Direct Pulp Capping in Dog’s Teeth after Er:YAG Preparation-Histological Study

Methods: The experiment was carried out in a dog at the age 1.5 years old and 25 kg of weight with permanent dentition. Four cavity preparations and a communication with the dental pulp (D<1mm) of maxilla and mandible premolars and molars were made by Er:YAG dental laser (Lite Touch) with sapphire tips (D-0.8mm, L-17mm) using the software of the device. Two of the cavities were filled entirely with tricalcium-silicate based material (Biodentine) and in two of the preparations calcium hydroxide cement (Dycal) was put as a liner and glass ionomer obturations were made. The materials were mixed and applied according to the instructions of the producers. Ninety days after the beginning of the experiment the investigated teeth were fixed in 10% formalin solution, dematerialized, cut in 5 μm slices and stained. The histological samples were observed by microscope (Olympus BX 51) with a built in photo camera. The odontoblast and pre-dentin zones, blood vessels near by the cavity preparation and dentin bridge forming were examined. 

Results: There are histological evidences of normal pulp tissue and a thick dentin bridge with regular dentin tubules and no tunnel defects under the preparation in the ninetieth day samples with tricalcium-silicate based material. The specimens with calcium hydroxide cement show signs of over stimulated peripheral cell zone, pulp metaplasia and free and wall attached calcium inclusions.                                                                                     

Conclusion: Direct pulp capping with tricalcium-silicate based material after Er:YAG dental laser hard tissue preparation provides optimal conditions for a pulp regeneration process and a dentin bridge forming.