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Search Results: 1 - 10 of 3572 matches for " Tiha?ek-?oji? Ljiljana "
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Extent of diffusion of organic molecules in the enamel tissue of dogs
Tihaek-?ojiLjiljana
Acta Veterinaria , 2005, DOI: 10.2298/avb0501053t
Abstract: The objective of this study was to evaluate the extent of diffusion of organic molecules in the enamel tissue, of permanent teeth. The experimental study was performed in vivo on dogs. To the experimental dogs the molars on the right side of the lower jaw underwent enamel tissue reduction without additionally placing any tooth protection. Teeth on the left side of the lower jaw were left intact thus representing the control. After 12 months animals were sacrificed, experimental and control teeth extracted and the study of diffusion in vitro carried on. For that purpose an organic spin marker 4-amino - 2,2,6,6,-tetramethyl-piperdinyl 1-oxi (4-Amino-Tempo) was selected. The property of this marker is that it contains a nitroxide radical which is stable in a neutral and base environment, and due to the unbound spin of the free radical it is highly suitable for the electronic paramagnetic resonance method (EPR). Studies on the diffusion of organic spin markers in the enamel tissue are performed by submerging the prepared tooth in a water solution containing the marker substance. From the intensity of the EPR spectrum filmed after tooth withdrawal from the water solution, distribution diffusion time and penetration depth of marker molecules were established. Coefficients of organic spin marker diffusion and saturation concentrations of marker molecules in the enamel were determined. The observed variations in the area! and time for distribution of diffused molecules were explained by the binding possibility of the NO-radical from the marker molecule to the enamel tissue. The results of the experiment contained in this work contribute to a better understanding of the spin marker organic molecule movement through the enamel tissue which is controlled by the mechanism of diffusion and chemical bonding of the marker molecule to the enamel structure. The results of the experimental research also indicate the harmful effects of leaving the enamel tissue without protection.
Possibilities of binding organic molecules within the enamel crystal structure in dogs
Tihaek-?ojiLjiljana
Acta Veterinaria , 2005, DOI: 10.2298/avb0503227t
Abstract: The main objective of this paper is to determine the possibilities of binding organic molecules to the enamel crystal structure. The experimental study in vivo was performed on maxillar molars in dogs. Time in vivo was 12 months after which animals were executed. All intact teeth were extracted and the study of the enamel crystal structure was continued in vitro. After treating the enamel tissue with the solution of organic spin marker 4-Amino-Tempo, the follow-up of the changes of values of the apatite crystal unit cell parameters was done by X-ray diffraction. The following conclusions may be reached after evaluation of the obtained results: in addition to the process of diffusion through the interprysmatic space of the enamel tissue, the organic molecules also play a crucial role in the changes of the crystal grid size, due to binding of organic parts of molecules in the enamel crystal structure. Permanent oscillations of the existing oxygen bonds in the enamel crystal structure have been determined every few weeks and depend on the process of substitution and resubstitution of OH ions by ions from organic and inorganic molecules and various dental materials. The local application of the fluorine based preparations on permanent teeth must be repeated every two months due to breakedown of oxygen bond and resubstitution.
Justification of forming active prosthetic segments
Tihaek-?ojiLjiljana,?auli? Slobodan
Stomatolo?ki Glasnik Srbije , 2004, DOI: 10.2298/sgs0403153t
Abstract: The aim of this paper was to examine the justification of forming active prosthetic segments on the abutment teeth for the incline of the elements of removable partial denture. Methods. The investigation was performed during 3-years observational period, at the Prosthodontic Clinics of Belgrade University Dental School, and the Military Medical Academy (MMA). During the mentioned observation period two groups of 200 patients with different kinds of edentulousness were analyzed, indicated for the design of metal frame removable partial dentures (MFRPD) with cast clasps. A total of 400 patients represented 50% of the sample chosen by random choice method for the determined observational period and dental institutions. Results. The evaluation of justification of the abutment teeth preparation was done during the analysis of the requirement of forming: guide planes, planes for occlusal rests, vestibular under cut, oral under cut. Conclusion. Upon the evaluation of the performed analyses the following can be concluded: during the composition of every MFRPD it is necessary to use at least two or more guide planes, depending on the type edentulousness of patients' teeth; formation of guide planes is performed in excessively high number of the abutment teeth (over 95%); during the composition of each particular MFRDP it is necessary to use as more occlusal rests as possible, at least 3, or more, which also depends on the type of patients' edentulousness; composition of the planes for occlusal rest has to be performed in almost all the patients (over 95% of the abutment teeth); vestibular planes of the abutment teeth should be prepared in over 50% of the used teeth; oral planes are prepared within the preparation of the abutment teeth for other active prosthetic segments. Conclusion. It is necessary to perform the composition of active prosthetic segments according to the plan established for the study models, both if the preparation of teeth for the adoption of MFRDP elements with clasps represents the use of an uninvasive, or an invasive dental method.
Dedicated composite fillings inlays
?auli? Slobodan,Tihaek-?ojiLjiljana
Vojnosanitetski Pregled , 2003, DOI: 10.2298/vsp0305569s
Abstract: Background. The aim of the study was to evaluate the quality and persistance of esthetics of dedicated inlay by clinical methods. Methods. The paper reviews the clinical significance and technique of preparing particular composite inlays before and after the construction of the metallic framework partial denture. On the basis of indications the total of 30 inlays were placed into cavities under relatively dry working conditions. Six, twelve eighteen and twenty-four months after the placement of filling, control check-up was carried out by Ryge criteria. Results. After two years marginal discoloration as well as the change of the colour occured in 3.3% of inlays. There was neither detectable secondary caries, nor the symtoms of pulpal damage. The requirements to be fulfilled concerning the composite materials in order that they can be implemented for this purpose, were also discussed. Conclusion. From the clinical point of view, purpouse inlays from Herculite XRV lab C8B in combination with Opti Bond System and composite cement Porcelite Dual Cure showed high functional and esthetic values in the observational period of two years.
Mesiodens and paramolar in the medieval age skeletal remains
Tihaek-?ojiLjiljana,??epanovi? Miodrag,?uri? Marija
Stomatolo?ki Glasnik Srbije , 2002, DOI: 10.2298/sgs0204086t
Abstract: Evolution as in all segments of human behavior and existence has left traces on human teeth. The aim of this study was to determine the frequency of the supernumerary teeth in skeletal remains found at the archeological site Stara Torina and SEM evaluation of the changes on the supernumerary teeth. The study included 90 skulls and 81 jaws of both sexes with average age 20-60 years. Supernumerary teeth were prepared for SEM for analyzing dental tissues. Six supernumerary teeth were found, among them five mesiodensand one paramolar. The frequency of hyperdontia in these skeletal remains is 2,1%. Mesiodens is different morphologically from the incisor it replaced and took part in occlusal contacts during mastication. Paramolar is different morphologically from molar teeth and it did not take part in occlusal contacts during mastication because of its low adherence for bone tissues and small dimensions.
Determination of the dog teeth color
Tihaek-?ojiLjiljana,Stan?i? I.,Jelenkovi? Aleksandra
Acta Veterinaria , 2008, DOI: 10.2298/avb0806573t
Abstract: Tooth color depends on hard tooth tissue structures, above all dentine, and is genetically determinated. Nutritive habits and nutrition patterns during the lifetime can influence the change of crystal structure of enamel and dentine and consequently tooth color. The purpose of this research is to determine the color of dog teeth and to compare it to human tooth color. Standardized color key was used, thus overcoming all three color parameters: main color - hue, satiate - chroma and brightness - value. The obtained results show that both colors of dog and human teeth belong to the same spectrum. Dog teeth more frequently have a darker color which can be connected to the fact that their teeth are more worn and consequently a more intensive diffusion process is undergoing due to the changes in crystal structure because of the newly formed bondings of organic molecules into the crystal structure of the enamel.
Anatomically based 3D geometric modeling of specific biological structures
Tihaek-?ojiLjiljana,Mili? Aleksandra,?ivkovi? R.,Ili? J.
Acta Veterinaria , 2007, DOI: 10.2298/avb0704381t
Abstract: Mechanical behavior of biological structures is a common subject of scientific research. The results of such investigations offer the precise insight into the biomechanical properties of biological structures and are usefull for predicting their behavior when subjected to loading. Although, such biomechanical investigations were conducted on experimental animals nowadays are very popular investigations concerning mathematical experimental models. The most common is the finite element method analysis. A digital model of a structure of interest has to be created for an investigation with the finite element method. Once the digital model is created with the use of computer technology numerous changes of elements and structures are possible, with different applications of the simulated load. The aim of this paper was to to present the development of our own three-dimensional tooth model created for finite element analyses of intact tooth behavior under functional loading. Also, the idea was to evaluate the possibility for using finite element analysis in veterinary biomechanical research. Our own 3D model was created using computer software according to available literature data, and facts gained from freshly extracted intact teeth and plaster models. It is necessary to emphasize that FEM is an effective tool that has been adapted from the engineering arena to biomechanic research and has the potential to contribute to the growing scientific basis of knowledge in veterinary dentistry.
Optical metrology analysis of the lower jaw deformations
Tanasi? Ivan,Tihaek-?ojiLjiljana,Mili?-Lemi? Aleksandra
Vojnosanitetski Pregled , 2011, DOI: 10.2298/vsp1104336t
Abstract: Background/Aim. New optical stereometric methods based on both contact and noncontact mechanisms for displacement measurement have become common methods in biomechanical behavior research of biomaterials, bone and soft tissue. The aim of this study was to register and measure possible deformations of the lower jaw (mandible) with the intact dental arch using optical metrology method. Methods. The system for full field measurement of deformations (strains) comprised of two digital cameras for a synchronized stereoview of the specimen, and the Aramis software. Results. The maximum mandibular bone strains were measured in the regions of the lower first premolar and the lower second molar. In the action force of 500 N simulated in the region of the first lower premolar the intensity of deformation was 86 μm. The value of maximum strain in the bone around the molars was 24 μm for the force of 500 N acting on the second lower molar. When it comes to premolars, 3-5 times stronger deformation was observed in the region of the first lower premolar, compared to the deformation values of the second lower premolar area. Conclusion. Under loading of the applied forces the measured strains were in the elastic deformation area, meanning that the dependence of force and deformity is linear. The highest values of strain measurements obtained by the optical method were found in the jaw bone tissue around the loading teeth, and the bony regions of the triangle and mental region. According to the obtained results from the Aramis processing software it can be concluded that this method is applicable in a variety of biomedical research.
Adaptation of Oral Health Impact Profile (OHIP-14) index for measuring impact of oral health on quality of life in elderly to Serbian language
Stan?i? Ivica,Tihaek-?ojiLjiljana,Jelenkovi? Aleksandra
Vojnosanitetski Pregled , 2009, DOI: 10.2298/vsp0907511s
Abstract: Background/Aim. There is an evidence of increasing necessity to use indices for measuring impact of oral health on the elderly life quality for the purposes of the state-of-the art clinical dental practice. It is at least because data obtained in that way suggest whether a treatment is required, help in deciding upon a kind of dental treatment, as well as in evaluating the extent of success of the applied therapeutical procedures. The aim of the study was to translate into Serbian the Oral Health Impact Profile-14 (OHIP-14) index and to assess its validity in practice as its initial verification in the Serbian speaking areas. Methods. The OHIP-14 index was translated into Serbian and check-up of its easy-to-understand done in a group of 30 common elderly (above 65 years of age) with a total or partial prosthetic restoration. The study individuals did not fill in a questionnaire by themselves, instead the questions were put orally. If needed, additional explanations were given with no any suggesting a possible answer. Results. Considering the given answers and the shown need for additional explanations to some questions indicated that the question number 5 in the OHIP-14, namely 'Have you been selfconscious because of your mouth or dentures?' (Serbian, 'Da li ste bili samosvesni usled problema sa Va im ustima i protezama?') cannot be adequately translated into Serbian because even 28 (93.3%) of the tested individuals were not able to understand it inspite the given explanations. Other questions were well understood, thus allowing to use the answers to them as score for a certain discomfort. Of all the tested, 13 (43%) denied any psychosocial disorders or experienced them only rarely, while 60% of the tested answered affirmately to the question 'Do you consider your life generally less satisfactory due to the problems induced by teeth and dentures?' pointing out a significant impact of oral health condition on the quality of life. Conclusion. The OHIP-14 index renders valuable and dependable data on the quality of life of elderly with dentures, thus it is favorable to use it in practice. Due to difficulties in understanding the question number 5, however, it was omitted off the final Serbian language version. Anyhow, its validity in a more numerous test group should be evaluated, as well as other indices introduced into Serbian speaking area to let a comparison made and the most suitable questionnaire used.
The possibilities of prosthetic rehabilitation of shortened dental arches in elderly patients
Tihaek-?ojiLjiljana,Stan?i? Ivica,Jelenkovi? Aleksandra,Mili?-Lemi? Aleksandra
Stomatolo?ki Glasnik Srbije , 2008, DOI: 10.2298/sgs0804238t
Abstract: Introduction. Functional consequences of posterior tooth loss are multiple; late and inadequate rehabilitation lead to further collapse of stomatognathic system, which is especially distinct in elderly population. Aim of this paper is to present advantages and disadvantages of different modalities of prosthetic treatment of shortened dental arch in elderly patients. Treatment with overdentures are convenient in this population because it is non-invasive and reversible. Periodontal problems and root caries are main complications of this treatment, but denture relaying after extraction and easy conversion into complete dentures facilitate resolving this complications. Removable partial dentures are one of the mostly indicated treatments for shortened dental arch. They improve masticatory efficiency, but disadvantages are in inferior aesthetic characteristics and comfort. Mechanical failures can be avoid by detailed analyze and correct planning. Treatment of shortened dental arch with fixed partial denture with distal extension can be very convenient solution for elderly patient. Osseointegration process and implant treatment promises every day more in prosthetic rehabilitation of elderly. Relayed prosthetic rehabilitation is recommended, not because of longer process of ossteointegration, but because of delayed recovery of soft tissues and general health condition of elderly. Conclusion. Each of before mentioned therapy modalities have its advantages and disadvantages in meaning of technical procedure, duration in function, possible complications and patient's comfort and satisfaction. In elderly patients, possible complications are more complex; therefore treatment must be done quickly, efficiently, and having in mind patient's general and oral health condition, level of cooperation and economic status.
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