You're welcome.  Has it been a while since your last cleaning?  The
dental tartar buildup can be insidious in it's formation.  You may not
notice it accumulating and taking the place of where the gums normally
are.  One other possibility might be that during your previous
cleanings, the interproximal (in between) tartar deposits may have
been missed and only cleaned off at your current appointment.  It's
difficult to say.

The hygienist might have accidentally lopped off some of your gingiva
during scaling.  Sometimes the teeth are rotated / angled a little
making the gums in between get in the way of the instruments.  If a
hygienist is not careful, damage to the delicate gingival papillae can
occur while under anesthetic or not.  I've encountered some aggressive
hygienists in my time, and trust me it happens.  :-(  Keep in mind
that teeth tend to shift, rotate and move around a bit over the years
so a gap that wasn't there before may have developed recently.

The ultrasonic scaler will give off a high pitched whistley whine
that's fairly constant as long as it's activated.  There is also
constant water spray that accompanies it for cooling and clearing
purposes.  The hygienist also uses a slow speed prophy handpiece that
might sound like a drill, but that's normally used just for polishing
with a rubber cup.  There is also a Prophy Jet machine that some use,
but I don't think it sounds like a drill.

I doubt that the hygienist would be using a high speed handpiece
unless they have one of those ancient high speed ultrasonic
attachments.  It uses the high speed air to cause the tip of the
cleaning instrument to vibrate similar to an electric Cavitron.

Other off the wall possibilities might be that an inexperienced,
aggressive hygienist used a Cavitron on high without water spray and
really went to town reshaping the enamel on the teeth for some
reason.  They could have taken a high speed with a bur to open up a
gap I suppose, but without anesthetic you likely would have felt it.
These things would have opened up the hygienist to some legal issues
which I don't think they would intentionally want.

If you are still concerned, you could ask your dentist to check the
teeth to see if they have normal anatomy still.  It should be fairly
easy to check to see if tooth structure of the lower incisors has been
removed since they are small teeth to begin with.

Zzzdentist
www.dentalminds.com