Technique Tips Prosthodontics: The Admix Impression

The ‘admix impression’ is a definitive secondary impression technique used in the management of severely resorbed mandibular ridges covered with atrophic mucosa.¹ First described by McCord and Tyson, it involves the use of a viscous admix of impression cake compound and greenstick tracing compound.² Mandibular ridges equating to Cawood and Howell ridge classification V and VI often pose clinical challenges when constructing a satisfactory conventional complete denture.³ As the mandibular alveolar ridge resorbs there is a reduced area of support available for a mandibular complete denture.⁴ The ridge may be complicated further with folds of thin atrophic (non-keratinized) mucosa, which may cause pain and discomfort upon contact with a denture base.¹

The McGill Consensus in 2002⁵ and the York Consensus in 2009⁶ concluded that a two implant-supported mandibular overdenture is the first choice standard of care, as opposed to a conventional mandibular denture for edentulous patients. However, this option may not always be feasible in some cases owing to financial constraints, patient choice or systemic medical conditions. A randomized control trial found that patients with a mandibular ridge equating to Cawood and Howell ridge classification V (Figure 1) and VI preferred mandibular dentures constructed with definitive impressions made using the admix impression technique.⁷ The aim of this paper is to re-visit the ‘admix impression’ technique to aid the practitioner in the construction of a conventional mandibular complete denture in patients with a severely resorbed atrophic mandibular ridge.