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Women Dentist Journal
April 2006
Lee Ann Brady DMD
Single Tooth Implant Surgical Guide
Not many years ago, dental implants were new, fascinating, and experimental procedures that could restore patients to a higher level of function. Times are changing. It is becoming increasingly common in my practice for patients to already be familiar with dental implants. They ask me to help them understand what role implants might play in replacing missing teeth or allowing them to transition away from removable prosthetics.
As implant technology and surgical techniques advance, our criteria for success needs to advance as well. The days are gone when successful integration of a fixture measured success. We need to add obtaining optimal esthetics and functional results to our criteria for satisfaction. Obtaining naturally beautiful esthetics, optimal function, and predict- able long-term results starts with a comprehensive evaluation. I begin by getting to know my patients so I can understand how dental implants will help accomplish their goals for dental health. Then I discover the technical components of their dental conditions.
Dental breakdowns result when two factors become out of balance with a patient’s adaptive capabilities, bugs, and forces. Dental implants and teeth respond differently in the presence of these two factors. For each patient, achieving success begins with understanding present risk factors and their susceptibility to both. Optimal survival rates for dental implants occur when the fixtures are placed in environments free of inflammation and infection. As part of a comprehensive evaluation, I complete a thorough periodontal examination, including full-mouth sulcus depths, furcation involvements, attachment loss, mobility, tissue character, and home-care evaluation. The team’s goal is to assist patients in getting their mouths healthy and clean in a maintainable way, prior to implant placement and final restorative therapy.
Single Tooth Implant to replace Existing Bridge
In addition to peri-implantitis, research shows that failure of implants following successful integration can be linked to overload. To minimize this risk, we must understand and manage each patient’s occlusion. (I gain an understanding of how a patient’s mandible arc is in centric relation and the relationship of the upper and lower teeth as they contact in this arc, centric occlusion.) The presence of a first point of contact and slide from centric occlusion to the maximal intercuspal position represents a risk factor for potential occlusal overload. Managing this will become part of the final treatment considerations.
Final Restorations
As part of understanding the occlusal risk factors, I evaluate a patient’s functional occlusion, including the number and placement of contacts in MIP along with the existing anterior guidance. The presence of unbalanced occlusal contacts, muscle dis-coordination upon clenching, inadequate anterior guidance, and inadequate crossover guidance must be addressed to minimize the risk of occlusal overload. Parafunctional or dysfunctional activity pose increased risk of implant failure, so during the occlusal examination, I observe any signs or symptoms of occlusal disease such as wear, crazing, cracks, fractures, fremitus, and others. To complete the occlusal evaluation, I take impressions along with a facebow and bite registration to create a 3-D record of a patient’s existing occlusal relationships and functional patterns.
The stability of a patient’s occlusion depends in part on the stability of the temporomandibular joint, so I take a thorough history. The joints are palpated and a load test is completed to understand the relationship of the condyle disk assembly. The connection between the joints and the occlusion is mediated by the musculature, so a muscle exam with palpation and range-of-motion measurements is done. Positive response to muscle palpation means the system is overloaded and that time must be spent understanding the interrelationships more thoroughly prior to proceeding with definitive therapies.
Often, a patient and I need to gain insight into what he or she does with the teeth beyond normal function, or, as a means to verify centric relation, we progress into bite-splint therapy. A patient’s time with the bite splint is invaluable because it affords me the opportunity to evaluate the presence of occlusal habits and design an appropriate occlusion that will optimize forces along the long axis of teeth or implant fixtures and create anterior guidance. For some patients, the bite splint becomes part of our long-term plan to manage occlusal risk factors following restorative care.
Achieving an optimal esthetic result begins at the evaluation. I include a complete set of diagnostic digital photographs at every evaluation. I take several full-face and profile images to assess facial esthetics and their relationship to the appearance of the teeth. Close-up images allow the patient and me to discuss tooth display at rest and full smile, gingival discrepancies, gingival display, and smile appearance, in addition to shade and tooth position. When the restorative phase is complete, I want it to be difficult to discern natural teeth from the restorations. Of- ten, changes such as periodontal surgery or orthodontic repositioning must be made pre-restoratively.
Single Implant Placement
Implant dentistry has evolved beyond placing the fixtures where there is existing bone without regard for the restorative and esthetic consequences. Now, understanding the anatomy of the soft and hard tissues as they affect implant placement is part of the preliminary information that must be gathered. Digital photographs, in addition to their use in esthetic evaluation and planning, are invaluable tools for evaluating soft-tissue contours. This information, along with the clinical soft-tissue exam and the models, give me a complete picture of the soft-tissue parameters that affect the implant-placement outcome. I also need a clear picture of the hard-tissue anatomy, so during the past few years, I added CT imaging to the diagnostic data I collect for cases in which I contemplate implants. These images allow implant surgeons and me to have thorough understandings of the bony architecture and anatomical factors, such as maxillary sinus and inferior alveolar nerve position in areas where we plan to place fixtures. We can then incorporate site-augmentation procedures if needed to achieve optimal results.
Implant dentistry is most often accomplished using a team of dentists who work together to accomplish the restorative and surgical treatment. Part of planning for success means giving each member of the team (orthodontist, periodontist, implant surgeon) an opportunity to become familiar with patients’ conditions. Once this has been accomplished, team members discuss each case and how we can help one another accomplish the best results. The removal of teeth prior to implant placement is one of the many topics our team works out to optimize results. This can be critical in implant-site preservation and creation. The timing of this treatment and who will be responsible for extractions must not be overlooked.
Another tool our team uses to create optimal implant placement sites is orthodontic extrusion of hopeless teeth prior to their removal. Some- times this is in conjunction with other orthodontic therapies to align adjacent teeth, create space for implant fixtures, or correct gingival discrepancies. Or, it can be the reason for planned orthodontics. For treatment to proceed seamlessly, these issues and many others must be well coordinated by a team. Often, we invite patients to these planning sessions, or we come together following our planning sessions with patients to answer questions and present treatment.
The first objective is periodontal health and stable dentition. In con- junction with this, we verify centric relation and move toward an occlusal scheme in which the patient’s joints are seated with muscles relaxed, and when they close, all teeth touch simultaneously. When force is applied, neither the jaw nor any tooth deflects. With teeth in contact, if the patient moves his or her lower jaw right, left, forward, or backward, no posterior tooth touches before, harder than, or after any anterior tooth.
CT Guided Implant Placement
The final piece of the diagnostic puzzle is the restorative work-up. The final prosthetic result is worked up on a set of mounted models, including soft- and hard-tissue augmentation, final tooth placement based on esthetic and functional parameters, and refinement of the occlusion. This work-up then can be used to create surgical guides for site-augmentation surgery that is planned as a separate procedure from final implant placement. A copy of the proposed prosthetic result is fabricated and impregnated or coated with a radiopaque material so that the patient may have a CT image taken with the prosthetic mock-up in place. This image is then used to finalize planning for the implant placement and any necessary site-augmentation procedures not yet accomplished. The image is exported into a software program. Fixture placement is planned so that the abutments are contained within the restorative framework without compromising embrasure spaces or forcing the restorative too far to the buccal or lingual, while being able to see the bony architecture and choose the optimal fixture sites at the same time. We choose the implant length and diameters based on existing anatomy or augment the site to use the fixture of our choice. The image also allows us to analyze the crown-to-fixture ratio of the final result based on existing ridge, or optimize the long-term outcome by grafting the site and reducing this ratio.
This final piece is crucial in planning the timing and sequencing of surgical treatment, as well as making sure that the fixture placement supports the optimal restorative outcome. Understand the patient’s present condition, manage any risk factors, and thoroughly plan. These allow us to achieve the patient’s desired functional and esthetic results with predictable long-term success.
