الفهرس 
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Abstract
Ten patients were selected from the out-patient clinic of Prosthodontic Department, Faculty of Dentistry, Ain Shams University to compare between the retention and adaptation of complete denture bases fabricated with conventional technique and CAD/CAM techniques (additive and subtractive).
For each patient three upper denture bases were constructed. Thus three groups were defined according to the technique of construction of the denture base.
group I: Denture bases were constructed by the conventional technique using heat cured resin.
group II: Denture bases were digitally designed and milled from prepolymerized blocks of PMMA.
group III: Denture bases were digitally designed and fabricated by rapid prototyping (3D printing) technique.
The retention of each denture base was evaluated using digital force guage while adaptation was evaluated using geomagic control x software. It compared between the fitting surface of the denture base and the surface of its corresponding cast and three values were recorded for each case: the average value of negative deviation of the denture base surface from the cast surface (gap areas), the average value of positive deviation of the denture base surface from the cast surface (pressure areas), and the average value of overall deviation of the denture base surface from the cast surface.
Data was statistically analyzed and showed that the retention of group II was significantly higher than group I. However, there was no significant difference between group I and group III and between group II and group III.
Regarding the results of adaptation it was found that the greatest gap distance was found with group III then group I and the smallest gap distance was found with group II. There was a statistically significant difference between all groups.
The largest pressure was found with group III then group I and the smallest pressure was found with group II. However there was a statistically significant difference only between group III and group II while there was a statistically non-significant difference between group I and group II and between group I and group III.
The least deviation (best adaptation) was found in group II followed by group III and the largest deviation was found in group I.