Effects of Rehydration on Dentin Strengthened by Heating or UV Irradiation

Abstract

Type I collagen, the major organic component of human dentin, plays an important role in regulating the mechanical strength of dentin. Collagen in dentin can be strengthened by heating. We hypothesized that UV irradiation could produce similar strengthening effects and might maintain the strength of dentin after rehydration. Beam-shaped dentin specimens from the crowns of human third molars were subjected to flexural testing. Flexural strengths were two and three times greater than those in the control group after 5 minutes’ UV irradiation and heating to 140°C, respectively. After 30 days of rehydration, the heated specimens reverted to their original strength, whereas the UV specimens were 69% stronger than the original. Raman spectra of dental collagen were unchanged after heating, whereas several peaks, including a C-C bond in a proline ring, were amplified by UV irradiation. It is concluded that dentin strengthened by UV irradiation retains strength after rehydration because of chemical changes in collagen.

Get full access to this article

View all access options for this article.

References

Banse X, Sims TJ, Bailey AJ -2002-. Mechanical properties of adult vertebral cancellous bone: correlation with collagen intermolecular cross-links. J Bone Miner Res17:1621–1628.

Bedran-Russo AK, Pashley DH, Agee K, Drummond JL, Miescke KJ -2008-. Changes in stiffness of demineralized dentin following application of collagen crosslinkers. J Biomed Mater Res B: Appl Biomater86:330–334.

Burnett GW, Zenewitz J -1958-. Studies of the composition of teeth. VII: The moisture content of calcified tooth tissues. J Dent Res37:581–589.

Cooper DR, Davidson RJ -1965-. The effect of ultraviolet irradiation on soluble collagen. Biochem J97:139–147.

Cooper DR, Davidson RJ -1966-. The effect of ultraviolet irradiation on collagen-fold formation. Biochem J98:655–661.

Frushour BG, Koenig JL -1975-. Raman scattering of collagen, gelatin, and elastin. Biopolymers14:379–391.

Hayashi M, Koychev EV, Okamura K, Sugeta A, Hongo C, Okuyma K, et al. -2008-. Heat treatment strengthens human dentin. J Dent Res87:762–766.

Inoue S, Pereira PNR, Kawamoto C, Nakajima M, Koshiro K, Tagami J, et al. -2003-. Effect of depth and tubule direction on ultimate tensile strength of human coronal dentin. Dent Mater J22:39–47.

Jameson MW, Hood JA, Tidmarsh BG -1993-. The effect of dehydration and rehydration on some mechanical properties of human dentin. J Biomech26:1055–1065.

10.

Jorge-Herrero E, Fernández P, Turnay J, Olmo N, Calero P, Garcia R, et al. -1999-. Influence of different chemical cross-linking treatments on the properties of bovine pericardium and collagen. Biomaterials20:539–545.

11.

Lieber CA, Mahadevan-Jansen A -2003-. Automated method for subtraction of fluorescence from biological Raman spectra. App Spectrosc57:1363–1367.

12.

Miguez PA, Pereira PN, Atsawasuwan P, Yamauchi M -2004-. Collagen cross-linking and ultimate tensile strength in dentin. J Dent Res83:807–810.

13.

Nalla RK, Balooch M, Ager JW III, Kruzic JJ, Kinney JH, Ritchie RO -2005-. Effects of polar solvents on the fracture resistance of dentin: role of water hydration. Acta Biomater1:31–43.

14.

Nalla RK, Kinney JH, Tomsia AP, Ritchie RO -2006-. Role of alcohol in the fracture resistance of teeth. J Dent Res85:1022–1026.

15.

Nanci A -2003-. Dentin-pulp complex. In: Ten Cate’s oral histology—development, structure and function. 6th ed. Chapter 8. St. Louis: Mosby, pp. 192–193.

16.

Oxlund H, Barckman M, Ortoft G, Andreassen TT -1995-. Reduced concentrations of collagen cross-links are associated with reduced strength of bone. Bone17-4 Suppl-:365S–371S.

17.

Oxlund H, Mosekilde L, Ortoft G -1996-. Reduced concentrations of collagen reducible crosslinks in human trabecular bone with respect to age and osteoporosis. Bone19:479–484.

18.

van der Graaf ER, ten Bosch JJ -1990-. The uptake of water by freeze-dried human dentin sections. Arch Oral Biol35:731–739.

19.

Wang MC, Pins GD, Silver FH -1994-. Collagen fibers with improved strength for the repair of soft tissue injuries. Biomaterials15:507–512.

20.

Wang X, Bank R, TeKoppele JM, Agrawal CM -2001-. The role of collagen in determining bone mechanical properties. J Orthop Res19:1021–1026.

21.

Wang X, Shen X, Li X, Agrawal CM -2002-. Age-related changes in the collagen network and toughness of bone. Bone31:1–7.

22.

Weadock KS, Miller EJ, Bellincampi LD, Zawadsky JP, Dunn MG -1995-. Physical crosslinking of collagen fibers: comparison of ultraviolet irradiation and dehydrothermal treatment. J Biomed Mater Res29:1373–1379.