J Adv Prosthodont.  2014 Jun;6(3):171-176. 10.4047/jap.2014.6.3.171.

Radiographic assessment of clinical root-crown ratios of permanent teeth in a healthy Korean population

• Yun HJ
• Jeong JS
• Pang NS
• Kwon IK
• Jung BY

• KMID: 2118227
• DOI: http://doi.org/10.4047/jap.2014.6.3.171

Abstract

PURPOSE
The aim of this study was to determine the absolute value of the root/crown ratio (R/C ratio) using panoramic radiographs (PRGs) in a healthy Korean population.
MATERIALS AND METHODS
In total, 99 patient radiographs (of 50 males and 49 females subjects; aged 16 to 24 years old) were examined, and 2,770 teeth were analyzed. Crown lengths and root lengths were measured with modified Lind's measurements using PACS tools by two examiners in two separate sessions two months apart. All data were analyzed using SPSS. The independent t-test was used to assess for gender differences, and the paired t-test was used to compare both arches with a significance level of P<.05.
RESULTS
The mean R/C ratios varied from 1.29 to 1.89 (male: 1.28-1.84; females: 1.31-1.94). The highest R/C ratios were recorded for the mandibular canines (1.89), followed by the maxillary canines (1.79). The lowest R/C ratios were recorded for the maxillary second molars (1.31). In comparison with the maxillary teeth (1.29-1.78), the mandibular teeth yielded the higher R/C ratio (1.47-1.89), and this difference was significant in the females (P<.05). The difference between the genders was not statistically significant, except for the maxillary central incisors, mandibular canines and mandibular first premolars.
CONCLUSION
These data may enhance the understanding of the clinical R/C ratio as a useful guideline for determining the status of teeth and the ethnic difference.

Keyword

Root/Crown ratio; Prognosis of teeth; Ethnic differences; Panoramic radiograph

MeSH Terms

Bicuspid
Crowns
Female
Humans
Incisor
Male
Molar
Tooth*

Figure

• 

  Fig. 1 A schematic drawing presenting the method of measuring the crown height and root length for the R/C ratio. Crh: crown height, Rl: root length, a: apical reference line, i: incisal reference line, m: midpoint.

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