Adapting to Treatment Complications: Stronger is Not Always Better!
Re-evaluation and further analysis ensure long-term success
By Leon Hermanides, CDT, NHD Dent Tech
Despite high levels of training and experience, a functional diagnosis may not always be clear cut nor fit neatly into one category. The following case demonstrates the principles of risk-based treatment planning and the difficulty in identifying and evaluating all of the evidence in an effort to ensure success in our restorative treatment plans. However, it also offers a strategy for addressing an unexpected treatment complication without increasing the patient’s risk for future problems. Often a change in restorative materials or a change in restorative options requiring increased tooth reduction will follow any failure in an indirect restoration. This will, however, increase a patient’s risk of catastrophic failure to the tooth without refining the diagnosis and finding better ways to manage the patient’s inherent risk profile.
The patient, a 35-year-old male, was concerned about the chipping and thinning of his maxillary incisal edges and unhappy with the appearance of his teeth (Figure 1 and Figure 2). His medical history was noncontributory. His dental history raised concerns, possibly indicating symptoms related to a functional diagnosis of Constricted Envelope.1 He reported that an equilibration had been initiated about 10 years prior but was never completed because during the process, the patient experienced increasing discomfort, tension headaches, sore teeth, and jaw problems. He reported that he clenches his teeth and stated, “When I bite my teeth together I do not feel them all touch.”
Over the last five years, the patient noticed his front teeth becoming thinner and chipping (Figure 1 through Figure 3) and he experienced discomfort when chewing foods such as bagels, hard breads, and chewing gum. He noted that he would sometimes awaken with an awareness of his teeth and when his nightguard came out in the morning, his front teeth were the only teeth contacting in the MIP (maximal intercuspal position).
Wear facets were present on the facial aspects of the mandibular anterior teeth with distinct ledges on the palatal surfaces of the maxillary anterior teeth, and minor (less than 1 mm) posterior wear was noted (Figure 3 and Figure 6). The areas of moderate attrition from normal forces were consistent with a diagnosis of a constricted chewing pattern.
The destructive wear on the front teeth (thinning) was not associated with the lateral excursive movements of parafunction. Although a parafunctional habit could not be completely eliminated in the diagnosis, the active destruction of the incisors resulted from the adaptation typically seen with a constricted chewing pattern.
Considering the patient’s diagnosis and risk profile in these four major areas, the various treatment options were carefully evaluated and selected. Initial treatment consisted of orthodontic therapy to correct the anterior rotations, tip the maxillary incisors out facially, and intrude the mandibular anterior teeth. Sufficient inter-arch space was created for both post-orthodontic occlusal equilibration and restoration of the anterior teeth with minimal tooth preparation (Figure 7).
A six-month stabilization period was advised after orthodontic therapy and before equilibration or restorative procedures were initiated. After stabilization, the patient wore a Kois deprogrammer for 3 weeks and an occlusal equilibration was performed utilizing the deprogramming appliance.2
Ultimately, restoration of the anterior teeth and the worn-away tooth structure was accomplished with enamel-bonded feldspathic veneers. With a view to management of any potential parafunction, flattening the guidance on the anterior restorations was recommended to minimize the risk of porcelain failure.
The preparation design for restorations on the palatal of the maxillary incisors was determined by the existing wear facets, which minimized any further tooth reduction (Figure 8 and Figure 9). The cingulum of the incisors remained intact, and the facial and proximal preparations were maintained mostly in enamel. The slight spacing created between the maxillary anterior teeth, when they were flared labially in the orthodontic phase, required proximal preparation of the maxillary incisors. This design reduced the biomechanical compromises to the teeth.3 Spaces distal to the cuspids were not closed as the patient agreed they were not an esthetic compromise.
The cervical margins were prepared to remain slightly supra-gingival and entirely in enamel, (Figure 9) a preparation design that significantly favors a transparent restorative material such as feldspathic ceramic, layered on refractory dies. With the creation of the “contact lens” effect in the final restorations, the margins were not visible after bonding (Figure 10).
When the prepared tooth is not substantially discolored, a translucent all ceramic restoration can be prescribed, such as the refractory veneers used to restore this case. It is, however, vital that the color of the prepared teeth be communicated to the ceramist to help develop a ceramic layering strategy. The ceramist will be able to mask most underlying discolorations or use translucent materials to blend margins prepared supra-gingival as appropriate (Figure 11).
This communication is easily managed by taking a digital photograph of the prepared teeth with a matching shade tab clearly visible. As the tooth preparation procedure will typically dehydrate the abutment teeth, allowing a few minutes for rehydration will help to clearly communicate the extent of any discoloration.