Effectiveness of household ultrasonic cleaning with chemical agents on thermoplastic retainers: A clinical study

The combination of mechanical and chemical cleaning methods is an effective way to remove biofilms from retainers. This study aimed to evaluate the effectiveness of household ultrasonic cleaning with chlorhexidine (CHX) in reducing microbial contamination on Essix ACE orthodontic retainers; in addition, its effects on color stability, surface roughness, and microhardness were examined.

This prospective crossover study comprised 11 orthodontic patients (3 males and 8 females), each of whom sequentially wore 4 maxillary Essix ACE retainers, with each retainer subjected to a different cleaning method: brushing with fluoride toothpaste, brushing with 1% CHX gluconate, ultrasonic cleaning with 0.12% CHX mouthwash, and ultrasonic cleaning with water. Each method was used at night for 14 days, with a new retainer introduced at each phase. Microbial contamination was assessed using ATP bioluminescence and expressed in relative light units. The properties of the retainers were evaluated by measuring the color change, surface roughness, and microhardness. Data were analyzed using the Friedman test followed by Dunn's post-hoc analysis with Bonferroni adjustment.

Ultrasonic cleaning with CHX mouthwash exhibited the lowest microbial contamination, followed by brushing with CHX, brushing with toothpaste, and ultrasonic cleaning with water. Significant differences were observed among the methods (P <0.001): ultrasonic cleaning using water differed from all others, whereas brushing with toothpaste differed from ultrasonic cleaning with CHX. No significant differences were observed in color change, surface roughness, or microhardness across all methods (P >0.05).

This study is the first to demonstrate that using household ultrasonic cleaning with CHX mouthwash is effective for maintaining Essix retainer hygiene without compromising the properties of the material.