Implant Treatment and the Edentulous Maxilla
Thomas J. Salinas, DDS
Patients with maxillary edentulism may seek care with dental implants as anchorage. A small survey of patient satisfaction indicates that both fixed and detachable treatment options do not significantly differ, aside from the cost.1 Diagnosing appropriate treatment for an edentulous maxillary arch can be a complex task that requires a systematic approach to achieve a predictable outcome.2 Many of these patients desire a fixed prosthetic reconstruction similar to existing fixed particl dentures and, as such, should be diagnosed properly to determine the feasibility of accomplishing this feat. In addition, a full-arch replacement indicates that at least eight osseointegrated implants should be placed. Depending on the underlying bone and opposing occlusal replacement, it may be necessary to add bone to the maxillary sinuses. Many of these cases will be restored to first molar position, which is marginally indicative for sinus augmentation. It is certainly possible to cantilever the occlusal table by one tooth if affordable anchorage has been accomplished by sufficient implant placement in the anterior region.
Steps for Aesthetic Considerations
As with any restorative case, the first step for aesthetic consideration is to analyze the smile frame of the lips and spatial relationship of the lips to the teeth (diagnostic waxup). The diagnostic waxup will provide a perspective on the restorative vertical dimension, lip support, and speech production. All these factors are critical for assessment of proper tooth position. Once these factors are assessed and determined to be favorable, a radiographic evaluation with a lateral cephalometric film and/or CT scan is appropriate with the diagnostic waxup in place.3 The lateral cephalometric film will illustrate the vertical position of the maxilla in relation to the occlusal plane. If this position places the alveolar ridge in a one-tooth proximity to the occlusal plane, a metal-ceramic or fixed restoration should be planned. A greater distance would suggest treatment with a removable prosthodontic restoration to facilitate development of sufficient space for the definitive prosthesis. The anterior position of the maxilla in relation to the cranial base will indicate whether the prosthesis should be incorporated into lip support.
An imaginary line connecting the superior portion of the external auditory meatus to the infraorbital rim is known as the Frankfort Horizontal Plane. An imaginary line drawn perpendicular to the Frankfort Horizontal and intersecting the junction of the nasal bone to the frontal bone is called the nasion perpendicular. The relationship of the nasion perpendicular to the greatest anterior concavity of the maxilla (point A), places the line within 3mm anterior or posterior to the concavity. The deviation of the concavity anterior or posterior to this line indicates the relative position of the maxilla.4 Since the position of the maxillary lip is supported in part by the incisal two thirds, a falanged prosthesis may or may not be necessary if the maxilla assumes an anterior position. The literature has indicated algorithms for treating edentulous maxilla with implants based upon space considerations, aesthetics, and speech. Speech production is based upon the incisal position of the maxillary anterior teeth. Labiodental sounds (eg, “F”, “V”) help the clinician to evaluate the anterior/posterior position of the teeth. Dentoalveolar consonants (eg, “T”, “D”, “S”) facilitate evaluation of the palatal contour of a restoration and allow the clinician to determine if a linguoalveolar seal is necessary. This decision may often indicate the need for a detachable restoration or a fixed reconstruction. Development of a provisional restoration attached to the implants may also facilitate proper speech assessment and evaluation of consonant pronunciation. This provisional restoration provides the clinician and the patient with an idea about the appearance of the final outcome, as it is literally a road map of the aesthetic, functional, and phonetic result.5
Final Evaluation of the Restoration
A final way to evaluate the design of the restoration is to make reference to the restorative space that exists on the articulator prior to fabrication. This evaluation process should include information on maxillary prominence, speech production, and aesthetic display. Fixed reconstructions are generally indicated in the treatment of a single-tooth restorative space dimension to provide an acceptable phonetic seal and a solid-state cemented or screw-retained metal-ceramic reconstruction. A detachable design can be used when additional space is available to allow placement of a substructure and a superstructure with horizontal locking attachments. It is the general consensus that the greater number of moving components, the greater the demand for servicing. Conversely, metal-ceramic failure is a difficult scenario to overcome while satisfying the stringent requirement of a pssive and simultaneous intimate framework fit. The patient should be counseled on the potential untoward effects of prosthesis servicing during the post-operative phase.
Treating patients who have an edentulous maxilla with osseointegrated fixtures requires a stringent protocol to achieve treatment goals. Hopefully, these cases can be identified before any surgical treatment is rendered to arrive at a predictable outcome.
*Assistant Professor, Department of Otolaryngology, University of Nebraska medical Center, Omaha, Nebraska.
- Zitzmann NU, Marinello CP. Treatment outcomes of fixed or removable implant-supported prostheses in the edentulous maxilla. Part II: Clinical findings. J Prosthet Dent 2000;83(4):434-442.
- Zitsmann NU, Marinello CP. Treatment plan for restoring the edentulous maxilla with implant-supported restorations: Removable overdenture versus fixed partial denture design. J Prosthet Dent 1999;82(2):188-196.
- Zitzmann NU, Marinello CP. Implant-supported removable overdentures in edentulous maxilla: Clinical and technical aspects. Int J Prothodont 1999;12(5):385-390.
- McNeill C. Science and Practice of Occlusion. Carol Stream, IL: Quintessence Publishing, 1997.
- Jimenez-Lopez V. Oral Rehabilitation with Implant-Supported Prostheses. Carol Stream, IL: Quintessence Publishing, 1999.