J. Bryan McLaughlin DMD, MPH CPT, DC
ALL CLINICAL CASES
The integration of classic prosthodontic principles and techniques with new technology offers the potential to improve on time-tested methods. Meyer1 first described the functionally generated path technique for complete dentures almost 60 years ago, and yet it’s utilization today to achieve stable bilateral balanced occlusion is rare. Part of this is likely due to its complexity. His technique involved a process of recording cuspal pathways during functional movemenets, pouring a stone core into that recording, mounting the core, and then selectively grinding the opposing denture teeth. Vig2 later modified this technique slightly, using a record base with an acrylic fin that contacted the opposing teeth’s central grooves, staying in contact with those teeth during excursive movements, and acted as a support for the material that would record the functional movements. This article will present a simplified functionally generated path technique that is performed indirectly, and results in an occlusion fabricated using pressed lithium disilicate.
A 57 year-old edentulous male presented to the prosthodontic clinic to be evaluated for a maxillary complete denture and mandibular four implant overdenture (Fig 1a-b). Maxillary and mandibular complete dentures were fabricated using CAD/CAM record bases (Avadent, Global Dental Science).3 Locator housings were picked up in the mandibular denture, and CADIAX clutches (Whip Mix) were attached to the record bases with Blue Mousse (Parkell Inc). Mandibular movement was then recorded on the patient to accurately program the articulator.
Technique
- Fabricate complete dentures using preferred method.
- Ensure complete dentures are mounted in centric relation on an articulator with settings accurately programmed.
- Reduce the occlusal surface of the mandibular posterior teeth, placing a retention groove within the central area of the teeth (Fig 2). It may be advisable to lower the buccal margin to prevent the need to perfectly match the ceramic shade being used to the shade of the denture teeth.
- Apply Petroleum jelly (Vaseline) to the surface of the prepared teeth, as well as the occlusal surface of the opposing teeth.
- With the dentures on the articulator, apply pattern resin (GC America) to the prepared mandibular teeth using a brush bead technique and close the maxillary teeth into the pattern resin. Open and close the articulator repeatedly to prevent the pattern resin from sticking to the maxillary teeth. This should produce in the pattern resin an impression of the occlusion of the maxillary teeth (Fig 3).
- After the pattern resin has completely polymerized, reduce the resin leaving a fin that corresponds to the central groove and marginal ridges of the opposing teeth (Fig 4). This is the sulci ridge.
- Move the articulator through excursive and protrusive movements. Adjust the sulci ridges so that they maintain contact with all the opposing teeth through these movements. Adjustments to the maxillary denture teeth may need to be made to achieve smooth, simultaneous contact.
- Warm baseplate wax (TruWax, Dentsply Trubyte) and apply to the pattern resin on either side of the sulci ridge and move the articulator through excursive and protrusive movements. This will produce flat surfaces for the functional areas. Wax can be added to non-functional areas and refined to look like normal tooth morphology (Fig 5).
- Marginate with margin wax (Company?).
- Remove patterns from denture (Fig 6), sprue, invest (Company?), burn out wax, press with Emax press (Ivoclar) in a shade to match denture teeth, recover from investment, and polish (Fig 7). High translucency ingots will most closely match premium denture teeth.
- Prepare tooth surface for bonding by rubbing choloroform onto surface. If chloroform is not available use monomer. Prepare intaglio surface of onlay with etch and silane. Cement onlays in place with dual cure resin cement (Nexus NX3, Kerr). It is preferable to use a clear cement to avoid a visible line.
- Place dentures on articulator and refine occlusion.
- Deliver dentures. Check patient function and refine occlusion (Fig 8a-c).
Summary
This method greatly simplifies that described by Meyer. It is less technique sensitive and may allow more clinicians to comfortably treat patients with a functionally generated path occlusion, providing the stability that bilateral balance allows. It is very important that clinicians take good records, as inaccuracy in the records will directly translate to occlusal inaccuracies at final delivery. In this case a CADIAX recording was obtained to program a semi-adjustable articulator. A fully adjustable articulator would have been more ideal so that factors that may have an effect on ridge and groove direction, such as intercondylar distance, could be more precisely controlled. At the very least, it is recommended that the casts be mounted on a semi-adjustable articulator using a facebow. The mandibular teeth were chosen to receive the FGP onlays due to the role of the maxillary teeth in establishing ideal esthetics. It may be more difficult to perfectly match the ceramic onlay to the denture teeth in the maxilla and remain unnoticed than in the mandible.
References
- Meyer FS. The generated path technique in reconstruction dentistry: Part I: Complete dentures. J Prosthet Dent. 1959:9(3); 354-366.
- Vig RG. A modified chew-in and functional impression technique. J Prosthet Dent. 1964:14(2); 214-220.
- McLaughlin JB, Ramos V Jr. Complete denture fabrication with CAD/CAM record bases. J Prosthet Dent. 2015 Oct;114(4)493-7.
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