Respiratory tract infections and concomitant pericoronitis of the wisdom teeth

BMJ 1995; 310 doi: (Published 01 April 1995) Cite this as: BMJ 1995;310:834
  1. Jukka H Meurman, professora,
  2. Ari Rajasuo, majorb,
  3. Heikki Murtomaa, associate professorc,
  4. Seppo Savolainen, majord
  1. a Faculty of Dentistry, University of Kuopio, PO Box 1627, 70211 Kuopio, Finland
  2. b Valkeala Military Hospital, Valkeala, Finland
  3. c Institute of Dentistry, University of Helsinki, Helsinki, Finland
  4. d Central Military Hospital, Helsinki, Finland
  1. Correspondence to: Professor Meurman.
  • Accepted 17 February 1995


Objective: To discover if there is an association between respiratory tract infections and pericoronitis of erupting third molars in young adults.

Design: Data from male military conscripts' medical records were collected over five years and the incidence of respiratory tract infection before and after acute pericoronitis (191 cases) and before and after standard (722 cases) and operative (741) extractions compared with that in controls (n = 703) who had no infections in the third molar regions.

Subjects: 14500 male military conscripts aged 20.

Setting: Garrisons in Valkeala and Kouvola, Finland.

Results: The incidence of respiratory tract infection was significantly higher during the two weeks before acute pericoronitis was diagnosed compared with that in controls. The highest incidence was observed in the three days before pericoronitis (odds ratio 6.8; 95% confidence interval 3.0 to 15.0). The incidence was also increased in the first week after pericoronitis (odds ratio 3.7; 1.6 to 8.4) and three days before (odds ratio 2.6; 0.9 to 7.5) and during the first week after extraction of third molars (odds ratio 2.6; 1.3 to 5.3).

Conclusions: Respiratory tract infection may precipitate and occur concomitantly with acute pericoronitis. Third molar surgery for pericoronitis, on the other hand, may trigger respiratory tract infection.

Key messages

  • Key messages

  • A possible link between respiratory tract infections and pericoronitis of the wisdom teeth has not been studied before

  • Respiratory tract infection and pericoronitis seem to occur concomitantly

  • Partly erupted wisdom teeth which are unlikely to erupt should be extracted before pericoronitis develops and to avoid a possible episode of respiratory tract infection


Adults in industrialised countries have two to four episodes of respiratory tract infections a year.1 2 3 Pharyngitis and tonsillitis are common.4 Over 40 million patients a year go to their doctors for sore throat in the United States alone.5 In Finland in 1992, 40 500 cases of respiratory tract infection were recorded in 22 000 male military conscripts during national service lasting 8-11 months.6 Acute pericoronitis of partly erupted third molars is the commonest7 or second commonest8 9 acute dental problem in army personnel, characteristically affecting 20 to 25 year olds.10 11 Mandibular third molars, which may never erupt completely,12 are affected in at least 95% of cases.10 13

Reportedly, pericoronitis of mandibular third molars may be associated with respiratory tract infection, emotional and physical stress, and excessive physical fatigue.10 14 This has not been studied formally, however, and we sought to determine if there was an association between respiratory tract infection and acute pericoronitis in conscripts of the Finnish defence forces.

Subjects and methods

The sample consisted of 14 500 Finnish male conscripts in the Valkeala and Kouvola garrisons from 1986 to 1990. Each conscript served 8-11 months. On average 2700 national service conscripts were based in the two garrisons at any time.

One thousand six hundred and ninety two conscripts underwent treatment or exploration of their third molars. Data on 182 subjects (11%) were not available because records were missing at the time of study. Data were ultimately collected from 1510 conscripts, who attended on 3710 occasions for third molar related problems at the dental units of the two military hospitals. The mean age of the patients was 20.5 (SD 1.2) years (range 17.5-29.7).

Details of upper and lower respiratory tract infections were extracted from patient records one month before and two weeks after acute pericoronitis and one month before and one month after third molar extractions. Respiratory tract infection was diagnosed by army physicians and classified according to the International Classification of Diseases15 as pharyngitis, nasopharyngitis, tonsillitis, otitis, sinusitis, unspecified upper respiratory tract infection, laryngitis, tracheitis, bronchitis, or pneumonia.

Acute pericoronitis and extractions of third molars were recorded by army dentists. The first study group comprised all cases of acute pericoronitis (191 patients; 183 (96%) with pericoronitis of lower third molars) requiring antibiotics (92; 48%), other drugs, or antiseptic mouthwashes. Patients who were symptom free or who had more diffuse, chronic pericoronitis were not included. The second study group comprised all cases of standard (722) or operative (741) extractions of third molars; a total of 1881 teeth were extracted. Removal of upper third molars accounted for 491 (68%) standard extractions. Lower third molars accounted for 704 (95%) operative extractions, defined as removals that required a gingival flap to be raised and the alveolar socket to be sutured. In 422 (57%) operative extractions tooth sectioning or bone removal with surgical drills was also required.

The incidence of respiratory tract infection before acute pericoronitis was compared with that in 703 controls with abnormal position or caries as their only diagnosis relating to third molars.

The incidence of respiratory tract infection after acute pericoronitis and before and after extraction of third molars was compared with that among the same controls. Respiratory tract infection was recorded only once if patients were examined several times in one week. When medical appointments were more than seven days apart diagnoses were recorded separately. Third molar extractions were recorded only once if teeth were extracted in two appointments in one week. Periods for recording respiratory tract infection before and after acute pericoronitis episodes and before and after extractions were three days, one week, two weeks, and three to four weeks.

Statistical analysis—Odds ratios with 95% confidence intervals relating to incidences of respiratory tract infection were calculated for study groups and controls. In addition, Fisher's exact test was used in comparisons between study groups and controls. P values of <0.05 were taken as significant. The SAS statistical package was used.


Thirty two (17%) patients in the first study group had a respiratory tract infection during 14 days before acute pericoronitis versus 44 (6.3%) controls (P<0.001). During the preceding seven days numbers with infection were 22 (12%) patients versus 29 (4.1%) controls (P<0.001), and in the three days before pericoronitis 17 (8.9%) patients versus 10 (1.4%) controls (P<0.001). Increased incidences were also found when cases of tonsillitis and pharyngitis were combined during two weeks, one week, and three days before diagnosis of acute pericoronitis. Significantly more cases of respiratory tract infection were diagnosed in the first study group during the first week after pericoronitis than in controls (18 (9.4%) patients versus 19 (2.7%) controls; P=0.002). Odds ratios relating to the incidence of respiratory tract infection in the study and control groups are given in the table, with all respiratory tract infections and episodes of tonsillitis and pharyngitis listed separately.

Risk of respiratory tract infections in subjects with and without third molar related problems. Results expressed as odds ratios and confidence intervals with respect to time before and after diagnosis of pericoronitis or extraction of third molars

View this table:

In the three days before the 722 standard extractions the incidence of respiratory tract infection was 3.0% (22 cases) whereas that among controls was 1.3% (nine) (NS). During the first week after extractions the incidence of infection increased to 6.8% (49 patients) versus 2.7% (19 controls) (P=0.008). Before and after the 741 operative extractions, however, the incidence of respiratory tract infection was not significantly greater in the study group (3.4% (25 cases before, 3.1% (23) after the one week observation period)) than in controls (4.0% (28 cases before, 2.7% (19) after)).


Our results show that respiratory tract infection may indeed trigger acute pericoronitis. Plainly the risk of pericoronitis is increased if patients are weakened by respiratory tract infection. Whether the reverse is true is a matter for debate. In this study the incidence of respiratory tract infection was also greater in the first week after acute pericoronitis.

Our findings also show that third molar extractions can trigger respiratory tract infection. In addition, we observed an increased incidence of respiratory tract infection in the three days before standard extractions (second study group). This can partly be explained by existing pericoronitis, many such infections of the lower third molars being treated by extraction of the respective upper third molars in order to avoid their traumatising the pericoronitis site.16 The incidence of respiratory tract infection was not significantly correlated with operative extractions but was significantly correlated with standard extractions. This could be explained by the frequent use of antibiotics in operative extractions in Finland to prevent postoperative discomfort.17 In this series antibiotics were prescribed postoperatively in 90% (667) operative extractions but in only 5% (36) of standard extractions.

Most respiratory tract infections are viral. Degre suggested that viral infections may damage mucous membranes and predispose tissues to secondary invasion or superinfection by bacteria.18 Associations between respiratory tract infection, acute pericoronitis, and extractions of third molars can be considered mainly on a bacteriological basis, the virology of pericoronitis being unknown. It has been suggested that Gram negative anaerobic microorganisms such as spirochetes, fusobacteria, Prevotella intermedia, Actinobacillus actinomycetemcomitans, Peptostreptococcus micros, and Veillonella species13 19 20 21 may be incriminated in pericoronitis. Many aerobic and anaerobic organisms have also been found in alveolar bone sockets after extraction of teeth.22

The proximity of the nasopharynx to the third molars favours the hypothesis that they may have common pathogenic aspects. Thus we analysed cases of tonsillitis and pharyngitis separately. In the time intervals studied both before and after pericoronotis was diagnosed the risk of tonsillitis and pharyngitis was in some cases greater than when all respiratory tract infections were taken into account. Unpublished data show that the tonsils and lower third molar regions harbour similar anaerobic bacterial species. These may play a part both in pericoronitis and in tonsillitis. Anaerobes have been linked particularly with recurrent tonsillitis in children.23

A five month to one year cyclical recurrence is typical of acute pericoronitis when the affected tooth is not extracted after the first episode.10 The cycle can be explained by the recurrence pattern of respiratory tract infection. All partly erupted third molars are at risk of acute pericoronitis,12 and it is generally accepted that a weakened general condition increases the risk. Based on our findings we emphasise the particular role of sore throat in triggering pericoronitis. In clinical military practice young soldiers commonly have acute pericoronitis and tonsillopharyngitis simultaneously. Many such patients say that their sore throat followed prolonged tenderness in a lower third molar region. These cases together with our results emphasise the need for rethinking: pericoronitis may also precede respiratory tract infection. Furthermore, when a tooth affected by pericoronitis is extracted an episode of respiratory tract infection may follow.

This work was supported by the Health Care Section of the Defence Staff of the Finnish Defence Forces and by a grant from the Finnish Dental Association.


  1. 1.
  2. 2.
  3. 3.
  4. 4.
  5. 5.
  6. 6.
  7. 7.
  8. 8.
  9. 9.
  10. 10.
  11. 11.
  12. 12.
  13. 13.
  14. 14.
  15. 15.
  16. 16.
  17. 17.
  18. 18.
  19. 19.
  20. 20.
  21. 21.
  22. 22.
  23. 23.
View Abstract