3-D in vivo force measurements on mandibular implants supporting overdentures. A comparative study

Area of Science:

• Biomaterials and Biomechanics
• Dental Implantology
• Prosthodontics

Background:

• Dental implants supporting overdentures require precise force transmission analysis.
• Understanding force distribution is crucial for long-term implant success and patient comfort.
• Various anchorage systems exist, each with potential biomechanical implications.

Purpose of the Study:

• To quantify in vivo 3-dimensional force transmission onto implants under different overdenture anchorage systems.
• To compare force distribution patterns among U-shaped bars, clip-bars, and single telescopes.
• To evaluate the influence of different functional loads (biting, chewing) on implant forces.

Main Methods:

• Utilized in vivo piezoelectric transducers mounted directly on implants to measure 3D forces.
• Tested three overdenture anchorage types: U-shaped bar, round clip-bar, and single telescopes.
• Recorded forces during maximum centric occlusion biting, bite plate loading, grinding, and chewing.

Main Results:

• Vertical forces varied significantly with anchorage type and functional load.
• Transverse forces ranged from 10-50% of vertical forces.
• Telescopes showed higher vertical forces than bars during bite plate loading (p < 0.01).
• Chewing and grinding produced lower vertical forces than maximum biting.
• Transverse forces during chewing/grinding were substantial (50-100% of vertical).
• Rigid bars demonstrated superior load sharing and stress distribution.

Conclusions:

• No single overdenture anchorage system demonstrated clear superiority for all force components.
• Rigid bar systems effectively distribute loads and stresses across implants.
• Understanding force transmission dynamics is key for selecting optimal overdenture support mechanisms.