Maxillary Esthetics, Mandibular Function: A Rationale for Predictable Treatment of the Moderately Worn Dentition
An older patient presented with concerns about tooth wear. A treatment plan driven by the dominant risk factors of esthetics and function was preceded by a comprehensive evaluation to determine the etiology of the moderately worn dentition. Treatment goals included lengthening maxillary teeth, leveling the posterior occlusal planes, opening the vertical dimension of occlusion, and establishing bilateral simultaneous posterior occlusion. Esthetic parameters were established with the maxillary arch, enabling the functional goals to be addressed with treatment in the mandibular arch.
When a motivated patient presents with a moderately worn dentition, the restorative dentist may be inundated with many questions that require answers. Examples include: What is the etiology of the wear? Is it active or has the patient adapted to the dentition? What is the prognosis for the remaining teeth? What role has parafunction played? What should be the endpoint of treatment?
In the absence of a system for diagnosis and treatment, information crucial to the predictability and longevity of the definitive restorations can be easily missed.1 A comprehensive evaluation will allow for the building of an individualized risk profile so that a treatment plan can be developed to address the areas of most significant risk without increasing risk elsewhere.2
Clinical Case Overview
A 59-year-old woman presented with concerns primarily about tooth wear, saying “I’m grinding my teeth down to nothing.” Her medical history was noncontributory, with hypercholesterolemia controlled with medication. However, she reported a history of joint pain, which subsided when she clenched her teeth. The patient’s dental history included 3 years of orthodontic treatment beginning at age 27, and previous treatment for periodontal disease, recession, and an unpleasant taste in her mouth when ill. Additionally, she reported a history of broken teeth, pits in the occlusal surfaces of her teeth, and having food become trapped between her teeth.
The patient wore a nightguard, but desired an appliance to wear both day and night. While changes in her dentition over the past 5 years provided the motivation for treatment, she had been disappointed with the esthetics of previous dental work, and, therefore, at this time also wished to modify the color of her teeth and change the length of her front teeth (Figure 1 through Figure 4).
Diagnostic Findings, Risk Assessment, and Prognosis
Periodontal: All probing depths were less than 3 mm, with no radiographic horizontal bone loss greater than 3 mm.
Biomechanical: No clinical caries were detected; however, additional risk factors of a high biofilm challenge reading at 2605 (CariScreen Meter, www.CariFree.com) and a habit of frequent eating were present.3 The clinical examination revealed multiple teeth with moderate erosion in both arches. All existing restorations had a questionable prognosis, potentially from an occlusal etiology. Teeth with full-coverage restorations were structurally compromised.
Functional: All teeth had evidence of moderate attrition from normal forces. Joint sounds were detected bilaterally, but all other findings were within normal limits. The patient currently wore a nightguard and requested a new one due to her concern about the loss of tooth structure. However, a diagnosis of parafunction was ruled out based on the absence of horizontal notches in her nightguard and the negative responses in the functional section of the dental history. The patient was diagnosed with occlusal dysfunction.
Dentofacial: The maxillary and mandibular teeth required modification due to diastemas, rotations, and inappropriate length. The patient’s lip mobility was low, the horizontal symmetry was acceptable, and the scallop was normal for the maxillary and mandibular teeth. The patient’s chief esthetic concerns were the loss of tooth length and the color of her teeth. Since the amount of tooth and tissue display determines the risk,2 and this patient had no tissue when smiling, the dentofacial risk was assessed to be low, with a good prognosis.
The treatment goals included the following:
• Level the posterior occlusal planes.
• Open the vertical dimension of occlusion (VDO) to allow leveling of the planes and provide adequate room for restorative materials.
Establish bilateral simultaneous posterior occlusion.
Initially, a Kois deprogrammer would be used to establish the mandibular treatment position of adapted centric relation. A wax-up at this position using the Kois Dentofacial Analyzer (www.koiscenter.com) was fabricated; this established the maxillary esthetic parameters, the posterior occlusal design, and the estimated final VDO.
The teeth would then be prepared for IPS e.max® (Ivoclar Vivadent, www.ivoclarvivadent.us) restorations, a posterior porcelain-fused-to-metal (PFM) fixed partial denture, and provisionalized using the wax-up as a guide. After delivery of the definitive maxillary restorations, a new deprogrammer would be fabricated and delivered.
An occlusion record could then be made and the definitive mandibular restorations fabricated. At try-in of the mandibular restorations, the patient’s occlusion would be equilibrated with the deprogrammer as a guide.
Records were made for the fabrication of the Kois deprogrammer. After the patient was fully deprogrammed, upper and lower casts and a bite record were made for the diagnostic wax-up fabrication.4
The Kois Dentofacial Analyzer system was used to communicate the patient’s esthetic (ie, maxillary) occlusal plane as well as the inclination of the midline and the maxillary tooth position to the dental laboratory. The casts were duplicated in the dental laboratory and both sets were articulated. Using a series of diagnostic photographs, a wax-up was fabricated to establish the appropriate lengths and positions of the final restorations, creating a blueprint for treatment (Figure 7 and Figure 8).
Step 1 in the Kois 10-Step Management tool is establishing incisal edge position. After the mounting platform had been adjusted vertically on the articulator to reflect the desired final tooth length and maxillary occlusal plane, the maxillary anterior teeth were waxed. As per Step 2, the maxillary posterior teeth were then waxed to the platform to level the occlusal plane. At this point, the esthetic parameters of the maxillary teeth were established, including the length and horizontal position of the teeth, the position and inclination of the midline, and the relative proportions of the teeth.
The lower model was then placed on the articulator. The final adjustment to the vertical dimension was determined by evaluating the length of the mandibular anterior teeth (Step 3) and the posterior occlusion (Step 4). The pin on the articulator was set to a vertical dimension that provided room to keep the mandibular anterior teeth at the predetermined length and level the posterior plane of occlusion.5 While not necessary for this patient, modification of the maxillary wax-up may be required to balance compromises between the maxillary and mandibular occlusal planes and the esthetic needs of the case. The posterior teeth were then waxed to achieve bilateral simultaneous contact, the treatment goal for occlusal stability.
The treating clinician and dental laboratory determined that the most predictable treatment sequence would be to treat the maxillary arch first to establish the esthetic parameters. After seating the maxillary restorations, the lower arch could be restored to establish the vertical dimension and bilateral simultaneous occlusion, thus satisfying the functional parameters.
A matrix of the wax-up was used to create a template of the final result in the patient’s mouth.6 This provided an opportunity for the patient to visualize the endpoint of the treatment and generated a guide for tooth preparation. The teeth were prepared with depth cuts through the matrix, so tooth structure removal was kept to the minimum required for the final restorations and not determined by current tooth position.
The maxillary teeth were then prepared for IPS e.max restorations. The preparations were designed to minimize the biomechanical risk to the teeth, provide adequate retention and resistance form, and allow sufficient space to satisfy the esthetic parameters of the restorative material.
The final impression of the maxillary preparations was made at this time using the dual-cord technique and a polyether impression material.7 Bite records were made of the upper preparations to the mandibular teeth to articulate the casts. Luxatemp® provisionals (DMG America, www.dmg-america.com) were fabricated directly using the matrix fabricated from the wax-up. After final adjustment of the provisional restorations, a model and facebow record of the provisionalized maxillary arch was sent to the laboratory to communicate in 3 dimensions the esthetic outcomes desired. One week later, the mandibular teeth were prepared, an impression was made, and provisional restorations were fabricated. However, final restorations were not prescribed for the mandibular teeth at this time.
Final maxillary restorations were returned for delivery. The fit surfaces were etched with 9% hydrofluoric (HF) acid and silanated in preparation for try-in and final cementation. Under local anesthesia, the fit and esthetics were verified and accepted by the patient before final cementation. The restorations were cemented with RelyX™ Unicem (3M ESPE, www.3MESPE.com), and occlusion was verified against the mandibular provisional restorations.
A study cast of the new maxillary restorations was made for the fabrication of a new Kois deprogrammer. The patient was instructed to return a week later for the final occlusal records of the maxillary restorations against the lower prepared teeth.
After fabrication of the definitive mandibular restorations, the fit, contacts, and esthetics were verified. After minor adjustment, the restorations were cemented with RelyX Unicem (Figure 9). The occlusion was adjusted to establish bilateral simultaneous posterior contacts using the Kois deprogrammer. The chewing envelope of function was refined with the patient simulating chewing on 22-micron articulating tape (Figure 10 through Figure 15).
Upon completion of the definitive restorations and final equilibration, the patient was advised to follow a 6-month re-care regimen due to her periodontal health and caries risk assessment. She was given a flat-plane occlusal splint to wear at night to protect her investment, although no signs or symptoms of parafunctional activity were present.
A thorough comprehensive examination was completed, and a diagnostic risk profile was developed for this patient, who presented with a moderately worn dentition. A treatment plan was established to return her to dental health. By establishing the esthetic parameters with the maxillary arch, the patient’s functional goals were finalized with the completion of treatment in the mandibular arch.
The authors would like to acknowledge the role of Dr. John Kois in realizing and sharing his risk-based treatment philosophy for the benefit of dental professionals and patients worldwide. They would also like to thank the staffs at Prosthodontics and Implants Northwest, Puyallup, Washington, and Protea Dental Studio, Redmond, Washington, for their hard work and dedication to changing people’s lives.
ABOUT THE AUTHORS
Leon Hermanides, CDT, NHD Dent Tech
Owner, Protea Dental Studio, Inc., Redmond, Washington; Clinical Instructor, Kois Center, Seattle, Washington
Kim Larson, DDS
Private Practice, Puyallup, Washington; Clinical Instructor, Kois Center, Seattle, Washington
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