# Dry Ice in Decoverslipping Microscopic Slides: A Novel Approach

## TL;DR

This study shows that dry ice is a faster and safer alternative to xylene for removing coverslips from old histopathological slides without damaging the tissue or staining quality.

## Contribution

The study introduces dry ice as a novel, efficient, and safer method for decoverslipping compared to traditional xylene use.

## Key findings

- Dry ice removed coverslips in about 65 seconds, while xylene took around 4 days.
- Dry ice caused minor tissue distortion, but it was not statistically significant.
- Both methods produced comparable staining results after restaining with H&E.

## Abstract

Introduction: Histopathological slides play a pivotal role in diagnostic pathology; however, over time, preserved slides may exhibit fading of staining quality, thereby diminishing their diagnostic and research value. Histopathological laboratories perform coverslip removal techniques to enable restaining of histopathological slides. Conventionally, xylene is used for coverslip removal; however, it is a time-consuming process. To tackle this, dry ice, a widely accessible and cost-effective cooling agent with a low freezing point (-78.5°C), was used for coverslip removal and compared with conventional xylene.

Aim: This study aimed to evaluate the effectiveness of dry ice vs xylene in decoverslipping microscopic slides.

Materials and methods: A retrospective study was conducted by the Department of Oral and Maxillofacial Pathology and Microbiology, in which 56 archival slides collected over a 15-year period were randomly selected for coverslip removal. These faded slides were categorized into four groups, each denoting a four-year interval, and evenly divided between dry ice and xylene. Coverslip removal time was recorded with a stopwatch, and slides were examined under a stereomicroscope for tissue damage and then immersed in xylene to eliminate residual dibutylphthalate polystyrene xylene (DPX). Finally, tissue sections were restained with hematoxylin and eosin (H&E) stain.

Result: The mean time required for coverslip removal with dry ice was 65 ± 17.760 seconds, whereas xylene required 4 ± 1.440 days. Dry ice caused minor tissue distortion, though not statistically significant (p = 0.075). After H&E restaining, both procedures produced comparable staining results (p = 1.00).

Conclusion: Dry ice removes coverslips quicker and more effectively than xylene, with minimal tissue distortion and preserved staining quality. It also avoids xylene's adverse health and environmental effects, making it an improved laboratory choice.