Purpose of the study: To comparatively evaluate the effect of height differences on the retention and wear behaviour of ball attachment system over mandibular dual implants. Materials and methods: Two groups of twenty samples each containing polymerised master block of dual implant analogues at same height in Group 1 and dual implant analogues of different heights in Group 2 were fabricated along with ball abutments, nylon cap and metal housing. Qualitative analysis of samples for wear factor

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... re carried out using stereomicroscope and quantitative analysis of retention force at baseline, 360, 720, 1080, 1440 insertion-removal cycles were determined using Universal testing machine. statistical analysis were carried out using independent 't' test and paired sample 't' test.