Report on Use of a Modified “Colonna” Technique for PFM Crown Preparation using an Erbium Laser:

70 yo female presented today with lingual cusps fractured off tooth #19.  MOD amalgam and buccal cusps intact.  Profound anesthesia was established. Bien Aire electric handpiece used to rapidly remove the amalgam and old base under 2.5X magnification.

An Erbium(Er,Cr:YSGG) laser was used for the occlusal, axial and marginal preparation at 4W.  A shoulder margin was prepared along the entire periphery of the preparation.  Speed of preparation was rapid using the laser – approximately four minutes.

With the electric handpiece, a tapered round ended diamond bur was used to smooth the laser prep along the occlusal, axial and marginal surfaces.  Smoothing of the prep required approximately 60 seconds.  The laser was then used at 1.25 W to create a gingival “trough” and clear delineation of the margins.

Patient reported that she liked the laser and preferred the sound and feel to the high speed handpiece.  

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Obviously, what I’m reporting is greatly modified over what Mark is doing.  My point is, after reading his article I was able to successfully incorporate some of his technique into a crown prep during my first attempt.  With time, experience and patience I hope to incorporate more of what Mark has suggested into my practice.

Comments, criticisms and “flames” are welcome.

Al

Glenn,
I don’t remember where I heard or read this (Graeme Milicich perhaps-I’ll check my cd’s at the office)and I’m not being critical in the least, but on lased teeth I remember something about caries indicator dye giving false positives on lased teeth.
I’ve stayed away from doing this- anyone else familiar with this line of thinking?
Love the pictures, wish I had a scope to see like that!
Thanks to all you guys for the posts-I’m learning alot

Mark:

My modified “Colonna” technique went well.  In Florida, we treat an elderly population so the reason we place crowns is because of failed amalgams.  The benefit to the patient was a reduction of use of the high speed handpiece and no use of the slow speed.

I did feel it was important to smooth the preparation with the diamond bur in the electric handpiece.  Just didn’t feel comfortable with the roughness of the prep after usage of the laser.  However, I was surprised that I was able to use the laser for the gross reduction and also to create a nice shoulder margin around the prep.

Mark, I’m impressed that there are still a few “old farts” out there who place gold crowns, 3/4 gold crowns and gold onlays.  Personally, I’m sick and tired of doctors who promote “metal-free” dentistry.  As a frame of reference, I’m 41 years old and graduated from dental school in 1989.  My posterior mandible is restored with gold onlays and I have a MO gold inlay on tooth #3.

Al

Hi Glenn,

Heck yeah!!  Pulsed Nd:YAG cuts dentin very well, as well as removes caries very well and very selectively–leaving behind healthy enamel and dentin.  It can act as a very good “caries detector” that way.  It is a good dentin bacterial decontamonator and desensitiser as well.

As few examples:

Contact pulsed Nd:YAG ablation of human dentin: ablation rates and tissue effects

Harris, David M., Univ. of Illinois College of Dentistry; Yessik, Michael J., Incisive Technologies, Inc.
Publication:Proc. SPIE Vol. 2128, p. 409-415, Laser Surgery: Advanced Characterization, Therapeutics, and Systems IV, R. Rox Anderson; Ed.
Publication Date:9/1994

Abstract:

Dentin from freshly extracted human teeth was exposed to flashlamp pumped Nd:YAG pulses (100 microsecond(s) duration, 50 – 200 mJ/pulse) delivered through a flat cut fiberoptic in contact with the dentin surface. Ablation depth and volume were measured optically and confirmed with electron microscope morphometrics. Ablation depth increased with force applied at the fiber tip up to 5 – 10 g. Above this ablation depths were insensitive to applied force. Craters made in dental stone were deeper and narrower than those made in normal dentin. Ablation depths per pulse and volumes per pulse decrease as the number of pulses increase. This is more prominent for 200 mJ pulses. At 60 mJ the ablation depths are the same from 10 to 100 Hz repetition rates, although qualitative changes (collateral damage) are greater at higher repetition rates. A progressive increase in collateral damage is seen from the 1st through the 200th pulse.

http://spie.org/scripts/abstract.pl?bibcode=1994SPIE%2e2128%2e%2e409H&db_key=INST&qs=spie&s_type=paper

Histologic and SEM evaluation of caries removal and restoration in enamel and dentin using a pulsed fiber optic delivered Nd:YAG laser

White, Joel M., Goodis, Harold E., Kudler, Joel J., Eakle, W. S., Univ. of California/San Francisco School of Dentistry; Neev, Joseph, Beckman Laser Institute and Medical Clinic
Publication:Proc. SPIE Vol. 2128, p. 439-452, Laser Surgery: Advanced Characterization, Therapeutics, and Systems IV, R. Rox Anderson; Ed.
Publication Date:9/1994

Abstract:

The pulsed Nd:YAG laser has been proposed as an alternative to the dental handpiece for caries removal in enamel and dentin. The purpose of this study was to systematically evaluate, in vitro, the process of caries removal and restoration in enamel and dentin. The effectiveness of this device was investigated utilizing scanning electron microscopy to determine the behavior of dentin after laser treatment of artificially created carious lesions in dentin. Histologic sections of extracted teeth after laser treatment and restoration demonstrated successful caries removal and restoration using the pulsed fiber optic delivered Nd:YAG laser as compared to both high and low speed rotary instrumentation. The adjacent enamel and dentin were unaffected by the laser irradiation although slight carbonization was seen on the dentin surface. Thermocouples placed in the pulp chamber during caries removal confirmed previous studies that showed laser parameters up to 1 W and 10 Hz being the same as conventional caries removal in the amount of heat generated which reaches the pulp. The addition of air/water coolant decreased pulpal temperature.

<a href="http://spie.org/scripts/abstract.pl?bibcode=1994SPIE%2e2128%2e%2e439W&db_key=INST&qs=spie&s_type=paper

Bacterial” target=”_blank”>http://spie.org/scripts&#8230;.cterial reduction and dentin microhardness after treatment by a pulsed fiber optic delivered Nd:YAG laser

Goodis, Harold E., White, Joel M., Marshall, Sally J., Marshall, Grayson W., Univ. of California/San Francisco School of Dentistry
Publication:Proc. SPIE Vol. 2128, p. 431-438, Laser Surgery: Advanced Characterization, Therapeutics, and Systems IV, R. Rox Anderson; Ed.
Publication Date:9/1994

Abstract:

The purpose of this study was to determine the microhardness and extent of bacterial reduction of contaminated dentin following pulsed fiber optic delivered Nd:YAG laser exposure. Knoop hardness was determined before and after laser exposures from 0.3 to 3.0 W and repetition rates of 10 to 30 Hz. Half the sections were covered with an organic black pigment before laser exposure to evaluate the use of the pigment as an initiator to increase laser absorbance on the surface. Repeated measures design was employed to determine the microhardness of cut and polished dentin sections. Additional dentin sections were sterilized by gamma irradiation and then inoculated with B. subtilis, E. coli or B. stearothermophilus. The contaminated sections were exposed to contact delivered Nd:YAG laser. Cultures were obtained from the dentin surfaces and the colony forming units counted. Increased microhardness was found for all laser treatments above the physical modification. Bacterial reduction was obtained but complete sterilization was not.

http://spie.org/scripts/abstract.pl?bibcode=1994SPIE%2e2128%2e%2e431G&db_key=INST&qs=spie&s_type=paper