الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
A well-constructed two-implant-assisted mandibular overdenture can be a successful treatment option for completely edentulous patients as it helps improving the oral function and patient satisfaction through elimination of the fear of dislodgment during speech or mastication.
Zest anchor locator attachment system was widely and successfully used for implant-assisted overdentures. A new attachment system with metal to metal interface named Titach has been released to be used for implant-assisted overdentures and need to be evaluated and compared to other attachment systems.
The aim of this in-vitro study was to analyse the stress distribution at peri-implant tissues of implant-assisted mandibular overdenture using strain gauges in two different attachment designs (Titach attachment with metal to metal interface and Zest anchor locator attachment with nylon interface). In addition, to measure the retention of mandibular implant-assisted overdentures with each attachment design.
Two implants were inserted in the mandibular epoxy model at the mandibular canine regions bilaterally. Sixteen overdentures were fabricated and divided into two groups according to the type of attachments; group I (n=8) mandibular overdentures with Titach attachment and group II (n=8) mandibular overdentures with locator attachments.
Stress distribution was evaluated at peri-implant tissues using strain gauges. Eight strain gauges were used (four strain gauges were installed at the labial, lingual, mesial and distal aspect of each implant). The wire terminals of the strain gauges were connected to a multichannel strain meter to record the developed strain. A universal testing machine was used for load application 50 N and 100 N. Vertical and oblique (30o, 45o) load was applied in a compression mode through metal rods directed to right and left central fossae of mandibular first molars.
Overdentures’ retention was measured before and after 1000 tension-compression cycles resembling the average number of insertion and removal cycles in one year in vivo. A universal testing machine was used to perform vertical tensile dislodging force to the overdentures. Peak load‐to‐dislodgement was recorded before and after 1000 cycles in each attachment system. Moreover, the percentage change was calculated to indicate the reduction in retention that occured due to usage.
The data was recorded, tabulated and statistically analysed.
Within the limitations of this study, the following conclusions were obtained:
1- There was no statistical significant difference in strain values at the peri-implant tissues between Titach attachment group and Locator attachment group for implant-assisted mandibular overdenture upon application of vertical loading of magnitude 50N and 100 N.
2- Oblique loading showed more strain values compared to vertical loading among both groups but without statistical significant values upon application of reduced load magnitude of 50 N with less oblique load direction of 30o.
3- By increasing the load magnitude with 30o oblique load direction up to 100 N, Titach attachment group showed significant less peri-implant strain values compared to zest anchor locator attachment group.
4- The increase of oblique load direction up to 45o with load magnitude of both 50 N and 100 N showed less strain valueswith favourable stress distribution at the peri-implant tissues among the Titach attachment group compared to zest anchor locator.
5- Titach attachment group showed significant favourable initial and final retentive force compared to zest anchor locator attachment group. However, Locator attachment group showed significant favourable lower percentage change in the retentive force.