Laboratory investigation of Accuracy of Impression Materials for Border Molding

Introduction: Border molding of the edge of the individual impression tray is an important stage of prosthetic treatment of edentulous jaws, which often depends on the final result of the treatment. Classical thermoplastic impression materials for border molding have positive qualities that make them preferable by clinicians for their hardness, unlimited manipulation time and high impression sharpness. Modern silicone impression materials for border molding have long manipulating time and appropriate viscosity to allow dentists to perform functional tests.Aim: To determine the accuracy of different impression materials for border molding of individual impression trays.Materials and methods: Four impression materials for border molding were laboratory tested: Kerr impression compound green sticks and thermoplastic GC Iso functional sticks, additive type silicone Detaseal function and condensation type silicone sta-seal f. A modified individual impression tray designed by authors was used, allowing for laboratory load and stability. Ten impressions were taken and their formed edges were measured at 10 points three times - immediately after hardening/elasification, and 24 hours and 48 hours after hardening/elasification.Results: The results were analysed using ANOVA repetition analysis, where a statistically insignificant difference in the accuracy of three of the impression materials for border molding was established, except the C-type of silicone.Conclusions: Good manipulative qualities and measured accuracy in laboratory tests define these materials as very good for border molding procedures

Clinical Negative Pressure Measurement after Border Molding Procedure

Introduction: Border molding of the custom tray’s edge is an important stage in the treatment of an edentulous jaw that determines the stability of prosthesis at rest and function. Solid, thermoplastic and silicon impression materials may be used in border molding. After bolder molding procedure, the negative pressure between the custom tray and the prosthetic field is created. This is an informal indication for a good impression.Aim: To compare the negative pressure created after border molding procedure with different impression materials.Materials and methods: 35 patients (17 men and 18 women) aged 51 to 87 years with a complete edentulous upper jaw were examined. New clinical method for negative pressure measurement was created.  We used a special custom tray with palatal adaptor and a pump. Two groups of impression materials were tested:  thermoplastic (Kerr impression compound green sticks, GC Iso functional sticks) and silicones (Detaseal function, Sta-seal f). Statistical analysis was performed using ANOVA, confirmed by the absolute value analysis used to compare negative results, and a log transformation analysis for greater precision and also for negative data comparison.Results: A statistically significant difference was found between the two thermoplastic materials – GC Iso functional sticks and Impression compound green sticks. The mean group difference between these materials was 0.049 bars. There was no statistically significant difference between the other groups of materials.Conclusion: Quantitative measurement of negative pressure, created between the custom tray and the prosthetic field is entirely possible under clinical conditions

Laboratory Study of Color Stability of Different Types of Materials for Temporary Constructions

Introduction: A temporary construction serves as a preliminary representation of the type and appearance of a future permanent one that is tailored to the patient’s requirements. Like any prosthetic construction, it should meet the functional requirements, preserve or improve chewing and speech function. No matter how well maintained a prophylactic and functional prosthetic structure is, it will not be evaluated by the patient unless it retains and restores the existing shape, size and color of the natural teeth.Aim: To determine instrumentally to what extent different colorants change the color of temporary constructions.Materials and methods: Two materials for temporary restoration were tested – Protemp II and Protemp IV, of which a total of 100 test specimens, were fabricated. Under the equal storage conditions of room temperature and no direct access to sunlight, they were exposed to five 100-ml staining solutions: Coca-Cola, coffee (espresso), berry tea, orange juice and red wine in five separate containers. Measurements of color changes in the three areas of the tooth were performed using two spectrophotometric devices – Vita EasyShade and SpectroShade, at different time intervals – immediately before placement in the staining solution, at 1, 4, 7, and 14 days.Results: The results were analysed using the SPSS Statistical Processing Program (SPSS Inc., IBM SPSS Statistics) version 21.0. They were converted to a text file with the converter of the same program. In hypothesis testing, a standard value of p ≤ 0.05 was chosen for the level of significance that rejects the null hypothesis.Conclusion: Based on this study, the strong colouring effect of coffee and red wine on these restorations was demonstrated. We can conclude that Protemp IV material showed better color stability compared to Protemp II

VISCO-ELASTIC PROPERTIES OF SOFT RELINING MATERIALS – REVIEW

Despite the achievements of modern dentistry in fields of implantology and CAD-CAM technologies, the challenges associated with edentulous patients, treatment are still remaining. Difficulties are getting even greater, when it is a matter of highly atrophied alveolar ridges, covered with very thin mucosa, people suffering from xerostomia, exostosis, very well developed torus palatinus or tuberae maxillae. Problems of the patients with removable dentures usually are poor adhesion and stability, pain, wounds, difficult adaptation with the new dentures, etc. At this moment there are only two possibilities to help these people. The first one is the use of implants; the second one is to use soft relining materials. There are some obstacles that reduce the use of implants in all patients, because of medical, anatomical, psychological and financial concerns. While in the second option the contraindications are quite less

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

APPLICATION OF SOFT RELINING MATERIALS BY DENTISTS – A PILOT STUDY

Purpose: The aim of this study is to analyse the dentists, awareness of the soft relining materials – their behaviour, advantages and disadvantages. Materials and methods: A direct survey method was applied, as well as a documentary method of gathering statistical information. For the purpose of this investigation, a standard questionnaire has been presented, consisting of seven questions each. Results: The age group have no influence on the frequency of use of soft relining materials in practice. According to 49.57% of the interviewed dentists, the most frequently observed disadvantage is the hardening of these materials in a very short notice. Staining from food and beverage and frequently noticed bond failure from the denture basis were also observed, 18,26% consider discolouration from disinfectants a problem as well. The majority of the interviewed (56,52%) have been answered, that their patients are pleased from the applied SRM. 70,43% have been answered that SRM matches the denture basis and the rest 29,57% have been pointed out that these materials are not very aesthetic. Discussion: Although the majority of the dentists declare, that they are aware of the properties of the soft relining materials, they are a little bit sceptical about their use in practice. On the other hand, the patients are satisfied and find them very useful and beneficial. Conclusion: It can be concluded, that he majority of the dentists are very well acquainted with the soft relining materials, their purpose and way of application

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

EVALUATION OF MAXILLARY BONE DIMENSIONS IN SPECIFIC AREAS FOR REMOVABLE DENTURES

Background: The removable prosthetics is a big part of Prosthetic Dentistry. The prosthetic field is very important for successful treatment with partial or complete dentures. Maxillary bone is covered with soft tissues, but its anatomy is essential for retention, chewing stability and comfort of the patients. Purpose: The study’s aim was to evaluate the dimensions of maxillary bone in specific zones for removable dentures. Methods: Sixteen craniums were measured in 10 different zones. It was used an Electronic Digital Caliper 0-150 mm. Results: Consistently were applied F-test and Welch t-test for equality of variance and group’s comparison mean, respectively. The spread of the data was described by calculating range and standard deviation. The estimated value of range was highest in the FI-A1P, followed by FI-AC and FI-A2P. The smallest amplitude was established in the TM-PP and SNA. The estimated value of standard deviation was 2,57/2,51 in FI-AC zone, 2,46/2,59 in FI-A1P zone and a few smaller 2,08/2,13 in FI-A2P zone. The lowest values were in TM-PP and SNA areas. Conclusion: Tuber maxillae and Spina nasalis anterior have stable dimensions. The areas of canine and premolars are varied, because the zone is tasked by chewing function