Abstract
The main purpose of this work was to construct a clinically valid numerical model of a mandibular Kennedy class I patient rehabilitated with a conventional removable partial denture and another two with implant-assisted removable partial dentures at two different implant locations. The selected patient was classified as ASA I and its mandible geometry reconstruction was performed by the conversion of the Cone-Beam computed Tomography (CBCT) scan raw medical data into a 3D model and subsequent conversion to a CAD file by reverse engineering methods. The soft tissue and removable denture geometries were also included in the CAD model as well as implants, ball attachments and matrix. Moreover, periodontal ligament was modelled by offsetting the mesh of the root surface of each tooth. The finite element results showed that the installation of a dental implant in each of the bilateral edentulous regions helps providing support and retention to the extension bases of the Removable Partial Denture (RPD) and significantly reduces the vertical and anterior-posterior displacements, regardless of its position.
Highlights
IntroductionThe use of clasp-retained removable partial dentures has been a popular option among patients and clinicians to rehabilitate patients with partial edentulism due to the noninvasive nature of the treatment and fair cost-efficiency relationship on the short-term [1,2].on the long-term, this cost-efficiency relationship is disturbed by the limitations of a removable partial denture, which inevitably leads to patient dissatisfaction and a drop of the usage rate, in the case of mandibular distal extension dentures [3,4,5].To reduce some of these limitations, the adjunctive use of dental implants with or without retentive elements have been proposed by several authors [6,7,8,9,10] and are called implant-assisted removable partial dentures
Some studies addressing the finite element analysis of implant-assisted removable partial dentures have been published [17,18,33,34,35,36], the present work is, according to our knowledge, the first non-linear analysis presenting a three-dimensional comparison with conventional extension base removable partial dentures and the first evaluating the effect of implant position on stress and strain on a patient-based 3-D mandibular model
Within the limitations of a static finite element analysis, it is possible to conclude that the loading of conventional Kennedy class I Removable Partial Denture (RPD) leads to significant vertical displacement of the extension bases towards the underlying soft tissues, like a cantilever beam under flexion
Summary
The use of clasp-retained removable partial dentures has been a popular option among patients and clinicians to rehabilitate patients with partial edentulism due to the noninvasive nature of the treatment and fair cost-efficiency relationship on the short-term [1,2].on the long-term, this cost-efficiency relationship is disturbed by the limitations of a removable partial denture, which inevitably leads to patient dissatisfaction and a drop of the usage rate, in the case of mandibular distal extension dentures [3,4,5].To reduce some of these limitations, the adjunctive use of dental implants with or without retentive elements have been proposed by several authors [6,7,8,9,10] and are called implant-assisted removable partial dentures. The clinical guidelines and principles for the design of implant-assisted removable partial dentures proposed by Grossmann et al [12] in patient situations of Kennedy Class I edentulism indicate that per edentulous area, one implant should be inserted as distally as possible to provide maximal support and stability, in the mandible They admit the possibility of placing the implants in a mesial position adjacent to the abutment teeth (natural teeth supporting and retaining a removable partial denture), whenever these are poor to provide support or to avoid unesthetic clasps in maxillary rehabilitations. Two non-clinical studies considered in the work of Grossmann et al
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