PubMed · 5290265
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I Imanishi, M Kariyama, M Hosoi, R Matsushima, M Shin. 1971. [Intraenamel microfibril. 2].. https://pubmed.ncbi.nlm.nih.gov/5290265/
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OBJECTIVES: Wear of dental hard tissues, e.g. dental erosion, is reported to be a growing problem. A non-destructive measurement of enamel layer thickness would provide the opportunity for both early diagnosis, and longitudinal measurement of progressive enamel loss. It was the aim of this study to investigate the potential of ultrasonic pulse-echo measurements for the enamel thickness measurement. METHODS: Nine extracted human incisor teeth were selected and stored in physiological saline. Mesial and distal tooth parts were removed, resulting in a central tooth slice of about 2 mm thickness. Where possible three buccal, and one palatal measuring sites were selected and indicated by pencil marks on one of the section planes. Ultrasonic pulse-echo measurements were made at each site using a Panametrics 25DL thickness gauge (Panametrics, Waltham, MA, USA), using a perspex delay line transducer (15 MHz) and glycerine coupling medium. Ultrasonic measurements were validated by measuring the thickness of the enamel layer at the marked side of the tooth slices with a light stereomicroscope at 120 x magnification. Two observers performed independent measurements. RESULTS: Limits of agreement for measurements by two observers (n = 42) were -0.09 and 0.09 mm. Measurements performed at 21 degrees C and 34 degrees C were not significantly different, as analysed by paired Student's t-test (p = 0.19). Pearson's correlation coefficient between ultrasonic and microscopic measurements was 0.90. Analysis of all measurements from both observers at both temperatures yielded a sound velocity in enamel of 6.5 x 10(3) m/s (standard error 0.1 x 10(3) m/s). CONCLUSIONS: It was concluded that the ultrasonic measurement of the enamel thickness is feasible without enamel preparation.
OBJECTIVE: An "enamel pearl" is an ectopic globule of enamel that is adherent to the tooth root surface. Such an anomaly may facilitate the progression of periodontal breakdown. Information on the prevalence of enamel pearls is sparse, and ethnic variations are thought to occur. Our objective was to assess the prevalence of enamel pearls in a group of Jordanian dental patients. STUDY DESIGN: A random sample of 819 dental records were selected, and a total of 1032 periapical radiographs were interpreted for the presence of enamel pearls. RESULTS: Enamel pearls were detected in 4.76% of the subjects and on 1.6% of the molars. No significant difference between sexes was observed. First molar teeth were the most commonly affected, whereas the third molars were the least affected with the condition. CONCLUSIONS: Enamel pearls are not uncommon among Jordanian dental patients, and their early detection could be important in prevention of periodontal disease.
The dental remains of 88 individuals from Old Kingdom, First Intermediate, and Greco-Roman periods at the ancient Egyptian site of Mendes (Tell er-Rub(c)a) were examined for dental enamel hypoplasia, and the results reported here provide some of the first comparative data on enamel defects in ancient Egypt. Overall, 48% of the individuals in the sample have one or more teeth with hypoplasia, with 17% of permanent teeth and 8% of deciduous teeth affected. The permanent teeth account for 87% of the total number of affected teeth, a prevalence over deciduous teeth that is significant at alpha = 0.05. Permanent and deciduous teeth display different patterns of hypoplasia, with the former exhibiting both discrete pitting and linear furrowing, and the latter exhibiting only pits. Teeth with linear defects significantly outnumber those with pits by a factor of more than three to one. Only permanent canines display more than one lesion on a tooth, with a mean of 1.4 defects per affected tooth. Although calculation of the age of insult from lesion position is imprecise, it appears that stress episodes occurred most commonly between approximately 3-5 years of age. The presence of pits in the deciduous dentition, however, suggests that physiological stresses began in utero. There is no statistically significant difference in the frequency of enamel defects between males and females. An observed decrease in the frequency of defects from the Old Kingdom period to the subsequent First Intermediate and Greco-Roman periods is not significant at alpha = 0.05, although such a decrease is expected given epigraphic and other data that refer to prolonged drought and malnutrition in the late Old Kingdom. The calculated chi(2) value of 3.83 is significant at the 0.10 level, however, and since our sample is rather small and the magnitude of the chi-square statistic is a function of sample size, we recommend that future research investigate further the relationship between the frequency of enamel defects and the time period in which they occur.