Implant-supported crowns remain an ideal treatment option for the replacement of a missing tooth. The provisionalization phase remains a critical step between surgery and final crown placement, guiding soft tissue healing and providing esthetics and function. Although there are several possible pathways for provisionalization, the options are time-consuming, technically difficult and expensive, resulting in confusion and frustration for the dentist and cost and time for the patient. A novel dental implant abutment has been developed that aims to resolve the shortcomings of current abutments and the provisionalization process. 3D printing or additive manufacturing, with plastic and metal, were employed as an alternative approach for production of the prototype abutment. Scanning, computer-aided design and 3D plastic and metal printing were employed. Abutments were fabricated in MED690 VeroDentPlus and Duraform 316L stainless steel, respectively. Prototypes were printed with a claimed accuracy of 16 µm (plastic) and 8 µm (metal). The prototypes were qualitatively assessed for functionality by implant threading and simulated provisionalization process in a laboratory setting. The plastic prototypes were not suitable due to threading issues and material weakness. Metal prototypes tolerated artificial tooth fabrication successfully but concerns with thread pitch and accuracy remained. 3D metal printing appears to be a suitable alternative to traditionally machined implant components; however, post-production processing seems to be required. Further research is warranted.

The aim of this study was to assess and compare the stress–strain pattern of zygomatic dental implants supporting different superstructures using 3D finite element analysis (FEA). A model of a tridimensional edentulous maxilla with four dental implants was designed using the computer-aided design (CAD) software. Two standard and two zygomatic implants were positioned to support the U-shaped bar superstructure. In the computer-aided engineering (CAE) software, different materials have been simulated for the superstructure: cobalt–chrome (CoCr) alloy, titanium alloy (Ti), zirconia (Zr), carbon-fiber polymers (CF) and polyetheretherketone (PEEK). An axial load of 500 N was applied in the posterior regions near the zygomatic implants. Considering the mechanical response of the bone tissue, all superstructure materials resulted in homogeneous strain and thus could reconstruct the edentulous maxilla. However, with the aim to reduce the stress in the zygomatic implants and prosthetic screws, stiffer materials, such Zr, CoCr and Ti, appeared to be a preferable option.

The purpose of this in silico study was to investigate the effect of abutment screw torque and implant-abutment contact surfaces on the stress generation, microgap formation and simulated fatigue life of an external hexagon connection under oblique loading. Three-dimensional numerical models of the external hexagon implant were modeled containing two different implant-abutment contact surfaces (with and without contacting the hexagon axial walls) as well as using screw torques of 20 Ncm or 30 Ncm. Following the ISO 14801, an oblique load of 100 N was applied to the prosthesis. The von Mises stress, microgap formation, safety factor and fatigue life were obtained. The stresses in the abutment screw and implant were minimally influenced by the screw torque. However, this minimal stress in the screw with a 30 Ncm torque reduced the calculated fatigue life in comparison with 20 Ncm when the external hexagon axial walls were not in contact at the implant-abutment interface. The safety factor for the implant was higher when using minimal surfaces at the abutment-interfaces; however, it compromised the screw safety factor increasing its failure probability. The higher the screw torque, the lower was the microgap formation at the implant-abutment interface. However, the calculated residual stress is proportional to the applied torque, reducing the fatigue life in the screw. This effect can be attenuated using an implant-abutment system with more contacting surfaces.

Background: Orofacial injuries are common occurrences during contact sports activities. However, there is an absence of data regarding the performance of hybrid occlusal splint mouthguards (HMG), especially during compressive loading. This study amid to evaluate the biomechanical effects of wearing a conventional custom mouthguard (MG) or the HMG on the teeth, bone, and the device itself. Methods: To evaluate the total deformation and stress concentration, a skull model was selected and duplicated to receive two different designs of mouthguard device: one model received a MG with 4-mm thickness and the other received a novel HMG with the same thickness. Both models were subdivided into finite elements. The frictionless contacts were used, and a nonlinear analysis was performed simulating the compressive loading in occlusion. Results: The results were presented in von-Mises stress maps (MPa) and total deformation (mm). A higher stress concentration in teeth was observed for the model with the conventional MG, while the HMG design displayed a promising mechanical response with lower stress magnitude. The HMG design displayed a higher magnitude of stress on its occlusal portion (7.05 MPa) than the MG design (6.19 MPa). Conclusion: The hybrid mouthguard (HMG) reduced (1) jaw displacement during chewing and (2) the generated stresses in maxillary and mandibular teeth.

Mouthguards (MG) are protective devices that can reduce the risks of facial trauma. However, many athletes do not use them. Additionally, MG wear with coincidental parafunctional activity has not been considered. The aim of this study was to evaluate the stress distribution as a consequence of a direct impact comparing a conventional MG with a novel hybrid appliance (HMG). Using computer-aided design (CAD) software, a human skull was modeled with the teeth inserted into their respective alveolus. The models were divided according to the MG type (conventional or hybrid). The geometries were exported to the computer-aided engineering (CAE) software and the materials were considered isotropic. Fixation was defined at the base of the maxilla. The load was applied using a hockey puck. The total deformation (mm) and the von Mises stress (MPa) results were obtained for the MGs (conventional and hybrid), upper teeth, lower teeth, and maxillary bone. Despite the presence of an MG, it is still possible to observe generated stress in all structures. However, the hybrid design was more efficient than the conventional design in reducing the displacement during the impact and consequently the stress on the upper teeth, lower teeth, and maxillary bone. Higher stress magnitude was more concentrated at the inner portion of the hybrid design than the conventional device. The HMG appliance decreased the stress concentration in the teeth and in the bone, limiting the areas susceptible to injuries to the regions directly impacted by the hockey puck. Although the novel HMG may mitigate injury, some stress will still result, and any possible injury should be evaluated by a dental professional.

The esthetic rehabilitation of a patient is a demanding yet rewarding procedure, improving the form, function, and well-being of a patient. Three-dimensional (3D) printed, or additive manufactured, zirconia has recently entered the dental space, but without a thorough assessment or comparison. This pilot study utilized digital impressions of two demonstration casts: Cast 1 prepared both central incisors for full ceramic crown coverage, while cast 2 had a lateral incisor (#22) prepared for a ceramic veneer. Both casts underwent digital scanning (Straumann CARES 3, Straumann, Basel, Switzerland) to create virtual STL models. Cast 1 had two full zirconia anterior crowns digitally designed, and Cast 2 had a zirconia veneer digitally designed, using Exocad GmbH software by a certified dental technician at Schulich Dentistry. The STL files were used for fabricating six milled zirconia crowns for central incisor (#21) and six 3D-printed zirconia crowns for the other central incisor (#11). Similarly, for Cast 2, milled and 3D-printed zirconia veneers were made for the prepared lateral incisor (#22). Statistical analysis employed Minitab 16.1.0 software to construct a 2 × 2 table for cross-tabulation and chi-squared analysis. This statistical approach assessed the relationship between restoration design and processing method. Cochran–Mantel–Haenszel test evaluated categorical variables considering different classification variables. Milled restorations showed minor variations, while 3D-printed units displayed consistency. Statistical tests found no significant associations. This in vitro study suggests 3D-printed zirconia for crowns and veneers meets precementation standards akin to conventionally milled restorations. Further research can assess its potential benefits for dentistry's efficiency, cost, and sustainability.