Case• 43. Bridge design
A 28-year-old woman presents to you in your general dental practice with an edentulous premolar space on the upper left. She would like this space filled. What are the options?
Her complaint is the appearance of the gap. She would like it filled in time for her wedding in a few months time and requests a bridge.
History of complaint
The patient had all four first premolars extracted for orthodontic treatment in her early teens. After treatment with fixed appliances the premolar space was closed and the result had been stable. However, she then lost the upper left second premolar because of a combination of caries and root fracture following root canal treatment. This was about 2 years ago and she has had no replacement since.
The patient first came to your practice 18 months ago, shortly after having had the second premolar extracted. You have made her dentally fit and instituted preventive treatment which appears to have been successful. No caries is present in any teeth and the gingival condition is good. The patient consumes a low sugar diet and has good oral hygiene.
The patient is fit and well with no medical problems.
No abnormalities are present on extraoral examination. The premolar space is visible during speech.
The patient has an almost complete and well restored dentition with small- or medium-sized amalgam restorations. Although two premolars are missing, the gap is only a single premolar-sized unit of space because of the orthodontic treatment. This is her only missing tooth.
There is a mesio-occlusal restoration in the upper left first molar tooth. The first molar and the incisor teeth are in class I occlusion, with canine guidance in left lateral excursion. The orthodontic treatment has left the canine and molar vertically aligned and there has been no significant mesial drift of the first molar in the 2 years since extraction. The features are shown in Figure 43.1.
▪ What alternatives are there for replacing the missing tooth and what are their relative advantages and disadvantages?
The options are shown in Table 43.1.
|Removable partial denture||Removable for cleaning; cheaper than a fixed replacement; flange useful to improve appearance if significant bone loss has developed buccally; appearance can be good.||Patients rarely prefer a removable prosthesis and dislike palatal coverage. If poorly cleaned it will compromise the gingival margin around several teeth. Retention may deteriorate with time.|
|Minimal preparation bridge||Appearance can be excellent. No coverage of the palate required. Conservative of tooth tissue. Subsequent preparation for a conventional bridge is possible.||More expensive, significant laboratory fees. Not suitable if there is significant loss of alveolar ridge after the extraction. Must be cleaned in place. Average lifespan of restoration only about 5 years.|
|Conventional bridge||As for the minimal preparation bridge. Additionally, crowning adjacent teeth allows their appearance to be improved if heavily restored. Reasonable longevity approaching 10 years.||As for the minimal preparation bridge. Additionally destructive of tooth tissue.|
|Implant retained crown||Conservative of tooth tissue; no abutment preparation needed. Long-term survival rates are good.||Expensive. Involves surgical procedures as well as laboratory fees. Not an immediate result; may take 6–9 months to complete. Patient may require temporary prosthesis while implant integrates. Good quality bone and sufficient alveolar width and height required.|
▪ What specific features of importance with regard to restoration would you examine? Explain why.
The degree of bone loss of the edentulous alveolar ridge is important. If this is extensively resorbed, an elongate pontic would be necessary to hide the bone loss. This might well be unacceptable if the pontic is easily seen during talking or smiling. This problem can be overcome with ridge augmentation prior to placement of the bridge, but this would prolong the treatment and make it considerably more complex. A diagnostic wax-up may help the patient visualize the potential result if resorption is a problem or the appearance is critical.
Size of existing restorations in potential abutment tooth. This is the most important consideration for minimal preparation bridges which require either no restorations or only small restorations in abutment teeth. Extensively restored teeth leave little natural tooth tissue to supply retention for conventio/>
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