Use of crown height of the maxillary first molar tooth to approximate the age of horses.

The research investigates the relationship between the crown height of a horse’s first maxillary molar tooth and its age, with the aim of coming up with a model for calculating a horse’s age based on this tooth’s crown height. Measurements were taken from computerized tomography (CT) and radiographic images of horse heads and then analyzed using linear regression.

Methodology

• The sample for this study consisted of CT (n=735) and radiographic images (35) of horse heads.
• The crown height of the left and right maxillary first molar teeth (M1) was measured digitally from axial CT views. If a lateral radiographic image was available, the height was measured from that as well.
• Linear regression analysis was used to identify any factors associated with crown height, including age, sex, and breed.
• The researchers then used half of their data set to create a regression model for predicting a horse’s age based on M1 crown height, and the remaining half to validate the model’s accuracy.

Findings

• The study found that M1 crown height decreased as a horse aged, but this decrease slowed as the horse became older.
• There were also differences in M1 crown height according to sex and breed.
• The model was most accurate for horses under 10 years old, with an average overestimation of 0.1 years.
• The correlation between M1 crown height measurements from radiographic and CT images was 0.91. On average, the radiographic measurements were 2.5 mm greater than the CT measurements.

Conclusions and Implications

• The researchers concluded that it’s possible to use M1 crown height to estimate a horse’s age.
• The results from the CT images correlated well with those from the radiographic images, suggesting that both could be used for this purpose.
• Further studies are needed to develop a comparable model using results from the radiographic images.