Porcelain sectional veneers, an ultra-conservative technique for diastema closure (three-dimensional finite element stress analysis)

Abstract

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.

Ceramic partial laminate veneers in anterior teeth: A literature review

“…Higher stress concentrations in the ceramic were observed for thicker resin cement layers, which increased the risk of failure when the ceramic was subjected to higher temperatures [28]. A similar finite element analysis by the same authors [29] showed an increased stress concentration when forces were applied directly to the ceramic, particularly at higher inclination angles (137°)…”

Midline diastema closure using a lithium disilicate glass ceramic fragment: increased long-term color stability”.

“…Finally, occlusion must also be carefully considered, since high stress could be distributed at direct oclusal and inclined forces (15) , thus, direct contact to the interface must be avoided to ensure the integrity of the restoration…”

Minimally Invasive Diastema Restoration with Prefabricated Sectional Veneers

“…In clinical studies, ceramic veneers show excellent clinical performance [51][52][53] and, in a recent systematic review and meta-analysis, the estimated overall cumulative survival rate of glass-ceramic and feldspathic porcelain veneers was 89% in a median follow-up period of 9 years [54]. However, at the moment, there is no clinical study reporting on the longevity of ceramic sectional veneers and it is possible that their survival rate would not be as good as conventional ceramic veneers because laboratory studies show high stress concentrations at the bonding interface of ceramic sectional veneers [55]. In a three-dimensional finite element analysis, ceramic sectional veneer diastema restoration shows a significantly higher stress concentration than direct composite diastema restoration and the larger the size of the diastema, the higher the von Mises stress value.…”