Orthodmd wrote:

    Uh oh.  I'm on aligner #16 (out of 18).  I am concerned about
retention.  Even at this stage, if the aligner is out for a couple of
hours, they don't go back in passively.  My understanding is that their
retainer is a heavy-duty version of the last aligner.
    I currently have some pretty significant prematurities in protrusive,
which is perhaps complicated by an old R. condylar neck fracture
(therefore no translation).
    How do you accomplish retention on your adult invisalign cases?

Steve

My protocol for retention is the same in Invisalign cases as it is in other
adult nonInvisalign cases.  Interestingly this is one of my favorite subjects
when I teach residents.  

The idea of removable retainers is dated technology all based on what was
available pre-Buonocore.  Hawley type retainers were used to move teeth prior
to Ed Angle and his development of the edgewise appliance.  After fixed braces
came into fashion, we as a profession continued to use Hawleys as retainers
because "salt and pepper" construction of retainers was all that was available.
As you both appreciate, a lot of what we do as dentists is due to what our
mentors did and it is carried over without much critical thought.

Then came Dr. Buonocore and his use of acid etch.  I graduated Tufts ortho in
1980 and even after that date, certain faculty including the chair were
emphasizing the importance of knowing how to fit bands properly and "there was
nothing better" than a fully banded appliance.  All students as recently as
1983 were required to treat two cases fully banded to graduate.  I was in
practice three years at that point and did not own upper or lower anterior
bands.  I was fully committed to acid etch.

When you ask older faculty what kind of retainers they use, they frequently say
either Hawleys or suckdowns.  Why not bonded (fixed)?  Answers are: "They come
off too frequently, patients may swallow them, you are wedded to that patient
for life, they have to be kept in recall forever, etc."

Bull!  It is merely an inability to integrate technology into their practices.
Cosmetic dentistry has fully used acid etch to change the face of restorative
dentistry.  Unfortunately, not all orthodontists have moved comparably in the
same direction at the same speed.

Thoughts for you and brother Mark:

1.    tooth movement after braces or Invisalign tends to be a geometric
reduction.  Think of a half life graft.  Most of the movement occurs during the
first thirty days and then less and less over time.  If you take out your
retainers/Aligners there will be substantial rebound in the first 30 days and
then less and less.
2.    any type of retainer worn faithfully for 30 days will substantially
reduce future movement.
3.    the best type of retainer is fixed although good use could be made of a
"suckdown" (see below).
4.    The ideal fixed retainer (assuming no severe initial rotations, no
extraction of an incisor and not initial spacing) would be one in which an 032
" round wire is carefully formed to the inside of the lower incisors and then
bonded to the canines only.  This is very hygienic and a the lower incisors can
be flossed by passing the floss under the wire only once.
5.    this technique is operator sensitive and there is a learning curve.
Obviously, moisture control if paramount.
6.    essentially, you hold the wire in place with floss or some use putty
(polyvinyl) or Mortite.  Etch the canines, dry and use a sealent (I like Ortho
Solo a Kerr product similar to a restorative product by Kerr with a similar
name?).  Use a very small amount of Revolution to hold the wire in place and
light cure.  This stabilizes the wire for the rest of the procedure
7.    Ideally, you can use modified Concise (modified by the addition of
sealent to make it flow a little.)  This is probably the strongest thing to do
but unavailable to most restorative guys without an investment in old
technology.  Alternatively, use a minimally flowable material with good
strength and durability.  Contour with burs to a smooth shape.
8.    If you want to do every tooth, use a more flexible wire like 021
Wildcat and follow the above guidelines.  The best wire to use and one that is
changing ortho for those that use it is from Reliance Orthodontics and is white
gold chain.  You bond it as above but the chain aspect of it gives enough play
that the teeth stay straight but the wire almost adapts itself and there is
less chance of accidental breakage.  (Can't remember the exact name Flextech
something or other
9.    If you want to use the suckdown removable type retainer, ask the
patient to wear that all the time for a week.  Then 16 hours/day for six weeks
then enough to keep the teeth straight.  During the initial six weeks or so I
want to strip the lower incisor contacts with a thin diamond wheel to reduce
the pressure on the teeth to move.  Successful treatment would be light
contacts and straight teeth after six months.
10.    the beauty of removable retention is that it makes the patient
responsible for retention.  If they skip a couple of days and the retainer
stops fitting, you should try to convince them that their teeth will return to
straight if they will just wear the removable retainer until it fits again.
This may hurt a little but it will work as a minipositioner and restraighten
the teeth
11.    Finally, the negative aspect of removable retention is that it makes
the patient responsible for retention.  Your success is in the patient's hands.
If the lower teeth move, the hygienist does not say to herself: "This patient
did not wear their retainer."  She says: "Crappy orthodontics."  I am unwilling
to have my reputation in the patient's control and I think fixed retention is
the max use of technology so I use all fixed retainers.
12.    Finally, finally.  I use fixed retention upper and lower on all adults
but only on some kids.  All kids get a fixed lower but only some get a fixed
upper.  The rest get suckdowns.  My friend has recently gone to fixed upper and
lower on everyone.  I will have to see how that works.  It is a great idea.  My
neice was treated on Long Island 10 years ago and the orthos that treated her
used fixed upper and lower retainers.  They told me that it just was easier in
their demographic area to take control away from the patients.

Charlie Ruff, DMD
Specialist in Orthodontics
Diplomate American Board of Orthodontics