Background: Different parameters of Erbium:Yttrium-Aluminum Garnet (Er:YAG) laser were considered in treatment of dentin hypersensitivity in previous clinical and in vitro sudies.
Aim: To investigate the morphological aspects of inversely altering energy level and exposure time of Er:YAG laser on exposed dentinal tubules in-vitro.
Methodology: Ten human freshly extracted sound third molars were collected. Their crowns were horizontally then vertically sectioned to expose transverse and longitudinal sections of DTs respectively. The obtained 20 specimens were divided into four groups (n=5) after exposure to 35% phosphoric acid. Group LI (irradiated with Er:YAG laser of 80 mJ energy and 60 seconds exposure time), group LII (irradiated with Er:YAG laser of 120 mJ energy and 30 seconds exposure time). Control groups (CI and CII) were not irradiated. Specimens were assessed by scanning electron microscope (SEM) provided with digitizer and the depth of laser impact was measured in irradiated groups for statistical analysis.
Results: Increasing energy and decreasing exposure time of Er:YAG laser in group LII adequately occluded exposed DTs, but depth of laser impact was significantly reduced compared to group LI. Moreover in group LII, the morphology of pulpal end of the DTs was adversely affected
Conclusion: Er:YAG laser parameters set of (80 mJ, 5 Hz, 60 s), under water spray was effective in occluding exposed dentinal tubules and harmless to deep dentin tissues which could provide a safe dentin hypersensitivity treatment that further needs to be assessed clinically.