Comparison of load-bearing capacity of direct resin-bonded fiber-reinforced composite FPDs with four framework designs

Xie, Qiufei; Lassila, Lippo V.J.; Vallittu, Pekka K.

doi:10.1016/j.jdent.2007.04.003

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Volume 35, Issue 7 , Pages 578-582, July 2007

Comparison of load-bearing capacity of direct resin-bonded fiber-reinforced composite FPDs with four framework designs

Qiufei Xie
- Department of Prosthodontics, School and Hospital of Stomatology, Peking University, Beijing, China
- Department of Prosthetic Dentistry and Biomaterials Science, Institute of Dentistry, Faculty of Medicine, University of Turku, Turku, Finland
- Corresponding author at: Department of Prosthodontics, School and Hospital of Stomatology, Peking University, Zhongguancun Southern Avenue 22 Haidian District, 100081 Beijing, China. Tel.: +86 10 62179977x2552; fax: +86 10 62173402.
Lippo V.J. Lassila
- Department of Prosthetic Dentistry and Biomaterials Science, Institute of Dentistry, Faculty of Medicine, University of Turku, Turku, Finland
Pekka K. Vallittu
- Department of Prosthetic Dentistry and Biomaterials Science, Institute of Dentistry, Faculty of Medicine, University of Turku, Turku, Finland

Received 14 September 2006; received in revised form 27 March 2007; accepted 2 April 2007.

Abstract

Objectives

This in vitro study was aimed to compare the fracture resistance of directly fabricated inlay-retained fiber-reinforced composite (FRC) fixed partial dentures (FPDs) with four types of framework designs.

Methods

Forty-eight directly fabricated inlay retained FPDs were made of FRC and particulate resin composite (everStick/Tetric flow and Ceram). Extracted human mandibular first premolars and first molars were as abutments. The following framework designs were tested: in the Group A (control group), the framework was made of two prepregs of unidirectional glass FRC; the Group B, two prepregs in pontic portion were covered with one layer of multidirectional fiber veil FRC; the Group C, the FRC prepregs were covered in pontic portion with four short unidirectional FRC pieces along the main prepregs; in Group D, one short unidirectional FRC prepregs were placed on the main prepregs in 90° angle to the main framework. After thermal cycling, FPDs of each group (n=12) were randomly divided into two subgroups (n=6). Fracture test was performed at the universal testing machine (1mm/min) where FPDs were loaded from the occlusal direction to the occlusal fossa or to the buccal cusp. Failure patterns were observed with stereomicroscope. Median and 25%/75% percentile values were calculated and nonparametric analysis was performed.

Results

Compared with three other framework designs, the FPDs in Group D showed the highest resistance when loading to the occlusal fossa, with maximum load of 2353.8N (25%/75%: 2155.5/2500.0) (p=0.000, 0.000, and 0.005 for compared with Group A, B, and C). The same group showed also higher resistance when loaded to the buccal cusp (1416.3N (1409.2/1480.8)) if compared to the FPDs of the Group A and Group C (p=0.044, 0.010). In general the FPDs showed higher resistant to loading at the occlusal fossa (p<0.05).

Conclusions

This in vitro study showed that inlay-retained FRC FPD constructed with direct technique provided high fracture resistance. The framework design that provided support for the veneering composite of the pontic contributed to the highest load-bearing capacity even when loaded to the buccal cusp.

Keywords: Fiber-reinforced composite, Fixed partial dentures, Fracture strength, Framework design