Post Space Calculator

Post length and diameter from root anatomy.

Medical Disclaimer

This calculator is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about your health. Never disregard professional medical advice or delay seeking it because of results from this tool.

Inputs

Root length (mm)

Root diameter at mid-root (mm)

Crown-to-root ratio

Remaining coronal structure (mm)

Tab to move between fields

Results

How the result changes with Root length (mm)

Root length (mm)	Recommended post length (mm)
10	6
16	12
22	18
28	24

What each input means

Root length (mm): Total root length measured radiographically.
Root diameter at mid-root (mm): Mesiodistal root diameter at the mid-root level.
Crown-to-root ratio: Clinical crown length divided by root length.
Remaining coronal structure (mm): Height of sound tooth structure above the margin.

What each result means

Recommended post length (mm): Optimal post length preserving apical seal.
Max post diameter (mm): Maximum post diameter (1/3 of root width).
Apical seal remaining (mm): GP seal preserved at the apex.
Ferrule adequate (0/1): 1 = adequate ferrule (>=2mm coronal structure).
Drill size (Peeso #): Recommended Peeso reamer size for post space preparation.
Perforation risk (0-100): Relative risk of root perforation during post space preparation.

How this is calculated

Worked example, using the default values

Identify Input Parameters
4 parameters
Root length (mm) = 16, Root diameter at mid-root (mm) = 4, Crown-to-root ratio = 1, Remaining coronal structure (mm) = 2 = 4 input(s) provided
Calculate Recommended post length
Recommended post length
12 = 12
Calculate Max post diameter
Max post diameter
1.3 = 1.3
Calculate Apical seal remaining
Apical seal remaining
4 = 4