The clinical significance of the relations between maxillar and mandibular edentulous residual jaws

Objectives: Loss of all natural teeth results in bone remodeling of the alveolar process and part of the basal bone. In edentulous patients the residual arches provide the vital tissues on which denture bases and the artificial teeth are placed. Modern technological advances allow the practitioner to use osseointegrated implants as a mean of retention for the selected type of prosthetic restoration. The establishment of the best place to furnish the foundation for these implants in the residual arches is of high importance. The objective of this work was to examine characteristics of edentulous arches, the relations between occluding jaws and their clinical meaning in terms of prosthetic treatment planning.
Methods: Two hundred and twelve stone casts mounted in centric relation, from one hundred and six edentulous patients were examined and measured. The measurements included the length of the maxillar and mandibular edentulous casts, the width of the maxillar and mandibular arch, and the interjaw distances and relations at the anterior and posterior regions.
Results: A positive and significant correlation was found between maxillary width and length (p<0.05). A positive non-significant correlation was found between mandibular width and length. Higher width of maxilla and mandibular were found among males as compared to females (p<0.001). The vertical interjaw distances varied from 9 to 28mm in both anterior and posterior regions. The horizontal interjaw distances and relations varied widely in both anterior and posterior regions: 11 to -8mm at incisor region[J1] ; two major groups were observed at posterior region- bilateral symmetrical relations (60.3%), and bilateral asymmetrical relations (39.5%)
Conclusions: There is a large disparity in sizes and shapes of edentulous arches and high variation in the spatial interarch characteristics. Prior to implant placement and rehabilitation of edentulous arches it is essential to analyze the anatomy and the relations of the occluding residual ridges in order to achieve prosthetic favorable results.