مولر اول دائمی

Molar-Incisor Hypomineralizationis (MIH), a developmental enamel defect of incisor and molars, can lead to the fear of dentistry in children. The current study aimed to evalu-ate the dental fears of children aged 8 to 12 years with MIH and children with permanent first molars without hypoplasia using the standard Dental Subscale of the Children’s Fear Survey Schedule (CFSS-DS).

In this descriptive- cross-sectional study, the participants included 200 students aged 8-12 years in Isfahan City, Iran, in 2020. Moreover, the study subjects were selected from the second to sixth-grade students. In total, 52 patients with MIH and 148 patients with permanent first molar without hypoplasia were selected to participate in this research. The CFSS-DS was used to collect the necessary information. The collected data were analyzed in SPSS by descriptive statistical tests.

The Mean±SD CFSS-DS score was obtained as35±15, indicating the average dental fear in the participating children. Moreover, 62.5% of children were afraid of dentistry. The rate of dental fear in girls was 9 times higher than that in boys (P<0.05). Additionally, the rate of dental fear in children with MIH was 46 times higher than that in their counterparts without this disorder (P<0.05). The frequency of dental fear in children with severe disorder was significantly higher than that in children with mild defects (P=0.000).

The fear of dentistry in children with MIH was significantly higher than that in children with molar teeth without hypoplasia.

Ectopic eruption is a disorder in which the tooth does not follow its usual course and if not diagnosed in a timely manner, leads to occlusal problems. The aim of this study was to determine the frequency of ectopic eruption of the first permanent molar and canine in patients referred to Ardabil dental school. By observing the panoramic radiographs, recorded from 2016 to 2017, the frequency of ectopic eruption of first permanent molars in children aged 5 to 8 years and permanent canine in children aged 10 to 13 years was determined. The frequency distribution based on sex, involved jaw, unilaterality and bilaterality were evaluated using Chi-Square test. the frequency of ectopic eruption of the first permanent molar and permanent canine was 2.1% and 6.4% respectively. There was no significant difference in the frequency of ectopic eruption of the first molar, based on the patient's gender (p=0.366), jaw (p=0.132), and unilateral or bilateral involvement (p=0.366).Also, there was no significant difference between the frequency of ectopic eruption of permanent canine and the patient's gender (p=0.384), unilateral or bilateral involvement (p=0.056). The ectopic eruption of the permanent canine in the maxilla was greater than the mandible (p=0.012). In this study, the frequency values of ectopic eruption were 2.1% and 6.4% for the first permanent molar and permanent canine respectively that were in the range of other studies reported from other populations.

Permanent first molars are susceptible to caries due to their particular anatomical form, early development and lack of knowledge of parents about their permanence. This study was conducted to determine the index of first permanent dental careis (DMF6) and some of its related factors in 12 year-old students.
This descriptive-analytical study was carried out on 400 students (200 females and 200 males) using combined method (stratified and cluster sampling) from public and non-governmental schools in Gorgan, northern Iran during 2015-16. First permanent molar examination was carried out. The parent's education level, frequency of toothbrushing and daily consumption of sugar-containing snack foods was recorded in a questionnaire. Each decayed, missing and filled first permanent molar tooth was given number one. These numbers were combined to compute the DMF6 index for each individual.
The DMF6 index was zero in 19.5% and the DMF6 index was determined to be between 1 and 4 in 80.5% of the children. The mean DMF6 index was 2.23±0.07 and significantly higher in girls (2.39±0.10) than in boys (2.07±0.11) (P Dental caries prevalence among 12-years-old students in north of Iran is higher (2.23) than global standard until 2020 (lower than 1). Gender of child, parent’s education, frequency of toothbrushing and consumption of sugar-containing snack foods plays an important role in the rate of dental caries.

The first permanent molar is the biggest permanent tooth having the most important role in chewing, preservation of vertical height of the jaws and esthetics. On the other hand, because of it's special anatomic form, early eruption, lack of mother’s awareness about it’s eruption and misidentifying it from primary teeth, this tooth is very susceptible to caries. Its caries is an indicator for predicting caries susceptibility in the other teeth. The aim of this study was to indicate the prevalence of DMFT in first permanent molar among primary school children in Yazd. In this study, students of totally 6 public and private schools were selected randomly and first the molar tooth of 15 students from each level was examined and DMFT was recorded. Data were then analyzed by SPSS software, ANOVA and t-Test. The least DMFT was identified in 7-year-old students (0.36 ± 0.92) and the highest rate was seen in 11-year-students (1.17 ± 1.26). There was a significant relationship between DMFT and age (P< 0.0001). - Among D,M and F, maximum mean was related to F or filled teeth and minimum was related to M or extracted teeth. - DMFT in girls (1.15 ± 1.33) was higher than boys (0.51% ± 0.88) (P<0.0001). - DMFT among students with lower economical status was significantly higher than those with better economical condition. Increasing DMFT of first permanent molar during 3-4 years after eruption demands attention to early oral education, prevention and treatment of it.

Rotary files may be cause anatomical changes in apical area. The aim of this study was evaluation of maintenance of the canal’s curve using Flex Master and Protaper rotary instruments. In this in vitro study, we used 30 mesiobuccal roots of first permanent maxillary molars with a mean length of 18-23 milimeters and a mean curve of 15-40 degrees. Sampling was simple and the specimens were divided into two groups of fifteen. In each group, the canals were prepared by crown down method after the access step. Then they were prepared using Flex master and Protaper according to their company’s instruction. After finishing the preparation steps, hand instrument number 30 was placed in the canals and under the same primary condition we evaluated the final angle by digital radiographic system. For evaluation of the results, we used variance analysis, t test and covariance analysis. The mean angle of apical transportation after using two Flexmaster and Protaper rotary systems was 6/19±3/07 and 5/52±2/87 degree, respectively. The mean apical transporation using the Flexmaster system was more than Protaper system but the difference between them was insignificant (P>0/ 05). Because of using these two rotary systems, we had apical canal transportation. This transportation by using Flexmaster system was more than the Protaper system, but it was not significant.

Using fissure sealants on the occlusal surfaces of primary and permanent molar teeth is one of the most effective methods in the prevention of caries in children. Because of the certain problems in children such as lack or weakness of cooperation with the dentist, lack of patience in long duration treatments and difficulty in the control of secretary saliva, finding the shortest etching time effective in the retention of fissure sealants and reducing the duration of treatment is an important factor in the success rate of this preventive method.

The research was conducted on 360 molar teeth (200 second primary molars and 160 first permanent molars) in the Shirazian 6-10 year-olds students. After selection of the appropriate teeth not having any decay or enamel hypoplasia or resorption, and after appropriate isolation, the etching procedure in 30, 60, 90 and 120 seconds was done using 37% solution of phosphoric acid. After irrigation for about 30 seconds and drying the tooth for about 20 seconds the sealants is put on the occlusal surfaces of the teeth were and polymerized by the light cure device for 20 seconds. After 3,6 and 9 months follow-up periods, the retention of the fissure sealant material on the both groups of molar teeth was evaluated. The effect of etching time on the retention of this material on the occlusal fissures of the molar teeth was evaluated and the retention of sealants on the primary and permanent molars was then compared.

This study showed that, the most appropriate etching time for both the second primary and first permanent molars was 30 seconds, and the longer the etching time, thelower was the retention of sealant on the mentioned teeth. The first permanent molars were more appropriate for sealant therapy in comparison with the second primary molars and the sealant material is more retentive in this group of teeth.

The most appropriate etching time for sealant therapy of the second primary as well as the first permanent molar teeth is 30 seconds. The retention of sealants in primary second molars is somewhat lower than permanent first molar teeth and all the important factors in different steps of sealant therapy more showed be considered precisely for improving the success rate of this procedure in primary molar teeth.

Epidemiologic studies have shown that caris or "infective damage of hard tissues in teeth" are the most common type of infection in human. In Iran, a few studies have investigated this hygienic problem, but no practical results have been defined yet. In this research, the conditions of the first upper and lower permanent molars (it contains four minor variables), have investigated. For this reason, in a descriptive analytic study, which was of retrospective and cross- sectional type, one thousand files were chosen systematically. The data were analysed by SPSS packages. The mean values of DMFT for permanent first molars were 3.47±0.50 (MT-1.23, FT=0.86, DT-1.38). The number of extracted teeth in mandible was moer than maxilla and the number of untreated caries teeth in maxilla was more than mandible (PO.001). DMFT ratio of the first molars to total DMFT, was approximately 29%, which indicates that caries and that complications on the first molars, make the main part of the overall DMFT. Therefore, hygiene training, preventive methods and the improvement of ecomonical status seem necessary in dental services.

An odontoma is a slow growing and non-aggressive odontogenic tumor composed of enamel, dentin, cementum and pulp tissue. Complex odontomas comprise of an unorganized mass of odontogenic tissues, morphologically not resembling the normal teeth. In this report, a case of rare odontoma in a ten-years-old boy that caused delayed eruption of a maxillary right first permanent molar, buccal expansion of the alveolar plate and a swelling on the palatal surface of this tooth is presented. After consultation with the department of orthodontics and regarding the radiographs of the area, it was decided to extract the tooth. During careful extraction of the tooth just an irregular overlying mass of hard tissue was removed. At this stage, no attempt was made to completely extract mentioned tooth. Histological examination revealed that the hard tissue was a complex odontoma. 3 months follow-up resulted in complete resolution of the swelling and eruption of the tooth which reached to the occlusal plane.