Rasha Sami

prerequisite for accurate passively fitted implant-supported restoration. No impression material has
been proven to guarantee a totally accurate implant impression particularly with angled implants.
Aim of the study: Evaluation of the dimensional accuracy of implant level direct impressions
made with either polyether or vinyl poly siloxane impression materials for implants tested with
different angulations.
Materials and methods: Three epoxy resin master models were duplicated from an acrylic
resin typodont model .Each epoxy resin master model received three dummy implants in the sites
of right canine, right second premolar and right second molar with 0° angulation for all implants
in the first model, 15° angulation in the second model and 25° angulation in the third one. A total of
30 implant level direct impressions were made, 10 impressions for each epoxy resin master model,
five were made with polyether impression material (group 1, n=15 ) and the other five were made
with vinyl poly siloxane impression material (group 2, n=15) and impressions were poured with
type IV dental stone. Three referenced inter-abutment distances were measured on each epoxy
resin master model by using a travelling microscope and compared with similar distances on
the stone models following a standardized protocol to calculate the dimensional change and its
percentage. Data were statistically analyzed by means of two way analysis of variance (ANOVA)
followed by Bonferroni’s post-hoc test (P≤ 0.05).
Results: There was statistically non-significant difference in dimensional change and its
percentage between polyether and vinyl poly siloxane groups for all implant angulations at the
three tested inter-abutment distances (P>0.05) . Similar results were found between implants with
0° and 15° angulation (P>0.05) at the three tested inter-abutment distances with both impression
materials examined. Statistically significant difference was observed between implants with 25˚
angulation and those with 0° as well as 15° angulations (p<0.05) in the three tested inter-abutment
distances with polyether and vinyl polysiloxane, where the 25˚ implant angulation showed the
greatest dimensional change and percentage of dimensional change among the tested angulations
with both impression materials