Degradation of a hybrid layer – review of literature

Introduction. The basic premise of adhesive dentistry
is to achieve the reliable chemical bond between
dental hard tissues and restorative composite
material. The hybrid layer is one of the key elements
of this interface. Unfortunately, over time the hybrid
layer wears out under the influence of physical and
chemical factors. As a consequence of this process,
marginal leakage forms along the restoration
interface, together with marginal discolorations,
and even the loss of filling retention. Two following
models of hybrid layer degradation were described:
disorganization of collagen fibres and hydrolysis
(loss) of the resin from the inter-fibrillar spaces
within the hybrid layer. Degradation of the collagen
matrix requires the coexistence of demineralization
and activation of endogenous enzymes present in the
dentine. Metalloproteinase of the dentine matrix can
be activated by caries or by the application of certain
types of bonding systems. Aim of the study. To review
up-to-date research results on factors affecting the
hybrid layer degradation. Conclusions. Both the type
of bonding system and the method of dentine surface
treatment have a significant impact on the quality
of the hybrid layer, and thus the durability of the
resulting adhesive bond. A proper clinical protocol
should be established in order to achieve the highest
bond strength between the composite material and the
dental hard tissue while minimizing degradation with
time.