“Restorative Leadership” in the Digital Era of Implantology
George A. Mandelaris, DDS, MS
Some 30 years ago, it was enough that implants were immobile, painless, and had minimal (< 0.2 mm) annual bone loss and a 10-year survival rate of 80%.1 Today, however, few practitioners would be satisfied with such tenets of success, as technological advances have boosted survival rates to consistently exceed 95% over 5 to 10 years.2-5 An esthetic and functional final restoration—not just implant survival—is now the goal of most implant therapy.
The incorporation of 3-dimensional (3D) imaging into implant dentistry has been a major driver in the rapidity of its advancement. Cone-beam computed tomography (CBCT) imaging enables the identification and evaluation of key anatomic structures such as the inferior alveolar nerve or maxillary sinus.6-8 It allows clinicians to analyze alveolar ridges before implant placement or augmentation and evaluate hopeless teeth to determine if they may be candidates for immediate implant placement.9,10 CBCT imaging increases the amount of available information exponentially. However, all the information obtainable through imaging is relatively meaningless without “restorative leadership.”
A prosthetically driven treatment modality, contemporary implant therapy requires a combination of 3D imaging within a team context guided by the restorative goals. The role of surgical therapy is to support these objectives. The concept of “collaborative accountability” helps implant providers ensure consistent results.11 Considerations in each case include the shape and contour of the teeth, their emergence from the gingiva, and the volume and appearance of the soft tissue. These evaluations should be incorporated into the CBCT imaging to maximize the 3D information and allow for meaningful treatment planning. A personalized diagnostic and treatment pathway developed for the patient helps optimize interdisciplinary communication.
The scope of the diagnostic and treatment-planning process depends on the complexity of the case. Mecall12 proposed five “case types,” each requiring varying levels of diagnostic workup and treatment planning.
Case Type 1
These are the least complicated cases, because both the dental and surgical anatomies are within normal limits. Replacement of a tooth (or teeth) can be completed without modifying the surrounding architecture. Thus, a diagnostic wax-up for these cases involves the missing tooth or teeth alone. The information from this wax-up can then be transferred to the patient’s 3D planning through either the fabrication of a scanning appliance or optical imaging of the diagnostic wax-up and merging it into the 3D plan.
Description: Acceptable tooth position; favorable gingival symmetry, volume, and color; normal bone height and width; and occlusal stability.
Treatment option: Dental implant and restoration.
Case Type 2
In these types of cases, the dental anatomy is within normal limits, but minor adjustments to the surgical anatomy are needed. If early loss of the facial bone is evident, the ideal wax-up needs to be fully contoured (replace both teeth and soft tissue). Conversely, if the phenotype is thin/discolored but spacially correct, a tooth-form wax-up may suffice. This information is then used to complete the patient’s 3D planning.
Description: Gingival asymmetry or color alteration, evidence of slight facial bone loss, possible mucogingival abnormalities or a thin periodontal phenotype, and possible local occlusal instability.
Treatment options: Orthodontic movement of teeth, soft-tissue grafting, and dental implant and restoration.
Case Type 3
These cases present with surgical anatomy that requires alteration while the dental anatomy remains mostly within normal limits. Horizontal ridge augmentation and/or soft-tissue augmentation is often needed to correct the anatomic limitations, and, therefore, a fully contoured wax-up is required. After transferring this wax-up to the 3D image, the providers are better able to identify the most appropriate surgical and prosthetic treatment modalities.
Description: Predominantly horizontal with some vertical bone loss, altered occlusal vertical dimension (OVD), loss of mesiodistal space within arch, and possible occlusal instability.
Treatment options: Orthodontic movement of teeth, hard-tissue augmentation, soft-tissue grafting, crown lengthening, and dental implant with traditional or cantilevered restoration.
Case Type 4
Type 4 cases, which are relatively complex, involve modification of both the dental and surgical anatomies. These cases may present with a combination of vertical and horizontal bone loss with supraeruption, altered OVD, or inappropriate space for ideal tooth form. They often require some vertical augmentation of the residual ridge in addition to the horizontal augmentation. As such, they require at least a fully contoured diagnostic wax-up but may benefit from a trial tooth setup if the discrepancy between actual and ideal anatomy exists in both arches.
Description: Primarily vertical with some horizontal bone loss, altered OVD, loss of mesiodistal space within arch, and possible occlusal instability.
Treatment options: Orthodontic movement of teeth, hard-tissue augmentation, soft-tissue grafting, crown lengthening, and dental implants supporting hybrid prosthesis, overdenture, or partial denture.
Case Type 5
Patients with significant dental and anatomic shortcomings are considered case type 5 (eg, an atrophic, completely edentulous ridge). These patients lack adequate tooth support to determine OVD, necessitating the fabrication of a trial tooth set-up. If the patient has an existing and well-fitting denture, the current prosthesis may either be duplicated into a differential barium gradient (30:10) scanning appliance or, more commonly, used as part of a dual-scan imaging technique.
Description: Significant vertical and horizontal bone loss, loss of perioral musculature support, and occlusal instability.
Treatment options: Bone graft, soft-tissue grafting, and/or dental implants supporting hybrid prosthesis or overdenture.
Transferring Data From the Lab to the Scan
Traditionally, to transfer an ideal wax-up into 3D data, a scanning appliance would be fabricated, which the patient would wear while the CBCT image is captured. This appliance typically is fabricated from radiopaque material so it can be visualized radiographically to enable case planning.
More recently, 3D technology has evolved to allow the transfer of data from the wax-up without the use of a scanning appliance. With this technology, a CBCT image of the patient is first made without a scanning appliance in place. Then, a wax-up is duplicated into a stone cast, the cast is optically scanned, and this data can be merged with the original CBCT scan of the patient using planning software. Patients who already have a well-fitting prosthesis can be scanned with the prosthesis in place in accordance with the dual-scan protocol. The prosthesis is then scanned alone, and the two images are merged using fiduciary markers attached to the prosthesis that allow for proper 3D alignment.
While 3D imaging has drastically increased the capability to evaluate head and neck anatomy, plan cases, and identify favorable sites for implant placement, its utility still requires “restorative leadership” for it to meet its full potential. Integration of digital technology, including implant planning software, is an emerging standard of care but is not a substitute for sound prosthetic fundamentals or biologic principles of wound healing. It is the restorative dentist who must define and communicate the expected outcomes to the interdisciplinary team. There is no one-size-fits-all approach to achieving ideal implant esthetics and function; however, organizing patients into case-type patterns helps guide clinicians through the diagnostic phase of implant care and maximizes the potential benefits of CBCT imaging.
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About the Author
George A. Mandelaris, DDS, MS
Adjunct Clinical Assistant Professor
University of Illinois, College of Dentistry
Department of Gradtuate Periodontics
Chicago, Illinois; Private Practice
Park Ridge/Oakbrook Terrace