Stress Pattern Variations in Operatively Prepared Human Teeth, Studied by Three-Dimensional Photoelasticity

Johnson, Earl; Castaldi, Cosmo R.; Gau, Dominik; Wysocki, George P.

doi:10.1177/00220345680470040601

Cited by 37 publications

(16 citation statements)

References 4 publications

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“…[21] The internal form of an intra-coronal preparation may affect the susceptibility of the tooth to fracture at least in theory, because sharp angles tend to concentrate stresses. [22, 23] If laser ablation is to be used for preparing intra-coronal cavity preparations, the quality of the surface could affect the subsequent susceptibility of the restored tooth to fracture. Even if the internal form of the resulting preparation is rounded, small surface cracks can still serve as initiation sites for eventual catastrophic failure.…”

Section: Discussionmentioning

confidence: 99%

Weakening of dentin from cracks resulting from laser irradiation

Staninec

Meshkin

Manesh³

et al. 2009

Dental Materials

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Cracking of tooth structure is a frequent mechanism of clinical failure necessitating treatment. Some laser conditions, particularly those without sufficient water cooling, may cause surface cracking of dentin. Surface cracks may serve as initiation sites for the onset of catastrophic fracture under mechanical stress, resulting in failure of the dentin. In this study, the hypothesis that laser initiated cracks result in lower bending strength of dentin was tested. Dentin beam specimens were prepared from human molar teeth, 1.1 × 1.1 × ~9 mm, and divided into groups C (control), W (wet), D (dry) of 12 beams each. In groups W, D, the middle of each beam on one surface (buccal) was irradiated with either a Er-YAG or Q-switched Er-YSGG laser and measured under a microscope, noting the dimensions in the irradiated area and immediately adjacent to irradiated area. Each beam was placed in a mechanical testing machine in a four-point bend jig and tested each with a monotonically increasing load at a displacement rate of 1 mm/min until failure. The bending strengths for groups C, W (Er-YAG laser) and D (Q-switched Er-YSGG laser) were, respectively, 141.6, 114.0, and 90.9 MPa. A one-way ANOVA determined a significant difference between groups C and D, p<0.001. Conclusion The Q-switched Er-YSGG laser without water caused cracks in the surface that significantly decreased the bending strength of dentin.

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Section: Discussionmentioning

confidence: 99%

Weakening of dentin from cracks resulting from laser irradiation

Staninec

Meshkin

Manesh³

et al. 2009

Dental Materials

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“…Finite-element 18,19) or photoelasticity 20) analyses are conventional evaluation techniques used to assess the polymerization shrinkage patterns shown by resins. They are in silico modeling studies that use the theoretical characteristics of each composite; therefore, they do not explore the shrinkage behavior of in vivo cavities.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional X-ray micro-computed tomography analysis of polymerization shrinkage vectors in flowable composite

et al. 2014

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The polymerization shrinkage of flowable resin composites was evaluated using air bubbles as traceable markers. Three different surface treatments i.e. an adhesive silane coupling agent, a separating silane coupling agent, and a combination of both, were applied to standard cavities. Before and after polymerization, X-ray micro-computed tomography images were recorded. Their superimposition and comparison allowed position changes of the markers to be visualized as vectors. The movement of the markers in the resin composite was, therefore, quantitatively evaluated from the tomographic images. Adhesion was found to significantly influence shrinkage patterns. The method used here could be employed to visualize shrinkage vectors and shrinkage volume.

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“…Photoelasticity has been used in a wide number of dental biomechanical studies [29]. It has been applied in 2-D and 3-D studies of cavity preparation and dental restorations, to perform stress analysis [30][31][32][33], and it was also applied in the study of endodontic posts [33,34]. Standlee et al [34] have performed a comparative analysis of three types of posts regarding design, insertion, length, and ability to transmit forces to supporting structures.…”

Section: Dental Applicationsmentioning

confidence: 99%