Einfluss des Zahnalters auf den Haftverbund intrakanalär befestigter Wurzelstifte unter Verwendung der Befestigungskomposite SpeedCEM Plus und Multilink Automix

The restoration of endodontically treated teeth with large coronal loss generally requires the insertion of an intraradicular post to provide adequate retention for the final restoration. While the properties of the post material and the luting cement have been determined by the manufacturer and their bond has already been adequately investigated, the bond between the luting cement and the root canal wall is dependent on the properties of the root dentine. However, these are by no means to be regarded as constant, since a change in the structure and physical properties occurs in the course of physiological aging. The present study investigated the influence of tooth age on the adhesion of two different luting systems for the adhesive luting of root canal posts. For this purpose, adhesion values were measured on specimens of different ages using the pull-out-method. From a number of endodontically untreated, extracted human teeth with straight root canals and a preferably round anatomy of canal cross-sections, 60 suitable test teeth were selected. A radiographic examination of the root canal anatomy was performed. The test teeth were divided into three age groups (young: 20 - 35 years, middle-aged: 45 - 60 years, old: 70 - 85 years). Ten teeth of each age group were then randomly assigned to one of the two luting systems (SpeedCEM Plus, Multilink Automix), resulting in six test groups. In order to prevent dehydration, the test teeth were continuously stored moist in sodium acylide solution. In order to achieve the same bonding surface in each case, the teeth were decoronated and the root canals were mechanically prepared up to size ISO 60 with a root canal length of 8 mm. The preparation steps were accompanied by intermediate rinses with distilled water. Subsequently, the cementation of conditioned steel spreaders ISO 60 prepared for the purpose of the study was carried out using SpeedCEM Plus (Ivoclar Vivadent) and Multilink Automix (Ivoclar Vivadent). After a 14-day curing period, the bond strength analysis was performed using the pullout- method in a universal testing machine. In addition, the fracture mode was determined by photos. The median bond strength values in the three age groups for the investigated luting composites ranged from 6.48 to 7.95 MPa for SpeedCEM Plus and from 7.64 to 8.71 MPa for Multilink Automix. When the three age groups were compared using ANOVA, no significant differences were found (SpeedCEM Plus p = 0.225 and Multilink Automix p = 0.938). In a pairwise comparison of all combination possibilities of the age groups, no significant differences with regard to tooth age could be found. For SpeedCEM Plus, the significance values for young vs. middle-aged were p = 0.997, for young vs. old p = 0.972 and for middle-aged vs. old p = 0.877. For Multilink Automix, the significance values for young vs. middle-aged were p = 0.240, for young vs. old p = 0.386 and for middle-aged vs. old p = 0.826. The median of the bond strength values of both luting composites were compared pairwise using t-test for all three age groups. No significant differences were found between the two luting composites in any age group. Significance values for the young age group were p = 0.284, for the medium age group p = 0.876 and for the old age group p = 0.806. Regarding the fracture modes, mixed fracture occurred in 41 cases, adhesive failure to dentin in eight cases, cohesive failure in cement in seven cases, and adhesive failure to the spreader in only four cases. With a total share of 68%, mixed fracture was the dominant fracture mode. A significant correlation between fracture mode and bond strength could not be found with p = 0.423. Based on the analyses, no age-dependent differences in terms of bond strength could be determined for the two luting composites Multilink Automix and SpeedCEM Plus. Thus, both composites are equally suitable for the adhesive cementation of root posts for all three age groups (young, middle-aged, old). There were also no significant differences in the adhesive bond between the two composites. Thus, both are equally well suited for adhesive cementation.