A statistical study of the association of seven dental anomalies in the Brazilian population/Estudio estadistico de la asociacion de siete anomalias dentales en la poblacion Brasilena.
There are more than 500 anomalies caused by simple genetic factors and perhaps an equal number of others derived from multifactorial causes or chromosome aberrations where there are orofacial alterations. The frequency of symptom-less carriers of heredity anomalies that affect the teeth can be calculated from genetic data that is often essential to advise on the probability of affected offspring (Salzano, 1982). The specter of a possible association among dental anomalies was reported by Hoffmeister between 1975 and 1985 (Hoffmeister, 1975; 1977; 1985). The following manifestations were found in three consecutive generations of one family: multiple tooth loss, upper side incisive agenesis, ectopic eruption of the permanent maxillar first molar and intra-bone displacement of the upper canines. The objective of the present investigation was to prove the existence of significant association among seven different types of anomalies: second pre-molar agenesis, upper side incisive reduced in size, lower first molar infra-ochlesis, enamel hypoplasia, first pre-molar ectopic eruption, supra numerous teeth and upper canine ectopic eruption in a sample of the Brazilian population without dental treatment consisting of individuals aged 7 to 14 years to identify the etiological and clinical relevance of these associations.
MATERIAL AND METHOD
The sample was obtained from a total of 172 patients aged 7 to 14 who were attended at the Clinica Infantil da Fundacao Educacional de Barretos. Radiographic material was obtained from eleven patients who presented one of the anomalies on first diagnosis. Individuals were excluded from this sample who had craniofacial malformation, cleft palate and/or lips, after effects of traumatic accidents to the teeth or multiple and/or advanced cavities. Other individuals were excluded due to incomplete or inadequate registration, ethnic diversity (only Caucasian individuals were included in the study) or family correlation (twins or siblings were excluded from the study).
The frequency of each of the seven anomalies studied was estimated from the samples of 172 individuals and analyzed. To ascertain whether the occurrence of a determined anomaly was independent from the occurrence of another, or whether there was association among them, the Fisher exact test was applied to the sample that is indicated mainly for situations where the expected total in at least one of the categories is less than five. For this, 2 x 2 contingency tables were constructed, stating the presence or absence of the 'A' anomaly with the presence or absence of anomaly 'B', always fixing the general total at 172.
This study was approved by the Research Ethics Committee of the Fundacao Educacional de Barretos (nr. 02/2001).
RESULTS AND DISCUSSION
Table I shows the occurrence frequency of each one of the seven anomalies. A total of eleven individuals (6.4%) presented at least one of the anomalies investigated. Of these, only three (27.3%) presented two or more of these anomalies simultaneously. The most frequent anomaly was enamel hypoplasia, which was detected in 3.5% of the individuals. The least frequent was the palate displacement of the maxillar canine, that was not observed at all.
There are few studies that report the frequency of such anomalies so that comparison with other populations is difficult. Among these, the frequency of supra numerous teeth was the most explored.
A study analyzed a population in the United States consisting of 1.100 patients of whom seven presented supra numerous teeth with a frequency of 0.64% (Baccetti, 1993). In a study that analyzed 2.264 black American children, the rate of supra numerous teeth was 1.49% (Kotsomitis & Freer, 1997), much higher than the frequency detected in a Nigerian population (0.098%) consisting of 13 patients (Baccetti, 1998a).
The frequency of supra numerous teeth detected in our study (2.3%) was higher than that reported in the literature that differentiates the Brazilian population and therefore further studies are needed to refine these comparisons.
A single study that analyzed a second anomaly (reduced size of the lateral maxillar incisive) presented a 29.4% frequency in a Nigerian population (Baccetti, 1998b), much higher than that detected in our study (1.2%).
Eighty individuals in a study carried out on a family analyzing three generations presented several anomalies associated with infra-ochlesis of the first molar. More recently, taurodontism of the first lower molar was detected in 24.8% of patients with congenital tooth loss, and first molar infraochlesis was detected in 65.7% of the same samples (Rubenstein et al., 1991; Bruce et al., 1994). The association among four anomalies (first molar ectopic eruption, lower first molar infra-ochlesis, upper canine ectopic eruption and premolar agenesis) was investigated by Bjerklin et al. in 1992 (Umweni & Osunbor, 2002). The findings indicated the presence of a reciprocal association among pre-molar agenesis and infra ochlesis of the lower first molar. This association was also confirmed by a subsequent study using a large sample (Umweni & Ojo, 1997). Upper canine ectopic eruption increased significantly when any one of the other three conditions mentioned above was detected, while lower first molar ectopic eruption increased the prevalence of first molar infra-ochlesis. These results were interpreted to sustain the hypothesis of a common, presumably hereditary, etiology for the study of dental disturbance and it is known that each disturbance has incomplete penetration. Finally, a high prevalence of associated dental anomalies (76.02%) was calculated from a sample of 169 inherited syndromes with dental disturbances, strongly suggesting the possibility of genetic correlation among tooth number, size, form and structural characteristics (Lai & Seow, 1989). Concrete evidence suggests that genes perform a preponderant function in the etiology of dental anomalies. Some type of genetically controlled interrelation may exist for some of these anomalies shown by their association frequencies. It has also been speculated that a "common genetic defect" may lead to different phenotypic manifestations, including tooth loss, malformation, ectopic eruption and bad positioning. Thus dental anomalies may be caused by a disturbance inherited in the tooth structure development. Knowing that these dental anomalies can be inherited, a family history and early clinical diagnosis or radiographic detection can alert parents and clinics to the high probability of detecting others in the same individuals and similar anomalies in other members of the family (Seow & Lai, 1989). In 1998, Baccetti studied association patterns among seven types of dental anomalies (second pre-molar agenesis, reduced size of the upper side incisive, lower first molar infraochlesis, enamel hypoplasia, first molar ectopic eruption, supra numerous teeth and upper canine ectopic eruption) (Bjerklin et al., 1992).
A reciprocal association (p<0.005) was found among five of the anomalies (second pre-molar agenesis, reduced size of the upper side incisive, lower first molar infra-ochlesis, enamel hypoplasia and upper canine ectopic eruption) suggesting a common genetic origin for these conditions. Further in 1998, Baccetti studied the association pattern among five types of dental anomalies (second pre-molar agenesis, reduced size of the upper side incisive, lower first molar infraochlesis, first molar ectopic eruption, upper canine ectopic eruption) (Baccetti & Tollaro, 1995).
Significant reciprocal association (p<0.008) was detected among four types of dental anomalies (second premolar agenesis, reduced size of the upper side incisive, upper first molar infra-ochlesis, upper canine ectopic eruption).
First molar ectopic eruption seems to be a separate pathological entity compared with all the other dental anomalies examined (Baccetti & Tollaro).
Table II shows the probability of independence among the anomalies studied in this study, obtained by the Fisher exact test. Assuming a 5% significance level (a=0,05), there was significant association among six pairs of anomalies. There was anomaly sharing by the patients in only in one case (second pre-molar aplasia and enamel hypoplasia) and there was no probability of significant association among the anomalies (Table 2). These results strongly indicate that the studied anomalies are related but a wider sample is still necessary to obtain stronger conclusion about the association pattern of such anomalies in the Brazilian population.
ACKNOWLEDGEMENTS: We thank the patients and their families for cooperating, Rosangela Goulart for technical assistance and the Faculdades Unificadas da Fundacao Educacional de Barretos for financial support.
Baccetti, T. Analisi della prevalenza di anomalie dentali isolate ed associate nelle sindromi ereditarie: modello per la valutazione del controllo genetico sulle caratteristiche della dentatura. Minerva Stomatol., 42(6):281-94, 1993.
Baccetti, T. A controlled study of associated dental anomalies. Angle Orthod., 68(3):267-74, 1998a. Baccetti, T. A clinical and statistical study of etiologic aspects related to associated tooth anomalies in number, size and position. Minerva Stomatol., 47(12):655-63, 1998b.
Baccetti, T. & Tollaro, I. Infraocclusion of primary molars as a dental anomaly of genetic origin. In: Radlanski, R. J. & Renz, H. Eds. Proceedings of 10th International Symposium on Dental Morphology. Berlin, C&M Brunne Gbr, 1995. pp.428-32.
Bjerklin, K.; Kurol, J. & Valentin, J. Ectopic eruption of maxillary first permanent molars and association with other tooth and developmental disturbances. Eur. J. Orthod., 14(5):369-75, 1992.
Bruce, C.; Manning-Cox, G.; Stanback-Fryer, C.; Bank, K. & Gilliam, M. A radiographic survey of dental anomalies in Black pediatric patients. NDA J., 45(1):6-13, 1994.
Hoffmeister, H. Zwillings und Familienbefundezur Manifestations-schawankung bei Oligodontie und Hypodontie und zu verwandten Erscheinungen. Fortschritt der Kieferorthopadie, 36:18-33, 1975.
Hoffmeister, H. Mikrosyptome als Hinweis aur vererbte Unterzahl, Uberzahl und Verlagerung von Zahnen. Deutsche zahnarztliche Zeitschrift, 32:551-61, 1977.
Hoffmeister, H. Die unterminierend Resorption der zweiten Milchmolaren durch die 6-Jahr Molaren als Mikrosymptom der vererbten Storanfalligkeit der Gebissbildung. Schweiz monatsschr zahnmed, 95:151-4, 1985.
Kotsomitis, N. & Freer, T. J. Inherited dental anomalies and abnormalities. ASDC J. Dent. Child., 64(6):405-8, 1997.
Lai, P. Y. & Seow, W. K. A controlled study of the association of various dental anomalies with hypodontia of permanent teeth. Pediatr. Dent., 11(4):291-6, 1989.
Rubenstein, L. K.; Lindauer, S. J.; Isaacson, R. J. & Germane, N. Development of supernumerary premolars in an orthodontic population. Oral Surg. Oral Med. Oral Pathol., 71(3):392-5, 1991.
Salzano, F. M. Genetica Odontologica. Sao Paulo, Editora da Universidade de Sao Paulo, 1982.
Seow, W. K. & Lai, P. Y. Association of taurodontism with hypodontia: a controlled study. Pediatr. Dent., 11(3):21-49, 1989.
Umweni, A. A. & Ojo, M. A. The frequency of tooth transposition in Nigerians, its possible aetiologic factorsand clinical implications. J. Dent. Assoc. S. Afr., 52(9):551-4, 1997.
Umweni, A. A. & Osunbor, G. E. Non-syndrome multiple supernumerary teeth in Nigerians. Odontostomatol Trop., 25(99):43-8, 2002.
Prof. Dr. Reinaldo Azoubel
Departamento de Pos-graduacao
Faculdade de Medicina de Sao Jose do Rio Preto
Av. Brigadeiro Faria Lima, 5416
Vila Sao Pedro
Phone: (17) 3201-5700
*,** Miziara, R. C.; * Mendes-Junior, C. T.; * Wiezel, C. E. V.; * Simoes, A. L.; **Scuoteguazza, J. A. C. & *** Azoubel, R.
* Departamento de Geneica, Faculdade de Medicina de Ribeirao Preto, Ribeirao Preto, Universidade de Sao Paulo, SP, Brazil.
** Curso de Odontologia das Faculdades Unificadas da Fundacao Educacional de Barretos, Barretos, SP, Brazil.
*** Departamento de Pos-graduacao da Faculdade de Medicina de Sao Jose do Rio Preto, SP, Brazil.
Research supported by Fundacao Educacional de Barretos, FEB
Table I. Occurrence frequency of seven dental anomalies in 172 individuals analyzed. Dental Affected patients anomalies (from a total 172 individuals) Freq. 1 2 3 4 5 6 7 8 9 10 11 Second X X 0.012 pre-molar agenesis Supra X X X X 0.023 numerous teeth Upper canine ectopic eruption First molar X 0.006 ectopic eruption Lower first X 0.006 molar infra-ochlesis Enamel X X X X X X 0.035 hypoplasia Reduced size X X 0.012 upper side incisive Table II. Probability of association among the pairs of anomalies analyzed, obtained by the Fisher exact test. The significant values are in bold. (a)- second pre-molar agenesis; (b)- supra numerous teeth; (c)- upper canine ectopic eruption; (d)- first molar ectopic eruption; (e)- lower first molar infra-ochlesis; (f)- enamel hypoplasia; g- reduced size upper side incisive. (a) SPA (b) SNT (c) UCEE (d) FMEE (e) LFMI (f) EH SNT 0,954 UCEE 1,000 1,000 FMEE 0,012 0,977 1,000 LFMI 0,012 0,977 1,000 0,994 EH 0,069 0,866 1,000 0,034 0,965 (g) RSUSI 0,023 0,046 1,000 0,988 0,012 0,931