الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
In vitro study was conducted to assess the dimensional accuracy regarding trueness and precision of Vinyl siloxane ether (VSXE) and Polyvinylsiloxane (PVS) impression materials using two different impression techniques.
In vivo study was conducted to evaluate peri-implant soft tissue changes - modified gingival index, modified plaque index and peri-implant probing depth- of two implants retained mandibular overdenture when using two different materials of bar; Poly-etheretherketone (PEEK) and Cobalt chromium.
In addition, assessment of patient satisfaction using oral health impact profile (OHIP-14) was done for all patients.Within the limitations of in vitro and in vivo study, it was concluded that:
1- In terms of trueness and precision, the best results were observed with VSXE impression material using an open tray technique, while the worst outcomes were observed with PVS impression material using a closed tray technique. Moreover, moderate trueness and precision results were observed with VSXE impression material using a closed tray technique, and PVS impression material using an open tray technique.
2- Both Co-Cr and PEEK bar groups can be considered viable and successful treatment options for implant-supported overdentures with respect to OHIP scores and peri-implant parameters. Additionally, PEEK material may have the potential to enhance gingival health parameters, thereby contributing to an improved overall quality of life related to oral health.The current in vitro study has several limitations, and therefore, the results should be interpreted with caution. For instance, the impression materials were tested under dry conditions without the use of disinfection solutions, which may not reflect the clinical scenario accurately. Future investigations should evaluate the effect of saliva or blood on the accuracy and properties of the impression materials.
Another limitation is that the study did not analyze nonparallel implant conditions. Further studies are needed to overcome these limitations and provide more comprehensive information on the performance and properties of these materials.
It could be recommended to utilize larger sample sizes in future research to validate these outcomes comprehensively. This will provide a more comprehensive understanding of how various bar materials impact peri-implant soft tissues in implant-supported overdentures. Furthermore, additional longitudinal studies should examine the peri-implant soft tissue health over an extended period of time.