Criteria for early diagnosis of third molar agenesis: a retrospective radiographic study.

OBJECTIVE: To explore the association between chronological, dental and skeletal ages and early diagnosis of third molars agenesis. MATERIAL AND METHODS: This retrospective radiographic study comprised a sample of 282 Portuguese patients (122 males and 160 females) who sought orthodontic treatment between 2007 and 2018. Each participant had panoramic and lateral cephalometric radiographs performed before and after the age of 14 years. The chronological age was categorized into three intervals between 11.0 and 13.11 years of age. The full eruption of the four-second molars was used as a criterion in determining dental age. Skeletal age was verified by the vertebral maturation method. The diagnosis of agenesis of third molars was initially performed by observation of the initial panoramic radiography undertaken before the age of 14 years. Subsequently, the diagnosis of agenesis of third molars was confirmed by visualizing the second panoramic radiography, obtained after the age of 14 years. The association between the accuracy of the diagnosis and the chronological, dental and skeletal ages was evaluated using the chi-square test, at a 5% significance level. RESULTS: No significant association between chronological age and alterations in the diagnosis of third molar agenesis was identified. However, there was a significant association between third molar agenesis and both dental age (p<0.001) and skeletal age (p=0.006). CONCLUSION: The eruption of the four-second molars and the peak of growth could be considered as criteria for early diagnosis of third molar agenesis, whereas chronological age is not a reliable diagnostic indicator.

Criteria for early diagnosis of third molar agenesis: a retrospective radiographic study

ABSTRACT Objective: To explore the association between chronological, dental and skeletal ages and early diagnosis of third molars agenesis. Material and Methods: This retrospective radiographic study comprised a sample of 282 Portuguese patients (122 males and 160 females) who sought orthodontic treatment between 2007 and 2018. Each participant had panoramic and lateral cephalometric radiographs performed before and after the age of 14 years. The chronological age was categorized into three intervals between 11.0 and 13.11 years of age. The full eruption of the four-second molars was used as a criterion in determining dental age. Skeletal age was verified by the vertebral maturation method. The diagnosis of agenesis of third molars was initially performed by observation of the initial panoramic radiography undertaken before the age of 14 years. Subsequently, the diagnosis of agenesis of third molars was confirmed by visualizing the second panoramic radiography, obtained after the age of 14 years. The association between the accuracy of the diagnosis and the chronological, dental and skeletal ages was evaluated using the chi-square test, at a 5% significance level. Results: No significant association between chronological age and alterations in the diagnosis of third molar agenesis was identified. However, there was a significant association between third molar agenesis and both dental age (p<0.001) and skeletal age (p=0.006). Conclusion: The eruption of the four-second molars and the peak of growth could be considered as criteria for early diagnosis of third molar agenesis, whereas chronological age is not a reliable diagnostic indicator.

RESUMO Objetivo: Explorar a associação entre as idades cronológica, dentária e esquelética e o diagnóstico precoce da agenesia dos terceiros molares. Material e Métodos: Este estudo radiográfico retrospectivo compreendeu uma amostra de 282 pacientes portugueses (122 homens e 160 mulheres) que procuraram tratamento ortodôntico entre 2007 e 2018. Cada participante tinha radiografias panorâmicas e cefalométricas laterais realizadas antes e depois dos 14 anos de idade. A idade cronológica foi categorizada em três intervalos entre 11,0 e 13,11 anos de idade. A erupção completa dos quatro segundos molares foi usada como critério para determinar a idade dentária. A idade esquelética foi verificada pelo método de maturação das vértebras cervicais. O diagnóstico de agenesia de terceiros molares foi inicialmente realizado pela observação da radiografia panorâmica inicial, realizada antes dos 14 anos de idade. Posteriormente, o diagnóstico de agenesia de terceiros molares foi confirmado pela visualização da segunda radiografia panorâmica, obtida após os 14 anos de idade. A associação entre a acurácia do diagnóstico e as idades cronológica, dentária e esquelética foi avaliada por meio do teste qui-quadrado, com nível de significância de 5%. Resultados: Não foi identificada associação significativa entre idade cronológica e alterações no diagnóstico de agenesia de terceiros molares. No entanto, houve associação significativa entre agenesia de terceiro molar e idade dentária (p<0,001) e idade óssea (p=0,006). Conclusão: A erupção dos quatro segundos molares e o pico de crescimento podem ser considerados critérios para o diagnóstico precoce da agenesia do terceiro molar, enquanto a idade cronológica não é um indicador diagnóstico confiável.

Cervical vertebral maturation and its relationship to circum-pubertal phases of the dentition in a cohort of Portuguese individuals.

BACKGROUND: To explore the relationship between individual skeletal maturity as assessed by Cervical Vertebral Maturity method (CVM), circum-pubertal phases of the dentition (early mixed, intermediate mixed, late mixed and early permanent) and chronlogical age in a cohort of Portuguese individuals. MATERIAL AND METHODS: This was a retrospective cross-sectional study. The sample comprised 300 Caucasian Portuguese subjects aged 6 to 16 years, (137 boys and 163 girls). All the participants had good quality panoramic and lateral cephalometric radiographs. Subject skeletal maturity was evaluated using the CVM method. Dental age evaluation was determined by using panoramic radiographs and dental casts. Descriptive statistics (absolute and relative frequencies) and percentages were obtained for the prevalence of the CVM stages in the various phases of the dentition and for the different ages for each of males and females. RESULTS: Prepubertal stage 1 (CS1) was predominently observed in the early mixed dentition phase followed by the intermediate mixed dentition phase. While, the CS1 stage was found in all the other phases of tooth development. There was a wide distribution of all CVM stages in the late mixed dentition and early permanent dentition phases. While, the CS3 stage was predominantly present in both the late mixed dentition and in the early permanent dentition phases. Moreover, the chronological age did not seem to be an accurate indicator in differentiating between the pre-pubertal and the pubertal growth spurt stages. CONCLUSIONS: Early mixed dentition phase could determine with a high accuracy the prepubertal skeletal maturity stage (CS1), Furthermore, the chronological age did not seem to be an accurate indicator in differentiating between the pre-pubertal and the pubertal growth spurt stages. Key words:Cervical vertebrae, cephalometric, panoramic, tooth calcification, portuguese.

Bolton ratios in Portuguese subjects among different malocclusion groups.

BACKGROUND: Several methods have been described to estimate inter-arch tooth size relationship, such as Bolton's ratios. The aims of this study were to verify the validity of Bolton indexes in a sample of untreated Portuguese subjects based on Angle classification and to evaluate the gender difference. MATERIAL AND METHODS: 168 pre-treatment dental casts of orthodontics Portuguese subjects (59 males and 109 females) with different occlusions were used, which were selected randomly from 541 consecutively treated orthodontic patients. The mesiodistal widths from first molar to first molar were measured on each pre-treatment cast to the nearest 0.01 mm using digital caliper, and Bolton's anterior and overall ratios were calculated. Descriptive statistics as mean, standard deviation and range were calculated. Moreover, the results were compared to Bolton's ratios and differences based on gender and occlusion groups were evaluated by statistical inference methods. RESULTS: The results reveal that the mean values, standard deviation and range were larger than Bolton's in normal occlusion group (78.3±3.5% in anterior ratio and 92.1±2.2% in overall ratio) and there were no differences between genders (p >0.05). Class I (anterior and overall ratios, p=0.001 and p<0.001, respectively), Class II/2 (anterior ratio, p=0.032) and Class III (overall ratio, p=0.041) were significantly different from Bolton's reference data. CONCLUSIONS: The results showed no differences between gender and no difference between normal occlusion and malocclusion groups. Moreover, in normal occlusion group, the anterior and overall tooth size ratios was equivalent to the original Bolton's ratios, although the mean and standard deviation were large. Key words:Bolton anterior and overall ratios, normal occlusion, malocclusion, portuguese population.