March 2010, Volume 31, Issue 2
Published by AEGIS Communications
Joint-Based Dentistry: Full-Mouth Rehabilitation Based on Disc Placement
Robert G. Ritter, DMD, PA
Private Practice, Jupiter, Florida
Age at Initial Presentation: 57
Initial Presentation: January 5, 2006
Active Treatment Completed: March 22, 2006
On presentation, the patient had a reduced lower third facial height, 100% vertical overbite, and bilateral posterior crossbite. She noted discomfort of her left temporomandibular joint (TMJ) pre-auricular area. A magnetic resonance image (MRI) was taken of the TMJs. The patient was told she was off her left disc and her bite would continue to drift with time. She was given the option of orthodontics to change the vertical dimension and relieve posterior crossbites. The patient chose full-mouth rehabilitation to remove the crossbites and deep overbite, and she wanted a shade to match her final restorations. She had 28 units of single-unit pressed-over-zirconia cores.
The only significant finding was that patient was taking Synthroid. She had no allergies or heart or blood disorders.
Temporomandibular Joints: MRIs of both TMJs were taken. The Piper Classification was used in the diagnostic process. On the right side, there was a 12 o’clock disc in the closed position and on the disc in the open position. The patient was off the disc in a 9 o’clock position on her left side, and there was no recapture of the disc in the open position. The Piper Classification was Stage II on the right side and Stage IVb on the left (Figure 1 and Figure 2).
Extraoral: The patient exhibited no signs of collapsed bite or atrophy and had a decreased lower one-third facial height (Figure 3).
Intraoral: She had a deep 100% overbite and posterior bilateral crossbite (Figure 4). Her 15-year-old veneers were structurally intact, with no chipping or microleakage. The patient had discomfort in the pre-auricular area that had started 2 to 3 years earlier. She experienced soreness that radiated down the left side of her mandible. She also had a history of clicking in the left ear that had begun more than 5 years ago but had dissipated. Her maximum intercuspation position (MIP) was thought to have changed in the last few years.
The patient had lower anterior wear, and the maxillary had concavities on the lingual surfaces. During the examination, no posterior wear, abfractions, areas of bone loss, caries, defective restorations, abscesses, cysts, or lesions were observed (Figure 5).
Periodontal: Green (low)
Biomechanical: Red (high)
Functional: Yellow (medium)
Medical: Green (low)
Dentofacial: Green (low)
Periodontal: Green (low)
Biomechanical: Red (high)
Functional: Yellow (medium)
The short-term prognosis of the existing restorations and dentition was acceptable. However, as the incisal wear continued because of the restricted chewing envelope and with the TMJ discomfort, the long-term stability was in question. The prognosis included more TMJ issues and a loss of posterior bilateral simultaneous contacts.
Due to the patient’s history of disc displacement, continual observation and possible bite adjustments would be required long-term.
1. Reduce or eliminate TMJ pain.
2. Establish a more favorable amount of vertical overlap (100% at the onset).
3. Correct appearance of supererupted mandibular anteriors (correct curve of Spee).
4. Improve buccal corridor.
5. Establish simultaneous bilateral posterior contacts.
6. Stop the incisal edge wear on the linguals of the uppers and incisal edge of the lowers.
7. Provide a brighter smile.
2. Kois Deprogrammer
3. Records of upper and lower casts
4. Mounting and verification of constriction
5. Assessment of joint risk
7. Preparatory and impression
8. Laboratory fabrication of ceramics
9. Seat and check bite
Phase I: Deprogrammers
Fabrication of two Kois Deprogrammers, one of which was used to record a starting position and was transferred to the mounted models. The goal was to record the starting incisal edge position relative to the lower incisal edge (the overbite was 5 mm). The patient wore the deprogrammer for 4 weeks (Figure 7). Then, a new bite registration was taken. A bite was taken in both the sitting upright position and with the patient reclined in the operatory chair. The disparate bite registrations were consistent with a restricted chewing envelope. The maxillary casts were mounted with the new bite registrations, and the overbite was compared with the original mounting. The overbite was reduced by 1 mm. This indicated the mandible had moved forward 1 mm from the starting position. The Kois Deprogrammer also provided the ideal opening position. A diagnostic full-mouth wax-up was fabricated and included upper and lower pre-operative models, polyvinyl siloxane (PVS) matrixes, and facial and lingual reduction guides (Figure 8). At the initial preparatory appointment, all upper teeth were prepared and temped. Final impressions were taken, a Kois Dento-Facial Analyzer System (Panadent, http://www.panadent.com) was used, segmental bite registrations were done, and final pictures were taken (Figure 9). The lower teeth were overlaid with bis-acryl in the new vertical dimension so that the patient would adapt to the new vertical.
Phase II: Restorative—Maxillary
One week later the patient visited the author’s office for a discussion of the final shade and to determine her opinions regarding the shape and feel of her new smile (Figure 10). A few minor changes were accomplished, and impressions of the approved provisionals were taken and sent to the laboratory for reference. The restorations were fabricated in Noritake (Noritake Dental Ceramic, http://www.noritake-dental.co.jp) pressed to Lava™ zirconia (3M ESPE, http://www.3MESPE.com), and the temporary model was used to fabricate the final shapes. The restorations were returned, the provisionals removed, and the final restorations tried-in for fit and contacts. The internal aspects were treated with zirconia primer (Ivoclar Vivadent, http://www.ivoclarvivadent.com) and the porcelain butt margin was treated with Interface (Apex Dental Materials, http://www.apexdentalmaterials.com). The teeth were scrubbed with Consepsis primers for 15 secs per tooth and air dried. RelyX™ Unicem translucent shade (3M ESPE) was chosen as the cement. The restorations were spot-tacked, and the cement was removed by scalers and curettes. Any occlusal adjustments were made to the lower overlaid provisionals.
Phase III: Restorative—Mandibular
The patient returned the following week, and the lower teeth were prepared in a segmental fashion to preserve the vertical dimension established in the provisional phase. A segmental bite was taken with MegaBite (Discus Dental, http://www.discusdental.com). The teeth impressions were taken, and new provisionals were fabricated with Luxatemp® (DMG America, http://www.DMG.com). They were cemented with Systemp Link (Ivoclar Vivadent). The laboratory fabricated the final restorations from the same material and shades as the maxillary arch. The final crowns were seated similarly to the upper restorations (Figure 11 and Figure 12). The patient was then sat upright in the chair, and the functional analysis of the patient’s speaking and chewing patterns were recorded with 200-µm horseshoe articulating paper (Bausch Articulating Papers, http://www.bauschdental.com) (Figure 13). Any aberrant lines were removed, and this was performed as many times as needed to remove any lines that could cause friction and thus eventual chipping of porcelain. The last step was to use 8-µm shim stock to pull through the anterior four incisors to create room for freedom of movement (Figure 14).
The patient initially wanted to redo her dentistry because of the color of her restorations. After a complete examination with concurrent MRIs of her TMJs, she was fully informed of the structural damage that had already occurred and the need for follow-up bite adjustments that could continue for years after reconstruction. The patient had a history of continual soreness on her left side. At one time, she had an audible click that subsided without professional intervention. The patient had a lateral pole displacement that eventually led to a medial pole displacement and completely torn disc on her left side. She adapted to this change with consequences of discomfort, soreness, and a drifting MIP. The author was able to eliminate the posterior crossbite and deep overbite, as well as establish a new vertical dimension of occlusion (VDO) that provided a reproducible MIP. The patient became more comfortable in the established VDO and thus could function, chew, and speak confidently. The author provided the patient with all-ceramic dentistry that satisfied her desires for better esthetics, as well as provide strength for the definitive restorations (Figure 15 and Figure 16).