الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
This study was conducted to evaluate implant-bone interface of two implant systems with regularly patterned and randomly rough surface to retain mandibular overdentures.
Nine completely edentulous male patients were included in this study. Each patient received a maxillary conventional complete denture and a mandibular overdenture retained by two implants. One implant was surface treated by laser micro grooving to produce surface micro grooves of regular depth and distribution (LMG). The other implant was surface treated by resorbable blast texturing of Tricalcium phosphate to produce randomly roughened surface (RBT).
Ball abutments were used to functionally load the implants. All implants were delayed loaded after three months of surgery and dentures were attached to the implants by direct clinical pickup technique.
Evaluation of the implant retained overdenture was performed immediately after loading (0-month) at base line, and repeated after 1, 3, 6, and 12 months of functional loading.
Maximum axial bite force applied on the implants was recorded clinically at each follow up interval using a bite force sensor (Flexiforce sensor) and a reader set up. The setup was programmed to convert the load applied on the sensors at the right and left sides of the mandible, into recordable measures in Newtons seen on LCD screen.
Radiographic evaluation was performed at each follow up interval on 3D CT images regarding marginal bone level and perimplant bone density. Marginal bone level was measured in millimeters from the implant shoulder to the first point of bone contact on the implant surfaces. Perimplant bone density was measured at three horizontal zones (coronal, middle and apical) along implant surfaces.
3D finite element models (FEM) of each implant assembly, its surrounding alveolar bone, the overlying mucosa, and overdenture were developed for stress analysis in the implant retained overdenture.
Results of this study indicated insignificant difference between right and left sides in bite force recording at all follow up intervals, but significant increase in bite force values for both sides from base line to the end of the follow up period.
Regarding marginal bone level at implant-bone interface of LMG and RBT implants, results showed that changes in marginal bone levels were significant for both implants throughout the study from base line to one year of follow up. Changes for both implants were within the accepted limits reported in literature.
Perimplant bone density results, showed increase in bone density for both implants throughout the study intervals, which was significant at the coronal, middle, and apical zones of LMG implant and at the middle zone of RBT implant.
FEM analysis of stress distribution around LMG implant and RBT implant retaining a mandibular over denture showed highest maximum Von Mises stress at the crestal bone around the neck of both implant systems, in the fitting surface of the dentures surrounding the neck of the implants, and at neck of ball abutment where the ball engaged the housing undercut groove.
Within the limits of the present study it is concluded that:
• The prosthetic rehabilitation of edentulous patients with mandibular retained overdenture improved oral function and enhanced patient satisfaction as was observed from the increase in bite force values from base line to one year follow up period.
• 3D CT radiographic scanning of dental implants provided useful and predictable tool to evaluate bone quantity and quality, as well as accurate measurement of MBH and PBD around the implants.
• LMG implant illustrated lesser amount of MBH and higher PBD values in comparison to RBT implant, especially at initial stages of functional loading.
• Based on the radiographic evaluation, higher amounts of changes were recorded at implant-bone interface around LMG implant indicating increased activity of bone adjacent to the implant surface and higher degrees of bone remodeling in response to functional loading.
• FEM analysis revealed that stress are concentrated at the crestal bone and neck region of both implants with less stress recorded related to the LMG implants.