الفهرس 
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Abstract
The study was carried to mechanically assess (using stress strain analysis) and biologically assess (bone height change using CBCT) and evaluate the effect of immediate loading on Straumann’s SLActive implant with nova lock attachment versus SLActive implant with locator attachment.
Twelve completely edentulous patients were selected from the outpatient clinic of oral and maxillofacial prosthodontic department, faculty of dentistry Ain Shams University to participate in this study.
The study protocol was reviewed and approved by the research ethics committee, faculty of dentistry, Ain Shams university.
Patients were precisely selected and thoroughly examined in an attempt to reduce human variables and eliminate any factor that might adversely affect the results of this study.
Patients were rehabilitated by mucosa supported maxillary complete denture and two implants retained mandibular overdenture following immediate loading with one SLActive implant with nova loc while the other was SLActive with locator attachment in split mouth fashion.
Standard clinical and laboratory techniques were followed for denture construction for all patients. Patients were frequently recalled for inspection and post insertion adjustments. Follow up visits were scheduled at time of implant loading, six and twelve months after loading for making radiographic records required to evaluate the implant marginal bone height changes. Marginal bone height change around the implants was evaluated using the linear measurement system supplied by the CBCT.
Results obtained from this study showed statistically significant decrease in peri-implant bone height for the SLActive with locator at the end of the one year follow up period than SLActive with nova loc.
While for invitro study:
The study was conducted on computer generated three dimensional models simulating a completely edentulous lower arch with two implants inserted at the inter foraminal region retaining mandibular over denture prosthesis The sample size included 10 identical experimental models (5models/group).
Two model groups were constructed according to:
• Model I: two implants retaining mandibular overdenture made from acrylic resin (poly methyl methacrylate) attached to the implants analogues by nova loc with peek insert & matrix.
• Model II: two implants retaining mandibular overdenture made from acrylic resin (poly methyl methacrylate) attached to the implants analogues by locator with same retaining force of 1200 gm and geometric height of model I nova loc.
With grooves designed with a flat plane parallel to the long axis of the implants and separated by 1 mm from the implant beds at the mesial, distal aspect for strain gauges installment.
The load was applied both unilaterally and bilaterally to simulate all the patients chewing patterns.
When comparing between the two groups during bilateral loading, it was found that the implants of the locator attachment group II received higher micro-strain values than the implants in the nova loc attachment group I.