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lunkenheimer
04-22-2009, 11:26 PM
I had an interesting conversation with my dentist today. At one point I asked him if he had ever used the old belt-drive dental drills (since I have seen these for sale in antique malls, I was curious). He replied "Never in a mouth, they're dangerous". Well, I assumed he was referring to the belt drive (usually a spring belt) but then he explained "it only takes 8* temperature rise to kill a tooth. There's no coolant with the old drills."

Now this is a tenuous connection to machining but I thought it was interesting to consider that:
1. Even a small output machining device can put enough heat into the work to damage it.
2. The air, water spray, and dribbling water from current dental handpieces is enough to make a critical difference. (I always wondered why the drills etc. made my mouth cold)

We're not likely to be doing such critical work, but it never hurts to know about extreme situations... maybe if working with ivory, for example. This was just interesting to me and I thought I would share.

Frank Ford
04-23-2009, 12:35 AM
Eight degrees to kill a tooth? What's with that guy? My toothies are still solid and healthy. I have a mouthful of filings made with silver amalgam (yes!) done a long time ago (I'm 65 now) and drilled with the old belt drive system, sans coolant. Gimme a break.

tyrone shewlaces
04-23-2009, 12:52 AM
I'm pretty sure that my morning coffee is at least 300 degrees warmer than the inside of my mouth. The first sip is anyways.

Hasn't killed a tooth yet, and so far the blisters have healed regularly too.


mmmmm..... cooffffeeeeeee......

TGTool
04-23-2009, 12:56 AM
Eight degrees to kill a tooth? What's with that guy? My toothies are still solid and healthy. I have a mouthful of filings made with silver amalgam (yes!) done a long time ago (I'm 65 now) and drilled with the old belt drive system, sans coolant. Gimme a break.

How long has it been since those teeth waved a hand, jumped up and down, moved around or showed that they ARE still alive and kicking? :D

gearedloco
04-23-2009, 01:02 AM
Eight degrees to kill a tooth? What's with that guy? My toothies are still solid and healthy. I have a mouthful of filings made with silver amalgam (yes!) done a long time ago (I'm 65 now) and drilled with the old belt drive system, sans coolant. Gimme a break.

I suspect he's talking about what can happen after passing through the enamel
and getting to the stuff inside. But it's only a guess.

Those new-fangled ultrasonic scalers are what gets to me. I think I now know what water-boarding must feel like.:eek: When I had my teeth cleaned the other day I mentioned it to the hygienist so she just went with the old reliable hand scraper. She must have known what she was doing as it wasn't all that uncomfortable.

J Tiers
04-23-2009, 01:10 AM
He might be closer to correct, although obviously 8 deg is low......

My dentist, who is generally great, is heavy-handed with the drill when doing a filling. I generally have a sensitive tooth for way too long after he has been at work..... so I try to keep him unemployed as far as drilling is concerned.

Paul Alciatore
04-23-2009, 01:48 AM
He might be closer to correct, although obviously 8 deg is low......

My dentist, who is generally great, is heavy-handed with the drill when doing a filling. I generally have a sensitive tooth for way too long after he has been at work..... so I try to keep him unemployed as far as drilling is concerned.

Get a new dentist.

J Tiers
04-23-2009, 02:23 AM
Get a new dentist.


Not one chance of that.

He put on a couple crowns and there was not a speck of trouble, although that is a LOT more work on the tooth. An prior filings had no such issues, this one was down the side of the tooth.

No, he gets a "pass" on the filling, it may not have been all his fault anyway.

hwingo
04-23-2009, 04:29 AM
Eight degrees! I think not. Our high speed hand-pieces turn in excess of 600,000 RPM where as our slow speed hand-pieces turn around 38,000 RPM. Burs used in high-speed hand-pieces, being fabricated of carbide, generate a great deal of heat, and so much so that should the bur dull during tooth preparation (which often happens) fire can be seen deep in the cavity preparation if coolant is not used. Smell, often associated with burning hair or flesh, is the result of heat generated by the bur as organic matter is being "cooked" by a heated bur. Obviously, water coolant significantly reduces heat making the cutting process kinder to tooth structure.

Even with amelogenesis imperfecta, (a condition often leaving the surfaces of teeth void of enamel with dentin directly exposed to the environment), teeth do not die when hot foods and liquids are ingested. Similarly, cold can be a serious stimulus but teeth are designed to handle that extreme as well. They are marvelous little "tools" capable of surviving great punishment. Even if a tooth is "fired up" in the absence of coolant, the tooth will likely survive albeit thermally sensitive for 6 to 8 weeks.

The greatest danger of "killing teeth" resides with rubber-cup cleanings by untrained "assistants". This is the reason that most states in the US require licensed hygienist to perform cleanings ..... not dental assistants. Even at low speeds, rubber cups prophys produce very high temperatures over a far greater surface area making death to teeth via cleanings more likely.

For informational purposes, as surface area involvement increases, so does the likelihood of thermal sensitivity. Crown preparations can be used as a good example of great surface area involvement leading to sensitivity and even death of a tooth. Depth too can lend a twist to thermal sensitivity. Individuality also plays a part. Not all teeth are created equally. Some individuals feel NO PAIN when threated without anesthesia whereas others may experience *PAIN*.

Just my two cents.

Harold

A.K. Boomer
04-23-2009, 10:02 AM
And Hwingo sets it all straight --- thats what I like about this site, you never know what your going to learn:) 600,000 rpm's is allot of reps, now if you couple that with 850 ft.pounds of torque you really got something...

Evan
04-23-2009, 10:28 AM
On a side note, the next time you are at the dentist ask them to save you the carbide burrs. Just because they are too dull for dental work doesn't mean they are too dull for engraving and other small jobs. They are usually just tossed and most dentists will save them for you, with perhaps the exception of Harold who I bet saves them for himself. :D

oldtiffie
04-23-2009, 10:45 AM
Aren't used burrs supposed to be disposed of as for "sharps" and anything blood-stained or with body parts or fluids in or on them? ie into the "Yellow" hazardous wastes bin/box/bottle etc. and then destroyed in a super hot furnace?

Evan
04-23-2009, 12:18 PM
A quick soak in anhydrous ethanol will kill everything, even prions.

snowman
04-23-2009, 01:55 PM
The temperature increase kills the root of the tooth, not the enamel.

Ultrasonic scalers can do the same thing, if the user is not skilled. If you work on one tooth too long, it can heat the tooth and damage it.

lunkenheimer
04-24-2009, 11:49 PM
I myself wondered about the 8 degrees that my dentist mentioned. But, his mouth wasn't full of hardware while mine was. So, I couldn't have a full discussion on this topic...

In any case I thought this was an example of 1. the heat generation that can be caused by a fairly simple tool and 2. an interesting example of how this heat can be dealt with (the water spray mentioned earlier)

FWIW, I have most procedures done without novocaine since I find that the pain of a bitten cheek is more aggravating than the pain of a drilled tooth. So, I notice when things get warm. It doesn't take much heat for me to feel it...

My dentist generally uses the latest non-mechanical decay removal techniques, though, so this is not as masochistic as it might seem.

Lastly, he did refer to Bill Cosby's dentist visit skit and the 'smoke was coming out of my mouth' lines, so I tend to think he is not just a theorist....

dneufell
04-25-2009, 01:29 AM
cool dentist story time.....ultra sonic scalers......the chick(dental hygenist)
tell me about the new "toy" she is going to use on me. I say fine, lets do it.
Every time she uses it on my teeth i am getting a shock. I tuff it out for a while and then i tell her it feels like the machine is not grounded. She looks
at me weird like and then tells the Dr. He comes in and checks it out and almost s***s........Dean

ps...no charge visit
next free cleaning
1 free crown

.RC.
04-25-2009, 02:32 AM
The dentist I go to has a CNC machine for making crowns while you wait...Last time I went in for a check up it was working making up a new tooth for the patient before me.. I did not get to see it but it was quite noisy...

hwingo
04-25-2009, 12:07 PM
Aren't used burrs supposed to be disposed of as for "sharps" and anything blood-stained or with body parts or fluids in or on them? ie into the "Yellow" hazardous wastes bin/box/bottle etc. and then destroyed in a super hot furnace?

Hi Tiffie,

Ordinarily, by today's standards, "sharps" are manufactured as disposable items. Some items, not designed as "disposables" but subjected to bio-hazard materials, e.g. diamonds and composite finishing burs, may be tossed primarily due to lower production cost as compared to production cost only 10 years ago. However, "use & toss" can be expensive driving up treatment-cost. A quality diamond bur may cost upward of $10 to $15.00 depending on geographical location. However, such non-disposable items as mentioned can be, and often are autoclaved or gas sterilized and re-used. Heat sterilization quickly dulls carbide and SS burs but it is permissible to sterilize burs for re-use. Many of our instruments are very sharp ...... and expensive too. I perform surgery many times daily. My surgical instruments are "in the thick of battle". They are immersed in blood, guts & gore. Though sharp, with a ubiquitous potential for percutaneous injuries to patients and members of my surgical team, these heavily soiled and bio-ladened instruments are subjected to rigorous cleaning standards after use and prior to sterilization. When dealing with oral and maxillofacial surgery, the very nature of the oral environment predisposes our sterilization-chain to weaknesses. The mouth is not sterile nor can it be made sterile in a *living patient*. Dental explorers, as one example, are very sharp and defined as "sharps" but are not thrown away, rather, properly cleaned and sterilized. Conversely, a surgical drill, or even the conventional high and low speed dental drills, are not sharp however they are being constantly immersed in body parts and body fluids. The inner workings of these "drills" (chuck and bearings) are not impervious to pathogens or bio-burden. Consequently, today's "drills" are designed to be either disassembled and physically and mechanically cleaned, as is the case of slow-speed handpieces, or afforded the ability, in the case of high speed handpieces, of being subjected to stringent ultra-sonic mechanical "cleanings" (using strong organic digestive detergents and disinfectants) prior to sterilization. Mouth mirrors are forever being plunged into "goo" and frequently in juxtaposition with tissue (healthy and diseased). Disposable exam mirrors are being used more frequently but reflective surfaces of these mirrors are poor quality and unsatisfactory for surgery. We really need to see what we are cutting thus we use conventional mirrors when required.

Often, the informed layman becomes confused. *Their definition* of sharps and bio-waste may be skewed. Dental treatment and/or surgery would be cost prohibitive if everything sharp or soiled were required to be thrown away. A surgical handpiece may cost upward of $5000.00 (with no mention of connecting hoses or electrical leads). Conventional high and low-speed handpieces cost on the order of $1000.00 to $2000.00 depending on geographic location. Pressure cuffs, electrical leads, monitors, etc. are subjected to aerosols generated by rotary instruments hence contamination. All these items carry a hefty price.

Naturally, I could carry this discussion from the sublime to ridiculous pointing out, for example, stretchers are frequently soiled with feces, urine, vomitus, and blood, with no less emphasis on an entire list of undesirable sources of contamination. Stretchers, operating room tables, flooring, surgical lights, walls, ceilings, doors and such are virtually impossible to *sterilize* but they can be *disinfected*. I suppose disposable Operating Rooms are a possibility but at what cost. Erecting a disposable operating room, while maintaining sterility, would be a daunting task and a logistical nightmare without mention of cost to the patient.

As long as invasive procedures are performed, nosocomial infections are a reality with which we must contend.

Just thought I would put in my two cents.

Harold

Guido
04-25-2009, 10:12 PM
Recently finished a one tooth scenio. Visited with the DDS and compared his definitions and reference of same, to machine talk:

Morse taper on implant, and miniature racheting torque wrench to apply 13 centermeter-Newtons of torque to set implant in jawbone.

Not too shocking, but fees tore the heck out of 3G's.

G

hwingo
04-25-2009, 11:11 PM
Ordinarily, it takes 35-40 Newton Centimeters of torque to seat an implant. Thirtyfive NC is minimally optimal whereas 40 is the upper limit. Thirteen is quite light. This means the implant is virtually spinning in the osteotomy and this is an undesirable situation. For oseointegration to occur and not a fibrous union (which will certainly lead to failure in nearly all cases) a far tighter interface is need for HA coated implants to osseointegrate. Even if the implant body is buried under closed tissue for 12 to 13 weeks, depending on bone quality, the implant might still fail and be rejected before the abutment is ever placed.

Harold

oldtiffie
04-25-2009, 11:51 PM
Thanks Harold.

I was aware of most of that as in one of my previous incarnations I was the Facility Officer in a large military establishment. My work was largely to do with - among other things - the maintenance and construction/installation of "Hospital" (including "Medical" and "Dental") facilities - by specialist Contractors. I am aware of the sterile requirements of spaces and objects as well the the means of achieving and maintaining them - autoclaves (all types) included.

I am aware that you have very comprehensive as well as intimate knowledge of that equipment and procedures including sterilization and disposal - as well as the "cost" rationale'.

I am not sure that others are.

For me, if I wanted a sterile burr, I would be damn sure that it had either passed through a sterilisation treatment if used or if new, that it was in a sterile environment in a certified packing that was still within its "use by date".

Incidental, some of the best and most comprehensive Carpenters and Fitters tool kits I ever saw were in the Operating Theatre sterile confines or in autoclaves that needed to be "got going" (again). Same applies to "Dental". Some of the "Tools" in the medical/dental museums etc. would make some quite ill just thinking about it!!

The new Hospital Dental section had lead-lining on the wall-board and doors. I was told that it was necessary to contain the "radiation" (X-Ray etc.) within the Surgeries (from those in the waiting rooms and corridors). Needless to say it didn't take long for "Radiation" to be supplanted by "noise/screams".

Needless to say I had no problem getting "sharps" (mainly scalpels and blades - and burrs) for my "use" still in the original (and "in date") wrappings etc.

Further, as I was told and found out very early in life, the true-ism that it is more often than not that it is the blunt rather than the sharp knife that does the damage (improper use) - I don't use blunt tools - "burrs" included.

Perhaps the previous paragraph related more to the "dull" user than the dull tool/cutter/burr etc.

None of my hand cutting tools are put away "blunt" as they "stay out" until I sharpen them. That way I always have a sharp tool when I pick it from its stowage.

I'd like to think that I am as sharp (well, often enough anyway) as my tools.

As for burrs, I just go and buy a $50 pack of TC burrs of various kinds from a local tool supplier. As soon as I sense the tool (usually a die-grinder) has to work harder the burr comes out and goes straight into the garbage bin in the shop.

mwechtal
04-26-2009, 12:13 AM
Hwingo,
As someone that is going to recieve an implant in less than a week, I find your posts on this subject very informative.

However, referring to the quote below, that indicates to me that your incision may have gone astray if guts are involved. :D I prefer an abdominal surgeon for surgery in that area!

They are immersed in blood, guts & gore.

oldtiffie
04-26-2009, 01:15 AM
Mike,

just make sure that the person doing your "insert" is not a Veterinary Surgeon (aka "Vet").

After reading that post of yours, that procedure that Harold was talking about does seem very similar to an artificial insemination (AI) of a cow!! - with cow with its head in a bail - and more than a bit apprehensive - AI person (a "Vet" - usually but not always) with shirt sleeve rolled up to the arm-pit and full arms-length gloves on (sometimes no gloves - or clothes above the waist), cow bellowing like hell, then "whack" - right up to the shoulder and job done.

Cow, which had the job done, was not all that unhappy afterward, but the bull which was tethered and looking on was not pleased at all - and let us all know it!!!

hwingo
04-26-2009, 02:28 AM
Well CRAP! I inadvertently discontinued my instant email notification for this thread so I am writing this to get "re-enrolled" in the thread. Duh!:o

Harold

oldtiffie
04-26-2009, 04:30 AM
Harold,

if there is any more (or not too much) "blood and guts and gore" and hacking and stabbing, George B might transfer it to the "Pirate" thread.

From my reading of other threads, some here are as tight as a fish's ar$e as regards spending money and getting a $ out of 'em would be worse than pulling tooth a tooth - or three!! - (NOT "wisdom" teeth as they are long gone). I'd suggest a good dose of root canal work TO and not BY them if for no other reason than to knock off the snots 'n' burrs - and sundry rough edges!

Incidentally, in that Medical/Dental complex I spoke of earlier were the two best golfing teams in the Establishment - first the Dentists and next the Doctors. It seemed that is was the same in some of the other Establishments too.