In-vitro study was carried out to measure the amount of dimensional changes of flexible injection molded (valplast) nylon maxillary complete denture and a rapid heat-polymerized polymethyl methacrylate (PMMA) maxillary complete denture after curing before finishing, and after finishing and polishing. A standard complete denture was constructed and duplication for sixteen dentures was done using duplicating silicone mold then the dentures were divided into two groups. Group A: eight “valplast” flexible dentures processed by injection molded technique. Group B: eight “vertex” rapid (fast) heat curing acrylic resin dentures processed in boiling water for 20 min. Then metallic reference points were placed in the central fossae of the first premolars, and second molars, and immediately below the neck of these teeth in buccal flange. Width, length and cross arch measurements were measured before and after the complete dentures processing. Then, the measurements were made for the dentures by three methods: First method: The measurements from the dentures on casts were obtained using digital caliper capable of measuring up to 0.01 mm. Second method: By using digital camera all dentures were photographed and the dentures’ images were imported into computer where they subjected to special measuring software program. All measurements were obtained both horizontally and vertically. Third method: By taken photographs of the dentures with digital camera then using special software program convert dentures’ images to three-dimension image, then dimensional difference measurements were made by full field 3D comparison of obtained dentures. Also the gap between the stone casts and dentures were measured using the same methods. All collected data were tabulated and subjected to statistical analysis and results show that there was statistically significant difference between the two types of dentures’ materials and when compared with the standard conventional denture; Group B was much closer to it than that of the Group A.