Relationship of neutral zone and alveolar ridge with edentulous period.

OBJECTIVE: To estimate the amount of shift in position of the neutral zone and the centre of alveolar ridge crest in different edentulous periods. STUDY DESIGN: Observational study. PLACE AND DURATION OF STUDY: The study was carried out on edentulous patients reporting in Prosthodontics Department of Lahore Medical and Dental College, Lahore, from August 2006 to December 2008. METHODOLOGY: Patients with edentulous period for at least 6 months exhibiting normal range of maximal mouth opening (40-50 mm) and normal temporomandibular joint movements were included and allocated into two groups, according to period of edentulism. Patient with any intra oral soft tissue or bony pathology and reduced intermaxillary space were excluded. The neutral zone was clinically recorded for all patients with impression compound. The shift between neutral zone and ridge crest in different edentulous periods was analyzed radio graphically and compared statistically. RESULTS: In longer edentulous period (> 2 years), neutral zone was lingually shifted by an average of 1.06 mm in anterior, premolar and molar regions. CONCLUSION: Neutral zone may be lingually shifted in relation to alveolar ridge crest in patients with prolonged edentulous period. This may help in arranging the teeth according to the clinical situation.