Caries Inhibition With a CO2 9.3mm Laser: An In Vitro Study

Caries Inhibition With a CO₂ 9.3mmLaser: An In Vitro Study

Peter Rechmann, DMD, PhD, Beate M.T. Rechmann, William H. Groves Jr., Charles Q. Le, Marcia L. Rapozo-Hilo, Richard Kinsel, DDS, and John D.B. Featherstone, MSc, PhD

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ABSTRACT

Objective:

The caries preventive effects of different laser wavelengths have been studied in the laboratory as well as in pilot clinical trials. The objective of this in vitro study was to evaluate whether irradiation with a new 9.3 mm microsecond short-pulsed CO₂-laser could enhance enamel caries resistance with and without additional fluoride applications.

Methods

One hundred and one human tooth enamel samples were divided into seven groups. Each group was treated with different laser parameters (CO₂-laser, wavelength 9.3 mm, 43 Hz pulserepetition rate, pulse duration between 3ms at 1.5 mJ/ pulse to 7ms at 2.9 mJ/pulse). A laboratory pH-cycling model followed by cross-sectional microhardness testing determined the mean relative mineral loss delta Z (DZ) for each group to assess caries inhibition in tooth enamel by the CO₂ 9.3mm short-pulsed laser irradiation. The pHcycling was performed with or without additional fluoride.

Results

The non-laser control groups with additional fluoride had a relative mineral loss (DZ, vol%μmmm) that ranged between 646±215 and 773±223 (mean±SD). The laser irradiated and fluoride treated samples had a mean DZ ranging between 209±133 and 403±245 for an average 55%±9% reduction in mineral loss (ANOVA test, P<0.0001). Increased mean mineral loss (DZ between 1166±571 and 1339±347) was found for the non-laser treated controls without additional fluoride. In contrast, the laser treated groups without additional fluoride showed a DZ between 470±240 and 669±209 (ANOVA test, P<0.0001) representing an average 53%±11% reduction in mineral loss. Scanning electron microscopical assessment revealed that 3ms pulses did not markedly change the enamel surface, while 7ms pulses caused some enamel ablation.

Conclusions

The CO₂ 9.3mm short-pulsed laser energy renders enamel caries resistant with and without additional fluoride use. The observed enhanced acid resistance occurred with the laser irradiation parameters used without obvious melting of the enamel surface aswell as after irradiationwith energies causing cutting of the enamel. Lasers Surg. Med. 48:546–554, 2016. Published 2016. This article is a U.S. Government work and is in the public domain in the USA