Comparison of stress induced in mandible around an implant-supported overdenture with locator attachment and telescopic crowns – a finite element analysis

Abstract

Introduction. One of the principle factors for the success of implant supported/retained overdentures (IOs) is the manner in which the stresses are transferred to the surrounding bone. Hence, the aim of the present study is to compare the stress induced in the mandible around IOs, using two different attachment systems, locator and telescopic.
 Methods. 3D finite element models were prepared using Pro/ENGINEER or PTC Creo to simulate 4 clinical situations: IOs using two different attachment systems, locator and telescopic, with and without splinting. A vertical compressive load of 35N was directed toward the central fossa in the molar region of each overdenture. Non-linear static contact analysis was carried out to determine the stress distribution in various components of IOs. Then, the models were analyzed by a finite element program ABAQUS, and displayed using Von Mises stress patterns.
 Results. The contact stress values developed on the implant and attachment components were lower with locator attachment, in both splinted and non-splinted models. On the other hand, the stress distribution to the cortical bone was more with non-splinted/splinted locator attachments (3.73/4.12 Mega Pascals) when compared to the non-splinted/splinted telescopic attachments (2.66/3.7 Mega Pascals). The stresses in all the components of overdenture were greater with the splinted model compared to non-splinted, in both the attachment systems. 
 Conclusion. The locator attachment might demonstrate superior clinical performance, as the stresses on implant and attachment components were less compared to telescopic. Non-splinted model showed better results in both the attachment types.

Evaluation of Bone Height Changes in Three Implants Retained Mandibular Overdenture Using Three Different Attachment Design. A Randomized clinical trial.

“…Similarly, because of the cantilever effect of splinted bar, the deflection was of greater value causing high stresses at the level of the contact zone of the abutment, implant and screw. 53 In the present trial the ball and locator attachment are considered as unsplinted attachment, while for the telescope attachment it exerted a secondary splinting effect. Results of the present study showed that the ball attachment has recorded the greatest bone height changes when compared to the locator and telescope attachment.…”

Finite Element Study of Stress Distribution with Tooth-Supported Mandibular Overdenture Retained by Ball Attachments or Resilient Telescopic Crowns

“…41 This agreed with many studies. 1,41,42 Ball attachments transferred less stress to the canines and the cortical alveolar bone of the canines than resilient telescopic crowns, but transferred more stress to the cortical bone of alveolar process at the distal end of the overdenture. Ball attachment allows free movement in several directions while resilient telescopic crowns allow free vertical movement.…”

“…6 Telescopic overdenture is a prosthesis that includes a primary crown cemented to the abutment and a secondary crown attached to the prosthesis and fits on the primary crown. 1,7 Three types of telescopic crowns have been described: the parallel-walled crowns, the conical crowns with tapered design, and the resilient crowns with clearance fit. 3,8 Clearance fit means free space between primary and secondary crowns.…”

“…This selection may be affected by available vertical and horizontal space, cost effectiveness, and skills of dentist. 1,3,4 Ball and socket attachment is used widely. This system can be applied with root and implant-supported prostheses.…”

Comparison of stud and telescopic crown attachments for mini-implant retained mandibular complete overdentures

“…reported that, although four mini-implants have been recommended as an alternative treatment for the edentulous patients, no published evidence indicated that this option is better than the use of two. The telescopic copings for group II were fabricated according to the resilient design, to allow a slight movement of the overdenture to avoid stresses on the implants (19) .…”