Have you noticed the curing-light ads in the dental journals lately? It seems that every issue includes advertisements for several new curing lights, some claimed to have superiority over the others and touting the acceptance of some commercial evaluating group. Don’t we have enough curing lights in the profession? Why is there a frantic rush to produce more lights? Are the current curing lights adequate in their performance, or do we need another generation of lights? The promotion of curing lights reminds me of the entry of the newest models of automobiles near the end of each year. Often, their appearance has been changed from the previous year, but they accomplish the same necessary task—they take you where you need to go.
I remember about 25 years ago when light-cured resin was introduced to the profession. Practitioners wondered why they needed to use a light to polymerize restorative resin, and many dentists resisted the change from autocured resin to light-cured resin. However, the eventual change to and acceptance of light curing took place. Continued changes in wavelength used to cure resin were made, and increases in light intensity were introduced. The result was the removal of potentially harmful ultraviolet light from the curing mechanisms, an increase in light intensity and a decrease in the time required to cure restorative resin. Subsequently, light curing became common in the profession, with standard halogen curing lights dominating the marketplace and autocured resins being used less frequently.
Curing restorative resin with standard halogen lights requires about 30 or more seconds for an adequate cure of an increment of light-colored resin. One company (Kerr, Orange, Calif.) introduced the Turbo Tip. This device increased the intensity of halogen light by focusing it into a large orifice and through fiber-optic bundles of diminishing diameter to a reduced-diameter orifice, much like a nozzle on a water hose. The result was faster curing of resin, allowing cure of a typical light-colored resin in about 10 seconds.
Lasers have been promoted for resin curing, but the high cost and technique sensitivity of these devices have limited their use. Shortly after the introduction of laser curing, high-intensity plasma arc curing, or PAC, lights were introduced. Their curing time was so fast that practitioners were suspicious of them. Time proved the usefulness of the PAC lights, but their high cost and heat production during polymerization somewhat limited their popularity. Nevertheless, users of PAC lights have become strong advocates of this type of light. The next introduction was the light-emitting diode, or LED, curing lights. The original LED lights were relatively low in effectiveness. Only now can some of them be compared with halogen curing lights in terms of efficiency.
This article contains a discussion of the current state-of-the-art in restorative resin curing and makes suggestions relative to the most appropriate use of curing lights in 2004.
 |
A TOUR OF CURING LIGHTS
|
|---|
The array of available curing lights can be confusing. A review of their characteristics may help clarify the strengths and weaknesses of each.
Standard halogen curing lights.
There is nothing wrong with using standard halogen curing lights. They are well-proven, and they cure restorative resin in a reasonable period of time. These are the most commonly used curing lights today, though there is continuing movement toward use of LED lights. Standard halogen curing lights are easy and nonthreatening to use for dentists and staff members alike. They are relatively low-cost on initial purchase, and replacement of burned-out lamps is not expensive. The cost of standard halogen curing lights varies from $300 to $1,400. Typical practices can afford to have several standard halogen lights without major financial sacrifice.
These lights can be made to cure resin faster by using a Turbo Tip. This simple addition of a new curing tip to a standard halogen curing light costs about $231, and the Turbo Tip decreases the time necessary to cure by about 50 percent. As might be expected, the new tip causes an increase in heat that must be taken into consideration. However, this heat generation can be overcome by judicious use of the light, blowing air on the area being cured during use of the light, and controlling the time the light is used in any specific situation. The addition of the Turbo Tip increases the efficiency of the standard halogen curing light to equal that of the fast halogen lights, and the change is effected with minimal cost and little change in the clinical technique.1
Fast halogen curing lights.
The most popular example of this category of lights is the Optilux 501 (Kerr). As evidenced by my many conversations with practitioners, this light has found excellent acceptance among dentists. When used with a Turbo Tip, this is an adequate curing light that leaves little to be desired by current standards. Although the cost of the light is more than that of a standard curing light, its reduction in curing time compensates for its extra cost over a period. The cost of the light is about $1,400. Users of fast halogen curing lights should recognize that their curing method is adequate and acceptable.
You must decide if the light you are using is adequate for your needs, or if you need a new concept or new model. Don’t be too fast to throw away a functional light just to have the newest model.
PAC lights.
About six years ago, PAC lights were introduced to the profession. Practitioners could not believe how quickly the lights cured restorative resin. An average recommended curing time was about three to five seconds for an average increment of a light-colored restorative resin. The advent of the PAC light brought criticism from some researchers who felt that it cured resin too fast, and that subsequent damage to tooth structure and resin would result. The cost of PAC lights was two to four times that of a standard halogen curing light (cost of a plasma arc light ranges from $2,995 to $4,650). Replacement lamps cost from roughly $700 to $1,600, although the life span of these bulbs would make it highly unlikely that one would need to purchase a replacement. However, over a short time, the fast speed of cure compensated for the extra initial cost of the lights. Significant heat generation is inherent with PAC lights, but when used with care, and for the necessary few seconds, the lights have not proved to produce enough heat to cause a clinically observable problem.
There are many PAC lights in everyday use. Allegations that the lights cured too fast and caused damage have not proved to be a significant clinical challenge. Users of PAC lights appear to be hesitant to change to any other form of resin curing. The lights’ speed of cure and the resultant immediate continuity of steps in any resin placement procedure are unequaled by other types of currently popular lights.
In my opinion, judicious users of PAC lights need not look elsewhere for an improvement in light curing.
LED curing lights.
I have gathered from the dentists who attend my speaking engagements that LED lights are being purchased by many practitioners. What is the appeal of this type of curing light? Dentists tell me that its relatively moderate cost, its recently increased intensity, its portability and the long use life of its diodes all are attractive. The LED lights cure in a range of time from that of a standard halogen light to that of a fast halogen curing light. Additionally, some of the LED lights are cordless and smaller in size, allowing easier use. The LED lights do not generate as much heat as do other lights. Potentially, the LED lights have a long use life without replacement of parts. These positive characteristics, cleverly advertised by manufacturers, have influenced dentists to change to LED lights.
Is this type of light better than other types discussed in this article? Standard halogen lights, fast halogen lights or PAC lights can cure resin as well as or better than the current generation of LED lights. If the positive characteristics of LED lights are attractive to you, and your other lights are worn out, purchase an LED light. However, do not move to an LED light thinking you will have a more effective curing instrument. There are several very good LED curing lights that will cure resins made by the lights’ respective manufacturers. However, at this time, the only LED light that will cure all resins tested in the study is the Ultralume 5 (Ultradent Products, South Jordan, Utah).2 It is possible that in the near future, continued improvements in LED lights will make all of them so much better than the other described curing-light types that a move to LED will be highly justified.
High-intensity halogen curing lights.
Recently, a Swiss company introduced the first closed-system water-cooled halogen light, the Swiss Master Light (EMS-Electro Medical Systems S.A., Nyon, Switzerland). The unit produces a light that is several times more intense than the emissions of the typical halogen curing lights. The heat of the light is dissipated by water-cooling instead of fan-cooling. It has a built-in radiometer, disposable curing tips and a fast curing time. The cost is higher than that of other halogen lights ($2,900 retail). Continued research in both basic science and clinical areas must be accomplished on this type of light to confirm the acceptability of the concept.3
|
WHAT CHARACTERISTICS DO YOU WANT IN A CURING LIGHT?
|
|---|
Most dentists want an easy-to-use, efficient, easy-to-maintain, durable, fast, well-proven, moderate-cost, ergonomically acceptable curing light. Most of the light types described can fit these characteristics. You must decide if the light you are using is adequate for your needs, or if you need a new concept or new model. Don’t be too fast to throw away a functional light just to have the newest model.
|
SUMMARY
|
|---|
In the approximately 25 years that dental restorative resins have been cured by light, there has been constant evolution of and improvement in the curing devices and the resins they cure. During the past decade, curing lights have become very effective. Dentists who have functional halogen, fast halogen or PAC lights may wish to compare their current lights with the new generation of LED lights that are dominating the commercial dental advertising at this time. If the new LED lights offer more than the current light they are using, they might consider changing to an LED. If their current light offers about the same characteristics as the LED light being considered, I do not recommend changing. I anticipate that continued upgrading and improvement in LED lights eventually will make this concept the most used method for curing restorative resin.
TOP
A TOUR OF CURING...
WHAT CHARACTERISTICS DO YOU...
