Panoramic radiographic survey of hypodontia in Australian Defence Force recruits Anthony Lynham, BDSc*
Key words: Hypodontia prevalence, surveys, third molar agenesis. Abstract Comprehensive dental examinations and panoramic radiographs were used to determine the prevalence of hypodontia in 662 Australian Defence Force recruits. Of the sampled population, 6.3 per cent exhibited some degree of hypodontia (third molar agenesis excluded). Previous studies produced similar results. Third molar agenesis occurred in 22.7 per cent of the sample which again is in agree ment with other studies. There was no statistical difference between the sexes in third molar agenesis; however, there was a significant difference with upper second premolars. Females exhibited an extremely low incidence of absence of maxillary lateral incisors. (Received for publication February 1988. Accepted September 1988.)
Introduction Hypodontia (oligodontia or partial anodontia) ranges from the absence of a single tooth to that of many teeth. Hypodontia involving a single tooth or a few teeth is a common condition. In its severe form it is usually concurrent with a generalized congenital condition such as hereditary ectodermal dysplasia where the few teeth that are present may be deformed or misshapen. Hypodontia is an important condition in that both aesthetics and function can be detrimentally affected. Children with advanced hypodontia, that is, four or more congenitally absent permanent teeth excluding the third molar, tend to have delayed tooth development. reduced mesio-distal crown diameter and abnormal morphology and positions of the teeth.' Australian Dental Journal 1989;35(1):19-22.
Many previous studies of hypodontia have not focused upon third When included, the surveys did not have the benefit of routine panoramic radiograph^.'-^ There is a requirement to examine and document clinical findings of all recruits to the Australian Defence Force. It was the aim of this study to report on the prevalence of hypodontia, with particular emphasis on third molar agenesis, in Australian Defence Force recruits.
Materials and methods The number of individuals examined was 678. The examination included: (a) Medical and dental history questionnaire. (b) Extra- and intra-oral examination including comprehensive charting. (c) Bitewing radiographs (d) Panoramic radiograph. For the purpose of this survey, questions were also asked on whether permanent teeth had been extracted, with particular emphasis on: (a) History of third molar extraction. (b) History of orthodontic treatment which could correlate with the absence of first premolars. This, in addition to any other relevant history of extracted teeth was noted. The individuals each received a panoramic radiograph? which was developed with an automatic processor.$ The film cassettes4 were exposed with 60-65 kVp at 10 mA. *35 Field Dental Unit, Holsworthy, NSW.
tRotograph 230 dental tornograph. HAD S.r.l., Tr-o, Italy. $Durn Automat. Diirr GmbH & Co. KG, BietigheimBissingen, West Germany. g3M type 16 cassette. 3M Health Care, St. Paul, USA. gKonica X-ray film M.G. Konica Corporation, Tokyo, Japan. 19
Table 1. The distribution of hypodontia by sex*
Males Females Total
No. subjects
Mean age? (year)
No. with hypdontia
No. teeth missing
535 127 662
18.6 18.5 18.6
15q28.0) 33(26.0) 183(27.6)
313(77. I ) 93(22.9) 406(100)
*Percentage value in parenthesis. tAge range 16-26 years.
Those subjects with teeth missing and expressing uncertain histories of tooth extraction were excluded from the survey. Six hundred and sixtytwo subjects were suitable for inclusion. These consisted of 535 males (80.7 per cent) and 127 females (19.2 per cent). Their ages ranged from 16-26 years with the mean age for males of 18.6 years and for females 18.5 years. The panoramic films were inspected using an illuminated viewer with the corresponding patient dental record cross-checked to ascertain whether a tooth had been previously extracted. A tooth was noted as being congenitally absent when it could not be found on the film and there was no history of extraction.
Results There were 183 (27.6 per cent) of individuals with varying degrees of hypodontia. There was no significant difference between males and females with 150 of 535 males (28.0 per cent) and 33 of 127 females (26.0 per cent) (Table 1). Sixty-nine individuals had one absent tooth: 59 males (1 1.O per cent) and 10 females (7.9 per cent).
Table 2. Congenitally absent teeth (male and female) expressed as a percentage of total number of suppressed teeth. Maxillary
Mandibular
Tooth
Number
Per cent
Tooth
Number
Per cent
18
75 2 I 12 1 0 5 0 0 10 2 1
18.5 0.49 0.25 2.96 0.25 0 1.23 0 0 2.46 0.49 0.25 2.71 0.25 0.49 17.2
48 47 46 45 44 43 42 41 31 32 33 34 35 36 37 38
86 3 I 14
21.2 0.74 0.25 3.4
17 16 15 14 13 12 11 21 22 23 24 25 26 27 28
20
I1 1 2 70
0 1
2 2 1 1
0 0 15 2 2 38
0
0.25 0.49 0.25 0.25 0.25 0
0 3.69 0.49 0.49 20.7
There were 114 individuals with more than one tooth absent: 91 males (17.0 per cent) and 23 females (18.1 per cent): a total of 17.2 per cent of total surveyed. If third molars are not included, a total of 42 individuals (6.3 per cent) had hypodontia: 31 males (5.7 per cent) and 11 females (8.6 per cent). If third molars are considered alone, 150 individuals (22.7 per cent) had one or more absent, 125 males (23.4 per cent) and 25 females (19.6 per cent). The teeth most commonly missing were the third molars with 315 missing: 77.6 per cent of the total number of missing teeth. The lower third molars were the most commonly congenitally absent teeth: 41.9 per cent of the total number of missing teeth (Table 2). Table 2 shows the bilateral symmetry associated with hypodontia. A total of 59 subjects (8.9 per cent) had bilateral loss that was not associated with further missing teeth. T h e most striking finding of this study is the general agreement with previous studies'-'' with regard to: (a) Prevalence of hypodontia. (b) Prevalence of agenesis of third molars. (c) Order of tooth suppression. T h e three studies concerned with hypodontia using panoramic radiographs utilized Nordic schoolchildren. Bergstram' and Locht4 did not focus on third molar agenesis because of the young age group sampled. Haavikko'O included third molars; however, his sample size of 298 children was small. 1. Prevalence of hypodontia
When third molars are not included, these Nordic studies show 7.4-8.0 per cent of children with hypodontia. T h e present investigation revealed only 6.3 per cent with hypodontia. This lesser figure, however, equates quite well with findings by Castaldi et al.3 who reported 4.1 per cent frequency of hypodontia; McKibben and Brearley,' 5.47 per cent; Ruprecht et a1.,6 5.0 per cent; Grahnen,' in an extensive genetic and clinical study, reported a prevalence of 6.1 per cent. 2. Order of suppressed teeth T h e present results agree with the results of Bergstram.* If third molars are excluded, mandibular second premolars are the most often suppressed followed by maxillary lateral incisors and maxillary second premolars. What is unusual Australian Dental Journal 1990;35:1,
Table 3. Male/female distribution of absent teeth in decreasing order of absence Male Teeth 38 18 35 12 15 36 32 31 16 17
48 28 45 22 25 46 42 41 26 27 23 43 47
Female
Number
Per cent
Teeth
Number
Per cent
135 115 22 14 13 3 2 2 2 2
43.1 36.7 7.0 4.5 4.2 0.96 0.64 0.64 0.64 0.64 0.32 0.32 0.32
38 48 18 28 15 25 35 45 37 47 14 24 17 27 22 42 42
35 30
37.6 32.3 10.6 7.5 4.3 2.2 2.2
1 1 1
10 7 4 2 2 1
1.1
1
1.1
1
1.1
in this study is the low incidence of females showing suppressed lateral incisors (Table 3). The reported difference in maxillary second premolars between the sexes is in agreement with Bergstr0m.l There is no significant sex difference with hypodontia when third molars are included or excluded from the total sample. Bergstrornl also reported in his study of 2589 schoolchildren an absence of 30 first and second molars. The present study reports 13 absent. This is probably due to two cases with multiple suppressed teeth in which the mandibular second molars were missing. These individuals were female. 3. Third molar agenesis
Only one other studylo has used rotational panoramic films to assess the agenesis of third molars. It sampled 298 children aged between 14 and 18 years. This result of 20.8 per cent of individuals compared favourably with the results of the present study of 22.7 per cent (Table 4). Other researchers, not having the benefit of rotational panoramic films, reported similar findings. Gravely8 and Grahnen' found 25 per cent of individuals with missing third molars. Goblirsch" and Nanda9 found a low 9 per cent prevalence of agenesis of third molars.
Table 4. Comparison of frequency of third molar agenesis ~
Males Females
~
Haavikko (per cent)
Present study (per cent)
21.2 20.1
23.4 19.5
Australian Dental Journal 1990;35:1
The present study found no significant difference by sex in third molar agenesis. This agrees with the results of Haavikko."
Discussion This study reports on the prevalence of hypodontia in a group of Australian Defence Force recruits, focusing on the absence of third molars. Due to the age group involved (16-26 years), it was sometimes difficult to ascertain whether teeth had been extracted previously. This may be a factor involved in the number of first and second molars found missing in the survey. The prevalence of third molar agenesis did not suffer from this problem as extraction of these teeth would have been a recent event remembered for some time. The prevalence of hypodontia for recruits to the Australian Defence Force is similar to other sampled populations. The frequency of third molar suppression is in agreement with other studies reviewed with no significant difference between the sexes. Conclusions This study showed that: 1. 22.7 per cent of the sampled population had third molar agenesis; and 2. 6.3 per cent of the sampled population had hypodontia when third molars were excluded. These results agree with reviewed studies utilizing panoramic radiographs as their method of survey. Acknowledgements The assistance of the following people is greatly appreciated in the preparation of this article: 1. Miss P. Burke and staff, Bridges Memorial Library, Royal Military College, Duntroon. 2. Major M. K. Thomas and staff, 21 Dental Unit, Duntroon. 3. Major M. Coombs and staff, 12 Dental Unit, Kapooka. References 1. Rune B, Sarnas KV. Tooth size and tooth formation in chil-
dren with advanced hypodontia. Angle Orthod 1974;44:312-6. 2. Bergstrom K. An orthopantomographic study of hypodontia,
supernumeraries and other anomalies in schoolchildren between the age of 8-9 years. Swed Dent J 1977;1:145-57. 3. Castaldi CR, Badnarchuk A, Macrae PD, Zachert WA. Incidence of congenital anomalies in permanent teeth in a group of Canadian children aged 6-9. J Can Dent As= 1966;32:154-9. 21
4. Locht S.Panoramic radiographic examination of 704 Danish children aged 9-10 years. Community Dent Oral Epidemiol 1980;8:375-80. 5. McKibben DR, Brearley LJ. Radiographic determination of the prevalence of selected dental anomalies in children. J Dent Child 1971;28:390-8. 6. Ruprecht A, Batniji S, El-Neweihi E. Incidence of oligodontia (hypodontia). J Oral Med 1986;41:43-6. 7. Grahnen H.Hypodontia in the permanent dentition. A clinical and genetical investigation. Odont Revy 1956;7:Suppl3. 8. Gravely JF. A radiographic survey of third molar development. Br Dent J 1965;119:397-401.
22
9. Nanda RS. Agenesis ofthe third molar in man. Am J Onhod 1954;40:698-706. 10. Haavikko K. Hypodontia of permanent teeth. Proc Finn Dent SOC1971;67:1849-54.
Address for correspondenceheprints: Major A. J. Lynham, Officer Commanding, 35 Field Dental Unit, Johore Road, Military Post Office, Holsworthy New South Wales, 2173.
Australian Dental Journal 1990;35:1,
Key words: Hypodontia prevalence, surveys, third molar agenesis. Abstract Comprehensive dental examinations and panoramic radiographs were used to determine the prevalence of hypodontia in 662 Australian Defence Force recruits. Of the sampled population, 6.3 per cent exhibited some degree of hypodontia (third molar agenesis excluded). Previous studies produced similar results. Third molar agenesis occurred in 22.7 per cent of the sample which again is in agree ment with other studies. There was no statistical difference between the sexes in third molar agenesis; however, there was a significant difference with upper second premolars. Females exhibited an extremely low incidence of absence of maxillary lateral incisors. (Received for publication February 1988. Accepted September 1988.)
Introduction Hypodontia (oligodontia or partial anodontia) ranges from the absence of a single tooth to that of many teeth. Hypodontia involving a single tooth or a few teeth is a common condition. In its severe form it is usually concurrent with a generalized congenital condition such as hereditary ectodermal dysplasia where the few teeth that are present may be deformed or misshapen. Hypodontia is an important condition in that both aesthetics and function can be detrimentally affected. Children with advanced hypodontia, that is, four or more congenitally absent permanent teeth excluding the third molar, tend to have delayed tooth development. reduced mesio-distal crown diameter and abnormal morphology and positions of the teeth.' Australian Dental Journal 1989;35(1):19-22.
Many previous studies of hypodontia have not focused upon third When included, the surveys did not have the benefit of routine panoramic radiograph^.'-^ There is a requirement to examine and document clinical findings of all recruits to the Australian Defence Force. It was the aim of this study to report on the prevalence of hypodontia, with particular emphasis on third molar agenesis, in Australian Defence Force recruits.
Materials and methods The number of individuals examined was 678. The examination included: (a) Medical and dental history questionnaire. (b) Extra- and intra-oral examination including comprehensive charting. (c) Bitewing radiographs (d) Panoramic radiograph. For the purpose of this survey, questions were also asked on whether permanent teeth had been extracted, with particular emphasis on: (a) History of third molar extraction. (b) History of orthodontic treatment which could correlate with the absence of first premolars. This, in addition to any other relevant history of extracted teeth was noted. The individuals each received a panoramic radiograph? which was developed with an automatic processor.$ The film cassettes4 were exposed with 60-65 kVp at 10 mA. *35 Field Dental Unit, Holsworthy, NSW.
tRotograph 230 dental tornograph. HAD S.r.l., Tr-o, Italy. $Durn Automat. Diirr GmbH & Co. KG, BietigheimBissingen, West Germany. g3M type 16 cassette. 3M Health Care, St. Paul, USA. gKonica X-ray film M.G. Konica Corporation, Tokyo, Japan. 19
Table 1. The distribution of hypodontia by sex*
Males Females Total
No. subjects
Mean age? (year)
No. with hypdontia
No. teeth missing
535 127 662
18.6 18.5 18.6
15q28.0) 33(26.0) 183(27.6)
313(77. I ) 93(22.9) 406(100)
*Percentage value in parenthesis. tAge range 16-26 years.
Those subjects with teeth missing and expressing uncertain histories of tooth extraction were excluded from the survey. Six hundred and sixtytwo subjects were suitable for inclusion. These consisted of 535 males (80.7 per cent) and 127 females (19.2 per cent). Their ages ranged from 16-26 years with the mean age for males of 18.6 years and for females 18.5 years. The panoramic films were inspected using an illuminated viewer with the corresponding patient dental record cross-checked to ascertain whether a tooth had been previously extracted. A tooth was noted as being congenitally absent when it could not be found on the film and there was no history of extraction.
Results There were 183 (27.6 per cent) of individuals with varying degrees of hypodontia. There was no significant difference between males and females with 150 of 535 males (28.0 per cent) and 33 of 127 females (26.0 per cent) (Table 1). Sixty-nine individuals had one absent tooth: 59 males (1 1.O per cent) and 10 females (7.9 per cent).
Table 2. Congenitally absent teeth (male and female) expressed as a percentage of total number of suppressed teeth. Maxillary
Mandibular
Tooth
Number
Per cent
Tooth
Number
Per cent
18
75 2 I 12 1 0 5 0 0 10 2 1
18.5 0.49 0.25 2.96 0.25 0 1.23 0 0 2.46 0.49 0.25 2.71 0.25 0.49 17.2
48 47 46 45 44 43 42 41 31 32 33 34 35 36 37 38
86 3 I 14
21.2 0.74 0.25 3.4
17 16 15 14 13 12 11 21 22 23 24 25 26 27 28
20
I1 1 2 70
0 1
2 2 1 1
0 0 15 2 2 38
0
0.25 0.49 0.25 0.25 0.25 0
0 3.69 0.49 0.49 20.7
There were 114 individuals with more than one tooth absent: 91 males (17.0 per cent) and 23 females (18.1 per cent): a total of 17.2 per cent of total surveyed. If third molars are not included, a total of 42 individuals (6.3 per cent) had hypodontia: 31 males (5.7 per cent) and 11 females (8.6 per cent). If third molars are considered alone, 150 individuals (22.7 per cent) had one or more absent, 125 males (23.4 per cent) and 25 females (19.6 per cent). The teeth most commonly missing were the third molars with 315 missing: 77.6 per cent of the total number of missing teeth. The lower third molars were the most commonly congenitally absent teeth: 41.9 per cent of the total number of missing teeth (Table 2). Table 2 shows the bilateral symmetry associated with hypodontia. A total of 59 subjects (8.9 per cent) had bilateral loss that was not associated with further missing teeth. T h e most striking finding of this study is the general agreement with previous studies'-'' with regard to: (a) Prevalence of hypodontia. (b) Prevalence of agenesis of third molars. (c) Order of tooth suppression. T h e three studies concerned with hypodontia using panoramic radiographs utilized Nordic schoolchildren. Bergstram' and Locht4 did not focus on third molar agenesis because of the young age group sampled. Haavikko'O included third molars; however, his sample size of 298 children was small. 1. Prevalence of hypodontia
When third molars are not included, these Nordic studies show 7.4-8.0 per cent of children with hypodontia. T h e present investigation revealed only 6.3 per cent with hypodontia. This lesser figure, however, equates quite well with findings by Castaldi et al.3 who reported 4.1 per cent frequency of hypodontia; McKibben and Brearley,' 5.47 per cent; Ruprecht et a1.,6 5.0 per cent; Grahnen,' in an extensive genetic and clinical study, reported a prevalence of 6.1 per cent. 2. Order of suppressed teeth T h e present results agree with the results of Bergstram.* If third molars are excluded, mandibular second premolars are the most often suppressed followed by maxillary lateral incisors and maxillary second premolars. What is unusual Australian Dental Journal 1990;35:1,
Table 3. Male/female distribution of absent teeth in decreasing order of absence Male Teeth 38 18 35 12 15 36 32 31 16 17
48 28 45 22 25 46 42 41 26 27 23 43 47
Female
Number
Per cent
Teeth
Number
Per cent
135 115 22 14 13 3 2 2 2 2
43.1 36.7 7.0 4.5 4.2 0.96 0.64 0.64 0.64 0.64 0.32 0.32 0.32
38 48 18 28 15 25 35 45 37 47 14 24 17 27 22 42 42
35 30
37.6 32.3 10.6 7.5 4.3 2.2 2.2
1 1 1
10 7 4 2 2 1
1.1
1
1.1
1
1.1
in this study is the low incidence of females showing suppressed lateral incisors (Table 3). The reported difference in maxillary second premolars between the sexes is in agreement with Bergstr0m.l There is no significant sex difference with hypodontia when third molars are included or excluded from the total sample. Bergstrornl also reported in his study of 2589 schoolchildren an absence of 30 first and second molars. The present study reports 13 absent. This is probably due to two cases with multiple suppressed teeth in which the mandibular second molars were missing. These individuals were female. 3. Third molar agenesis
Only one other studylo has used rotational panoramic films to assess the agenesis of third molars. It sampled 298 children aged between 14 and 18 years. This result of 20.8 per cent of individuals compared favourably with the results of the present study of 22.7 per cent (Table 4). Other researchers, not having the benefit of rotational panoramic films, reported similar findings. Gravely8 and Grahnen' found 25 per cent of individuals with missing third molars. Goblirsch" and Nanda9 found a low 9 per cent prevalence of agenesis of third molars.
Table 4. Comparison of frequency of third molar agenesis ~
Males Females
~
Haavikko (per cent)
Present study (per cent)
21.2 20.1
23.4 19.5
Australian Dental Journal 1990;35:1
The present study found no significant difference by sex in third molar agenesis. This agrees with the results of Haavikko."
Discussion This study reports on the prevalence of hypodontia in a group of Australian Defence Force recruits, focusing on the absence of third molars. Due to the age group involved (16-26 years), it was sometimes difficult to ascertain whether teeth had been extracted previously. This may be a factor involved in the number of first and second molars found missing in the survey. The prevalence of third molar agenesis did not suffer from this problem as extraction of these teeth would have been a recent event remembered for some time. The prevalence of hypodontia for recruits to the Australian Defence Force is similar to other sampled populations. The frequency of third molar suppression is in agreement with other studies reviewed with no significant difference between the sexes. Conclusions This study showed that: 1. 22.7 per cent of the sampled population had third molar agenesis; and 2. 6.3 per cent of the sampled population had hypodontia when third molars were excluded. These results agree with reviewed studies utilizing panoramic radiographs as their method of survey. Acknowledgements The assistance of the following people is greatly appreciated in the preparation of this article: 1. Miss P. Burke and staff, Bridges Memorial Library, Royal Military College, Duntroon. 2. Major M. K. Thomas and staff, 21 Dental Unit, Duntroon. 3. Major M. Coombs and staff, 12 Dental Unit, Kapooka. References 1. Rune B, Sarnas KV. Tooth size and tooth formation in chil-
dren with advanced hypodontia. Angle Orthod 1974;44:312-6. 2. Bergstrom K. An orthopantomographic study of hypodontia,
supernumeraries and other anomalies in schoolchildren between the age of 8-9 years. Swed Dent J 1977;1:145-57. 3. Castaldi CR, Badnarchuk A, Macrae PD, Zachert WA. Incidence of congenital anomalies in permanent teeth in a group of Canadian children aged 6-9. J Can Dent As= 1966;32:154-9. 21
4. Locht S.Panoramic radiographic examination of 704 Danish children aged 9-10 years. Community Dent Oral Epidemiol 1980;8:375-80. 5. McKibben DR, Brearley LJ. Radiographic determination of the prevalence of selected dental anomalies in children. J Dent Child 1971;28:390-8. 6. Ruprecht A, Batniji S, El-Neweihi E. Incidence of oligodontia (hypodontia). J Oral Med 1986;41:43-6. 7. Grahnen H.Hypodontia in the permanent dentition. A clinical and genetical investigation. Odont Revy 1956;7:Suppl3. 8. Gravely JF. A radiographic survey of third molar development. Br Dent J 1965;119:397-401.
22
9. Nanda RS. Agenesis ofthe third molar in man. Am J Onhod 1954;40:698-706. 10. Haavikko K. Hypodontia of permanent teeth. Proc Finn Dent SOC1971;67:1849-54.
Address for correspondenceheprints: Major A. J. Lynham, Officer Commanding, 35 Field Dental Unit, Johore Road, Military Post Office, Holsworthy New South Wales, 2173.
Australian Dental Journal 1990;35:1,
