الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
This in vitro study was conducted to evaluate strain around labially inclined implants retaining mandibular overdentures with TiSi attachments after applying verticalcentral loading and unilateral loading using universal testing machine and strain meter to record the measurements.
Three ready made edentulous mandibular Epoxy models were used Foreach model, about1.5-2 mm thickness of autopolymerized resilient silicone soft lining material was used to simulate resilient edentulous ridge mucosa.
Using CAD CAM Surgical guides and surgical drill tools, Two dummy implants were inserted in each model in the canine regions using CAD CAM surgical guides with the following degrees of labial inclinations: group A (control); 0°, group B; 17.5°and group C; 35°.
Thirty Experimental mandibular overdentures were constructed over the models and connected to the models with Ti Si attachments with retentions Sil 400 g / 4 Newton and retentions Sil 600 g / 6 Newton.
Four strain gauges were boundedaround each implantmesial (M), distal (D), labial (B) and lingual (L), using cyanoacrylate adhesive. Universal testing machine was used to measurethe micro-strain values around the implants supported mandibular overdenture,central and lateral load of crosshead speed of the universal testing machine wasadjusted at 60N to mimic occlusal force. Load transferred (centrally and unilaterally right and left) to the epoxy model through custom –made metal bar with occlusal imprints.
The free ends of the wires of the strain gauges were attached to multi-channel strain meter mesial (M), distal (D), labial (B) and lingual (L) for each implant . Measurements were recorded by strain –meter that connected to universal testing machine and compared between thethree groups.
Once the load was applied, the obtained microstrain readings were recorded by the strain meter which was connected to a personal computer with aiding of special software to allow for viewing the obtained microstrain readings.
All measurements were repeated 5 times allowing at least 5 minutes for recovery and to allow for heat dissipation, and the meansof recorded microstrain values was subjected to statistical analysis. For thethree groups, the same steps were repeated.
During both central and unilateral loading, the loading device was adjusted to apply loads 60Newtons and software of strain meter was set to record the microstrain readings at the desired loading point.
The microstrain was recorded at the mesial, distal, labialand lingual sides of the implant.
The results of this invitro study weresummarised as follows:
1- In all groups’ 0°, 17.5° and 35°labially inclined implants under central and unilateral loading, the highest microstrain was recorded at the lingual and mesial sides of the implants. While the lowest microstrain was recorded at distal and labial sides of the implants.
2- In comparing the three groups 0°, 17.5° and 35°labially inclined implants,there is significant difference was found with central loading using retention sil 400g /4N and 600g/6N, while with unilateral loading significant increase in microstrain was recorded with labially inclined implants.
3- In comparing the three groups during central and unilateral loading with the different Ti Si ( 400 g/ 4 N and 600g/6 N ) .The highest microstrain was recorded with retention sil 600 g/6 N