Research principles and community health: practice

Question 1

Researchers identify 120 patients with oral cancer and 240 similar patients without oral cancer, then ask both groups about their past use of smokeless tobacco. Which study design is this?

Question 2

A hygienist asks: "In adults with type 2 diabetes and periodontitis, does nonsurgical periodontal therapy, compared with no periodontal treatment, lower HbA1c?" Which part of the question is the C in PICO?

Question 3

Before a community survey, four hygienists probe the same 10 volunteers and compare their readings until they agree closely. What are they establishing?

Question 4

Seven patients report how many dental visits they made last year: 0, 1, 1, 2, 3, 4, 14. Which value best describes the typical patient in this group?

Question 5

Plaque scores in a large group are normally distributed with a mean of 60 and a standard deviation of 8. About what percentage of the group scored between 52 and 68?

Question 6

A caries detection device is tested on 200 tooth surfaces later examined by a reference method. Of the 50 surfaces with caries, the device flagged 40. Of the 150 sound surfaces, it flagged 15. What is the device's sensitivity?

Question 7

Fabricating a removable partial denture to replace teeth lost to periodontitis is which level of prevention?

Question 8

A 13-year-old has 2 permanent teeth with untreated caries, 2 teeth with sound restorations, 1 restored tooth with recurrent caries, 1 first molar extracted because of caries, 1 premolar extracted for orthodontic treatment and 2 sound sealed molars. What is the DMFT?

Question 9

A 45-year-old patient with limited health literacy is starting a prescription fluoride toothpaste. Which approach best confirms that she understands how to use it?

Question 10

A patient who speaks only Vietnamese arrives with her 11-year-old son, who offers to interpret during the medical history and consent discussion. What is the most appropriate approach?

Question 11

A dental hygienist is asked to start an oral health program for adults at a homeless shelter. What should she do first?

Question 12

A program wants to measure whether gingival inflammation decreases among residents of a group home after a daily brushing project. Which index is most appropriate?

Question 13

An oral cancer screening event at a county health fair is an example of which level of prevention?

Question 14

A rural county has very few dentists for its population, and residents travel long distances for care. Which federal designation describes this situation?

Question 15

Which community measure prevents caries in all residents without depending on their income, access to a dentist or daily behavior?

Testlet: a study of an experimental mouthrinse

Researchers recruited 60 adults with plaque-induced gingivitis at a university clinic. A computer program assigned each participant by chance to use either an experimental antiplaque mouthrinse or a placebo rinse that looked and tasted the same, twice daily for 6 months, in addition to usual brushing.

Neither the participants nor the calibrated examiners knew who used which rinse. The examiners recorded the Gingival Index (scored 0 to 3) at baseline and at 6 months. The table gives the group means. The researchers set the significance level at 0.05 and found a p-value of 0.02 for the difference between the groups at 6 months.

Mean Gingival Index by group
Group	Participants	Baseline mean	6-month mean
Experimental rinse	30	1.6	1.1
Placebo rinse	30	1.6	1.5

Question 16

Which study design did the researchers use?

Question 17

What is the dependent variable in this study?

Question 18

Which conclusion about the p-value of 0.02 is correct?

Question 19

By how much did the mean Gingival Index fall more in the experimental group than in the placebo group?

Testlet: planning a school sealant program

A dental hygienist working for a county health department is asked to plan a preventive program at an elementary school in a low-income neighborhood. Most families have no regular source of dental care, and the nearest dental office that accepts public insurance is a 40-minute bus ride away.

Before planning, the hygienist screens a random sample of 10 third graders using a mouth mirror, light and explorer, recording decayed (D), missing because of caries (M) and filled (F) permanent teeth for each child. The results are in the table.

DMFT screening results for 10 third graders
Child	D	F	DMFT
A	3	0	3
B	0	0	0
C	2	3	5
D	4	0	4
E	0	2	2
F	1	1	2
G	3	0	3
H	0	0	0
I	2	0	2
J	3	0	3

The school principal supports a program that would place sealants on the permanent first molars at school, with written parental consent, and refer children with untreated decay to a dental clinic.

Question 20

What percentage of the sample's total caries experience (all DMFT teeth) is untreated decay?

Question 21

Placing sealants on the children's sound permanent first molars is an example of which level of prevention?

Question 22

Two years after the program starts, which measure best evaluates whether it achieved its main outcome?