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Introduction: Diseases of the pulp and periapical tissue, which require endodontic treatment, are often accompanied by a large tooth crown defect caused by caries. Regardless of well-performed endodontic treatment, endodontically treated teeth are prone to fractures. This raises the issue of tooth restoration after quality endodontic treatment. Crowns represent dental restorations, made of ceramics or metal-ceramics, which, in addition to establishing the morphology of the teeth, also have the function of protecting teeth with a larger crown defect. The aim was to review the factors that could lead to the fracture of endodontically treated teeth. Conclusion: When deciding whether to restore an endodontically treated tooth with crowns, it is necessary to consider several factors, among which are the loss of hard tooth tissue, the structure of the endodontically treated teeth, the forces to which the teeth are exposed in the oral cavity, the instruments and materials used during the endodontic treatment, as well as the aesthetics of the endodontic treated teethProsthetic reconstruction with a crown proved to be significant in the protection of posterior endodontically treated teeth, while treatment of the front teeth with crowns is indicated for the teeth with major damage and aesthetic defects that cannot be repaired by other conservative procedures.

Information about oral health available on the Internet, videos of dental procedures on YouTube, and Facebook groups, whose members are dentists, have contributed to dentistry finding its place online. Aim: The aim of the study was to investigate the attitudes and behavior of student population towards: dental marketing on Instagram, patient-dentist relationship through social media, and information about oral health found on the Internet. Participants and Methods: The research included 226 students of the University of Niš, who participated in an anonymous online survey of 16 questions created in Google Forms. Results: Every sixth respondent from those who follow a dental office on Instagram have chosen the office because of Instagram. Females search for dentists more frequently on the Internet than males. Most of the respondents, who are friends with dentist on a social network, still most often contact them by phone. The oldest respondents do not find it appropriate to be friends with a dentist on social media. The majority of those who are unsure about the accuracy of oral health informations from the Internet, do not discuss them with their dentist. Conclusion: Instagram does not play a key role in the choice of a dentist among respondents, and communication with a dentist through social media is less prevalent than other forms of communication with a dentist. However, more than half of the respondents consult the Internet before going to the dentist.

Musculoskeletal disorders (MSD) are characterized by discomfort, occasional or permanent pain in the joints, muscles, tendons and other soft tissues caused by the repetition of certain body movements or uncomfortable and forced body posture. Dentistry is considered a high-risk profession for the development of these disorders. The aim of the research was to investigate the occurrence of MSD in the population of dental students of the Faculty of Medicine, University of Niš, Serbia. Total of 170 dental students participated in the research. In order to examine the emergence and distribution of MSD, students filled out a modified Nordic questionnaire. The results showed that 70.6% of students suffer from MSD. MSD were almost equally represented in both genders (69.7% in male and 71.1% in female). The most common localization of pain was in the area of the upper back in 32.3% of cases. A total of 54.1% of students declared that the pain intensity was moderate and that in 41.2% of cases it lasted as long as the work with the patient. In 49.4% of cases, the pain does not affect practical work, and as a relief measure in 53.3% of cases, students use rest. MSD appear already in the first years of studies and tend to intensify with the length of studies. Given that musculoskeletal pain occurs already in the early period of student practice, it is necessary to study ergonomic factors that are of great importance for the occurrence and intensification of these disorders.

Introduction Maxillary premolars often undergo endodontic treatment, which requires detailed knowledge of their canal morphology. The aim of this study was to determine the most common number of roots of maxillary premolars by analyzing CBCT images, as well as to determine the most common root canal configuration in maxillary premolars in the population of Southeast Serbia using the new system for classifying root canal morphology by Ahmed et al. Material and methods 55 CBCT images of male and 63 CBCT images of female patients were analyzed, which included 223 maxillary first premolars and 207 maxillary second premolars. The analysis was performed in the program Galileos. The number of roots of these teeth was determined and the canal morphology was classified in relation to the gender and side of maxilla. Results The maxillary first premolars most often had two roots and configuration type 2 TNB1 P1 , while the most maxillary second premolars had one root and configuration type 1 TNB1 . No significant difference was observed in the number of roots and type of configuration between male and female, as well as between left and right sides. Conclusion The classification of the tooth canal system according to Ahmed et al. emphasizes the advantage of simultaneous classification of the number of roots and the number of canals. Although most premolars do not pose a problem for treatment, there have been registered canal configurations of maxillary premolars that can be a challenge for endodontic treatment. A detailed analysis of the canal configuration can be performed using CBCT.

Introduction Sudden fracture of instruments without previous warning signs, which occurs due to cyclic and torsional fatigue, represents the biggest problem and one of the most difficult complications during endodontic therapy. The aim of this research was to check the influence of diameter of the instruments on the appearance of cyclic fatigue in simulated canals in full rotation. Material and Method The study analyzed 24 ProTaper Universal instruments (12 instruments with a diameter of 25 and 12 instruments with a diameter of 30) and 24 ProTaper Next instruments (12 instruments with a diameter of 25 and 12 instruments with a diameter of 30). The instruments were tested in an artificial canal stuffed in a metal block at an angle of 45° and a corner radius of 5 mm. The operating time of each instrument until fracture was measured, and then the number of cycles to fracture (NCF) was calculated. The length of the fractured fragments (FL) was measured with a Vernier caliper. Results The number of cycles to fracture was higher (p < 0.001) in instruments of the ProTaper Universal group of diameter 25 (367.83 ± 17.00) compared to instruments of diameter 30 (329.33 ± 12.86) of the same group. The number of cycles leading to the fracture in instruments of the ProTaper Next group of diameter 25 (1189.33 ± 18.97) was higher (p < 0.001) compared to instruments of the same group of diameter 30 (971.08 ± 15.26). Conclusion Obtained results indicated that with an increase in the diameter of rotating endodontic instruments, there is a decrease in the resistance to cyclic fatigue.

Introduction In addition to the advantages of glass ionomer cements that have led to their wide application, hybrid glass ionomer cements have been developed to overcome the shortcomings in mechanical resistance. The aim of the study was to perform an ultrastructural analysis of restorations made from conventional and hybrid glass ionomer cements after recommended finishing procedures and application of a protective coating. Materials and Methods This study analyzed 30 samples of conventional glass ionomer cement Fuji IX™ and 30 samples of hybrid glass ionomer cement EQUIA Forte HT Fil™. The samples were prepared in cylindrical molds and divided into the three groups. The first group of samples, after adaptation, was left untreated and served as a control group. The second group consisted of samples that were finished with a cylindrical diamond bur with water cooling. The samples in the third group were finished and protected with appropriate coatings (G-COAT PLUS™ and EQUIA Forte Coat™). The samples were analyzed using scanning electron microscopy. Results The finishing procedures of Fuji IX™ samples significantly reduced crack width (t = 3.42, p < 0.005; Z = 3.25, p = 0.001). Similarly, the crack width in EQUIA Forte HT Fil™ samples was also significantly smaller in treated samples (t = 4.78, p < 0.001; Z = 4.28, p < 0.001). Ultrastructural analysis of both materials showed the complete absence of cracks in finished samples protected by coatings. Conclusion Finishing of conventional and hybrid glass ionomer cements results in a reduction in the number of cracks as well as a decrease in their widths, and the protective coatings completely cover remaining cracks.

Introduction Endodontic instruments during root canal treatment come into contact with dentinal debris, irrigation solutions and medication agents, which reminants should be eliminated before sterilization. The aim of the study was to verify the effectiveness of different cleaning methods for removing calcium hydroxide paste residues from the surfaces of the working parts of hand instruments, as well as to propose an effective protocol for cleaning endodontic instruments before sterilization. Material and methods Forty-two new hand endodontic instruments were used to remove calcium hydroxide paste from the filled canals of extracted teeth. After contamination with medication, they were divided into the four groups and subjected to individual decontamination methods - mechanical, chemical and ultrasonic, as well as a combined protocol. The instruments were then observed under a light microscope. The effectiveness of the methods was evaluated based on the amount of residual matter on the surface of the working parts of the instruments. Results The combined protocol showed a statistically significant difference in the achieved level of cleanliness compared to mechanical (ch2 = 12.00 p < 0.05) and chemical methods (ch2 = 12.00 p < 0.05), but there was no statistically significant difference compared to ultrasonic cleaning in disinfectant solution (ch2 = 2.4 p > 0.05). By applying combined protocol, instruments with completely clean surfaces were found, as well as the lowest values of contamination at the level of the entire group of instruments (8.33%). Conclusion The protocol that consisted of mechanical cleaning with a sponge soaked in chlorhexidine gluconate, chemical soaking in sodium hypochlorite, and ultrasonic cleaning in a disinfectant showed the best efficiency in removing calcium hydroxide residues.

Introduction Root canal preparation is one of the most important active phases in the treatment of infected and noninfected teeth. Nickel-titanium (NiTi) instruments are increasingly used in endodontic therapy due to their superior properties compared to those made of stainless steel. The aim of this research was to perform an analysis and comparison of cyclic fatigue in ProTaper Universal and ProTaper Next rotary NiTi instruments in full rotation in simulated canals. Material and methods Twelve ProTaper Next and twelve ProTaper Universal instruments were analyzed in the study. The instruments were tested in an artificial canal stuffed in a metal block at an angle of 45° and a corner radius of 5 mm. The operating time of each instrument until fracture was measured and the number of cycles to fracture (NCF) calculated. Results ProTaper Next instruments showed greater resistance to cyclic fatigue compared to ProTaper Universal. The NCF value was significantly higher in ProTaper Next (1,296.83±20.2) instruments (p

Introduction It is known that patients primarily come to general practitioners asking for help with oral disease. Although the matter falls out of the frame of `traditional`medical practice, ethical guidance suggests that doctors should examine one`s oral cavity with the aim of recognizing symptoms which treatment could improve the quality of oral and general health leading to an early discovery of potentially severe diseases. The aim was to examine the habits and attitudes of medical students and graduates who are interns related to oral health care, their knowledge of oral cavity diseases and systematic diseases with symptoms manifested in oral cavity, as well as their knowledge of patients who are at risk from dental interventions. Material and methods the survey was conducted on the sample of 100 subjects. The questionnaire consisted of 16 questions. The results were collected and statistically analyzed. Results the majority of subjects go to the dentist only after the toothache starts. Although 84% of medical students make sure to check oral cavity while taking medical history, more than half of the examined medical students would not send the patient to dentist for consultation. Every tenth student was not able to state other local disease of oral cavity apart from tooth decay. Even 6% of examined students classified the tooth decay as an aesthetic problem. Half of examined students considered their study program needed course in the field of dentistry. Conclusion Medical students are not well informed about the field of oral hygiene and pathology of oral cavity. Interdisciplinary cooperation of General Practitioners and Dentists is important.

Rickets is a disorder of bone mineralization in children's skeleton. It is most often associated with vitamin D deficiency, however, it can also occur due to a decrease in serum phosphate levels, which leads to inadequate tissue mineralization, with consequent skeletal deformity and growth disorders. Patients with hypophosphatemic rickets show teeth changes at the morphological and histological level, as well as on radiological images. The aim of this study was to perform clinical and radiological evaluation of dental manifestations of hypophosphatemic rickets in a four-year-old boy, as well as to point out the necessity of including a dentist in the treatment of this disease in order to prevent oral complications.

Physiological aging process leads to changes in all tissues and organs of the human organism. Changes of the tooth color with age occur as a result of the pulp chamber reduction and deposition of secondary dentine, when dentine become thicker and less transparent. The aim of this study was to determine degree of the tooth color change in relation to the age of patients and the gender. The study included 166 patients, aged from 18 to 77 years. All patients were divided into four age groups. Determination of the tooth color was performed by visual method using the Philips zoom shade guide chart in the middle third of the healthy upper central incisors. The results showed that 21,7% of the patients between 18-30 years had dominant light tooth color, 12.9% of the patients from 31-45 years had the medium color, and patients from 46-60 and older than 61 years in most cases had dark color of the teeth (9.1% and 21% respectively). The dominant light tooth color was A2, medium color A3, while the most common dark color was A3.5. Women had significantly lighter teeth compared to men. The study showed that younger patients had lighter teeth and that the color of teeth become darker with age.

Introduction Cytokine network plays an important role in pathogenesis of chronic periapical lesions. The aim of this study was to determine the concentration of interleukin-6 (IL-6) in tissue homogenates of human periapical lesions and correlate its levels with symptomatology and size of the lesions. Materials and Methods 93 samples of chronic periapical lesions were obtained after extraction of teeth. Samples were divided according to the clinical presentation as symptomatic and asymptomatic, and according to the size as large and small. The concentration of IL-6 was analyzed using ELISA. Results Statistically significant difference in IL-6 concentration was observed in symptomatic lesions compared to asymptomatic (p

Copyright of Acta Stomatologica Naissi is the property of Clinic of Stomatology Nis and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background. Beer, red and white wine are acidic drinks whose frequent consumption can increase the risk of dental erosion. Objectives. To establish the effect of beer, red and white wine on the morphology and surface roughness (SR) of human enamel using different exposure times in a cyclic de- and remineralization model in vitro. Materials and methods. The experiment included 33 surgically extracted impacted human third molars from patients aged 18-25 years. Enamel samples obtained by cutting crowns (n = 132) were submitted to alternate cycles of demineralization in (1) beer, (2) red wine, (3) white wine, (PC) positive control (orange juice), and remineralization in artificial saliva, which also represented a medium for negative control (NC). The experiment included cycles with different exposure times in alcoholic beverages and orange juice of 15, 30 and 60 min. Thus, 12 groups were formed (for each drink and each exposure time) containing 10 samples each, while the NC group consisted of 12 samples. Experiments were repeated 3x/day for 10 days. Enamel surface alterations were determined by stylus profilometry (average surface roughness (Ra)) and scanning electron microscopy (SEM). The Shapiro-Wilk test, independent samples Kruskal-Wallis test and multiple comparisons (all pairwise) were performed. Results. With increasing exposure time, there was a positive correlation with Ra for white wine- and orange juice-immersed samples (60 min compared to 15 min), which was also observed using SEM. There was no significant difference in the Ra between the other experimental samples for the same exposure time. Conclusions. This study confirms a certain erosive potential of beer, red and white wine, and a significant relationship with pH, titratable acidity (TA) and SR, but not with the exposure time for all tested alcoholic beverages. Moreover, differences among the ultrastructural patterns caused by alcoholic beverages over the enamel surface were observed. [ABSTRACT FROM AUTHOR]

Introduction/Objective. The success of endodontic treatment depends on the effective removal of root content, the elimination of infection, and the hermetical sealing of the root system using a compatible material. The objective of this paper was to evaluate the tissue response to the implant of endodontic material based on calcium hydroxide into the bone in the artificially prepared defect in a rat mandible. Methods. The research was carried out on 40 Wistar rats. The artificial defect was made between the midline and the mental foramen on the left side of the mandible. The prepared defect was left to heal spontaneously in animals of the control group, while among the animals of the experimental group the sealer Apexit (Ivoclar Vivadent, Schaan, Lichtenstein) was implanted into the experimental defect. The tissue samples consisting of the experimental field and the surrounding bone were microscopically analyzed with a light microscope. Results. During the initial phase, 15 days after the implantation, signs of chronic inflammation were noted and expansion of the Volkmann’s and Haversian canals. On the 30th day after the implantation, osteosynthetic activity and filling with newly-formed bone were noted. Changes were also noted in cement lines in the wider region of the experimental defect. Sixty days following the implantation, the bone was gradually remodeled. Ninety days after the implantation, a restitutio ad integrum was noted. Conclusion. Apexit does not lead to any disruptions in normal reparation processes nor in morphofunctional relations in bone tissue during the remodeling phase. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 175061: The antioxidant protection and potentials for differentiation and regeneration of mesenchymal stem cells from different tissues during the aging process]

The mental foramen is an important anatomic landmark not only in dentistry but also in forensics, and the knowledge about its accurate location is important in receiving local anesthesia, during surgical and endodontic procedures. The purpose of this study was to determine the most common position and shape of the mental foramen in the Southeast Serbian population. Three hundred panoramic radiographs were analyzed and the horizontal position of the mental foramen was determined according to the reference lines drawn at the longitudinal axes of the first and the second premolar and the mesial root of the first molar. In 62% of the cases mental foramen was between longitudinal axes of the first and the second premolar, in 21% it was in line with the second premolar, in 9% in line with the first premolar, in 8% between the axes of the second premolar and the first molar. The most common shape was round (54%). The horizontal position and shape were asymmetrical in 26% and 32% of the cases, respectively. The most common position of the mental foramen was between the first and the second premolar, while the most common shape was round. Knowledge about variable positions of the mental foramen is important in establishing diagnosis and clinical procedures in the region of the mandible.

Introduction Obturation as the final phase of endodontic treatment aims to provide complete hermetic filling along the entire length of the canal system from the coronal opening to the apical end. The aim of this study was to evaluate histological response of bone tissue on the implantation of zinc oxide based material in artificially prepared defect in the mandible of rats. Material and method For the experiment, sixteen male Wistar rats were used. Using sterile steel burs a defect was made in mandible, between the midline and mental foramen. Zinc oxide based sealer was implanted in the defects of experimental group while the defects of control group healed spontaneously. One half of animals in both groups were sacrificed after thirty days, and the second half after ninety days. Microscopic preparations consisted of the defect with surrounding bone and after processing were analyzed using light microscopy. Results The thirtieth day after implantation of the material, fibrovascular connective tissue was noted, with scant chronic inflammatory cell infiltrate. Away from the experimentally made defect, in the depth of the bone, lamellar bone with well-formed larger osteons was noted as well as enlarged Volkmann and Haversian canals. Ninety days after implantation of the material, there was no restitutio ad integrum, but intense focal remodelling of bone tissue was noted. Conclusion Endomethasone N slowed down bone tissue healing process by showing the signs of prolonged inflammation in bone tissue in which it has been implanted. Extension of the healing process is reflected in the slow replacement of fibrovascular connective tissue with newly formed bone tissue.

Introduction During endodontic treatment smaller or larger areas of root canal wall remain non-instrumented. This can affect prognosis of endodontic treatment as some bacteria may be left behind. The purpose of this study was to evaluate the morphology of non-instrumented areas of the root canal wall using scanning-electron-microscopy (SEM) after completed instrumentation and various irrigation regiments. Materials and Methods Eighteen single-rooted extracted teeth were divided into the six groups. One tooth in each group represented a control sample. In all samples only one half of the canal was instrumented using ISO 40 hand files. Control samples were subjected to an irrigation protocols without instrumentation. Irrigants used were physiological saline, 3% sodium hypochlorite and 15% of ethylene-diamine-tetra-acetate. Irrigation protocol included using each of these irrigants alone, or a combination of NaOCl and EDTA, as well as their combination with final irrigation using NaOCl or chlorhexidine. Then after, roots were sectioned longitudinally and prepared for SEM. Results Saline irrigation left pulpal debris on uninstrumented areas of the canal wall. Irrigation with 3% NaOCl left behind canal wall with different forms of calcospherites. However, after EDTA irrigation dentin appeared as an undulating surface with open tubules without a smear layer. The combination of NaOCl and EDTA showed remnants of calcospherites and open slightly widened dentinal tubules. Final irrigation with NaOCl on the uninstrumented areas showed enlarged dentinal tubules along with dentinal erosion, while after final irrigation with CHX clean dentin and open dentinal tubules without smear layer were noted. Conclusion From the morphological point of view, the most favorable effect of irrigation on both uninstrumented and uninstrumented canal walls was achieved after irrigation with NaOCl and EDTA or NaOCl, EDTA and chlorhexidine as the final irrigant.

The application of irrigating solutions is essential in chemomechanical treatment of tooth root canal. However, chemical and electrochemical aggressiveness of the solutions, which directly act on instruments, may damage their surface. The aim of this study was to investigate the sensitivity of the nickel-titanium (Ni-Ti) and stainless steel endodontic files to corrosive action of the sodium hypochlorite (NaOCl), chlorhexidine gluconate (CHX) and ethylenediamine tetraacetic acid (EDTA). Testing of sensitivity to corrosion of the instruments was performed by dynamic potentiometric method. Measurements were made in 5.25% NaOCl, 0.2% CHX and 17% EDTA. Ni-Ti instruments immersed in 5.25% NaOCl showed the most intensive corrosive changes and the lowest value of pitting potential of 1.1V. Stainless steel instruments immersed in 5.25% NaOCl showed higher value of pitting potential of 1.5V. Stainless steel instruments immersed in 0.2% CHX showed lower corrosive surface changes and higher value of pitting potential of 1.6V, whereas Ni-Ti instruments immersed in 0.2% CHX showed the pitting potential of 1.9V. The corrosion was not observed in both types of instruments after immersion in 17% EDTA. The use of 5.25% NaOCl and 0.2% CHX may cause severe surface corrosion of Ni-Ti and stainless steel endodontic files. [Projekat Ministarstva nauke Republike Srbije, br. 175102]

Introduction Separation (fracture) of endodontic instruments in the root canal during chemomechanical instrumentation is a complication that can compromise the final outcome of endodontic treatment. One of the most common factors that cause fatigue of endodontic instruments and consequent fracture is surface corrosion. The aim of this study was to investigate the ultrastructure of surface corrosion of endodontic instruments made of stainless steel and nickel-titanium after immersion in the most commonly used root canal irrigants. Material and Methods The study included 48 nickel-titanium and stainless steel endodontic hand files. All instruments were immersed in 5.25% sodium hypochlorite, 0.2% CHX and 17% EDTA. Surface corrosion was analyzed using a scanning electron microscope (SEM). Results Nickel-titanium instruments showed significantly higher susceptibility to corrosion after immersion in 5.25% sodium hypochlorite compared to stainless steel instruments (p

Copyright of Natura Sloveniae: Revija za Terensko Biologijo / Journal of Field Biology is the property of Natura Sloveniae and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction. The balance between proinflammatory and anti-inflammatory cytokines plays an important role in the pathogenesis of chronic periapical lesions. The aim of this study was to determine the concentration of TNF-α in tissue homogenates of periapical lesions and analyze its levels in relation to the symptomatology and the size of lesions. Materials and Methods. 93 samples of chronic periapical lesions were obtained after extraction of teeth. Samples were classified according to the clinical presentation as symptomatic and asymptomatic, and according to the size as large and small. The concentration of TNF-α was analyzed using ELISA. Results. The results showed increased production of TNF-α in symptomatic lesions compared to asymptomatic. Higher concentration of TNF-α was demonstrated in large lesions compared to small. Large symptomatic lesions showed greater concentration of TNF-α compared to small symptomatic lesions, while bigger asymptomatic lesions demonstrated higher amount of the cytokines compared to small asymptomatic lesions. Conclusion. Higher concentration of TNF-α in large symptomatic lesions indicates that TNF-α is an important factor responsible for the progression of lesions.

In order to forensic use, dental materials should be sufficiently radiopaque to be detected against enamel/dentin, resulting in correct evaluation of restorations contours, detection of secondary caries, marginal defects, etc. Radiopacity of contemporary composites has been improved by inserting of filler-particles containing heavy metals: aluminum, barium, strontium, zirconium, ytterbium. Tetric composite group (Te-econom, Ceram, EvoCeram) has the most suitable radiopacity; T-econom has highest radiopacity (4.78mm aluminum when exposure-0.6'). The aim of this study was to comparison of MOD composite restorations (T-Econom, Ivoclar, Vivadent) radiographs in molar models and to assess their role in forensic identification, by dental students. Two sets of identical radiographs of molars models (that were previously filled with cement base and composite) were made by standardized technique (exposure-time 0.2ms, amperage-10mA, voltage-70kV). One of the sets consists a few radiographs that did not have their pairs in the second set. Equality of composite restorations on the 'ante-mortem' and 'post-mortem' radiographs were assessed by dental students. Statistical analysis was performed using the kappa test. Results showed (k.t.=0.82) that there is a high correlation of correct answers although estimates are made by students who have no experience in forensic identification and forensic evidence, neither enough knowledge in dental radiology. Although the forensic identification should not be based only on the appearance of the one restoration, or the assessment of non-professional forensic scientists, this study indicates that radiopacity of composites may have a major forensic importance, because 'ante-mortem' and 'post-mortem' radiographs were showed exactly match certain morphological characteristics of composite restorations.

Knowledge of external and internal morphology of the teeth is very important for members of all branches of dental practice. In conservative dentistry knowing external morphological characteristics of dental crowns is significantly because of tendency of certain tooth groups for decay and successful restoration in functional and aesthetic sense. Successful endodontic treatment is impossible without knowing the number and position of the root and root canals inside of them. The variability of the morphology of the human body includes teeth too. Internal morphology features can be analyzed in details only on extracted teeth. In this study, extracted first premolars were analyzed, fifty eight of upper jaw and sixty four of lower jaw. Statistical analysis showed that the average length of the upper first premolar is 21.05 mm and for lower 20.65mm. The upper first premolars usually have two roots. The most common number of channels in the upper first premolar is two. All observed lower first premolars have one root, and in most cases a single channel. The upper first premolar has a higher degree of variation of characters, from the bottom.

Introduction. Although many studies have reported various advantages of nickel-titanium endodontic instruments, the use of stainless steel endodontic files still presents a standard in everyday practice. The aim of this study was to evaluate ultrastructure of the surface of stainless steel endodontic instruments before and after their use. Material and Methods. Fourteen sets of non-used stainless steel endodontic reamers and files were included in the study. Each set of instruments was used one, three or six times in simulated clinical conditions on extracted maxillary premolars. After their use the instruments were subjected to cleaning and sterilization procedures. Ultrastructure of the surface of instruments was observed under scanning electron microscope (SEM). Surface analysis was performed based on the number of uses and size of instruments. The following characteristics were analyzed: defects of instrument flutes, defects of cutting edges and instrument deformations. Results. SEM analysis showed defects on the surface of non-used instruments as a result of the manufacturing process. Surface defects, defects of cutting edges as well as flutes deformations were observed after a single use and were more often noticed in small sized instruments. After three uses, flutes deformations were observed in all small sized instruments and some of the medium size. After six uses all groups of instruments showed defects of cutting edges. Conclusion. Non-used stainless steel endodontic instruments showed surface defects created by the manufacturing process. Defects of cutting edges and flutes can be observed after a single use. To minimize complications and mistakes during clinical preparation it is recommended to limit the number of instrument uses.

Introduction. Clinically acceptable antiseptic should possess organolithic-mineralolithic properties and antimicrobial efficacy, and should be non-toxic. Objective. The aim of the paper was to assess the presence of genomes of the most common microorganisms (Porphyromonas gingivalis, Agregatibacter actinomycetemcomitans, Tanerella forsythensis, Prevotella intermedia, Treponema denticola and Enterococcus faecalis) in infected tooth root canals before and after rinsing with solution of doxycycline, citric acid and detergent Tween-80 (MTAD) in patients with clinically diagnosed primary apex periodontitis. Methods. The content of primarily infected canals before and after using the MTAD solution was used as a biological material in which the presence of microorganisms DNA was proved. For the detection of bacterial genome the multiplex PCR technique was applied. Results. The percentage of positive samples before canal treatment was 100%. In infected root canals E. faecalis was most dominant (37%). In a relatively high percentage we detected P. intermedia (25%), A. actinomycetemcomitans (20%), T. denticola (17%), T. forsythensis (15%) and P. gingivalis (10%). After rinsing the canal system using MTAD solution, there was a statistically significant decrease in E. faecalis (12%), P. intermedia (0%), T. forsythensis (0%) and P. gingivalis (0%). The presence of other bacteria was also diminished but not statistically significantly. Conclusion. With the application of multiplex PCR technique which provided a simultaneous amplification of various genomic sequences, using several pairs of primers, the most dominant in infected root canals were E. faecalis. P. intermedia, A. actinomycetemcomitans, T. denticola, T. forsythensis and P. gingivalis. After mechanic treatment and irrigation of root canals with MTAD solution, P. intermedia, P. gingivalis and T. forsythensis were not found. The presence of E. faecalis, A. actinomycetemcomitans and T. denticola was diminished, however, not statistically significantly.