Changes in the Surface Texture of Thermoplastic (Monomer-Free) Dental Materials Due to Some Minor Alterations in the Laboratory Protocol—Preliminary Study

Contemporary thermoplastic monomer-free prosthetic materials are widely used nowadays, and there are a great variety available on the market. These materials are of interest in terms of the improvement of the quality features of the removable dentures. The aim of this study is to establish how minimal changes in the laboratory protocol of polyamide prosthetic base materials influence the surface texture. Two polyamide materials intended for the fabrication of removable dentures bases were used—Perflex Biosens (BS) and VertexTM ThermoSens (TS). A total number of 20 coin-shaped samples were prepared. They were injected under two different modes—regular, as provided by the manufacturer, and modified, proposed by the authors of this study. Scanning electronic microscopy (SEM) under four magnifications—×1000, ×3000, ×5000, and ×10,000—was conducted. With minimal alterations to the melting temperature (5 °C) and the pressure (0.5 Bar), in Biosens, no changes in terms of surface improvement were found, whereas in ThermoSens, the surface roughness of the material significantly changed in terms of roughness reduction. By modifying the technological mode during injection molding, a smoother surface was achieved in one of the studied materials

NATURAL LANGUAGE PROCESSING AS A METHOD FOR EVALUATION OF FACTORS INFLUENCING SMILE ATTRACTIVENESS

Introduction: A drastic increase in the number of published medical papers per year is observed. This makes the identification, analysis and categorization of significant studies a difficult task. Natural (human) Language Processing and text mining are methods, part of the scientific branch computer linguistics that transfer the informational overload from a human to a computer. It enables easier processing and analysis of large volumes of unstructured textual data. Purpose: The current study aims to familiarize researchers working in the field of dentistry with the capabilities of NLP and TM for a quick and concise analysis of large volumes of unstructured textual information and identification of dependencies between different factors important for a given subject. Materials and Methods: To demonstrate the capabilities of text mining, an important topic in the field of dentistry was chosen – factors influencing the esthetics of a smile. The analysis was carried out with “R”- a computer language for statistical processing. A literature search was conducted in the “PubMed” database with key-words – “dental, esthetic and factor”. The resulting abstracts were saved as a local copy, imported and processed. Word frequencies and associations between different terms were analyzed. Results and discussion: Weak to moderate correlation was established between the significant, most frequent terms in the text - “esthetics, „smile“, „arc“, „buccal“, „gingival”, “lip” and “midline”./0.1<r<0.45/ Word combinations and frequencies resulting from the analysis are in agreement with other reported findings. Conclusion: NLP and text mining are valuable tools which decrease the time necessary for analysis of large volumes of data. The results can aid further research with increased accuracy

DEGREE OF AWARENESS OF SOFT RELINING MATERIALS BY DENTAL TECHNICIANS

The aim of the current investigation is to analyze the dental-technicians’ awareness of the soft relining materials, their characteristics, advantages, shortcomings and methods for relining. Materials and methods: For the purpose of this investigation a standard questionnaire has been presented. A direct survey method, documentary and statistical method, as well as graphical methods, including tables, charts, graphics and figures, were used. Data were analysed with the help of IBM SPSS Statistics (ver. 19). Results: One hundred and eight dental technicians were included in the survey, evenly distributed by gender. Removable and fixed prosthodontics is the most commonly mentioned spheres of dental activities. Almost all included in the investigation point out the laboratory relining method as the most frequently used. Acrylic and silicone SRM are the most used groups of relining materials. Change of colour and hardness are the most frequently noticed shortcomings of these materials. The majority of the dental technicians declare that they have never done replacement of SRM or the relining has lasted more than a year. Discussion: The correlation between the age and the years of labour service among the participants is quite obvious. Most of them start working soon after their graduation. Removable prosthodontics is among the priorities for the majority of the labs. Conclusion: Although their unambiguous advantages, the soft relining materials have lots of shortcomings as well. The major problems are connected with their change of colour and hardness. Nevertheless, the dental technicians find them useful and reliable in overcoming specific prosthetic problems

A SURVEY REGARDING THE AWARENESS OF THERMOPLASTIC RESINS AMONG BULGARIAN DENTISTS AND DENTAL TECHNICIANS

Thermoplastic materials (TMs) are used more than a century in dentistry worldwide, but in Bulgaria, there is limited information about their properties and indications. These materials let the specialists widen the application of full and partial dentures even in difficult clinical cases. Objective: A survey regarding the awareness of the properties, the drawbacks and the indications of the thermoplastic materials for dental purposes in Bulgaria. Material and method: Inquiry ranged from April 2016 until October 2016. The participants were 289 dentist and dental technicians in Bulgaria. The questions regard area of expertise, gender, age, years of experience; awareness of the types of TMs, members and working protocol; properties of the materials, personal observations of the participants. Results: Most of the participants work in a private practice, and half of them are familiar with the TMs in general. Conclusion: This study shows that 52% of the participants are aware of have some information about TM, 82% of them know the polyamides, 25% the thermoplastic acrylic resins, 15% polyoxymethylene, 4% polyolefin and only 1,5% Polyan. 42% use these materials in their practice and are familiar with the technological and working protocol and only 36% report that they are aware of their properties, disadvantages and indications

THE PLACE OF RETRACTION CORDS AMONG THE TISSUE DISPLACEMENT METHODS

Gingival displacement is performed to create sufficient space between the finishing line and the gingival tissue, to allow the injection of the adequate bulk of the impression material into the expanded crevice. Control of moisture in the sulcus is also necessary. The variety of methods for tissue management can be broadly classified into surgical and non-surgical. Objective: To analyse the properties of tissue displacement methods, described in the literature for the last 4 years and display the prefered choices of the practitioners. Material and method: A time range from the last 4 years was set. Using the keywords “retraction cord” and “survey,” we found 64 from 115 articles in total, relevant to our topic. Patents, citations and books weren’t included in this review. Results from the overview of the properties of the different tissue management methods indicate that retraction cords take a significant place among them and can be recognised as a classical and well known method. Conclusions: The studies from the articles show adequate sulcal width right after retraction with most methods, sufficient haemostasis can also be obtained. Every each method, however, is accompanied by several drawbacks. Concidering all the quallities of the different tissue dispalcent methods, there is no specific evidence to promote the use of a single technique over any other. The selection of the method for gingival retraction primarily depends on each clinical case. However, the retraction cord technique remains to be the prefered method for gingival management due to its many advantages