Microscopic study of dental hard tissues in primary teeth with Dentinogenesis Imperfecta Type II: Correlation of 3D imaging using X-ray microtomography and polarising microscopy.

OBJECTIVES: The aim of this study was to examine the histological appearance of dental hard tissues in primary teeth from children with DI using conventional polarised light microscopy and correlate that with 3D imaging using X-ray microtomograpy (XMT) to gain a further understanding of the dentine structure of teeth diagnosed with dentinogenesis imperfecta. DESIGN: Undecalcified sections of primary teeth from patients diagnosed with Dentinogenesis Imperfecta Type II were examined using polarised light microscopy. XMT was employed for 3D-imaging and analysis of the dentine. RESULTS: The polarised light microscopy and XMT revealed tubular structures in the dentine seen as vacuoles coinciding with the path of normal dentinal tubules but not continuous tubules. The size of the tubules was close to that of capillaries. The largest tubular structures had a direction corresponding to where the pulp tissue would have been located during primary dentine formation. The dysfunctional mineralisation of the dentine and obliteration of the pulp evidently leaves blood vessels in the dentine which have in the main been tied off and, in the undecalcified sections, appear as vacuoles. CONCLUSIONS: Although from radiographs, the pulp in teeth affected by Dentinogenesis Imperfect type II appears to be completely obliterated, a network of interconnected vessels may remain. The presence of large dentinal tubules and blood vessels, or the remnants of blood vessels, could provide a pathway for bacteria from the oral cavity. This might account for why some of these teeth develop periapical abscesses in spite of apparently having no pulp.

Comparison of demineralisation rates in pre- and postnatal enamel and at the neonatal line.

AIMS: The neonatal line, which is an exaggerated incremental layer line, separates pre- and postnatal enamel. It has been suggested that this layer may be a barrier to the progress of a carious lesions. The objective was to measure the rate of demineralisation in pre- and postnatal enamel and within the neonatal layer using scanning microradiography (SMR). Permanent enamel and compressed permeable hydroxyapatite samples were used as controls. METHODS AND RESULTS: Enamel specimens from deciduous incisors were cut into mesiodistal blocks of 2mm thickness without altering the labial surface and located within SMR cells. Permanent enamel and hydroxyapatite specimens were similarly prepared. Artificial caries-like lesions were created by exposing the specimens to 0.1 mol l(-1) acetic acid (pH 4.0) within the SMR cells. SMR was used to measure the rate of mineral loss at 10 points either side of and at the neonatal line in the deciduous enamel, and 20 points across in the control specimens. The rate of demineralisation was almost the same in pre- and postnatal enamel ((6.0-8.0) x 10(-4)gcm(-2)h(-1)), but much lower in the vicinity of the neonatal line (2.0 x 10(-4)gcm(-2)h(-1)). The rate of demineralisation was lower in permanent (5.0 x 10(-4)gcm(-2)h(-1)) than in deciduous enamel, and even lower in the permeable hydroxyapatite specimen (2.5 x 10(-4)gcm(-2)h(-1)). CONCLUSIONS: This study showed no difference in the rate of demineralisation between pre- and postnatal enamel, but a reduced rate within the region that contained the plane of the neonatal line. This supports the hypothesis that the neonatal line may act as a barrier to the propagation of carious lesions.

Molar incisor hypomineralization: a study of aetiological factors in a group of UK children.

OBJECTIVES: The objectives were to investigate the aetiology of molar incisor hypomineralization (MIH), and to discuss previously published studies. SUBJECTS AND METHODS: One hundred and nine children attending the Department of Paediatric Dentistry at the Royal London Hospital were included in the study: 57 children with MIH and 52 controls. Their mothers completed a medical history interview. RESULTS: No significant associations were found with MIH and delivery and birth complications, breastfeeding, immunization history, other illnesses and allergies, general anaesthetics, fluoride history, and trauma or abscesses affecting the primary predecessors. A family history of enamel defects was more commonly reported for MIH children, but the association was not statistically significant. However, MIH was significantly more common among those whose mothers had experienced problems during pregnancy (P = 0.025), those who had chickenpox between the ages of 3 and 3.99 (P = 0.047), and those for whom amoxycillin was the only antibiotic they had received (P = 0.028). CONCLUSIONS: The aetiology of MIH remains unclear, and this study questions whether it is because of a lone aetiological insult. This study recommends further research looking at the links with chickenpox occurring around the third year of life and amoxycillin.

An overview of the dens invaginatus with case examples.

Dens invaginatus is an uncommon dental anomaly in which there is a deepening of the cingulum with infolding of the enamel and dentine. The severity varies, from mild extension into the pulp cavity, to extreme forms in which the invagination extends through the root, resulting in a second opening at or near the apex, and complex morphology. The following cases report on the different management approaches to dens invaginatus and illustrate the difficulties encountered in managing such cases.

Management of postoperative pain in children following extractions of primary teeth under general anaesthesia: a comparison of paracetamol, Voltarol and no analgesia.

OBJECTIVE: The aim of this study was to compare three different pain relief regimes and the respective levels of pain recorded by children undergoing extractions of primary teeth under general anaesthesia. METHODS: This was a tri-sited study carried out in three similar hospital settings, each with a different pain relief protocol. The subjects were 70 children from each site who were aged between 3 and 12 years, and were undergoing routine extractions of primary teeth. All children from the three centres used a self-report visual analogue scale to record pain preoperatively and postoperatively (15 min after recovery), and relevant pain-relief medication was noted. The efficacy of the three different pain relief regimes was then compared. RESULTS: Children reported significantly less pain when rectal Voltarol was provided prior to the extractions, as compared to paracetamol or no analgesia. The greatest amount of pain was reported by the group who had received no analgesia. CONCLUSIONS: Voltarol appears to be the better pre-emptive analgesic for dental extractions under general anaesthesia when compared with paracetamol and no analgesia.