[Change of polished surface contours on mandibular complete denture base in different residual ridge resorption...

To investigate the profile of mandibular denture polished surface in edentulous patients with different residual ridge resorption (RRR) using neutral zone record.

Twenty randomly selected edentulous patients with different category of RRR were investigated, which were divided into three groups according to ridge resorption grade and the relationships between upper and lower jaws: group 1: Class I edentulous patients (n = 6), group 2: Class II edentulous patients (n = 7), group 3: Class III edentulous patients and crossbite jaw relationship (n = 7). All subjects were asked to perform sufficient functional movement with silicon registration material in their mouth to record the shape, which were interpreted as the ideal shape of denture polished surface. Three-dimensional laser scanner was used to record the data of the outline of the maxillary and mandibular ridge and the silicon record of the polished surface. Digital model reconstruction was then conducted on the workstation. Sagittal surface of the model in the cut-in point on first molar and first premolar was made and data of the outline of these surfaces was collected.

Both the buccal and the lingual polished surfaces were concave, straight or slight protuberant and inclined respectively in group 1, 2 and 3. The average angles between the horizontal and the lingual polished surface were (80.40 +/- 3.51) degrees, (90.38 +/- 2.71) degrees and (96.59 +/- 5.00) degrees respectively.

The polished surfaces were changed with different progress of RRR in edentulous patients. It was suggested that the degree of residual ridge resorption and the relationship between upper and lower jaws should be considered when clinicians design the polished surface of denture.