High success rates have been reported for ceramic veneers, and all-ceramic crowns.1-5 These treatment modalities promote superior esthetics, and are used successfully when patients are diagnosed as being free of parafunctional habits, such as clenching and bruxing. Treating the bruxer however, presents the restorative dentist with the challenge of providing these patients with esthetic, as well as functional and long-lasting restorations.
Much controversy exists in attempting to define “bruxism.” It is classified into daytime and nocturnal depending on its temporal incidence, and it is assumed that the two types have different etiologies and different modes of treatment.6 While daytime bruxism is related to an emotional state, nocturnal bruxism is defined as a stereotyped movement disorder entailing grinding and clenching of the teeth during sleep.6 The exact etiology of bruxism is unknown, and several theories have been proposed, such as a dental occlusal disorder (occlusal prematurities or interferences)7 an anxiety disorder caused by stress,8 or a sleep or movement disorder.9 Lack of consensus exists regarding the diagnostic criteria and the treatment regimen.
The presence of any of the following signs and symptoms have been used in the past to indicate bruxism: wear facets, excessive occlusal wear, increased muscle tone and uncontrolled resistance to mandibular manipulation, hypertrophy of the masticatory muscles, increased tooth mobility, dull percussion sound from the teeth, muscle fatigue in the morning; muscle tenderness to palpation, temporomandibular joint (TMJ) discomfort or pain, teeth soreness to biting stress, pulpal sensitivity to cold, and audible sounds of grinding.7 Bruxism commonly occurs in children and adults and is one of the major etiological factors of myofascial pain and internal derangement of the TMJ. The prevalence of nocturnal bruxism is estimated to be between 6-20% or between 25-50% of the general population.6,9 The highest prevalence of bruxism is between the ages 20-50, with no gender differences.9
While treating the bruxing patient, the restorative dentist must consider the long-term ramifications of using less than ideal restorative materials. Although the mechanical properties of some of the new all-ceramic systems approximate that of metal-ceramic restorations, clinical evidence does not support their use while treating the bruxing patient. As a consequence of patients’ inability to control their parafunctional habits, inherent microcracks in the porcelain may propagate leading to porcelain fracture with a catastrophic failure of the restoration. A metal substructure will strengthen the restoration by acting as a barrier against the propagation of microcracks and by reducing tensile forces applied on the porcelain. Therefore, the use of a metal substructure will promote the predictability and the success of the restoration.10,11
Excessive occlusal wear may manifest itself in the loss of the vertical dimension of occlusion. Turner and Misserelian have categorized patients with excessive wear to three groups: category I-excessive wear with loss of vertical dimension of occlusion; Category II-excessive wear without loss of vertical dimension of occlusion; Category III-excessive wear without loss of vertical dimension of occlusion but with limited space.12 Patients who are classified as category I may require an increase in their occlusal vertical dimension. Esthetic and phonetic guidelines are used as diagnostic criteria to determine the amount of increase required for restoring the lost vertical dimension of occlusion. A minor to moderate increase may result in an adaptive response and may contribute to improving dentofacial esthetics and enhance force management of the masticatory muscles.13-16
If the patient presents with symptoms, such as joint or muscular pain, these symptoms must be eliminated prior to any restorative procedure. Therefore, a complete data collection which include–past medical and dental history, complete clinical and radiographic evaluations, an esthetic analysis, an occlusal analysis and a TMJ and masticatory muscles evaluations, and a diagnostic wax-up, is paramount for an accurate diagnosis. An accurate diagnosis will allow the clinician to provide the bruxing patient with the optimal treatment option.
A CASE REPORT
Data Collection, Diagnosis, and Treatment Plan
A patient presented to the clinic with the following chief complaint: “I don’t like the way my teeth look, I don’t like my smile, my teeth are short, and this makes me look old. I hate the gray color of my teeth, and I would like to have white bright teeth.” His past medical history revealed that he was in good health and that as a child he was treated with tetracycline. He reported nocturnal grinding of his teeth and occasional clenching during the day with no symptoms. In addition, he has reported that because he did not like his tooth color, he used extra-hard toothbrushes, attempting to remove the gray color of his teeth.
Using esthetic and phonetic diagnostic criteria, the patient was diagnosed with decreased vertical dimension of occlusion. At rest, the patient did not display any of his maxillary anterior teeth. When he smiled, the incisal edges of his maxillary anterior teeth did not follow the curvature of the lower lip leading to the display of a reverse smile line (Fig. 1).
The ideal length-to-width proportion of a maxillary central incisor ranges between 10/8 and 10/7.5.17 The patient displayed a lack of adequate length-to-width proportions of his central maxillary incisors, due to their shortness. In addition, the maxillary and mandibular anterior dentition displayed tetracycline staining. (Fig. 2). An occlusal analysis revealed that the patient did not display a mutually protected articulation. The anterior maxillary dentition displayed worn palatal and incisal surfaces, and the posterior maxillary dentition displayed worn occlusal surfaces. The anterior mandibular dentition displayed worn incisal surfaces, and the posterior mandibular dentition displayed worn occlusal surfaces. The extensive occlusal wear was attributed to the patient’s bruxing and clenching habits (Figs. 3 & 4).
Group-function articulation was present on the right side, and nonworking contacts were present on both the right and left sides. In protrusion, there was no disclusion of the posterior teeth (Fig. 5). These findings were attributed to the patient’s bruxing and clenching habits. The TMJs and masticatory muscles were asymptomatic. The patient demonstrated adequate oral hygiene and good periodontal condition. Pocket depths were no greater than 4mm. There was no pathological tooth mobility, and no furcation involvement.
Two sets of diagnostic casts were made using irreversible hydrocolloid. A kinematic facebow for locating the transverse hinge axis and mounting the maxillary cast is recommended if the dentist is considering altering (mostly increase) the vertical dimension of occlusion, and it was done in this case.15 A centric relation record was made for mounting the mandibular cast. A stereographic tracing may be used to program a fully adjustable articulator by fabricating the customized fossae analogs, as done in this case.18
Teeth #13-23 had relatively short clinical crowns. Esthetic and phonetic guidelines were used to determine that they should be lengthened incisaly. A composite mock-up was fabricated and adjusted in the patient’s mouth to capture the desirable length. An impression of the mock-up was made and used as a guide for the fabrication of the diagnostic wax up. A diagnostic waxup with a mutually protected articulation occlusal scheme was made using the second set of diagnostic casts with the occlusal vertical dimension increased by 3 mm at the central incisors (Figs. 6-8). The wax-up was used for the fabrication of the tooth-preparation guides and the provisional restorations. The combination of occlusal wear and mechanical abrasion presents the restorative team with limited tooth structure for the abutment preparation. Therefore, the use of a guiding template, fabricated using a duplicate of the diagnostic wax-up, is extremely important in order to prevent unnecessary loss of tooth structure, especially when one desires to maintain tooth vitality (Fig. 9).
Diagnosis is based on clinical and radiographic findings, as well as on the information obtained from the diagnostic wax-up. The patient was diagnosed with the following functional and esthetic problems:
Excessive occlusal wear on both the anterior and the posterior teeth, with probable decreased occlusal vertical dimension due to nocturnal bruxism and clenching,
Altered plane of occlusion with rotated and malpositioned teeth,
Posterior contacts in protrusion,
Bilateral nonworking contacts,
Group-function articulation on the right side,
Short upper anterior teeth with uneven incisal edges leading to a reverse smile line and to poor esthetics,
Moderate tetracycline staining leading to poor esthetics.
The following treatment plan was formulated using all diagnostic procedures discussed, and the patient’s chief complaints:
1. Oral hygiene instructions and prophylaxis as well as topical fluoride;
2. Replacement of failing amalgam restorations, and performance of root canal therapy as needed;
3. Construction of a heat-processed acrylic-resin occlusal device to be worn for a period of three months to evaluate the patient’s tolerance of the 3mm increase in vertical dimension of occlusion;
4. Preparation of all teeth for metal-ceramic crowns (with porcelain butt margins for teeth #15-25 and #33-43 and provisionalization, providing the patient with a mutually protected articulation,
5. Reevaluation of the restored vertical dimension of occlusion with the provisional restorations;
6. Restoration of all teeth with metal-ceramic crowns, providing the patient with a mutually protected articulation;
7. Construction of a heat-processed acrylic-resin maxillary occlusal device for use during sleep and during the day as needed;
8. Postinsertion and oral-hygiene instructions and placement in periodic recall and maintenance program.
Upon completion of the initial phase of treatment, a mandibular occlusal device was fabricated with a heat-processed acrylic resin and delivered to the patient. It increased his current occlusal vertical dimension by 3 mm at the incisors, providing him with a mutually protected articulation. A patient should wear the occlusal device for at least three months. After 10 weeks the patient showed no adverse signs or symptoms from wearing the occlusal device.
The teeth can be prepared and provisionalized segmentally, with the anterior segment from canine to canine prepared first. A Gelb-like occlusal appliance that provides posterior occlusal contacts in centric occlusion can be used for maintaining the new vertical dimension of occlusion between preparation visits.19 Use acrylic resin provisional shells, reline them in the patient’s mouth, and cement them with a noneugenol interim cement. Place the provisional restorations on all the prepared teeth, and let the patient function with the full mouth provisional restorations for 3 months to evaluate further his adaptation to the proposed vertical dimension, and to the new occlusal scheme (Figs. 10 & 11). The esthetics and phonetics of the provisional restorations, the soft tissue health, and emergence profile are evaluated at this stage (Figs. 12-14).20 The provisional restorations, which are a duplicate of the diagnostic wax-up, will be used as templates for the definitive restorations.
After six weeks of comfortable function in the provisional restorations, preparations were made for the final impression. At the time of impression making, all soft tissues were healthy (Figs. 15 & 16). Mandibular and maxillary full-arch impressions were made using an addition silicone impression material. Pour each impression twice using high strength dental stone. Use the first pour to fabricate the master casts for the sectioned dies and the second, a solid cast, for adjusting proximal contact points (Figs. 17-19). To make a facebow transfer, use the same three points of reference that were used for the initial facebow transfer at the diagnostic phase of the treatment. Make irreversible hydrocolloid impressions of the provisional restorations and pour them with stone. Use the casts of the provisional restorations to fabricate a custom anterior-guide table that will be used as an aid in the fabrication of the final restorations. In addition, make a centric relation record between the maxillary provisional restorations and the mandibular prepared posterior teeth at the restored occlusal vertical dimension to allow cross mounting of the casts of the provisional restorations with the master casts.21,22 Send the mounted master casts, the solid casts, and the mounted casts of the provisional restorations to the dental laboratory with a shade prescription.
Try-in the restorations in the mouth in the bisque-bake stage and adjust for the interproximal contacts, contour and occlusion (Figs. 20 & 21). The restorations were resent to the dental laboratory for glazing, and were received for cementation (Figs. 22-23). The intaglio surfaces of the restoration were microetched with a 50 aluminum oxide, and the restorations were cemented with a resin-modified glass-ionomer cement (Figs. 24-25). As with the provisional restorations, the patient was provided with a mutually protected articulation.
The importance of maintaining a high standard of oral hygiene was stressed to the patient. Toothbrushing and dental flossing techniques were reinforced and the patient was advised to use an over-the-counter 0.05% NaFl mouthrinse twice a day. The patient should return in 24 hrs for minor occlusal adjustments. Provide the patient with a heat-processed clear-acrylic-resin maxillary occlusal device with a mutually protected articulation occlusal scheme. This appliance should be worn during sleep and during the day as needed for protecting the restoration. Give the patient instructions on the wear and care of the occlusal device. Place the patient on 6-months’ periodic recall for prophylaxis and a six months’ prosthodontic recall (Figs. 26-28).
Choosing the adequate restorative materials for a full-mouth fixed rehabilitation is extremely important, especially in the case of the bruxing patient. In the case of the uncontrolled bruxing patient who needs a full-mouth fixed rehabilitation, the restorative dentist should consider the option of using metal-ceramic restorations with a metal substructure. The esthetics, the function, and the longevity of the future restorations are related to additional factors, such as the patient keeping periodic recalls and a maintenance regimen. Although new metal-free restorative systems provide superior esthetics, they must be used wisely. A thorough, clinical, radiographic, esthetic, and occlusal analyses, and a TMJ and masticatory muscles evaluations, must precede their use.OH
The author would like to thank Thompson Dental Studio in Ellisville, MS, for fabricating the restorations presented in this article.
Dr. Ariel J. Raigrodski is a diplomate of the American Board of Prosthodontics. He is Assistant Professor at the Department of Prosthodontics at Louisiana State University School of Dentistry.
Oral Health welcomes this original article.
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