Biodentine

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(O’Brien 2008)). This maturation process can be related to the decrease of porosity with
time, which was illustrated previously. Biodentine is an evolutive biomaterial which
improves its mechanical properties with time.
Comparing the compressive strength of a classical glass ionomer (Fuji IX – GC), at 1 hour,
the compressive strengths are similar. No continuous increase over one month can be
observed with Fuji IX but Biodentine is significantly more resistant to compression.
With ProRoot ® MTA, even after 1 day, the material has no mechanical resistance. As
classical Portland cement, the mechanical strength develops after several days, reaching
150 MPa after one week.
This demonstrates the superiority of Biodentine for building in short time (9-12 min)
sufficient mechanical resistance to be used as a dentine substitute, compatible with
dental restorations.
2.4 - Flexural strength
The 3 points bending test has a clinical significance and is essential when the material
is used for Class I, II and IV cavities. The higher the resistance to flexural strength, the
lower the risk of fracture in clinical use.
The value of the bending obtained with Biodentine after 2 hours is 34 MPa. Compared
with that of other materials: 5-25 MPa (conventional Glass Ionomer Cement), 17-54 MPa
(Resin modified GIC), 61-182 MPa (composite resin) (O’Brien 2008), it shows clearly that
the bending resistance of Biodentine is superior to conventional GIC, but still much
lower than the composite resin.
The internal values of the flexural strength were 22MPa, very similar to Glass Ionomers
(15-39MPa).
2.5 - Vickers micro hardness
Hardness can be defined as the resistance to the plastic deformation of the surface of
a material after indentation or penetration. Measurements at different times have been
evaluated
The hardness increases in time when cements are immersed in distilled water (Colon in
(Golberg et al., 2009)). After 2 hours, the hardness of Biodentine was 51 HVN and
reached 69 HVN after 1 month. These values are comparable to those obtained with
the resin modified GIC-Fuji II LC (36 HVN), and the composite resin-Post Comp II LC
(97 HVN). Calcite is a mineral known to improve the hardness of cements. The formation
of CSH gel reduces the porosity with time. The crystallization of the latter continues,
therefore improving the hardness as well as other mechanical properties (sealing at the
interfaces, compressive strength…).
The reported micro hardness values for natural dentine are in the range of 60-90 HVN
(O’Brien 2008). Biodentine has surface hardness in the same range as natural dentine.