Attrition takes place from the wearing down of the incisal or occlusal surfaces due to mastication. This change is seen both macroscopically and microscopically.
Periodontosis, loosening of the tooth, or continuous eruption, is characterized by changes in the attachment of the tooth. This change again, is seen both macroscopically and microscopically.
Secondary dentin may develop within the pulp cavity; partly as a direct sign of aging and partly as a reaction against pathologic conditions like caries and paradentosis. This change is seen only in the microscopic sections.
Cementum apposition may take place at the root and around it, particularly in connection with paradentosis. It is seen only in the microscopic sections.
Root resorption may involve both cementum and dentin.
Transparency of the root increases with age and is best appreciated in ground sections.
The purpose of the present study was to present a method for assessing the chronological age based on the relationship between age and measurement of the pulp/tooth area ratio on single-rooted teeth, using orthopantomographs and a computer-aided drafting program.
This study was a retrospective study of 200 rotational pantomographs collected from patients coming to the various departments of V. S. Dental College and Hospital, Bangalore. These radiographs were taken as a part of the routine treatment that is being rendered to the patient.
Pantomographs selected were of the patients aged between 18 and 72 years.
The selected tooth on the orthopantomograph, the right maxillary canine was fully erupted into the oral cavity.
The root of the canine was fully formed.
Teeth with any pathology, such as, caries or periodontitis or periapical lesions, which would alter the surface area of the tooth.
Malaligned canines or rotated canines.
Canines with any prosthetic fittings.
The selected orthopantomographs were digitized using ASTRA 4000 U X-ray scanner and the images were recorded in a computer file. Radiographic images of the canine were then processed using computer-aided program AutoCAD 2000.
Twenty points were marked on the surface of the tooth outline and ten points were marked on the surface of the pulp outline of the right maxillary canine, to obtain the tooth surface area and the pulp surface area, respectively.
The chronological age of the patient was calculated by substracting the date of radiograph from the date of birth of the patient.
Morphological variables and the chronological age of the patient were entered in Microsoft Excel spread sheet for use of age estimation. Correlation coefficient was evaluated between age and predictive variable, that is, pulp/tooth surface area. A multiple linear regression model was then developed to estimate the age of the individual.
The estimated age was then compared with the chronological age of the individual.
Student's t test was used to compare the estimated age and chronological age of the different groups and found the P value to be 0.86 [Table 1]. Since P > 0.05, it was concluded that there is no significant difference between estimated age and chronological age. The correlation coefficient 'r' between the two variables, that is, the chronological age and the estimated age, was found to be 0.99, which indicated that the two variables are linearly related to each other [Table 1],[Figure 1].
In this study, the entire sample was distributed into three different age groups - 18-30, 31-50, and 51-70 years - to observe the effect of this method on different age groups. The observed correlation coefficients 'r' were 0.89, 0.97, and 0.96, respectively, which indicated that the chronological age and the estimated age in all the three age groups were closely related to each other [Table 2],[Table 3],[Table 4],[Figure 2],[Figure 3],[Figure 4].
Similarly, the effect of gender on age estimation was also determined in this study, and found that gender had no significant influence on age [Table 5] and [Table 6] [Figure 5] and [Figure 6].
In our study, the analyzed results showed that the P value was >0.05 [Table 1], which meant that there is no significant difference between estimated age and chronological age. This was in accordance to the previous studies conducted by Cameriere et al.  and Bosmans et al .  The correlation coefficient 'r' was found to be 0.99 [Table 1]. This confirms that estimating the age using pulp/tooth area ratio is relatively accurate.
Later, Bosmans et al.  applied Kvaal's dental age calculation technique on panoramic dental radiographs, thereby avoiding the cumbersome process of taking many periapical radiographs. They also in their study found pulp width to be closely associated with age.
In this study, the entire sample was distributed into three different age groups - 18-30, 31-50, and 51-70 years. The observed correlation coefficients 'r' were 0.89, 0.97, and 0.96 [Table 2],[Table 3],[Table 4], respectively, which indicated that the chronological age and the estimated age in all the three age groups were closely related to each other.
In the due course of our study, we however found that, this method of age estimation has certain limitations. This method of age estimation cannot be employed in multirooted teeth, as accurate measurements of multirooted teeth were difficult to perform. Similarly, as the curved arch of the jaw is projected on to a flat film, there will always be certain amount of distortion when measuring the image presented there. To compensate for the amount of distortion, we chose the tooth of study on a particular side of the radiograph, that is, we chose only the right maxillary canine, so that the amount of distortion is uniform in all the radiographs. Therefore, it is impending to be seen whether this distortion has any effect on accuracy of age estimation. Apart from the aforementioned limitations, the cost involved in setting up of the software is also high. So it is suggested that in future, further studies can be taken up to estimate the age using other single-rooted teeth and then determine the completeness of this method of age estimation, so that it may become a method of choice for forensic odontologists on a regular basis.
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