Questions 9-13: In a recent study of dental erosion in 5-year-old children, 190
ID: 3042581 • Letter: Q
Question
Questions 9-13: In a recent study of dental erosion in 5-year-old children, 190 healthy school-attending children were selected for study. The investigators recorded the erosion level on their maxillary deciduous incisors and recorded whether or not their communities used fluoridated water. The results are summarized in the table below:
Evidence of Erosion
No Evidence of Erosion
Total
Non-fluoridated Area
77
37
114
Fluoridated Area
46
30
76
Total
123
67
190
11) What is the incidence rate of erosion for the two groups of children?
12) Calculate and interpret the attributable risk per 100 individuals.
13) Calculate and interpret the relative risk.
14) Calculate and interpret the odds ratio.
15) Based on your data above, does fluoridation appear to increase the risk of dental erosion or provide a protective effect against dental erosion? Justify your response based on your results from question 11. (1 point)
Evidence of Erosion
No Evidence of Erosion
Total
Non-fluoridated Area
77
37
114
Fluoridated Area
46
30
76
Total
123
67
190
Explanation / Answer
Incidence rate of erosion in fluoridated area = (46/76)*100% = 60.52632%
Incidence rate of erosion in non-fluoridated area = (77/114)*100% = 67.54386%
[ Approximately 61 and 68 percent of the children at risk of erosion (under study) belonging to the two groups respectively, had cases of erosion diagnosed.]
Relative Risk = (46/76) / (77/114) = 0.8961039
[ Risk of children having erosions in fluorodite areas in 0.897 times
+> decreased risk of erosion for those have been exposed.
Attributable Risk = ((123/190)*(0.896-1)/(1+(123/190)*(0.896-1)))*100 = -7.218636
Odds Ratio = (46/30)/(77/37) = 0.737 , implying that odds of having erosion when exposed to fuoride is less in comparison to no-fluoride exposure.
Hence, all the measures suggest fluorodisation appear to provide a protective effect against dental erosion.
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