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Int Poster J Dent Oral Med 10 (2008), No. 2     15. June 2008

Int Poster J Dent Oral Med 2008, Vol 10 No 02, Poster 403

ESEM evaluation of three FRC post bonding systems

Language: English

Authors:
Dr. med. Thomas Klinke, Kathleen Zemmrich, Wolfgang Klimm
Poliklinik für Zahnerhaltung, Medizinische Fakultät Carl-Gustav-Carus, Technische Universität Dresden
Gerd Richter
Poliklink für Zahnärztliche Prothetik, Medizinische Fakultät Carl-Gustav-Carus, Technische Universität Dresden
Eva Haufe
Institut für Arbeits- und Sozialmedizin, Medizinische Fakultät Carl-Gustav-Carus, Technische Universität Dresden

Date/Event/Venue:
09-26-2007 - 09-29-2007
IADR Conference
Thessaloniki, Greece
 

Introduction

The use of endodontic fibre reinforced composite posts has increased in popularity because of their favourable physical and esthetic properties. The longevity of these posts is greatly influenced by the quality of adhesive bonding.

Objectives

The purpose of this study was to compare the interfaces formed by three different adhesive luting systems between endodontic posts and root canal dentine in vitro.
 

Material and Methods

A total of 120 extracted human incisors and canines were endodontically treated and their root canals were filled by lateral condensation of guttapercha. Post space preparation was performed with FRC Postec drills. The specimens were randomly divided into three groups of 40 samples each, and FRC Postec Plus posts (Ivoclar Vivadent, Schaan, Liechtenstein, Fig. 1) were inserted according to the manufacturer's instructions using three different bonding and luting systems.

Groups Adhesive system Self-etching Bonding steps Luting material
1 Excite no 1 Multicore flow
2 AdheSe yes 2 Multicore flow
3 Multilink Automix yes 1* Multilink Automix
Table 1: Adhesive luting systems (all Ivoclar Vivadent) used in the three sample groups
* Priming only; bonding step is integrated in the luting procedure
 

Between every handling the samples were stored in 0.9% saline solution containing 0.1% thymol. All specimens were longitudinally sectioned using a diamond saw at low speed and intense water coolant. The surface of interest was etched with 37% phosphoric acid for 15 seconds and examined with an environmental scanning electron microscope (ESEM; Philips, Eindhoven, Netherlands; Fig. 2) at 55 - 65% atmospheric humidity and a pressure of 670 - 800 kPa.

Fig. 1: FRC Postec Plus posts Fig. 2: ESEM workplace
 

The quality of the interfaces between post and dentine was evaluated within cervical, middle and apical segments of the root using a standardized protocoll (Table 2). The specimens exhibiting adhesive defects were in addition transversally sectioned into three segments. The cross-sectioned surfaces were microscopically examined in order to exclude artefacts caused by a loss of humidity during the first ESEM observation (Fig. 3+4).
Data were statistically analyzed by the application of the nonparametric Chi-square, Kruskal-Wallis and Friedman tests.

Fig. 3: ESEM Image of longitudinally sectioned sample Fig. 4: Longitudinally and cross-sectioned sample Fig. 5: ESEM Image of cross-sectioned sample
 
# 1 Interface between post ans luting composite
# 2 Interface between luting composite and adhesive
# 3 Interface between adhesive and dentine
a perfect interface
b partial adhesive defect
c complete adhesive defect
# 4 Hybrid layer
a complete hybrid layer
b incomplete or absent hybrid layer
Table 2: ESEM evaluation criteria for interfaces #1-4
 

Results

Interface #1: post - luting composite
All samples exhibited perfect interfaces between the post and the luting composite in each of the three segments of the root, except for one case.
 
Interface #2: luting composite - adhesive (Fig. 6)
A perfect interface between luting and adhesive materials was observed in most of the cases (Fig. 6a). There were no statistically significant differences between the materials. Regarding to the root segments, differences in the quality of interfaces were only found in group 1 (Excite / Multicore flow). Some partial and a few total adhesive defects were recognized. The fewest adhesive defects were in group 3 (Multilink Automix), while group 1 revealed complete defects in 10% of the apical root segments (Fig. 6b+c).

Figure 6a-c: Quality of interface #2 (luting composite - adhesive) at cervical, middle and apical levels of the root
 

Interface #3: adhesive - dentine (Fig. 7)
For this interface more distinct group-related differences became evident, proved to be significant in the middle and apical segment of the root (p<0.05). Group 1 showed the best, group 3 the worst results. Significant differences in the quality of interfaces between the three root segments were not observed.

Figure 7a-c: Quality of interface #3 (adhesive - dentine) at cervical, middle and apical levels of the root
 

Interface #4: Hybrid layer (Fig. 8)
The formation of a complete hybrid layer was closely related with a perfect interface between the adhesive and the dentine (Fig. 7a and 8). This correlation was significant for every group and root segment (p<0.05). In both the cervical and the middle third of the root, group 3 exhibited the highest number of incomplete or absent hybrid layers (p<0.05). Differences between the root segments were significant in group 2 only (p<0.001).
 
Combination of interfaces (Fig. 9+10)
The portion of samples, which proved to be perfect in each of the first three interfaces, is shown in Fig. 9, revealing a decreasing trend of interface quality from group 1 to 3 and from cervical to apical. Figure 10 displays the percentage of samples without any adhesive defects along the entire root, classified for material groups and interfaces. This graph also makes obvious the high correlation between the quality of interfaces #3 and #4 .

Fig. 8: Percentage of perfect hybrid layers Fig. 9: Percentage of perfect interfaces #1-3 Fig. 10: Percentage of perfect interfaces along the entire root
 
Fig. 11: ESEM Image of group 1 sample (Excite DC / Multicore flow) Fig. 12: ESEM Image of group 2 sample (AdheSE / Mulicore flow) Fig. 13: ESEM Image of group 3 sample (Multilink Automix)
 

Summary and Conclusions

One hundred and twenty FRC Postec Plus posts (Ivoclar Vivadent, Liechtenstein) were inserted in the roots of extracted human anterior teeth using three different adhesive luting systems of the same manufacturer. The interfaces between the post and the dentine were evaluated by ESEM examination of longitudinally sectioned specimens at cervical, middle and apical levels using morphological criteria.
Statistically significant differences between the different adhesive luting systems were found concerning the quality of the adhesive - dentine interface and the formation of a hybrid layer. Multicore flow combined with the adhesive Excite DSC, which is applied after conventional acid conditioning of the dentine, demonstrated better results than the self-etching two-step luting system Multilink Automix. The three-step self-etching system AdheSe DC / Multicore flow ranged between the other two groups.
In summary it can be stated that there were no serious differences between the luting systems used for FRC post insertion. However, the advantages of simplified luting procedures were accompanied by losses in bonding quality.
 

This Poster was submitted by Dr. med. Thomas Klinke.
 

Correspondence address:
Dr. med. Thomas Klinke
Technische Universität Dresden
Universitätsklinikum Carl Gustav Carus
Poliklinik für Zahnerhaltung
Fetscherstrasse 74
D-01309 Dresden
Germany