Last year around this time, we received word that my stepson would be needing braces. Not only would he be needing braces, but we'd be needing to contribute a pretty hefty chunk towards that expense. Ouch.
In an intact family, those kinds of things crop up and families deal with them as necessary on a rolling basis. Somehow, in blended family the issue of braces/orthodontia is a pretty common struggle. Several factors likely contribute but most likely the noncustodial parent isn't as "in the loop" as far as dental appointments and discussions of treatment plans with the dentist or orthodontist.
That is why sometimes, the first the noncustodial parent hears about it is when it's a foregone conclusion and it's time to pay half… NOW!
So what can you do?
What we've found helpful is if you're in a high conflict situation, don't hesitate to communicate directly with the orthodontist's office. It seems they are used to this – and my stepson's ortho was able to work directly with my husband to coordinate payment (which was far easier for us). Prior to the orthodontist stage, it probably wouldn't hurt to stay in touch with what is going on at the child's regular dental appointments. Dentists are usually able to tell fairly early on when braces might be warranted, so you can have a head's up and it's not such a surprise.
What has worked for you?
Photo credit: Drew Herron on Flickr

I have all of my medical monies taken out of my paycheck and put into a flex account.
Granted, it does take 150$ a month away from the household, but it is pre-tax and it helps pay for the medical expenses so that it is not a larger burden on the blended family.
Once we get married I plan on putting his son on my insurance plan since I pay one price for ALL children and it would save on insurance costs AND we can keep track of all insurance co-pays to his ex-wife.
My guy goes to all of his son's dr's appt's, however he has not gone to the dentist appts. I just took my toddlers to the same dentist and he found out that she is not paying a co-pay (like she said she was) because I did not pay one when I left, I just got a bill. So it is a whole new area of medical expenses I had never considered when joining a blended family.
Great question. Braces are expensive… ick!