Fem and Von Mises analysis of OSSTEM ® dental implant structural components: evaluation of different direction dynamic loads

Abstract PURPOSE: The objective of this investigation is to study prosthodontics and internal components resistance to the masticatory stress and considering different force directions by using Finite Element Method analysis (FEM). The structural materials of the components are usually Titanium alloy grade 4 or 5 and thus, guarantee the integration of the fixture in the bone due to the osteointegration phenomena. Even if the long-term dental implant survival rate is easy to be obtained and confirmed by numerous researches, the related clinical success, due to the alteration of the mechanical and prosthodontics components is still controversial. METHODS: By applying engineering systems of investigations like FEM and Von Mises analyses, it has been investigated how dental implant material was held against the masticatory strength during the dynamic masticatory cycles. A three-dimensional system involved fixture, abutment and the connection screws, which were created and analyzed. The elastic features of the materials used in the study were taken from recent literature data. RESULTS: Data revealed a different response for both types of devices, although implant neck and dental abutment showed better results for all conditions of loading while the abutment screw represented aweak point of the system. CONCLUSION: The data of this virtual model showed all the features of different prosthetic retention systems under the masticatory load. Clinicians should find better prosthetic balance in order to better distribute the stress over the component and to guarantee patients' clinical long-term results

The use of different adhesive filling material and mass combinations to restore class II cavities under loading and shrinkage effects: a 3D-FEA

3D tooth models were virtually restored: flowable composite resin + bulk-fill composite (A), glass ionomer cement + bulk-fill composite (B) or adhesive + bulk-fill composite (C). Polymerization shrinkage and masticatory loads were simulated. All models exhibited the highest stress concentration at the enamel–restoration interfaces. A and C showed similar pattern with lower magnitude in A in comparison to C. B showed lower stress in dentine and C the highest cusps displacement. The use of glass ionomer cement or flowable composite resin in combination with a bulk-fill composite improved the biomechanical behavior of deep class II MO cavities

The use of different adhesive filling material and mass combinations to restore class II cavities under loading and shrinkage effects: a 3D-FEA

3D tooth models were virtually restored: flowable composite resin + bulk-fill composite (A), glass ionomer cement + bulk-fill composite (B) or adhesive + bulk-fill composite (C). Polymerization shrinkage and masticatory loads were simulated. All models exhibited the highest stress concentration at the enamel-restoration interfaces. A and C showed similar pattern with lower magnitude in A in comparison to C. B showed lower stress in dentine and C the highest cusps displacement. The use of glass ionomer cement or flowable composite resin in combination with a bulk-fill composite improved the biomechanical behavior of deep class II MO cavities

Direct resin composite restoration of endodontically-treated permanent molars in adolescents: bite force and patient-specific finite element analysis

Objective: To evaluate the influence of three levels of dental structure loss on stress distribution and bite load in root canal-treated young molar teeth that were filled with bulk-fill resin composite, using finite element analysis (FEA) to predict clinical failure. Methodology: Three first mandibular molars with extensive caries lesions were selected in teenager patients. The habitual occlusion bite force was measured using gnathodynamometer before and after endodontic/restoration procedures. The recorded bite forces were used as input for patient-specific FEA models, generated from cone-beam computed tomographic (CT) scans of the teeth before and after treatment. Loads were simulated using the contact loading of the antagonist molars selected based on the CT scans and clinical evaluation. Pre and post treatment bite forces (N) in the 3 patients were 30.1/136.6, 34.3/133.4, and 47.9/124.1. Results: Bite force increased 260% (from 36.7±11.6 to 131.9±17.8 N) after endodontic and direct restoration. Before endodontic intervention, the stress concentration was located in coronal tooth structure; after rehabilitation, the stresses were located in root dentin, regardless of the level of tooth structure loss. The bite force used on molar teeth after pulp removal during endodontic treatment resulted in high stress concentrations in weakened tooth areas and at the furcation. Conclusion: Extensive caries negatively affected the bite force. After pulp removal and endodontic treatment, stress and strain concentrations were higher in the weakened dental structure. Root canal treatment associated with direct resin composite restorative procedure could restore the stress-strain conditions in permanent young molar teeth

Influence of adhesive technique and thermomechanical fatigue on the fracture strength of minimally invasive CAD/CAM occlusal veneers

With the development of new CAD/CAM restorative dental materials, limited data regarding their survival rate and fracture strength are available when they are used as occlusal veneers. Therfore, These materials could be evaluated under conditions similar to those of the oral environment before being recommended for clinical use . For that reason, the influence of thermomechanical fatigue and adhesive bonding technique (etch-and-rinse and self-etching ) on the survivability and fracture strength for four different CAD/CAM materials were evaluated in this study

Planejamento digital e cirurgia guiada em reabilitação oral: relatório de caso

Digital planning of the prosthesis associated with surgical planning increased predictability, since surgical guides indicate the best place for implant installation, thus reducing the number of complications, and the CAD/CAM system provides predictability in the preparation of final restorations, according to the procedure previously planned. Our study reported a digital workflow used for the guided installation of two dental implants in regions 14 and 16, extraction of tooth 15 and installation of a fixed prothesis over implants. After anamnesis and clinical evaluation, intra- and extra-oral photographs of the patient were performed, molding the upper arch with polyvinylsiloxane (2-step putty/light-body technique) and requesting computed tomography. The plaster model obtained was sent to the laboratory and scanned. The generated file (STL) was used to create a diagnostic wax-up that was aligned to the tomography (in DICOM format), enabling the three-dimensional planning of the implants, which generated a partial printed surgical guide after approval of the dentist. After six months, the patient received the provisional fixed prosthesis printed in PMMA (polymethylmethacrylate) on an intermediate in PEEK (polyetheretherketone) aiming to condition an emergency profile to receive a definitive prosthesis two months later, with zirconia-milled infrastructure on a ti-base. The correct understanding of the operator about the steps of the digital workflow (diagnosis, prosthetic planning, surgical planning, guide preparation, temporary and final restorations) gives the operator improved predictability at the time of surgery as well as satisfactory aesthetic and functional result of definitive restorations.Planejamento digital de prótese associada a planejamento cirúrgico aumenta a previsibilidade devido às guias cirúrgicas que indicam o melhor local para instalação do implante, reduzindo o número de complicações, e o sistema CAD/CAM permite previsibilidade ao preparar as restaurações finais, de acordo com o procedimento planejado anteriormente. Nosso estudo relata um fluxo de trabalho digital usado para a instalação guiada de dois implantes dentários nas regiões 14 e 16, extração do dente 15 e instalação de prótese fixa no lugar de implantes. Após anamnese e avaliação clínica, fotografias intra e extraorais do paciente foram tiradas, moldando o arco superior usando polivinilsiloxano (técnicas da dupla mistura e reembasamento) e solicitando tomografia computadorizada. O modelo de gesso obtido foi enviado para o laboratório e escaneado. O arquivo gerado (STL) foi usado para criar um diagnostic wax-up alinhado à tomografia (em formato DICOM), permitindo o planejamento tridimensional dos implantes, o que gerou uma guia cirúrgica parcialmente impressa após aprovação pelo dentista. Após seis meses, o paciente recebeu uma prótese fixa provisória impressa com PMMA (polimetilmetacrilato) em um intermediário em PEEK (Poli(éter-éter-cetona)) para condicionar um perfil emergencial e receber uma prótese definitiva dois meses depois, incluindo infraestrutura de zircônia moída em uma base TI. O entendimento adequado do operador a respeito dos passos envolvidos no fluxo de trabalho digital (diagnóstico, planejamento de prótese, planejamento cirúrgico, preparação da guia, restaurações temporárias e finais) forneceu ao operador maior previsibilidade no momento da cirurgia e um resultado estético e funcional satisfatório para as restaurações definitivas

Classic Reviews from Past Comprehensive Review Courses in Prosthodontics

https://deepblue.lib.umich.edu/bitstream/2027.42/154049/1/classic_reviews-vol1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154049/2/classic_reviews-vol2.pdfDescription of classic_reviews-vol1.pdf : Volume 1Description of classic_reviews-vol2.pdf : Volume

Long-term fracture load of all-ceramic crowns : effects of veneering ceramic thickness, application techniques, and cooling protocol

To evaluate, in vitro, the effects of the cooling protocol, application technique, and veneering ceramic thickness on the fracture resistance of ceramic crowns with Y-TZP frameworks. 80 frameworks were made from zirconia by the CAD/CAM technique and divided into 8 groups (n = 10) according to the factors: ?application technique? (stratified-L and pressed -P), ?thickness? (1 mm and 2 mm), and ?cooling protocol? (slow-S and fast-F) of the feldspathic veneering ceramic. After, all crowns were cemented over G10 preparations with resin cement (Panavia F, Kuraray), mechanically cycled (2x106 cycles, 200 N, 3Hz), and subjected to the axial compression resistance test (0.5 mm/min, 10 kN). The data (N) underwent descriptive statistical analysis by 3-way ANOVA and Tukey?s test (5%). Fracture analysis was performed to determine the possible origin of failure. The factors ?cooling protocol? (P=0.0058) and ?application? technique (P=0.0001) influenced the fracture resistance of the crowns. For pressed veneer technique, the P2S (4608.9±464.5). A presented significantly higher results than that P2F(3621.1±523.0)BCD (Tukey?s test). For the stratified technique, this difference was not observed (P>0.05). The thickness of the veneering ceramic was not significant regardless of the cooling protocol and technique (P>0.05). The predominant failure mode was chipping of the ceramic veneer originating in the subsurface. The pressed technique, used with a slow-cooling protocol, leads to the best outcome for the veneering of all-ceramic crowns

Finite element analysis on the optimal material choice and cavity design parameters for MOD inlays exposed to different force vectors and magnitudes

WOS: 000386328700002This simulation study evaluated the effect of three different inlay materials (composite, glass ceramic, zirconia), cavity design parameters (isthmus width and depth) and different force vectors and magnitudes on the stress distribution within mesio-occlusal-distal (MOD) inlays and the remaining enamel and dentin. The mechanical performance of inlays was evaluated using 3-D finite element analysis (FEA) method. Three different restoration materials and hard tissues of the restored tooth with different cavity depth (2-5mm) and width (2-4mm) were exposed to occlusal loading with different magnitudes from 10 to 130kg at varying angles between 0 degrees and 15 degrees. The maximum von Mises stresses were calculated for the inlays, tooth structure and bonded surfaces. Response Surface Optimization method was implemented into the finite element software package in order to design cavity shapes with more favourable interfacial stresses for bonded restorations under occlusal loading. Teeth restored with resin composite exhibited the highest von Mises Stress, followed by glass ceramic and zirconia. The increase in isthmus width decreased interfacial shear stresses in zirconia MOD inlay but the increase in cavity depth did not change the stress levels for all three materials. According to mechanical safety factor, inlay and tooth structure remained within the mechanical limits in three parameters (material, magnitude of force, cavity shape) but negatively affected by the force vector