Australian Dental Journal 2002;47:2. 131

Mandibular fracture patterns in Tasmania, Australia

P Dongas*, GM Hall*

AbstractBackground: No previous studies on mandibularfracture patterns in Tasmania, and very fewelsewhere in Australia, have undertaken to discoverwhich identified age, gender, aetiology, anatomicallocation of the fracture, period of injury, whetheralcohol consumption was associated with the injury,and treatment of mandibular fractures.Method: A retrospective study was undertaken of251 patients with fractured mandibles presenting tothe Royal Hobart Hospital, Tasmania from 1993-1999. Data were obtained from the Oral andMaxillofacial Surgery unit fracture record bookscross-checked with patients, impatient/outpatienthospital records.Results: The male to female ratio was 4.5:1, withmandibular fractures most common in the male agegroup of 21-30 years. Assaults (55 per cent of allpatients) were the major cause of fractures. Malesaccounted for 85.5 per cent of assaults, withpunching being the most common method, followedby motor vehicle accidents (MVA), 18.3 per cent andsport, 16.7 per cent. In sport, Australian RulesFootball was the most common cause, accountingfor 45.2 per cent of sporting injuries. The site mostfrequently fractured was the angle of the mandible.Alcohol abuse was seen in 41.4 per cent of thepatients with 84.6 per cent being male. Openreduction and internal fixation with miniplateosteosynthesis, was the preferred treatmentmodality. The results are compared with other series.Conclusions: Mandibular fractures are common inTasmania, with the highest rates involved in assaultsand sport (especially Australian Rules Football) anda low rate in MVA. These fractures commonlyoccurred in young males in which assaults, alcoholand social issues were associated. Therefore,preventive measures and strong public awarenessaddressing this group may be of benefit in reducingthe rate of assaults and sporting injuries to themandible.

Key words: Mandibular fracture, aetiology, alcohol, facialtrauma.

(Accepted for publication 20 December 2000.)

INTRODUCTIONThe facial area is one of the most frequently injured

areas of the body,1-4 and the mandible is one of the mostcommon maxillofacial bones fractured,1,5,6 due to itsprominent position on the face.

Studies around the world have shown that assaultsare the predominant cause of maxillofacial fractures indeveloped countries, while motor vehicle accidents(MVA) are the most common cause in developingcountries.2,7-13

Aetiology varies from country to country and theycan usually be attributed to cultural, social,environmental and economical factors. The relationshipbetween alcohol consumption and maxillofacialinjuries is well known.1,6,10,14,15

Treatment of mandibular fractures has changed overthe last 20 years in Western societies. There has been adecrease in the use of wire osteosynthesis and inter-maxillary fixation and an increase in preference foropen reduction and internal fixation with miniplates.15,16

This has helped reduce malocclusion, non-union,improved mouth opening, speech and oral hygiene,decreased weight loss and increased the ability forpatients to return to work earlier.15,17

Limited information is available regardingmandibular fracture patterns in Australia, and noprevious study has been undertaken in Tasmania,Australia. The aim of the study was to examine theincidence, aetiology, age, gender, anatomical distribution,consumption of alcohol prior to trauma, and treatmentof mandibular fractures presenting to the Royal HobartHospital, Tasmania, Australia, and to compare thesewith other studies. The results may aid in identifyingaetiological factors and in planning strategies forprevention.

MATERIALS AND METHODSA retrospective study of all mandibular fractures seen

at the Royal Hobart Hospital from January 1993 toAugust 1999 inclusive, was undertaken. Data for eachpatient were obtained from the Oral and MaxillofacialSurgery Unit fracture record books. The data werecross checked by reviewing each patient’s hospitalinpatient/outpatient records. The data obtainedincluded: age, gender, yearly/monthly fracture

*Oral and Maxillofacial Surgery Unit, Royal Hobart Hospital, The University of Tasmania.

S C I E N T I F I C A R T I C L EAustralian Dental Journal 2002;47:(2):131-137

distribution, aetiology, anatomical fracture site,alcohol/drug association and treatment.

RESULTSDuring the seven-year period (1993-1999) a total of

251 patients had sustained 385 mandibular fractures.The average number of patients (with mandibularfractures) that presented annually to the departmentwas 35.9, and the annual average of mandibular frac-tures was 55.

Age and gender distributionPatients with mandibular fractures ranged in age

from a 2-year-old male involved in a MVA, to an 87-year-old female who was a victim of an assault. Therewere 205 males and 46 females accounting for the totalof 251 patients, with a male to female ratio of 4.5:1.The majority of mandibular fractures for both malesand females occurred in the age group of 21-30 years(34.7 per cent – 87 patients), and the most frequent agewas 21 years (Table 1).

Yearly and monthly distributionThe total number of mandibular fractures per year

was constant, with the highest incidence in 1996(Fig 1). The monthly distribution showed January tohave the highest incidence, followed closely by May.The lowest incidence was November (Fig 2).

Aetiology of mandibular fracturesThe most common cause of mandibular fractures

was assault (55 per cent), followed by MVA (18.3 per

cent) and sport (16.7 per cent): see Table 2. Of thepatients involved in alleged assaults, 85.5 per cent weremale and 14.5 per cent were female. There were 68.8per cent males and 11.6 per cent females involved inalleged punch(es). The assault breakdown is shown inTable 3. The alleged assaults occurred in bar fights (themost common place), home or public places, domesticdisputes, parties, and home invasion.

Of the patients involved in MVA, 73.9 per cent weremale and 26.1 per cent female. A total of 50 per cent ofthe MVA victims, were involved in an automobileaccident (Table 3). Of the patients involved in sport,83.3 per cent were male and 16.7 per cent were female.Australian Rules Football was the predominantsporting activity, in which 45.2 per cent males and nofemales sustained fractured mandibles. (The entiresport breakdown is shown in Table 3.) Other causes ofmandibular fractures are listed in Table 2.

In 25 (10 per cent) of the total patients (251), themandibular fractures were associated with mid-facialfractures, and 226 patients (90 per cent) involved onlythe mandible. Of the mandibular fractures alsoinvolving the mid-facial area, MVA had the highestincidence of 52 per cent, 44 per cent were caused byassaults and 4 per cent by a fall. No associated mid-facial fractures occurred in the other categories ofaetiology.

Anatomical location of mandibular fracturesIn 251 patients, the total number of mandibular

fractures was 385, with an average of 1.53 fractures permandible. The angle was the most commonly involved

132 Australian Dental Journal 2002;47:2.

Table 1. Age and gender distributionAge (yrs) Male Female Total (%)

0-10 6 2 8 (3.2)11-20 63 11 74 (29.5)21-30 72 15 87 (34.7)31-40 39 7 46 (18.3)41-50 14 4 18 (7.2)51-60 8 2 10 (3.9)≥61 3 5 8 (3.2)

Total 205 (81.7) 46 (18.3) 251 (100)

Table 2. Aetiology of mandibular fracturesAetiology No. of fractures (%)

Assault 138 (55.0)MVA 46 (18.3)Sport 42 (16.7)Fall 13 (5.2)Fit 7 (2.8)Industrial 3 (1.2)Gunshot 1 (0.4)Oral surgery 1 (0.4)Total 251 (100)Fig 1. Yearly distribution.

Fig 2. Monthly distribution.

Num

ber

of p

atie

nts

Num

ber

of p

atie

nts

Month

Jan

Feb

Mar

Apr

May Jun

Jul

Aug

Sep Oct

Nov

Dec

40

35

30

25

20

15

10

5

0

36

19

25 23

32

2116

19

14 1511

20

50

40

30

20

10

0

3540 39

46

3531

25

1993 1994 1995 1996 1997 1998 1999

Year

Australian Dental Journal 2002;47:2. 133

area with 32 per cent of the total fractures. This wasfollowed by the subcondyle region 23.3 per cent, body17.7 per cent and the parasymphysis 15.6 per cent. Theremaining fractures each accounted for less than 4 percent of the total fractures (Fig 3).

There was no significant difference between the rightside (48.8 per cent) and the left side (51.2 per cent) ofthe mandible. The mandible had a single fracture in 53per cent of the patients, 40.6 per cent had twofractures, 4.8 per cent three fractures, and 0.8 per centhad greater than three fractures.

Mandibular fracture pattern combinationsTable 4 shows that of the 138 patients assaulted, the

most common single fracture occurred in the angle ofthe mandible in 47 patients (34 per cent). With regardsto MVA (46 patients), a single fracture in the body ofthe mandible was the most frequently affected site

occurring in six patients (13 per cent). Sport relatedinjuries (42 patients) also resulted in the angle of themandible to fracture in 12 patients (28.6 per cent). Fallsand fits (20 patients) most often caused the subcondyleregion to fracture in seven patients (35 per cent).

There were 31 different mandibular fracturecombinations involving more than one fracture. Themost common pattern combinations were angle/parasymphysis (8 per cent), followed by body/angle(7.2 per cent), subcondyle/parasymphysis (6.4 per cent)and subcondyle/body (4 per cent). Of the patientsassaulted, the body/angle (10.1 per cent) was thepredominant combination, followed by the angle/parasymphysis (8.7 per cent) and the subcondyle/parasymphysis (7.2 per cent).

Of the patients involved in sport the angle/parasymphysis (11.9 per cent) was the most commoncombination. Sports usually resulted in single fracturesof the mandible, whilst MVA patients were dispersedover all the different combinations and single fractures.

Alcohol consumptionA total of 104 patients with mandibular fractures

(41.4 per cent) were documented as being under theinfluence of alcohol on presentation to the RoyalHobart Hospital as shown in Table 5. Alcoholconsumption was more commonly associated withmales sustaining more mandibular fractures thanfemales (84.6 per cent were male and 15.4 per centfemale).

Of all the patients that were under the influence ofalcohol, 79.8 per cent were assault victims in which the

Table 3. Male/Female in aetiological categoriesAetiology Male Female Total (%)

Assaultpunch 95 (68.8) 16 (11.6) 111 (80.4)kick 15 (10.9) 1 (0.7) 16 (11.6)punch/kick 6 0 6other 2 3 5

Total 118 (85.5) 20 (14.5) 138 (100)

MVAautomobile 14 (30.4) 9 (19.6) 23 (50.0)bicycle 10 (21.7) 2 (4.3) 12 (26.0)motorcycle 9 (19.6) 0 9 (19.6)pedestrian 1 1 2

Total 34 (73.9) 12 (26.1) 46 (100)

Sportfootball 19 (45.2) 0 19 (45.2)cricket 5 (11.9) 2 (4.8) 7 (16.7)horse riding 2 (4.8) 2 (4.8) 4 (9.6)soccer 3 (7.1) 0 3 (7.1)golf 2 1 3hockey 2 1 3bungee jumping 1 0 1roller blading 0 1 1netball 1 0 1

Total 35 (83.3) 7 (16.7) 42 (100)

Fall 8 (61.5) 5 (38.5) 13 (100)Fit 6 (85.7) 1 (14.3) 7 (100)Industrial 3 0 3Gun shot 1 0 1Oral surgery 0 1 1

Table 4. Mandibular fracture pattern combinations and aetiologyAssault MVA Sport Other Total (%)

Single fracturesubcondyle 13 1 7 8 29 (11.6)angle 47 (34.0) 3 12 (28.6) 3 65 (25.9)body 9 6 (13.0) 4 1 20parasymphysis 4 4 2 10

Combination fracturebody/angle 14 (10.1) 2 2 18 (7.2)angle/parasymphysis 12 (8.7) 2 5 (11.9) 1 20 (8.0)subcondyle/body 7 2 1 10 (4.0)subcondyle/parasymphysis 10 (7.2) 3 2 1 16 (6.4)

Other 22 23 7 12 64

Total 138 46 42 25 251

Fig 3. Anatomical location of mandibular fractures.

Condyle

Coronoid

Alveolus 2.1%

0.8%

23.3%

1.8%

32.0%

17.7%

15.6%

1.5%

Ramus

Angle

Body

ParasymphysisSymphysis 3.6%

Subcondyle

most common age group was 21-30 years (37.3 percent). Those that were involved in a MVA (11.5 percent), were aged between 31-40 years (33.3 per cent).Overall the most common age group in which alcoholconsumption was involved resulting in a fracturedmandible was 21-30 years of age (Table 6).

It is important to note that these figures did not takeinto account alcohol consumption by assailants andnon-patient motor vehicle drivers/passengers, and onlytook into account alcohol use by persons sustaining afractured mandible.

Drug useThe study showed that 4.4 per cent of patients with

mandibular fractures involved illicit drug use. This figureis undoubtedly underestimated as the hospital recordsusually do not disclose these details, as patients are oftenreluctant to openly reveal such information andclinicians rarely investigate drug use in every patient.

Treatment of mandibular fracturesThe majority of patients with mandibular fractures

(251) were treated by open reduction and internal fixa-tion (ORIF) with miniplates (41.4 per cent). There were25.9 per cent whom also had ORIF, followed by post-operative intermaxillary fixation (IMF). These patientshad multiple fractures and in most cases it involved thesubcondyle region. Conservative treatment (19.1 percent) usually involved a soft diet, analgesia, ±diazepam, ± antibiotics, and the patient was regularlyobserved over a six week period.

Closed reduction was the treatment of least choice in13.6 per cent of the patients, this involved a nonsurgical approach of IMF, using eyelet wires or archbars and wire or elastics for four to six weeks.

DISCUSSIONThe Oral and Maxillofacial Unit of the Royal Hobart

Hospital serves a population of 470,45718 treating allthe mandibular fractures presenting or referred to thehospital.

Age and gender distributionIn this study, males accounted for 81.7 per cent of all

patients with mandibular fractures, similar to thatreported by Edwards et al. (80 per cent),1 Fridrich et al.(78 per cent)19 and by Asadi et al. (79 per cent).20 Themale to female ratio of 4.5:1, is consistent with studiesby Allan and Daly5 in Newcastle, Australia andEdwards et al.1 in Adelaide, Australia. This is slightlymore than the majority of mandibular fracture studies

around the world, which had a male to female ratio ofapproximately 3:1.3,6,19, 21-23

The highest incidence of mandibular fracturesoccurred in patients who were 21-30 years of age inboth males and females, with males making up themajority in this group. This is consistent with findingsof previously published work.3,23

It is well documented that males are more likely to beinvolved in violent conduct, participate in contactsport, and drive recklessly, making them moresusceptible to trauma.3,10,11,24 Therefore, it is notsurprising that males outnumber females in this study.

Yearly and monthly distributionThe total number of mandibular fractures was

moderately constant from year to year, with approxi-mately 35 patients per year, with the exception of 1996,which had 46 and 1999 with 25 (the study finished atthe end of August).

More fractures occurred in January than any othermonth – these mainly occurred in early January, whenthe New Years eve/day celebrations take place. Januaryin Australia is also the middle of summer, whenoutdoor activities and festivities are attended by largecrowds. Mandibular fractures also prevailed in themonth of May, which coincides with thecommencement of winter contact sports, especiallyAustralian Rules Football.

Aetiology of mandibular fracturesThis study found assaults (55 per cent) to be the

predominant cause of mandibular fractures, followedby MVA (18.3 per cent), sport (16.7 per cent) and falls(5.2 per cent). These findings were similar to thosefound by Edwards et al.,1 Adi et al.21 and Ellis et al.22

The assault rates reported by Rix et al. (72.5 percent) in Sydney, Australia15 and Asadi et al. (74 percent) in Manchester, United Kingdom,20 are two of thehighest reported. Both stated that the effects of socialbehaviour and alcohol, complicated by everydaystresses of residing in large city areas are associatedwith the increase in interpersonal violence.

An earlier study by Larsen et al.23 in Denmarkshowed that MVA (57 per cent) were the most commoncause of mandibular fractures, and that assaultsaccounted for 16 per cent. Reports from Sweden, in

134 Australian Dental Journal 2002;47:2.

Table 5. Involvement of alcohol by sexMale Female Total (%)

Alcohol 88 (84.6) 16 (15.4) 104 (41.4)No alcohol 117 30 147

Total 205 46 251

Table 6. Age, alcohol and aetiology

Age(yrs) Assault MVA Other Total (%)+alcohol +alcohol +alcohol

0-1011-20 21 (25.3) 2 (16.7) 2 25 (24.0)21-30 31 (37.3) 3 (25.0) 2 36 (34.6)31-40 21 (25.3) 4 (33.3) 25 (24.0)41-50 6 1 3 1051-60 4 1 561+ 2 1 3

Total 83 (79.8) 12 (11.5) 9 (8.7) 104 (100)

Australian Dental Journal 2002;47:2. 135

1987 by Erikson et al.9 demonstrated that in the periods1952-1962 and 1975-1985 assaults increased from 26 to 44 per cent, and MVA decreased from 41 to 22 per cent respectively (the mandible was involved inapproximately 83 per cent of jaw fractures). Theyaccounted for the increase in assaults by stating thatthere was an increase in violence, and that thecompulsory use of seat belts explained the decrease inMVA trauma.9 Therefore, in earlier studies MVAseemed to be the most common cause of mandibularfractures. However, recent reports show that assaultsare predominating, as indicated by this study.

Our study also revealed that in assaults, mandibularfractures occurred in 85.5 per cent males and 14.5 percent females. In both males and females punching wasidentified as the predominant cause of mandibularfractures as reported.25

In MVA trauma, 73.9 per cent were male and 26.1per cent female. As reported in other studies themajority of MVA involved an automobile in both males(30.4 per cent) and females (19.6 per cent) cases.2,19 Itwas interesting to note that bicycle trauma (26 per cent)was the second most common cause of MVA resultingin mandibular fractures, with males sustaining injuriesmore frequently than females, at 21.7 per cent. Bicycleriding is not a common mode of transport in Tasmania.However, bicycle riding proved to be more common incausing mandibular fractures than motorcycle accidents.Perhaps bicycle helmets (which are currently worn inTasmania) would benefit from some form of facialcoverage similar to that of a motorcycle helmet.

The percentage of fractures sustained during sportswas 16.7 per cent, this was in agreement with thatreported by Edwards et al. (13 per cent)1 and Allan andDaly (19 per cent).5 In Tasmania, Australian RulesFootball was strongly associated with mandibularfractures accounting for 45.2 per cent of all sports andthe entire population was male. Australian RulesFootball has a high participation rate in Tasmania, andit is also a contact sport in which the male populationpredominantly play. The Newcastle study by Allan andDaly, reported that Rugby was the most popular sportcontributing to mandibular fractures.5 This reflects thepopularity of Rugby in the state of New South Wales,Australia. Lim et al.,26 from Adelaide reported thatAustralian Rules Football was accountable for 52.6 percent of the facial fractures.

Only 10 per cent of patients with mandibularfractures had an associated mid-facial fracture. Themajority, 90 per cent had only mandibular fractures.MVA were the predominant cause of mandibularfractures associated with a mid-facial fracture, as seenin other studies.21,23

Anatomical locationThe most common site for mandibular fractures in

the Tasmanian community was the angle of themandible, which is consistent with other studies,1,2,19,20,23

followed by the condyle region, then the body of the

mandible. These findings are consistent with the studyby Hammond et al., in Otago, New Zealand.2

However, these results are in contrast with studies inNigeria by Oji, in Enugu,11 and Abiose in Ibadan,7

where the mandibular body was identified as the mostcommon fracture site. In all these studies MVA werereported to be the leading contributing factors to facialfractures. Fractures of the body of the mandible werealso common in Scotland where assaults are reported asthe major cause.21,22 These observations show that indeveloped countries the angle or body is the mostcommon place for the mandible to fracture in allegedassaults, and in developing countries the body is thepredominant position resulting from MVA.

In Tasmania, the angle of the mandible sustainedfractures more frequently from injuries involvingassaults and sport activities. This is not surprising asthis site is commonly weakened by the uneruptedwisdom teeth.2

The most common mandibular fracture combinationsin this study were angle/parasymphysis followed closelyby angle/body. These often occurred as a result ofassaults, with the mandible presumably fracturing inareas deficient in strength. This is in contrast to thestudy by Abiose, in which the body bilaterally wasreported as the most frequent mandibular fracturecombination.7 However, MVA presented to be the mostcommon cause in that study, not assaults.

Alcohol consumptionAlcohol consumption is a well known contributing

factor to mandibular fractures derived fromassaults.1,6,14,15 This study showed that 41.4 per cent ofpatients with mandibular fractures were under theinfluence of alcohol when initially assessed at the RoyalHobart Hospital. Similar figures were shown byOikarinen et al. in Oula, Finland, with 44 per cent ofthe patients with mandibular fractures under theinfluence of alcohol at their first visit to the emergencyunit,14 and Renton and Wiesenfeld in Melbourne,Australia with 40 per cent of patients having consumedalcohol.16 A higher figure was reported by Rix et al. inSydney, Australia, with alcohol implicated in 58 percent of the patients with mandibular fractures.15 Theyhad reported one of the highest assault rates of 72.5 percent (previously reported).

Limitations exist in both retrospective and prospectivestudies of alcohol consumption. With retrospectivestudies it is difficult to retrieve from case notes theexact figure. Different clinicians record alcoholintoxication in different areas of the patient records (asin the present study), and some may not record it at all.Thus, the Tasmanian alcohol consumption figure maybe underestimated.

In prospective studies, actual figures may be under-estimated also, as identifying alcohol consumption inassailants and non-patients, not suffering from afractured mandible would be difficult, as they do notalways present with the victim. Finally, there is usually

a delay in seeking management of the fracturedmandible if the trauma took place under the influenceof alcohol.6

In both retrospective and prospective studies alcoholbreath and blood testing each patient presenting with afractured mandible would be difficult but possible withethics and council approval for patient protection. Inthis study only one patient was alcohol blood andbreath tested (by a police officer) as he was a MVAvictim.

It is interesting to note that Oikarinen et al.,6

commented on a study in the United Kingdom andFrance, undertaken by Timoney et al.,27 which reportedthat alcohol was more likely to be a contributing factorin assaults in the United Kingdom than France, eventhough France had a higher alcohol consumption rateper capita than the United Kingdom. Oikarinen et al.concluded that alcohol consumption and facial traumaare related to other issues such as social problems andage of the patient. Telfer et al. claimed a relationshipbetween facial bone fractures in assaults with alcoholand unemployment.12

Our study showed that assaults resulting inmandibular fractures occurred in cases where alcoholconsumption was at its highest (79.8 per cent), andpredominantly amongst young males (21-30yrs).Tasmania has the highest male unemployment rate(10.4 per cent) in the nation, compared to theAustralian rate of 7.5 per cent.18 The unemploymentrate in this sample of mandibular fractures could not beverified, as the medical records were incomplete.However, the relationship between assault, alcoholconsumption, unemployment and young males,complicated by complex social issues, undoubtedlyexists and it is not only a direct relationship betweenalcohol and assaults.

Treatment of mandibular fracturesIn recent years there has been a trend towards ORIF

as the choice of treatment of mandibular fractures.1,2,13,15

Tasmania was no different, with ORIF being thetreatment of choice, in this study.

CONCLUSIONIn Tasmania, Australia, fractures of the mandible are

common. There is a low rate of mandibular fracturesassociated with MVA, probably due to public aware-ness of strict traffic laws, for example; compulsorywearing of seatbelts, random alcohol breath testing andspeed limits. Unfortunately, there was a higher thanexpected rate amongst bicycle riders, a helmet withfacial coverage similar to that of a motor cycle helmetwould perhaps be beneficial.

A high rate of mandibular fractures were sustainedby patients involved in assaults and sport (especiallyAustralian Rules Football). These fractures werecommon amongst young males with whom assaults,alcohol and social issues seemed to be associated.

Therefore, it is suggestive that preventive measuresaddressing this group with regards to the association ofinterpersonal violence and alcohol abuse withmandibular fractures, may be of benefit. However,social problems may be difficult to address as theyinvolve complex issues for example, family background,and personality types.

In regards to Australian Rules Football thecompulsory wearing of head gear, mouthguards andpossibly looking at rule and regulation changes could beuseful. Both aetiologies would benefit from strong publicawareness if there is to be a reduction in the increasingrate of assaults and sporting injuries to the mandible.

ACKNOWLEDGMENTSThe authors would like to thank the staff of the

medical records department, Royal Hobart Hospitalfor their assistance in retrieving the medical records ofpatients. Also the Plastics Department who is involvedin the treatment of all multi-facial trauma, David Leesof The University of Tasmania for his kind assistanceand Mr David Wiesenfeld of The University ofMelbourne for his kind advice.

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Australian Dental Journal 2002;47:2. 137

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20. Asadi SG, Asadi Z. The aetiology of mandibular fractures at anurban centre. J Roy Soc Health 1997;117:164-167.

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25. Brook IM, Wood N. Aetiology and incidence of facial fracturesin adults. Int J Oral Surg 1983;12:293-298.

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Address for correspondence/reprints:Dr Peter Dongas/Dr Graham M HallOral and Maxillofacial Surgery Unit

Royal Hobart HospitalHobart, Tasmania 7000