by Gordon J. Christensen, DDS, MSD, PhD
In this monthly feature, Dr. Gordon Christensen addresses the most frequently asked questions from Dental Economics readers. If you would like to submit a question to Dr. Christensen, please send an email to [email protected].
Question ...
I have been experiencing symptoms that I believe are related to chemical disinfectants in the office. I have experienced progressively worsening headaches, forehead and cheek burning and itching (rash and acne), numbness of cheeks, pain to facial muscles, dizziness, and coughing. We use the wipe technique with disinfectants — Birex. I feel better by Sunday mornings, but I am worse again after working Monday. Please help.
Answer from Dr. Christensen ...
Your question is not uncommon. It is logical to assume that if a disinfectant kills microbes, it is likely to be a problem for humans as well. However, as you know, there are hundreds of chemicals in the dental office, any one of which may be causing your symptoms. Therefore, it is difficult to know if the problems you described are related to the disinfectant you use. I have discussed your question with Dr. Rella Christensen, who is an expert in your area of concern, and we have the following suggestions.
Assuming the health challenges you stated are related to your disinfectant, one way to test that hypothesis is to change the chemical category of your disinfectant. The major active ingredients of the disinfectant you are using are phenolics (0.03 percent ortho-phenylphenol and 0.03 percent para-tertiary-amylphenol). There is a possibility you are sensitive to phenolics. Another reason to change products is that the disinfectant you are using does not provide the broad-spectrum kill of organisms that is available with several other disinfectants.
We suggest that you change to Lysol Brand II Disinfectant Spray, which has ethyl alcohol as its active ingredient (79 percent ethanol and 0.1 percent dimethyl benzyl ammonium saccharinate). It is readily available in grocery stores.
Some practitioners use Lysol Spray incorrectly. This disinfectant should not be sprayed directly on countertops or other objects, because potentially harmful aerosols are created, which can be irritating to the respiratory system. Lysol Spray is packaged in an aerosol spray can because airtight packaging is needed to prevent evaporation of the ethyl alcohol active ingredient. This would render the product ineffective.
To use Lysol Spray, we advise saturating a cotton-filled 4x4 gauze sponge. Hold the gauze within one-fourth of an inch of the Lysol Spray orifice and spray until dripping wet. Use the wet gauze sponge to apply a generous, even coat of disinfectant over the surface to be disinfected. After a two-minute contact time, use a second sponge sprayed dripping wet to scrub and clean the surface, which at this time has been disinfected by the initial coating with disinfectant. Dry the surface with a clean paper towel.
We are hopeful that your phenolic-based disinfectant is the cause of the problem and that the substitution of the alcohol-based product will solve your challenge.
PCC has an excellent infection control DVD or VHS tape featuring Dr. Rella Christensen. It discusses and demonstrates all infection-control concepts in the dental office, and it is a powerful in-service education program for your staff. For more information about V2479 or V2479-D "Infection Control Techniques — Step-by-Step!" call (800) 223-6569, fax (801) 226-8637, or visit our Web site at www.pccdental.com.
Question ...
It seems that every article I read on adhesive dentistry has different bond values for the various bonding agents that are supposed to bond composite resin to dentin. How can this conflicting information be correct? Can resin actually be bonded to dentin with predictability, and if so, how long does the bond last?
Answer from Dr. Christensen ...
Your question actually identifies one of my pet peeves. You are entirely correct in stating that different research projects report different adhesion values for various brand names of bonding materials. Bonding composite resin to enamel is reliable, easy, and predictable. It has been well-proven over decades of use. However, bond of resin to dentin is quite another story.
Research on bonding resin restorative materials to dentin uses various laboratory (in vitro) techniques to determine bond values. Some of these techniques report high values, while others report values that are less than half the values of the higher-value techniques. With a few exceptions, it is impossible to compare a bond value from one research project to a value from another project. The exception is when the projects to be compared have been accomplished in the same laboratory, by the same group of researchers, and using the same testing instruments and techniques. It is logical that those people selling specific products prefer to have testing on their products accomplished by laboratories that use testing techniques producing the higher bond values for their product.
What do these bond values really mean? They may have academic meaning to researchers who compare various products every day, but to practitioners, they have minimal value. Some of the reasons for this problem include the following:
• The tests are accomplished in-vitro on extracted human or animal teeth.
• The teeth used in the tests usually come from patients without any patient history relative to age, fluoride content of drinking water, etc.
• Often, clinical conditions are not simulated in the projects.
• Researchers may not have enough clinical experience to know if a technique being tested can be accomplished clinically.
• Seldom are the bonds being tested subjected to the hot-cold variations of the oral cavity, or if they have been tested under such conditions, they may not have been evaluated for a sufficient period of time to validate their accuracy.
• It is difficult to put the bonds under stress that simulates oral conditions.
• There are varying degrees of integrity among researchers and testing facilities, ranging from unquestioned honesty to untrustworthy.
After years of clinical and research experience with enamel and dentin bonding, I can conclude that almost all bonding of composite resin to acid-etched enamel surfaces is acceptable clinically. An exception is the poor retention produced by etching high fluoride-containing enamel surfaces, or irregular, peculiar enamel anatomy.
However, I do not trust dentin bonding. In my clinical experience, I have seen many situations in which restorations literally fell out, even though they were seated over bonding materials showing high laboratory bonding values.
On the occasion of removing resin or bonded ceramic restorations from such bonded dentin surfaces, the most common experience is that the "bonded" material can be removed very easily from underlying dentin after it has served in the mouth for a period of months or years.
Why should a practitioner use dentin bonding agents? There is a measurable amount of retention to dentin offered by most dentin bonding agents as shown in in-vitro laboratory research. The amount of bond is not predictable, and the bond differences among brands are astounding. However, there is an unknown and potentially transient level of bond that should be accepted with caution.
In my opinion, the major reason for using dentin bonding agents is desensitization of underlying dentin surfaces. If a specific bonding agent does not have this property, why use it? Dentistry had decades of restorative success before dentin bonding agents became available.
The current generation of self-etching primers has made a major impact in this area. In most cases, self-etching primers desensitize dentin well, and according to most research projects, they provide the elusive dentin bonds as well as the "total-etch" technique.
In summary of this frustrating topic, enamel bonding is predictable, long-lasting, strong, and has revolutionized dentistry, but dentin bonding has not matured to the same degree. In my opinion, it should be used to desensitize dentin surfaces, accepting any bond that occurs as a fringe benefit.
The following PCC video will help you and your staff to understand and use self-etching primers, and to enjoy the advantage of predictable dentin desensitization — video C901A, "You Need Self-Etching Primers." For more information, call (800) 223-6569, fax (801) 226-8637, or visit our Web site at www.pcc dental.com.
Dr. Christensen is a practicing prosthodontist in Provo, Utah. He is the founder and director of Practical Clinical Courses, an international continuing-education organization for dental professionals initiated in 1981. Dr. Christensen is a co-founder (with his wife, Rella) and senior consultant of Clinical Research Associates, which, since 1976, has conducted research in all areas of dentistry and publishes its findings to the dental profession in the well-known CRA Newsletter. He is an adjunct professor at Brigham Young University and the University of Utah. Dr. Christensen has educational videos and hands-on courses on the above topics available through Practical Clinical Courses. Call (800) 223-6569 or (801) 226-6569.
Dr. Christensen's views do not necessarily reflect the opinions of the editorial staff at Dental Economics.
