Histological Evaluation of Traumatic Changes in the Dental Pulp After Removal of Dental Restorations

Objectives: Multiple exogenous stimuli, which can cause changes at the histological level, affect the dental pulp. Such a stimulus could be present during the removal of dental restorations, especially by the use of laser light. In the present study, methods were established to qualitatively and quantitatively assess histological changes in the dental pulp after removal of ceramic restorations and brackets.
Methods: In the ReversFix study (EUDAMED No.: CIV-16-04-015244), 60 vital, non-maintainable teeth were restored with ceramic brackets, veneers or complete crowns. Restoration removal was performed either conventionally (control group) or by using an Er:YAG laser-assisted procedure (intervention group). One week after the removal, the study tooth was extracted and histologically prepared. The resulting parafin sections were used as a basis for the development of a new score for the qualitative evaluation of possible traumatic changes that may have developed and for the quantitative observation of the blood vessels.
Results: To establish a score, the first step is to stain the parafin sections with a hematoxylin-eosin stain and evaluate their suitability by pre-assessing the pulpal status. This is followed by a qualitative evaluation of the pulp by looking at six different characteristics: odontoblast layer, vacuoles in the odontoblast layer, structure of the pulp, denticle formation, tertiary dentin formation, and type of inflammation. In addition, the parafin sections are digitized with a slide scanner. The area (µm²) of the dentin of the sectioned tooth as well as the area of the pulp can be determined on the digitized tooth sections. In addition, the same method can be used to determine the total surface area of the blood vessel segments and their proportion within the pulp in order to evaluate them as a correlate for the inflammatory state.
Conclusions: The histological preparation of human teeth allows a more detailed diagnosis of the condition of the pulp than is achievable with clinical methods. To differentiate the causing stimulus of the pathological change in the pulp, the clinical history of the tooth must also be considered.