WHAT BONDING AGENTS ARE RECOMMENDED IN THIS HANDBOOK?
On this website I am recommending a Generation V adhesive, Photobond, a Kuraray product. It is a total-etch system, (also called etch and rinse ).
The full adhesive sequence goes through the following stages
- total etch with liquid phosphoric acid 37% 5 to 10 seconds see Etching
- rinse with distilled water in a reusable 412 monoject syringe
- air dry to until no standing water is seen
- Microprime B applied, immediately blown off until no standing fluid is seen,matte surface
- Photobond A and B are mixed and applied within 15 seconds of mix
- Photobond film is blown thin until no further flow occurs and film is seen to quiver
- cure 5 to 10 seconds
Note that in crown cementation both crown and prep need not be cured before placing luting agent and seating, to prevent the cementation accident of excess bond pooling and preventing full seating.
What are its properties? See BONDING, DISCUSSION ON
- Generation V
- Total etch, no smear layer retained
- rapid overall placement time
- versatile clinical applications- indirect, direct, light- cured, not light- cured
- thin film, 5 microns
- based on MDP, a very durable monomer
- claimed 17MPa Dentin, Enamel 35 MPa
- alcohol-based
- dual cure
- free of marginal stain
- dual-cure resin-compatible
- adhesive to non-precious metals for splints see Adhesive Bridges- Anterior- Inlay-Flange
- additional primers are available for porcelain, zirconium,and for precious metals
- free of subjective application protocols-rolling,hovering,wicking,rubbing
- well proven in my practice over 35 years
- well proven in the hands of 100s of my students over a 20 year teaching career
Generation V adhesives ushered in the era of Adhesive Dentistry by establishing comfortable dentin bonding. Some Generation IV adhesives lacked adequate primers and therefore post-op sensitivity was still a clinical bugaboo, and wide-scale adoption of posterior composites was temporarily held back.
As the field of adhesives evolved, in an unfortunate turn for the profession, rather than develop better primers, manufacturers targeted acid etch of dentin as the problem. Subsequent generations – Gen VI and Gen VII were based on a retained smear layer and bonded through it, sing lower acidity formulations, which necessitated separate enamel etching, a very time- consuming and unnecessary step.This resulted in practical deficiencies, like slow application time, inconsistent etching times for both dentin and enamel, foggy ,subjective and slow application protocols and reduced adhesive durability discussed in Bonding Protocols, Discussion of
DOUBLE PRIMING AS A METHOD TO ENSURE POST-OPERATIVE COMFORT
While Generation IV or V bonding systems both contain primers, I maintain, along with many other seasoned practitioners, that an additional “Universal” primer be applied before the adhesive agent. This in effect is “double-priming” to ensure that dentin is always well-primed; the tubules are sealed, the demineralized dentinal matrix is re-hydrated, and MMPs are deactivated. See Matrix Metallopreteinases This is an essential key to post- operative comfort and durable dentin adhesion meeting the manufacturer’s claimed adhesion, and for longevity of adhesion, inactivatiing MMPs, which otherwise remain in the dentin as a “time-bomb” for promoting recurrent decay. As well, because primers closes tubules to resin components and leachates, they promote long term pulpal health in the presence of composite resins. In effect, with properly primed dentin, the pulp does not “see” that there is continuous resin.
The product chosen from the field of contenders for this function is Microprime B, by Zest Dental Products. Microprime B is formulated as follows: 59% water, NaF 1%, HEMA 35%, and 5% Benzethonium chloride.
Universal primers were reviewed by Clinician’s Report in August 2002, covering products based on chlorhexidine, glutaraldehyde, benzalkonium chloride, and benzethonium chloride.These are all mild disinfectants, and protein fixatives.They noted the least likelihood of tissue burns with Microprime B relative to glutaraldehyde formulations. Despite this, gluteraldehyde occupies the greatest market share.
Tissue burns with gluteraldehyde primers:
Gluteraldehyde formulations are the most widely used to this day. Any sloppy technique with gluteraldehyde, for example, allowing primer to pool under a cotton roll, will cause a soft tissue burn that is painful for the patient for 24 hours. Not a practice builder, my friends. Post operative pain after using Microprime B has been virtually absent in my 25 years of use.
Purchasing Microprime B in Canada:
It is available in the USA, but in Canada, due to low volume of sales, no supplier has taken out a device license with Health Canada to import it. It is perfectly legal to procure in the USA, and to use in the mouth in Canada. It can be ordered direct from Shasta Dental Supply California, 1-800-554-6394. We generally order 6 at a time for an annual supply.
Other beneficial clinical uses of Microprime B
- desensitization of exposed roots (root sensitivity)
- desensitization of crown preps after preparation.
The latter is a worthwhile benefit, because often no anesthesia is needed at crown insertion when the prep has been so treated. This is much appreciated by both dentist and patient; for the patient, because it is one less anesthetic to bear, and, for the dentist, because the patient’s occlusal proprioception is better, helping to quickly establish correct and comfortable occlusion.
HOW TO APPLY MICROPRIME B:
Once etch and rinse are complete, dry the prep to the point that no visible standing water remains in the prep. Apply Microprime B with a suitable applicator Voco #1 foam pledglet in large preps, Bendabrush in smaller preps, paper point tip in root canals and tiny preps. Immediately air-blow off the tooth until a consistent low gloss finish is seen on the tooth surface and there are no visible droplets or standing moisture.
HOW TO APPLY PHOTOBOND: STANDARD METHOD: Centrix Bendabrush
The two-part adhesive is mixed with a standard Bendabrush (Centrix) for 5 seconds and immediately applied to the tooth. If the mixed Photobond does not reach the tooth within 15 seconds, discard it and start a new mix . The volatile alcohol component of the mix is necessary to capture the water from the dentin. Air thinning of the adhesive follows, volatilizing the alcohol and entrapped water. Then cure the adhesive, 5 seconds.
SPECIAL APPLICATION DEVICES FOR ALL COMPONENTS:
Application devices for this bonding system vary according to the size of the prep.
- Large restorations need a Voco #1 foam pellet to absorb copious amounts of caries detector, etch, and primer . These pellets are carried to the tooth in cotton pliers. This method fosters rapid deployment. As well, these foam pellets can not shed“fluff” into the bonding scheme, unlike tufted applicators..
- Small restorations: Bendabrushes (regular) in for all liquids- etch, prime and bond (rather than just the bond. )When using brushes, differing colors of brushes are routinely used to prevent inadvertent re-use of an incorrect brush for a step. Again, these are bristle brushes with out the possibility of shedding fluff into the preparation.
- Root canals and very small preps:#60 paper points are used in canals being prepared for posting and very small preps with limited dentin exposure such as FISSUROTOMY
THE PRIMER:
Microprime B is applied with the Voco#1 pledglet and immediately blown free with triple syringe and HVE until a consistent low gloss finish is seen on the tooth surface and there are no visible droplets or standing moisture. The manufacturer recommends up to 20 seconds application time, but the author has 25 years of 100% satisfaction without this length of time.
TOTAL TIME TO APPLY A BONDING FILM WITH THIS SYSTEM
The total time to apply a cured bonding film is approximately 35 seconds, one of the most rapid application sequences there is in dentistry.
TABLE 2: SYNOPSIS OF BONDING METHOD
Note that when only Bendabrushes are used as the applying device, different colors are regularly selected so there can be no confusion if one re-uses a brush.
Also, as efficiency measure, the yellow bottle component (bonding agent catalyst) can be dispensed at the outset of the procedure, ahead of the green bottle component( bonding agent universal) This is a time-saver and possible is because this thick component is not volatile. The green, containing the alcohol, is very volatile, as noted above. Also, as in most dropper systems, a consistent tilt to each bottle must be found to dispense equal sized drops efficiently. However, this is not a integrity issue, rather a time- saving issue, because there seems to be a wide and forgiving safety margin in proportioning without any clinical downside.
| AGENT | APPLICATION TIME AND DEVICES | REMOVE/THIN | DRY | CRITERIA |
| 37% PHOSPHORIC
ACID ETCH |
10-15 SECONDS VOCO #1 PELLET BENDABRUSH (REGULAR)(RED) #60 PAPER POINT |
DISTILLED WATER IN A 412 MONOJECT SYRINGE
|
3-5 SECS RINSE | LIGHTLY FROSTY
ENAMEL |
| PRIME | VOCO PELLET#1
OR BENDABRUSH (REGULAR) GREEN NO DURATION REQ’D |
5 SECONDS | 5 SECONDS | SLIGHTLY GLOSSY |
| PHOTOBOND | 5 SEC MIX TWO COMPONENTS IN WELL. APPLY BENDABRUSH (REGULAR) YELLOW | 3-5 SECS
AIR BLAST |
3-5 SECS
AIR BLAST |
BLOW UNTIL NO FURTHER FLOW OCCURS AND THE SURFACE QUIVERS |
DEMONSTRATED EFFECTIVENESS
What proof is there of the effectiveness of these adhesives? As stated at the outset, manufacturers need not prove very much to the regulators. What testing we see is usually proprietary, thermocycling in distilled water to 37 degrees C. is only a crude approximation of clinical service. It is probably only indicative of aqueous lysis.
However, some studies show some adhesives retain less than 20% of initial bond strength, and some are so weak that sample disintegrated before they could be tested.
Other bonds fare well and show good clinical performance in 2 and 5-year tests by The Dental Advisor, so there appears to be a broad range of effectiveness. Heaven help your practice if you are using a bond that is a marketing success but a clinical failure.
It would benefit the profession greatly if an accelerated aging test were developed that exposed bonding agents to a wide spectrum of challenges beyond thermocycling in 37-degree distilled water. If the excellent minds of the research community were applied to this issue, something could be developed. There appears to be a lack of will to do so. So, the manufacturers currently run the show, much to their marketing advantage and much to the detriment of the patient, practitioner, and profession.
What proof can I offer for Photobond? Its proof is clinical. I have 35 years of successful restorations behind me – no sensitivity, no lost restorations, no marginal stain. Study club members who I have taught over a 20 year time frame have had the same outcome. It is not personal.
This can be challenged scientifically, but it cannot be denied.
Objectively, the monomer of Photobond is based on MDP. Its formulation is like Panavia F2.0 without the particulate of that product. F2.0 one of the least soluble resin cements with an unparalleled clinical record. In fact, with a 25-year track record. Panavia F2,0 and its predecessors in the powder/liquid mixing format are one of the unequivocal success stories of the adhesive era.
ARE THERE NEWER MDP BONDING SYSTEMS THAT CAN BE RECOMMENDED?
There are many new Generation VII adhesives utilizing MDP. Sadly, none have effective dual-cure capacity. They claim so, but independent testing by Reality Research does not corroborate this. Don’t want to believe this? Subscribe and read for yourself. Some products demonstrate dentin bond strengths in the realm of 8MPa, far short of a clinically adequate threshold, which has been determined as 17MPa.
So, we wait in the wings until they get their act together, and slowly fume that we dentists are not informed, and the public is duly deprived of objective proof of success. Unfortunately, nobody can do any better in the current information vacuum of our profession.