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Aim of the study: Tooth agenesis is very often developmental disorder, its prevalence is the topic of numerous research works. The results of various authors usually differ from each other depending on the methodology and other factors, but one outcome is always the same - the most often missing teeth are the third molars. The aim of our study was to find out the prevalence of the agenesis of the third molars in students of the dentistry program at Palacký University in Olomouc, to compare how often the anomaly is in men and in women, to determine the absence of the third molars in particular oral quadrants, to find out the most often number of the missing third molars and the most often localization and to draw a comparison between this study and the former one which was aimed on the incidence of the tooth agenesis in boys and girls at the age from 13 to 19 and finally to compare our outcomes to the outcomes of the study conducted by Rozkovcová and others (2004). Methods: The study was conducted from 1. 2. 2013 to 30. 6. 2014. Students of the second up to the fifth year of the dentistry program at Palacký University in Olomouc were examined clinically and X-rays were taken to diagnose any tooth agenesis. Only healthy individuals were included in the study. The data received in the examination were statistically evaluated. Results: Our file contained 343 students. The prevalence of the agenesis of one to four third molars was set to 19.26 % in women (47 out of 244 women), 15.15 % in men (15 out of 99 men), for both genders the number was 18.08 % (62 out of 343 individuals). Most of the subjects presented only one missing third molar out of four possible. However statistically significant differences between the absence of one (35 % of individuals), two (26 % individuals), three (16 % of individuals) and four (23 % of individuals) were not detected. The most often missing tooth was the left upper third molar (40 teeth out of 140 total). Nevertheless the differences between the individual locations of the missing teeth were not significant. Conclusion: Our case study showed the prevalence of the agenesis of the third molars in students of the dentistry program at Palacký University in Olomouc. The outcomes were compared with our original study (see Prakt. zub. Lék., roč. 62, 2014, č. 3, s. 35-42) and with the epidemiological research conducted by Rozkovcová and others (2004). The analysis of the collected data showed significantly lower prevalence than the one determined in the file of teenagers (29.71%) signed to regular check ups in Pediatric dentistry department in Dental clinic in Faculty of medicine in Palacky University. Statistically important in the file of students was also lower incidence of cases of missing only one third molar and of cases with missing left lower third molar. The frequency of the incidence of the tooth agenesis published by Rozkovcová and others (2004) (22.14%) was not statistically important. The agenesis of two of the third molars is described as statistically higher.

Aim of the study: Tooth agenesis is very often developmental anomaly. The prevalence of this disorder differs depending on several factors. Different results can be observed in populations on different continents, in different races and genders, and in primary and permanent dentition as well. What is more, the results are influenced by the quality of the file, methods applied during the research and definitions of particular terms. The aim of our study was to determine the prevalence of agenesis of teeth except third molars in students of dentistry program at Palacký University in Olomouc, to compare the frequency in women and men, to set the frequency of lesion of particular morphological classes of the teeth and to compare the results with our former work focused on the frequency of tooth agenesis in girls and boys at the age from eight to nineteen and with other studies. Material and methods: The study was conducted from 1.2.2013 to 30.6.2014. Students of the second up to the fifth year of dentistry program at Palacký University in Olomouc were examined clinically and X-rays were taken to diagnose tooth agenesis. Only healthy individuals were included in the study. The data received in the examination were statistically evaluated. Results: 343 students (244 women and 99 men) were examined. The agenesis of at least one tooth excluding third molars was observed in 22 individuals (18 women and 4 men), the prevalence was set on 6.41% (7.38% in women, 4.04% in men). Total number of missing teeth was 40, that is 1.82 of missing tooth in one individual. The highest number of missing teeth was five, no one missed more than six teeth. The most often missing teeth were second lower molars. Conclusion: Our case study demonstrates the prevalence of agenesis except third molars in students of dentistry program at Palacký University in Olomouc. The results were compared with our former study, and with epidemiological investigation conducted in the Czech Republic in 1970s (Racek J. a kol. 1979, Marková M., Taichmanová Z. 1985), and with foreign studies (Bäckman B., Wahlin Y.B. 2001., Polder B.J. a kol. 2004). Statistically significant lower prevalence was observed in the incidence of the agenesis on upper lateral incisors in comparison with children and adolescents in Olomouc region and in the studies conducted by Bäckman and Wahlin. The rest of the results were not statistically significantly different.

Background: Tooth agenesis represents the most common anomaly of dental development, which according to Online Mendelian Inheritance in Man (OMIM) database, affects approximately 20% of the population. Although the anomaly is so common, the ethiology is still undisclosed. In most cases the agenesis is caused by genetic disorder, only a few develop due to external factors. Some of the external factors are rubeolla, syphilis, vitamin D deficiency or nutritional damage during pregnancy and early childhood. Other harmful factors are radiation therapy in orofacial area in early stages of the development of the patient, harms the mother caused by radiation, chemical substances or drugs (e.g. thalidomide, cytostatics). Local factors include various types of injuries, tumors and osteomyelitis. Hypodontia can occur as an isolated condition (non-syndromic hypodontia) or can be associated with a systemic condition or syndrome (syndromic hypodontia). Despite the fact that, tooth agenesis is so common, little is known about the genetic defects responsible for this complex condition. To date, the genes associated with the non-syndromic form of tooth agenesis, listed in OMIM, are MSX1 (muscle segment homeobox gene 1), PAX9 (paired box gene 9), AXIN2 (axis inhibition protein 2), EDA (ectodysplasin A), WNT10A (Wingless-type MMTV integration site family, member 10A) and LTBP3 (latent transforming growth factor beta binding protein 3). Cases with selective tooth agenesis caused by mutation in genes EDARADD (EDAR-associated death domain), NEMO (nuclear factor-kappaB essential modulator), KRT17 (keratin 17) and TGFA (transforming growth factor-alfa), were also published. All these genes vary both in terms of number of identified mutations and in terms of number of documented patients. These mutations explain the formation of tooth agenesis in only a part of affected individuals. Most patients have no defects in these genes. To select other genes, that are responsible for non-syndromic forms of hypodontia, the identification of genes that cause syndroms with symptoms of hypodontia, seems as reasonable direction of further research.

Aim of the study: Third molars have a special position in dentition. The reasons of this are extreme deviations in the developmental process, together with frequent agenesis of third molar. Their absence is considered normal very often. This paper aims to investigate the epidemiology of agenesis of third molars in children in the Olomouc Region, to compare its frequency in boys and girls, to determine the prevalence of agenesis of third molars of different localization, to compare its frequency in upper and lower jaw and in right and left side and to make comparisons with Rozkovcová et al. study. Material and methods: The study was conducted from 1. 10. 2010 to 1. 2. 2013 at the Pediatric department of Institute of Dentistry and Oral Sciences of Faculty of Medicine and Dentistry of Palacký University Olomouc. It included boys and girls aged between 12 and 19 years. Clinical and radiographical evaluations were carried out. Age, gender, systemic diseases, syndromes, number and localization of missing third molars were recorded. Results: We worked with two groups of probands. The first consisted of 218 children aged between 12 and 19 years, the second consisted of 175 probands aged between 13 and 19 years. In the first, agenesis of third molars was found in 62 patients, the prevalence was set at 28.44%. In the second, agenesis of third molars was found in 52 patients, the prevalence was set at 29.71%. The difference between the values was not statistically significant. The majority of patient didn't have only one or two third molars. Most often missed upper left third molar. In our group of patients, who had agenesis of one to four third molars, we found a significantly higher prevalence of agenesis of other teeth, than in patients with established all four third molars. Conclusion: The two-year study showed the prevalence of agenesis of third molars in boys and girls in Olomouc region at present. The results were compared with epidemiological investigations published by Rozkovcová et al. Most of the results were not significantly different.

Aim of the study: Many developmental anomalies can occur in craniofacial region. Dental developmental anomalies, namely hypodontia, are the most often of them. The prevalence of agenesis in permanent dentition (excluding third molars) in European population is 5,5%. The aim of our study was to determine the prevalence of agenesis of teeth except third molars in pediatric patients in the Olomouc Region, to compare its frequency in boys and girls, to determine the prevalence of agenesis of teeth of different morphological classes and to make comparisons with other available studies. Material and methods: The study was conducted from 1. 10. 2010 to 1. 2. 2013 at the Pediatric department of Institute of Dentistry and Oral Sciences of Faculty of Medicine and Dentistry of Palacký University Olomouc. It included 434 persons aged between eight and 19 years. Clinical and radiographical evaluations were carried out. Age, gender, systemic diseases, syndromes, number and localization of missing teeth were recorded. Results: Prevalence of agenesis of teeth except third molars was set at 12.04% for girls, at 7.41% for boys, at 9.45% for both sexes together. Only one or two teeth were missing in 85% of persons. The highest number of missing teeth was four, nobody showed agenesis of five or more teeth. The most often was the absence of lower second premolars, which was founded in 20 patients (prevalence 4.61%), followed by the upper lateral incisors (prevalence 3.69%) and upper second premolars (prevalence 2.53%). Conclusion: The two-year study showed the prevalence of tooth agenesis except third molars in pediatric patients in the Olomouc Region. The results were compared with Czech epidemiological investigations published in 1970s and with foreign studies. Most of the results were not significantly different.

Aim of study: Tooth agenesis means absence or incomplete development of tooth. It is the most common developmental dental anomaly in man. The prevalence of agenesis in permanent dentition (excluding third molars) in common population oscillates between 2.6% and 11.3%. It is frequently associated with other dental developmental anomalies. Reasons of this are complex interactions of gens. The same genetic defect may give rise to different phenotypes, including tooth agenesis, microdontia, peg-shaped lateral incisor, palatally displaced canines, taurodontism and delayed formation and eruption of other teeth. This paper aims to investigate the epidemiology of tooth absence (excluding third molars) and associated dental anomalies in the Olomouc Region. Material and methods: Study was conducted at Institute of Dentistry and Oral Sciences, Faculty of Medicine and Dentistry, Palacký University Olomouc from 1. 10. 2010 to 1. 2. 2013. For this study, patients aged between eight to 19 years were selected. Clinical and radiographic examinations were performed. Results: Tooth agenesis was found in 41 of 434 individuals, 18 boys, 23 girls (prevalence 9.45%), excluding third molars. 95% of these 41 patients had at least one of the other dental developmental anomalies. Persistence of deciduous molars (prevalence 56.25%), peg-shaped lateral incisor (prevalence 14.29%), infraocclusion of deciduous molars (prevalence 12.50%) and taurodontism (prevalence 12.20%) were the most often other dental developmental anomalies. Conclusion: The results were compared with the results of similar domestic and foreign studies. There are no statistically significant differences between the results of these studies in the levels of prevalence of agenesis of teeth except third molars. Statistical comparison of other developmental anomalies was not possible because of differences in the methods of the research.

Background: Ectodermal dysplasia is a rare, genetically determined disease, which is characterized by alterations in two or more ectodermal structures, at least one of these involving alterations in hair, teeth, nails, or sweat glands. It is estimated that about seven in 10 000 births are affected with a form ectodermal dysplasia. The cause of the disease is mutation of genes, which can be found in Eda/NF-KB (nuclear factor kappa B) pathway. We recognize two main forms of the disease: hypohidrotic ectodermal dysplasia and hidrotic ectodermal dysplasia. Most cases of hypohidrotic ectodermal dysplasia are related to the sex and caused by the mutation in EDA with gene localization Xq12-q13.1. Lower number of cases is autosomally recessive or dominant with the mutation in EDAR or EDARADD with gene localizations 1q42.2-q43 or 2q11-q13. The small subclass is sex related recessive hypohidrotic ectodermal dysplasia with immunodeficiency. It relates to the IKK-gamma gene mutations which encodes nuclear factor-kappaB essential modulator (NEMO) with the gene localization is Xq28. Hypohidrotic ectodermal dysplasia is characterized by hypotrichosis (sparseness of scalp and body hair), hypohidrosis (reduced ability to sweat), and hypodontia (tooth agenesis). In the X-linked recessive form of hypohidrotic ectodermal dysplasia, males are usually more severely affected, and females show variable severity, ranging from mild to severe. The most characteristic findings in man are the reduced number and abnormal shape of teeth. The scalp hair is thin, lightly pigmented, and slow-growing. Skin is thin, glossy, smooth, and dry with hypohidrosis. Another type is autosomally dominant hidrotic ectodermal dysplasia, Clouston syndrome with the gene localization 13q12. In contrast to the above described hypohidrotic ectodermal dysplasia ED1, the normal function of sweat and sebaceous glands is maintained.