Corrosion of Dental Solders by Effervescent Cleansers

Objectives: Failure of soldered joints in prosthodontic and orthodontic devices is a common and frequent problem when they are exposed to certain effervescent cleansers. This study evaluates the corrosive potential of a selection of commercial effervescent cleansers. Methods: Strips of silver solders (Unitek and Sun-Platinum) were immersed for 10 days in different commercial effervescent cleansers (Products A, B, C and D). The cleansing solutions were changed 2X daily and the weight changes were monitored. In a second study, Degussa silver solder was coupled to two different Co-Cr alloys (Dentaurum and Vitallium) in freshly prepared effervescent cleansers (Products A, C, D and E) via a zero resistance ammeter (ZRA) and the galvanic corrosion current was monitored over 10 minutes. All effervescent solutions were prepared in accordance with manufacturers' instructions: 1 tablet/150 ml warm (120°F) water. All studies were performed at least in duplicate. Results: Corrosion rates of solders varied with the type of solder and the effervescent cleanser in both the immersion and ZRA electrochemical studies. The data indicate that cleansers C and D are more aggressive towards solders than Products A and B under long-term immersion conditions. The same trends are followed when solders are coupled to Co-Cr alloys but only Products C and E caused minimal corrosion in the galvanic couple. Conclusions: This pilot study confirmed that certain effervescent cleansers appear to be very aggressive towards silver solders. The corrosive effects are exacerbated when the solders are coupled to a more noble metal.