RESTORING ESTHETICS AND ANTERIOR GUIDANCE IN WORN ANTERIOR TEETH
A CONSERVATIVE MULTIDISCIPLINARY APPROACH
FREDERICK MCINTYRE, D.D.S.
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ABSTRACT
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Background. Developments in adhesive dentistry have given the dental profession new restorative materials and technology to restore esthetics and function to the worn anterior dentition. This article illustrates, through a clinical case study, the clinical requirements for restoring esthetic harmony and functional stability to the worn anterior dentition.
Case Description. The author presents the case of a 24-year-old man who sought esthetic dental treatment because he was unhappy with the appearance of his maxillary anterior teeth. The review of his dental history revealed that he ground his teeth at night. The author performed a complete evaluation of the causes of the patient’s bruxism and created a diagnostic preview to, among other things, develop the relationship between the condylar and anterior guidance and to establish the esthetic requirements for the final restorations. Treatment included periodontal recontouring, tooth preparation and placement of temporary and then permanent restorations; the patient also was given an occlusal guard to protect the restorations against future bruxing.
Clinical Implications. Whatever the cause of occlusal instability, it is important that the restorative dentist be able to recognize its signs—such as tooth hypermobility, tooth wear, periodontal breakdown, occlusal dimpling, stress fractures, exostosis, muscle enlargement and loss of posterior disclusion. When restoring the worn dentition, the clinician should bear in mind the five P’s: proper planning prevents poor performance.
Esthetic dentistry has created a revolution in dental materials and technology. Our health- and beauty-conscious society, with the largest discretionary income in history, has created an ever-increasing demand for esthetic dental procedures. Many patients seek esthetic dental care because of worn dentitions (Figure 1
). Unfortunately, in the past, esthetic dentistry publications, lectures and continuing education courses placed little emphasis on the relationship between function and esthetics. But today’s esthetic practices recognize the importance of restoring both function and esthetics.
Providing esthetics with the correct anterior guidance is the key to long-term occlusal stability. The blending of conservative esthetics with the traditional science of occlusion is creating a new standard of care for dental patients. This article presents a conservative multidisciplinary approach to restoring esthetics and function in a patient with a worn anterior dentition.
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DIAGNOSIS
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Diagnosis is paramount in developing a treatment plan and sequence of treatment that will yield a predictable, stable, functional and esthetic result. A comprehensive examination, mounted diagnostic casts and other associated diagnostic instrumentation are necessary to determine the causes of instability and the treatment that will create stability and reduce wear of the dentition. In restoration of the worn dentition, the most important factor for success is the recognition of the causative factors and necessary restorative corrections.
The case presented in this article is that of a 24-year-old man who was seeking esthetic dental treatment because he was unhappy with the appearance of his maxillary anterior teeth. He was unaware of the causal relationships between the severe wear of his anterior teeth and the alteration of his smile. His concerns were esthetic, not functional. During the review of his dental history, he related that he ground his teeth at night.
Bruxism was classified by Ramfjord and Ash1 into two categories: centric (vertical loading during waking hours) and eccentric (grinding into lateral excursion while sleeping). There are a number of reasons why people clench and grind their teeth, and they generally fall into one of two categories: psychological and odontogenic. A number of studies discuss the etiology of bruxism and the controversial role that teeth play in the process.1–4,10,12–14
Whatever the cause of occlusal instability, it is important that the restorative dentist be able to recognize its signs. It is these signs that give the clues to the location and extent of damage to the teeth and the corrections that are necessary to reduce the wear caused by the patient’s bruxism. By recognizing signs of instability such as tooth hypermobility, tooth wear, abfractions, periodontal breakdown, occlusal dimpling, stress fractures, exostosis, muscle enlargement and loss of posterior disclusion, the restorative dentist can interpret the wear patterns and design a treatment that will protect the teeth or at least reduce the rate of wear.5 A dentist can recognize the signs of instability only by taking a thorough medical and dental history; conducting a complete head, neck and oral examination; and reviewing accurate diagnostic casts mounted on a semiadjustable articulator in centric relation.
To develop the functional stability necessary for the success of the treatment, the dentist must evaluate the determinants of occlusion. The muscles of mastication must be examined and palpated for tenderness. The condition of the temporomandibular joints, or TMJs, should be evaluated. A determination of the relationship of the condylar guidance to the anterior guidance has to be evaluated in cases associated with severe anterior wear.5 For the results of the patients’ treatment to be stable, the following criteria must be satisfied:
- – the patient can function from centric relation without occlusal interferences;
- – the TMJ can be loaded without tenderness;
- – there are centric stops anteriorly between the maxillary and mandibular anterior teeth;
- – anterior coupling allows for disclusion of the posterior teeth;
- – the teeth are positioned in balance with the tongue and facial muscles.5
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DEVELOPING ESTHETICS AND ANTERIOR GUIDANCE: DIAGNOSTIC PREVIEW
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Once the restorative dentist has a thorough understanding of the causal factors related to the damage of the patient’s teeth, he or she then can begin gathering the information necessary to create a diagnostic preview of the final restorations. The diagnostic preview will be used to develop the relationship between the condylar and anterior guidance; to establish the esthetic requirements for the final restorations; to create templates for periodontal surgery, tooth preparation and temporization; and to set up the incisal guide table on the articulator.
In many cases, dentists overlook or misunderstand the importance of establishing anterior guidance.
I created the diagnostic preview for this patient on the Denar Combi articulator (Waterpik Technologies). I used this articulator because it allowed for a more precise mapping of the condylar movements by means of a stereographic tracing technique (Figure 2). The maxillary cast was mounted on the articulator using a spring bow, and to ensure that the technician would have an accurate representation of the incisal edges to the pupillary line, I used the Behren Hanau Clinometer (Waterpik Technologies) to transfer the relationship to the articulator (Figure 3). To determine the size and shape of the maxillary central incisor, and develop the relationship of tooth size and shape for the lateral aspect and canine from a denture mold guide, I used a tooth-size indicator (Trubyte, Dentsply) (Figure 4).6
In many cases, dentists overlook or misunderstand the importance of establishing anterior guidance. With this particular patient, establishing anterior guidance was paramount to the success of the treatment. In cases in which the anterior teeth exhibit stability, anterior guidance can be developed using the existing guidance. However, in this case, the instability dictated an alternate approach. (As a point of interest, it has been suggested that anterior guidance can be developed using phonetics, computer generated axiography or cephalometric tracing.5)
For this patient, I used information gathered from the tooth size indicator and the cephalometric tracing to determine the maxillary incisal edge position of the central incisor (Figure 5). The cephalometric tracing is valuable for determining the interincisal angle, the position of the upper central incisors and the position of the lower central incisors and for facilitating a profile analysis.7 By transposing the length of the central incisor on the cephalometric in relation to the NA line, I established the position of the maxillary incisal edge and measured the overjet and overbite on the cephalometric tracing.
I used information gathered from intraoral photographs to establish gingival symmetry at the proper height on the diagnostic casts. Then, on the basis of information from the cephalometric tracing, I developed the diagnostic preview of the final restorations (Figure 6).
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CLINICAL TREATMENT
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The clinical treatment began after completion of the diagnostic preview, which allowed me to visualize the final restoration and to fabricate the templates for perioesthetic recontouring, tooth preparation and temporization.
The initial stage in the clinical treatment of the patient was periodontal recontouring. The severe wear of the anterior teeth had created eruption of the anterior teeth. The eruption patterns were varied owing to the unequal wear of the teeth, leaving gingival asymmetry. Using information gathered from intraoral photographs and from the diagnostic preview, I fabricated clear plastic templates for the periodontist, so that the gingival asymmetry could be corrected and the maxillary premolar could be exposed to improve the buccal corridor.
After healing, the patient was scheduled for tooth preparation. The design of the tooth preparation should encompass necessary reduction relative to tooth position and the requirements of the restorative material. The review of the cephalometric tracing indicated the need for a modification in preparation design that resulted in the conservation of tooth enamel. Because of the position of the teeth in the arch, facial reduction was reduced, while lingual incisal reduction was increased to accommodate the more labial position of the final restorations (Figure 7). Reduction of the labial surface of the tooth accommodated the manufacturer’s requirements for the material to circumvent the porcelain veneers’ propensity to crack,8 while conserving labial enamel. The lingual-incisal reduction satisfied the manufacturer’s requirements for the restorative material to prevent fracture as a result of occlusal loads. The use of the diagnostic preview and of the cephalometric tracing allowed for additional contour of the porcelain veneers, which is a key element in enamel preservation.9 After preparing the teeth, I took an impression and, using an anterior jig, a new centric relation record.
Temporization was accomplished by means of a template fabricated from the diagnostic preview and a resin-based composite material (Provipont DC, Ivoclar). The composite temporary restorations were placed with spot etching and allowed to remain in place for three months as a test of the vitality of the diagnostic workup. I provided the patient with a soft mouthguard at the time of temporization to protect the restorations during his bruxing episodes.
Photographs, the diagnostic preview and the articulator with the custom anterior guide were sent to the laboratory for use in fabricating the final restorations (Figure 8). Bruxism may continue even after the teeth have been repositioned to reduce wear and to establish esthetics and a new anterior guidance.11 Therefore, after placing the final restorations, I provided the patient with a hard acrylic occlusal guard to protect the restorations during his bruxing episodes.
Many steps are involved in creating restorative excellence in a case such as this. When restoring the worn dentition, the clinician should bear in mind the five P’s: proper planning prevents poor performance.
The use of the diagnostic preview and of the cephalometric tracing allowed for additional contour of the porcelain veneers, which is a key element in enamel preservation.
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CONCLUSION
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Advances in dental materials and technology have given practicing dentists the ability to create beautiful smiles for their patients. In doing so, dentists have the responsibility of developing proper form and function to protect the integrity of the masticatory system. Dentists must blend the new materials and technology with traditional functional concepts to be successful. As the case presented here demonstrates, this combination of innovation and tradition is achievable with careful planning.
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FOOTNOTES
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Dr. McIntyre is a clinical associate professor of restorative dentistry; the director, Postgraduate Prosthodontics; and the director, Esthetic Dentistry Education Center, University at Buffalo, State University of New York, School of Dental Medicine, 222 Squire Hall, Buffalo, N.Y. 14214. Address reprint requests to Dr. McIntyre.
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REFERENCES
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- Ramfjord SP, Ash MM, eds. Occlusion. Philadelphia: Saunders; 1971:177–82.
- Ramfjord SP. Bruxism: a clinical and electromyographic study. JADA 1961;62:21–44.[Medline]
- McLoughlin PJ. Clinical strategies to help patients reduce jaw clenching and bruxing behaviors. Int J Orofacial Myology 1990;16:13–7.[Medline]
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- Dawson PE. Evaluation, diagnosis and treatment of occlusal problems. 2nd ed. St. Louis: Mosby; 1989.
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- McNeill C. Science and practice of occlusion. 1st ed. Chicago: Quintessence; 1997:341–7.
- Magne P, Kwon K, Belser UC, Hodges JS, Douglas WH. Crack propensity of porcelain laminate veneers: a simulated operatory evaluation. J Prosthet Dent 1999;81:327–34.[Medline]
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- Rugh JD, Barghi N, Drago CJ. Experimental occlusal discrepancies and nocturnal bruxism. J Prosthet Dent 1984;51(4):548–53.[Medline]
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ABSTRACT
DIAGNOSIS
