UCSF

ABSTRACT

INTRODUCTION: Lasers are now used for several applications in dentistry. They offer many advantages to the dental field over traditional high-speed handpieces. Lasers that are computer controlled in conjunction with optical methods of feedback can conservatively ablate composite from healthy enamel and dentin. Due to composite’s similarity in appearance with natural dentition, composite restorations are difficult to remove without damage to healthy tooth structure in practice. This damage to healthy tooth structure can be minimized with spectral guidance and computer controlled lasers. The hypothesis tested in this study is that composite can be safely and selectively removed from tooth surfaces at clinically relevant rates using laser ablation in conjunction with spectral feedback as compared to removal using a high-speed handpiece.

METHODS: A CO₂ laser, a computer-controlled galvanometer based scanning system, and a spectral discrimination system were used for the removal of composite from enamel and dentin surfaces. Subjects (N=8) being treated at the UCSF Orthodontics post-doc clinic were recruited for this study. Subjects were 18+ years old and scheduled for bilateral premolar extractions. Premolars to be extracted were screened to have a significant section of the occlusal portions with healthy, untouched enamel. Patients were seen in two visits: The first visit consisted of occlusal preparations of the two premolars, scanning of the preparations with OCT, and restoring with composite. The second visit consisted of removing the composite with laser technology or the traditional high-speed hand piece and scanning the results. Patients subsequently completed extractions. Data from the scans were analyzed to compare the initial cavity preparation volume with resulting cavity volume after composite removal by laser or high-speed handpiece.

RESULTS: Volumetric data obtained from OCT scans were analyzed via a data visualization software. There was no significant difference (P<0.05) in initial preparation size across all patients. Volumetric differences of composite removal revealed no significant differences between handpiece vs CO₂ laser methods.

CONCLUSIONS: There was no significant difference in terms damage to enamel or totality of composite removed, but this study indicates favorably that the CO₂ laser set up with automated feedback for the selective ablation of dental composite can be used clinically.