Rívea Inês Ferreira

Assessment of enamel demineralization using conventional, digital, and digitized radiography

This experimental research aimed at evaluating the accuracy of enamel demineralization detection using conventional, digital, and digitized radiographs, as well as to compare radiographs and logarithmically contrast-enhanced subtraction images. Enamel subsurface demineralization was induced on one of the approximal surfaces of 49 sound third molars. Standardized radiographs of the teeth were taken prior to and after the demineralization phase with three digital systems--CygnusRay MPS, DenOptix and DIGORA--and InSight film. Three radiologists interpreted the pairs of conventional, digital, and digitized radiographs in two different occasions. Logarithmically contrast-enhanced subtraction images were examined by a fourth radiologist only once. Radiographic diagnosis was validated by cross-sectional microhardness profiling in the test areas of the approximal surfaces. Accuracy was estimated by Receiver Operating Characteristic (ROC) analysis. Chi-square test, at a significance level of 5%, was used to compare the areas under the ROC curves (A(z)) calculated for the different imaging modalities. Concerning the radiographs, the DenOptix system (A(z) = 0.91) and conventional radiographs (A(z) = 0.90) presented the highest accuracy values compared with the other three radiographic modalities. However, logarithmically contrast-enhanced subtraction images (A(z) = 0.98) were significantly more accurate than conventional, digital, and digitized radiographs (p = 0.0000). It can be concluded that the DenOptix system and conventional radiographs provide better performance for diagnosing enamel subsurface demineralization. Logarithmic subtraction significantly improves radiographic detection.

Image quality in digital radiographic systems

The aim of the present study was to evaluate the image quality of four direct digital radiographic systems. Radiographs were made of the maxillary central incisor and mandibular left molar regions of a dry skull, and an aluminum step-wedge. The X-ray generator operated at 10 mA. 60 and 70 kVp, and images were acquired with 3, 5, 8, 12, 24 and 48 exposure pulses. Six well-trained observers classified the images by means of scores from 1 to 3. Collected data were submitted to nonparametric statistical analysis using Fishers exact test. Statistical analysis showed significant differences (p < 0.01) in image quality with the four systems. Based on the results, it was possible to conclude that: 1) all of the digital systems presented good performance in producing acceptable images for diagnosis, if the exposures of the step-wedge and the maxillary central incisor region were made at 5 pulses, as well as at 8 pulses for the mandibular left molar region, selecting 60 or 70kVp; 2) higher percentages of acceptable images were obtained with the administration of lower radiation doses in CCD-sensors (charge-coupled device); 3) the Storage Phosphor systems produced acceptable images at a large range of exposure settings, that included low, intermediate and high radiation doses.

Image quality in partially erased DenOptix® storage phosphor plates

This study aimed at investigating the effect of the partial erasing of DenOptix system storage phosphor plates on the image quality of digital radiographs. Standardized digital radiographs were acquired of a phantom mandible, using size 2 intraoral DenOptix storage phosphor plates (n = 10). Subsequently, the active areas of the plates were placed in a viewing box with a constant light intensity of 1,700 lux for 130 seconds to achieve complete erasing (control plate), as well as for 0, 5, 10, 15, 20, 25, 34, 66, and 98 seconds, to compose the experimental group of partially erased plates. The same exposure settings were repeated using the control and experimental plates, which were scanned at a resolution of 300 dpi. Five radiologists independently examined the pairs of digital radiographs obtained with the control and partially erased plates, in random order, and indicated the best image for oral diagnosis. Cochran-Mantel-Haenszels chi-square test, at a significance level of 5%, was used to compare the percentages of superior quality images in each combination of control and partially erased plates, subjectively assessed. No significant differences were found between radiographic images acquired with control and partially erased plates, except for the combination of 0 second (30%) versus 130 seconds (70%), p = 0.0047. It can be concluded that, under adequate light intensity conditions, erasing intraoral DenOptix storage phosphor plates may require time intervals of as little as 5 seconds.

Effect of low-dose electron radiation on rat skin wound healing

The aim of this study was to assess the effect of low-dose electron irradiation on morphological features of the wound healing process in rat skin. Surgical wounds were inflicted with a 2.3 x 1.4 cm template on 84 male rats that were assigned to 4 groups: IG1, immediately irradiated; IG2, irradiated 3 days after inflicting the wound; CG1 and CG2, control groups. Rats in IG1 and IG2 groups had their wounds exposed to 1 Gy of 6 MeV electron beam radiation, immediately after surgery and on the third postoperative day, respectively. Qualitative and histophotometric evaluations of tissue repair structures were carried out. Data were analyzed by ANOVA and Tukeys test (alpha = 0.05) and regression analysis. The repair process was delayed since the first sacrifice time in both irradiated groups, but in IG1, wound healing was closer to that of CG1; whereas in IG2, the delay was more pronounced. Based on the histological findings, it is possible to conclude that a low-dose of electron radiation delayed tissue repair in rat skin. The delay was longer in the skin irradiated 3 days after the beginning of tissue repair. However, the low-energy electron irradiation did not prevent wound healing.

Association between nonnutritive sucking habits and anterior open bite in the deciduous dentition of Japanese-Brazilians

OBJECTIVE: Assess the association between nonnutritive sucking habits and anterior open bite in the deciduous dentition of Japanese-Brazilian children. METHODS: 410 children of Japanese origin were assessed, 206 boys and 204 girls, between 2 and 6 years of age, in schools in Sao Paulo State, Brazil. Questionnaires concerning their nonnutritive sucking habits were sent to their legal guardians. Chi-square tests (p<0.05) were applied to assess the association between nonnutritive sucking habits and anterior open bite, and the logistic regression test to obtain the relative risk. RESULTS: The prevalence of sucking habits found in the sample was of 44.6% and for the anterior open bite, 4.4%. There was a statistically significant association between anterior open bite and sucking habits (O.R.=10.77), persistence of sucking habits from 2 to 4 years old (O.R.=22.06), and the persistence of sucking habits from 4 to 6 years old (O.R.=17.31). As for the interruption period of the habit, the group that had interrupted the habit for a period equal or inferior to six months showed an increased prevalence of open bite compared to the group without this habit or in which the habit was interrupted for more than six months. CONCLUSION: Japanese-Brazilian children that had sucking habits have greater chance of acquiring anterior open bite in the deciduous dentition.

Orthodontic retainers: analysis of prescriptions sent to laboratories

OBJECTIVE: To investigate the most commonly fabricated orthodontic retainers. METHODS: Information on the type and amount of maxillary and mandibular retainers produced in a three-month period was collected from six laboratories in the cities of Sao Paulo, Maua and Guarulhos - Brazil. The retainers were grouped according to the total production. For the maxillary arch, the groups were: 1S - Begg retainer, 2S - Hawley retainer, 3S - transpalatal arch retainer, 4S - buccal resin-arch retainer and 5S - vacuum-formed retainer, Planas appliance, bonded lingual retainer and V-loop bonded lingual retainer. The groups relative to the mandibular arch were: 1I - 3-3 bonded lingual retainer (canine to canine), 2I - Hawley retainer and V-loop bonded lingual retainer, 3I - Begg retainer, 4I - buccal resin-arch retainer, vacuum-formed retainer and Planas appliance. The data were presented in box plots. Groups were compared using the Students-t test with Bonferroni correction. RESULTS: The average of maxillary appliances fabricated ranged from 189.5 (1S) to 3.95 (5S). There were significant differences between groups 1S versus 5S and 2S versus 5S (p < 0.0001). Mean values for the mandibular retainers ranged from 55.3 (1I) to 4.2 (4I). Significant difference was observed between groups 2I and 4I (p < 0.0001). CONCLUSIONS: For the maxillary arch, the most requested retainers were Begg and Hawley retainers. Regarding the mandibular arch, bonded lingual retainers and Hawley retainer were the most frequent ones.

Avaliação comparativa do espaçamento anterior em nipo-brasileiros e leucodermas, na dentição decídua

OBJECTIVE: To carry out a comparative evaluation of the prevalence of anterior spacing characteristics in Japanese-Brazilian and white children in primary dentition. METHODS: Two selected samples of children aged 2-6 years were: 405 Japanese-Brazilians from 36 schools in the State of Sao Paulo and 510 white children from 11 public institutions in Sao Paulo city. The spacing features in the maxillary and mandibular arches were assigned to four categories: generalized spacing; only primate spaces; no spacing; and crowding. Logistic regression was used to analyze the effect of age, gender and ethnic group on the prevalence of the occlusal characteristics (α=0.05). RESULTS: In Japanese-Brazilians, generalized spacing was the most prevalent trait in the maxillary (46.2%) and mandibular (53.3%) arches. The frequency of primate spaces was higher in the maxillary arch (28.2% versus 15.3%). Concerning no spacing (21.7-26.4%) and crowding (4.0-4.9%), the variation between arches was relatively small. In white children, no spacing and exclusive presence of primate spaces showed distributions similar to that observed in Japanese-Brazilians. Generalized spacing was diagnosed in approximately 50% of the arches. Crowding prevalence was higher in the mandibular arch (12.8% versus 3.9%). The regression model adjusted for crowding prevalence was the only significant one. Only racial factor was significant (p<0.001). CONCLUSION: It may be suggested that anterior spacing features in primary dentition would not be influenced by age or gender. Nevertheless, white children would have 2.8 times more chances of presenting crowding in the mandibular arch, in comparison with Japanese-Brazilians.

Correlação entre as medidas coronárias e a espessura do esmalte proximal em primeiros pré-molares inferiores

Esta pesquisa teve por finalidade analisar as correlacoes entre as dimensoes coronarias, mesio-distal, cervico-oclusal e vestibulo-lingual, e a espessura de esmalte proximal em pre-molares inferiores. Foram selecionados quarenta primeiros pre-molares inferiores, vinte direitos e vinte esquerdos. As medidas coronarias foram determinadas com paquimetro digital. Aferiu-se a espessura do esmalte proximal em seccoes dos dentes por meio de um perfilometro. As diferencas entre as medias das dimensoes coronarias e da espessura do esmalte foram avaliadas pelo teste t de student (p<0,05). A correlacao entre as diversas grandezas foi analisada pelos testes de Spearman e Pearson. As dimensoes mesio-distal, cervico-oclusal e vestibulo-lingual foram de 7,74mm e 7,57mm; 9,07mm e 8,99mm; e 7,97mm e 8,09mm, para os lados direito e esquerdo, respectivamente. A espessura do esmalte nas faces mesiais foi de 1,025mm para o lado direito e 1,063mm, para o esquerdo. Os valores correspondentes nas faces distais foram de 1,229mm e 1,293mm. Nao houve diferencas significativas entre as medidas dos lados direito e esquerdo. Verificaram-se correlacoes entre as dimensoes mesio-distal e vestibulo-lingual, bem como entre as espessuras de esmalte mesial e distal, em ambos os lados. Desse modo, a altura cervico-oclusal superou as medidas mesio-distal e vestibulo-lingual, indicando que as coroas dos primeiros pre-molares inferiores apresentaram maior dimensao ocluso-apical. A espessura do esmalte foi maior nas faces distais. As dimensoes mesio-distal e vestibulo-lingual e as espessuras do esmalte proximal, dos lados direito e esquerdo, demonstraram uma relacao diretamente proporcional.