forensic dentistry midterms

8/6/2019 Forensic Dentistry Midterms

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FORENSIC DENTISTRY MIDTERMS

POSTMORTEM DENTAL CHARTING

• Charting of the dental structures is doneafter appropriate photographs, slides andvideotapes are completed.

POSTMORTEM DENTAL CHARTING1. All existing dentition/missing dentition and

restorations

a. Include types of restorativematerials and surfaces restored

b. Include evaluation of periodontalstatus, calculus and stain

c. Tipped, rotated, impacted/partiallyerupted teeth

d. Determination of postmortem lossof teeth

2. Fixed, removable and implant prosthetics3. Identifying marks on any removable

prosthetics.4. Occlusal relationship5. Unique-intra-and interarch characteristics,

including tori6. Unique individual tooth characteristics

7. Radiographic interpretation frompostmortem radiographs including:

a. Presence of endodontic therapyb. Unique presentation of normal

structuresa. dilacerated roots, root morphologyb. pulp stones, pulpal anatomyc. trabeculae, enostosis, exostosisd. sinus morphology

8. Photographic and videotape review9. If indicated, dental impressions should be

taken. Soft tissue abnormalities would bean indication for impressions.

a. Use an ADA approved siliconimpression material

b. Pour in dental stone, NOT plasterc. Pour two sets of each impressiond. Label each set with date, your

name, case number and victimname

e. Label to maintain the chain of evidence

f. Keep the impression materials intheir trays and with the models forfuture use.

RESECTION AND DISSECTION TECHNIQUES

• Remember to follow appropriate guidelinesregarding blood borne pathogens andhandling infectious diseased specimens

when handling any human remains.

• It is best to assume all deceased humanremains are potentially infectious orbiohazardous.

• Proper use of gloves, gowns, masks and eyeprotection is indicated.

RESECTION AND DISSECTION TECHNIQUES

• When working on viewably indentifiablebodies, restricted opening due to rigor willrequire the utilization of methods to accessthe oral structures.

• The dentition can be accessed by intraoralincision of the masticatory muscles, with orwithout fracturing of the condyles.

• The rigor may be broken with bilateralleverage of the jaws in the retro molar padarea.

• Removal of the tongue and/or larynx atautopsy may facilitate the visualexamination of the teeth and placement of intraoral films.

• When dealing with decomposed, incineratedor traumatized bodies, jaw resectionfacilitates dental charting, photographic andradiographic examinations.

• Careful dissection of the incinerated head,

in particular, is required to preserve fragiletooth structures and jaws.

• Radiographs should be made prior tomanipulation of badly burned fragments.

• Mechanical or chemical stabilization of suchtissues should be instituted wherenecessary.

• When conducting a dental examination onskeletonized remains, it is usually notnecessary to resect the jaws.

• The mandible will usually separate from thebase of the skull and a full visualization of the oral structures will be present.

• With proper authorization, body parts may

be resected, preserved and sent to otherfacilities for additional examination andtesting.

• If the remains are to be cremated and thebody is still unidentified, preservation of theoral structures would be indicated.

RESECTION AND DISSECTION TECHNIQUESExtraoral Incisions (facial dissection)

• Extend bilateral incisions from the oralcommisures to the body of the ramus on aline parallel with the plane of occlusion,through the masseter to bone.

• Reflect the soft tissue for access andexamination.

Inframandibular Incision

• Incise the skin inferior and medial to themandible in a direction from the ear acrossthe midline to the opposite ear.

• Reflect the tissue superiorly over the bodyof the mandible to expose the oralstructures. This technique can be used for aviewable victim.

Jaw Resection

• After the skin and tissues have beenexposed and denuded, it is possible toremove the jaws.

• Reflect all soft tissue, including muscle andoral mucosa to expose bone.

• Then use a Stryker autopsy saw to make acut on the ascending ramus of themandible.

• This will free the mandible from the skullexcept for the soft tissue attachments of thetongue and floor of the mouth.

• The maxilla can be removed, if necessary,

by making an incision in the most superiorportion of the maxilla with the Stryker sawblade angled superiorly, again avoiding anyimpacted third molars.

• Start in the most posterior superior part onone side of the maxilla and continue acrossthe midline to the ending spot on theopposite side.

• If a Stryker autopsy saw is not available, amallet and chisel, a piano wire saw orpruning shears make suitable alternatives.

The location of the cuts is the same.

LABELLING AND PRESERVATION OF DENTALEVIDENCE

• Dental hard structures such as teeth andresected or fragmented jaw segments canbe preserved in either 10% formalin orembalming fluid.

• They must be placed in sealed and properlylabeled containers.

• The label must be such that it cannot besmeared, removed or fade over time.

• it must include the case number, date andexaminer bearing the responsibility forstoring the specimen.

• The preservation of soft tissue should notinclude storage in formalin or embalmingfluid.

• These fluids will cause desiccation anddistortion of the tissues, as well as

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dissolving pigmentation or blood byproducts in or under the epidermis.

• Depending on the environment, somepathologists simply freeze the soft tissuespecimens.

LABELLING AND PRESERVATION OF DENTALEVIDENCE

Two such mixtures include:

Two parts 5% acetic acid, four

parts formaldehyde and four partswater. Place tissue is solution,then remove and wrap in towel of solution and store in a labeled ‘Zip-lock’ freezer bag and freeze.

Campden Solution – which is a fruitpreservative available from a localchemist. Place tissue in thesolution, remove and wrap in towelsoaked in solution, place in alabeled ‘Zip-lock’ freezer bag andfreeze.

TECHNIQUES FOR POSTMORTEM DENTAL

RADIOGRAPHY • Postmortem dental radiographs prove

valuable in the comparison of evidence froma missing person’s dental records.

• Best results are achieved when x-rayprocedures are systematic and carefullydone.

• The goal of the forensic dentist is to producex-rays of excellent quality and quantity.

• When an investigation suggests a potentialidentity, that person’s antemortemradiographs should be evaluated as to type,angulation and content.

• The postmortem radiographic effort shouldduplicate the antemortem record in this

regard.

TECHNIQUES FOR POSTMORTEM DENTALRADIOGRAPHY BASIC EQUIPMENT AND SUPPLIES

1. X-ray radiation source2. Film – use double film pack, if possible,

and keep one set with your records.a. periapical/bitewing type filmb. occlusal filmc. lateral plate films of various

sizes, including 5”x7”, 8”x10”3. Film Developing Unit4. Positioning aids for stabilizing dental

remains to be radiographed

a. pedestal (autopsy neck rest canbe used)

b. modeling clay, waded up wetpaper towels

c. string or wax

TECHNIQUES FOR POSTMORTEM DENTALRADIOGRAPHY TECHNIQUE

1. Resected Jaws - position articulated or

unarticulated jaws on pedestal to tubeheight. Secure film to teeth using clay orwas and expose for either bitewing orperiapical views at 10ma, 65-70Kvp for ¼second.

2. Combination Periapical/Bitewing View

(when jaws are not to be removed) – Makeand incision in the tissue medial to theinferior border of the mandible. Slide anocclusal film up the lingual side of the teeth.Secure the film in place as noted above andexpose at 10ma, 65-70 Kvp for ¼ - ½second. This will make a periapical/bitewingfilm.

3. Skeletonized Remains, Jaw Fragmentsand Avulsed Teeth - articulate jaws andsecure with clay. Slide film in as describedin the combination PA/BW technique above.Individual avulsed teeth should be stabilizedand laid on the x-ray film. Expose at 10ma,65 Kvp for ¼ or less seconds.

4. Head In Rigor - use a lateral plate film and

align tube in manner for taking a lateral jawexposure. Expose at 10ma, 65-70 Kvp for 1second. If using an intensifying screen, cutexposure time in half.

5. Panoramic Radiographs – Cover all

surfaces on the machine with plastic wrap.Position head in the machine and secure itin place with clay and floss. Position thehead so the Frankfort Plane is roughlyparallel with the floor and expose film at8ma and 80 Kvp.

BURNED AND INCINERATED REMAINS

• Verification of the identity of burn victimscan be one of the more challenging casesfor the forensic dentist. Much of thedifficulty depends on the condition of thepostmortem dental evidence and the qualityand quantity of the antemorteminformation.

• These are classified in four categories or

degrees:


1. FIRST degree burns: These burns are

superficial with n blistering. As primarily avascular response, this burned area isswollen, red and painful.

2. SECOND degree burns: Some or most of

the epidermis is destroyed; blistering doesoccur and scarring sometimes results.

3. THIRD degree burns: Both the epidermis

and dermis are destroyed and the tissueundergoes massive necrosis. Pain is oftenabsent due to destruction of nerve endings.Scarring always occurs. If the thermalinjuries are extensive, this type of burn isalways fatal.

4. FOURTH degree burns: Charring occurs

with the total destruction of skin andunderlying tissue.

5. “FIFTH” degree burns: Cremated

remains.

• Cremation involves the reduction of a normal adult body to two or threepounds of ashes.

•

These ashes contain recognizablehuman bone fragments. Thisreduction process takesapproximately one to one and onehalf hours at constanttemperatures of 870 – 980º C.


The required time for reduction may beshortened substantially in the frail elderly orinfants and young children. This is due tothe decreased calcification of tissue and thedecreased density and mass of theindividuals.

Usually the forensic odontologist is called to

assist in the identification of third, fourthand fifth degree burn victims because thedestruction of tissue is extensive. This doesnot allow for identification by conventionalmeans of visual recognition or fingerprints.Fortunately, the dental structures areremarkably resistant to thermal, traumaticand chemical insult.


The severity of the burns depends on twovariables: the intensity and the duration of the heat.

These two factors may be influenced bymany variables which include chemicals,

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accelerants, insulators of varying types,location and the accessibility to oxygen.

Chemical fires can quickly reachtemperatures exceeding several hundreddegrees Celsius.

Depending on the supply of burningchemicals, these fires may continue to burnfor hours.

Victims caught in this type of fire may beclassified as a fifth degree burn victim if the

intensity of heat has been maintained overthe required duration of time to causecomplete reduction of human tissue.

House fires generally have slowly risingtemperatures until a flash point is reached.

The fire then spreads rapidly to adjacentareas and reaches its highest temperaturewhere the maximum amounts of fuel andoxygen are available.

The maximum temperature that most housefires attain is 650º C. Seldom do housefires burn long enough to produce fifthdegree burns.

All other degrees, however, can be found.With the use of accelerants, this normal fire

pattern is modified, prolonged andintensified.

One study was done assessing anddocumenting the destruction of an adultbody at a constant temperature of approximately 650º C. The followingchanges to the body over time were noted:

after 10 minutes: the arms arebadly charred.

after 14 minutes: the legs arebadly charred.

after 15 minutes: bones are visiblein the face and arms.

after 20 minutes: the skull and ribs

are exposed after 35 minutes: the bones of theupper and lower legs are exposed.

The victim containing fourth degree burnsover the entire body would appear with thefollowing characteristics. There would becontractures of muscles due to the extremeheat.

The characteristic appearances of fourthdegree burning include a pugilistic attitude,with arms and legs bent and fists clenched.

protruding tongue (due to contraction of facial and neck muscles) and pathologiclong bone fractures.


There may be substantial skin splitting andthe build up of steam from internal fluidsmay result in rupture of the cranial vaultand abdomen. If the extreme temperaturespersist, the body is submitted to progressivedesiccation and then carbonization.

Heat also has an interesting effect on hair.At about 120º C, gray hair turns brassyblond; brown hair at about 93º C for ten tofifteen minutes turns a reddish hue andblack hair remains unaltered with hightemperatures.

DENTAL EVIDENCE IN BURNED VICTIMS

In most badly burned victims (third andfourth degree burns), we see acarbonization of the crowns of the anteriorteeth. They are virtually unprotected whilethe posterior teeth, insulated by layers of skin, muscle and fatty tissue, remainunscathed and are usable for identification

purposes. The effects of fire on the presence and

condition of teeth can give the investigatoran idea of attained temperatures. Otherdental materials can also be indicators. Themelting point of porcelain is 1232ºC.Amalgam and gold melt at 956ºC. Acrylicmelts at a temperature of 600ºC.

Prolonged fire may eliminate the soft tissueinsulation of the posterior teeth.

Evidence found at a scene may befragmented anatomical crowns that haveloosened from underlying dentin and rootstructure.

The insulating factors of the bone and the

relative temperature gradients betweeninfra-bony and supra bony structures causethe fractures to occur.

Rapid dehydration of the surface of theanatomical crown coupled with theexpansion of the organic pulpal tissuewater, increase the likelihood of the supra-bony portion of the tooth loosening from theresidual and infra-bony insulated rootstructure.

Separated anatomical crowns can beidentified.

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forensic dentistry midterms

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