Dr. Mark Yamamoto: our TMJ Expert Dentist

Dentist Huntington Beach Orange County California

Dr. Mark Yamamoto – Dentist Huntington Beach, Orange County California

Dr. Yamamoto: Good morning. I talked a lot about TMJ in the past. So I thought this morning I would just talk about one technical issue and that is the electric hand piece. They’ve been around for a while, but they’ve gotten better and better. I thought you might want to see what’s going on with them.

We have a new and improved design and the latest hand piece is the electric drill. That’s what we use the dental drill, has many attributes. It’s quieter, less likely to bog down and it cuts smoother preparations. When you do a crown preparation, it comes out nicer, smoother, and cleaner. It’s well made and the USC School of Dentistry has adopted it for use in the student and graduate clinics. So there it is.

Inside of here is an electric motor that makes it spin. It can go up to 200,000 RPM.

Man: Wow! Zero to 60?

Dr. Yamamoto: The speed is controllable with the dials. It adapts to the task at hand and it has greater control. Especially when you cut through enamel or you’re doing a crown preparation. It’s a lot smoother, easier, and you have better control. This is the old windmill. That’s the drill that you hear.

Woman: You don’t want to hear.

Dr. Yamamoto: Can you hear it?

Man: Yeah.

Dr. Yamamoto: Okay. This is electric. A little different.

Woman: I don’t like that sound.

Dr. Yamamoto: Okay. As a dentist of 45 years to transition to the new hand piece, I’ve been told it’s difficult for some practitioners, but I found it very easy because it does a very smooth job. When I do difficult procedures where I have to take out hard materials like old composite, it’s much easier. So that’s the pep talk for what’s new in dentistry. I have to go back and set up the other one, the new one.

Woman: You see someone using this technology. It’s working. We’ve had problems.

Woman: That’s his drill. It’s still a drill.

Woman: Still a drill.

Woman: I don’t like that.

Woman: All right, Gill, so you pumped us all up! We’re all pumped up. Physically, we’re not, but emotionally we are.

Dr. Yamamoto: You all don’t like blood and gore so I picked a topic in dentistry that is interesting, new to some and to some dentists still don’t understand it even though the technology and the proof has been around for about three decades. I still encounter dentists who argue about the existence of what we call and abfraction.

An abfraction is a defect at the cemental enamel junction. That just means where the enamel ends on your tooth and touches the root, that junction develops defects if you have malocclusion. If you have a crooked bite or is you have a stress that is not normal, abnormal, or not good.

The stress can be in any direction, but occurs the most on the buccal of the teeth, on the cheek side. Sometimes the defect is deepened by excessive tooth brushing. Hint the misunderstanding. So when occlusal stresses occur, when you bite and something’s hitting wrong, you can actually bend the tooth. This was discovered about 30 years ago by a German dentist that used the electron microscope.

Previous to the electron microscope we could only see 1,000 power. When I used to be a hematology technician and I used to look at blood at the 1,000 power and I can see a red blood cell. That’s a 1,000 power. An electron microscope is 100,000 power. They found that if you hit the tooth wrong, if you stress it wrong, you literally can bend it and a microscopic piece of the tooth comes out and that’s what an abfraction is.

So this is a really good example of an abfraction because you have a smaller piece missing here, a large piece missing here and right in the middle there’s still tooth there and that’s very strange. So it can’t be from brushing the wrong way because if you brush the wrong way, you would just have one big defect here. So it’s very significant.

When you look at the occlusal surface, the chewing surface, and you have them bite on articulated paper you can see where it’s hitting too hard. And you see this patient has crooked teeth. So it’s the formula for having a crooked bite and teeth hitting wrong. Then when you push on the jaw . . . and many of you that are my patients remember when I have you bite and check the bite, I’ll push on your jaw when you’re moving. That replicates what you do when you clinch and grind. And you get a different marking, a much stronger marking because that’s actually what you’re doing when you clinch and grind at night or during the day.

So this is what it looks like before the induced side shift before we push hard. And you can see the areas that are hitting hard, but then when you push everything’s bigger, everything’s harder. So this is how I know where the teeth are hitting improperly and how I can adjust it.

You see the shiny surfaces and the lower tooth that’s hitting the upper has a big one, the lower tooth has a smaller one. But you see it’s a little knot just on one side not here. And that’s how you know that it’s an abfraction not tooth brush abrasion.

So this is for dentists. I prepared this for dentists. It’s easier to spot if you know what to look for. You must know how to spot the occlusal interferences and then you must learn how to correct the interferences that cause the defect. If you don’t take care of that, then the defects will come back even if you restore. So those are my words of wisdom for the day. Maybe a little technical, but no blood. Thank you for your attention. Any questions?

Man: Yes, Kathleen has a quick one.

Kathleen: Do you have time for a question? So what do you do to fix that?

Dr. Yamamoto: You have to get rid of those interferences. I reshape the teeth so when they hit they don’t bend.

Kathleen: I see.

Dr. Yamamoto: That’s the [inaudible 00:08:11].

Kathleen: So you shave off a part of the tooth above it so that it doesn’t hit?

Dr. Yamamoto: You have to shape it very precisely so that when they function it’s not in the way.

Kathleen: Interesting.

Man: Bite correction.

Dr. Yamamoto: Bite correction, you can say it. Are there any more questions? Thank you for your attention.

Dr. Mark Z. Yamamoto, Mark Yamamoto, DDS