Increased enamel hypoplasia and very low birthweight infants

Birth cohort studies of developmental defects of enamel (DDE) and early childhood caries (ECC) in very low birthweight (VLBW) and normal birthweight (NBW) infants are rare. In this birth cohort of 234 VLBW and 234 NBW infants, we report the incidence of ECC and DDE at 8 and 18-20 mos of corrected age. Infant medical and maternal socio-demographic data were abstracted from medical records at birth. Dental assessments for ECC and DDE (enamel hypoplasia, demarcated and diffuse opacities) were completed at 8 and 18-20 mos. The incidence of hypoplasia was significantly higher in VLBW compared with NBW infants (8 mos, 19% vs. 2%; 18 mos, 31% vs. 8%). The incidence of ECC (International Caries Detection and Assessment System: ICDAS ≥ 2) was 1.4% (8 mos) and 12% (18-20 mos) and was similar between the VLBW and NBW groups. At both ages, using a beta-binomial regression model to control for potential confounders (maternal and infant characteristics), we found increased risk for enamel hypoplasia among the VLBW infants compared with the NBW infants. African Americans had a lower risk for enamel hypoplasia at 18-20 mos. The VLBW infants should be monitored for ECC due to the presence of enamel hypoplasia.

Dental examiners consistency in applying the ICDAS criteria for a caries prevention community trial

AIM

To examine dental examiners' one-year consistency in utilizing the International Caries Detection and Assessment System (ICDAS) criteria after baseline training and calibration.

METHODS

A total of three examiners received baseline training/calibration by a "gold standard" examiner, and one year later re-calibration was conducted. For the baseline training/calibration, subjects aged 8-16 years, and for the re-calibration subjects aged five to six years were recruited for the study. The ICDAS criteria were used to classify visual caries lesion severity (0-6 scale), lesion activity (active/inactive), and presence of filling material (0-9 scale) of all available tooth surfaces of permanent and primary teeth. The examination used a clinical light, mirror and air syringe. Kappa (weighted: Wkappa, unweighted: Kappa) statistics were used to determine inter-and intra-examiner reliability at baseline and re-calibration.

RESULTS

For lesion severity and filling criteria, the baseline calibration on 35 subjects indicated an inter-rater Wkappa ranging from 0.69-0.92 and intra-rater Wkappa ranging from 0.81-0.92. Re-calibration on 22 subjects indicated an inter-rater Wkappa of 0.77-0.98 and intra-rater Wkappa ranged from 0.93-1.00. The Wkappa for filling was consistently in the excellent range, while lesion severity was in the good to excellent range. Activity kappa was in the poor to good range. All examiners improved with time.

CONCLUSIONS

The baseline training/calibration in ICDAS was crucial to maintain the stability of the examiners reliability over a one year period. The ICDAS can be an effective assessment tool for community-based clinical trials.

Student Versus Faculty Performance Using a New Visual Criteria for the Detection of Caries on Occlusal Surfaces: An In Vitro Examination with Histological Validation

One of the first actions that needs to be taken to disseminate the new visual caries detection criteria ICDAS is to assess how it is assimilated by different groups and levels of experience.

Dentition and lesion history

Dental caries is a process that typically keeps recurring throughout life, and the consequences are too often seen as irreversible damage to the dentition. At various stages of life, different parts of the dentition are affected, and the effects continue to be seen in the dentition long after the events took place. They bear witness to previous occurrences of this process throughout the lifetime of an individual. This chapter reviews the linkage between the caries process and the dental caries lesion history of the human dentition. The prevalence and distribution of the caries burden are very variable and closely tied to cultural aspects. In the primary dentition, income and education have been found to be inversely associated with: (1) any early childhood caries and (2) the maxillary incisor caries pattern. A positive association between these caries patterns and minority ethnicity/race status was also identified. These patterns are different from those of the permanent dentition. Well-documented changes in caries prevalence have been observed throughout history, most closely tied to availability and amount of refined sugar consumed. Changes in caries rates are also well documented in the 20th century, mainly with the advent of fluoride in several forms, first as a steep decline and recently as being relatively unchanged. It is likely that there will be dramatic changes in the rates and distribution of dental caries in the future, due to changes in behavioural factors and therapeutic measures. The description drawn is based on the dental caries pattern experienced in modern western societies.

Tooth quality in dental fluorosis genetic and environmental factors

Dental fluorosis (DF) affects the appearance and structure of tooth enamel and can occur following ingestion of excess fluoride during critical periods of amelogenesis. This tooth malformation may, depending on its severity, influence enamel and dentin microhardness and dentin mineralization. Poor correlation between tooth fluoride (F) concentration and DF severity was shown in some studies, but even when a correlation was present, tooth fluoride concentration explained very little of DF severity. This fact calls into question the generally accepted hypothesis that the main factor responsible for DF severity is tooth fluoride concentration. It has been shown previously that genetic factors (susceptibility to DF) play an important role in DF severity although DF severity relates to individual susceptibility to fluoride exposure (genetics), tooth fluoride concentration relates to fluoride ingestion (environmental). The objective of this study was to investigate the correlation between tooth fluoride concentration, DF severity, and tooth mechanical and materials properties. Three strains of mice (previously shown to have different susceptibility to DF) at weaning were treated with four different levels of F in their water (0, 25, 50, and 100 ppm) for 6 weeks. Mice teeth were tested for fluoride by instrumental neutron activation analysis (INAA), DF severity determined by quantitative light-induced fluorescence [QLF], and tooth quality (enamel and dentin microhardness and dentin mineralization). Tooth fluoride concentration (environment factor) correlated positively with DF severity (QLF) (rs=0.608), fluoride treatment group (rs=0.952). However, tooth fluoride concentration correlated negatively with enamel microhardness (rs=-0.587), dentin microhardness (rs=-0.268) and dentin mineralization (rs=-0.245). Dental fluorosis (genetic factor) severity (QLF) correlated positively with fluoride treatment (rs=0.608) and tooth fluoride concentration (rs=0.583). DF severity correlated negatively with enamel microhardness (rs=-0.564) and dentin microhardness (rs=-0.356). Genetic factors (DF severity) and the environmental factor (fluoride concentration in tooth structure) have similar influence on tooth biomechanical properties, whereas only the environmental factor has an influence on tooth material property (mineralization).

Dental fluorosis: variability among different inbred mouse strains

Concurrent with the decline in dental caries has been an increase in the prevalence of dental fluorosis, a side-effect of exposure to greater than optimal levels of fluoride during amelogenesis. The mechanisms that underlie the pathogenesis of dental fluorosis are not known. We hypothesize that genetic determinants influence an individual's susceptibility or resistance to develop dental fluorosis. We tested this hypothesis using a mouse model system (continuous eruption of the incisors) where genotype, age, gender, food, housing, and drinking water fluoride level can be rigorously controlled. Examination of 12 inbred strains of mice showed differences in dental fluorosis susceptibility/resistance. The A/J mouse strain is highly susceptible, with a rapid onset and severe development of dental fluorosis compared with that in the other strains tested, whereas the 129P3/J mouse strain is least affected, with minimal dental fluorosis. These observations support the contribution of a genetic component in the pathogenesis of dental fluorosis.

Detection of early interproximal caries in vitro using laser fluorescence, dye-enhanced laser fluorescence and direct visual examination

This in vitro study evaluated the use of laser fluorescence (LF) for the detection of early interproximal carious lesions and whether the detection could be enhanced using a fluorescent dye (DELF). Direct visual examination (DV) was used for comparison. Eighty extracted teeth were used, arranged in 20 blocks, each block having 2 premolars and 2 molars, lined up in a simulated sextant situation. After cleaning with a microabrasion kit, a subcontact window on half of the surfaces (60) was exposed to Carbopol white-spot solution for 5 days. The teeth were remounted in stone and examined by three independent examiners. For LF and DELF an argon laser was used (mixed wavelength of 488 and 514 nm) viewed through glasses (excluding wavelength <520 nm). For DELF a sodium fluorescein dye (0. 075%) was applied before examination. A clinical examination light was used for DV. The approximal surfaces were scored for lesion presence or absence. To verify lesion presence, the subcontact area was cut perpendicularly to the surface, stained with rhodamine B, and images were taken using a confocal microscope. The images were analyzed using a histogram program for lesion depth and image area. Lesions were present in 62 out of 120 approximal surfaces, with an average depth of 60 microm (range 17-190 microm). Sensitivity ranges for LF, DELF and DV were 56-74, 61-79 and 58-74%, and specificity ranges 67-78, 86-98 and 83-97%, respectively. With this model DELF compared favorably with DV and LF in sensitivity, but specificity was better for DELF and DV than for LF.