Light-cured Composite Materials Research Articles

Long-term results of aesthetic and functional restoration of frontal teeth in young people with preserved systemic and dental health

AIM. To analyze the stability of the results of aesthetic and functional restoration of frontal teeth in young people with preserved systemic and dental health based on expert assessments and subjective conclusions of the patient.MATERIALS AND METHODS. The quality preservation of 63 composite restorations of frontal teeth performed a year ago in 54 patients aged 19–27 years with preserved systemic and dental health was analyzed by experts using the Ryge international assessment system. The calculation of integral and scale indicators of the dental index “Oral Health Impact Profile” OHIP-14-aesthetic-RU supplemented the selfassessment of the quality of previously performed dental restoration treatment in the smile area.RESULTS. In 12 months after the restoration treatment most composite restorations corresponded to high aesthetic and functional characteristics in terms of the quality of preservation of the restored anatomical shape (respectively 70.0–61.5%), texture and color of the surface (66.7–65.4%) and edge fit (66.7–65.4%). The largest number of unacceptable assessments of the quality of restoration of III-IV classes were obtained according to the criteria of “Edge fit” (6.7% and 15.4%, respectively) and “Surface quality” (6.7%). The absolute majority (96.4%) of patients are satisfied with the quality of previously performed restoration and their preservation, which was confirmed by both professional opinions of dental experts and indicators of the aesthetically oriented dental quality of life index OHIP-14-aesthetic RU (the integral indicator was 5.92 ± 1.31 points), comparable with the index values in healthy young people with an intact dentition.CONCLUSIONS. The use of modern light-curing composite materials for the treatment of carious defects of anterior teeth makes it possible to achieve high aesthetic and functional results of restoration according to its comprehensive (objective / subjective) assessment in the long-term follow-up.

MORPHOLOGICAL CHANGES OF RAT PERIODONTIUM IN SUPRAOCCLUSAL RELATIONS OF INDIVIDUAL TEETH IN THE AGE ASPECT

Although the issue of the occlusal load influence on the occurrence of pathological phenomena in the body has been discussed for decades, it is still a subject of debate. Pathogenic occlusion is defined as excessive occlusal forces (premature contacts and interference) that can cause injuries to the dentition, including teeth and periodontal tissues. Changes in occlusal dimensions, if not properly performed or treated, can lead to dysfunctions of the dentition, such as joint clicking, difficulty in chewing, occlusal discomfort, muscle fatigue, and pain.
 Aim: to determine the morphological changes of periodontium in rats of different age groups in the supraocclusal relationship of individual teeth in the age aspect.
 Materials and methods of the study. The study was conducted on 60 white laboratory rats aged 4 to 22 months and weighing 90 to 330 g. The rats were divided into control (30 animals) and experimental (30 animals) groups. Each group was divided into 3 subgroups (10 animals each) depending on the age of the rats: young, mature and senile. Young animals included rats aged 3 4 months with a weight of 90 100 g; mature animals aged 6-8 months with a weight of 150 170 g; senile rats 20 22 months and weighing 200 220 g. In the experimental group, the state of supraocclusion was modeled by increasing the height of the lower right second molars by placing 1 mm high filling. For the placement of the filling, 37% orthophosphorus etching gel for enamel and dentin (Latus, Ukraine), microapplicators (Latus, Ukraine), the fifth generation Prime&Bond NT adhesive system (Dentsply Sirona, Germany), the universal microhybrid light-curing composite material Latelux (Latus, Ukraine) and the photopolymerizer LED.D (WOODPECKER, China) were used according to the manufacturer's instructions. The experimental animals were withdrawn from the experiment on the 15th day by decapitation under general anesthesia with sodium thiopental. The lower jaws were skeletonized, and dental blocks were cut out in the area of the molars. For histological examination, the dental blocks were fixed in a 10% solution of neutral formalin for two days, dehydrated in alcohols of increasing concentration and embedded in paraffin. Then, sections were made from the obtained preparations on a Shandon Finesse 325 rotary microtome with a section thickness of 4-6 μm. The histological sections were fixed on degreased slides and dried. Van Gieson staining was performed. The width of the periodontal gap was determined using the ZEISS ZEN 3.7 program by Carl Zeiss Microscopy.
 Results of the study. Histometric analysis has showed significant morphological changes in the experimental group of all age categories. In young rats, the fibrinoid edema phenomena of the periodontal ligament collagen fibers were observed. In mature rats, there was a picture of mucoid edema of collagen fibers of the periodontal ligament. In senile rats, fibrinoid necrosis of collagen fibers of the periodontal ligament were discovered, an inflammatory infiltrate, macrophages and neutrophils, with a predominance of neutrophilic inflammatory microenvironment, and initial hyaline tissue changes were found. In all age groups, there was cement resorption on the lateral surfaces of the tooth root, lacunar resorption of alveolar bone tissue and the presence of a large number of osteoclasts. In senile rats, hypercementosis was determined in the apical part of the root. In the control group of all age categories, neither resorption nor disorganization of connective tissue, nor hypercementosis was detected.
 Conclusions. The study shows that traumatic occlusion leads to resorption of root and alveolar cementum in all age groups. In young rats, traumatic occlusion causes fibrinoid edema of collagen fibers of the periodontal ligament. In mature rats, traumatic occlusion causes mucoid edema of collagen fibers of the periodontal ligament. In senile rats, traumatic occlusion causes fibrinoid necrosis of collagen fibers of the periodontal ligament, initial hyaline tissue changes and hypercementosis.

Investigation of the surface of light-curing dental materials after pre-polymerization heating

Despite the great variety and wide application of light-cured composite restorative materials for the treatment of hard tissue diseases, the issue of longevity of restorations remains relevant to this day. One of the criteria for the long-term durability of a composite restoration is the finish of the restoration. Poor polishing and surface roughness significantly reduce theservice life of the restoration and provide a good environment for biofilm adhesion, loss of luster of the restoration, and caries recurrence. Thus, methods affecting the reduction of surface relief in restorations remain a current issue. Aim. To evaluate the surface roughness and porosity of composite filling materials after pre-polymerization heating. Materials and methods. Sixty composite samples were prepared in the form of 1 mm thick, 1.2 cm diameter disks. The samples were divided into 2 groups depending on the presence of pre-polymerization heating. Atomic force microscopy (AFM) was used to measure the roughness and to visualize the surface morphology of the samples. Porosity was measured using a vacuum sputtering unit, and a scanning electron microscope was used to obtain micrographs of the sample. Results. The use of pre-polymerization heating of composite filling materials in dental practice will allow dentists to significantly reduce the expression of the relief of the composite restoration by reducing the roughness and pore volume in the matrix of the composite filling material, which will certainly optimize the finishing of the restoration. Conclusions. Pre-polymerization heating has a positive effect on the surface topography of the composite restoration, reducing its roughness and porosity, which improves the stage of finishing: obtaining a dry gloss, ensuring the duration of color stability, as well as reducing the adhesion of microorganisms to the filling material, thereby increasing the longevity of the composite restoration.

COMPARATIVE ANALYSIS OF THE EFFECT OF ADHESIVE SYSTEMS ON THE MICROELEMENT COMPOSITION OF THE DENTIN OF THE CROWN PART OF THE TOOTH

Title: Comparative analysis of the effect of adhesive systems on the microelement composition of the dentin of the crown part of the tooth. Purpose: To research the microelement composition of the «filling-tooth» interactive zone, the morphological characteristics of its border, to assess the effect of adhesive systems of the V and VII (self-etching) generations on the ion-exchange composition of the dentin of the crown part of the tooth, and to qualitatively assess the microelement composition of the hybrid dentin zone. Materials and methods: Extracted teeth with preserved crown part (n=20), enamel etching gel (Vladmiva), V generation Singlebond - 2 adhesive system (3M ESPE), self-etching adhesive system Prime-Bond Universal (Dentsply Sirona), light-cured composite material Migrofil (Republic of Belarus). The research of the microstructure of samples with formed and sealed Class I cavities according to Black was carried out on a certified high-resolution scanning electron microscope «Mira» by Tescan (Czech Republic). The research of the microelement composition of the «filling-tooth» border was carried out by X-ray spectral analysis, which consisted of 2 blocks: using the adhesive system of the fifth generation and the seventh generation of the adhesive system. Conclusions: 1. A comparative analysis of the results of using the fifth-generation adhesive system and the selfetching adhesive system showed that when using the total etching technique, trace elements Ca and P migrate from the tooth dentin structure into the hybrid zone. When using the adhesive system VII, the migration of elements was not established, due to the lack of demineralization of the dentin structure and the modification of the smeared layer. 2. Qualitative assessment of planar spectrograms revealed an increase in the carbon element in the modified adhesive layer. which is due to the presence of a smeared layer after odontopreparation of hard tissues of teeth destroyed by a carious process 3. The migration of the Si element indicates the chemical interaction of the adhesive and the filling material, as well as the filling material and the dentin of the tooth through the adhesive layer. 4. The use of the adhesive system of the fifth generation provides a higher quality of the marginal fit of the filling material to the surface of the dentin than when using a self-etching adhesive system.

Investigation of new light-cured composite dental materials by atomic absorption spectroscopy

The paper the study of new light-cured composite dental materials by atomic absorption spectroscopy are considered. High-quality aesthetics, durability, functionality and maximum preservation of hard dental tissues are the result of new adhesive preparation and improvement of the physico-chemical and optical properties of composites, therefore, the study of the optical properties of composites is relevant and promising. The article the objects under study, the appearance of the spectrophotometer, the optical scheme and the technical characteristics of the device are presented. In the study of restorative dental composites, different absorption capacity of materials was obtained. Maximum absorption in all composite materials in the wavelength range = 250…360 nm was detected.

THE EFFECT OF SERVISE LIFE ON THE WATER ABSORPTION PARAMETER OF LIGHT CURING COMPOSITE RESIN MATERIALS

Introduction. Water absorption is one of the important properties of light-curing composite resin materials used in dentistry for tooth restoration. Water absorption refers to the ability of a material to absorb water and can affect its mechanical and aesthetic properties.
 Aim. To find out whether the service life of the composite material has an effect on the water absorption parameter.
 Materials and methods. Light-curing composite resin Latelux (Latelux), manufactured by Latus, Ukraine, was chosen as the material for study. Two groups, test and control groups, were formed. The first group included samples of material with an expired service life (expired before 2018). The samples were dried in a desiccator and weighed, then placed into a thermostat with distilled water for 7 days, then removed and weighed to determine water absorption. Calculations were performed in MS Excel 2013 using the formula W: (m2-m3)/V (μg/mm3).
 Results. After calculating the obtained results, the water absorption of the samples with an expired shelf life was on average 3.55±0.9 µg/mm3, while the composite with a normal shelf life was 4.9±1.8 µg/mm3. All samples passed the test, i.e. their parameter did not exceed 40 μg/mm3 according to ISO standards. Statistically obtained data did not reveal a relationship between the shelf life of the composite and its water absorption (p=0.464). The thickness of the composite material also has no statistical significance on the water absorption of the composite either in the experimental (p=0.26) or in the control group (p=0.378).
 Conclusions. Based on the results of our own research, as well as data from literary sources, we can conclude that the shelf life does not have a significant impact on the water absorption rate of the Latelux composite material.

In Vitro Fracture Resistance of Endodontically Treated Premolar Teeth Restored with Prefabricated and Custom-Made Fibre-Reinforced Composite Posts.

(1) Background: The study aimed to compare and analyse the differences between the features of prefabricated fibre-reinforced composite (FRC) posts and custom-made FRC posts in the form of a tape and confirm the necessity of using FRC posts in teeth treated endodontically in comparison to direct reconstruction with a composite material. (2) Methods: Sixty premolars after endodontic treatment were used. The teeth were divided into four groups (n—15). Group 1: teeth with embedded prefabricated posts (Mirafit White); group 2: teeth with embedded prefabricated posts (Rebilda); group 3 teeth with embedded custom-made posts in the form of a tape (EverStick); group 4: teeth without a post restored with composite material. The compressive strength of the teeth was tested using the Instron-5944 testing machine until the sample broke. The crystal structure of the investigated posts was detected with the X-ray diffractometer (3) Results: During the experiment, the maximum values of forces at which the damage of the restored premolar teeth after endodontic treatment occurred were obtained. The best results were obtained for teeth rebuilt with Rebilda Posts (1119 N), while teeth with cemented Mirafit White posts were the weakest (968 N). Teeth without an embedded FRC post, rebuilt only with light-cured composite material, obtained the lowest value—859 N. (4) Conclusions: The use of FRC posts increases the resistance to damage of an endodontically treated tooth when compared to direct restoration with light-cured composite material.

Contact-former to restore the age-related characteristics of the contact pads of the posterior teeth

The aim of the study: development and clinical testing of specialised dental instruments and a clinical protocol for the restoration of the age-re-lated characteristics of contact pads during caries treatment of the contact surfaces of posterior teeth applying aesthetic restoration using light-cured composite materials.Materials and research methods. A contact-former of an original design and a medical-technological algorithm for the formation of contact areas of the posterior teeth, taking into account age characteristics, have been developed. A comprehensive assessment of the quality of 289 direct composite restorations of posterior teeth with Class 2 defects according to Black made during the treatment of dental caries in 178 pa-tients aged 20 to 59 years was performed. The condition of 162 composite restorations performed using contact-formers and 127 composite restorations performed using the traditional restoration technique, without the use of contact-formers and other similar tools and techniques.Research results. The compliance of the restorations performed using the developed technique, according to the criteria for restoration of the contact surfaces of the teeth (4 points), was 98.3 ± 1.02% after 7 days after treatment, 92.5 ± 2.07% after 12 months, and 24 months after – 74.8 ± 3.41%. In the comparison groups, 16.3 ± 3.28% (p<0.005) restorations were fully consistent with the clinical requirements for this indicator (4 points) 7 days after treatment, 11.3 ± 2.81% (p<0.005) after 12 months, after 24 months this indicator decreased to 9.8 ± 2.64% (p<0.005).Conclusion. The data obtained make it possible to recommend the use of a contact-former of the original design and the method of restor-ing planar contact points (contact pads) taking into account age-related characteristics within the framework of a personalized approach in the treatment of patients with caries of the contact surfaces of posterior teeth by the method of direct aesthetic restoration with light-cured composite materials.

ЛАБОРАТОРНОЕ ИССЛЕДОВАНИЕ ЭФФЕКТИВНОСТИ ВОССТАНОВЛЕНИЯ ВОЗРАСТНЫХ ОСОБЕННОСТЕЙ КОНТАКТНЫХ ПОВЕРХНОСТЕЙ БОКОВЫХ ЗУБОВ МЕТОДОМ ПРЯМОЙ КОМПОЗИТНОЙ РЕСТАВРАЦИИ

The methods of aesthetic restoration of posterior teeth with composite materials currently used in practical dentistry make it possible to create only a point contact, which does not correspond to the age characteristics of the patients' teeth, therefore, it is important to develop methods for creation and positioning the contact areas, taking into account the age characteristics of structures of the teeth. A laboratory study of the effectiveness of the method of recreation of the age-related characteristics of the contact areas of the posterior teeth using the method of direct aesthetic restoration using light-cured composite materials with a specially developed tool – a contact-former was carried out. Phantom models were used to evaluate the significant characteristics of 40 restorations of posterior teeth with cavities of class 2 according to Black, performed in accordance with the traditional method, 80 restorations performed in accordance with the developed algorithm for restoring the contact points of posterior teeth by the method of direct composite restoration, taking into account age characteristics: 40 restorations with using a contact former with a working part of 1×2 mm (S = 2 mm2), 40 restorations - using a contact former with a working part of 1.5×3 mm (S = 4.5 mm2). It was found that the usage of the approved method of restoration of the contact points of posterior teeth using the method of direct composite restoration, taking into account age characteristics with the use of a contact-former in the process of tooth restoration, allows to obtain the required planar shape of the contact area (95.0±2.44%) to obtain its desired localization (90.0±3.35%), to form the functional configuration of interdental embrasures (86.7±3.79%) with a high degree of probability. There was a significant (p˂0.05) difference in indicators characterising the quality of positioning and restoration of the contact areas of the posterior teeth when using the tested technique in comparison with the traditional technique of restoration of teeth with carious defects of class 2 according to Black. The effectiveness of the tested method of direct restoration of the contact surfaces of the posterior teeth while taking into account age characteristics has been proved. The efficiency and ergonomics of the contact-former developed by us for this technique have been confirmed. It is concluded that it is advisable to study the effectiveness of the proposed technique in a clinical setting.

ОЦЕНКА КАЧЕСТВА КОМПОЗИТНОЙ РЕСТАВРАЦИИ В ЗАВИСИМОСТИ ОТ АБРАЗИВНОСТИ ПОЛИРОВОЧНЫХ ПАСТ

Introduction. Psychological comfort is one of the most important components in the formation of a healthy, full-fledged personality. The requirements of patients to the dentist are not only not limited to the treatment of the underlying disease and the successful restoration of lost functions, but also include the achievement of a good aesthetic effect — patients highly appreciate a beautiful, relief and at the same time smooth restoration. Thus, the relevance of dental restoration is acquiring not only medical significance, but also social connotation. The aim of the work was to carry out a comparative assessment of the quality of the composite restoration using polishing pastes of various abrasiveness. Material and methods. The study involved 60 patients of both sexes, aged 18-43 years, who underwent aesthetic restoration in the area of the anterior group of teeth of 4 and 5 classes according to Black's classification using the light-curing composite material Enamel plus HRi UD5. The observation was carried out in the immediate and long-term periods (12 months after the end of treatment). For finishing the restorations, we used Cleanic, Flairesse, Clean Polish and Enamel Shinec polishing pastes with different RDA indices. The patients were divided into 4 groups depending on the polishing paste used. Results and its discussion. As a result of the study, it was revealed that the RDA index of polishing pastes plays an important role in finishing, exerting great importance on the smoothness of the restoration, "dry shine" and allows to achieve better marginal adaptation of the material and better color fastness of the restoration. Conclusions. Thus, our study revealed the best result in the paste with the maximum value of RDA (83) — Flaresse (DMG).

A Comparative Clinical Study of the Self-Adhering Flowable Composite Resin Vertise Flow and the Traditional Flowable Composite Resin Premise Flowable

Background. The aim of this research was to carry out a comparative clinical study of a self-adhesive, light-curing composite material called Vertise Flow and a traditional flow material called Premise flowable used in combination with dedicated bonding systems. In order to standardize the clinical environment, the stability of oral hygiene (analyzed with the oral hygiene index and the approximal plaque index) was taken into consideration. Methods. The study involved 37 patients with 64 fillings. They were distributed into three groups: 22 fillings in Group I, 22 fillings in Group II and 20 fillings in Group III. In Group I (G I), Vertise Flow material was applied without the use of an etching agent or a bonding system; in Group II (G II), Premise flowable material was applied without the use of an etching agent, but with the use of the OptiBond All-In-One seventh-generation bonding system; in Group III (G III), Premise flowable material was applied after etching and treatment of the hard tooth tissues using a fifth-generation OptiBond Solo Plus bonding system. Then, at appropriate time intervals (0, i.e., right after filling and after 6, 12 and 24 months), the fillings were subjected to clinical evaluation, conducted according to the Ryge scale criteria with the use of registration by means of a fluorescent high-intensity visible light beam produced by a camera (Vista Proof). Results. The quality of fillings performed with the use of comparable materials was subjected to clinical evaluation using the Ryge scale of fillings after 6, 12, and 24 months; the examination showed significant differences between the tested materials. The Vertise Flow material used without an etching agent or a bonding system (G I) presented the weakest results with respect to marginal adaptation and smoothness among those evaluated in this study. The intensification of the degradation continued over time until the final clinical observation at 24 months. The results confirmed that the best quality was achieved with the Premise flowable material after etching and treatment of the hard tooth tissues using a fifth-generation OptiBond Solo Plus bonding system (G III) relative to others for all time points during the observation. Conclusions. The used preparation scheme and bonding system have an impact on the final quality of the composite filling. There is a need to carry out a qualitative clinical evaluation of dental restorative materials under uniform conditions using evaluation scales.

Comparison of objective indicators of various properties of photocomposite materials with the subjective assessment of dentists

Relevance. Composite materials of light curing have a large number of indications for use and are actively used by dentists in clinical practice. The properties of these materials differ from their composition and the size of the filler. We conducted a survey of dentists of general practitioners of public and private dental clinics in Omsk to determine compliance, objective indicators of physico-chemical parameters of the studied composite materials and their subjective assessment by doctors using these materials in their work.Purpose. Comparison of objective indicators of various properties of photocomposite materials with the subjective assessment of dentists.Materials and methods. The study of the physicochemical properties of light-cured composite materials most commonly used in the practice of Omsk dentists in public and private clinics. A research design was developed and a survey of 148 dentists in Omsk was conducted to determine the subjective assessment of these materials.Results. A comparative analysis of the objective and subjective indicators of composite materials.Conclusions. The physicochemical parameters of the photocomposite materials are fully consistent with the subjective assessment of dentists in Omsk.

Determination of biofilm forming activity of microorganisms on synthetic polymeric materials.

Microorganisms are able to form biofilms on surfaces of biotic and abiotic nature. In turn, in human biotopes there are optimal conditions for the implementation of biofilm-forming activity. Moreover, in medical practice, polymeric materials are often used for drainage or prosthetics, which can also be successfully colonized by bacteria. However, in laboratory practice, the formation of biofilms is usually evaluated on glass or polystyrene. The purpose of the study is to evaluate the methodological features of studying the biofilm-forming activity of microorganisms on the surface of synthetic polymeric materials. We used strains of Staphylococcus aureus ATCC 25923, Escherichia coli K-12, Candida albicans ATCC 10231, as well as synthetic polymeric materials - DentLight Flow light-curing composite material (nano-hybrid fluid composite; Russia), glass ionomer chemical curing Fuji 1 (Japan), cement for temporary fixation of orthopedic constructions TempBond NE (USA), acrylic, polyurethane and polyvinyl chloride. The formation of biofilms in flat-bottomed ELISA plates in this study was considered as a control group. If the polymer belonged to cold curing materials, sterile flat-bottomed tablets were used, the bottom of which was filled with a thin layer of plastic. After hardening of the plastic, biofilms were formed in the tablets. In the second series of experiments, hot cured materials cut into equal parts 5×5×1 mm in size were placed in the wells of a plate and again used to determine biofilm formation with subsequent coloring. To extract the dye, the pieces were transferred to a new plate to exclude the amount of film biomass formed on the walls of the plate wells. In both cases, cultivation was carried out at 37° C for 24-48 hours. The biomass of the film was stained with fuchsin. Statistical data processing was performed using t-Student criterion. For the threshold level of significance, the value p <0.05 was taken. It is established that the proposed options for determining biofilm forming ability are available and indicative. It was revealed that the same microorganisms have individual biofilm formation indicators for each polymer material. The light curing dental composite and polyvinyl chloride exhibit the more pronounced antiadhesive properties than cements and polyurethane. Up to date, most of the studies of biofilm formation have been carried out using glass or polystyrene, which, as a rule, are not used for the manufacture of prostheses, catheters, drains, etc., which makes it difficult to assess the true film-forming activity of microorganisms. The proposed methodological approaches, especially the second option for preparing testing samples, solve this problem. In general, the proposed approaches to testing biofilm-forming activity on polymers are very simple to implement and generally available. For an adequate study of the biofilms formation, it will be advisable to use polymer materials, directly used in medicine, rather than polystyrene tablets, the material of which is found exclusively in laboratory practice.

LABORATORY STUDY OF STRENGTH CHARACTERISTICS GLASS-FIBER REINFORCED LIGHT-CURED COMPOSITE

Abstract. Resin-bonded bridges (RBB), which are made by the direct method are widely used to restore the integrity of the dentition. There is no common opinion regarding the optimal design of the retention elements of such prosthetics.&#x0D; Purpose is to study the influence of the design RBB supporting elements on the mechanical strength of fixing light-cured composite material, reinforced with glass-fiber tape and bulk, to the hard tissues of the teeth in laboratory conditions,.&#x0D; Materials and methods. The study was conducted on 20 laboratory samples. Extracted intact lower third molars were sprayed into halves in a transverse direction on two fragments. Each of the fragments was fixed in fast-hardening plastic so that the contact surface of the fragment of the removed tooth stood 2 mm above the plastic level, with the surface of the enamel, which was a circle, with a diameter of 4-5 mm, and was free. Samples were divided into 2 groups of 10 in each. In samples of group I, the preparation of an approximate surface of a tooth fragment was made in the form of a box-shaped cavity with rounded corners and a minimal conicality of vertical walls with the following parameters: length - 3 mm, width - 3 mm, depth - 2 mm. Reference cavities in the samples of the second group were prepared according to the proposed method, after preparation of the classical box-shaped cavity with parameters: length - 3 mm, width - 3 mm, depth - 2 mm, created additional retention elements in the form of dives located in the lower third each of the vertical walls of the cavities using special marking burs with height and thickness of the working part by 1 mm.&#x0D; In order to determine the strength of the light-cured composite fixation, reinforced by glass-fiber tape and bulk, developed device for investigating the maximum destructive loading of the samples by the shear method was used. The destructive load was measured using a dynamometer installed in the test vehicle to within 0.1 N. In addition, the specific strength of the samples was determined as the ratio of the destructive load to the surface area of the fracture or separation, and the safety margin, as the ratio of the destructive load to the mean the value of the chewing load in the area of molars taken for 150 N.&#x0D; Results and discussion. During conducting ofd the laboratory study of fixation strength of light-cured composite, reinforced by glass-fiber tape and bulk, to solid teeth tissues with different design retention elements there were found that the maximum destructive load and specific strength of the different sample groups were significantly different (p &lt;0,01). Indicators of destructive loading of samples of the 1st group were ranged from 576.5 N to 835.9 N and amounted to an average of 771.8+90.1 N. At the same time, the destructive loading for samples of the II group was from 2425.0 N to 2999.0 N with an average of 2805.9+191.4 N. Thus, the samples of the second group had almost 4 times the magnitude of the maximum destructive load than the values of group І samples.&#x0D; The indexes of the specific strength of light-cured composite fixing to the hard tissues of the supporting teeth were also higher in the samples of the second group, their values were ​​ranged from 341.1 N / mm2 to 421.8 N / mm2 with an average value of 394.5+26.8 N/mm2. In samples from Group I, these figures were ranged from 23.1 N/mm2 to 33.4 N/mm2 and amounted to 28.6+3.3 N/mm2 on average, they were 14 times smaller than II group indicators.&#x0D; Conclusion. As a result of the laboratory study, it was found that samples of the second group with the proposed design of retention elements had higher characteristics of the strength of fixation to the hard teeth tissues than those of group I with the "classic" box-shaped form of retention cavities. Destruction of samples of the second group occurred at a significant load that greatly exceeded that which occured in clinical conditions and at a distance from the retention elements, created according to the proposed design, due to insufficient physical and mechanical parameters of the light-cured composite and reinforcing fiberglass elements. The use of the proposed preparation option will reduce the risk of failure of the fixation and improve the prognosis for the long-term exploitation of resin-bonded bridges made by direct method.

Comparison of different final irrigant agitation techniques for the removal of Enterococcus faecalis biofilms from root canals: an in vitro study

Objective: The aim of this in vitro study was to compare the effectiveness of different final irrigant agitation techniques in the removal of Enterococcus faecalis biofilms from root canals. Material and Methods: In total, the root canals of 85 extracted single-rooted human maxillary incisors teeth were prepared using the Revo-S system to a 40/06 size. The apical foramen of each tooth was sealed by light-cured resin composite material to obstruct bacterial leakage. The specimens were sterilized in an autoclave at 121°C for 15 min and stored until further use. All teeth except five (negative control group) were inoculated with Enterococcus faecalis and incubated in a CO2 chamber at 37°C for 7 days; the trypticase soy broth was changed every 2 days. For the determination of possible biofilm formation, five of the 80 teeth were randomly selected as a positive control group; one tooth of positive control group was analysed for biofilm development by scanning electron microscope (SEM) and these teeth received no final irrigant agitation procedure. Then, the remaining 75 teeth were randomly divided into five test groups (n=15 each) and were sequentially irrigated with 5% sodium hypochlorite (NaOCl), 17% ethylenediaminetetraacetic acid and 5% NaOCl. Following each irrigant application, different final irrigant agitation techniques were introduced for 60 s (3×20-s sessions). Group 1 received manual–dynamic agitation, group 2 received passive ultrasonic agitation (PUI), group 3 received EndoActivator agitation, group 4 received photon-initiated photoacoustic streaming (PIPS) with the Er:YAG laser and group 5 received conventional syringe irrigation. Colony-forming units (CFUs) were counted in samples from the positive control and test groups. Data were analysed using Kruskal–Wallis and post-hoc Mann–Whitney U multiple comparison tests. Results: E. faecalis elimination was significantly better in the experimental groups than in the positive control groups (p &lt; 0.001). Manual–dynamic agitation and conventional syringe irrigation, with no significant differences between the two groups. Conclusion: Essentially, CFU reduction was significantly greater in the PUI, EndoActivator and PIPS groups than in the manual–dynamic agitation and conventional syringe irrigation groups (p &lt;0.001), with no significant differences among the former three groups.KeywordsEnterococcus faecalis; Irrigant agitation; Irrigant solutions; Photon-initiated photoacoustic streaming; Passive ultrasonic irrigation.

TRIBOLOGICAL TESTS OF THE NANOMATERIALS USED TO RECONSTRUCT MOLARS AND PREMOLARS WITH THE APPLICATION OF THE DIRECT METHOD

Physiological abrasion of teeth is a process of gradual loss of the hard tissue of opposite teeth resulting from age-related natural dental wear. In abrasion, the cusps and their slopes in the jaw and the mandible become flattened due to the mechanical load applied. The aim of this paper is to carry out a tribological and microstructural evaluation of modern composite materials used to reconstruct the teeth in the lateral part of the dental arch. Five light-cured composite materials were selected for tests. The tests involved the coefficient of friction and resistance to wear in a sliding contact in the presence of artificial saliva and the microstructure of the external surface of samples before the wear process and in the wear-related damaged area. The test method applied, which combines a biomechanical analysis of resistance to wear and the analysis of the microstructure before the wear process and in the wear-related damaged area, makes it possible to evaluate the tribological properties of composite materials used to reconstruct teeth in the lateral part of the dental arch.

Original Research. Surface Roughness Changes of Different Restoration Materials after Tooth Brushing Simulation Using Different Toothpastes

Abstract Background: The need for the whitening effects of toothpastes became primary for most users. Changes in the surface roughness of restoration materials after tooth brushing are inevitable, and the abrasion is known to increase the possibility of dental plaque accumulation. Aim of the study: To evaluate in vitro surface roughness changes of different dental restorative materials after tooth brushing simulation. Material and methods: Fifty specimens of two composite materials (Evicrol, Super-Cor), two glass ionomer materials (Glassfill, Kavitan Cem) and a silicate cement (Fritex) were prepared according to the manufacturer’s instructions. Each group of specimens was divided in three subgroups for tooth brushing simulation: using two different types of toothpaste and without toothpaste. Before and after 153 hours of tooth brushing simulation with a custom-made device, the surface roughness was measured with a surface roughness tester. Statistical analysis was performed after collecting the data. Results: All materials exhibited changes in surface roughness after the use of both toothpastes. The self-curing composite showed the less change and glass ionomer materials showed the greatest changes in surface roughness. Conclusions: The surface changes of dental materials depended on their composition and the cleaning procedure. Although self-curing composite was the most resistant to surface changes, its surface roughness values were high. Light-curing composite presented the lowest surface roughness values, even after brushing with toothpastes. The “medium” labeled toothbrush caused significant changes without toothpaste on the surface of light-curing composite, glass ionomer and silicate cement materials.

ATR technique, an appropriate method for determining the degree of conversion in dental giomers

Dental light-curing giomers were developed to combine the favourable properties of diacrylic resin composites (DRCs) and glass-ionomer cements (GICs) in a single material and to eliminate their inherent drawbacks. Giomers are characterized by their aesthetic appearance, high mechanical properties, adhesion to dental tissues as well as fluoride release and recharge abilities. The qualities of the giomers are greatly influenced by the level of conversion of the component resins. Infrared spectroscopy is one of the most largely used techniques for the determination of the degree of conversion in resin-based dental materials. However different results were obtained due to the performances of the used methods. The present work presents the determination of conversion degree in a series of dental copolymers and their corresponding giomers using transmission Fourier transform infrared spectroscopy (FTIR) and an attenuated total reflection technique (ATR) technique, respectively, the main aim being the study of the influence of the materials composition and of the light curing modes upon the achieved conversion in the cured giomers. Beautifil II commercial giomer was used as a control. A halogen lamp and a diode-blue LED lamp were used for the curing of the materials. The results showed that the composition of the resins greatly influenced the conversion. The highest conversions (up to 79%) were obtained in the case of the experimental giomers which contained the experimental Bis-GMA urethane analogue, followed by the Beautifil II giomer (61%) and experimental giomers based on commercial Bis-GMA (up to 50%), respectively. The resins light-cured by using the diode-blue LED lamp presented slightly higher conversions than the resins cured by halogen lamp. The study demonstrates the possibility to evaluate easily and reproducibly the conversion in light-curing composite materials with complex chemical composition and structure, particularly in the case of giomers by using the ATR technique.

Mechanical Properties of Calcium Fluoride-Based Composite Materials.

Aim of the study was to evaluate mechanical properties of light-curing composite materials modified with the addition of calcium fluoride. The study used one experimental light-curing composite material (ECM) and one commercially available flowable light-curing composite material (FA) that were modified with 0.5–5.0 wt% anhydrous calcium fluoride. Morphology of the samples and uniformity of CaF2 distribution were analyzed using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). Mechanical properties were tested after 24-hour storage of specimens in dry or wet conditions. Stored dry ECM enriched with 0.5–1.0 wt% CaF2 showed higher tensile strength values, while water storage of all modified ECM specimens decreased their tensile strength. The highest Vickers hardness tested after dry storage was observed for 2.5 wt% CaF2 content in ECM. The addition of 2.0–5.0 wt% CaF2 to FA caused significant decrease in tensile strength after dry storage and overall tensile strength decrease of modified FA specimens after water storage. The content of 2.0 wt% CaF2 in FA resulted in the highest Vickers hardness tested after wet storage. Commercially available composite material (FA), unmodified with fluoride addition, demonstrated overall significantly higher mechanical properties.

Antibacterial Properties of Calcium Fluoride-Based Composite Materials: In Vitro Study.

The aim of the study was to evaluate antibacterial activity of composite materials modified with calcium fluoride against cariogenic bacteria S. mutans and L. acidophilus. One commercially available conventional light-curing composite material containing fluoride ions (F2) and two commercially available flowable light-curing composite materials (Flow Art and X-Flow) modified with 1.5, 2.5, and 5.0 wt% anhydrous calcium fluoride addition were used in the study. Composite material samples were incubated in 0.95% NaCl at 35°C for 3 days; then dilution series of S. mutans and L. acidophilus strains were made from the eluates. Bacteria dilutions were cultivated on media afterwards. Colony-forming unit per 1 mL of solution (CFU/mL) was calculated. Composite materials modified with calcium fluoride highly reduced (p < 0.001) bacteria growth compared to commercially available composite materials containing fluoride compounds. The greatest reduction in bacteria growth was observed for composite materials modified with 1.5% wt. CaF2. All three tested composite materials showed statistically greater antibacterial activity against L. acidophilus than against S. mutans.