In vitro safety evaluation of a new ultrasound power toothbrush

To evaluate the safety of a novel ultrasound power toothbrush using a series of laboratory tests simulating extended brushing on the natural tooth surface, dental restorations, crowns, and orthodontic brackets.

To evaluate safety on the natural tooth and restored surfaces, human molars (n = 60) were prepared with restorations centered on the facial cementoenamel junction. The specimens received restorations of either 1) amalgam, 2) nanofilled composite resin, 3) glass ionomer, 4) cast gold-cemented with glass ionomer, or 5) pressed ceramic adhesively cemented with a composite resin cement. Orthodontic specimens (n = 33) were created by cementing brackets onto the buccal surfaces of extracted teeth. Crown specimens (n = 32) were created by cementing cast metal crowns onto identical pre-molar metal dies using zinc phosphate. All specimens were exposed to extended brushing in an environment controlled for time, brush head force, and dentifrice slurry. Treatment was assigned randomly to the specimens, and brushing was done with either the ultrasound toothbrush (Ultreo), or one of two positive controls: a manual toothbrush (Oral-B 35) and an oscillating-rotating power toothbrush (Oral-B Triumph). Negative control specimens remained unbrushed. Qualitative analysis via scanning electron microscopy was utilized to evaluate the tooth surface and restoration integrity. Shear and tensile testing was used to evaluate orthodontic bracket and crown retention, respectively.

Exposure of the teeth and restored surface to the manual toothbrush resulted in some bristle furrows on cementum/dentin root surfaces, especially at the heights of contour and light grooves on the composite resin surfaces. The two power toothbrushes had no signs of root surface wear. None of the toothbrushes demonstrated breakdown of the restorative margins, any loss of cement, or any effect on the enamel. No significant treatment effect on the orthodontic bracket or crown retention force was found (ANOVA, p > 0.05).

The new Ultrasound toothbrush was found to be safe on natural tooth surfaces and restorative materials, as established in comparison to positive and negative controls. Furthermore, no safety concerns related to orthodontic bracket or dental crown retention were identified with any treatment.