Is there a "sweet spot" for the right amount of magnification when examining a patient? How does the naked eye versus the use of loupes affect a dentist's judgment?
A study presented during a poster session at the 2011 International Association for Dental Research (IADR) conference in San Diego sought to learn more about the relationship between magnification and treatment decision-making when evaluating caries lesions.
Previously, there was little concrete understanding about the connection. But a three-year study conducted by researchers from Indiana University and the University of Michigan found that magnification up to 5.5x can affect a practitioner's treatment decisions for occlusal carious lesions. Some variation between examiners existed as well.
— Aaron Stump, DDS
The study's participants -- two faculty dentists and one dental student -- decided upon "significantly less invasive treatment" without the use of loupes compared with using 3.5x and 5.5x magnification.
"The treatment decision variations were the meat and potatoes of our study, looking at a carious lesion with the naked eye and how treatment decisions differ when magnification is used," Aaron Stump, DDS, from the Indiana University School of Dentistry, told DrBicuspid.com.
The decision-making process is what most interested Dr. Stump's team.
"Visualizing the carious lesions is one thing. Treating them, ultimately, is what the dentist has to decide upon," he said. "Because they're going through the severity of the lesion in their mind and making a decision: Are they going to do nothing and watch it, go with preventive treatment such as sealants or fluoride, or actually restore the tooth with amalgam, composite, etc.?"
To make the comparison, 96 permanent human molars were chosen based on the International Caries Detection and Assessment System (ICDAS) II criteria with a severity score of 0 to 4. After being placed in eight dentoform mannequins to simulate clinical conditions, the molars were assessed for treatment choices: none, preventive treatment with fluoride, sealants or restorative.
Intraexaminer repeatability was deemed acceptable. "We were looking for weight kappas above 0.6, and we essentially hit all those," Dr. Stump explained. "There's a 0.58 in there. So we all agreed with ourselves from one day to the next."
Intraexaminer agreement was high without the use of loupes with weighted kappas greater than 0.65 but it started to decrease as the magnification power increased.
Examiner 1 opted for less treatment at 0x than at 2.5x magnification, while the other two examiners' responses were not significantly different. Going from 2.5x to 3.5x, examiner 3 chose less treatment at the lower magnification, while examiners 1 and 2 chose the same level of treatment.
Magnifications of 2.5x and 3.5x resulted in the same recommendations at 5.5x for examiner 2, while examiners 1 and 3 suggested more treatment at the highest magnification.
"The restorative dentist really doesn't use high magnification, such as 5.5x, for routine restorations," Dr. Stump said. "When you're doing your restoration, you can kind of get blinded by looking at such a small field." Consequently, treating carious lesions with such high magnification may be impractical.
The trend in the participants' responses shed light on which magnification levels impacted treatment decisions.
"Our hypothesis was that the different magnification wouldn't have an effect on the treatment decision of the carious lesion," he noted. "We found that the treatment decisions started to significantly change as the magnification increased."
