Scanning Electron Microscope Analysis of Internal Adaptation of Materials Used for Pulp Protection under Composite Resin Restorations

Authors

  • MARIA INEZ LEMOS PELIZ DDS, MS, PhD,

    1. Associate professor, Department of Prevention and Oral Rehabilitation, Federal University of Goias, Goiânia, Brazil
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  • SILLAS DUARTE Jr DDS, MS, PhD,

    Corresponding author
    1. Associate professor, Department of Restorative Dentistry at Araraquara School of Dentistry, University of São Paulo State (UNESP), Araraquara, São Paulo, Brazil; formerly visiting professor, Department of Restorative Sciences, University of Minnesota, Minneapolis, MN, USA
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  • WELLINGTON DINELLI DDS, MS, PhD

    1. Formerly associate professor, Department of Restorative Dentistry, UNESP, Araraquara, Sao Paulo, Brazil
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Reprint requests: Sillas Duarte Jr, DDS, MS, PhD, Sao Paulo State University at Araraquara—UNESP, Department of Restorative Dentistry, Division of Operative Dentistry, R:Humaitá, 1680, Araraquara, Sao Paulo, Brazil, CEP: 14801–903, CP: 331; e-mail: sillas01@yahoo.com.br

Abstract

ABSTRACT

Purpose::

The aim of this study was to evaluate the interfacial microgap with different materials used for pulp protection. The null hypothesis tested was that the combination of calcium hydroxide, resin-modified glass ionomer, and dentin adhesive used as pulp protection in composite restorations would not result in a greater axial gap than that obtained with hybridization only.

Materials and Methods:

Standardized Class V preparations were performed in buccal and lingual surfaces of 60 caries-free, extracted human third molars. The prepared teeth were randomly assessed in six groups: (1) Single Bond (SB) (3M ESPE, St. Paul, MN, USA); (2) Life (LF) (Kerr Co., Romulus, MI, USA) + SB; (3) LF + Vitrebond (VT) (3M ESPE) + SB; (4) VT + SB; (5) SB + VT; (6) SB + VT + SB. They were restored with microhybrid composite resin Filtek Z250 (3M ESPE), according to the manufacturer's instructions. However, to groups 5 and 6, the dentin bonding adhesive was applied prior to the resin-modified glass ionomer. The specimens were then thermo-cycled, cross-sectioned through the center of the restoration, fixed, and processed for scanning electron microscopy. The specimens were mounted on stubs and sputter coated. The internal adaptation of the materials to the axial wall was analyzed under SEM with × 1,000 magnification.

Results:

The data obtained were analyzed with nonparametric tests (Kruskal-Wallis, p V .05). The null hypothesis was rejected. Calcium hydroxide and resin-modified glass ionomer applied alone or in conjunction with each other (p < .001) resulted in statistically wider microgaps than occurred when the dentin was only hybridized prior to the restoration.

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