Progressive wear of the dental hard tissues is a physiological process that occurs as a part of natural ageing. ‘Pathological tooth wear’ is a diagnostic term commonly used to describe a pattern of tooth wear which may be deemed excessive given the patients age. As our patients are now living for longer and retaining their teeth into their advanced years coupled with more recent changes in lifestyle, food and beverage consumption habits, it is not uncommon for a general dental practitioner to see several cases of pathological tooth wear on a weekly basis, on patients of all ages.
The successful management of a patient with pathological wear requires not only an understanding of how to accurately assess and diagnose the condition, but also a clear appreciation of how to plan treatment provision, including the delivery of effective preventative care. Where active intervention is required, there is a need to understand the reasons for the prescription of restorative care, and indeed when and how it may be most effectively achieved.
Active restorative management of pathological tooth wear is usually Minimal intervention, optimal predictability indicated where there may be aesthetic concerns, matters relating to reduced functional capacity, symptoms of discomfort, or indeed where the rate of wear for a patient may be deemed highly excessive by either the dental patient or practitioner. Restorative care should aim to not only restore function and aesthetics, but also provide the mechanical stability to the occlusal scheme. Conservation of the hard tissues, predictability and contingency planning are key determinants of success.
As restorative care may involve marked changes in both form and function, which may sometimes prove to be beyond the adaptive potential or the acceptability of a patient, restorative treatment should be provided with minimal intervention and optimal predictability. Historically, restorative care has been delivered by the means of conventionally retained indirect restorations, which require a type of preparation design to provide the required retention and resistance form and of course, space for the restorative material. However, these restorations often require the copious removal of further hard tissue, which may indeed compromise pulp vitality, are costly, require the fabrication of provisional restorations and the applied changes are irreversible. Furthermore, failures may be catastrophic, offering little by the means of contingency planning.
Logically, a predictable restorative approach would be one that would permit the replacement of lost hard tissue, with an effective material, without the need to remove sound tissue, and thereby reverse the effects of tooth wear. However, occlusal compensation and adaptation that often occur with the worn dentition (in order to preserve function of the masticatory system), renders the latter as an over-simplistic ideal.
With our advances in the knowledge of practical occlusion and with the predictability of resin adhesive technology over recent years, the above ideal has become partially possible, with the use of direct resin composite restorations.
The above material provides a minimally invasive, additive approach to the restoration of worn teeth, which surpasses the need of provisional restorations and where acceptable aesthetic outcomes can be attained. Should intolerance be expressed or modifications required to the prescribed occlusion there remains the possibility of adjustment or in the extreme, complete reversal. However, there are certain parameters that must be observed, in order to attain predictability with this material and its method of application. These
include the availability of copious, high quality enamel, optimal moisture control and the need for operator skill. There is also a need to apply increments of a suitable dimension to avoid de-bonding or fracture and a need to attain occlusal stability so as to avoid excessive mechanical forces.
An effective and efficient use of direct resin composite to restore can be applied very successfully in the anterior segment where occlusal forces are relatively lower than further posteriorly. In the case shown by figure 1(a) & (b) the application of a ‘canine rise’ to worn canines offers disclusion in excursive movements for the posterior segments thereby helping to prevent the further wear of these teeth.
With the growing acceptance of relative axial passive tooth movement to reestablish occlusal contacts (commonly referred to as the Dahl phenomenon), the restoration of localised wear can be addressed in a completely noninvasive manner, providing certain parameters are fulfilled. This is shown in figure 2 (a)–(e).
In cases where there is posterior wear the relative compressive strengths of these materials, coupled with their tendency towards chipping, bulk fracture, and wear may be factors which require further consideration when contemplating the restoration of worn posterior teeth. However the occlusal prescription and the tolerance of the patient can be ascertained with ‘centric stops’ in direct composite resin material with a view to use more durable
indirect restorations to replace the composite on posterior teeth on the longer term.
Figure 3 provides an example of a more extensive case of a 67-yearold male patient, with concerns relating to the appearance of his worn dentition and who also wished to explore means by which his central diastema could be closed with the colour of the teeth uniform. There was pathological tooth wear also present posteriorly. Following the build up of the anterior teeth, ‘centric stops’ were placed on the posteriors.
Following the attainment of patient consent, a silicone key was made from the diagnostic wax up, to record the established palatalocclusal form, using President Putty (Coltene, Whaledent). Isolation was established using Optragate, (Ivolclar). Teeth were restored using pre-warmed resin composite, G-aenial Anterior (GC Europe), applied in a layered manner using shades AE and Dentine A3.5. Resin was applied across the labial surfaces, in an attempt to mask the underlying fluorosis.
Gross polishing was delayed for 30 minutes to permit dark polymerisation, achieved using a combination of diamond and tungsten carbide finishing burs, a combination of Green and White Durastones (Shofu) and restorations polished with Astropol and Astrobrushes (Ivoclar, Vivadent). Figure 3c shows a facial view of the post-operative result taken two years after initial resin placement. This outcome has been attained without any subtraction of the compromised hard tissues. It has also been possible to close the diastema, and by carefully applying the material, attain the desired colour consistency.
This case reflects the versatile application of resin composite, placed in a direct manner to treat a variety of demanding clinical problems, with minimal intervention.
In an analogous manner, worn lower anterior teeth may also be effectively treated using this material. Application of the material using the ‘injection molding’ technique has the merits of simplifying the process of resin application to gain predictable results, as shown by figure 4a (preoperative view) and figure 4b(five year post-operative view), treated using Gradia (GC Europe). Five years post restoration no further remedial work has been undertaken to these teeth, demonstrating acceptable medium term results, both functionally and aesthetically, where placement parameters have been closely observed.
The technique of injection molding involves the injection of pre-warmed resin composite into a modified stent, constructed on a duplicate model following the fabrication and acceptance of a diagnostic wax up. Figure 6 shows an example of a modified PVC stent, constructed using a vacuum formed 0.5mm rigid thermoplastic PVC blank (Acorn Plastics). The stent has been extended 3mm beyond the gingival margin, to maintain structural integrity. Interpromixal slits have been made to extend past the contact area, which permits the insertion of a matrix. Vents have been cut into the stent to permit the insertion of a pre-warned resin composite compule. For cases of more advanced lower anterior wear, initial ‘dentine cones’ may be added, followed by the placement of the stent and the subsequent application of an appropriate enamel shade, permitting layering to attain a desirable aesthetic outcome.
References available on request.