ABSTRACT

Objective: This study assessed fracture resistance of two different extensions (2-mm, 4-mm) endocrowns and post crown of maxillary premolar using Vita Enamic. Finite element analysis (FEA) was utilized to analyze biomechanical behavior.

Methods & Materials: Thirty sound maxillary premolars were collected, decapitated 2-mm supra cementoenamel junction (CEJ) then fixed into epoxy resin 2-mm below CEJ. Fixed premolars were endodontically treated and splitted into three groups depending on preparation into 2-mm, 4-mm extensions endocrowns and post crown. Vita Enamic was the construction material. After cementation, specimens were further sub-grouped according whether to be thermocycled or not then all specimens were loaded vertically till failure. Data statistically analyzed. 3D finite models were designed as simulation of endontically treated maxillary premolar restored with 2-mm and 4-mm extensions depth endocrowns. Vertical and 45⁰ oblique loads of 300N were analyzed.

Results: showed that fracture resistance was the highest in 4-mm depth endocrown (1862.30 ± 51.9) followed by 2-mm endocrown (1536.95 ± 44.2). Post crown recorded the lowest (1142.97 ± 64.3). There was no statistical difference between thermocycled and non thermocycled except for post crown since thermocycled ones recorded lower results (907.12 ± 42.7). In finite element analysis 4-mm endocrown produced less stress than 2-mm with stresses diffusion toward cervical palatal area.

Conclusion: it was concluded that endocrown is a promising alternative to post crown in maxillary premolar. Fracture resistance influenced by extension depth while thermocycling mainly affected full coverage. FEA is a useful tool to predict failure mode.