Adhezija bakterije Streptococcus mutans na EVA, TPU in PETG folije : diplomsko delo

Lončar, Ira (author), Bohinc, Klemen (mentor), Hren, Doroteja (co-mentor), Zore, Anamarija (co-mentor), Lampe, Tomaž (reviewer)

Uvod: Zaradi naraščanja potrebe po estetski ortodontski obravnavi so se predvsem za namene uporabe v zobozdravstvu pojavili in pričeli uporabljati termoplastični prozorni materiali v obliki folij za termo oblikovanje. Izdelki se okoli pacientovega zobovja tesno prilegajo, v ustni votlini pa se lahko nahajajo tudi po dvanajst ali več ur dnevno. Ker se v oralni mikroflori nahajajo različni mikroorganizmi, ki jim površine, primerne za adhezijo, ne predstavljajo samo strukture ustne votline, ampak tudi tujki, bo biofilm nastal tudi na termoplastičnih materialih. Na adhezijo bakterij in nastanek biofilma vplivajo različni dejavniki, med njimi tudi fizikalno-kemijske lastnosti materiala, kot so hrapavost, hidrofilnost in naboj površine. Bakterija, ki je opredeljena kot najbolj patogeni dejavnik pri nastanku kariesa, je Streptococcus mutans (S. mutans). Namen: Namen diplomskega dela je ugotoviti, kakšna je adhezija bakterije S. mutans na EVA, TPU in PETG materiale ter kako nekatere fizikalno-kemijske lastnosti vplivajo na njeno adhezijo. Metode dela: Iz materialov EVA, TPU in PETG, ki se uporabljajo kot folije za termo oblikovanje, smo pripravili preizkušance velikosti 1 cm x 1 cm ter velikosti 1 cm x 2 cm. V mikrobiološkem laboratoriju smo vzorce sterilizirali in pripravili čisto kulturo bakterije S. mutans, ki smo jo adherirali na preizkušance, stopnjo adhezije pa nato opazovali z vrstičnim elektronskim mikroskopom. Poskus adhezije smo izvedli trikrat. Vsem površinam smo analizirali fizikalne lastnosti, kot so hrapavost površine, mejni kot in naboj površine. Hrapavost smo merili dvakrat. V laboratoriju za ortodontijo na Stomatološki kliniki smo iz enakih materialov, ki smo jih raziskovali, izdelali bruksistično opornico, enostavni športni ščitnik ter folijo za doseganje premikov zob. Rezultati: Največji mejni kot smo izmerili pri materialu EVA (78,98° ± 5,81°), najmanjši mejni kot je bil izmerjen pri materialu PETG (70,64° ± 5,14°). Najbolj negativen naboj smo izmerili pri materialu PETG (-38,20 mV ± 0,46 mV), najmanj negativnega pa na površini TPU (-14,20 mV ± 1,01 mV). Najbolj hrapavo površino smo izmerili pri materialu EVA (0,20 µm ± 0,15 µm), sledil mu je TPU (0,14 µm ± 0,04 µm), najbolj gladko površino pa smo izmerili pri materialu PETG (0,06 µm ± 0,03 µm). Povprečni delež površine vidnega polja pokritega z bakterijami, izračunan iz treh poskusov adhezije, je za material EVA znašal 0,35 % ± 0,44 %. Za material TPU je povprečni delež z bakterijami pokrite površine, izračunan iz treh poskusov adhezije znašal 5,47 % ± 0,25 %. Za material PETG je povprečni delež površine pokrite z bakterijami, izračunan iz treh poskusov adhezije znašal 50,84 % ± 22,65 %. Razprava in zaključek: rezultati študije kažejo, da je stopnja bakterijske adhezije največja na najbolj gladkem materialu (PETG) ter najmanjša na najbolj hrapavem materialu (EVA). Na material z najbolj negativno nabito površino (PETG) se je adheriralo največ bakterij, material z najmanj negativno nabito površino (TPU) pa je imel drugi največji delež površine pokrite z bakterijo S. mutans. Kakšen je vpliv mejnega kota na adhezijo S. mutans težko določimo, saj so bili izmerjeni mejni koti za vse tri materiale so podobno veliki. Razliko v deležu površine (%), pokritem z bakterijami, ki se pojavlja med tremi poskusi adhezije bi lahko pripisali nezadostnemu število zajetih SEM slik iz katerih smo določali % pokritosti.

• Language: Slovenian
• Keywords: diplomska dela, laboratorijska zobna protetika, EVA, TPU, PETG, Streptococcus mutans, adhezija bakterij, hrapavost, naboj površine, mejni kot
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: ZF - Faculty of Health Sciences
• Place of publishing: Ljubljana
• Publisher: [I. Lončar]
• Year: 2022
• Number of pages: 33 str., [5] str. pril.
• PID: 20.500.12556/RUL-142254
• UDC: 616.31
• COBISS.SI-ID: 127476739
• Publication date in RUL: 28.10.2022

Secondary language

• Language: English
• Title: Adhesion of the bacteria Streptococcus mutans to EVA, TPU and PETG foils : diploma work

Abstract

Introduction: With the growing need for aesthetic orthodontic treatment, thermoplastic transparent materials in the form of thermoforming foils began appearing for treatment purposes in dentistry. The products fit tightly around the patient's teeth, and can be worn by the patient for twelve or more hours a day, thus providing suitable surfaces for bacterial adhesion. Bacterial adhesion and biofilm formation are influenced by various factors, including the physico-chemical properties of the material, such as roughness, hydrophilicity and surface charge. The bacterium identified as the most pathogenic factor in the formation of caries is Streptococcus mutans (S. mutans). Purpose: Purpose of this diploma work is to determine the adhesion of the bacterium S. mutans to EVA, TPU and PETG materials, and to discover how certain physico-chemical properties affect its adhesion. Methods: For this study, 1 cm x 1 cm and 1 cm x 2 cm test pieces were prepared from EVA, TPU and PETG thermoforming foils. All samples were sterilized and a pure culture of S. mutans bacteria was prepared in the microbiological laboratory. S. mutans was adhered to the test specimens, and the degree of adhesion was then observed with a scanning electron microscope. The adhesion test was done three times. We analyzed the physical properties of all surfaces, such as surface roughness, contact angle and surface charge. Roughness was measured twice. In the orthodontic laboratory in Stomatološka klinika in Ljubljana, we made different kinds of appliances from the same materials that we researched. Results: The largest contact angle was measured on EVA (78,98° ± 5,81°), the lowest contact angle was measured on PETG (70,64° ± 5,14°). The most negative charge was measured on PETG (-38,20 mV ± 0,46 mV) and the least negative was measured on the TPU surface (-14,20 mV ± 1,01 mV). The material with the roughest surface is EVA (0,20 μm ± 0,15 μm), followed by TPU (0,14 μm ± 0,04 μm), the smoothest surface was measured on PETG (0,06 μm ± 0,03 µm). The mean percentage for surfage covered in bacteria of EVA material calculated from three adhesion experiments was 0,35 % ± 0,44 %. For TPU material the mean percentage for surfage covered in bacteria of TPU material calculated from three adhesion experiments was 5,47 % ± 0,25 %. For PETG material this percentage was 50,84 % ± 22,65 %. Discussion and conclusion: The results of the study show that the most S. mutans bacteria were adhered on the smoothest material (PETG) and the least on the roughest material (EVA). The material with the most negatively charged surface (PETG) had the highest coverage of S. mutans, the material with the least negatively charged surface (TPU) had the second highest area coverage of S. mutans. The influence of the contact angle on the adhesion of S. mutans is difficult to determine, since the measured contact angles for all three materials are similarly large. The difference in the percentage of the surface (%) covered by bacteria that occurs between the three adhesion experiments could be attributed to the insufficient number of captured SEM images from which the % coverage was determined.

• Keywords: diploma theses, laboratory dental prosthetics, EVA, TPU, PETG, Streptocccus mutans, bacterial adhesion, roughness, surface charge, contact angle