The rise and fall of the alveolar process: Dependency of teeth and metabolic aspects.

The alveolar bone has a unique capacity to follow the teeth's movements. It is formed around erupting teeth and their periodontal ligaments: the more the teeth have erupted, the larger the alveolar process. Throughout life the teeth erupt and migrate in an occlusal and mesial direction to compensate for attrition, an evolutionary trait. After tooth extraction, the alveolar process is resorbed to varying degrees. The mandibular alveolar bone mirrors skeletal bone condition. Due to fast bone turnover (which is the fastest in the whole skeleton), low bone mass and increased fracture risk may first be seen here. If a periapical radiograph of the mandibular premolars shows a dense trabeculation with well-mineralized trabeculae and small intertrabecular spaces, it is a reliable sign of normal skeletal bone density (BMD) and low skeletal fracture risk, whereas a sparse trabecular pattern indicates osteopenia and high fracture risk. The bone turnover rate in the mandible is twice that of the maxilla, and may, hypothetically, play a role in the development of osteonecrosis of the jaw (ONJ), which has been found mainly in the mandibular alveolar process?

Alveolar bone loss in osteoporosis: a loaded and cellular affair?

Maxillary and mandibular bone mirror skeletal bone conditions. Bone remodeling happens at endosteal surfaces where the osteoclasts and osteoblasts are situated. More surfaces means more cells and remodeling. The bone turnover rate in the mandibular alveolar process is probably the fastest in the body; thus, the first signs of osteoporosis may be revealed here. Hormones, osteoporosis, and aging influence the alveolar process and the skeletal bones similarly, but differences in loading between loaded, half-loaded, and unloaded bones are important to consider. Bone mass is redistributed from one location to another where strength is needed. A sparse trabeculation in the mandibular premolar region (large intertrabecular spaces and thin trabeculae) is a reliable sign of osteopenia and a high skeletal fracture risk. Having dense trabeculation (small intertrabecular spaces and well-mineralized trabeculae) is generally advantageous to the individual because of the low fracture risk, but may imply some problems for the clinician.

Dento-alveolar characteristics in adolescents born extremely preterm.

It has been shown that children born extremely preterm (EPT) often suffer from medical complications and growth restrictions in early childhood. Catchup growth diminishes these effects but the children are known to have lower weight, height, and head circumference as school children. Effects on enamel development have been shown. How this affects the dento-alveolar outcome during adolescence is not known. Forty EPT children with a gestational age (GA) of less than 29 weeks, at 12-16 years of age, and matched healthy controls born at term, with a GA of 37-43 weeks, were examined. Data from the clinical examination, dental casts, and bitewing radiographs were collected and compared. Malocclusion was noted, and dento-alveolar length, width, palatal height, and mesio-distal tooth width were measured. Medical diagnoses, neurological, and neuropsychiatric disturbances were noted at the time of the survey. The two groups were compared with an epidemiological normal reference material. The results showed no differences between the controls and reference material. Angle Class II was the most frequent malocclusion associated with morbidity, neurological, and neuropsychiatric disturbances, followed by deep bite and overjet. Three or more malocclusions were almost twice as common among the EPT children compared with the controls. Significantly smaller incisors, canines, and first molars were found. In summary, the EPT children, during adolescence, had medical aberrations as well as dento-alveolar effects opposed to the healthy children born at term. Dentists should be aware of this and treatment plans should be made in due time.

Risk indicators for poor oral health in adolescents born extremely preterm.

Children born extremely preterm often suffer from medical complications that have been shown to affect their oral health as toddlers and school children.The aim of this study was to investigate oral health and possible risk indicators for poor oral health in adolescents born extremely preterm compared with a control group and relate the findings to medical diagnoses at the clinical examination. Also in the same groups, compare the frequency of mineralization disturbances and its relation to postnatal morbidity and treatments. The medical records postnatally,was noted in 45 extremely preterm infants with a gestational age (GA) of <29 weeks, at 12 - 16 years of age and in age and gender matched fullterm controls with 37-43 weeks GA. A dental clinical examination was performed including a salivary examination. Medical diagnoses were noted at the time of the survey. Data from the patient dental records at 3, 6, and 9 years of age was compiled. The findings were related to gestational age, birth weight, neonatal and postnatal medical diagnoses treatments and medical diagnoses at the clinical examination. The result showed that the prevalence of plaque, gingivitis and the occurrence of Streptococcus mutans were higher among adolescents born extremely preterm compared to matched controls, and the saliva secretion was lower in the extremely preterm infants. The frequency of caries did not differ between the groups. Mineralization disturbances were more frequent in the primary dentition and more severe in the permanent dentition among the children born extremely preterm. No association between dental pathology, neonatal and postnatal morbidity and treatments was found. In conclusion, adolescents born extremely preterm have an increased number of risk indicators for a poorer oral outcome compared with the controls and more severe mineralization disturbances. These findings may imply an increased vulnerability for poorer oral health later in life.

Preterm infants--odontological aspects.

Preterm birth is associated with medical complications and treatments postnatally and disturbances in growth and development. Primary and permanent teeth develop during this postnatal period. The overall aim of the present thesis was to elucidate the effects of preterm birth and postnatal complications on oral health and the dentoalveolar development during adolescence, and to study the effects of preterm birth on caries during childhood, in a well-defined group of preterm infants. In the same group, explore the development of the primary and permanent teeth and compare the results with a matched control group and control teeth. The subjects consisted of 40 (45) of 56 surviving infants, born < 29 weeks of gestational age (GA), and matched healthy children born at term. The material consisted of 44 teeth from 14 of the preterm adolescents and 36 control teeth from healthy children. Clinical examinations and dental cast analysis were performed during adolescence and morbidity was noted. Retrospective information from medical and dental records was obtained. Dental enamel was analyzed in a polarized light microscopy, and scanning electron microscopy. Further, chemical analyses of enamel and dentin were performed with X-ray microanalysis. The results showed that during adolescence, more preterms had plaque and gingival inflammation, lower salivary secretion, more S. mutans and severe hypomineralization. Retrospectively, less caries was noted at six years of age, but more children had hypomineralization in the primary dentition. Angle Class II malocclusion, large over-bite and deep bite associated with medical diagnoses were frequent. Furthermore, smaller dental arch perimeters in girls, at 16 years of age, and smaller tooth size in the incisors, canines and first molars were found. The morphological findings were confirmed in the XRMA analyses. In postnatal enamel, varying degrees of porosities > 5% and incremental lines were seen. Lower values of Ca and Ca/C ratio and higher values of C were found. Ca/P ratio in both enamel and dentine indicates normal hydroxyapatite in both groups. No single medical diagnosis, postnatal treatment or morbidity in adolescents could explain the findings. As a conclusion, there are indications for poor oral outcome in this group of preterm infants during adolescence, and disturbed mineralization in primary teeth.

Chemical aspects on dental hard tissues in primary teeth from preterm infants.

Preterm children with very low birth weight suffer from several neonatal and postnatal complications that may affect the mineralization of teeth. Clinical and morphological studies have shown enamel aberrations in teeth from preterm children. In this study, the chemical composition in enamel and dentin was compared in primary teeth from preterm children and full-term children, and the relationship between the chemical composition and the morphological appearance was investigated. Enamel and dentin in 17 exfoliated primary teeth, from 14 children with a gestational age below 29 wk, were investigated and compared with 36 exfoliated primary teeth from full-term children, using X-ray microanalyses (XRMA). In comparison with the teeth from the controls, the teeth from preterm children had a higher relative value of carbon (C), a lower relative value of calcium (Ca), a lower ratio of calcium/phosphorus (Ca/P) and a lower ratio of Ca/C throughout the outer part of the enamel. In dentin, the relative values for P were higher, and Ca/P ratio was lower, at the dentin-pulp junction. The Ca/P ratio indicated normal hydroxyapatite in the crystals in enamel and dentin. The lower ratio of Ca/C in the bulk and outer part of the enamel indicated more porous enamel.

Elemental composition of normal primary tooth enamel analyzed with XRMA and SIMS.

There is an interest to analyze the chemical composition of enamel in teeth from patients with different developmental disorders or syndromes and evaluate possible differences compared to normal composition. For this purpose, it is essential to have reference material. The aim of this study was to, by means of X-ray micro analyses (XRMA) and secondary ion mass spectrometry (SIMS), present concentration gradients for C, O, P and Ca and F, Na, Mg, Cl, K and Sr in normal enamel of primary teeth from healthy individuals. 36 exfoliated primary teeth from 36 healthy children were collected, sectioned, and analyzed in the enamel and dentin with X-ray micro analyses for the content of C, O, P and Ca and F, Na MgCl, K and Sr. This study has supplied reference data for C, O, P and Ca in enamel in primary teeth from healthy subjects. No statistically significant differences in the elemental composition were found between incisors and molars.The ratio Ca/P is in concordance with other studies. Some elements have shown statistically significant differences between different levels of measurement. These results may be used as reference values for research on the chemical composition of enamel and dentin in primary teeth from patients with different conditions and/or syndromes.

Morphological aspects of dental hard tissues in primary teeth from preterm infants.

BACKGROUND: Preterm children with very low birth weight suffer from several neonatal and post-natal complications that may affect the mineralization of the teeth. Clinical studies have shown enamel aberrations in both dentitions. AIMS: The aims of this study were to describe enamel histo-morphology in primary teeth, and investigate the relationship between medical history and morphological appearance. DESIGN: Dental enamels in 44 exfoliated primary teeth, from 14 children with a gestational age below 29 weeks and with a very low birth weight, were investigated, using polarized light microscopy (POLMI) and under a scanning electron microscope (SEM). RESULTS: The neonatal line was found in 1/3 of the sections located coronally of the crown. In the post-natal enamel, 31 teeth showed a degree of porosity higher than 5% with a varying extension. More than half of the teeth showed one or more increment lines. The SEM analysis confirmed the POLMI findings with irregular prisms covered with a structure-less film. CONCLUSIONS: Enamel from primary teeth of preterm children was found to have a high frequency of mineralization disturbances found in POLMI and SEM. The morphological features of the enamel from preterm children do not reflect the disturbances on general growth and development occurred during the neonatal period.