Enamel development in primary molars from children with familial dysautonomia

Enamel incremental markings in the deciduous teeth of children from the Early Bronze and modern ages

OBJECTIVE

The purpose of this study was to determine whether children from Early Bronze Age and modern populations differ in terms of the width of the neonatal line (NNL) and the occurrence of accentuated lines in enamel.

DESIGN

The sample (N = 59) consisted of two groups: 29 deciduous teeth removed from the jaws of children (dental age range from 1 to 10 years) whose skeletal remains were found in Early Bronze archaeological graves in Mokrin Serbia, and 30 present-day exfoliated deciduous teeth from 6 to 11 year old children. Mothers, whose children participated in this study, provided information regarding their health during pregnancy. The analysis was carried out on ground sections with a scanning electron microscope. Two clinicians measured the width of the NNL and counted the accentuated lines in the enamel.

RESULTS

There was a statistically significant difference between the children from the two groups regarding the width of the NNL. The width of the NNL between children whose mothers were healthy and diagnosed with gestational diabetes was significantly different. Most subjects did not have accentuated lines in the prenatal enamel, regardless of whether they were from the Bronze or Modern age. Accentuated lines were dominantly found in the postnatal enamel of the children from the Early Bronze age.

CONCLUSIONS

This study is the first to investigate the width of the NNL in teeth of Maros children and Serbian children from the modern age. The wider NNL of children from the Early Bronze age indicates the possibility that they have experienced more overall stress in perinatal life.

Magnesium incorporation into primary dental enamel and its effect on mechanical properties

Cross-sectional study of sound primary dental enamel revealed hardness zonation and, in parallel, significant change in the Mg content below the prismless layer. Mg content is known to play an important role in enamel apatite biomineralization, therefore, Mg ion exchange experiments were carried out on the outer surface of sound primary molars and on reference abiogenic Ca-phosphates using MgCl₂ solution. Effects of Mg incorporation on crystal/particle size, ionic ratio and morphology were compared and the observed changes were explained by parallel diffusion and dissolution/reprecipitation processes. Based on depth profile analysis and high resolution electron microscopy of the Mg-exchanged dental enamel, a poorly ordered surface layer of approximately 10-15 nanometer thickness was identified. This thin layer is strongly enriched in Mg and has non-apatitic structure. Below the surface layer, the Mg content increased only moderately (up to ~3 at%) and the apatite crystal structure of enamel was preserved. As a common effect of the Mg exchanged volume, primary dental enamel exhibited about 20% increase of nanohardness, which is intrepreted by strengthening of both the thin surface layer and the region below due to the decreased crystallite size and the effect of incorporated Mg, respectively. STATEMENT OF SIGNIFICANCE: Dental enamel is the most durable mineralized tissue in the human body, which, in spite to be exposed to extreme conditions like mastication and acidic dissolution, is able to fulfill its biological function during lifetime. In this study we show that minor component magnesium can affect hardness properties of human primary dental enamel. Then, through Mg incorporation experiments we provide an additional proof for the poorly ordered Mg-containing intergranular phase which has been recently observed. Also, we report that the hardness of dental enamel can be increased by ca. 20% by Mg incorporation. These results contribute to a deeper understanding of sound primary dental enamel structure and may inspire new pathways for assisted remineralization of enamel and regenerative dentistry.

Disturbances in primary dental enamel in Polish autistic children

Dental enamel is a structure that is formed as a result of the regular functioning of ameloblasts. The knowledge of the patterns of enamel secretion allows an analysis of their disruptions manifested in pronounced additional accentuated lines. These lines represent a physiological response to stress experienced during enamel development. The aim of this study was to assess the occurrence of accentuated lines in the tooth enamel of autistic boys. The width of the neonatal line and the periodicity of the striae of Retzius were also assessed. The study material consisted of longitudinal ground sections of 56 primary teeth (incisors and molars): 22 teeth from autistic children and 34 teeth from the control group. The Mann-Whitney U test indicates that the accentuated lines were found significantly more often in autistic children (Z = 3.03; p = 0.002). No differentiation in the rate of enamel formation and in the rate of regaining homeostasis after childbirth were found. The obtained results may indicate a higher sensitivity of autistic children to stress factors, manifested in more frequent disturbances in the functioning of ameloblasts or may be a reflection of differences in the occurrence of stress factors in the first years of life in both analyzed groups.

Oral manifestations, dental management, and a rare homozygous mutation of the PRDM12 gene in a boy with hereditary sensory and autonomic neuropathy type VIII: a case report and review of the literature

BACKGROUND

Hereditary sensory and autonomic neuropathy type VIII is a rare autosomal recessive inherited disorder. Chen et al. recently identified the causative gene and characterized biallelic mutations in the PR domain-containing protein 12 gene, which plays a role in the development of pain-sensing nerve cells. Our patient's family was included in Chen and colleagues' study. We performed a literature review of the PubMed library (January 1985 to December 2016) on hereditary sensory and autonomic neuropathy type I to VIII genetic disorders and their orofacial manifestations. This case report is the first to describe the oral manifestations, and their treatment, of the recently discovered hereditary sensory and autonomic neuropathy type VIII in the medical and dental literature.

CASE PRESENTATION

We report on the oral manifestations and dental management of an 8-month-old white boy with hereditary sensory and autonomic neuropathy-VIII over a period of 16 years. Our patient was homozygous for a mutation of PR domain-containing protein 12 gene and was characterized by insensitivity to pain and thermal stimuli, self-mutilation behavior, reduced sweat and tear production, absence of corneal reflexes, and multiple skin and bone infections. Oral manifestations included premature loss of teeth, associated with dental traumata and self-mutilation, severe soft tissue injuries, dental caries and submucosal abscesses, hypomineralization of primary teeth, and mandibular osteomyelitis.

CONCLUSIONS

The lack of scientific knowledge on hereditary sensory and autonomic neuropathy due to the rarity of the disease often results in a delay in diagnosis, which is of substantial importance for the prevention of many complications and symptoms. Interdisciplinary work of specialized medical and dental teams and development of a standardized treatment protocols are essential for the management of the disease. There are many knowledge gaps concerning the management of patients with hereditary sensory and autonomic neuropathy-VIII, therefore more research on an international basis is needed.

The influence of infantile thiamine deficiency on primary dentition

OBJECTIVES

The present study explored the histological and chemical effects of infantile thiamine deficiency (ITD) on enamel development through the examination of exfoliated deciduous teeth from a patient who had been fed during his first year of life with a thiamine-deficient milk substitute.

MATERIALS AND METHODS

Ground sections derived from six exfoliated primary teeth were examined. Slices from a light microscope were photographed for histological analysis. We calculated the time when the amelogenesis insults occurred, and the data were cross-examined with the patient's medical history. We then measured the enamel content of calcium, phosphate, oxygen, carbon, and magnesium on two lines from the dentino-enamel junction (DEJ) to the outer surface using an energy dispersive X-ray spectrometer.

RESULTS

Carbon (organic matter) concentration in postnatal enamel was 2.37 times higher in ITD, phosphate levels were lower, and magnesium and calcium levels tended to be higher in ITD teeth.

CONCLUSION

Chemical and histological analysis enabled us to confirm that thiamine deficiency in infancy impaired postnatal amelogenesis and resulted in less calcified enamel with a higher level of organic matter. Higher postnatal enamel carbon and magnesium concentration found in ITD may derive from either impaired mineralization caused by disturbed cellular metabolism or indirect damage to the ameloblasts due to the physical condition. Ca/P mean ratio in ITD teeth was higher than the mean ratio in the control displaying a damaged mineralization process.

CLINICAL RELEVANCE

This is probably the first description of infantile thiamine deficiency effect on amelogenesis resulting in less calcified enamel.

The effect of the season of birth and of selected maternal factors on linear enamel thickness in modern human deciduous incisors

OBJECTIVE

Development of human tooth enamel is a part of a foetus's development; its correctness is the outcome of genetic and maternal factors shaping its prenatal environment. Many authors reported that individuals born in different seasons experience different early developmental conditions during pregnancy. In this study, we investigated the effects of season of birth and selected maternal factors on enamel thickness of deciduous incisors.

DESIGN

Dental sample comprises 60 deciduous incisors. The parents who handed over their children's teeth for research fill in questionnaires containing questions about the course of pregnancy. All teeth were sectioned in the labio-linqual plane using diamond blade (Buechler IsoMet 1000). The final specimens were observed by way of scanning electron microscopy at magnifications 80× and 320×. The thickness of total enamel (TE), prenatally (PE) and postnatally (PSE) formed enamel was measured.

RESULTS

Children born in summer and in spring (whose first and second foetal life fall on autumn and winter) have the thinnest enamel. Season of birth, number of children in family, diseases and spasmolytic medicines using by mother during pregnancy explained almost 13% of the variability of TE. Regression analysis proved a significant influence of the season of birth and selected maternal factors on the PE thickness - these factors explained over 17% of its variability. Neither of analysed variables had influenced PSE.

CONCLUSIONS

Our findings suggests that the thickness of enamel of deciduous incisors depends on the season of birth and some maternal factors. The differences were observed only in the prenatally formed enamel.

A review of the oro-dento-facial characteristics of hereditary sensory and autonomic neuropathy type III (familial dysautonomia)

The oro-dento-facial features and dysfunction of children with hereditary sensory and autonomic neuropathy type III, known as familial dysautonomia or Riley-Day syndrome, was first described in the scientific literature in 1949. They include dental trauma; dental and soft tissue self-mutilation; normal dental age; normal sequence and timing of eruption and exfoliation of teeth; smaller tooth size; different and disproportional tooth components; normal alveolar bone height; small jaws, mild crowding, and malocclusions. These persons have craniofacial morphology that is different from accepted norms but they resemble norms of their ethnic origin. The subjects can have gray, pale, shiny faces with an asymmetric suffering expression; frontal bossing, with eventual hypertelorism and narrow lips; a low-caries rate; drooling, and hypersalivation. They can have changes in salivary composition and content, which influences plaque and calculus and increases the risk of gingival and periodontal diseases. They also have difficulty in controlling oral muscles; a progressive decrease in number of tongue fungiform papillae, accompanied by lack of taste buds; and specific dysgeusia, but a normal sense of smell.