Prior to deciding which curing light to buy, the following china dental unit supplier’s data (as well as evidence to that effect) must be analyzed:

1. What is the irradiance at the curing light tip, and what is the change in irradiance as the tip is moved to a clinically relevant distance of 8 mm from the composite surface?

Many curing lights exhibit a rapid drop in irradiance (75 percent or more) over that distance. The practitioner may purchase a seemingly “powerful” curing light that actually cures very little at the composite surface. Consider the high power Light D (center tip irradiance 7,000 mW/cm2) that delivers the same irradiance as the low power Light E at the clinically relevant distance of 8 mm.

There is a significant challenge in light-curing Class II composite resins at the gingival margin of the proximal box. The clinical implications of inadequate light curing include significantly higher rates of gingival marginal caries when compared to amalgam restorations.

Inadequate light curing may, in fact, be a significant culprit for premature Class II composite failure at the gingival margin of the proximal box. The gingival marginal area is the high-risk area for recurrent caries where defects first initiate. Xu and coworkers investigated composite resin adhesion as the distance from the light guide increased, a study prompted by the number of publications demonstrating poor marginal seal and increased microleakage at the gingival margins when compared to the occlusal enamel margins.

2. What is the curing light’s beam profile? Is the irradiance evenly distributed across the guide tip surface?

Beam profile refers to the distribution of polymerizing blue light across the surface of the light guide tip. Many curing lights have an unevenly distributed blue light emission across the light tip; intense hot spots provide effective polymerization while intense cold spots do not. he table indicates how the beam profile color translates to irradiance. It is important to note that violet in the beam profile signifies inadequate irradiance to cure a composite resin within 20 seconds, as in the gingival margin and proximal box areas with some of the curing lights portrayed.

3. What are the heating effects associated with the curing light?

Some curing lights can increase surface temperature up to 80° Celsius in just a few seconds. Other dental curing lights may increase pulpal temperatures dangerously, more than 5.5° Celsius, even when within recommended curing times. The risk of dangerous pulpal temperature increase is exacerbated when curing times are arbitrarily increased without concomitant heat management techniques such as increasing the waiting time and/or air cooling the tooth between polymerization cycles.

When utilizing extended curing times, a wait-time of 1-2 seconds between every 10 seconds cycle or air-cooling is recommended. In polymerizing Class V restorations, the curing light’s heat can cause gingival tissue damage. The practitioner must assure that increased curing times do not damage hard, soft, or pulpal.

Original source: http://www.oyodental.com/Some-Questions-About-Dental-Curing-Light

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