Abstract
Objective The aim of this study was to evaluate the efficiency of slab shear bond strength
test (Slab_SBS) versus the microtensile in evaluation of the bond strength of different
substrates.
Materials and Methods Forty-eight extracted caries-free human third molars were utilized for teeth specimens'
preparation. After flattening of all molars' occlusal table, the specimens were divided
into two groups based on the type of utilized restorative material: nanohybrid resin
composite and resin-modified glass ionomer (RMGI). Each group was further subdivided
into three subgroups according to the subsequently applied bond strength test and
specimen width; microtensile bond strength test (μTBS), Slab_SBS [2 mm] and Slab_SBS
[3 mm]. Both testing methods were additionally applied on CAD/CAM specimens, nanohybrid
resin composite blocks (composite-to-composite), and ceramic blocks (ceramic-to-ceramic).
CAD/CAM specimens were prepared and cemented and then sectioned and subdivided as
followed for teeth specimens' preparation. Pretest failures (PTF), bond strength,
and failure mode of each specimen were recorded. Representative three-dimensional
(3D) finite element analysis (FEA) models were developed to simulate μTBS and Slab_SBS
specimens. Data were statistically analyzed using Shapiro–Wilk test and Weibull analysis.
Results Pretest failures were only noted in the μTBS subgroups. Slab_SBS provided comparable
bond strength to the μTBS of all substrates with adhesive mode of failure.
Conclusion Slab_SBS is easier to prepare with consistent and predictable outcome with no pretest
failures during specimen preparation and better stress distribution.
Keywords
slab shear - microtensile - pretest failure - bond strength test - failure mode -
finite element analysis
