Hina Zafar Raja, Muhammad Nasir Saleem.
Effect of previous denture wearing on neutral zone morphologies.
Pak Oral Dental J Jan ;34(4):752-5.

Objective was to evaluate the effect of previous denture wearing on the morphology of phonetic and swallowing neutral zones recorded with a impression compound. It was an observational study. The study was carried out on edentulous patients reporting in Prosthodontic Department of Institute of Dentistry, CMH, Lahore Medical College, Lahore, from May 2013 to August 2013. 18 patients with a minimum edentulous period of 6 months exhibiting normal range of maximal mouth opening (40- 50mm) and normal temporomandibular joint movements were included. Patients with a history of smoking and tobacco use, pendulous residual ridge, retracted tongue position, any neuromuscular problem, or psychological disturbances, were excluded from the study. Amongst them 7 were previously denture wearers while 11 have never worn a denture. Swallowing and phonetic neutral zones were recorded with impression compound. The outlines were drawn on graph sheets and measured. Buccal and lingual deviation of phonetic and swallowing neutral zones were compared statistically, in previous denture and non denture wearers. Generally, the differences in morphologies of phonetic and swallowing neutral zones were not statistically significant in previously denture wearers and non denture wearers except on lingual aspect of mandibular molar area. The influence of previous denture on the comparative shapes of phonetic and swallowing neutral zone may not be prominent. The muscle activity does not significantly differ in previous denture and non denture wearers. However complete dentures for subject with no history of previous dentures can be made with neutral zone technique for improved stability.

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