Linking the clinical presentation of molar-incisor hypomineralisation to its mineral density.

BACKGROUND: The in vitro methods used for the assessment of the severity of molar-incisor hypomineralisation (MIH) are not available for clinicians faced with questions regarding the severity in clinical cases, and the best management approach. AIM: To assess whether there is a relation between the severity of the defects in MIH enamel (represented by reduction in the mineral density) and the clinical presentation (represented by the colour of the defect and its laser fluorescence). DESIGN: The colour of enamel was recorded (normal, white, yellow or brown) in specific areas for ten extracted first permanent molars with MIH defects and ten extracted sound teeth. Laser fluorescence (LF) and mineral density (MD) were measured for the same areas. A mixed model, using sample/tooth as a random effect, was used to estimate the relationship between the MD and the colour-coding, and between the MD and LF readings. RESULTS: The between-samples correlation coefficient for the colour coding and the MD was 0.99 (P < 0.001), and 0.83 (P < 0.001) for the LF and MD. CONCLUSIONS: The degree of staining of MIH enamel, as assessed visually or by LF, may be used clinically to reflect the severity of the defect.

New Zealand dental therapists' beliefs regarding child maltreatment.

OBJECTIVE: To investigate dental therapists' perceptions of the problem of child maltreatment and their roles in child protection, their experience/recollections of past training, and how frequently they suspect (and report) abuse or neglect.  METHODS: Ethical approval was obtained and a postal survey was conducted of all 643 New Zealand (NZ) dental therapists with current annual practising certificates and known addresses. Data were double-entered for accuracy and analysed in SPSS version 20.0. RESULTS: The participation rate was 49.8% (N=320 of 643). Most dental therapists (77.1%) believed rates of death due to child abuse were greater in NZ than other countries. More than 81% desired more continuing professional education courses. During the past year, 18.1% had suspected physical abuse, 30.9% had suspected neglect and 53.1% had suspected dental neglect in their patients. About half of all suspected cases were never reported. The major barrier was a fear of mistakenly reporting a non-abuse case. CONCLUSIONS AND IMPLICATIONS: Most NZ dental therapists believe they have an important role in child protection, yet their suspicions are frequently unreported. Dental therapists may benefit from appropriate support and clear advice from their employers when dealing with suspected cases of maltreatment.

Is it health or the burial environment: differentiating between hypomineralised and post-mortem stained enamel in an archaeological context.

Developmental enamel defects are often used as indicators of general health in past archaeological populations. However, it can be difficult to macroscopically distinguish subtle hypomineralised opacities from post-mortem staining, unrelated to developmental defects. To overcome this difficulty, we have used non-destructive x-ray microtomography to estimate the mineral density of enamel. Using a sample of deciduous teeth from a prehistoric burial site in Northeast Thailand, we demonstrate that it is possible to determine whether observed enamel discolourations were more likely to be true hypomineralised lesions or artefacts occurring as the result of taphonomic effects. The analyses of our sample showed no evidence of hypomineralised areas in teeth with macroscopic discolouration, which had previously been thought, on the basis of macroscopic observation, to be hypomineralisations indicative of growth disruption. Our results demonstrate that x-ray microtomography can be a powerful, non-destructive method for the investigation of the presence and severity of hypomineralisation, and that diagnosis of enamel hypomineralisation based on macroscopic observation of buried teeth should be made with caution. This method makes it possible to identify true dental defects that are indicative of growth disruptions.

Protein content of molar-incisor hypomineralisation enamel.

OBJECTIVES: The aim of the study was to compare the relative amounts and nature of the proteinous content of sound and molar-incisor hypomineralisation (MIH) enamel. METHODS: TCA (20%) was used to dissolve the mineral phase and precipitate the proteins from enamel pieces sectioned from sound and MIH enamel. The protein content was estimated using a miniaturized version of the method of Lowry et al. Samples of the solubilised protein were separated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), stained with Coomassie Blue R250 and tryptic fingerprint/mass spectrometry (MS/MS) of bands in excised gel pieces used for protein identification. RESULTS: Compared to sound enamel, brown enamel showed a 15-21-fold higher protein content, and yellow and chalky enamel showed about 8-fold higher protein content. Tryptic fingerprint/MS performed on excised 50-70kDa areas demonstrated serum albumin, type I collagen and antitrypsin to be common to all types of enamel. Yellow and brown enamel showed more abundant serum albumin and antitrypsin, and the presence of serum antithrombin. Albumin is reported to be an inhibitor of crystal growth, and antitrypsin and antithrombin inhibit kallikrein 4 proteolytic activity. CONCLUSIONS: The combination of the effects of serum proteins on developing enamel may result in elevated proteinous content and reduced mineral content as seen in MIH enamel.