Bond strength and ultimate tensile strength of resin composite filled into dentine cavity; effect of bulk and incremental filling technique

Nayif, Ma’an M.; Nakajima, Masatoshi; Foxton, Richard M.; Tagami, Junji

doi:10.1016/j.jdent.2007.12.006

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Volume 36, Issue 3 , Pages 228-234, March 2008

Bond strength and ultimate tensile strength of resin composite filled into dentine cavity; effect of bulk and incremental filling technique

Ma’an M. Nayif
- Cariology and Operative Dentistry, Department of Restorative Science, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-Ku, Tokyo 113-8549, Japan
- Corresponding author. Tel.: +81 3 5803 5483; fax: +81 3 5803 0195.
Masatoshi Nakajima
- Cariology and Operative Dentistry, Department of Restorative Science, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-Ku, Tokyo 113-8549, Japan
Richard M. Foxton
- Restorative Dentistry, King's College London Dental Institute at Guy's, King's College and St. Thomas’ Hospitals, King's College London, London, UK
Junji Tagami
- Cariology and Operative Dentistry, Department of Restorative Science, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-Ku, Tokyo 113-8549, Japan
- COE Program, FRMDRTB Tokyo Medical and Dental University, Tokyo, Japan

Received 25 September 2007; received in revised form 8 December 2007; accepted 22 December 2007.

Abstract

Objectives

The aim of this study was to evaluate the relationship between micro-tensile bond strength (μTBS) and ultimate tensile strength (UTS) of resin composite restorations in cavities filled by a bulk or incremental technique using the micro-tensile test.

Methods

Class I cavities (4mm long, 3mm wide, 3mm deep) were prepared into dentine of sixteen human molars. All cavities were bonded with Clearfil SE Bond and restored with AP-X composite with either a bulk or incremental technique. After storage in water for 24h, the teeth were vertically sectioned to yield two slabs. Each slab was sectioned into three sticks. Sticks of one slab were trimmed into an hourglass of 0.7mm² area at resin–dentine interface for bond strength measurement while the other sticks were trimmed at the centre of the restoration for UTS measurement. Specimens were tested in tension at 1mm/min until failure. The results obtained were statistically analysed using two-way ANOVA and post hoc test (α=0.05). Pearson's correlation test was used to identify any correlation between μTBS and UTS for each filling method.

Results

Both μTBS and UTS of resin composite decreased towards the bottom of the cavity (p<0.05). The bulk technique group presented lower μTBS than the incremental technique groups at all regions (p<0.05). In bulk filled restoration, there was a strong positive linear relationship between mean values of μTBS and UTS of resin composite based on the depth (r²=.99; p<0.05), while in incremental restoration there was no relationship between the variables.