Chapter 17 — Exercises

Work these without looking back at the chapter first; then check yourself. Items marked † have full worked solutions in the answers appendix. There are no answers in this file. Mix of recall, applied reasoning, evidence interpretation, "spot the overstatement," ethics, and a cold-case extension.

A. Recall and definitions

  1. Define forensic odontology in one sentence, and name its one valid core contribution and the one discredited application this chapter contrasts it with.

  2. † Distinguish antemortem records from postmortem records in dental identification. For each, say who creates it, when, and which side of the comparison (the "known" or the "questioned") it plays.

  3. Define dental identification and state, in one sentence, the prior investigative question it answers — the question that must be settled before "who killed him?" can even be asked.

  4. What is dental charting? Explain why a shared charting convention is a precondition for comparing two records at all, not merely a convenience.

  5. Name the three tooth-numbering systems introduced in §17.3 and state, in one phrase each, what distinguishes them. Why is confirming the notation system "step one of any comparison"?

  6. Why is enamel central to the method's value? Give the one physical fact about enamel that makes teeth the identifying tissue of last resort.

  7. List the four conclusion categories an antemortem-to-postmortem comparison can reach (per the American Board of Forensic Odontology's logical structure), and give a one-line trigger for each.

  8. Define an explainable discrepancy versus an unexplainable discrepancy, and state the directional rule (present↔missing) that separates them.

B. Applied reasoning

  1. † A badly burned body comes out of a structure fire: no recognizable face, no printable fingertips, soft tissue gone. List, in order of what you would do, the steps from recovery to a dental-identification conclusion. Name the one recovery hazard specific to burned teeth and the discipline it imposes on the scene team.

  2. The antemortem film on file is three years old. The body shows two teeth missing and a bridge that the old film does not record. Walk through why this is most likely an explainable discrepancy rather than an exclusion, and name the single biological fact that does the work.

  3. † A presumed decedent had "perfect," fully untreated teeth and no dentist of record. A second presumed decedent had extensive, distinctive dental work and a complete recent film set. Which is identifiable by odontology and which may not be — and why does the difference lie in the record, not the teeth?

  4. Explain why matching a single ordinary MOD amalgam between an antemortem and a postmortem chart is weak evidence, while matching a dozen specific features across the whole mouth is strong. Tie your answer to the class-vs-individual logic of Chapter 1.

  5. Radiographic overlay is called the most objective single technique in the method. Name three anatomical features an overlay compares, and explain why overlay is more objective than comparing two written charts.

  6. A dental concordance that would be highly persuasive when deciding between two candidate identities is weaker when searching a pool of 300. Explain the mechanism, and name the statistical error this guards against (the one from Chapter 9).

  7. In a mass-fatality event, dental identification is one of three primary identifiers. Name the other two, and give the single property of teeth that earns dental ID its place among the primaries in fires and high-energy impacts.

C. Evidence interpretation

  1. † Re-read Figure 17.1 ("Two charts of one upper jaw"). The body is missing tooth #5, which the antemortem chart records as present. State (a) whether this is explainable or unexplainable, (b) the physical finding in the figure that resolves it, and (c) what the combination of concordant features — not the #5 discrepancy — supports, and at what strength.

  2. An odontologist's report concludes: "The antemortem and postmortem dental records exhibit concordant features of sufficient quantity and specificity, with no unexplainable discrepancies; in my opinion they are from the same individual." Identify three separate things this sentence does well (where it is appropriately precise or honest).

  3. Re-read Figure 17.2 ("The reconciliation board"). Row PM-014 excludes three candidate antemortem files and concords strongly with a fourth. Explain why the exclusions are, in a sense, the more secure findings on that row — and what additional safeguard mature DVI applies before finalizing the PM-014 identification.

  4. A single tooth recorded in the antemortem chart as crowned is, in the body, plainly sound and never treated. State what this supports, at what strength, and why this one finding can outweigh several concordances pointing the other way.

D. Spot the overstatement / junk-science alert

  1. † A witness, "a board-certified forensic odontologist," testifies that a suspect's teeth "match a bruise on the victim's arm to a reasonable degree of dental certainty." Identify the specific overstatement, name why the shared credential makes it especially dangerous, and give the honest ceiling such testimony may reach today.

  2. An expert testifies: "Dental identification is as certain as DNA." Name two distinct ways this overstates the method, and rewrite the claim honestly using the chapter's placement of dental ID on the validity spectrum.

  3. A television scene shows an examiner glance at a charred jaw and announce a name in seconds. Using §17.1–17.2, give two reasons this is backward from how the method actually works (think: the record, and the sequence of charting).

  4. A report states a positive dental identification but never mentions the provenance of the antemortem records (whose they are, who filed them, whether they were correctly attributed). Why is this a gap a careful analyst — and the cold-case Case File — explicitly keeps in view, even when the dental concordance itself is strong?

E. Ethics and reasoning

  1. † Dental identification "almost always begins with a presumed identity." Using the §17.2 Cognitive-Bias Watch (and previewing Chapter 31), explain the structural confirmation-bias trap this creates, and describe the methodological safeguard (charting the body first, and the "what would make me reject this?" question). Is an identification reached by an examiner who charted blind worth more or less than one reached knowing the expected answer — even when they agree?

  2. The same credentialed expert can give valid identification testimony on Monday and invalid bite-mark testimony on Tuesday. Explain why "Is the witness a qualified odontologist?" is therefore the wrong question, and state the right one. Why can a jury rarely tell the two kinds of testimony apart on its own?

  3. You are asked to testify that a dental identification "proves" the decedent's identity to a metaphysical certainty. Explain why you should decline that verb, what you can honestly say instead, and where the method's residual error actually lives (name the human factors).

  4. The post-fire dentition is fragile, and there is a grieving family and a press presence on scene urging a fast recovery. Explain why "slow is correct" here is an ethical as well as a technical stance, and what is lost if the jaws are recovered like ordinary bone.

F. Synthesis and validity spectrum

  1. † Place these four methods, justifying each, on the NAS 2009 / PCAST 2016 validity spectrum (strong → discredited): single-source nuclear DNA (Chapter 7); dental identification (this chapter); fingerprint comparison (Chapter 14); bite-mark comparison (Chapter 16). Say explicitly where dental ID sits relative to DNA and explain why it is not at the top despite being valid.

  2. Dental identification answers "who is this body?" and the autopsy (Chapter 11) answered "how did he die?" Explain whether either finding depends on the other, using the cold case. Could the identity be confirmed even if the manner of death were unknown — and vice versa?

  3. In one paragraph, explain how this chapter advances at least two of the book's four themes (exclusion over proof; the validity spectrum; cognitive bias; the CSI effect cutting both ways). Name which themes and how. Note that this chapter is unusual in carrying the validity-spectrum theme inside a single specialty.

G. Cold-case extension

  1. † Cold Case. Using only what the dental-identification evidence establishes, write the entry you would add to the Mill Creek evidence log (Appendix I). State (a) the defensible conclusion at its true strength and the honest verb, (b) the prior theory this finding kills, (c) at least three things the identification specifically does not establish, and (d) the provenance caveat you would record alongside the "no unexplainable discrepancies" finding.

  2. Cold Case extension. The dental identification confirmed the body is Marcus Diallo and closed the "someone else's body" insurance/fraud theory. Suppose a skeptic asks, "Couldn't the dental records themselves have been swapped or faked to make a substituted body read as Diallo?" Describe two concrete checks the investigation could run to address that objection honestly, and explain what each adds — and what it cannot rule out.

  3. Cold Case, integrative. The identification settles who the victim is but says nothing about who is responsible. Name two other findings already in the file (from earlier chapters) that the confirmed identity now lets the investigation properly attribute to Marcus Diallo's death — and state plainly why none of this chapter's evidence points at any suspect.

H. Short writing

  1. In 150–200 words, explain to a juror why "the dentist said it's a match" means something fundamentally different for a body than for a bite mark — even when the same expert says it.

  2. † In 150–200 words, contrast the validity foundations of dental identification with those of bite-mark comparison: what does each compare against, what is each one's substrate, where does each sit on the validity spectrum, and what is the single feature most responsible for the gap?