Assessment of biofilm formation on dental prostheses using time-domain optical coherence tomography and atomic force microscopy

Date of Publication

8-6-2025

Document Type

Bachelor's Thesis

Degree Name

Bachelor of Science in Physics with Specialization in Medical Instrumentation

Subject Categories

Physics

College

College of Science

Department/Unit

Physics

Thesis Advisor

Maria Cecilia D. Galvez

Defense Panel Chair

Edgar A. Vallar

Defense Panel Member

Glenn G. Oyong
Ofelia T. Rempillo

Abstract (English)

This study quantitatively assessed Streptococcus mutans monospecies biofilm formation and antiseptic-induced reduction on acrylic resin, composite resin, and metal alloy substrates via extinction coefficient (EC) measurements obtained from a 1310 nm Time-Domain Optical Coherence Tomography (TD-OCT) system, complemented by Non-Contact Atomic Force Microscopy (NC AFM) for biofilm verification. Although biofilm matrices were not visually discernible in TD-OCT B-scans, NC-AFM confirmed biofilm presence through morphological features. The extinction coefficient values were estimated using a depth-resolved curve fitting model, where logarithmic signal intensities were fitted to characterize light attenuation through the samples. While this approach allowed relative comparisons across groups, the presence of filler particles in resin materials and the reflective geometry of stainless steel likely introduced multiple scattering events, leading to potential overestimations. Nonetheless, by applying the same model uniformly across all samples, the observed differences in EC values remained meaningful as indicators of biofilm-induced optical attenuation. Mean EC values generally increased following biofilm growth (Phase 1) and decreased after antiseptic treatment (Phase 2), particularly in acrylic and composite resin substrates, aligning with the expected optical attenuation behavior. However, only a subset of these changes reached statistical significance due to system noise, non-uniformity of sample geometry, and limited sample size. Stainless steel substrates showed inconsistent EC trends, likely influenced by the sample’s high surface curvature and reflective properties. The study has demonstrated the feasibility of using TD-OCT as a non-invasive method for detecting biofilm-induced optical changes, with NC-AFM providing complementary validation at the nanoscale. Together, these techniques highlight the potential for integrating OCT-based optical attenuation analysis with surface imaging approaches to assess and monitor biofilm formation.

Abstract Format

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Abstract (Filipino)

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Abstract Format

html

Language

English

Format

Electronic

Keywords

Attenuation (Physics); Biofilms; Dentures; Optical coherence tomography

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Embargo Period

9-1-2025

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