Colour changes of two thermoplastic resins used for flexible partial dentures

ABSTRACT

This study aims to evaluate the colour changes of two flexible resins used for manufacturing removable dentures, when in contact with colouring agents found in the diet. Twelve samples of iFlex™ by TCS® plus 12 samples of RocalFlex were placed in three solutions – coffee, curry and coca-cola. Colour measurements were performed using a PCE-CSM 5 colorimeter programmed in the CIE system (L* a* b*), before and after (24 h and 10 days) immersion in the solutions. Colour difference (ΔE*) was evaluated and the National Bureau of Standard (NBS) units were determined. Statistical analysis was performed using the IBM® SPSS® Statistics program. In the iFlex™ resin, there are statistically significant colour differences (p > 0.05) between the curry group and the control one after 24 h of immersion; on the 10th day, marked changes are observed in the curry group. In the RocalFlex resin, there are no statistically significant colour differences (p > 0.05) but marked changes are observed in the curry and coffee groups after 10 days of immersion. These thermoplastic resins did not exhibit colour stability when immersed in some potentially staining solutions, which may constitute a critical factor for the maintenance of the denture appearance and durability.

KEYWORDS:

• Flexible prosthesis
• polypropylene
• polyolefins
• colour stability
• thermoplastic materials
• removable prosthesis

Acknowledgments

The authors would like to thank Professor Jorge Lino (Faculty of Engineering of the University of Porto), for providing the colorimeter used; dental laboratory Dentalmar (Póvoa de Varzim, Portugal) for manufacturing the iFlex™ samples; and, RocalFlex for providing its resin.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Notes on contributors

Margarida Sampaio-Fernandes

Margarida Sampaio-Fernandes holds a degree in Dental Medicine (2009) and completed a PhD in the field of Dental Medicine (2016) focused on Implant Overdentures. She is an assistant professor in the Department of Removable Prosthodontics at Faculty of Dental Medicine of University of Porto since 2016. Her research interests include Prosthodontics, Overdentures, Implants and Biomaterials.

João Galhardo

João Galhardo has a Master Degree in Dental Medicine by Faculty of Dental Medicine of University of Porto (2019). His major field of interest is oral rehabilitation and his master thesis was developed on flexible resins. He also participated in congresses and courses related to his areas of interest.

Sandra Campos

Sandra Campos has a Master degree in Dental Medicine by Faculty of Dental Medicine of University of Porto (2019). Her major field of interest is oral rehabilitation and her master thesis was developed on thermoplastic materials. As pre-graduate dental student, Sandra Campos undertook multiple training and hands-on courses. Sandra has a former degree in Biomedical Sciences by University of Beira Interior (2014).

Susana João Oliveira

Susana João Oliveira is an assistant professor in the Department of Removable Prosthodontics at Faculty of Dental Medicine of University of Porto since 2017. Her research interests include Prosthodontics, Removable Partial Dentures and Biomaterials. Prior to the Master’s degree in Dental Medicine (2016), Susana Oliveira graduated in Biochemistry and completed a PhD in the field of Molecular Biology focused on ER stress and Hereditary Hemochromatosis.

José Carlos Reis-Campos

José Carlos Reis-Campos holds a degree in Dental Medicine (1981) and is an associated professor at Faculty of Dental Medicine of University of Porto (FMDUP) and Sub-Director of FMDUP since 2018. His research work, mainly focused on Oral Rehabilitation and Biomechanics. Part of this scientific work has been developed as researcher at Institute of Science and Innovation in Mechanical and Industrial Engineering (INEGI-UP) and as Member of the Steering Committee of Porto Biomechanics Laboratory (LABIOMEP).

Roberto C. Stegun

Roberto C. Stegun holds a degree in Dentistry from the University of São Paulo – USP 1979, a master’s degree in Dentistry (Dental Clinics) – USP 1990, a doctorate in Dentistry (Dental Materials) – USP 1996. He is an associate professor in the Department of Dental Prosthesis at the University of São Paulo since 2013. He has experience in Dentistry, with emphasis on Dental Prosthesis, acting on the following subjects: removable prosthesis, dental prosthesis, dental materials and research on removable prosthesis retention, with implants and attachment, and flexible thermoplastic materials for prosthesis, still the relationship Dentists/Dental Technician and surveys on dental absences. He is Coordinator of the Specialization Course at FUNDECTO - Fundação Faculdade de Odontologia and Vice Coordinator of the Envelhecer Sorrindo Program.

Maria Helena Figueiral

Maria Helena Figueiral holds a degree in Dental Medicine (1987) and is a full professor at Faculty of Dental Medicine of University of Porto (FMDUP) since 2013. Her research work is mainly focused on Prosthodontics and Oral Rehabilitation. Part of this scientific work has been developed as researcher at Institute of Science and Innovation in Mechanical and Industrial Engineering (INEGI-UP). The list of activities at FMDUP includes: Coordinator of the Specialization Course of Oral Rehabilitation (since 2011), Member of the Scientific Council, Member of the Scientific Committee of the PhD Course in Dental Medicine and Head of the Laboratory of Dental Prosthesis. MH Figueiral is also fellow of the International College of Dentists (ICD), Member of the General Council of Ordem dos Médicos Dentistas and President of the General Assembly of Sociedade Portuguesa de Estomatologia e Medicina Dentária.