Objectives: The aim of this study was to evaluate histologically the immediate effect of two types of air-polishing devices (APDs) on the gingiva.
Material and methods: The buccal gingiva in four mongrel dogs was exposed to 5, 10 and 20 s of instrumentation, applying a hand-piece type of APD (HP-APD) PROPHYflex and a stand-alone type of APD (SA-APD) Jetpolisher in a split-mouth design. Immediately after treatment, the exposed gingiva was excised by sharp dissection and fixed in 10% buffered formalin. For each specimen, 15 sections, 20 microm apart, corresponding to the central part of the treated and control untreated gingiva were cut and stained with haematoxylin and eosin. Stained sections were examined histomorphometrically for keratin width and epithelial cell layer (ECL) (prickle and basal cell layers) width. Extent of erosion was expressed as loss of keratin and ECL compared with control.
Results: Microscopic examination presented changes in keratin and ECL, including keratin detachment and disruption of the normal ECL architecture. The erosive changes in the gingiva caused by both APD, positively correlated with instrumentation time (p<0.001) and type of instrument (p=0.008). Keratin loss was significantly higher for SA APD than for the HP APD in each time interval (p=0.019). Following exposure for 5 s, both APD caused a 25% loss of the ECL. Exposure for 10 and 20 s revealed a significantly greater ECL loss caused by the SA-APD than the HP-APD (p=0.018). Exposure for 20 s was the only time interval that presented the area of total epithelium erosion with SA-APD causing significantly more (p=0.002) areas of total epithelial erosion than the HP-APD.
Conclusion: Gingiva exposure to air-polishing slurry delivered by APD caused localized trauma because of epithelial erosive changes with severity, positively correlated with instrumentation time and design principles of the applied APD. The clinician should be aware of the potential insult of the gingiva when applying the APD and careful precautions should be taken.