The biomechanical behavior of single crown implant-supported prosthesis with different types of connections and occlusal loads: Photoelastic and strain gauge analysis

The aim of the study was to evaluate the biomechanical behavior, through photoelastic (PA) and strain gauge analysis (SA), of single crown implant-supported prosthesis with different implant connections (external hexagon (EH), Morse taper (MT), internal Morse hexagon (IMH), Morse taper hexagon (MTH), and frictional Morse taper (FMT)) and different occlusal loads (axial and oblique (45°)). The data were submitted to ANOVA and Tukey's test (α = 0,05). By photoelasticity, regarding axial load, EH produced more high-intensity fringes (2.784 kPa) than the other connections. For the oblique load, all connections generated the same high-intensity fringes (3.480 kPa), except by MT group, that produced the same amount as axial load (2.088 kPa). For the strain gauge analysis, for the axial load, EH showed the highest microstrains value (158,76) and lowets for MT (59,88). For all other groups, oblique load produced higher microstrains values than axial load. For the oblique load, MT showed the lowest microstrains value (88.79), followed by FMT (391,43), EH (468,47) and IMH (507,65). MTH presented the highest value (621,25) compared to all groups (P <0.05). When comparing both loads of the same connection system, only MT showed similar values (P <0.05). It was possible to conclude that the different connection systems tested directly influenced the stress distribution at both loads. The implants with internal connection present less stress distribution when submitted to axial load than the EH group. However, when the oblique load was applied, all connections presented higher values of stress distribution, except for the MT group.

Finite Element Analysis of Dental Implants with Zirconia Crown Restorations: Conventional Cement-Retained vs. Cementless Screw-Retained

The present study was designed to compare the stress distributions in two restoration types of implants and the surrounding bone. The first restoration type was a conventional cement-retained zirconia crown, and the second was a novel cementless screw-retained zirconia crown with a base abutment. A three-dimensional finite element method was used to model the implants, restorations, and supporting bone. A comparative study of the two implants was performed under two masticatory loads: a vertical load of 100 N and a 30-degree oblique load of 100 N. Under both loading conditions, the maximum von Mises stress and strain values in the implant and supporting bone were higher in the conventional cement-retained restoration model than in the cementless screw-retained model. In terms of stress distribution, the cementless screw-retained zirconia crown with base abutment may be considered a superior restoration option compared to the conventional cement-retained zirconia crown.

Stresses in lithium disilicate crowns and zirconia implants in patients with bruxism: An in silico study

The aim of this study was to analyze by finite element analysis the influence of the use occlusal splints in rehabilitation with zirconia implant under oblique and vertical masticatory loads. Four models were developed to simulate a clinical of absence of a premolar (element 45) replaced by zirconia implant and lithium disilicate crown. Four groups were created, SP-V without occlusal splint and vertical load; CP-V with occlusal splint and vertical load; SP-O without occlusal splint and oblique load; CP-O with occlusal splint and oblique load. The four models were built using a software (SolidWorks, SolidWorks Corporation). A load of 300N to 45º (oblique) and 90º (vertical) applied to the long axis of the whole structure. The maximum principal stress (tensile) and minimum principal stress (compression), as well as the total deformation in the implant, occlusal splint, crown and bone tissue were evaluated quantitatively and qualitatively. The CP-V and CP-O groups presented the lowest stress intensities, which were homogeneously distributed in all structures analyzed. On other hand, SP-V and SP-O groups presented highest stress distributed in a heterogeneous way. Groups with occlusal splint (CP-V and CP-O) also showed lower deformation than groups without occlusal splint (SP-V and SP-O). It´s concluded the use of occlusal splint minimizes the stresses and deformation promoted by oblique and vertical occlusal loads of up 300N in implanted lithium disilicate crown supported by zirconia implants.

Crashworthiness Analysis of Octagonal-Inner Double Tube with different thickness under Off-Axis Oblique Load

The crash tube is one of the important parts to reduce the effects of accidents. The design of crash tube only watches the frontal crash, but oblique crash might affect the passengers. Besides, Lack of oblique-loading researches in crashworthiness becomes causes to analyze crash tubes more. This paper aims to study crashworthiness performance of octagonal-inner double tubes under off-axis oblique impact load (0°, 10°, 20°, and 30°). The tubes have been connected with two walls, top wall as moving wall and a bottom wall as rigid wall underl different load angles. The tubes were made from Aluminum Alloy and consisted of a circular-outer tube and an octagonal-inner tube. The crashworthiness parameters of absorption of specific energy (SEA), maximum collapse force (Fmax) and efficiency of crush force (CFE) were obtained for all the structures. In order to get the value of parameters, the method of finite element analysis was used. The effects of different thickness of 1 mm, 2 mm, 3 mm and 4 mm and various oblique were studied. Based on numerical results, structures of 4 mm thickness were the greatest SEA of 26.39 kJ/kg among other thickness of structures. In addition, the value of energy absorption for tubes obliquely loaded decreased for all the size of thickness structures. Finally, this structure can be considered as crash box of vehicle in future

Influence of Connection Type and Platform Diameter on Titanium Dental Implants Fatigue: Non-Axial Loading Cyclic Test Analysis

Two-pieces dental implants must provide stability of the implant-abutment-interface. The connection type and platform diameter could influence the biomechanical resistance and stress distribution. This study aims to evaluate the fatigue for different types of connections, external and internal, and different platform diameters. Three implant designs with the same length were used: (a) external hexagon/narrow platform; (b) internal double hexagon/narrow platform; (c) internal octagon/regular platform. A fatigue test was developed to establish the number of cycles needed before fracture. A 30º oblique load with a sinusoidal function of fatigue at a frequency of 15 Hz and 10% stress variation was applied to each system. The fatigue load limit (FLL) for design (a) was 190 N, being the nominal-curvature-moment (NCM) = 1.045; FLL = 150 N, with a NCM = 0.825 for (b), and FLL = 325 N, with a NCM = 1.788 for (c). The platform diameter affects the FLL, obtaining lower FLL on a narrow platform. The connection type interferes with the implant walls’ width, especially in narrow implants, making internal connections more unstable at this level. Long-term clinical studies to assess the restoration’s success rate and survival are mandatory.

Model Researchon Oblique Load Carrying Capacity of Batter Pile Groups

Experimental investigations on model vertical and batter pile group in uniform sands are presented. Mild steel piles in two different medium ofsand are used in this investigation. The tests are conducted on model steel pile installed in medium, and dense sand withL/d ratio is 18.75 and different batter angles of 0°, 10°, 20°, and 30°. These piles are constructed in sand and subjected to uplift loads of 60° inclination. It was found that the uplift capacity of vertical and batter piles under inclined pulls increased with increase in inclination of piles.it is also observed it a negative batter pile has greater uplift load than positive batter pile