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Azerbaycan Saytlari

 »  Home  »  Endodontic Articles 11  »  Micro-tensile bond strengths of bonding agents to pulpal floor dentine
Micro-tensile bond strengths of bonding agents to pulpal floor dentine
Results.



Pulpal floor dentine, after removal of the pulp prior to etching, showed irregular dome-shaped calcospherites of varying size with open dentinal tubules (Fig. 1).Tubule density averaged 24 500 tubulesmm_2. Only one accessory canal could be detected in the pulpal floor area of eight experimental teeth.
After etching with 34% phosphoric acid gel, the surface of pulpal floor dentine was demineralized and dentinal tubule orifices were enlarged. The surface irregularities of etched dentine were less apparent than in normal dentine and the dome-shaped calcospherites had mostly disappeared (Fig. 2).The acidic primer demineralized the dentine surface to a lesser degree, with the typical dome-shaped calcospherites remaining (Fig. 3).
The mean bond strength of the ‘one-bottle’ adhesive system (Prime & Bond NT) specimens was 15.58 _ 4.24 MPa and that of the self-etching-priming system (Clearfil SE Bond) specimens was 22.49 _7.08 MPa. Statistical analysis showed that the mean micro-tensile bond strength of Clearfil SE Bond specimens was significantly greater than that of Prime & Bond NT specimens (P < 0.05).
The failure mode (Table 3) for both the self-etching- priming and‘one-bottle’adhesive systems showed predominantly mixed failures of partial cohesive failure in dentine or partial cohesive failure in Bonding resin/composite (type 2). Of the mixed failure types, most Clearfil SE bond specimens revealed partial cohesive failure within dentine, whereas most Prime & Bond NT specimens showed partial cohesive failure in bonding resin composite.

Figure 1. SEM photograph of pulpal floor dentine showing an undulating surface of various sizes of dome-shaped calcospherites with open dentinal tubules (original magnification x500).

SEM photograph of pulpal floor dentine showing an undulating surface of various sizes of dome-shaped calcospherites with open dentinal tubules

Figure 2. SEM photograph of pulpal floor dentine after etching with 34% phosphoric acid gel (original magnification x500).

SEM photograph of pulpal floor dentine after etching with 34% phosphoric acid gel

Figure 3. SEM photograph of pulpal floor dentine after applying acidic primer and rinsing with acetone (original magnification x500).

SEM photograph of pulpal floor dentine after applying acidic primer and rinsing with acetone

Table 3. The four types of failure observed in fractured specimens by SEM.

The four types of failure observed in fractured specimens by SEM