Objective: To observe the morphological changes of root canals with aging in maxillary first premolars by using cone-beam computerized tomography(CBCT)in order to facilitate endodontic management of root canals in various aged patients.
Methods: The digital CBCT data of the maxillary first premolars in 405 cases from the patients in Oral Medical Center of The First Affiliated Hospital, Jinan University from March 2011 to June 2015 were collected. The CBCT images were divided into 6 groups according to the patients' ages: groups 11-20, 21-30, 31-40, 41-50, 51-60 and >60 years-olds, respectively. Changes of morphologies of root canals with aging including such parameters as types of the root canal, incidence of double root canals in single rooted teeth, distance between both root canal orifices of double rooted canals, and morphological change of the cross section of roots. Chi-square test and liner trend test were adopted in statistical analysis in the present study.
Results: The distribution of various types of the root canals were significantly different amongst various aged groups(P<0.05). Type Ⅳ is the most common type(210/405, 51.8%), and the following groups were typeⅡ(65/405, 16.0%), typeⅠ(55/405, 13.6%)and type Ⅲ(27/405, 6.7%). Along with aging, the percentages of type Ⅰ and type Ⅲ decreased while type Ⅱ increased. However, there were no remarkable changes of type Ⅳ observed. The incidence of double rooted canals in single rooted teeth gradually increased with aging especially in 20-years-old and above groups, e.g. 51.7%(31/60)in group 11-20 years-olds and 83.0%(44/53)in group 21-30 years-olds. However, there was no significant increase observed after the age of 40. The distance between both root canal orifices of double rooted canals became shorter with aging except in groups of 40-years-olds and above. The morphologies of the cross sections in most aged groups were flat shaped(1 020/2 105, 48.5%)and oval shape(594/2 105, 28.2%). Along with aging, the percentage of circular shape gradually increased while flat and oval shapes decreased.
Conclusions: The morphology of root canal could be clearly showed by the CBCT images. The change of morphologies of the root canals in maxillary first premolars was significantly related to aging. Along with aging, the morphology of the root canal became more and more complicated.