DT U.S. Edition, Nov./Dec. 2010, Vol. 5, No. 23

sis and is affected by it. Many local and prosthetic/restorative factors have a direct effect on the prognosis for individual teeth in addition to any overall systemic or environ- mental factors that may be pres- ent.1,2,5,6 It was found that attachment loss, probing depth, furcation involve- ment, crown-to-root ratio, fixed abutment status and percent bone loss are the most important factors in determining tooth loss.5,25 • Deep probing depth and attach- ment loss. Deep probing depths and attachment loss are associated with future periodontal breakdown due to limited access for maintenance and opportunistic changes in the environment to favor periodon- tal pathogens.1,26,27 Probing depths greater than 5 mm were difficult to maintain as healthy and had more residual plaque and calculus.28 • Crown-root ratio. Crown-root ratio is also a measure of attach- ment loss, especially when dealing with short roots. The example on this page demonstrates poor crown- root ratio related to a developmental anomaly in a patient with short roots (Fig. 2). • Furcation invasions. The great- er the amount of attachment loss in the furcation, the worse the long- term prognosis for that tooth. Teeth with minimal (Class I) or no furca- tion invasions generally have a good prognosis. Teeth with complete loss of bone in the coronal aspect of the furca- tion (Class III) generally have a poor prognosis, and regeneration of this type of defect is not predictable for most clinical situations. There- fore, teeth with Class III furcation have an unfavorable treatment out- come.2,8 • Anatomic factors. Teeth such as the maxillary premolars, which have pronounced root concavities, are also more difficult to instrument and maintain, and likewise have a worse prognosis than teeth with relatively straight roots.8 • Tooth mobility. While some authors have found that increased mobility is a factor that negatively influences the survival of a peri- odontally affected tooth5 , others describe no association between tooth mobility and treatment out- come. Severe mobility of a tooth is generally an indicator of a poor long-term prognosis.1,2 • Restorative and prosthetic fac- tors. Overhanging restorations and ill-fitting crown margins represent an area for plaque retention and increased prevalence of periodontal lesions.29 Depending on the supragingival or subgingival location of such fac- tors, their influence on the risk for disease progression and periodontal prognosis has to be considered.30 Fixed abutment status is a mea- sure of occlusal load and also of the patient’s ability to perform plaque Clinical DENTAL TRIBUNE | Nov./Dec. 201018A AD f DT page 16A Fig. 2: Short roots. Fig. 1: Non-controlled type 2 diabetes in a 42-year-old patient. g DT page 20A