Influence of the Manufacturing Method on the Adhesion of Candida albicans and Streptococcus mutans to Oral Splint Resins.

Andrea Schubert,Ralf Bürgers,Torsten Wassmann,Franziska Baum,Oliver Kurbad

doi:10.3390/polym13101534

Abstract

Microbial adhesion to oral splints may lead to oral diseases such as candidiasis, periodontitis or caries. The present in vitro study aimed to assess the effect of novel computer-aided design/computer-aided manufacturing (CAD/CAM) and conventional manufacturing on Candida albicans and Streptococcus mutans adhesion to oral splint resins. Standardized specimens of four 3D-printed, two milled, one thermoformed and one pressed splint resin were assessed for surface roughness by widefield confocal microscopy and for surface free energy by contact angle measurements. Specimens were incubated with C. albicans or S. mutans for two hours; a luminometric ATP assay was performed for the quantification of fungal and bacterial adhesion. Both one-way ANOVA with Tukey post hoc testing and Pearson correlation analysis were performed (p < 0.05) in order to relate manufacturing methods, surface roughness and surface free energy to microbial adhesion. Three-dimensional printing and milling were associated with increased adhesion of C. albicans compared to conventional thermoforming and pressing, while the S. mutans adhesion was not affected. Surface roughness and surface free energy showed no significant correlation with microbial adhesion. Increased fungal adhesion to oral splints manufactured by 3D printing or milling may be relevant for medically compromised patients with an enhanced risk for developing candidiasis.

Highlights

Oral splints are used in several fields of dental practice, including the treatment of temporomandibular disorders [1,2], the protection of teeth from excessive occlusal forces arising from parafunctional behaviors such as bruxism [3] and orthodontic tooth alignment [4].Conventional oral splint manufacturing is performed by the vacuum thermoforming or pressing of cold- or heat-cured acrylic resins, or by a combination of both
Specimens were incubated with C. albicans or S. mutans for two hours; a luminometric adenosine triphosphate (ATP) assay was performed for the quantification of fungal and bacterial adhesion
Increased fungal adhesion to oral splints manufactured by 3D printing or milling may be relevant for medically compromised patients with an enhanced risk for developing candidiasis

Summary

Introduction

Oral splints are used in several fields of dental practice, including the treatment of temporomandibular disorders [1,2], the protection of teeth from excessive occlusal forces arising from parafunctional behaviors such as bruxism [3] and orthodontic tooth alignment [4].Conventional oral splint manufacturing is performed by the vacuum thermoforming or pressing of cold- or heat-cured acrylic resins, or by a combination of both. Digital workflows involve intraoral scanning of dental arches, software-supported splint design and computer-aided splint manufacturing by additive or subtractive procedures [6,7,8]. Additive manufacturing by three-dimensional (3D) printing technologies is based on the light-induced polymerization of liquid resin monomers, forming solid objects layer by layer. Subtractive procedures are performed by computerized numerical control (CNC) devices milling objects from pre-fabricated, highly-polymerized resin blanks [9]. CAD/CAM manufacturing shows high accuracy, standardization and reproducibility, and is both time- and cost-efficient [6,9,10]. This has led to a continuous replacement of conventional splint manufacturing [6,11].

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Conclusion