1996;127;1224-1229 J Am Dent Assoc

SM Cameron, WL Whitlock and MS Tabor Foreign body aspiration in dentistry: a review

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FOREIGNP ODY.ASPIRATION INMDENTISTRY:,A REVIE

STEPHEN M. CAMERON, D.D.S.; WARREN L. WHITLOCK, M.D.; MICHAEL S. TABOR, D.D.S.

any complications can arisefrom the routine delivery ofdental care.' These complica-tions include adverse drug reac-tions, allergic reactions to den-tal materials, physical injuryfrom instrument slippage orbreakage and swallowing or as-pirating foreign objects. Any ob-ject routinely placed into or re-moved from the oral cavityduring dental or surgical proce-dures can be aspirated or swal-lowed. These items can includeteeth, restorations, restorativematerials, instruments, implantparts, rubber dam clamps,gauze packs and impression ma-terials. The possibility of swal-lowing or aspirating an object isincreased by the common prac-tice of placing the patient in asupine position for sit-down,four-handed dental treatment.'

Other factors that may in-crease the possibility of aspira-tion include age (a decreasedgag reflex in elderly patients),medical conditions (such asstroke, dementia andParkinson's disease), use oflocal anesthetics and alteredstates of consciousness associat-ed with intravenous sedation.Many reports in the litera-

ture describe the aspiration ofdental instruments, restorationsand prostheses.'-20 In a 33-yearretrospective review, Limper

This article reviews the dangers

of aspirating foreign bodies of

dental origin. Two illustrative

cases are presented, including

an unusual case involving aspir-

ation of an elastomeric impres-

sion material. The authors de-

scribe the techniques used to

identify the foreign body. A ra-

diodensimetric study of four im-

pression materials demonstrates

the difficulty of identifying most

impression materials. The au-

thors also present some strate-

gies for reducing the risk of aspi-

ration during dental procedures.

and Prakash" reported that thesecond most common cause offoreign body aspiration in thelungs was of dental origin.

The consequences of aspirat-ing a foreign object or materialcan range from immediate ob-struction of the airway to long-lasting pulmonary complica-tions. Early complications caninclude hypoventilation of thedistal lung segment with subse-quent atelectasis and hypoxia.Later complications can include

infection, such as lung abscessor pneumonia, and atelectasis."

BARRIER TECHNIQUES

Researchers have described sev-eral strategies to avoid aspira-tion of objects during routinedental treatment.' The easiestand most common procedure forroutine restorative and en-dodontic procedures is the useof the rubber dam,23-27 which of-fers effective protection againstaspiration or swallowing of en-dodontic instruments, brokenburs, restorative materials andpins. While the rubber dam re-duces the risk of aspiration dur-ing restorative procedures, it ispossible for the dam clamp itselfto be aspirated. To reduce thisrisk, Alexander and Delholm7and Meyers28 have suggestedthat dental floss be used to se-cure the rubber dam clamp.Many dental techniques pre-

clude the use of the rubber dam,particularly during routine oralsurgery and prosthodontic pro-cedures. An alternative is toplace a 4 x 4-inch gauze protec-tive barrier in the oral cavitydistal to the area where smallitems are being manipulated.The dentist may also place tem-porary loops on cast restora-tions for tethering the restora-tion with dental floss.29 Dentistsshould also instruct patients

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that if an object falls on thetongue, they should try to sup-press the swallowing reflex andturn their heads to the side.

One prosthetic procedurethat does not easily allow forthe above barrier techniques isfull arch impressions. An im-pression procedure may put apatient at risk of aspirating theimpression material if a largeamount of material and/or low-viscosity material is introducedto the posterior oral cavity.Medical emergencies can arisewhen practitioners hold the pa-tient responsible for managingthis mass if it flows into theoropharynx.Two case reports that illus-

trate the problem of aspirationfollow:

Case 1. During placement ofan amalgam restoration in an85-year-old man, the amalgamwas dropped into the posteriororopharynx and was aspiratedinto the lung (Figure 1). A pul-monologist removed it the nextday without complications usinga flexible fiber-optic broncho-scope.Case 2. As part of a compre-

hensive physical examinationupon his early retirement, a 45-year-old man came to the pul-monary clinic of the Dwight D.Eisenhower Army MedicalCenter, Fort Gordon, Ga., forevaluation of what he thoughtwas a three-year history ofasthma. The patient related ahistory ofwheezing and recur-rent pulmonary infections thatprevented him from performinghis military duties. He had beentreated with bronchodilators,theophylline and corticosteroidsfor the three-year period.On careful questioning, the

patient indicated that he haddental impressions taken theday before the onset of his ini-

Figure 1. Chest radiograph showing amalgam In the right lung ofPatient 1.

Iur 2 Fo XIg b remoVed fro theright ln oI f PI XIat ent 2.lip]

Flgure 2. Foreign body removed from the right lung of Patient 2.

tial symptoms, which causedhim to gag severely. Chest ra-diographs did not show any as-pirated material, and becausethe patient did not have ob-structive pulmonary function, apulmonologist performed bron-choscopy. He located a foreignbody in the right lung and re-moved it with a flexible fiber-

optic bronchoscope.The recovered material was

initially identified by its color andconsistency as well as the dentalhistory ofthe patient (Figure 2).The patient's dental record indi-cated that a maxillary tooth hadbeen prepared for a crown onJuly 20, 1990, and a final impres-sion had been made. The next

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entry, recorded two weeks later,indicated that a new impressionhad been made with polyvinyl-siloxane because ofthe patient'sgagging episode during the firstimpression. To confirm the identi-ty ofthe material, an X-ray spec-troscopic graph ofthe recoveredmaterial was compared with that

ofa sample ofthe impression ma-terial (Figure 3).

DISCUSSION

These case reports demonstratethe importance of radiodensityand mass of any aspirate ofdental origin in regard to itbeing discovered on a chest ra-

Figure 3. Top: An X-ray spectroscopic graph of the material removedfrom the right lung of Patient 2 (unknown material). Bottom: An X-rayspectroscopic graph of polyvinylsiloxane (known material). The x-axisindicates the elements present in the material being analyzed. Eachelement responds to X-rays at a discrete, identifiable energy level. They-axis indicates the relative abundance of each element present.

diograph. While the pulmonolo-gist was able to easily see theamalgam in the first patient, itwas not possible to see the massof impression material in thesecond patient on a routinechest radiograph. Because itwas not clear to us how muchimpression material is neces-sary to be distinguished radio-graphically, we conducted asimple experiment.

Figure 4 demonstrates theradiodensity of four commonimpression materials. Using 10steps of 1.4 millimeters each,we fabricated a step-wedgeblock of each material.

Figure 4 (top left) showspolyvinylsiloxane ("V') impres-sion material. This is a polysilox-ane base and accelerator avail-able in low, medium, heavy andputty consistencies. The basecontains a polymer of low-molec-ular weight and fillers. The ac-celerator is also a low-molecular-weight polymer with vinylterminal groups. The acceleratoralso includes a catalyst of chloro-platinic acid and usually con-tains finely ground palladium orplatinum for the absorption ofhydrogen.30 The inclusion of ametallic catalyst and scavengersmay add slightly to the radiopac-ity of the material.

Figure 4 (top right) showspolyether ("E") impression ma-terial. In these materials, a low-molecular base of polyether ismixed with a catalyst of 2,5-dichlorobenzene sulfonate.30

Figure 4 (bottom left) showsirreversible hydrocolloid ("A")impression material in whichpotassium alginate reacts withcalcium sulfate dihydrate toform an insoluble calcium algi-nate gel when mixed withwater.30 Modifiers such aspotassium zinc fluoride, potassi-um sulfate, or silicates and

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fillers such as diatomaceousearth may be responsible for theslight radiopacity present.

Figure 4 (bottom right) showspolysulfide ("P") impression ma-terial, which is supplied as a

two-part base and acceleratorsystem. The base contains a

polysulfide polymer and titani-um dioxide, zinc sulfate, coppercarbonate or silica. The acceler-ator consists mainly of leaddioxide and dibutyl or dioctylphthalate. Because of the highpercentage of lead dioxide (60 to68 percent)30 in the accelerator,the polysulfide step-wedge blockexhibits significant radiopacity.

As can be seen from the ra-

diographs of all of the impres-sion materials, only the polysul-

fide impression materialdemonstrates any significantradiopacity at a thickness simi-lar to that of the recovered aspi-rated material from Patient 2.

IBy using judiciousairway protection

techniques, practi-

tioners can avoid theproblems encoun-

tered by the patientsand doctors in these

case reports.

By using judicious airwayprotection techniques (Box),practitioners can avoid the prob-

lems encountered by the pa-tients and doctors in these casereports. The use of a rubberdam, with proper precautions, isan effective method of prevent-ing aspiration. If the procedureprecludes the use of a rubberdam, a gauze throat barrier isindicated. It is important to re-

member that the gauze also canbe aspirated31 and should becontrolled by attaching floss or

leaving a long trailing edge ofthe gauze. In all dental proce-

dures, a high-velocity evacua-tion system should be available.

DENTAL IMPRESSIONTECHNIQUES

Dental impressions usually pre-

vent the use of barrier tech-

Figure 4. Raadograpns showing polyvinylsiloxane Impression material (top left), polyether impression mate-rial (top right), Irreversible hydrocolloid impression material (bottom left) and polysulfide impression materi-al (bottom right).

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niques. As a result, dentistsmust rely on other techniquesto prevent airway compromise.Open-mouth impression tech-niques, either maxillary ormandibular, depress themandible, exposing the orophar-ynx to materials initially ex-pelled from impression trays,and allow low-viscosity materi-als to drip or flow into theoropharynx. The closed-mouth,dual-arch impression techniqueallows the tongue to assume anormal position, fill theoropharynx and, in our subjec-tive experiences, force the im-pression materials to the anteri-or of the mouth.

Viscosity of material. Forall impression techniques, werecommend that dentists usethe most viscous material avail-able that will achieve the de-sired level of accuracy for theparticular procedure. A materi-al that ceases to flow when notunder pressure allows the den-tist more control over the im-pression procedure. Low-viscosi-ty materials can be used insmall quantities in conjunctionwith higher-viscosity putty ma-terials to enhance surface re-production and ease removal ofthe impression tray.

I For all impressiontechniques, we rec-

ommend that dentists

use the most viscousmateral avaiable that

will achieve the de-sired level of accura-cy for the particularprocedure.

Custom impression trays.Based on our experience, wealso believe that a custom im-pression tray should be used in-stead of a stock impression tray.This minimizes the amount ofimpression material requiredand directs the material to theareas needed. Leaving thepalate open on a custom maxil-lary impression tray allows thepractitioner to see any excessexpressed material early in theprocedure. If a stock tray mustbe used, it should be modifiedwith modeling plastic or a puttymaterial to reduce the amountof low-viscosity material used.When using open-mouth im-

pression procedures, dentistsshould observe the entire im-pression procedure. This can be

crucial for patients who haverisk factors for aspiration. Thedentist should be prepared touse suction, cotton-tipped appli-cators, a tongue blade, a mirrorhead or a finger to retrieve ma-terial from the oropharynx.Placing the patient in a moreupright position and flexing theneck will also help. The dentistmust also instruct the patienton what to expect and what todo if material begins to flowinto the oropharynx and the gagreflex begins. Telling the pa-tient to bend forward and placethe chin on the chest is, in ourexperience, usually successful.

CONCLUSION

We have described the aspira-tion and ingestion hazards in-volved in dental practice, andsuggested barrier techniques fordifferent procedures. We alsohave presented two case reportsinvolving aspiration of dentalmaterials during a dental proce-dure and described the result-ing medical complications. Thedifficulty in detecting some as-pirated impression materialswith radiographic techniques isunderscored by a simple radio-densimetric study of four com-mon impression materials.When possible, we recommendthat dentists use high-viscosityimpression materials in customimpression or dual arch trays. .

Dr. Cameron is chief, MaxillofacialProsthetics/Dental Oncology, Dwight D.Eisenhower Army Medical Center, FortGordon, Ga. 30905. Address reprint requeststo Dr. Cameron, 4678 Silver Lake Drive,Evans, Ga. 30809-9388.

Dr. Whitlock is chief, Pulmonary andCritical Care, Dwight D. Eisenhower ArmyMedical Center, Fort Gordon, Ga.

Dr. Tabor is an assistant professor,Department of Oral and MaxillofacialSurgery, Medical University of SouthCarolina School of Dentistry, Charleston, S.C.

1. Malamed SF. Medical emergencies in thedental office. 2nd ed. St. Louis: Mosby; 1982.

1228 JADA, Vol. 127, August 1996

$IBAT[GI[S 10: PIIV[N ASPIRATION.ALL PROCEDURES

- Use a rubber dam.~ Uise a gauze throat pack if a rubber dam is not

possible.Use high-velocity evacuation.

IMPRESSION PROCEDURES

- Use a high-viscosity type of material.Us-Te a cuistom tray, with an open-palate design formaxillary trays.OObserve the entire impression procedure.

- UTse a more upright position if possible.- Provide thorough instrtictions to patients.

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