Effect of relining, water storage and cyclic loading on the flexural strength of a denture base acrylic resin

dos Santos Nunes Reis, José Maurício; Vergani, Carlos Eduardo; Pavarina, Ana Cláudia; Giampaolo, Eunice Teresinha; Machado, Ana Lucia

doi:10.1016/j.jdent.2005.10.001

« Previous Next »Journal of Dentistry
Volume 34, Issue 7 , Pages 420-426, August 2006

Effect of relining, water storage and cyclic loading on the flexural strength of a denture base acrylic resin

José Maurício dos Santos Nunes Reis
- Department of Dental Materials and Prosthodontics, São Paulo State University, UNESP, Araraquara Dental School, São Paulo, Brazil
- Present address: Avenida Feijó, No. 769 (Apto 14), Araraquara, SP, C.E.P. 14801-140, Brazil.
Carlos Eduardo Vergani
- Department of Dental Materials and Prosthodontics, São Paulo State University, UNESP, Araraquara Dental School, São Paulo, Brazil
- Present address: Rua Bento Ferreira Luis, No. 1814 (Casa 5), Araraquara, SP, C.E.P. 14806-590 Brazil.
- Corresponding author. Present address: Faculdade de Odontologia de Araraquara, UNESP, Rua Humaitá, No. 1680, Araraquara, São Paulo, C.E.P. 14801-903, Brazil. Tel.: +55 16 33016410; fax: +55 16 33016406.
Ana Cláudia Pavarina
- Department of Dental Materials and Prosthodontics, São Paulo State University, UNESP Araraquara Dental School, São Paulo, Brazil
- Present address: Avenida Espanha, No. 60 (Apto. 91), Araraquara, SP, C.E.P. 14801-130, Brazil.
Eunice Teresinha Giampaolo
- Department of Dental Materials and Prosthodontics, São Paulo State University, UNESP, Araraquara Dental School, São Paulo, Brazil
- Present address: Avenida José Bonifácio, No. 704 (Apto. 92-B), Araraquara, SP, C.E.P. 14801-150, Brazil.
Ana Lucia Machado
- Department of Dental Materials and Prosthodontics, São Paulo State University, UNESP, Araraquara Dental School, São Paulo, Brazil
- Present address: Rua Gonçalves Dias, No. 263 (Apto. 73), Araraquara, SP, C.E.P. 14801-290, Brazil.

Received 16 June 2005; received in revised form 12 September 2005; accepted 6 October 2005.

Abstract

Objectives

This study investigated the effect of relining, water storage and cyclic loading on the ultimate flexural strength (FS_U) and on the flexural strength at the proportional limit (FS_Pl) of a denture base acrylic resin (Lucitone 550-L).

Methods

Rectangular bars of L were made (64mm×10mm×2mm) and relined (1.3mm) with four relining resins (Kooliner-K, Ufi Gel Hard-UGH, Tokuso Rebase Fast-TR and New Truliner-NT). In addition, specimens relined with L and intact L specimens were made (64mm×10mm×3.3mm). A three-point flexural test was applied on the specimens (n=10) after (1) polymerization; (2) water storage (30 days); (3) cyclic loading (10,000 cycles at 5Hz) and (4) water storage (30 days)+cyclic loading. Data (MPa) were analyzed with three-way ANOVA and Tukey's HSD tests (α=0.05). To test for a possible correlation between FS_U and FS_Pl, a linear regression coefficient “r” was calculated.

Results

After water storage, L-UGH and L-TR demonstrated an increased FS_U (41.49–50.64MPa and 49.95–57.36MPa, respectively) (P<0.05). Only L-TR demonstrated an increased FS_Pl (20.58–24.21MPa) after water storage (P<0.05). L-L had the highest FS_U (between 78.57 and 85.09MPa) and FS_Pl (between 31.30 and 34.17MPa) (P<0.05). The cyclic loading decreased the FS_U and FS_Pl of all materials (P<0.05). Regression analysis showed a strong linear correlation between the two variables (r=0.941).

Conclusions

Water storage improved the FS_U of L-UGH and L-TR and the FS_Pl of L-TR. L-L produced the highest FS_U and FS_Pl. The FS_U and FS_Pl of all materials were detrimentally influenced by cyclic loading.

Keywords: Flexural strength, Acrylic resins, Relining, Water storage, Cyclic loading