Influence of soft-start curing protocol in the degree of conversion of a nanohybrid resin composite


  • Heloisa Amorim Periotto Graduate School of Dentistry, University of Fortaleza (UNIFOR)
  • Ana Daielly da Silva Graduate School of Dentistry, University of Fortaleza (UNIFOR)
  • Isabella Saraiva Leão de Resende Nucleus of Study and Research in Dental Biomaterials (NEPBiO), Graduate School of Dentistry, University Center of Christus (UNICHRITUS)
  • Hellen Martins Jucá Nucleus of Study and Research in Dental Biomaterials (NEPBiO), Graduate School of Dentistry, University Center of Christus (UNICHRITUS)
  • Sérgio Lima Santiago Department of Restorative Dentistry, Faculty of Pharmacy, Dentistry and Nursing, Federal University of Ceará (UFC)
  • Jiovanne Rabelo Neri University of Fortaleza



composite resins, polymerization, physical properties.


OBJECTIVE: To analyze the influence of the soft-start curing protocol in the degree of conversion of a nanohybrid composite.
METHODS: Ten specimens were prepared from the polymerization of the composite resin Llis using two protocols: conventional (1000 mW/cm² for 20 seconds) or gradual (250 mW/cm² for 20 seconds + 1000 mW/cm² for 15 seconds). Then, analyzes were performed using a spectrophotometer and data were subjected to Two-way ANOVA and Holm-Sidak test. The significance level was 5%.
RESULTS: There was no statistical difference between the average resin conversion degree of composite values in the base area and top for both curing protocols (p > 0.05).
CONCLUSION: Therefore, the use of soft-start curing protocol did not interfere in the degree of conversion of a nanohybrid composite.


Pallesen U, van Dijken JW. A randomized controlled 30 years follow up of three conventional resin composites in Class II restorations. Dent Mater 2015;31(10):1232-44.

Fronza BM, Rueggeberg FA, Braga RR, Mogilevych B, Soares LE, Martin AA, Ambrosano G, Giannini M. Monomer conversion, microhardness, internal marginal adaptation, and shrinkage stress of bulk-fill resin composites. Dent Mater 2015; 31(12):1542-51.

Ferracane JL, HiltonTJ. Polymerization stress is it clinically meaningful? Dent Mater 2016;32(1):1-10.

Selig D, Haenel T, Hausnerová B, Moeginger B, Labrie D, Sullivan B, Price R B. Examining exposure reciprocity in a resin based composite using high irradiance levels and real-time degree of conversion values. Dent Mater 2015;31(5):583-93.

Cekic-Nagas I, Egilmez F, Ergun G. The effect of irradiation distance on microhardness of resin composites cured with different light curing units. Eur J Dent 2010;4(4):440-6.

Ausiello P, Apicella A, Davidson CL. Effect of adhesive layer properties on stress distribution in composite restorations – a 3D finite element analysis. Dent Mater. 2002;95:295-303.

Lim BS, Ferracane JL, Sakaguchi RL, Conson JR. Reduction of polymerization contraction stress for dental composites by two-step light activation. Dent Mater 2002;18(6):436-44.

Sakaguchi RL, Peters MCRB, Nelson SR, Douglas WH, Poort HW. Effects of polymerization contraction in composite restorations. J Dent. 1992; 20(3):178-182.

Verluis A, Tantbirojn D. Theoretical considerations of contraction stress. Compend Contin Educ Dent 1999;1(25):24-32.

Dewaele M, Asmussen E, Peutzfeldt A, Munksgaard EC, Benetti AR, Finné G, Leloup G, Devaux J. Influence of curing protocol on selected properties of light-curing polymers: Degree of conversion, volume contraction, elastic modulus, and glass transition temperature. Dent Mater. 2009;25(12): 1576-84.

Chan DC, Browning WD, Frazier KB, Brackett MG.Clinical evaluation of the soft-start (pulse-delay) polymerization technique in Class I and II composite restorations. Oper Dent 2008;33(3):265-71.

Mehl A, Hickel R, Kunzelmann KH. Physical properties and gap formation of light-cured composites with and without “soft-start polymerization”. J Dent 1997;25(3-4):321-30.

Emami N, Soderholm KJM, Berglund LA. Effect of light power density variations on bulk curing of dental composites. J Dent 2003;31(3):189–96.

Aguiar FHB, Braceiro ALT, Ambrosano GMB, Lovadino JR. Hardness and diametral tensile strength of a hybrid composite resin polymerized with different modes and immersed in ethanol or distilled water media. Dent Mater 2005;21(12):1098-103.

Senawongse P, Pongprueksa P. Surface roughness of nanofill and nanohybrid resin composites after polishing and brushing. J Esthet Restor Dent 2007;19(5):265-73.

Ferracane JL, Matsumoto H, Okabe T. Time-dependent deformation of composite resins – compositional considerations. J Dent Res 1985;64(11): 1332-1336.

Caughman WF, Caughman GB, Shiflett RA, Rueggeberg F, Schuster GS. Correlation of cytotoxicity, filler loading and curing time of dental composites. Biomaterials 1991;12(8):737-40.

Rueggeberg FA, Craig RG. Correlation of parameters used to stimate monomer conversion in a light-cured composite. J Dent Res 1988;67(6): 932-7.

Par M, Lapas-Barisic M, Gamulin O, Panduric V, Spanovic N, Tarle Z.Long Term Degree of Conversion of two Bulk-Fill Composites. Acta stomatol Croa 2016;50(4):292-300.

Al-Zain AO, Eckert GJ, Lukic H, Megremis SJ, Platt JA. Degree of conversion and cross-link density within a resin-matrix composite. J Biomed Mater Res Part B 2017;8(00):1-9.

Resende ISL, Bonfim, AGM, Passos VF, Santiago SL. Avaliação indireta do grau de conversão de resina composta utilizando doisprotocolos de fotoativação. Rev abo Nac 2011;19(2):96-100.

Ferracane JL. Developing a more complete underestanding of stresses produced in dental composites during polimeryzation. Dent Mater 2005; 21:36-42.

Obici AC, Sinhoreti MAC, Sobrinho LC, Goes MF, Consani S. Evaluation of depth of cure and knoop hardness in a dental composite photo-activated using different methods. Braz Dent J 2004; 15(3):199-203.

Emami N, Soderholm KJM. How light irradiance and curing time affect monomer conversion in light-cured resin composites. EurJOral Sci 2003; 111(6):536-42.

Franco EB, Lopes LG. Conceitos atuais na polimerização de sistemas restauradores resinosos. Biodonto 2003;1(2):13-55.






Original Article