Impact of air-polishing using erythritol on surface roughness and substance loss in dental hard tissue: An ex vivo study

Abstract

This ex vivo study aimed to investigate surface roughness and substance loss after treatment with different professional cleaning methods and to determine whether subsequent polishing with a rubber cup and polishing paste is necessary. Samples (flat and natural surfaces) of human enamel and dentin were prepared (baseline) and treated with either a curette, air-polishing with erythritol, a rubber cup and polishing paste, or a combination thereof (treatment). Subsequently, all samples were immersed in an ultrasonic bath (ultrasonic) to remove residues from the treatment procedures. The surface roughness values sRa and sRz as well as tissue loss were measured profilometrically. Linear regression models were used to compare group differences (roughness and loss) considering the corresponding baseline value. The significance level was set at p<0.05. sRa increased significantly after treatment with curettes or air-polishing with erythritol in both enamel (p<0.001) and dentin (p<0.001) of flat samples. The same effect was observed for sRz in dentin (p<0.001) but not for enamel compared to negative control. Polishing with a rubber cup and paste alone had no significant effect on roughness values. When combined with other treatments, the effect of curette or air-polishing with erythritol dominated the effect. In enamel, none of the tested methods led to measurable tissue loss. In dentin, air-polishing with erythritol caused ≤50% tissue loss compared to the curette. Conclusively, for enamel, treatment effects on roughness were measurable but of limited clinical relevance. For dentin, air-polishing resulted in a smaller but insignificant roughness increase and less tissue loss compared to the curette. Polishing with a rubber cup and paste did not affect surface roughness. Regarding the clinical application, the use of air-polishing seems to be a less invasive procedure than using a curette; polishing with rubber cup and paste offers no advantage in terms of reducing roughness as a final procedure.

Fig 1. Flow chart of study procedures.

Fig 2. Example for a flat enamel sample.

(a) Sample fixed on a glas slide with light curing acrylic resin. (b) Glas slide with flat enamel sample mounted to the bench. The surface was half covered with a tape to create a reference area that allows loss measurement. The tape was removed prior to loss measurement. The fixation of the sample on the bench allows using a standardized angle with the curette or the air-polisher.

Fig 3. sRa and sRz for single treatments.

Boxplots for dentin surfaces (flat/natural) with differences for sRa/sRz of treatment/baseline for treatment Groups 1, 2, 3, and 8 (negative control). In groups 3 and 8, only a smaller number of measurements could be performed because the adhesive bond between the sample and the slide had failed.

Fig 4. sRa and sRz for combinations of treatments.

Boxplots for dentin surfaces (flat/natural) with differences for sRa/sRz of treatment-baseline for treatment Groups 4, 5, 6, and 7.

Fig 5. 3D visualization of the surface roughness profile.

Depiction of the measuring area (1 mm x 1 mm) of flat samples of enamel (a-e) and dentin (f-j) in μm. a/f = curette, b/g = air-polishing c/h = rubber cup, d/i = combination of three, e/j = negative.

Fig 6. Surface loss values (μm) obtained from flat dentin samples.

The different letters above indicate differences between groups.