Physical, acoustical, and psycholphysical comparisons between earmolds resulting from poly (ethyl methacrylate) and condensation reaction silicone ear impression material

ne of the most pressing problems facing the hearing health care profession is the issue of remakes due to acoustic feedback and poor physical fit. Information regarding ear impression materials suggests that the problem lies within poor impression techniques, poor impression materials, or a combination of the two.

Ear impressions were obtained for twelve subjects with poly(ethyl methacrylate) and condensation reaction silicone ear impression materials at their amplified ear. These impressions were processed into lucite earinolds which were compared in terms of physical dimensions, real ear acoustic gain, and subjective preference.

The results do not seem to support a clear advantage for either impression material. Clinical experience with earmolds made from poly{ethyl methacrylate) impression material, however, continue to result in problems with acoustic feedback and poor physical fit. The results from this study, which did not exhibit difficulties with acoustic feedback or poor physical fit, indicated that poly(ethyl methacrylate) can be successful ly used clinical ly only in conjunction with the controls, such as careful mixture ratios, completeness of mixing, and expediency of processing, which were utilized in the present study.