When analyzing bone regeneration one must consider certain facts-
1. 5 year followup of furcation procedures for bone regeneration showed significant failure rate occurring. Vertical regeneration occurred but not regeneration to the furcation itself.
2. I have had several radiographic successes only to open up the area and find failure.
3. In 1980 I did a video with Dr. D. Walter Cohen and Dr. Burton Langer on bone regeneration using Hydroxyappetite. I showed extremely succesful radiographs only to do re-entry and find fibrous encapsulation of material-no regeneration though no probing or bleeding upon probing.
4. Root irregularities are more important than we realize for success of regeneration procedures.
5. Kelly asked why open up cases? Not laser technique. That will really be the only way to determine success. X-rays can always be misleading.
6. I am so impressed with Bob’s material and am sure regeneration will be found in re-entry.
7. Personally I think if Ron reentered his case he would not be so happy. As I said before, I think the angulation of the x-ray is very misleading.
This is not a negative take on what I see-this is an objective statement, based on what we all know to be true about x-rays-they are misleading. Visual observation solves the x-ray problem-no one  can deny what they see.
Root form is critical!
Danny

(Edited by Dan Melker at 8:52 pm on June 6, 2004)

Hi Ken,

Thanks for the email!

Here’s part of the answer to your question in a study done by Dr. David Harris:

0855 Ablation of Porphyromonas gingivalis in vitro with Pulsed Dental Lasers
D.M. HARRIS, University of California, San Francisco, USA

Abstract  

Both pulsed Nd:YAG (1064nm)and continuous diode (810nm) dental lasers are in current use for treatment of periodontitis. It has been shown that laser treatment kills pathogenic bacteria (laser antisepsis), but a quantitative method for determining clinical dosimetry does not exist.

Objective: The purpose of this study was to develop a method to quantify the efficacy of ablation of Porphyromonas gingivalis (Pg) in vitro for two different lasers.

Methods: The ablation thresholds for the two lasers were compared in the following manner. The energy density was measured as a function of distance from the output of the fiber-optic delivery system. Pg cultures were grown on blood agar plates under standard anaerobic conditions. Blood agar provides an approximation of gingival tissue for the wavelengths tested in having hemoglobin as a primary absorber. Single pulses of laser energy were delivered to Pg colonies and the energy density was increased until the appearance of a small plume was observed coincident with a laser pulse. The energy density at this point defines the ablation threshhold.

Results: Ablation thresholds to a single pulse were determined for both Pg and for blood agar alone. The large difference in ablation thresholds between the pigmented pathogen and the host matrix for pulsed-Nd:YAG represented a significant therapeutic ratio and Pg was ablated without visible effect on the blood agar. At threshold the 810-nm diode laser destroyed both the pathogen and the gel.

Conclusion: Clinically, the pulsed Nd:YAG may selectively destroyed pigmented pathogens leaving the surrounding tissue intact. The 810-nm diode laser may not demonstrate this selectivity due to its greater absorption by hemoglobin.

<a href="http://iadr.confex.com/iadr/2003SanAnton/techprogram/abstract_27983.htm

Millennium” target=”_blank”>http://iadr.confex.com/iadr&#8230;.lennium did not fund this study.

The reason for the difference in tissue effects and selectivity has to do with peak powers not wavelength.

The free-running nature of pulsed Nd:YAGs is what delivers near-infrared (N-IR) energy to the pigmented pathogens with enough intensity to penetrate the mass of granulation tissue and denature sensitive proteins while those not as highly absorbed by the N-IR wavelength (which is still a factor) are left viable.

If one could pulse a N-IR diode in the millionths of a second, and allow for high peak powers and long thermal relaxation times, then it ought to work as well.

Does that help?

Bob

Hi Ken,

Since I have never heard of or seen a FR pulsed diode, I can’t answer as to whether there would be more or less absorbtion in hemoglobin as to make much difference.

There is no tissue penetration into perio pocket tissues. That is the point of Harris’ study. CW diodes only have a surface effect as they are most often used in a “hot tip” or “activated” or “conditioned” fiber mode.

FRP Nd:YAGs are never used in an activated or conditioned mode in the perio pocket. That allows for the beam to transmitt into the tissues while keeping intensity and selectivity at depth.

I have a great demo/parlor trick for this. I can vaporize completely the black ink through an anesthetic carpule filled with water/anesthetic. When a diode is used, the plastic wrapper ignites on fire…..

Bob

Morning Danny,

No, there are other FRP Nd:YAGs out there that have “long” pulse durations and can create the desired hemostatic effect.

Lares Research is presently the only other company in the USA that has a “short” PD of 150 usec and a single “long” pulse duration of 635 usec that Del and I disclosed to them when they made their laser for MDT to resell.  They use a different nomenclature now at our insistance of 110 and 280 or something so as not to confuse their parameters with ours.  (We think our confidentiality agreement they signed prevents their resale of a “dual pulse” to the dental market, but that’s a lawsuit for another time).

The PerioLase MVP-7 has 100, 150, 250, 350, 450, 550, and 650 usec pulse durations.

100 is good for cutting with minimal thermal injury (due to short “on” time).  Useless for hemostasis.  Highest peak powers = deepest penetration and bug kill rates.

150 is good for cutting with a little hemostasis.  A nice “tweener” for most clinical situations.

250 – 650 is all about using the appropriate amount of PD to control the hemostatic repsonse depending on the clinical situation, and that allows the clincian to select the rate of speed they want to move.  Nice to have a laser that is responsive to the operator and not the other way around.

At 650 one needs to move pretty fast or have a massive bleeder.  At 350 one can move the fiber less rapidly w/o causing a problem.

700 usec is the threshold for human tissue and thermal relaxation (aka thermal relaxation constant).

Hence the reason we backed away from a laser with 700 or more.  We used a medical laser with 700 usec and up to 1000 usec and 700 and above is just to hard to use and avoid the damaging effects to collateral tissues.:o  Sure it controls bleeding!  But the thermal injury potential is just to great and happens quickly for even a skilled FRP Nd:YAG laser operator.

So unless the thermal properties of human tissues change anytime soon, the Periolase MVP-7 operating parameters will not be changing!  As a result there are no plans to “improve” on the PerioLase.  Maybe a color screen someday???

There are other FP Nd:YAGs that have “long” pulse durations, but they are not available in the USA–like the Fotona Fidelis.  I think they have 150, 350 and 1000 usec.  Interesting selection–no doubt made by an engineer–but they don’t make a lot of clinical sense to me.  If I had only 3 PDs to choose from, those would not be the ones.

The question becomes which PD to use under what conditions, how, and at what power and repetition rates–hence the emphasis with MDT on clinical training (not a CD-ROM with “borrowed” and incomplete info).  There are few clincians with experience with various long PDs in tissue with Nd:YAG–and most (in fact all in the USA) are using a laser parameters of our design and configuration.

I spoke with C.C. Rice from Texas yesterday.  He’s a long time single pulse (100usec) Nd:YAG user.  Been using the PerioLase MVP-7 for about 3 months now.  He just laughed at the ease of hemorrhage control compared to his single pulse device.  He was calling the Periolase a “turbo” “four-wheel drive” laser for it ability to adjust to the different clinical conditions.  I thought that was a pretty good description.

Thanks for the great question!

Bob

I’m confused by this statement and need clarification.

Do you mean?:

1) In most instances, if the practitioner is using the Periolase at 650 usec PD he/she needs to move the fiber tip rapidly to avoid tissue damage(because the laser is firing for a long time at 650 usec)

2) However, the 650 usec setting can also be used in a focused state when the practitioner has a large blood vessel with difficult to control hemorrhage

Thanks,

Al

I’ve been told the diode fiber should be placed 1mm shorter than the perio pocket.

True

On the other hand, I think Rusty Schaeffer told me with the LPT protocol the fiber should be placed to the full depth of the periodontal pocket???

True

Does it relate to activated vs. inactivated tips or pulsed, high-peak powers attainable with the Nd:YAG

I think different objectives, part of the FRVPnd:YAGg objective is to gain access, remove debris,then stimulate osteoblasts and create a clot allowing the body to heal. The diode objective is to remove inflamed tissue and prevent epithelial downgrowth.

If the doctor has to re-measure each perio pocket and then re-set his fiber length with a diode, isn’t that a real PIA(Pain in the A&#36&#36)?

IMO Yes

Who actually does this and how practical is it considering diode laser handpiece design?  We should have fibers that are marked in 1mm increments!!!  But the laser would probably focus on any pigmented markings.

Unless Tx protocols have changed, don’t forget each subsequent Tx is 1 mm shorter so your 6mm pocket(below) will require 3 visits

So on number four I have a mesio-buccal 4mm and on the disto-buccal I have a 6mm.  I’m actually going to stop and extend my diode fiber from 3 to 5mm for the DB pocket??  This seems silly and not clinically reasonable.

Agreed