ABSTRACT
BACKGROUND: The present study aimed to assess the frequency and variation of 13 nonmetric dental crown traits (NDCT) in permanent and primary molars in German orthodontic patients. METHODS: Dental records from orthodontic patients were screened and evaluated. First and second permanent and primary upper and lower molars (from left and right sides) were assessed. Teeth with cavitated dental caries, occlusal wear, restorations and obvious dental deformities were not evaluated. The NDCT for permanent molars were identified and scored according to the odontoscopic system developed by Arizona State University Dental Anthropology System (ASUDAS). The NDCT for primary molars were identified and scored according to ASUDAS, Hanihara's method and Sciulli's method. The χ2 test was used to investigate side preference and sexual dimorphism at a significance level of pâ¯≤ 0.050. RESULTS: A total of 163 orthodontic patients (82 males and 81 females) aged 8-14 years were included. A sexual dimorphism was observed for the hypocone in first upper permanent molar (pâ¯= 0.041). The protostylid was observed in lower permanent molars (range 2.1-10%). Males presented more hypoconulid than females (pâ¯= 0.019). Only females presented the distal trigonid crest in lower first permanent molars (pâ¯= 0.002). The most common groove pattern in primary molars was Y; male presented more Y grade than females in the lower second primary molar (pâ¯= 0.039). Asymmetry was observed in some traits, ranging from 0 to 100%. CONCLUSION: The present study showed the frequency of NDCT of molars in German orthodontic patients and demonstrated that some traits present sexual dimorphism.
ABSTRACT
BACKGROUND: This study aimed to evaluate the prevalence of retained primary teeth (RPT) associated with delayed permanent tooth eruption and the factors associated with this condition in German children. METHODS: This is a cross-sectional retrospective study that evaluated panoramic radiographs from orthodontic patients. The diagnosis of RPT was established according to Nolla developmental stage. The primary tooth was considered retained when its successor permanent tooth was in Nolla stage 8, 9, or 10. Statistical analysis was performed with an α of 5% (pâ¯< 0.05). RESULTS: A total of 102 children (48 girls and 54 boys), and 574 primary teeth and their respective permanent successor teeth were evaluated. We classified 192 teeth as RPT. Sixty-one (59.8%) children presented one or more RPT. Gender was not significantly different between RPT and control teeth (pâ¯= 0.838; odds ratioâ¯0.95, confidence interval 95%â¯0.44-2.16). In the majority of the RPT cases (68.7%), no clear cause to explain the prolonged retention was identified. The pathological problems most commonly observed with RPT were dental fillings (19.3%), followed by dental caries (4.6%), and ectopic tooth eruption (2.1%). CONCLUSIONS: The incidence of RPT associated with delayed permanent tooth eruption in German children was high and the most common pathological condition associated with RPT was dental caries.
ABSTRACT
El objetivo de este trabajo "in vitro" fue evaluar la resistencia de unión de dos sistemas adhesivos utilizando el ensayo de microtracción, variando el tipo de substrato dentinario. Fueron utilizados 32 terceros molares humanos recientemente extraídos, los cuales fueron divididos en cuatro grupos de acuerdo con la orientación de los túbulos dentinarios (paralelos o perpendiculares) y con el tipo de sistema adhesivo utilizado (convencional o auto-acondicionante). Además de evaluar la resistencia de unión, todas las muestras fueron examinadas visualmente para determinar el tipo de fractura. Posteriormente, los resultados fueron sometidos a análisis estadística, permitiendo concluir que los adhesivos autoacondicionantes poseen un mejor comportamiento, mostrando mayor resistencia de unión a la dentina cuando los túbulos dentinarios están expuestos paralelamente al largo del eje del elemento dentario. Sin embargo cuando los túbulos dentinarios están perpendiculares al eje del diente, los sistemas adhesivos convencional y autoacondicionantes poseen resistencia adhesiva semejante. En cuanto al tipo de fractura de los cuerpos de prueba, las fallas adhesivas son predominantes, independiente del sistema adhesivo utilizado y del tipo de substrato dental
The aim of this in vitro study was to evaluate the microtensile bond strength, for two adhesive systems, varying the dentin substrate. Thirty-two recently extracted third molars human were used, and divided in four groups according to the dentin tubules orientation (parallels and perpendiculars) and the adhesive systems (total-etching and self-etching). The specimens were examined by optical microscope for determined the fracture type. After, the statistical analysis was evaluated, allowing to conclude that the self-etching adhesive systems showed better behavior and greater bond strength for dental substrate, when the dentin tubules were parallel exposited to dental axis. Nevertheless, when the dentin tubules were perpendiculars, the total-etching and self-etching adhesive systems showed similar statistical bond strength values. For the fracture type of the specimens, adhesive fractures were predominant, independent of the adhesive systems and the type of dental substrate used
