A new thermographic and fluorescent method for tuning photoablative laser removal of the gingival epithelium in patients with chronic periodontitis and hyperpigmentation.

OBJECTIVE

The purpose of this study was to optimize gingival laser photoablation by thermographic and autofluorescent feedbacks.

BACKGROUND DATA: Photoablative laser treatment is commonly used for gingival de-epithelization in patients with chronic periodontitis or hyperpigmentation. The reduction of collateral thermal damage of periodontal tissues is crucial for optimal treatment outcome.

METHODS

Nineteen patients with chronic periodontitis, seven of whom showing gingival hyperpigmentation, were subjected to de-epithelization with an 810 nm diode laser used in continuous (1 W, 66.67 J/cm2) or pulsed wave mode (69 μJ, 18 μs, 8000 Hz, corresponding to peak/mean power of 3.8 W/0.6 W, 40 J/cm2), depending upon individual gingival features. Photoablation was controlled in real time with a 405 nm violet light probe, which stimulated a yellow autofluorescence of the laser-coagulated tissue. The temperature at the target tissue was controlled with an infrared thermographic probe. When appropriate, small biopsies were taken to evaluate epithelial ablation and thermal effects.

RESULTS

The energy density transferred to the treated tissue surface was computed based on the irradiation modality of the target tissues. Laser photoablation performed under thermographic control yielded complete removal of the gingival epithelium with minimal injury to the underlying lamina propria. Irradiation-evoked autofluorescence, conceivably the result of epithelial keratins, allowed very sharp recognition of the borders between laser-ablated and intact epithelium, thus preventing repeated irradiation.

CONCLUSIONS

This study further supports the favorable characteristics of photoablative diode laser for gingival de-epithelization. Concurrent thermographic and fluorescent analysis can provide substantial help to the setup of a safe and well-tolerated protocol.