J Korean Acad Conserv Dent.  2010 Jul;35(4):257-266. 10.5395/JKACD.2010.35.4.257.

Influence of post types and sizes on fracture resistance in the immature tooth model

• Kim JH
• Park SH
• Park JW
• Jung IY

• KMID: 2176381
• DOI: http://doi.org/10.5395/JKACD.2010.35.4.257

Abstract

The purpose of this study was to determine the effect of post types and sizes on fracture resistance in immature tooth model with various restorative techniques. Bovine incisors were sectioned 8 mm above and 12 mm below the cementoenamel junction to simulate immature tooth model. To compare various post-and-core restorations, canals were restored with gutta-percha and resin core, or reinforced dentin wall with dual-cured resin composite, followed by placement of D.T. LIGHT-POST, ParaPost XT, and various sizes of EverStick Post individually. All of specimens were stored in the distilled water for 72 hours and underwent 6,000 thermal cycles. After simulation of periodontal ligament structure with polyether impression material, compressive load was applied at 45 degrees to the long axis of the specimen until fracture was occurred. Experimental groups reinforced with post and composite resin were shown significantly higher fracture strength than gutta-percha group without post placement (p < 0.05). Most specimens fractured limited to cervical third of roots. Post types did not influence on fracture resistance and fracture level significantly when cement space was filled with dual-cured resin composite. In addition, no statistically significant differences were seen between customized and standardized glass fiber posts, which cement spaces were filled with resin cement or composite resin individually. Therefore, root reinforcement procedures as above in immature teeth improved fracture resistance regardless of post types and sizes.

Keyword

Immature tooth; Fracture resistance; Fiber post; Titanium post; EverStick(R) Post; Post size

MeSH Terms

Axis, Cervical Vertebra
Composite Resins
Dentin
Glass
Gutta-Percha
Incisor
Periodontal Ligament
Reinforcement (Psychology)
Resin Cements
Tooth
Tooth Cervix
Water
Composite Resins
Gutta-Percha
Resin Cements
Water

Figure

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  Figure 1 Model of immature permanent incisor. Sectioned part of bovine tooth; the crown had a length of 8 mm from the cementoenamel junction, the root was 12 mm in length from the cementoenamel junction.

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  Figure 2 The width of remaining root dentin and the size of the specimen is measured with the electronic digital caliper.

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  Figure 3 Schematic diagrams of intracanal and coronal restorations.

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  Figure 4 0.2 mm-thick sheet wax is pressure welded on the root surface. The specimen is placed in the acetal mold, and autopolymerizing acrylic resin is injected into the mold.

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  Figure 5 Device is positioned for the compressive load application at 45° to the long axis of tooth specimen. Compressive load is applied to the lingual incisal edge of the specimen.

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  Figure 6 Box plots of fracture load (median, 25th and 75th percentiles) of the control and experimental groups (N).

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  Figure 7 The ratio of restorable and non-restorable fractures in the control and experimental groups.

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  Figure 8 Location of fracture line (a) Restorable fractures (b) Non-restorable fractures

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