The longevity and success of dental composite restorations rely heavily on the integrity of the interface between the composite material and the surrounding tooth enamel. This interface is susceptible to various challenges, including thermal shock, which can lead to microleakage, marginal staining, and ultimately, restoration failure. This abstract explores the detrimental effects of thermal shock on the enamel-composite interface, highlighting the underlying mechanisms and potential preventive measures.

Dental composite restorations are widely used for restoring tooth structure compromised by caries, fractures, or other defects. While offering aesthetic advantages and minimal tooth removal, their long-term success hinges on a strong and durable bond with the surrounding tooth structure. The enamel-composite interface plays a crucial role in this regard, acting as a barrier against bacterial infiltration, marginal staining, and sensitivity. However, this interface is vulnerable to degradation from various factors, including thermal shock.

Thermal shock refers to the rapid and significant change in temperature experienced by a material. In the context of dental restorations, this can occur due to the consumption of hot or cold beverages, exposure to inhaled air, or smoking. These rapid temperature fluctuations can induce stresses within the tooth structure and the composite material due to their differing thermal expansion coefficients. Over time, repeated thermal cycling can lead to microcracks, gaps, and deterioration at the enamel- composite interface.

The detrimental effects of thermal shock on the enamel-composite interface can be attributed to several mechanisms:

Differential Thermal Expansion: Enamel and composite materials possess varying thermal expansion coefficients. During thermal shock, the differential expansion rates can create internal stresses within the interface and the surrounding tooth structure. These stresses can manifest as microcracks and debonding at the interface.

Bond Strength Degradation: The adhesive bond between the composite and enamel can weaken due to thermal shock. The rapid temperature changes can compromise the integrity of the adhesive layer, leading to microleakage and potential bacterial infiltration.

Fracture of Brittle Materials: Enamel and some composite materials are inherently brittle. Thermal shock can exacerbate the inherent brittleness of these materials, leading to microfractures and chipping at the interface.

Thermal shock, Enamel-composite interface, Dental restoration

Çelik Köycü B, İmirzalıoğlu P. Heat transfer and thermal stress analysis of a Mandibular molar tooth restored by different indirect restorations using a three-dimensional finite element method. J Prosthodont, Nov 30; 2015.

Messersmith PB, Obrez A, Lindberg S. New acrylic resin composite with improved thermal diffusivity. J Prosthet Dent. 1998; 79:278-84.

Bodzenta J, Burak B, Nowak M, et al. Measurement of the thermal diffusivity of dental filling materials using modified Angström's method. Dent Mater. 2006;22:617-21.

International Organization for Standardization. Dental materials—testing of adhesion to tooth structure. ISO/TS 11405, WHO, Geneva, Switzerland; 2003.

Blumer L, Schmidli F, Weiger R, et al. A systematic approach to standardize artificial aging of resin composite cements. Dent Mater. 2015;31:855-63.

Kenneth A. Phillips science of dental materials, twelfth ed. Saunders; 2013.

Lin M, Liu QD, Kim T, Xu F, Bai BF, Lu TJ. A new method for characterization of thermal properties of human enamel and dentine: Influence of microstructure. Infra Phys Tech. 2010;53:457–463.

Fenner DN, Robinson PB, Cheung PM. Three-dimensional finite element analysis of thermal shock in a premolar with a composite resin MOD restoration. Med Eng Phys. 1998;20:269-75.

Morresi AL, D'Amario M, Capogreco M, et al. Thermal cycling for restorative materials: Does a standardized protocol exist in laboratory testing? A literature review. J Mech Behav Biomed Mater. 2014;29:295-308.

Lin M, Xu F, Lu TJ, et al. Review of heat transfer in human tooth--experimental characterization and mathematical modeling. Dent Mater. 2010b;26:501-13.

Turkistani A, Sadr A, Shimada Y, et al. Sealing performance of resin cements before and after thermal cycling: Evaluation by optical coherence tomography. Dent Mater. 2014;30:993-1004.

Al-Harbi F, Kaisarly D, Michna A, et al. Cervical interfacial bonding effectiveness of class II bulk versus incremental fill resin composite restorations. Oper Dent, Jul 7; 2015.

Little PA, Wood DJ, Bubb NL, et al. Thermal conductivity through various restorative lining materials. J Dent. 2005;33:585-91.

Versluis A, Douglas WH, Sakaguchi RL. Thermal expansion coefficient of dental composites measured with strain gauges. Dent Mater. 1996;12:290-4.

Casselli DS, Worschech CC, Paulillo LA, et al. Diametral tensile strength of composite resins submitted to different activation techniques. Braz Oral Res. 2006;20:214-8.

Vaidyanathan J, Vaidyanathan TK, Wang Y. Thermoanalytical characterization of visible light cure dental composites. J Oral Rehabil. 1992;19:49-64.

Chen WC, Ko CL, Wu HY, et al. Thermal cycling effects on adhesion of resin-bovine enamel junction among different composite resins. J Mech Behav Biomed Mater. 2014; 38:105-13.

Kellerhoff RK, Fischer J. In vitro fracture strength and thermal shock resistance of metal- ceramic crowns with cast and machined AuTi frameworks. J Prosthet Dent. 2007;97:209-15.

Lopes MB, Yan Z, Consani S, et al. Evaluation of the coefficient of thermal expansion of human and bovine dentin by thermomechanical analysis. Braz Dent J. 2012;23:3-7.

Nica I, Rusu V, Cimpoeşu N, et al. Thermal and structural properties of nano- and micro- filled composites. Rev Med Chir Soc Med Nat Iasi. 2009;113:892-8.

Sideridou I, Achilias DS, Kyrikou E. Thermal expansion characteristics of light-cured dental resins and resin composites. Biomaterials. 2004;25:3087-97.

Ghulman MA. Effect of cavity configuration (C factor) on the marginal adaptation of low- shrinking composite: A comparative ex vivo study. Int J Den. 2011;159749.

Heintze SD, Zimmerli B. Relevance of in vitro tests of adhesive and composite dental materials. A review in 3 parts. Part 3: In vitro tests of adhesive systems. Schweiz Monatsschr Zahnmed. 2011;121:1024-40. Review.