ABSTRACT
The objectives of this study were to determine the normal mean value of the root-crown (R/C ratios) in Malay patients and their variations by gender and dental arch from orthopantomogram radiographs (OPGs). Two thousand nine hundred and twenty teeth with fully developed roots were measured from 112 OPGs. Subjects with history of maxillofacial trauma or orthodontic therapy were excluded. The mean age of the subjects was 19.1 (SD 2.08) years old for males while females 18.9 (SD 2.19) years old in the range from 15 to 22 years old. The intra-examiner reproducibility of the assessment method was good (Intraclass correlation coefficient 0.81). Results of this study showed that there was no significant difference between R/C ratios of males and females groups. However, the ratios of the antagonist teeth for both males and females were significantly greater in the mandible than in the maxilla (p<0.05 for right and left lateral incisors and right first premolars in male; p<0.001 for all other teeth). In both gender, the highest R/C ratio was mandibular second premolars and the lowest R/C ratio were maxillary central incisors. The rootcrown ratio could be used as a baseline data and reference to help in orthodontic diagnosis, treatment planning and prognosis as well as evaluation developmental root deficiency.