Click here to enlarge imageImplants should also be considered as an alternative when more expensive procedures are contemplated in an attempt to save or maintain a compromised tooth. Traditional methods to save a tooth have increased in cost over the years.
For example, multirooted endodontic therapy now approaches the cost of an implant surgery. When functional crown lengthening and endodontic post treatment is also required, the fees are usually greater than extraction and implant insertion. Treatment planning should take into consideration the natural tooth that requires periodontal therapy as well as multiple other aspects of treatment which compromise the long-term success and are cost prohibitive for the service provided.
A tooth may be considered for extraction because of prosthetic, endodontic, or periodontal considerations. On rare occasions, tooth extraction may even be considered rather than orthodontics to restore the teeth in a more esthetic or functional position. The primary discussions related to this article will be for periodontal considerations, which may warrant tooth extraction and implant restoration.
0-, 5-, 10-year rule
The dentist evaluates the natural teeth for their quality of health with widely used prosthetic, periodontal, and endodontic indexes. After this is accomplished, an estimate of longevity may be used to decide whether to extract or to treat and maintain the tooth, following a 0-, 5-, 10-year rule.
If the natural tooth has a favorable prognosis for more than 10 years (after it is returned to health), it is most often included in the treatment plan. The tooth under these conditions may even be considered to join an implant within the same prosthesis.
For example, the tooth may act as “a living pontic” in the final restoration, surrounded by sufficient implant support. The decision to use it or not as an abutment requires additional information, but few reasons support removal of the tooth to restore the partially edentulous patient.
A less than 5-year prognosis for a natural tooth despite restorative or periodontal therapy, warrants extraction of the tooth, with grafting and planning for implant abutment support as part of the initial treatment plan. This treatment scenario may often be faster, easier, less traumatic, and less expensive compared with maintaining a questionable tooth.
When probing depths are above 7 to 8 mm with bleeding upon probing, the teeth are usually placed in a 0- to 5-year prognosis. Maxillary molars with Grade II or III furca are at a higher risk of complications and are often lost within 5 years. If hygiene is poor with Grade II or III furca involvement in molars, the tooth most often is considered in the 0- to 5-year category. This is especially true when other teeth in the same quadrant are missing or hopeless.
A periodontal abscess results in rapid periodontal attachment loss and active bone destruction, and often reduces the longevity of a tooth. When a history of repeated abscess formation is observed from a tooth, a hopeless prognosis is usually assigned.
If the natural tooth prognosis (after periodontal, endodontic, or restorative therapy when necessary) is in the 5- to 10-year range, the treatment decisions are more nebulous.
In general, deep pocket depths of up to 7 to 8 mm with bleeding upon probing is an indicator of periodontal disease activity, and longitudinal studies suggest a poor prognosis. The teeth under these conditions may be placed in the 5- to 10-year category. Molars with Grade I furcation involvement often are also placed in the 5- to 10-year prognosis category.
Independent implant supported prostheses are indicated to replace any missing teeth in the 5- to 10-year category. The placement of as many implants as possible to support an independent prosthesis around the tooth, with treatment alternatives that will permit removal of the tooth without sacrificing the restoration, is indicated.
Of special note is teeth in the 5- to 10-year category next to a multiple edentulous site. A natural tooth distant from the future implant restoration is less likely to affect the implant reconstruction and alter the treatment sequences.
However, failure of a natural tooth adjacent to an implant site may cause failure of the adjacent implant and almost always (whether implant failure occurs or not) causes the restoration to be delayed and compromised. Therefore, if the practitioner is not sure whether the adjacent tooth to an edentulous site is in the 0- to 5-year or 5- to 10-year category, the tooth more often should be considered to have the poorer prognosis. Table 1 summarizes the decision making protocol involving a natural tooth abutment.