Background. Long span is seen in many clinical situations. Treatmentplanning options of these cases are difficult and may require FPD, RPD or ISP. Each option has its own disadvantages, including mechanical problems, patient comfort and cost. This article will evaluate the stress distribution of a different treatment option, which consists of adding a single sup-porting implant to the FPD by using 3D finite element analysis.Methods. Three models, each consisting of 5 units, were created as follows: 1. Tooth Pontic Pontic Pontic Tooth; 2. Tooth Pontic Implant Pontic Tooth; 3. Tooth Pontic Pontic Implant Tooth. An axial force was applied to the prostheses by using 3D finite element method and stresses were evaluated.Results. The maximum stress was found in the prostheses in all the models; the highest stress values in all the shared components of the models were almost similar. Stress in implants was lower in the second model than the third one.Conclusion. Adding a supporting implant in long-span FPD has no advantages while it has the disadvantages of complicating treatment and the complications that may occur to the implant and surrounding bone.

Background. Porcelain sectional veneers with no preparation (no-prep) are an ultra-conservative choice for the esthetic treatment of the anterior teeth. They can be made from a sintered feldspathic porcelain, which gives a great appearance with small thickness, but there are still concerns about the fracture strength of this material. Objectives. The aim of this study was to evaluate the fracture strength of porcelain sectional veneers made from 2 different sintered feldspathic porcelains. Material and methods. Twenty recently extracted human incisors were randomly divided into 2 groups according to the porcelain material (n = 10). The 1 st group was applied the IPS Style ® Ceram feldspathic porcelain and the 2 nd group-GC Initial TM MC. The porcelain sectional veneers were fabricated following the manufacturers' instructions. After the veneers bonded with resin cement (Variolink ® N), the fracture strength was measured using a universal testing machine (Instron ® 1195) at 1 mm/min until failure occurred. Failure modes were determined under a stereomicroscope. Results. The mean fracture strength for group IPS Style Ceram was higher than that for group GC Initial MC (182.7 N and 155.7 N, respectively). The lowest value was observed in group IPS Style Ceram (78 N) and the highest value-also in the group IPS Style Ceram (294 N). Student's t-test demonstrated no statistically significant differences between the 2 groups (p > 0.05). Conclusions. There was no difference in the fracture strength of the porcelain sectional veneers for the 2 types of sintered porcelain used in this study. Cohesive failure within the porcelain sectional veneer was the most common mode of failure.

Background. Diastema can be closed using conservative and non-conservative techniques. Composite resin wings and ceramic veneers are the most common treatment options if there is no indication for orthodontic treatment. A novel ultra-conservative technique has been introduced to the practice, i.e., porcelain sectional veneers can be fabricated with no or minimum preparation. However, porcelain is known for its poor mechanical properties and the long-term survival of such restorations is questionable. Objectives. This paper aimed to investigate the mechanical aspects of porcelain sectional veneers by means of the finite element method (FEM). Material and methods. A three-dimensional (3D) model of porcelain sectional veneers on the upper central incisors with diastema was obtained by the reversed engineering method starting from a cone-beam computed tomography (CBCT) image. A 100 N occlusal force was applied parallel and 135° to the longitudinal axis, respectively. For each direction the force was applied once with direct contact and again with no contact with the porcelain sectional veneers. For each of the resulting 4 scenarios, a 3D finite element analysis was simulated and the maximum equivalent von Mises stress was compared to porcelain flexural strength. Results. Higher stresses were detected when the force was applied on the porcelain sectional veneers and they were increased dramatically with the inclined force. Conclusions. Direct occlusal contact has to be avoided when using porcelain sectional veneers and the margin positions must be chosen carefully. The occlusal scheme must be noted carefully before choosing this type of restoration.

Context and Aims:Long span is seen in many clinical situations; treatment planning options of these cases are difficult and may require: Fixed partial denture (FPD), removable partial denture, or implant supported prostheses. Each option has its own disadvantages: Mechanical, patient relief, and cost, respectively. This article will evaluate the stress distribution of another treatment option, which is adding a single supporting implant to the FPD using three-dimensional (3D) finite element analysis.Subjects and Methods:Three models, each consisting of 5 units, were created as following: (1) Tooth pontic pontic pontic tooth, (2) tooth pontic implant pontic tooth, (3) tooth pontic pontic implant tooth. An axial force was applied to the prostheses using 3D finite element method, and stress was evaluated.Results:Maximum stress was found in the prostheses in all models, highest stress values in all shared components of the models were close. Stress in implants was less in the second model than the third one.Conclusions:Adding a supporting implant in long span FPD has no advantages, whereas it has the disadvantages of complicating treatment and the complications that may occur to the implant and surrounding bone itself.