Decomposition of Ag-based soldering alloys used in space maintainers after intra-oral exposure. A retrieval analysis study

Abstract

Both soldering alloys demonstrated a significant Cu and Zn reduction after intra-oral exposure that may raise biocompatibility concerns.

Metallurgical and electrochemical characterization of contemporary silver-based soldering alloys

“…9 Therefore, similar behavior is anticipated for the remaining alloys based on similarities in elemental composition and structure. Interestingly, the decrease in the Cu content for DEN after intraoral aging of space maintainers was threefold less compared to that of LEO.…”

“…4 However, many experimental studies have documented that this system is very prone to decomposition of Cu and Zn, 5-8 a finding which has been recently verified by clinical data. 9,10 The clinical implication of this phenomenon is twofold: First, the joint itself undergoes mechanical degradation, 11,12 which has been associated with early failure of space maintainers. [13][14][15][16] Second, and more importantly, there are possible adverse biological consequences-throughout the literature, Ag-based solders demonstrated the worst biocompatibility, showing the greatest reduction in cell proliferation in comparison with other orthodontic metallic materials.…”

Metallurgical characterization of experimental Ag-based soldering alloys

“…The absence of Cu and Zn of the experimental alloys may lead to new alloy formulations which will be less prone to intraoral degradation compared to the commercial ones (Freitas et al, 2011;Soteriou et al, 2014). It is worth noting that the properties of experimental alloys might be further enhanced by a specific thermal treatment (annealing) (Gunnaes et al, 2000).…”

“…Contemporary Ag-based soldering alloys have a variety of formulations based on the Ag-ZnCu ternary system with additions of Ni or Sn and complex microstructures consisting mainly a mixture of a Ag-rich and Cu-rich face centered cubic phases (Ntasi et al, 2013). However recent studies have documented the in vivo release of Cu and Zn (Freitas et al, 2011;Soteriou et al, 2014) verifying the data of experimental studies (Heidemann et al, 2002;Mikulewicz et al, 2012Mikulewicz et al, , 2014Ntasi et al, 2013;Staffolani et al, 1999). The implication of this finding is in first place the mechanical degradation of joint itself which in case of space maintainers has been associated with early failures (Baroni et al, 1994;Bock et al, 2008;Qudeimat and Fayle, 1998;Rajab, 2002;Tulonuglu et al, 2005;Vahed et al, 2007).…”

Adverse reactions to orthodontic materials

“…The clinician should be familiar with the composition of silver‐based alloy solder and, more particularly, with the quantities of copper and zinc. Intraorally, aged silver soldering alloys used in space maintainers have demonstrated a substantial increase in surface roughness and significant copper and zinc reduction which may raise biocompatibility concerns. Soldered orthodontic appliances should be well polished prior to placement so that ionic release is minimised but, preferably, gold‐based brazing materials should be used.…”