الفهرس 
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Abstract
This study was carried out on an educational transparent acrylic resin model of a completely edentulous mandibular arch. Four implants were instilled bilaterally in the canine and first molar areas.7 different impression transfer techniques were recorded to evaluate the effect of these techniques on the three dimensional accuracy of implant analog position in the master cast. These techniques include: 1- Indirect impression transfer technique, 2- direct impression transfer technique without modification of the impression copings, 3- direct impression transfer technique with particle abraded transfer copings, 4-direct impression transfer technique with particle abraded and tray adhesive coated transfer copings, 5-direct impression transfer technique with transfer coping splinted with prefabricated acrylic bar, 6- direct impression transfer technique with transfer copings splinted with dental floss and autopolymerizing acrylic resin bar, 7-direct impression transfer technique with transfer copings splinted with dental floss and autopolymerizing acrylic resin bar then sectioned and reconnected with autopolymerizing acrylic resin.
Each technique was repeated ten times to obtain 70 impressions poured in dental stone after connecting the implant analogs to the transfer copings. All master casts had standard base dimensions.
Implant displacement was measured in three dimensions using three co-ordinates modified measurescope. The measurescope was equipped with computer for direct digitization of the records. Also the eye piece was replaced with dial gauge for measuring the vertical (Z-dimension). Implant displacement was measured directly while the casts were fixed precisely and in a repeatable position in the perspex orientation box which was fixed on the travelling table of the measurescope.
The results of this study revealed that:
(1)Regardless the impression transfer technique, there was a statistically significant displacement of the implant analogs in the three directions X-, Y, Z compared with their positions in the study model.
(2)Regardless the transfer technique, the horizontal analog displacements (X&Y) were greater than the vertical displacement (Z).
(3) Particle abraded transfer copings with adhesive coating produced the least analog displacement in the horizontal (X and Y) and vertical (Z)directions while the use of dental floss and acrylic bar splint of the transfer copings produced the highest analog displacement in the three directions.
(4) Splint of the transfer copings with prefabricated acrylic resin bar produced least displacement of the analogs in the three coordinates compared to splint with dental floss and resin bar (non sectioned and sectioned & reconnected).