Saturday, February 18, 2017

Reflections on mirrors for dental photography

Quality mirrors are a must for dental photography. Here's what to look for:
  1. Front surface plating - The best image quality you will get is when the reflective plating is ON TOP of the glass, not under it.  Rhodium is affordable and effective, though there are better choices I'll discuss later. We all know this on some level, that's why we all buy front surface mouth mirrors for our day to day dentistry.

    The downside of front surface mirrors is scratch resistance, or the lack thereof.  So baby your mirrors.  More on that later. All mirrors eat 50-80% of the flash lighting they receive. Better mirrors are more reflective, but also more expensive.
  2. The occlusal arch and buccal mirrors.  If I had to have only two shapes, it would be the occlusal arch mirror (which looks like a large rounded rectangle) and the buccal mirror (which happens to look like a lower case "b").
Occlusal mirror - pick a long one - easier to keep your hands out of the picture

Buccal mirror - looks like a letter "b", "d" or "p"
I can shoot more different shots with this mirror than any other.

Where to buy cheap mirrors

The eBay option.  We have several of the mirrors linked above.  The image quality is decent. They are not exceptionally bright, but usable. The one noticeably concession is the edging.  It's not rough enough to cut anyone, but it's just not as smooth, either. 

Where to get better mirrors.  

If you want higher quality mirrors, go to photomed.  Their titanium surface mirrors are noticeably brighter.  You will pay more, but they should last longer, too.

Why would you want a brighter mirror? (added 7/11/2019)
If you're ever used Zirc's Crystal mouth mirrors, you already know the answer to this.  If not, get them...they are a life changer.

A brighter mirror reflects more light.  More light makes your autofocus significantly faster.  It makes aiming easier, also.  Your typical intraoral flash has more than enough power to compensate for a dull mirror, BUT the recycle time will suffer if you have a dim mirror.  If you press the shutter while the flash is recycling, you'll get a dark picture.

For thsoe using continuous LED lighting, a brighter mirror is even more important.  The light of a flash is very brief, so your effective shutter speed ALWAYS freezes any movement.  But if you have a mirror that is half as brighter, you'll get twice the motion blur.  Reflecting more light allows your camera to using faster shutter speeds.  Exposing the sensor to light for a briefer period prevents shutter shake and motion blur.

In my informal testing, the brightest titanium mirror in my collection was almost a full stop (as in twice as) brighter than my dullest rhodium mirrors.  It would be another half stop brighter than polished steel.

A more efficient mirror becomes more and more relevant as more and more people shoot with mirrorless cameras and smartphones, both of which need more light than SLR's to focus.

Mirrors to avoid:

Practicon sells "DoctorEyes" mirrors.  Worst purchase ever.  They are rear plated, so you frequently get a double image.  Avoid them at all costs.

Stainless steel mirrors - not only are not as reflective, polished stainless steel rapid degrades as the mirror accumulates scratches.  Stick with rhodium plated mirrors, or better yet, titanium surface.

Proper care 

Wrap the mirror in a small micro-fiber towel, then into the sterilization pouch.  When you unwrap it, spray a little eyeglass cleaner and wipe it with the towel before use.  (sometimes we steam clean the mirrors, which also makes the warmer and more fog resistant.)  After use, spray and wipe again, then wrap the towel around the mirror again.  Put it in the pouch for autoclaving.  DO NOT put your mirror in the ultrasonic cleaning unit with your other instruments.    

Thanks for reading!

Friday, February 10, 2017

Slow speed contra angles on eBay: a review

It's time for our next stop along the e-bay Orient express: contra angle slow speed attachments.  I love the e-type mount, because it's an open standard used on electric handpieces, implant motors, endo motors, and really affordable slow speed air motors, too.

Shop for slow speed motors on eBay

There are three e-type contra angles we use day to day at my practice: the button, the latch, and the reciprocating for prophies.

The latch angle is the older design.  It is easy to use, but has a tendency to start coming loose.  So you have to occasionally tighten them.  You'll want to keep a small flat screwdriver around to tighten the latch, also. Visibility is relatively good because the head is really skinny.  But it never jams, and the burs always come out cleanly.  Sometimes they don't lock, so you have to tug them a bit before you use them.  Market price at time of writing was $10 a piece, so you can't really complain

Shop for latch angle contra angles on eBay

The push button is the more modern design.  The collar occasionally comes loose, as they do on all contra angles.  I use these every day for polishing composites, polishing porcelain and caries excavation.  (love the Ivoclar Optrafine for ceramics) My main grief with these is the chuck; the burs can get stuck and refuse to come out.  There are three ways to unjam them:
1) push down the button really hard on your countertop and hope it pops in
2) hold the bur with your fingers (at your own risk) and lightly push the foot pedal.  It will often spin loose
3) use the included flat tool to open up the head and wiggle the bur out.

The bur jams seem to happen more often with the push button.  I have yet to have one on the less sexy latch angles. But mentally, I just don't like the old school look of the push button.  Expect to pay about $15 per head for these push button contra angles.

Shop for push button contra angles on eBay

I'm not going to discuss the internal spray contra-angles that are selling around $35 each.  I haven't tried them because I don't have an electric handpiece.  You're welcome to try them out and report back.

I talked about the reciprocating 4:1 contra angle in my previous post about prophies.  But here's a recap:

These $75-100 contra-angles were designed for endo, but they will work great with prophy polishing.  The 4:1 gear reduction means even a lead foot will spin it at 5,000 rpm tops.  Gear reduction also makes it harder to stall when you bear down on those stains.  (be careful--heavy pressure on the polisher heats up teeth quickly) It doesn't engage as smooth as a $900 hygiene handpiece, but it's also one sixth the cost.  And like the twist prophy angles, it reciprocates, so it's almost impossible to fling paste around.

Shop for 4:1 reciprocating contra angles on eBay

And yes, you can buy latch angle prophy cups, and they are only 8 cents.

That's all I have for now.  I haven't tried any of the 1:5 high speed contra angles or the internal spray models, both of which are intended for owners of electric high speed micromotors like the Bien Air MX2.