Journal of Dental Medicine

---

Normal 0 false false false EN-US X-NONE AR-SA Eruption is a developmental process in 3 phases of pre-eruptive, prefunctional and functional. Until now there has not been any research on the relationship between eruption and sex and age in Iran in order to compare with the available standards. In This study we recruited 3174 children of 5-8.28 years and eruption sequence in them was evaluated. The results showed that eruption is slightly sooner in girls in comparison to boys which is not statistically significant. The percentage of erupted teeth will increase by increasing age but Maxillary central incisors in boys are the exception. In addition, molars are erupted prior to mandibular centrals.

---

Normal 0 false false false EN-US X-NONE AR-SA During the recent century, the prevalence of dental caries has been changed widely. Therefore, following industrial revolution of Europe in 19th century and industrialization of European countries as well as population increase in the cities and changes in nutritional diets of people, dental caries prevalence has rapidly increased. Thus, by feeling danger and improving awareness, These countries decided to prevent caries. This , lead to a considerable decrease in DMF indices. In developing countries, the situation was reversed and although industrial developments have happened, dental caries prevalence has been gradually increased. In this article, the etiology of these transitions is discussed and analyzed and practical solutions are mentioned.

---

Normal 0 false false false EN-US X-NONE AR-SA Mesiodense have drawn attention of many researchers. According to the available data, there has not been any study on this issue in our country and due to racial variation in Iran, it is essential to evaluate the prevalence of mesiodense in our country. This article has evaluated this on 6-9 years students of Tehran. Complete evaluation is needed according to the lesions that mesiodense can bring about as well as prevention and treatment of this disorder and clinical care following diagnosis. Among 2686 randomly selected students ( 1128f/1559m) , 38 cases in boys and 5 case in girls were found. Therefore, the incidence rate was 5.5 times more in boys which is higher than the other published data. Prevalence of supernumerary teeth was 1.6% of which 88.3% were impacted and only 5.34% were located inversely. In Most cases(93%), single supernumerary teeth were founded.

---

Undoubtedly, Tooth decay is still one of the most significant problems in human communities. Tooth decay is defined as a microbial disease that causes demineralization of hard tissues and degradation of organic components of teeth. Although there are various theories on etiology of dental caries, Miller’s acidogenic theory (1890) and Gottileb’s proteolitic theory (1933) have gained the most credibility among the others. In general, status and amount of saliva, oral hygiene, tooth structure, type and quantity of microorganisms and diet are the most important factors that can lead to tooth decay. Since the manner and type of child nutrition during infancy is considered as a significant factor in development and progression of dental caries and also there has not been published any research on this subject in Iran yet, this study was designed and carried out to find the association between the type of milk intake in infancy and the rate of dental caries in 3-5 year old children.

---

Eruption is a kind of development move of tooth from the place of its formation to its functional position in the mouth.Time and sequence of permanent's teeth eruption from the point of health diagnosis and orthodontic treatments is very important.Because of this, we decided to evaluate and determine the mean eruption time of canine and premolars from gum penetrations toward occlusion and also their sequence of eruption.The average time of eruptions in this study was higher than other similar studies.Our findings showed that the mean eruption time of canine and premolars in girls is earlier than boys lower canines erupt earlier than upper ones and maxillary premolars erupt before mandibular premolars in boys.

---

Anterior tooth crown fracture in children is something that each dentist will confront many times during his professional career.We studied the prevalence of anterior teeth crown fractures between 7-14 years old students in Tehran and some relevant factors like sex, age, the traumatized tooth, amount of overbite and overjet, upper lip coverage, jaw that had fractured tooth or teeth and place of fracture in fractured crown.1338 boys and 1184 girls were in this study. Tooth fracture was almost the same in boys and 1184 girls with the prevalence of 8%. Fracture was mostly in enamel and average year of fracture was 10 years.Increased overjet and overbite had direct relation and indirect relation with fracture, also enough lip coverage showed less fracture.

---

Dental enamel is the end product of amelogenesis, which can be considered to take place in three interrelated phases. When this complex sequence of cytological and physicochemica! events disrupted by genetic or environmental factors, the function of the ameloblasts may be disrupted permanently or temporarily. The result shows qualitative and quantitative defects that may range from a complete absence of enamel or a slight discoloration. The aim of this study was to determine the prevalence of enamel defects by DDE index in a randomly selection group of 1637 students age 7-12 years old in Isfahan (0.2-0.3 PPMF"). Enamel defects were present on one or more teeth in 27% of the cases. The most common affected tooth was the central maxillary and then first molar of maxilla. The most common affected surfaces were buccal. Hypoplastic defects were found in first molar however premolar and canine were affected by diffuse white lines opacity.