Validity of Crown - To - Root Ratio as a Prognostic Tool in Clinical Practice

Abstract

The relationship between the portion of the tooth coronal to the alveolar crest of bone compared with the portion embedded in it, has always been regarded as a vital aid in predicting the prognosis of teeth. However, controversy persists as to its impact on diagnosis and treatment planning. This article critically reviews the available literature on the crown-to-root ratio assessment and the shift in paradigm related to the criteria for evaluation of abutment use of periodontally compromised teeth. Also various treatment modalities present to improve an unfavourable crown-toroot ratio have been stated. A Medline search was completed for the time period from 1961 to 2005, along with a manual search to locate relevant peer reviewed articles and textbooks published in English. There was a scarcity of evidence-based research on the topic. Although the use of crown-toroot ratio along with other clinical indices may offer the best clinical predictors, no definite recommendations could be ascertained.

Contemporary approaches for Preventive management of compromised residual dentition “Three clinical case reports”

“…Moreover, retaining and incorporating the roots in the RPOD design decreased the dependence on tissue support and reduced the detrimental denture movements by changing the fulcrum line axis position [8] . and there is evidence that reducing the effective crown/ root ratio of teeth used as overdenture abutments has a direct impact on decreasing mobility, giving the abutment more resistance to oral forces, and improving the compromised abutment's periodontium [9] . Furthermore; using full-coverage crowns, and telescopic copings offered protection for the abutments from the hassles of the oral environment, Over and above, the FPD and the telescopic RPD frameworks provided adequate splinting for the abutments; all this hopefully could increase their life expectancy.…”

Two canine tooth supported overdenture with ready-made attachments (3 year prospective study)

“…Periodontal mobility was not to exceed Grade II (all cases were grade I or no mobility) upon patient inclusion which were changed after oral hygiene measures and crown reduction to no mobility. Change of crown/root ratio has a direct impact on decreasing mobility giving the abutment more resistance to oral forces (52,53) . Also this was declared by other authors as Renner et al (54) , they pointed out that using retained roots as overdenture abutments can prevent mobility in 50% of roots, and improve periodontal status in 25% of roots.…”