Lamina Dura: How do you measure the distance?

Last Updated: May 04, 2016

Wondering if with the use of the CT everyone is still maintaining the 1.5mm rule from the tooth to the implant? With a CT I have a lot of times when my cases show the lamina dura being closer than 1.5mm.
When you are measuring do you run the risk of devitalizing the tooth if you are closer than 1.5mm to the lamina dura? Or do you measure to the actual root surface?

Also, wondering about this case below, in particular.Previously endo / post treated area that failed and required extraction. Patient is ready for implant placement, but curvature of the root on #5 is limiting the size of the implant placement to 3.0mm diameter implant, and even with this it’s less than 1mm to the adjacent teeth. I don’t think it will be a problem as both of the adjacent teeth are Root canal treated. What do you recommend? Thanks for the thoughts and input.

4 Comments on Lamina Dura: How do you measure the distance?

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CRS

05/05/2016

I'm still struggling with all the artifact on #3 and #6. I think if you scroll down and see where the apex of #4 is usually more to the palate may guide you but not so in this case. I think the implant looks too palatal but I see how you lining up with the lower tooth. I don't think it will matter much if you nick the apex since it has a root canal. I think the emergence profile is key, still a blind procedure just drill at low rpm so you can get a feel. Good luck, I'm still struggling with CBCT for dental diagnosis need to clinically correlate I mainly use it for the bone width.

Dennis Flanagan DDS MSc

05/10/2016

#3 and 5 may have residual vegetative bacteria at the apices as seen on the radiolucencies. It may be good to explain to this to the patient, there may be a failure. It may be good to consider extraction of #3 and 5 and thorough debridement and subsequent implant placement. This site is dangerous. #6 is a problem. This patient appears to be osseously infested. Dennis Flanagan DDS MSc

Kastytis Zymantas

05/11/2016

The 1.5mm rule to maintain that distance between an implant and a natural tooth will not go away soon. The rule is primarily for the crestal portion of the implant because of the biologic width. You have a vertical as well as horizontal component to the biologic width. You may be able to cheat a little on that dimension if you use a platform switch implant but you are not going to get much if any platform switch with a 3.0 mm implant. You can use an implant that is placed about 1-1.5mm supracrestal to provide some biologic width so that the bone around the implant does not break down. You would not have an issue if you get closer than 1.5mm more apically. #6 needs rct asap.

Michael Igor Shnayder

05/11/2016

That's an interesting concept to place supracrestally. Not sure if I have ever done that in the past. Do you have any cases that you can share. Thanks

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