Crown to implant ratio
Crown to implant ratio does not seem to be really appropriate since increasing implant length does little to strengthen the implant past about 5mm. However, if want to measure your C/I ratio then you should measure from most coronal bone contact to most coronal surface of restoration. Therefore if the implant experiences bone loss the crown to implant ratio will get worse.
We feel it is not the crown to implant ration that causes an issue as much as it is the length of the prosthetic. Longer implants are not stronger, so implant length is not what is supporting the prosthetic once healing has occurred.
C/I ratio systemic reviews and other research
Pellizzer JPD 2021 Systemic review and meta analysis shows no impact on implant survival. It does suggest marginal bone loss with increasing crown to implant ratio.
- NOT a risk factor for biological complications
- If favorable force orientation and load distribution, little prosthetic risk even if 2-3 C/I ratio
- Can be a prosthetic risk for single abutment and crown loosing if C/I 1.5
- Can be a prosthetic risk for 2mm wide abutment fracture if C/I 2
- No biomechanical risk
- No impact on survival
- No impact on marginal bone loss
When does the crown to implant ratio matter?
Misch says if crown abutment heights approach 15mm there is an increase in prosthetic issues. DT thread stating This makes as sense as it is not so much a ratio but a lever arm and the length of the prosthetic is likely all that matters. This coincides with Batak JP 2021 finding that 14mm tall crowns have higher screw fracture rates than the 10 and the 6mm crowns.
To learn about splinted dental implants check our blog on splinted vs non-splinted dental implants.