UCSF

In vivo occlusal caries prevention by pulsed CO₂ laser treatment quantified by QLF

Tiffany H. Hsu

Purpose: High caries prevalence in occlusal pits and fissures of permanent molars warrants novel caries prevention methods. Rechmann et. al. (SPIE 2008) reported 86% reduction in smooth surface caries following treatment by specific CO₂ laser irradiation. This study's purpose was to conduct a blinded 12–month pilot scale clinical trial of occlusal pit and fissure caries inhibition in humans using the same CO₂ laser irradiation conditions.

Methods: Twenty subjects, average age 13 years, were recruited. At baseline, second molars were randomized into test and control groups, assessed by International Caries Detection & Assessment System (ICDAS) and Quantitative Light–Induced Fluorescence (QLF). An independent investigator irradiated test molars with Pulse Systems (New Mexico) 9.6μm clinical CO₂ laser, average fluence (energy/surface area) 3.4±0.3J/cm² per pulse, pulse duration of 20μs. At 6–month and 12–month recall, teeth were assessed by ICDAS and QLF.

Results: Of 20 subjects, 17 completed the 6–month recall and 14 completed the 12–month recall. ICDAS: At 6–months, average ICDAS score changes were 0.50 (SE 0.15) and 0.53 (SE 0.17) for test and control molars respectively. At 12–months, average ICDAS score changes were 0.40 (SE 0.19) and 0.57 (SE 0.23) for test and control molars respectively. The 6– and 12–month results showed no statistically significant differences (P>.05, Student unpaired t–test) in ICDAS score change between test and control molars. QLF: Qualitatively, the QLF images correlated closely to what was observed from ICDAS visual examination. Quantitatively, at 6–months, average ΔF changes were −0.78% (SE 0.38) and 0.36% (SE 0.75) for test and control molars respectively. The 6–month results showed no statistically significant differences (P>.05, Student unpaired t–test) in ΔF changes between test and control molars. At 12–months, average ΔF changes were −1.13% (SE 0.34) and 0.31% (SE 0.38) for test and control molars respectively. The 12–month results showed a statistically significant difference in ΔF changes of test molars compared with control molars (P=.01, Student unpaired t–test).

Conclusions: Although this laser treatment markedly inhibited caries progression in the smooth surface laser study, the same result was not found for pits and fissures, likely due to design limitations of the laser delivery system.