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Polyetheretherketone (PEEK) has already been used for years in industry as well as medicine, whereas it is also gaining ground in the field of dentistry. In addition to the idea of metal-free and aesthetic dentures, the desire for long-term tooth preservation is increasing. A confrontation with a therapy of strongly destroyed teeth corresponding to the aesthetic requirements is thus indispensable whereby post constructions play a central role.
The study aimed at the examination of whether PEEK can be used as a root pin. Representative data of its adhesion with multi-step adhesives in the root canal compared to the adhesion numbers using titanium posts (Komet Dental) should have been collected.
Thus, 96 extracted teeth were decapitated and underwent a root canal treatment. After six months of storage, the root canals were reamed to the size of the posts which have then been placed and adhesively fixed in the root canal. The root pins consisting of titanium and PEEK (Komet Dental) were inserted using Panavia 21 (Kuraray), RelyX Ultimate (3M Espe), core-X flow (Dentsply Sirona) and Multilink Automix (Ivoclar Vivadent) resulting in eight test groups of twelve teeth each. After an additional storage period of one week, the pins were pulled out by using the material testing machine Zwicki 1120 (Zwick/Roell) which calculated the physical power needed providing information about the adhesion between the tooth and the post. In order to determine the localisation of the bond having dissolved during the pull-out-analysis, a fracture analysis was carried out which allowed a classification of cohesive, adhesive and combined failures.
The results have been statistically evaluated and tested on significance by means of an ANOVA. Significantly higher force values could be recorded using titanium pins in combination with all four fastening materials in contrast to root pins made of PEEK (p<.05). The shear strength of the titanium pins averaged 9.05 MPa, in case of PEEK 3.71 MPa whose bonding could be improved by sandblasting the pins’ surface and the use of the primer visio.link (Bredent).
The pull-out results also varied significantly in terms of the fastening materials within the titanium group (p<.001) with a greater statistical variance than PEEK.
Significant differences could be found between Panavia 21 and RelyX Ultimate (p=.001), Panavia 21 and core-X flow (p=.012) as well as between RelyX Ultimate and Multilink Automix (p=.017). Panavia 21 achieved the highest average bond strength in both, the titanium (11.93 MPa) and the PEEK groups (3.71 MPa). RelyX Ultimate showed the lowest shear strength on average in both cases (titanium: 6.25 MPa; PEEK: 3.19 MPa).
Within the titanium group, the fractional analysis revealed solely, in case of PEEK pre-dominantly mixed failures. With a significance of p=.007, there were significant differ-ences between the root pin materials regarding the fracture mode. For PEEK, in most cases the bond between the post and the fastening material turned out to be the strong-est in the particular compound system.