Volume 14, Number 4, 2001The International Journal of Prosthodontics 364

The gag reflex is a normal healthy physiologicmechanism that prevents foreign objects or nox-ious material from entering the pharynx, larynx, or tra-chea.1 The reflex is triggered when the region of thesoft palate or the posterior third of the tongue is stim-ulated.2 Impression taking can be very annoying to pa-tients when the gag reflex is triggered. Several meth-ods have been introduced to help both the patient andthe dental practitioner during this dental procedure.

These methods include local or general anesthesia,3,4

inhalation sedation using nitrous oxide,5 psychologicand behavior management procedures,68 mechani-cal prevention technique,9 hand pressure point andacupuncture,10,11 barbiturates to depress the centralnervous system,2 antihistamines to reduce the feelingof sickness, and parasympathetic depressants to re-duce the salivation.2 Finally, a method using table saltspread for 5 seconds on the tip of the tongue appearsto eliminate the gag reflex.12 The idea seems interest-ing and easy, but no clinical trial was published to sup-port this theory. The aim of this pilot study was to com-pare the efficiency of table salt in extending the timeto gag reflex triggering with a method using inhalationsedation with nitrous oxide.

Materials and Methods

Fifteen healthy volunteers (eight men and sevenwomen aged 19 to 22 years, mean age 20.6 years)with no previous history of gagging problems agreed

Purpose: The objective of this study was to compare two methods for reducing gagginginduced by stimulation of the soft palate: table salt and nitrous oxide inhalation sedation.Materials and Methods: Fifteen healthy volunteers, eight men and seven women with amean age of 20.6 years, were subjected to a gagging event three times using a largetablespoon to stimulate the soft palate: event 1 = spoon alone, event 2 = spoon and tablesalt on the tip of the tongue with a 30-minute break between events 1 and 2, and event 3= spoon and nitrous oxide sedation on another day. Time in seconds was measured fromthe moment the spoon touched the soft palate until gagging was felt using a chronometerheld by the subject. Results: The mean time for eliciting the gagging reaction was 7.7seconds for the spoon alone, 8.9 seconds for the spoon and table salt, and 24.0 secondsfor the nitrous oxide sedation. Nitrous oxide inhalation sedation significantly (P < .001)reduced the gagging/retching reaction, whereas there was no significant time differencein gagging reaction between stimulation with the spoon alone or when table salt wasadded. Conclusion: Within the limits of this study, table salt did not seem to reduce thetime to triggering the gag reflex, whereas nitrous oxide had a substantial effect. Int JProsthodont 2001;14:364366.

aAssistant Professor, Prosthodontics Department, School ofDentistry, Lebanese University, Beirut, Lebanon.bClinical Instructor, Prosthodontics Department, School ofDentistry, Lebanese University, Beirut, Lebanon.cVisiting Professor, Prosthodontics Department, School ofDentistry, Lebanese University, Beirut, Lebanon.

Reprint requests: Dr Jos Chidiac, PO Box 40105, Baabda,Lebanon. e-mail: RJCHID@cyberia.net.lb

Port ions of this ar t ic le were presented at the EuropeanProsthodontic Associations 24th Annual Conference, Groningen,The Netherlands, 2326 August 2000.

Gagging Prevention Using NitrousOxide or Table Salt:

A Comparative Pilot Study

Jos Johann Chidiac, DChD, MSc, Ass Etr Fac Meda

Loubna Chamseddine, DChD, DESS Protheseb

Georges Bellos, DDSc

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Gagging Prevention Using Nitrous Oxide or SaltChidiac et al

The International Journal of ProsthodonticsVolume 14, Number 4, 2001 365

to participate in the study. Each subject was sub-jected to a gagging event three times using a large ta-blespoon to stimulate the soft palate. Time in secondswas measured from the moment the spoon touchedthe soft palate until gagging was felt using achronometer held by the subject. In the first event, thegag reflex was triggered using the spoon alone with-out salting the tongue or using inhalation sedation.This procedure was performed on all subjects. Abreak of 30 minutes separated this event from the sec-ond one. During the second phase, the gag reflex wastriggered using the same protocol, but this time tablesalt was spread on the tip of the tongue of each sub-ject 5 seconds before starting the gagging experi-ment. The final part of the experiment, the third event,was run 2 days later with the same protocol, exceptthat the subjects were under nitrous oxide inhalationsedation before starting stimulation of the gag reflex.Inhalation sedation was given following internationalstandards regulations.13

The data from the three eventsspoon alone(group 1), spoon and table salt (group 2), and spoonand nitrous oxide (group 3)were analyzed statisti-cally by means of the paired t test.

Results

The first experimental event with the spoon alone(group 1) was taken as a control group, and time in sec-onds needed to trigger the reaction gave the basicvalue of comparison, mean time 7.7 seconds. These re-sults were compared to the spoon and table salt (group2), mean time 8.9 seconds, and to the spoon and ni-trous oxide (group 3), mean time 24.0 seconds. Usingnitrous oxide prolonged the gag reflex about threetimes in comparison with the first two experiments (P< .001; Table 1). The difference between means ofpaired samples using the t test was not significant be-tween groups 1 and 2 (P > .2), while the difference be-tween groups 3 and 1 was significant (P < .001).

Discussion

Although the gag reflex is a physiologic protective re-flex, it can become very disturbing to some patientsand cause dental fear.14 These patients are sensitiveto a broader variety of stimuli and show precursorsand aftereffects of retching/vomiting that are notfound in the normal population.14

For this reason, the sample was restricted to a nor-mal population, enabling us to test the efficiency ofthe two methods. It has been suggested that table saltdepresses the gag reflex by a superimposed simulta-neous stimulation of the chorda tympani branches tothe taste buds in the anterior two thirds of the

tongue.12 This could not be verified in our study inhealthy subjects.

The use of nitrous oxide to reduce gagging re-quires special equipment in the practice, and it is wellknown that inhalation sedation alleviates dental anx-iety and reduces dental pain.13 On the other hand, thedentist phobia syndrome, with the exaggerated gag-ging pathologic reflex, is the symptom of different psy-chopathologic processes such as specific fear, re-pugnance/fear-based disturbances, diffuse anxiety,goal-directed behavior, depressive states, and vis-ceral pathology.14 It is therefore most probable thatthe relief of anxiety by inhalation sedation can alsodecrease gagging. In comparing the effects of usingnitrous oxide when stimulating the soft palate (group3) to stimulation with the spoon alone (group 1) orstimulation with spoon and table salt (group 2), thedifferences were highly significant (P < 0.001), mean-ing that nitrous oxide is highly effective in reducingthe gag reflex. These results are in line with com-monly accepted statements.13

However, the table salt method may have a psy-chologic effect on patients with the dentist phobiasyndrome. It would seem interesting to do further re-search on these patients and to include another groupof patients with gagging problems. Within the limitsof the study, table salt did not seem to extend the timeto triggering the gag reflex in a normal healthy pop-ulation, whereas nitrous oxide had a significant effect.

References

1. Leder SB. Gag reflex and dysphagia. Head Neck 1996;18:138141.

2. Watt DM, MacGregor AR. Designing Complete Dentures, ed 2.Bristol: Wright, 1986:154.

3. Hattab FN, Al-Omari MA, Al-Duwayri ZN. Management of a pa-tients gag reflex in making an irreversible hydrocolloid im-pression. J Prosthet Dent 1999;81:369.

4. Murphy PJ, Erskine R, Langton JA. The effect of intravenously ad-ministered diazepam, midazolam and flumazenil on the sensi-tivity of upper airway reflexes. Anaesthesia 1994;49:105110.

Table 1 Time (s) for Eliciting Gag Reflex Using ThreeDifferent Techniques

StandardEvent Mean deviation Range

1 7.7 3.7 313.52 8.9 3.5 2.413.53 24.0 9.6 6.734.0

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Volume 14, Number 4, 2001The International Journal of Prosthodontics 366

Chidiac et alGagging Prevention Using Nitrous Oxide or Salt

5. Langa H. Relative analgesia in dental practice. Inhalation anal-gesia and sedation with nitrous oxide. Philadelphia: WBSaunders, 1976:245246.

6. Muir JD, Calvert EJ. Vomiting during the taking of dental im-pressions. Two case reports of the use of psychological tech-niques. Br Dent J 1988;165:139141.

7. Barsby MJ. The use of hypnosis in the management of gaggingand intolerance to dentures. Br Dent J 1994;176:97102.

8. Saunders RM, Cameron J. Psychogenic gagging: Identificationand treatment recommendations. Compend Contin Educ Dent1997;18:430438.

9. Callison GM. A modified edentulous maxillary custom tray tohelp prevent gagging. J Prosthet Dent 1989;62:4850.

10. Ren X. Making an impression of a maxillary edentulous patientwith gag reflex by pressing caves. J Prosthet Dent 1997;78:533.

11. Fiske J. The role of acupuncture in controlling the gagging re-flexA report based on 10 cases. Presented at the EuropeanProsthodontic Associations 24th Annual Conference,Groningen, The Netherlands, 2326 August 2000.

12. Friedman MH, Weintraub MI. Temporary elimination of gag re-flex for dental procedures. J Prosthet Dent 1995;73:319.

13. Holroyd I, Roberts GJ. Inhalation sedation with nitrous oxide: Areview. Dent Update 2000;27:141146.

14. Schroeder HE, Schroeder U, Santibanez-H G. Dentist phobia.Pavlov J Biol Sci 1986;21:1624.

Literature Abstract

Early implant failures in patients treated with Brnemark system titanium dentalimplants: A retrospective study.

The aim of this study was to identify various explanatory factors associated with early titaniumimplant failure. All 43 patients with failing and nonosseointegrated implants at the stage twosurgery during the years 1992 to 1997 at a Swedish implant center were invited to participate.Three patients declined participation, resulting in a sample size of 40 subjects. A gender- andage-matched control group of 40 subjects with long-term successfully integrated implants wasidentified and included. All generally used variables, including bone quantity and quality, werenoted. In addition, a venous blood sample was collected from the participants for analyses ofantibody avidity scores for Bacteroides forsythus and antibody titer to Streptococcus aureus. Amultivariate regression analysis with implant outcome as the dependent variable revealedhighly significant associations with both the avidity scores for B forsythus (P < .0001) and theantibody titer to S aureus (P < .001), and a significant association with the bone shape and re-sorption (BDR) score (P < .05), but not with other variables such as bone quality score, initialimplant stability, etc. The authors conclude that immunologic factors are involved in osseointe-gration. The result of the present study may, in this reviewers opinion, even open up a para-digm shift in the understanding of early implant failures.

Kronstrm M, Svenson B, Hallman M, Persson GR. Int J Oral Maxillofac Implants 2001;16:201207.References: 37. Reprints: Dr Mats Kronstrm, Department of Prosthetic Dentistry, Central Hospital,. SE-54185 Skvde, Sweden. e-mail: mats.kronstrom@vgregion.seSP

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