Evidence, vital signs and dental age

Correct answer: C. Randomised controlled trial

• A. A case series simply describes a group of patients with no comparison group at all — near the bottom of the hierarchy.
• B. A cohort study follows exposed and unexposed groups forward and yields relative risk and incidence, but without randomisation confounding remains.
• C. Correct. Randomisation distributes known and unknown confounders evenly between groups, so the RCT gives the strongest causal inference of the designs listed.
• D. Case-control studies work backward from outcome to exposure. They are efficient for rare diseases but give odds ratios and are prone to recall bias.

Note: When a systematic review or meta-analysis appears among the options, it outranks the individual RCT. Here it was not offered.

Correct answer: D. Stage 1 hypertension

• A. Hypertensive crisis is above 180 systolic or above 120 diastolic and calls for immediate medical attention.
• B. Elevated blood pressure requires systolic 120-129 AND diastolic below 80. A diastolic of 85 rules that out, and 132 systolic is above the range regardless.
• C. Stage 2 begins at 140 systolic or 90 diastolic.
• D. Correct. Under the 2017 ACC/AHA guideline, stage 1 hypertension is a systolic of 130-139 OR a diastolic of 80-89. This reading meets both criteria.

Note: That is incorrect. The reference table written in the margin of the same file actually contradicts the marked answer — 132/85 is stage 1 by both the systolic and the diastolic criterion. Worth correcting in the group notes.

Correct answer: A. The chronological age is behind the dental age

• A. Correct. Permanent mandibular incisors normally erupt around 6-7 years. Eruption at 5 means development has run ahead of the calendar, so dental age exceeds chronological age — the child's chronological age lags behind.
• B. Eruption timing is one of the standard methods of estimating dental age, alongside calcification staging, which is actually the more reliable of the two.
• C. This reverses the relationship. If the calendar were ahead of development, the teeth would be late, not early.
• D. They do not match here; that is the whole point of the item.

Note: ⚑ Read this stem carefully — the wording asks about the chronological age relative to the dental age, which inverts the intuitive answer. Several group members reported keying it the other way.