This study was done to examine the applicability of the Tanaka and Johnston and Moyers’ methods of prediction in Egyptian population and to develop a new prediction method for this specific population if necessary. A total of 325 Egyptian students 145 female, 180 male, mean age 14.4 years, SD±1.1 years were randomly selected from 10 preparatory and secondary schools in Mansoura city, Dakahlia governorate, Egypt during the academic year 2008-2009. The mesiodistal crown diameters of the permanent teeth were measured and compared with the predicted values derived from the Tanaka and Johnston’s equations and from Moyers’ probability tables at 35%, 50% and 75%. Significant sexual dimorphism was found in tooth sizes. There were significant differences between the actual measurements and that derived from the Tanaka and Johnston’s equation and Moyers’ tables. New linear regression equations were derived for both genders to allow accurate tooth size prediction in Egyptians. The correlation coefficients between the total mesiodistal width of the mandibular permanent incisors and that of the maxillary and mandibular canines and premolars were found to be 0.78 and 0.89 in male and 0.63 and 0.87 in female, respectively. It can be concluded that there is a limitation in the application of the Tanaka and Johnston’s and Moyers’ prediction methods to Egyptian population. The developed prediction equation is more accurate for predicting the mesiodistal widths of unerupted canine and premolars of Egyptian population.

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We investigated the effect of the lack of the third molar on synaptogenesis at the neuromuscular junction of masticatory muscles in EL/Sea (Sea) mice, in which tooth bud of all third molars disappears in the process of development. We analyzed the mRNA expression levels of the nicotinic acetylcholine receptor (nAChR) α, ε, and γ subunits at 3, 6, and 12 weeks of age in the masseter and temporalis muscles of Sea mice, and in the control strain EL/Kwl (Kwl) mice, using real-time PCR. In the Sea, no third molars erupted over the oral mucous membrane during the experimental period. In the Kwl, at 3 weeks of age, no third molars had erupted over the oral mucous membrane, but they partially had emerged over the maxilla and mandible and, after 3 weeks of age, completely erupted over the oral mucous membrane. In the masseter, the expression levels of the α, ε, and γ subunit mRNAs in the Sea mice were 92% (P < 0.05), 100% (P < 0.05), and 91% (not significant) higher than in the Kwl mice at 3 weeks of age, but steadily decreased until 12 weeks of age. The expression levels in the Kwl mice were stable throughout the experimental period. In the temporalis and gastrocnemius, there were no significant differences in the expression levels of any of the subunits studied between the Sea and Kwl mice. This result suggests that the difference in the expression of nAChR subunits in the masseter muscle between the Sea and Kwl mice is associated with the eruption of the third molars, and that the absence of the third molars has different effects between the masseter and temporalis.

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We observed changes in the consecutive curve of the incisal edge, tip and cusp tip using serial dental casts from the deciduous to permanent dentition period in the same 44 individuals showing normal dentition at the time of the completion of deciduous dentition. In addition, in both the maxilla and mandible, the curvature gradually increased from the deciduous to permanent dentition period. Changes in the superoinferior position of each measurement site were similar between the normal and crowded dentition groups; however, at 4 measurement sites, the amount of change from the completion of deciduous dentition to immediately before the transition to mixed dentition significantly differed between the two groups (P < 0.01); therefore, using values at the 4 measurement sites, discriminant analysis was performed. When the amount of change at the 4 measurement sites showing significant differences was indicated by variables X₁-X₄, the discriminant function was: Z = 0.1233+1.2588X₁-0.9483X₂+0.0612X₃-0.7749X₄. Normal dentition (Z > 0) could be discriminated from crowded dentition (Z < 0) with a probability of 77.3%. These results suggest that this amount of change is a factor facilitating discrimination between normal and crowded dentition.

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Caries is a major oral disease whose onset and advance in a broad age group is lifestyle-related, but the genetic background of individuals is also a very important factor. Nevertheless, the relationship between caries frequency and genetic background remains unclear, especially for genetic polymorphisms of salivary proteins. The salivary mucin MG2 plays a role in facilitating the clearance of bacteria, interacts with Streptococcus mutans, which may be a caries pathogen, and can function as an antimicrobial agent. Here, we evaluated the statistical relationship of genetic polymorphisms of tandem repeats in the gene encoding MG2 (MUC7) with the frequency of pediatric severe caries in the Japanese population. Genomic DNA from lingual mucosal cells of 70 healthy and 92 caries patients was purified, and the frequency of genetic polymorphisms in MUC7 was evaluated by PCR. The results indicated that alleles of 6 (the most common allele) and 5 tandem repeats were observed in control and caries groups. Differences in the frequencies of polymorphisms were analyzed by Fisher’s exact test. P-values for the frequencies of polymorphisms in MUC7 were as follows: 5-5 versus 5-6 repeats, 0.743; 5-5 versus both 5-6 and 6-6 repeats, 1.00; 5-6 versus 6-6 repeats, 0.254; 5-6 versus both 5-5 and 6-6 repeats, 0.266; 6-6 versus 5-5 repeats, 1.00; 6-6 versus both 5-5 and 5-6 repeats, 0.341. Our data suggest no significant association between genetic polymorphisms in the MUC7 gene and caries susceptibility in the Japanese pediatric population.

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The effects of early tooth extractions on age-associated changes in cognitive function were evaluated. Specifically, teeth were extracted at an early age in senescence-accelerated mice (SAM)P8, and the number of glial fibrillary acid protein (GFAP)-positive astrocytes and spatial perception were evaluated at young, mature, and old ages. The following results were obtained:
1. Concerning spatial perception evaluated by the Morris water maze test, the shortening of the time until the animals reached the platform was significantly slower in mature or old mice of the tooth extraction group compared with age-matched controls. However, no significant difference was noted in the rate of shortening in young mice between the tooth extraction and control groups.
2. The number of GFAP-positive cells was significantly higher in the CA3 region of the hippocampus in the mature or old mice of the tooth extraction group compared with age-matched controls. However, no significant difference was observed in the CA1 and dentate gyrus (DG) region of the hippocampus in the mature or old mice and in the CA1, CA3, and DG region in the young mice between the two groups.
These results suggest that the loss of teeth at an early age accelerated aging and that GFAP-positive astrocytes increased to compensate for a decrease in pyramidal cells.

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The objective of the study was to examine changes in palate section area, palate projection area and palate volume according to age. Using the maxillary dentition models, the palates of 10-, 12- and 14-year old children, who were in the early permanent dentition period, were measured three-dimensionally using the semiconductor laser. Palate section areas between canines, the first premolars, second premolars and first molars became greater as children aged because the palate enlarged vertically with the growth and development of the maxilla. The palate projection area became greater as children aged because the palate enlarged laterally with the growth and development of the maxilla. The palate volume became greater as children aged because the palate enlarged laterally and vertically.

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Mutans streptococci, in particular Streptococcus mutans and Streptococcus sobrinus, are generally considered to be the principal microbial pathogen of dental caries. The objective of the study was to isolate S.mutans and S.sobrinus, identify them by PCR, and to compare their presence with the caries status and caries risk in Mongolian preschool and school children. Forty one preschool children aged 3-5 years and 40 school children aged 12-15 years were enrolled in this study. As assessed using Cariostat test, 75.6% of preschool children had high caries risk and 37.5% of school children had high caries risk. In preschool children, the prevalence of S.mutans and S.sobrinus were 100% and 36.6%, respectively; 63.4% were positive for S.mutans alone and 36.6% were positive for both S.mutans and S.sobrinus. In school children, the prevalence of S.mutans and S.sobrinus were 100% and 25.0%, respectively; 75.0% carried S.mutans alone and 25.0% had both S.mutans and S.sobrinus. The percentage of children positive for both S.mutans and S.sobrinus in the high caries risk group were significantly higher than those in the low risk group of either preschool (42.0% vs. 10.0%, P < 0.001) or school children (46.6% vs. 12.0%, P < 0.001). Moreover, the caries status of children positive for both S.mutans and S.sobrinus were significantly higher than those positive for S.mutans alone (P < 0.01 for preschool children, and P < 0.05 for school children).

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The study was carried out to determine factors affecting oral health care service utilization among a representative sample of junior secondary school children in Ibadan, Nigeria. The study was a cross sectional one in which self administered questionnaire was filled by each student. Data were collected on their socio-demographic characteristics, previous visit(s) to the dental clinic and reasons for the visit(s), reasons for non dental visits for those who have never visited the dentist, the students’ beliefs in regular dental visits and reasons for these beliefs. Only 457 students completed their questionnaires reasonably well and their responses were analysed. Their mean age was 13.04±1.10 years. Over 80% of the children claimed they have never visited the dentist and lack of perceived need accounted for 82.8% of the various reasons given for the non visit. Sixty eight point nine percent of the children believed in regular dental visits while 27.8% of them did not believe in regular dental visits. Equity in access and opportunity for disease prevention among young adolescents may be achieved by school oral health program whereby regular oral health talks/education is instituted.

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Several studies have reported that the prevalence of enamel hypoplasia in pre-term low birth-weight children is higher than that in normal birth-weight children. However, the features of primary teeth dentin in pre-term low birth-weight children are rarely reported. We clinically examined a pre-term very low birth-weight child, and performed histopathological examinations of the extracted primary incisors. Hypomineralized enamel was observed in the permanent upper central incisors, while enamel defects were not detected in primary teeth. In the histopathological examinations, several features of dentin defects, such as irregular dentinal tubules and globular dentin, were observed on the pulpal side of dentin. These findings indicated that dentin formation in the present low birth-weight children was mainly affected during the natal and postnatal periods. Our results provide the evidence that tooth formation in low birth-weight children is affected by postnatal systemic derangement.

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Mesiodens is the most common supernumerary teeth located mesial to both centrals; appearing peg shaped in a normal or inverted position. Their occurrence in the mandibular region is very rare and in the maxilla, most commonly they occur in the premaxillary region. Here we present a case of mandibular mesiodens and a case of midpalatal mesiodens in a seven year old.

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A 10Y2M-old girl was referred to our clinic by a general practitioner for consultation regarding an impacted supernumerary tooth identified in the maxillary left incisor region. Our intraoral examination revealed a maxillary left lateral incisor with a tubercle morphology, with slight swelling identified in the labial gingival area between the lateral incisor and primary canine. The dental age of the patient was calculated to be 1 year behind her chronological age based on root formation observed in orthopantomographs. X-ray photographic examinations revealed an impacted tooth on the labial side, with the root apex presumably directed into the palatal side. Computed tomography (CT) was used to produce three-dimensional reconstruction images in order to obtain morphological information for the impacted tooth, which had a tuberculate shape and an appearance that differed from that of the tooth on the opposite side, which showed a typical morphology of a lateral incisor. Periodical examinations were performed thereafter, which confirmed the developmental progress of the root formation of the impacted tooth. At 11Y8M, the tooth had emerged into the oral cavity and was extracted under local anesthesia. Based on this case, we concluded that effective use of CT is beneficial for consideration of treatment modalities in patients with an impacted tooth.

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In the Japanese population, the second premolars are the second-most-frequently impacted teeth in the mandible, after the third molars. Although some papers have reported on the treatment of impacted mandibular second premolars caused by abnormal tilting of the tooth germ, there has been little information regarding bilateral horizontal impaction with distal inclination. The purpose of the present report is to describe the treatment course of a rare and severe case of an 11-year, 8-month-old girl without any obvious etiologies whose bilateral mandibular second premolars were inclined to the distal direction at approximately 90 degree angles, with the root formation developed to an approximately half length. After extraction of the retained primary molars, traction was performed in the treatment of the affected teeth. The affected premolars had fully erupted and achieved occlusion one year after the beginning of intervention. In conclusion, it was considered that the present case could obtain a successful outcome by limited traction since no clinical anomalies or discomfort was detectable during the one year of retention.

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Radiographically enlarged dental follicle is observed in many cases associated with delayed tooth eruption. Pericoronal radiolucencies are seen in neoplasms (odontogenic fibroma), developmental anomalies (regional odontodysplasia), hamartomatous lesions (odontogenic epithelial hamartoma), opercula of third molars, in follicles associated with unerupted third molars, regional odontodysplasia, in dental follicles around impacted teeth of enamel dysplasia with hypodontia syndrome and amelogenesis imperfecta cases with multiple impactions. Interestingly, operculum and the follicle of these lesions histopathologically are identical to odontogenic fibroma (WHO) type. However, the lack of universally accepted clinic-pathological features for such lesions may hinder their recognition. We report a case of regional odontodysplasia wherein (in which) the impacted canine is surrounded by radiolucency measuring about 1.5-2 cm, histopathologic examination of the excised opercula revealed features reminiscent of central odontogenic fibroma (WHO type) with an abundance of odontogenic epithelium and calcifications. The aim of this paper is to discuss various lesions exhibiting histopathological features similar to odontogenic fibroma, as awareness of the clinicopathological features of such lesions is very important to plan proper treatment.

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Intracoronal resorption in an unerupted developing tooth is rare and most lesions of this type are incidentally found in radiographs taken for other purposes. A 5Y10M-old girl was referred to our clinic by a general practitioner for detailed examination of radiolucency identified in the unerupted mandibular left first permanent molar. Intraoral examination revealed that the affected tooth was unerupted, while the radiographic findings demonstrated a wide radiolucent area in the coronal part of the affected molar, which extended close to the pulp. There were no signs or symptoms associated with the tooth at the first examination. At 6Y4M of age, the affected tooth had emerged into the oral cavity, though the patient reported no symptoms. We performed surgical removal of the gingival tissue corresponding to the occlusal surface of the tooth under infiltration anesthesia and macroscopic appearance showed the affected tooth to be intact. However, when the enamel of the affected tooth was removed, a hollow portion approximately 2 mm into the tooth with no pulp exposure was revealed. Calcium hydroxide was applied to the bottom of the cavity and restoration with cement was performed. Three months after treatment, the patient had no abnormal signs or symptoms. A literature search found 15 similar cases, in which mandibular dentition was more frequently affected than maxillary dentition. As for treatment modalities in those cases, conservative restoration was preferably selected, though extraction was inevitable in approximately half.

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Altered mental status (AMS) is a symptom complex that has various causes and treatments, many of which require timely intervention. Hyperventilation as a component of panic attack may give rise to AMS as it causes a chemical imbalance in the blood. Pediatric dentists must be able to recognize symptoms of AMS which result from hyperventilation and panic attacks and be able to differentiate them from hypoglycemia or diabetic ketoacidosis which may be exhibited in children with both panic attacks and diabetes mellitus.

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Childhood cancer, such as that manifested by neuroblastoma and hepatoblastoma tumors, is one of the leading causes of death for young children. Chemotherapy is one of the most important approaches available, though it is considered to cause tooth developmental disturbances when patients receive treatment during that period of development. Microdontia, disturbed root development, hypodontia and enamel hypoplasia are reported to be possible late adverse effects of chemotherapy. We analyzed 3 children, for whom chemotherapy had been given for treatment of cancer from the ages of 1 to 2.5 years old. Intraoral examinations revealed microdont of the bilateral maxillary lateral incisors and canines in 1 case, whereas that of the bilateral mandibular first premolars was shown in another. Orthopantomograph examinations revealed congenital absence of the first and second premolars in all 3 cases. The developmental period of the affected teeth in these cases appeared to correspond to the chronological age when chemotherapy was administered.

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