root planing lead to further complications?

Do people sometimes lose teeth after this procedure?  Are there some people who are worse off afterward?  How do they know it works? (I've been reading around and it seems that people have this done every ten years?)

[Gellia]

Hi,
Root planing and scaling is usually done for periodontal disease to remove plaque deep along the tooth surface down below the gum and along the tooth root.  The procedure itself wouldn't cause a tooth to fail but the amount of plaque removed and how deep the pockets are is an indicator of how much bone may have been already lost.  

It's the bone loss that causes the tooth to fail.  

Repeat RS&P is done because the dental pockets accumulate plaque that cannot be reached with general dental hygiene.   If you don't get it out of there, it will continue to dissolve bone until there isn't enough to support the tooth.
If the pockets are not too deep, strict oral hygiene at home can keep them clean and the procedure "may" not have to be repeated.  If the pockets are too deep, the only way to clean them is with a repeat RS&P.

Hope this helps.
My best to you,
Gellia