Inside Dental Technology
Complex Esthetic and Functional Rehabilitation with an Additive, Minimally Invasive Restorative Approach
Team work can help tackle a complex case
Treatment of extensive tooth wear can pose particularly complex challenges to the dental team. This is primarily due to the difficulty in determining the source of what is often a multifactorial etiology, as well as determining the diagnosis of tooth wear and the definitive management of the patient. Patients may seek initial dental care in an attempt to improve the esthetic appearance of their smile without fully comprehending the source, complexity, or problems associated with tooth wear. Typical symptoms that present with tooth wear include: poor esthetics; chipping/thinning and/or fracture of teeth, particularly incisal edges; dentinal hypersensitivity; reduced occlusal vertical dimension (OVD); and minimal tooth height. Other signs of tooth wear are: classic cupped erosive defects on occlusal surfaces and incisal grooving; broad concavities within smooth surface enamel; loss of enamel and dentinal exposure; and restorations “raised” from tooth structures.
With the development of adhesive bonding, the dental team has the means of restoring a patient’s dentition in a much more conservative manner using an additive approach. Advantages of adhesive restorations include the following: retention form and resistance form are irrelevant; enamel bonding is predictable; there is decreased endodontic risk; remaining tooth structure is maximized; and the approach is conservative and minimally invasive.
This case describes the concepts involved in a complex rehabilitation using both direct and indirect restorations with minimal biological risk to the patient.
The patient, a 41-year-old woman, presented with her chief complaint being the short nature of her teeth and resultant poor esthetics. She was particularly concerned about the extensive loss of tooth structure and the chipping of her teeth (Figure 1).
A comprehensive history and examination was performed. The patient had a history of bulimia nervosa, a condition that consists of recurrent episodes of compulsive binges (ie, consumption of large amounts of food) with or without self-induced vomiting or purgation. Due to the exposure of the oral environment to stomach acid, this resulted in erosion of all maxillary teeth and the mandibular anterior teeth.
The patient reported occasional bilateral masseter muscle tenderness. She realized her teeth had been wearing and her bite had been changing over the past several years. It appeared that the attrition was primarily due to chemical erosion rather than functional forces. The functional symptoms of clenching and muscle tenderness were secondary to the unstable occlusion that resulted from the erosion.
There was no decay found at the time of the clinical examination, but a number of fillings were defective; no periodontal problems were noted. Intraorally, the tooth surface loss was generalized, involving all teeth in both arches and extending into dentin anteriorly, where there was thinning and chipping of the incisal edge resulting in reduced clinical crown height.
Tooth-wear diagnosis requires a need to identify the factor(s) contributing to the condition, which may be difficult due to what is often a multifactorial etiology.1 Identifying these factors is important in order to preserve the remaining dentition and improve the long-term prognosis of any restorative treatment completed.
The patient was diagnosed to have tooth wear due to tooth erosion that had occurred when she was bulimic, with a secondary etiology of bruxism. Chronic exposure to acidic substrates had led to exposure of the dentin and chipping of the teeth, and the condition was exacerbated by the patient’s parafunctional habits.
Patients that present with generalized tooth wear often do not display a loss of OVD because the loss of tooth surfaces occurs at a slow rate, which allows time for alveolar compensation. However, in cases where the surface loss is active and rapidly progressing this may lead to loss of OVD, as alveolar compensation may not be keeping up at the same rate.2 In occlusion, the patient in the present case appeared to have a decreased lower face height due to a loss in OVD, which had not been fully counteracted by alveolar compensation (Figure 2).
The objectives of treatment were to:
- improve dentofacial esthetics
- restore OVD and improve occlusal function, establishing a stable position of maximum intercuspation with bilateral simultaneous occlusal contacts
- restore and protect structurally compromised and exposed dentinal teeth structures with minimal- or no-preparation designs to prevent further tooth erosion
The extent of the damage to the patient’s dentition necessitated a rehabilitative approach. However, in areas where tooth wear was minimal and where the patient had no concerns, management of the situation consisted of a preventative approach that included patient education and advice. The key to restorative success was to determine the primary etiological factor and institute an appropriate preventive program to deter further deterioration. This was also important when restoring the dentition, as treatment can fail if the causes of tooth wear are not addressed.
The extraoral examination allowed assessment of the amount of incisal display while the upper lip was relaxed (Figure 3) and while the patient was talking and smiling (Figure 4). This revealed that there was insufficient display of the teeth and that there was potential to lengthen the incisal edges of the maxillary teeth.
Following a comprehensive intraoral clinical and technical assessment, including diagnostic photographs, study casts were taken and mounted on a semi-adjustable articulator. In the laboratory, the technician created a diagnostic wax-up (Figure 5 and Figure 6), taking into consideration the requested esthetic changes communicated by the patient and clinician. The occlusal prescription included contouring the wax build-ups to provide bilateral, even contacts in retruded contact position. Furthermore, the treatment plan included providing anterior guidance, a canine-guided occlusion in lateral excursive, and protrusive mandibular movements with posterior tooth separation on dynamic mandibular movements.
Upon completing the diagnostic work-up, the treatment plan that was decided upon by the dental team in consultation with the patient included the following:
- Mandibular: direct resin composite build-ups on teeth Nos. 22 through 28 and coverage of dentinal-exposed areas on teeth Nos. 19, 30, and 31
- Maxillary: no-preparation restorations on teeth Nos. 2 and 5 through 12; minimally invasive onlay preparations on previously restored teeth Nos. 3, 14, and 15.
Mandibular Direct Composite Resin Build-Ups
Teeth Nos. 22 through 28 were prepared and a total-etch adhesive technique was used. Placement of resin composite was accomplished with the aid of a silicone matrix formed from the palatal anatomy established from the diagnostic wax-up (Figure 7). The use of the matrix allowed the placement of composite to form the palatal contour and incisal length of the teeth as planned from the diagnostic wax-up (Figure 8). This would enable minimal adjustment at completion of the restorations.
Maxillary Indirect Restorations
Prep-less or additive restorations were planned by the team for the majority of the maxillary teeth, as these were in a lingualized axial position and, furthermore, needed to be lengthened for ideal esthetics. Hence, there would be no need to prepare the teeth to achieve the desired outcome. Additionally, by not preparing the teeth, the restorations would be bonded mainly to enamel, away from areas that had dentin exposure on the incisal/occlusal surfaces.
For teeth that were previously restored, the clinician removed the restorations and completed tooth preparations to allow a path of insertion for the onlays (Figure 9). An impression was taken of the preparations and bite registration at the planned occlusal vertical dimension. A bonded functional esthetic prototype (BFEP) was spot-etched and bonded into position utilizing putty indexes made from the diagnostic wax-ups (Figure 10). This allowed the patient to assess a “trial smile” prior to completion of the final restorations (Figure 11). This transitional stage provides the patient time to accept the proposed new smile and also to assess the occlusal changes from the increase in OVD and occlusal stability over a period of weeks or even months.
The laboratory fabricated the final restorations with pressed lithium-disilicate materials (IPS e.max®, Ivoclar Vivadent, www.ivoclarvivadent.com) using a B1 LT ingot (Figure 12). The lithium-disilicate restorations were individually placed to assess marginal fit and contact points. The restorations were then placed with a clear try-in gel to display for approval prior to permanent cementation.
Because the ceramic restorations were thin, and had minimal retention due to minimal or no preparation, the cementation process required that the restorations be adhesively bonded with resin cement to reduce microleakage,3 and increase the fracture resistance of the restored tooth and restoration.4
A dual-cure resin cement was used for the posterior onlays, which were thicker in cross-section. The restorations were then adjusted and finished with ceramic polishing and finishing techniques. The margins were finished into an “infinity margin” (Figure 13) and polished with rubbers and diamond polishing pastes.
For the dental team, the aim of managing a worn dentition case should be to determine the etiological factors and institute an appropriate preventive program to protect the remaining tooth structures while restoring function, occlusal stability, and esthetics. Treatment planning entails understanding the etiological factors and includes the planning of the steps involved with the reconstruction of the dentition to meet both functional and esthetic requirements. A minimally invasive or prep-less approach is preferred, and the use of direct and/or indirect restorations can be utilized in reconstructing the lost tooth structures in an additive approach.
This article originally appeared in the June 2014 issue of Compendium of Continuing Education in Dentistry.
1. Bartlett DW. The role of erosion in tooth wear: aetiology, prevention and management. Int Dent J. 2005;55(4 suppl 1):277-284.
2. Berry DC, Poole DF. Attrition: possible mechanisms of compensation. J Oral Rehabil. 1976;3(3):201-206.
3. Sorensen JA, Kang SK, Avera SP. Porcelain-composite interface microleakage with various porcelain surface treatments. Dent Mater. 1991;7(2):118-123.
4. Burke FJ. Maximising the fracture resistance of dentine-bonded all-ceramic crowns. J Dent. 1999;27(3):169-173.
Team Diagnostics and Analyses Solve Difficult Cases
Joshua Polansky, MDC, BA
About the Authors
Christopher CK Ho, BDS (Hon), re-ceived his Bachelor of Dental Surgery with First-Class Honors at the Uni-versity of Sydney. He completed graduate training in the Graduate Diploma in Clinical Dentistry in Oral Implants at the University of Sydney, and a Masters of Clinical Dentistry in prosthodontics with Distinction from Kings College in London, UK. Dr. Ho lectures extensively on esthetic and implant dentistry and is involved with the evaluation and development of new dental products and materials. He is a member of the Planning Committee and a mentor and lecturer for the Oral Implant Diploma at the University of Sydney. He is a faculty member of the UCLA Masters in Implant Dentistry Certificate programs and is a senior visiting clinical teacher at Kings College. He has a referral-based restricted private practice in prosthodontic and implant dentistry in Sydney, Australia.
Bradley Grobler re-ceived his degree in dental technology from Technikon Kwazulu Natal in Duban. Mr. Grobler is a dental ceramist and part-ner In Oral Dynamics, a boutique dental studio, and specializes in esthetic and cosmetic dentistry, CAD/CAM, and implant restorations. Mr. Grobler lectures and conducts hands-on workshops locally and abroad for Ivoclar Vivadent as an opinion leader. In addition, Mr. Grobler has attended workshops with numerous master ceramists and is a Kois Center graduate and an executive member of the New Zealand Academy of Cosmetic Dentistry.