Abstract
Objective
The aim of this study was to assess the prevalence and pattern of congenital missing teeth in the permanent dentition (excluding wisdom teeth), among Turkish children in a 4-year period (2009-2012).
Methods
The study group comprised 1658 children (873 girls, 785 boys). The children were examined in Department of Pediatric Dentistry, Dental School of Marmara University. A chi square test was used to determine the difference in the prevalence of hypodontia between genders.
Results
The prevalence of hypodontia was 6.2% (6.3% girls, 6% boys) with no statistically significant difference between the genders (P=0.601). The most frequently missing tooth were the mandibular left second premolars, 63 (20.7%), followed by the mandibular right second premolars, 61(20.1%), maxillary left premolars, 31 (10.2%). There were 89 anterior and 214 posterior missing teeth. Bilateral hypodontia was observed in 70 (39 girls, 31 boys) patients (67.9%). The most common bilateral missing teeth were the mandibular second premolar (22 girls, 21 boys) (42.1%) and the maxillary second premolar (6 girls, 15 boys) (20.5%). The mandibular left second premolar (9 boys, 8 girls) was the most frequent unilaterally missing tooth (5.6%) followed by the mandibular right second premolar (10 girls, 6 boys) (5.28%).
Conclusion
The obtained results point to the importance of detailed clinical and radiographic examination. These help with long-term treatment planning according to a child’s individual requirements.
Key words: Anodontia, Hypodontia, Child, Turkey
INTRODUCTION:
Hypodontia is often used as a collective term for congenital absence of primary or secondary teeth, although specifically it describes the absence of one to six teeth excluding third molars. Oligodontia refers to the absence of more than six teeth, excluding third molars. Dental agenesis affects more frequently the permanent dentition rather than the primary dentition (1-4). Hypodontia may detrimentally affect the aesthetics and function (4-7). Developmentally missing teeth may be the result of numerous etiologic factors such as changes of the dental lamina formation, failure of tooth germ to develop at the optimal time, space limitation, systemic condition and genetic factors (8, 9). Apart from the third molars, the most commonly affected teeth by hypodontia are second premolars and lateral incisors (8, 10). Investigating the prevalence of hypodontia is of significant clinical value, in terms of early diagnosis and effective treatment planning (5).
The prevalence of hypodontia in the permanent dentition has been reported to be 0.3% to 10.1%, depending on the population studied (11). In approximately 80% of reported cases of hypodontia, only 1 or 2 teeth are missing; in 10%, 4 or more teeth are missing, while in less than 1%, 6 or more teeth are absent (12).
The literature consists of numerous studies on the prevalence of hypodontia (third molars excluded) in the permanent dentition, among different populations (Table 1).
Table 1. Prevalence of Hypodontia in Different Population.
| Author | Year | Country | Age (year) |
Sample size | Female % | Male % | M/F | Prevalence |
|---|---|---|---|---|---|---|---|---|
| Haaviko et al. | 1971 | Finland | 5-13 | 1041 | 8 | |||
| Backmann et al. | 1974 | Switzerland | 7 | 8694 | 7.7 | |||
| Rolling et al. | 1980 | Denmark | 9-10 | 3325 | 7.8 | 7.7 | 0.98 | 7.8 |
| Davis et al. | 1987 | Hong Kong | 12 | 1093 | 0.78 | 6.9 | ||
| Aasheim et al. | 1993 | Norway | 7-10 | 1953 | 7.2 | 0.8 | 0.806 | 6.5 |
| Meza et al. | 2003 | Mexico | 9-20 | 668 | 2.7 | |||
| Fekonja et al. | 2005 | Slovenia | 12 | 212 | 7.1 | 4.2 | 0.591 | 11.3 |
| Endo et al. | 2006 | Japan | 5-15 | 3358 | 9.3 | 8.5 | 0.914 | 7.5 |
| Altug-Atac et al. | 2007 | Turkey | 8-15 | 3043 | 3.1 | 2.1 | 0.677 | 2.6 |
| Goya et al. | 2008 | Japan | 3-17 | 2072 | 10.8 | 8.7 | 0.806 | 9.4 |
| Gomes et al. | 2010 | Brazil | 10-16 | 1049 | 7.4 | 5.1 | 0.689 | 6.3 |
The differences in frequencies could be explained by the variety in samples with respect to measuring techniques—different methods of radiography and clinical examinations, age, gender, geographic or demographic profiles (2, 4, 13, 14). The pattern and prevalence of hypodontia can vary in different ethnic groups (15).
Evolutionary changes might as well contribute to the differences; some researchers suggested that hypodontia had increased in prevalence through time (2) whereas some studies do not support this statement (14, 15).
Several studies reported a higher presence of cancer in people with hypodontia (16-18). Fekonja et al. (19) stated that the results of their study statistically support a possible association between EOC (epithelial ovarian cancer) and hypodontia. Because of that reason, hypodontia can be recognized early in life, this finding could possibly help in an earlier detection of EOC, resulting in better prognosis and treatment in earlier stages of the disease. Earlier EOC diagnosis and treatment could save many lives.
Despite numerous studies, there are a limited number of comprehensive studies regarding hypodontia among Turkish children in the literature. Therefore, the aim of this study was to assess the prevalence and pattern of congenital missing in the permanent dentition (excluding third molars), among a group of Turkish children, during 2009-2012.
MATERIALS AND METHODS:
In this descriptive cross-sectional study, we reviewed the records of Turkish children treated between 01/01-2009 and 31/12-2012. All children visited the Department of Pediatric Dentistry, Dental School of Marmara University, Istanbul, Turkey. A total of 1658 children (785 boys, 873 girls) were included in this study. Diagnosis of hypodontia was based on pretreatment panoramic radiographs. Third molars were not evaluated in this study. The exclusion criteria comprised the presence of anodontia, developmental anomalies (ectodermal dysplasia, cleft lip and palate and syndromes), any history of systemic diseases, tooth extractions, trauma, and history of orthodontic treatment, poor image quality, or incomplete dental records. Panoramic views were used to confirm the diagnosis of hypodontia. A tooth was diagnosed as congenitally missing when there was no mineralization of its crown on panoramic images and no evidence of its extraction. Aasheim and Ogaard (20) reported that no tooth, excluding third molars was found to mineralize in patients after age 12 years. The visibility of tooth germs on radiographs depends on their mineralization stage, and there are major differences in mineralization stage and dental age in individuals of the same chronological age. The overall prevalence of hypodontia in the permanent dentition (excluding missing third molars), as well as its pattern of occurrence regarding the involved sides (left vs. right / anterior vs. posterior), tooth types, and gender were investigated by a pediatric dentist.
Statistical analysis
Data were collected and entered into the SPSS 20.00 program for statistical analysis (IBM SPSS package). The Chi square test was used to analyze differences in the distribution of hypodontia by gender, jaw and side. Bar charts were used to show the distribution of missing teeth according to age and gender.
RESULTS:
Apart from the third molars, congenitally missing teeth were observed in the permanent dentition of 102 (6.2%) children, including 55 girls (6.3%) and 47 boys (6%). There was no significant difference between the prevalence of hypodontia in boys and girls (P = 0.601).
A total of 303 teeth (excluding third molars) were missing (158 in girls and 145 in boys). Therefore, an average number of 2.81±1.94 missing teeth per children was calculated (average of 2.72±1.95 missing teeth for each girl, and 2.91±1.95 missing teeth for each boy). The first attendance at the clinic (Figure 1) was mostly between 10 and 12 years of age.
Figure 1.
_58-64-f1.jpg)
Age and gender distribution of hypodontia patients
Among the individuals with hypodontia, 61 (59.8%) had one or two teeth missing congenitally. There was no significant difference between the number of missing teeth in boys 26 (42.62%) and girls 35 (57.38%), (P=0.257), (Table 2).
Table 2. Distribution of the number of missing teeth.
| Number of missing teeth | Girls (n=55) Number(%) |
Boys (n=47) Number(%) |
Total (n=102) Number(%) |
|---|---|---|---|
| 1 | 14(26) | 15(32) | 28(27) |
| 2 | 21(38) | 11(23) | 32(31) |
| 3 | 6(11) | 4(9) | 10(10) |
| 4 | 6(11) | 8(17) | 14(14) |
| 5 | 2(4) | 2(4) | 4(4) |
| 6 | 3(5) | 2(4) | 6(6) |
| 6+ | 3(5) | 5(11) | 8(8) |
The most common tooth types were the mandibular second left premolar 63 (20.7%), the mandibular second right premolar 61 (20.1%), and maxillary left premolar 31 (10.2%). On the other hand, the maxillary central incisors, mandibular canines, maxillary first and second molars, mandibular first molars in both arches showed no congenital absence in the sample of Turkish girls. The tooth types without congenital absence in Turkish boys are fewer, just mandibular canines, maxillary and mandibular second molars.
A total of 303 teeth (excluding third molars) were missing (158 in girls and 145 in boys).
The prevalence rates for missing teeth in the maxilla and mandible were 46.2% and 53.8% (n = 140 maxilla + 163 mandible) (Figure 2), respectively. The difference between maxillary and mandibular missing teeth in boys and girls was not statistically significant (P=0.282), Also, no significant differences were seen between the right and left sides of males and females (P=0.427), and in the right and left sides of the overall population (P=0.427). Hypodontia prevalence in the right and left quadrants (n=149 right + 154 left quadrants) was 49.2% and 50.8%, respectively (Table 3).
Figure 2.
_58-64-f2.jpg)
Frequency distribution (%) of the missing teeth. Max. = Maxilla (n:140) ; Mand. = Mandible (n = 163).; G= Girl; B = Boy
Table 3. The number of missing teeth with respect to the affected jaws and sides.
| Number of missing teeth | Girls (n=158) Number(%) |
Boys (n=145) Number(%) |
Total (n=303) Number(%) |
|---|---|---|---|
| Maxilla | 70- (44%) | 70- (48%) | 140- (46%) |
| Mandible | 88- (56%) | 75- (52%) | 163- (54%) |
| Right | 79- (50%) | 70- (48%) | 149- (49%) |
| Left | 79- (50%) | 75- (52%) | 154- (51%) |
There were 89 anterior and 214 posterior missing teeth. Bilateral hypodontia was observed in 70 (39 girls, 31 boys) patients (67.9%). The most common bilaterally missing teeth were the mandibular second premolar (22 girls, 21 boys) (42.1%) and the maxillary second premolar (6 girls, 15 boys) (20.5%). Of the teeth missing bilaterally, 92 pairs were missing simultaneously in the maxilla and mandible, among which, the mandibular second left premolar was the most frequently missing tooth (20.7%). The mandibular left second premolar (9 boys, 8 girls) was the most frequent unilaterally missing tooth (5.6%) followed by the mandibular right second premolar (10 girls, 6 boys) (5.28%).
In this study, there were no syndromes and systemic diseases in all patients and only 7 patients (6.8%) reported familial history about missing teeth.
DISCUSSION:
The prevalence of congenitally missing teeth was observed in the permanent dentition of 6.2% subjects in this study. Sisman (21) showed that the prevalence of hypodontia was 7.54% for Turkish orthodontic patient population. These results confirm that hypodontia is not common in Turkish children. On the other hand, Nik-Hussein (7) found that the prevalence was 2.8; Meza (10) found that the prevalence was 2.7. In contrast, Fekonja (32) and Goya (4) found that the prevalence of hypodontia was 11.3 and 9.4. There is a great variation in the prevalence of hypodontia in different societies.
In this study there was no significant difference between the prevalence of hypodontia in boys and girls. Females presented a higher prevalence of hypodontia, however no statistically significant difference was observed, which is in accordance with the majority of reports by Grahnén (22), Haavikko (23), Seow (24), Fekonja (32), Endo (25) and Meza (10). But Larmour (12) found that hypodontia in the primary dentition has no significant gender distribution, on the other hand, in the permanent dentition females are affected more frequently than males by a ratio of 3:2.
The average number of missing teeth per child was 2.81 in this study. Tunc et al. (11) observed an average number of 1.99 teeth per child and Kirzioglu (26) found that an average number of 2.6 teeth per child. Aashaim and Ogaard (20) and Rolling (27) observed an average number of 1.71 and 1.77 teeth per child. Besides, Goya (4) and Endo (25) found that the numbers of missing teeth per affected child were 2.84 and 2.4.
The first attendance at the clinic occurred mostly between the ages of 10 and 12 years. Detecting a younger patient with hypodontia results either from chance observation or family history, it might be expected that the majority of cases would be identified in the mixed dentition phase. For these cases, it is likely that there are difficulties in locating an appropriate clinic to which a referral for advice or treatment would be made (28). In general, diagnosis of tooth agenesis in the permanent dentition should be made after the age of 6 because the mineralization of the permanent dentition can reliably be expected to have commenced (29, 30). That is why the age range of this study was limited between 7 and 13.
In the present study, of the individuals identified with hypodontia, 61% had one or two missing teeth. Peker (29) obtained similar results of one or two missing teeth. Other studies (Haavikko (23), Rřlling (27), Davis (31), Fekonja (32), Gomes (33) and Goya (4)) reported a higher frequency of one or two missing teeth. Most cases involved agenesis of just one or two teeth, and therefore most of the affected individuals suffer only a mild form of hypodontia.
The most common congenital missing tooth types were the mandibular second left premolar, the mandibular second right premolar and maxillary left premolar in this study respectively. There is some variation in the literature concerning the description of the most frequently missing tooth, excluding third molars. The mandibular second premolar is normally the most frequently missing tooth reported by Rřlling (27), Bäckman (34), Polder (14), Mattheeuws (35), Endo (25), Tunc (11), Goya (4) and Kirzioglu (26). However, other studies have also shown the permanent maxillary lateral incisor to be the most affected tooth (Meza (10), Fekonja (32), Gomes (33), Altug-Atac (1)).
We found more missing teeth in the mandible than in the maxilla and the difference was not significant. This result was in agreement with Kirzioglu’s study (26). However, Peker (29) found more missing teeth in the maxilla than in the mandible. Fekonja (32) and Wong (36) found missing teeth considerably more frequently in the maxilla than in the mandible in orthodontic patients. Gomes (33) found maxillary hypodontia in 59.2% of patients and in the mandible amounting to 40.8% with an overall ratio of 1.45: 1 in orthodontic patients.
Bilateral hypodontia was observed in 67.9% patients. The most common bilaterally missing teeth were the mandibular second premolar and the maxillary second premolar. Goya et al. (4) found that symmetry of congenitally missing teeth was predominant (74.6%) and Kirzioglu et al. (26) observed that bilaterally missing teeth was 73.2%. Moreover, symmetrical hypodontia was predominant, being found in both the contralateral and antagonistic quadrant, possibly suggesting a strong genetic pattern.
Although hypodontia can occur in over 60 different syndromes, these anomalies can occur without any syndrome or systemic disease. However, hypodontia is seen more commonly in non-syndromic or familial form than syndromic form (13, 37). In this study, there were no syndromes and systemic diseases in all patients and only 7 patients (6.8%) reported familial history about missing teeth.
CONCLUSION
Epidemiological studies can be used for the raising of public health awareness by sufficiently informing on the specificities of every population. The results of this study can be considered representative of Turkish children. The prevalence, location and distribution of hypodontia could provide useful data for future studies.
Our data point to the importance of a detailed and careful radiographic examination. This could help in a long-term and effective treatment planning according to a child’s individual requirements.
Footnotes
None declared
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