adapted to the patient’s mouth. The splint must be worn during sleep: it prevents the teeth from rubbing against each other by placing an obstacle between them. Nonetheless, this preventive measure, which is undoubtedly an important one, does not really solve the problem when tooth wear or erosion are too advanced or when they are caused by sources other than bruxism.

A change of philosophy

Dr Vanheusden’s article concerns a clinical case (case report): that of the complete restoration of the mouth of a 34 year old man. He was affected by severe generalized  wear (see photos). As well as the unseemly aspect which this gave to his smile, the patient suffered from dental sensitivity: this sensitivity increased when he ate or drank cold foods.  

The patient didn’t smoke and did not take any medication that might explain the worn state of his teeth. On the other hand, during his anamnesis (the questions asked by the practitioner) it was revealed that the patient consumed large quantities of a well-known sweet soft drink-up to one liter per day. Added to the erosive lesions caused by the drink in question, the patient used a hard tooth brush and an inadequate brushing method. To complete the picture, this man also had the bad habit of gritting his teeth during moments of stress or tension.  

Prof. Vanheusden’s treatment plan aimed to restore the anatomy, function and esthetic aspect of the worn teeth. It was also neccessary to protect the latter against any further tissue wear. This vast program was not the only objective set by the practitioner: “Recent developments in dentistry have led us to focus, where possible, on having a conservative approach. This means limiting any further reduction in the tissue levels that are already present”, he explains.  

At this stage, in order to fully understand how this approach is partially new it will be necessary to take a look at the recent history of dentistry. This historical detour concerns the “traditional” therapies suggested to patients suffering from this kind of problem. “When confronted by the problem of tooth wear, some practitioners try to temporize. For example, they suggest compensating for the wear by placing a composite (a kind of  dressing) on the tooth in order to fictitiously reconstruct it”, says the practitioner.

“In reality, this solution is similar to putting plaster on a wooden leg”, says Prof. Vanheusden. “The composite is far from being a solid enough material to resist problems. It certainly answers the sensitivity problem felt by patients but this is its only contribution. In addition, the composite placed on the tooth is quite voluminous and is often associated with renewed decay (under the dressing). Obviously, this causes the tooth to deteriorate even more”.

The other option with regard to more “traditional” dentistry consists of waiting while doing nothing... Once the wear is well-advances, the dentist suggests placing crowns on the teeth in question. These are kinds of shells (generally ceramic) which cover the teeth entirely and are designed to compensate for wear by giving a new external anatomy to the teeth.

However, in order to place crowns, it is necessary to cut into the tooth tissue. “Therefore it is a process that necessarily causes a further reduction in the tooth tissue. Very often, root canal work is also necessary requiring the fitting of a screw into the root which makes it more fragile and involves a risk of future fracture”, explains Dr. Vanheusden. For a long time, there was no other choice: in order to reconstruct teeth and give them back some “height”, only crowns were possible. But times have changed thanks to the appearance and development of a technique known as bonding.

A binding future

From here on, dental bonding techniques, which have been developing since the 1990s have made it possible to adopt another approach which is considered to be minimally invasive. “By using bonding techniques, we succeed in reconstructing teeth, restoring their anatomy and all this without reducing the tissue levels of the tooth any more than is absolutely necessary. Our objective consists in placing implants that are as light as possible, preserving teeth that are already worn and fragile without harming them any further”, explains Prof. Vanheusden.  In dentistry, this minimally invasive approach is a veritable revolution which is of great benefit to the patient.

For the young patient from Liege confronted by generalized tooth wear, this “conservative” philosophy which favors tissue preservation prevailed in tandem with a multi-disciplinary approach. The surgical techniques (with, for example, the fitting of implants) and prostheses (by bonding) were planned, combined and associated with the treatment plan.

In fact, the team from Liege did not invent the A to Z of the procedure applied to this patient. It was inspired by the approach applied by the Department of Dentistry of the University of Geneva (Switzerland) where Franscesca Valaiti works. She is the author of numerous publications relating to this non-invasive procedure. But Prof. Vanheusden added his personal touch to the procedures to be followed. He applied a variant procedure which, during one of the treatment stages, makes it possible to lighten the somewhat restrictive procedure followed by the Swiss team.  Without negatively affecting the treatment, the practitioner avoided a certain number of occlusal corrections which would normally have had to be carried out in the patient’s mouth.

Three stages, step by step

Unquestionably, restoring teeth as damaged as those of this patient requires a long treatment. “From the outset, the reasons we are applying the treatment must be clearly explained to the patient”, Prof. Vanheusden reminds us. The patient’s level of motivation is an important factor even if only because he must be willing to make the necessary changes to stop the phenomenon of tooth wear.

The treatment care is administered in three steps. During the first step, the occlusion problems are at the center of the therapy. At this stage, it is impossible for the dentist to know the height that needs to be restored and reconstituted exactly for each of the teeth concerned. An estimate has to be made. This procedure must be milimeter perfect. In any event, each space that modifies the architecture of the dental arches must be able to be tolerated by the patient.  This factor is what needs to be evaluated first.

Some erosion or tooth wear lesions have been known to cause a loss of what is called the “occlusal vertical dimension” (OVD). When teeth are worn, they do not interlock with the teeth corresponding to them when the jaw is closed. In some cases, this even causes some teeth to move, to “exit” the gum (known as overeruption). In short, the occlusion is disturbed. A new OVD needs to be established which prepares the way for “new teeth” which in time will be reconstituted to the “correct” height.

“During this first phase we advance by trial and error”, explains the practitioner. “First of all, a removable resin splint is made. This serves as a protective shield against tooth wear. Based on the plaster models used to make it, the splint brings about an occlusal elevation in order to compensate for the loss of OVD", continues the Professor (photos). The objective is to monitor the ways in which the patient reacts, that is to say how he tolerates the splint that is used to re-establish the new OVD. This point is essential: it means ensuring that the ceramic restoration fitted during the final phase of treatment will perfectly suit the individual in question.  

For three weeks the patient wears this splint which causes an increase in his OVD (from 1 to 5 millimeters). He notes how he is feeling on waking up including any contractions of masticatory muscles.  “In the beginning, it is a big change for the patient”, admits the practitioner. “But once the level of tolerance is validated, it becomes our value of reference, the one that we will use during the final restoration of the worn teeth”, he continues.

A provisional procedure that speaks volumes

The second stage can then begin. It leads to the fitting of provisional partial restorations. First of all, after the molding of the current teeth, the prosthetics laboratory makes what are called wax-ups. These wax models are made according to the indications from wearing the splint and the imprint of the mouth.

Once they are made, the wax ups give a precise idea of what each used tooth will look like once it has been restored, in a context where there will be a maximum amount of dento-dental contact between. From the wax ups, resin prostheses are then made. Thin and fragile, they restore the height to the teeth upon which they are provisionally bonded and where they will remain for several weeks. 

“At this stage we are still applying a transitional approach, but a more precise one by means of the splint.  Indeed, there is no longer any need for the patient to wear a foreign body between the teeth. The individual concerned will live and sleep with these prostheses made from the wax ups. These temporary restorations enable us to confirm that we have achieved a comfortable new OVD.  They validate the occlusal modifications which have been carried out and confirm the re-establishment of the different functions. Finally, they make it possible also to appreciate the esthetic benefit of the restoration of the dental morphology”, states the practitioner.

When the situation is adjudged to be stable and satisfactory, the final phase can be envisaged. Of course, any surgical treatment will have been carried out beforehand.

A “real"smile

“For the last step of the rehabilitation, we keep our progressive and prudent approach", states the head of department. The dentist removes the transitional resin prostheses by milling. He replaces them by facets and ceramic overlays which have been made in the prosthetics laboratory. These prostheses are bonded to the teeth. The new elements placed in the mouth continue to raise the worn teeth, to reconstitute them just as the previous resin did.

He continues, “We only proceed by dealing with 2 or 3 teeth at a time. This precaution allows us to keep our occlusal bearings”, he adds. In extreme cases of wear, as with this patient, the restorations involved both sets of teeth. However, it is possible to envisage a situation where only the most affected set of teeth are affected.

Then... the dentist’s work is finished and the patient has got back a real esthetically pleasing smile as well as adequate function.  Nevertheless, when the origin of the problem was an abrasion, the wearing of a protective night splint remains obligatory. After so much time-consuming, delicate and very expensive work (up to several thousand Euros), it would indeed be a “costly” to restart a process of tooth wear...

"The ceramic prostheses which have been fitted to the teeth are not intended to be subjected to excessive erosion. They are fitted on teeth that are fragile to start with. Continuing to take risks would be all the more regrettable because fresh erosion would rule out bonding techniques. The patients must therefore be aware, motivated and be actively involved in the follow-up to the development of their treatments", states the practitioner. In the case described by the article, one year after the treatment no complication was reported by the patient…

Current statistics show that this three-stage approach yields good results for up to five years, with a success rate comparable to the prosthetics techniques that were used before bonding changed the face of dentistry . “The numbers show that, even on very damaged teeth, bonding does not risk failure", insists Prof. Vanheusden. Are the techniques described here superior to “traditional" procedures ? For the moment, in the absence of sufficient experience, we cannot say yes. However, the head of the dentistry department is convinced that they are. “A crown is much more aggressive procedure than bonding: in order to fit a crown you need, for example, to remove 3 times more tissue near the gum than for a facet bonding. From a biological point of view, the bonded facets are much less aggressive. They represent immense progress making it possible to achieve great things even in very advanced cases”.

Currently, faced by the difficulties of treating cases of very advanced tooth wear, a large number of dentists prefer to send the patients concerned to university services such as that of Prof. Vanheusden. Others follow the training and retraining offered (for example in Liege), in order to become familiar with the procedure that needs to be scrupulously followed. Some are already applying this procedure. In all cases, what is important is that the message gets through: tooth wear or erosion must be treated as soon as possible in dental practices or by a specialized service. And even for critical situations there are efficient solutions. A demonstration perhaps that tooth wear does not win.

Vanheusden, Alain , Approche prothétique rationnelle et conservatrice d'usure dentaire avancée, in Revue d'Odonto-Stomatologie [=ROS] (2014), 43(3), 251-268 Septembre 2014.