A gauge for measuring and/or marking teeth or models of teeth for the determination of the placement of attachments for orthodontic braces. The gauge has a first arm with a gauge element with a longitudinal extension portion lying on a first axis and a vertical extension portion extending generally perpendicularly from the first axis of the longitudinal extension portion. The gauge has a second arm which has a pointer or marking element at an end thereof, the pointer element having a tip which is spaced apart from the longitudinal extension portion of the first arm, the first and second arm being connected together to maintain the spaced apart relationship between the tip of marking element and the longitudinal extension portion with the vertical extension portion extending towards the pointer or marking element. The invention also provides a gauge element for converting a bow divider into a gauge for measuring and/or marking teeth for the determination of the placement of attachments for orthodontic braces. The gauge element has an elongate extension portion lying on a first axis and a vertical extension portion extending generally perpendicularly to the first axis of the elongate extension portion with the vertical extension portion extending outwardly between about 2.00 mm and 3.00 mm from the longitudinal extension portion.