Indications for dental implant treatment
Patients often present with a desire to replace missing teeth or are faced with the need to have teeth extracted for a variety of reasons (< ?xml:namespace prefix = "mbp" />Figures 16.1 and 16.2). Replacement of teeth with fixed implant restorations or the use of implants to support and retain removable dentures are evidence-based treatment options with the potential for very high success rates. Often, alveolar bone and soft tissue also require replacement, so implant treatment frequently involves replacement of alveolar tissues using both biological and prosthetic means.
Fig 16.1 Both of the central incisors have suffered irreparable damage as a result of trauma. Periradicular infection at the upper right central incisor is manifest as a fluctuant swelling on the buccal mucosa.
Fig 16.2 An edentulous patient with loose, uncomfortable dentures who wishes to discuss the possibility of using dental implants to improve the situation.
This chapter discusses indications for dental implants by considering the factors shown in Table 16.1.
Table 16.1 Indications for dental implant treatment
• Why does the patient wish to replace missing teeth?
• What are the prosthodontic advantages of implant treatment?
• What is the problem with an existing fixed restoration or the natural teeth?
• Is there a denture-related problem the patient wishes to solve?
• Does the cause of missing or failing teeth have any influence on indication for implants?
• Does the timing of tooth loss have any influence on indication for implants?
• What are the main drawbacks of implant treatment?
• Are there contraindications to implant treatment?
Why does the patient wish to replace missing teeth?
To improve aesthetics?
The wish to replace missing teeth is often understandably driven by a desire to smile with confidence and conform to socially accepted norms of appearance.
To improve masticatory function?
Because teeth perform keys roles in mastication of food, their absence often causes compromise in chewing function and may also indirectly affect nutritional status by influencing food choices.
To improve speech function?
The presence of teeth and alveolar structures is critical in production of certain speech sounds. Their absence can affect speech intelligibility (how an individual is able to communicate through speech).
To enable wind instrument playing?
Some wind instruments require anterior teeth to be present to enable the appropriate embrasure to be formed around the mouthpiece of the instrument.
To regain what has been lost?
Loss of a body part (e.g., a tooth) may be associated with a deep-seated desire to replace what is missing, irrespective of the role played by the anatomical part.
What are the prosthodontic advantages of implant treatment?
To avoid tooth preparation and possible sequelae
Removal of tooth structure, the inevitable exposure of cut tooth surface to bacteria in saliva, and other procedures involved in attaching bridge retainers to teeth are associated with a risk of pulp necrosis and the need for either extraction or endodontic treatment (Figures 16.3 and 16.4).
Fig 16.3 Developmental hypodontia treated with bridges utilizing full-coverage retainers necessitating removal of substantial amounts of tooth structure. The upper left central incisor carried a preexisting crown.
Fig 16.4 Developmental hypodontia treated with dental implants without the need to prepare intact teeth to attach bridge retainers.
No need for connectors between pontic and abutment teeth
Implants are ideally suited to restoring missing teeth where there are interdental spaces, particularly in the aesthetic zone (Figure 16.5).
Fig 16.5 This patient, who has a missing upper left central incisor that was replaced with a removable denture, wants to maintain the interdental spaces. A dental implant avoids the need for a connector, which would be difficult to hide from view, attaching a bridge pontic to abutment(s).
Avoids mechanical risks of conventional bridges
The longer the span of a fixed bridge, the higher the risk of mechanical complications such as superstructure fracture or decementation of a retainer. It follows that the longer the edentulous space, the more likely it is that implants are indicated as fixed tooth replacements.
The deep complete overbite—No need to accommodate a denture connector
When the mandibular incisors contact the palatal mucosa in the intercuspal position, it is difficult to provide a removable denture because the connection to the denture tooth will often produce an occlusal interference (Figure 16.6). A dental implant as the definitive replacement can circumvent this occlusal difficulty.
Fig 16.6 In occlusion, the deep complete overbite means that there is no space to accommodate a connector between a denture tooth and the major connector.
Concurrent use of an implant as an orthodontic anchor
Dental implants are well suited to use as orthodontic anchors because they do not move through the alveolus when subjected to low-level prolonged (orthodontic) forces. The prosthodontic advantage lies in the ability to use a provisional restoration on an implant as a guide to orthodontic alignment and ultimately to replace the provisional restoration with a definitive one (Figure 16.7).
Fig 16.7 Four premolars have been replaced with two implants carrying provisional restorations. The right premolar is being used as an orthodontic anchor. Both implant crowns act as guides to appropriate tooth positioning within the arch.
Linking implant restorations together
Linking natural teeth together for whatever reason is a concern because of the potential for differential tooth movement causing failure at the tooth–restoration interface that can be difficult both to diagnose and to manage. Because implants have negligible differential movement, linking them together is prosthodontically acceptable (Figure 16.8). A practical advantage of linking implant restorations together is that it reduces the number of interdental contacts that may require adjustment in order to achieve acc/>
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