Prosthetic rehabilitation of acquired mandibular defects by neutral zone concept

Objectives: The objective of this case report is to asses the application of neutral zone concept in a patient with acquired mandibular defect for the fabrication of stable removable partial denture.

Methods: A patient with left side marginal mandibular resection defect following radiotherapy (squamous cell carcinoma of the jaw) came to the prosthodontic department of FMH College of Medicine and Dentistry for prosthesis. The surgery resulted in loss of teeth and alveolar bone support from the lower jaw (tooth no 25 to 32). An alginate impression supported by thermoplastic compound in the defect area was taken for the study model. Following surveying of the study cast and mouth preparations done accordingly, a framework was cast with nail head projections occlusally above the defect area to support the material for recording the neutral zone. After framework trial, phonetic and swallowing neutral zone was recorded with a thermoplastic impression compound followed by incremental additions of tissue conditioner. Then putty indexes were made and the tooth setup completed. The polished surfaces were determined using piezography.

Results: The prosthesis was stable with the biscuit test at insertion appointment as well as at the follow up appointments
Conclusions: The neutral zone technique is employed in complete denture construction for denture stability. This case report describes the application of neutral zone in a removable partial denture patient who had undergone marginal mandibular resection to improve upon the denture stability. The merit of this technique is paramount in denture construction when socioeconomic factors and post surgical morbidity do not allow other methods of rehabilitation.