Tooth surface loss (TSL) can present in various clinical forms and has a wide range of aetiological factors. Dental erosion, attrition and abrasion are commonly observed by general practitioners, the first two often being seen in younger patients. The superimposition of TSL and malocclusion and/or tooth size and position discrepancies can compound the problem because of the coincident loss of form, function and aesthetics. It can also create difficulties in planning treatment options, with treatment strategies having to be drawn from multiple disciplines and integrated harmoniously to achieve long-term success. There are also other important issues to consider; treatment of tooth wear involves altering the vertical dimension of occlusion (VDO) and orthodontic treatment alters the position of the teeth, both often complex, lengthy and high cost procedures in their own right, never mind in combination. If the patient is young the cost of ideal treatment can be prohibitive and they will expect longevity from the treatment provided and materials used. These are conflicts which probably will require some form of compromised treatment being embarked upon. It also needs to be borne in mind that the protection of valuable remaining natural tooth tissue is sacrosanct and this puts pressure on the ethical practitioner to be as conservative as possible. It is therefore crucial in these cases to ensure that the patient is fully aware of any compromises chosen, the reason behind the choices made and to involve them in the decision making process itself. Fortunately with the advent of modern hybrid nanocomposite materials and innovative orthodontic and restorative techniques, treatment can be designed to be progressive in nature, with patient-led decision making. Success can be achieved at the straightforward end of the treatment spectrum yet can evolve to encompass more complex restorative work involving the skills of a dental technician if required. All of these factors had to be considered in the case presented here.
The case study illustrates a simple multidisciplinary approach through the use of occlusal therapy combining centric relation direct composite build-up of worn occlusal surfaces of upper and lower molars and premolars to re-establish an acceptable and comfortable VDO. The resulting increase in anterior space was utilised by retracting the spaced, severely worn upper incisors with removable aligners (IAS Inman Aligner and IAS Clear Aligners). This enabled aesthetic restoration without the need for invasive reduction by placing direct labial nano-hybrid composite veneers using a modified (untrimmed, full coverage) version of a clear matrix technique described by Mizrahi .1
The patient first approached me when he was 21 years old, complaining of unsightly gaps between his front teeth. There was a relevant family history as he had an identical twin brother who also had a spaced anterior dentition. Extraorally he presented with a reduced lower face height. Intraoral examination showed evidence of moderate occlusal wear through to dentine occlusally on several upper and lower molars and premolars. The upper incisors were severely worn and had lost almost half of their clinical crown length. Microdontia was ruled out, but the presence of diastemata indicated an imbalance between the jaw size and the size of the teeth. There was no serious frenal interference. The palatal surfaces of the upper incisors and the edges of the lower incisors were reasonably intact and there was a class 1 incisor relationship and no deep bite. The labial surfaces of all the teeth were unworn and the dentition unrestored. The upper canines were also worn and tilted slightly labially. It was possible to identify an anterior slide of the mandible, functional contacts on the posterior teeth and an absence of anterior guidance. There were no dietary abnormalities yet neither was he aware of any bruxist activity, although he admitted a severe nail biting habit. A diagnosis of premature anterior attrition in the presence of unfavourable canine geometry coupled with non-tooth contact parafunction was made. The patient vanished for two years, then returned, eager to commence treatment. Study cast comparison was able to demonstrate that there had not been any appreciable change in the clinical situation during that time, possibly attributable to a decrease in the rate of wear over time as the surface area of the teeth in contact increases 4.
Aims of treatment
- To create a mutually protected occlusion where the anterior teeth disclude the posterior teeth in all excursive movements of the mandible
- To avoid any preparation to the teeth whilst providing treatment according to sound biomechanical principles
- To prevent further pathologic wear of all teeth and to cover all exposed dentine
- To securely retain for life the positions of the upper incisors after orthodontic movement
- To improve the aesthetics and restore the patient’s confidence in the appearance of his smile
- To perform the treatment in a sensible time frame and as cost effectively as possible
- To re-establish a stable posterior occlusion at an increased VDO using centric relation and simple direct composites bonded onto the occlusal surfaces as an occlusal deprogrammer to discourage the anterior slide and allow the mandible to go back. This will also create space for the orthodontic phase.
- To retract the upper anterior teeth with removable aligners by a sufficient amount to enable their subsequent restoration to aesthetically acceptable mesio-distal dimensions and to create interproximal contact, but not so much as to encounter a problem with soft tissue squeeze. This would take approximately three-four months during which time the patient would be accommodating to the new VDO established in phase 1. This will eliminate the need for invasive reduction of the incisors during the next phase.
- To recreate the incisal anatomical form using direct nano-hybrid composite labial veneers. Precision in form will be assured by using a full clear silicone stent made over a diagnostic wax-up, with the wearing of a pre-evaluative temporary to assess patient comfort and satisfaction.
- To retain the teeth in their new positions for life using a palatal wire bonded retainer locked into the composite veneers for added flexural strength.
The worn dentine and enamel on the occlusal surfaces of the upper and lower molars and premolars was covered and restored to original morphology with acid etch bonding and direct placement of nano-hybrid composite (Venus Pearl – Heraeus Kulzer). Even contacts were established in centric relation (not done definitively as the final adjustment of the occlusal scheme was performed later after the establishment of the anterior guidance). The increase in the VDO anteriorly was approximately 2mm.
A standard IAS Inman Aligner was fitted to the upper arch with the aim of retracting the incisors. This occurred over a four-month period, with IAS Clear Aligners used for refinement of position at the end. During this time the patient accommodated very well to the new VDO. The 3D printed model of the predicted outcome of the orthodontic phase proved doubly useful; first for consent, but also because a wax-up of the composite veneers could be performed on it in order to see if the retraction predicted would allow the subsequent placement of appropriately sized composite veneers which would have interproximal contact. Once the incisors had been retracted to the pre-planned position, an accurate wax-up was made on a study cast and a full coverage clear silicone matrix, strengthened by 1mm Essix Ace retainer material sucked down over it, was made1. As the whole procedure was additive and as it would make a profound difference to the patient’s appearance, a pre-evaluative temporary in a temp crown and bridge material was made. This was worn for a day and night and proved a functional, aesthetic and phonetic success, giving confidence when it came to the build-ups that the plan was achievable. The thickness of the temporaries was visualised on removal and they were retained for use as a guide to estimating the volume and distribution of composite to load into the matrix. The composites were done individually using the full coverage matrix, with a single enamel shade of Venus pearl (A2 Incisors, A3 Canines) over a small pyramidal build-up5of dentine shade OLC Venus pearl. Adjacent teeth were protected with PTFE tape during placement and the restorations finished on the labial surface with a combination of Sof-Lex discs and rubber composite polishing points and wheels. The palatal surface was left unfinished.
An Essix retainer was made on the spot for the patient to wear for a week while a lab-fabricated palatal wire splint was made. At the fit stage, oval undercut cavities were prepared in the composite on the unpolished palatal surface into which flowable composite (Venus Diamond Flow – Heraeus Kulzer) was run as an adjunct to the etching and bonding of the wire to a large palatal area on each tooth.
The treatment proved to be a successful, cost effective choice for the patient, primarily due to accurate planning, realistic expectations, good compliance and avoidance of excessive laboratory fees. At six month recall, there is no evidence of marginal breakdown of the composite and the wire is still bonded and preventing relapse. The shape of the anteriors is now established and can be copied later if a move to ceramics is ever considered. In this type of additive case where there is no labial enamel erosion or thinning, ceramics are very much a second choice material since veneering or crowning necessitates enamel preparation to get good margins for the technician to work to in order to avoid over-contouring the restorations. In addition, crowning would have made reliable acid etch bonding of a retention wire impossible on the palatal side and macro-retention grooves in the palatal ceramic surface would necessitate more aggressive palato-incisal preparation to make sufficient space so as not to weaken the ceramic. Ceramic veneers would fare no better as their palatal margins would be right on the line of the bonded retainer and the bonding footprint for the wire to enamel would be much reduced, both increasing chances of failure.
The flexural strength of an incisor comes primarily from the labial and the palatal enamel 3which was left intact in this case. High strength composite bonded over both the unprepared labial and palatal enamel surfaces gave an optimal biomechanical result as the flexural strength of the incisors will have been substantially increased. This should reduce the chances of marginal breakdown of the composite in the long term. To further reduce flexural stresses on the upper incisors, the small ledge created by the bonded wire acts as a vertical stop for the lower incisors to occlude against, favourably transmitting forces down the vertical axis of each tooth 2.
The psychological impact of the treatment has been substantial. There was a total transformation of his appearance and smile, with a noticeable effect upon the patient’s self-confidence. The patient’s identical twin has followed his brother’s treatment closely and it is looking like I might need to repeat the process all over again! If not, we have a good ‘control’ subject for the future in order to observe what might have happened had my patient not had this treatment.
- Mizrahi, B. 2004. A technique for Simple and Aesthetic Treatment of Anterior Toothwear. Dental Update(31)109-114
- Mizrahi,B. 2005. The Dahl Principle: Creating Space and improving the biomechanical prognosis of anterior crowns. Quintessence International. 37 (4) 245-251
- Magne, P., Magne, M., Belser, U.C. 2007. Adhesive Restorations, Centric Relation, and the Dahl Principle: Minimally Invasive Approaches to Localized Anterior Tooth Erosion. J. Esthet. Den.,(2) 260-273
- Seligman, D.A., Pullinger, A.G. 1995. The Degree to which dental attrition in modern society is a function of age and of canine contact. Orofac. Pain, 9(3):266-75
- Qureshi, T. 2016 Jan/Feb. Technique Tips – Composite Edge Bonding – The Reverse Triangle Technique. Dental Update. 95,96.