Influence of Number of Implants and Attachment Type on Stress Distribution in Mandibular Implant-Retained Overdentures: Finite Element Analysis

Abstract

AIM:This study aimed to compare the stresses generated by using two or four root form dental implants supporting mandibular overdentures that were retained with ball and locator attachments.METHODS:Under ANSYS environment, four 3D finite element models were prepared. These models simulated complete overdentures supported by two or four implants with either ball or locator attachments as a connection mechanism. The models’ components were created by CAD/CAM package then were imported to ANSYS. Load of 100 N was applied at the right premolar/molar region vertically and at an oblique angle of 110° from lingual direction.RESULTS:Within the conditions of this research, in all cases, it was found that cortical and cancellous bone regions were the least to be stressed. Also, the ball attachment produced higher stresses.CONCLUSION:Caps deformation and stresses are negligible in cases of using locator attachment in comparison to ball attachments. This may indicate longer lifetime and less repair/maintenance operations in implant overdentures retained by locator attachments. Although the study revealed that bone was insensitive to a number of implants or attachment type, it may be recommended to use two implants in the canine region than using four, where the locator attachments were found to be better.

Alternative fixation system for implant-retained overdenture: case report

“…Conventional total prostheses have long been considered standard treatment for restoring the stomatognathic system of fully edentulous patients. However, the presence of severe bone resorption, especially of the mandible, generates a series of inconveniences, including lack of retention and stability, difficulty masticatory, and speech and psychosocial problems [4,11,17].…”

“…Among the modalities for implant-supported prostheses, mandibular overdentures have been widely used, since they require a reduced number of implants compared with fixed prostheses, which makes it possible to be indicated in cases of bone resorption, as they are less expensive and are easily hygiene, especially by geriatric patients with limited manual dexterity [4,17].…”

“…For overdentures, retention and stability characteristics are provided by the implants through the fixation system, classified as splinted, such as bar-type, and non-splinted, such as era®, magnetic and O-ring [4]. The shape of the dental arch, space inter-arches, implant placement, ease of adjustment, manual dexterity, and patient agreement will determine the most appropriate system choice [5].…”

Bone height changes around hybrid implants in three implant retained mandibular Overdentures

“…Elanwar et al, 2017 also supported our finding as they recorded that locator attachment showed less Von Mises stress values than the ball attachment with vertical as well as oblique loading conditions in implant-abutment complex, supporting alveolar bone and the resilient caps. (27) They refers this to the low profile design of the locator attachment and to the rotational pivoting character of its abutment that is advocated to lower the rotational center and to potentially reduce the lateral forces. Moreover, using three implants to retain the mandibular overdenture may reduce the stresses on the supporting implants as reported by other researchers (23,24) The insignificant differences of peri-implant bone level between the three studied implants throughout the follow-up periods antagonize the previous concept that the most anteriorly positioned implant provide indirect retention thus increasing the stresses applied on it .…”

Desenvolvimento de dois modelos de mini-implantes e componentes protéticos: correlação da macroestrutura e propriedades mecânicas

“…Além das características do implante, a seleção adequada dos componentes protéticos é essencial para o sucesso do tratamento. No caso das overdentures implato-suportadas, por exemplo, a conexão implante/prótese é realizada por meio de dispositivos esplintados, como barra/clip, utilizado quando a angulação dos implantes é muito discrepante ou não esplintados, que compreendem os sistemas esféricos, tipo bola, magnéticos, ERA®, Locator (EL-ANWAR et al, 2017). Estes, são indicados em situações de dimensão reduzida inter-arcos, sendo vantajosos quanto à higienização, facilidade de confecção e custo reduzido (KOBAYASHI et al, 2014).…”