3 Pre-Operative Assessment and Prosthetic Planning: The Edentulous Patient
D. Wismeijer, P. Casentini, M. Chiapasco
The estimated percentage of denture wearers who are dissatisfied with their denture is between 10% and 30%, depending on the method used (van Waas, 1990; Kent and Johns, 1994). Their principal complaints are: loosening of the lower denture, pain during function, problems with speech, esthetics, and problems while eating.
Most of these complaints can be imputed to the loss of retention and stability of the lower denture. This in turn is primarily caused by resorption of the denture-bearing area. During the first 1 to 3 years after tooth extraction, bone resorption is at its strongest. The resorption process slows down after this initial period but never stops completely. In the long term, the mandible will still decline in height at an average rate of about 0.2 mm per year (Tall-gren, 1972). In some cases, the resorption is so severe that it is impossible to make a complete denture that satisfies the patient’s needs.
Before oral implantology came into its own, patients with severe denture problems were treated by preprosthetic surgery (vestibuloplasty, lowering the floor of the mouth, or ridge-augmentation procedures aimed at improving the morphology of the denture-bearing area) or with dentures fitted with soft linings. Often, these treatment options did not offer a permanent solution (Stoelinga and coworkers, 1986; Mercier and coworkers, 1992; van Waas and coworkers, 1992).
But during the past few decades, dental implants have been commonly employed in the treatment of edentulous patients with denture problems. Implants can be used to restore the edentulous jaw in different kinds of ways. If a sufficient number of implants can be placed and the vertical and horizontal relationships are favorable, a fixed implant-retained prosthesis can be delivered. This prosthesis can only be removed professionally.
A second option is a removable denture. Both options differ in their esthetic possibilities, limitations for dental hygiene, and not least their cost effectiveness. A removable overdenture is less expensive than a fixed prosthesis on dental implants and represents an attractive treatment option for a large number of patients.
Because of the many factors influencing the choices treatment providers have, it would seem logical to split the decision-making process into several steps:
The initial examination leading to a review of the treatment options and a preliminary treatment plan
The specific treatment plan based on the patient’s choice of treatment options
The proposed implant-prosthetic design
To begin with, the patient’s wishes and complaints, general health, and treatment history must be studied. An initial examination is carried out whose aim is to identify any relative or absolute contraindications for implant treatment. In this way we can see, at an early stage, whether the patient is a good candidate for oral implant treatment. The patient receives a broad outline of and general information on possible treatment options. Based on the patient’s wishes, a preliminary treatment plan is set up.
Following the preliminary treatment plan, specific information is gathered, looking at the possibilities of implant prosthetic constructions, and the patient is informed about the different treatment options and what may be expected from them.
A final treatment plan, including the number of implants, their size and form, their position in the jaw, and the type of superstructure, is then developed. The specific treatment steps, a corresponding time line, and the financial implications are decided on. Often this will be agreed on by the clinician and the patient in a signed informed consent. It is from here that the actual treatment takes its course.
The aspects that need to be addressed belong to different areas: patient motivation, general health, smoking habits, dental history, extraoral and intraoral examination, general radiological evaluation, indication, and preliminary treatment plan.
Patient perspective/motivation. Patients’ perception of implant treatment is not always objective; quite often they will have received their information about possible treatment options from the media or from other patients. Misinformation can be disastrous when treating implant patients. It is therefore important to identify the patient’s own wishes and esthetic demands. Often, patients have to be led to understand the difficulties and limitations associated with implant treatment. Patients must be aware that a certain degree of compromise may be required, and in some cases their expectations have to be adjusted to reality. Quality in dentistry can be defined as “satisfying the expectations the treatment provider has created for a patient.” It is therefore of utmost importance that the treatment provider has good insight into the patient’s expectations and can provide a treatment that meets the expected goals. Patients will be asked questions such as: “How long ago were your teeth extracted?” and “Why did you lose your teeth?” These questions give some insight into the treatment history and a patient’s attitude towards dental treatment. “How many dentures have you had since you lost your teeth?,” “How old is the last denture you had made?,” and “Are you wearing the last denture you had made?” deliver insights into the problems patients might have when wearing dentures. A patient who complains about a removable dental appliance and expects an FDP to work exactly like their natural dentition both esthetically and functionally is totally different from the patient who is looking for more retention for a removable denture.
From the patient’s perspective, a fixed restoration is sometimes preferred, especially by patients who have experienced an inadequate removable prosthesis and by patients with an excessive gagging reflex. There are also patients with a hopeless residual dentition who are candidates for total tooth extraction. They often choose to avoid this and may then ask for a fixed implant-supported rehabilitation.
Patients should also receive adequate information regarding the limitations of a fixed prosthesis, which is more demanding in terms of maintenance, sometimes causing phonetic problems, and is usually more expensive.
Moreover, patients must be informed about the final appearance of an implant-supported prosthesis and about how their smile will appear after rehabilitation. The clinician should be able to illustrate the most common types of rehabilitations using photos, videos, or graphics to highlight some of the benefits and limitations of the different treatment options.
A fixed prosthesis is usually more expensive than a removable denture, since implant components and laboratory materials often cost more. On the other hand, this is not a strict rule, as some types of removable implant-supported prostheses involve expensive materials and laboratory techniques.
A cost analysis is of course an important factor that influences the patient’s choice of the final type of prosthesis and must be discussed with the patient.
Finally, patients should be reassured that the scientific evidence clearly shows that both removable and fixed implant-supported rehabilitations of the edentulous jaw can significantly improve their quality of life (Wismeijer and coworkers, 1992, 1995, 1997; Feine and coworkers, 2002; Trulsson and coworkers, 2002).
General health/medical risks. The pretreatment evaluation should always include an analysis of the patient’s medical status. Absolute contraindications for implant treatment are rare, but several risk factors have been described in the literature. A higher risk of peri-implantitis has been demonstrated in patients who are affected by uncontrolled diabetes or immune diseases, bone diseases, who are undergoing treatment with oral bisphosphonates or radiation, who are immunocompromised, or who smoke (Ferreira and coworkers, 2006).
Etiology of the patient’s edentulism. The dental history of the patient is also of importance. The risks related to implant loss in patients who lost their teeth to caries or trauma are much lower than when patients lost their teeth to periodontal disease. If teeth were lost to periodontal disease, patients run a higher risk of developing peri-implant infection, even if they are completely edentulous (Karoussis and coworkers, 2004; Heitz-Mayfield, 2008).
Age. Age is sometimes seen by patients as a possible contraindication for implant treatment. The literature, however, gives no guidelines for an upper age limit when treating patients with oral implants. On the other hand, elderly patients often present general health problems that might eventually lead to contraindications for therapy. Implants are be indicated in young patients (patients that have not yet reached the end of their growth phase) (Bernard and coworkers, 2004; Fudalej and coworkers, 2007).
During the extraoral examination, special emphasis should be placed on the evaluation of the smile line and the amount of facial support. Especially in patients who have been edentulous for a longer period, a fixed implant-supported often does not yield the same esthetic results as a removable implant-retained prosthesis. Often, the morphology of the buccal crest of the alveolar ridge affords the upper lip inadequate support. In those cases, a fixed dental prosthesis might not give the expected esthetic result, as the implants will often be placed further posteriorly. The anterior teeth need to be positioned with a more anterior angulation, giving the upper lip at least some support and restoring the patient’s facial profile. A removable implant-retained overdenture can be extended labially more easily, allowing the restorative dentist to create a more natural esthetic result. A patient who exposes a large portion of the maxillary soft tissues while smiling must be considered an esthetic risk patient (Goodacre and coworkers, 2003).
Hygiene. Oral hygiene can easily be evaluated in patients who are edentulous in only one arch. The literature does not show a significant correlation between oral hygiene and implant success. When treating edentulous patients, especially those who have been edentulous for a long time, one should remember that they will often have forgotten how to perform oral hygiene appropriately. In some cases, it would seem prudent to develop a treatment plan based on simple solutions (such as an implant over-denture) instead of some more elaborate implant-based treatment. For patients with a handicap that impairs adequate oral hygiene, it is also often necessary to provide a treatment plan that favors simple solutions.
Periodontitis/history of periodontitis. Any treatment of periodontitis must always be carried out before implant treatment. The bacterial component of peri-implantitis seems to be the same as in periodontitis. The subgingival plaque in peri-implantitis infections consists of an anaerobe bacterial flora dominated by gram-negative bacteria. Bacteria such as Porphyromonas gingivalis, Tannerella forsythensis, and Spirochetes are common. In partially dentate patients, these pathogens most probably migrate from the subgingival area due to intraoral transmission (van Winkelhoff and coworkers, 2000). In patients who are edentulous in only one arch, periodontal conditions of the opposite arch should always be evaluated during the first visit.
Acute infection. The presence of acute infection is an absolute contraindication for oral implant treatment. These infections should be treated until healed before implants are inserted.
Jaw opening. When carrying out an intraoral examination, it is wise to register the jaw opening. A limited jaw opening often makes it impossible to carry out implant treatment in the posterior region.
One should also be careful with implant treatment in patients with a history of severe bruxism. These patients run the risk of overloading individual implants, so treatment plans involving FDPs must be based on vertical load on the implants. In these cases, an implant-retained overdenture may be the lesser risk. One advantage of a removable denture is that it is easier to repair than an FDP.
Interarch relationships. Discrepancies in interarch relationships, such as crossbites, extreme Angle class II or III jaw relationships, and an extremely reduced maxillo-mandibular space, can lead to biomechanical risks in the prosthetic phase. It is therefore important to recognize these potential problems at an early stage. Solutions to these problems may include:
Not inserting implants
Orthognathic surgery prior to implant placement
An alternative prosthetic treatment plan that avoids the anticipated complications (removable instead of fixed)
In the case of inadequate intermaxillary space, reducing the mandibular bone height, providing adequate space for the bar clip attachment or the fixed prosthesis, could be considered; an option might be an over-denture with single attachments
Morphology of the edentulous bone crest. Intraoral palpation should be used to evaluate the following: irregular bone structures, the sharpness of the edentulous alveolar ridge (knife-edge ridge), flabby ridges, muscle insertion and the floor of the mouth, mandibular tori, and the shape of the arch.
A knife-edge ridge often needs correction before inserting implants. A plateau must be created that is wide enough to insert implants with an adequate width. In some cases, this might mean that the alveolar ridge has to be reduced by 5 mm or more. Furthermore, irregular bony structures under the soft tissues in the denture-bearing area should also be corrected, as they will cause discomfort for the patient otherwise.
The depth of the vestibule should also be inspected. Bone resorption often results in a shallow vestibule. A removable implant-retained overdenture is more likely to provide substantial lip support in these cases, giving a more acceptable esthetic result.
Quality and quantity of the soft tissues. During the intraoral examination, it is also advisable to inspect the amount of keratinized mucosa. It should be noted that this factor is not related to the success of implant treatment, but that it plays a part in patient comfort. If the implants are not surrounded by a cuff of keratinized mucosa, patients not infrequently complain about discomfort around the implants. The soft tissues tend to stretch along the surface of the implants and the implant abutments, causing pain. Large and thick keratinized tissues can be a helpful factor in fixed rehabilitations because it facilitates soft-tissue management to recreate inter/>