2. Place on the contact point and align with the centre line (see Fig.1,1A)
3. Measure the arch length on each side.
Example Fig 1B = 51mm on each arch
4. If an aim of treatment is to procline or retrocline the incisors, the ruler can be repositioned using the mid-line millimetre rule as a guide (See Fig.1A)
5. Measure individual
Mesio-Distal tooth widths with a digital calliper or dividers and add them together.
The total is the actual arch length required to align the teeth. (See Fig.2)
6. By subtracting the measured arch length from the total tooth widths you can determine how much space is required for alignment.
Example Fig.1
Arch Length = 2 x 51mm = 102mm
Tooth Measurements = 2 x 55mm = 110mm
Difference = 8mm = Space required to align the arch
Sold individually.