the denture base Location of muscle attachments that arc conducive to denture base stability and retention Class I maxillomandibular relationship. Class II: Moderately compromised This class is distinguished by the continued degradation of the denture‐supporting anatomy. It is also characterised by specific patient management and lifestyle considerations as well as systemic disease interactions. Characteristics include: Residual bone height of 16 to 20mrn measured at the lowest vertical height of the mandible on a panoramic radiograph. Residual ridge morphology that does not show horizontal and vertical movement of the denture base. Location of muscle attachments with limited influence on denture base stability and retention. Class I maxillomandibular relationship. Minor modifiers, psychosocial considerations, mild systemic disease with oral manifestation. Class III: Substantially compromised This classification level is where surgical revision of supporting structures is needed to allow for adequate prosthodontic function. Residual alveolar bone height of 11 to 15mm measured at the least vertical height of the mandible on a panoramic radiograph. Residual ridge morphology has minimum influence to resist horizontal or vertical movement of the denture base. Location of muscle attachments with moderate influence on denture base stability and retention. Class I, II or III maxillomandibular relationship. The conditions that need preprosthetic surgery include: minor soft tissue procedures minor hard tissue procedures including alveoloplasty simple implant placement, no augmentation required multiple extractions leading to complete edentulism for immediate denture placement. Class IV: Severely compromised This classification level depicts the most debilitated edentulous condition. Surgical reconstruction is almost always indicated but cannot always be accomplished because of the patient's health, preferences, dental history, and financial considerations. When surgical revision is not an option, prosthodontic techniques of a specialized nature must be used to achieve an adequate treatment outcome. Residual vertical bone height of 10mm or less measured at the least vertical height of the mandible on a panoramic radiograph. Residual ridge offers no resistance to horizontal or vertical movement. Muscle attachment location that can be expected to have significant influence on denture base stability and retention. Class I, II, or III maxillomandibular relationships. History of paresthesia or dysesthesia. Major conditions requiring preprosthetic surgery complex implant placement, augmentation required surgical correction of dentofacial deformities hard tissue augmentation required major soft tissue revision required, i.e., vestibular extensions with or without soft tissue grafting. Epidemiology Edentulism affects approximately 158 million people globally as of 2010 (2.3% of the population). It is more common in women