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Influence of biomechanical factors associated to implant-supported single crowns and of the bone condition on the bone structure and biomechanical behavior

Author(s):
Germana De Villa Camargos
Total Authors: 1
Document type: Doctoral Thesis
Institution: Universidade Estadual de Campinas. Faculdade de Odontologia de Piracicaba
Defense date:
Examining board members:
Fernanda Faot; Sheila Rodrigues de Sousa Porta; Márcio Zaffalon Casati; Bruno Salles Sotto Maior
Advisor: Altair Antoninha Del Bel Cury
Abstract

Considering the impact of biomechanical environment and bone condition on the prognostic of therapy with dental implants, this study aimed (1) to evaluate the influence of the type of prosthetic abutment associated to different implant connections on bone biomechanical behavior of immediately or delayed loaded implants (Chapter 1); (2) to investigate the effect of single or combined application of high-frequency loading through whole body vibration (WBV) and bisphosphonates (Alendronate, ALN) on the mechanical competence and micro-structure of osteoporotic bone (Chapter 2); (3) to evaluate the impact of combination therapy with WBV and ALN at differing dosages on osteoporotic bone micro-architecture (Chapter 3). In Chapter 1, tridimensional (3D) finite element models comprising a mandible with a single molar implant were created varying the type of prosthetic abutment (UCLA or conical), implant connection (external hexagon, EH or internal hexagon, IH), occlusal loading (axial or oblique), both for immediately or delayed loaded implants. Analysis of variance was used to evaluate the peak of maximum principal stress and strain in cortical and trabecular after applying a 100 N occlusal load. It was observed that the type of prosthetic abutment and implant connection influenced the bone stresses and strains of immediately loaded implants, showing the association of conical abutments with IH implants the lower values of bone stress/strain. In Chapter 2, 34 female Wistar rats were ovariectomized (OVX) or sham-operated (shOVX) and divided into five groups: shOVX, OVX-shamWBV (shWBV, lack of mechanical stimulation), OVX-WBV, ALN-shWBV and ALN-WBV. WBV loading was applied for 10 min/day using 10 consecutive steps of HF loading (130, 135, 140, 145, 150, 130, 135, 140, 145, 150 Hz) at acceleration of 0.3g for 14 days. At the same experimental period, ALN was administered at a dosage of 2 mg/kg/dose, 3x/week. Finite element analysis based on micro-CT was employed to assess bone biomechanical properties (stiffness and strength), relative to trabecular and cortical bone micro-structural parameters. Compared to HF loading, ALN treatment is preferred for improving the compromised mechanical competence of osteoporotic bone. In addition, the association of ALN with HF loading results in an additive effect on bone micro-architecture. In Chapter 3, 56 female Wistar rats OVX or shOVX were divided into seven groups: shOVX, OVX-shWBV, OVX-WBV, ALN(x)-shWBV, ALN(x)-WBV, ALN(y)-shWBV and ALN(y)-WBV. The application of WBV was performed according to the same protocol described previously. Nevertheless, ALN therapy, alone or in combination with WBV, was administered at different dosages [ALN(x): 2mg/kg, conventional dose or ALN(y): 1 mg/kg, reduced dose], 3x/semana. Both mechanical and pharmacological treatments were performed for 6-week experimental period. Micro-CT analyses were performed to evaluate the trabecular bone micro-architecture at the end of experimental period. It was observed that a ALN therapy at a lower concentration when associated to WBV positively impacts the ovariectomy-induced osteoporotic bone, with further improvements in trabecular micro-architecture compared to the conventional monotherapy with ALN. (AU)

FAPESP's process: 11/14001-3 - Biomechanical analysis of implant-supported single screwed protheses under the influence of abutment type, prosthetic platform, occlusion, time of occlusal loading and esthetic recovering material
Grantee:Germana de Villa Camargos
Support type: Scholarships in Brazil - Doctorate