Maria Ivete Bolzan Rockenbach

Response to Intracanal Medication in Immature Teeth with Pulp Necrosis: An Experimental Model in Rat Molars

INTRODUCTION The present study aimed at developing an experimental model in rat molars for evaluating treatment strategies in necrotic immature teeth. METHODS To define the periods to be adopted in the experimental procedures and to confirm induction of periapical lesions and interruption of root embryogenesis, the left lower first molars of 4-weeks-old Wistar rats underwent pulpectomy and were left open to the oral environment. Comparisons with the right lower first molars (vital teeth) were performed in animals with ages of 7, 10, 13, and 16 weeks. In another group of animals the teeth were left open for 3 weeks, and then interventions for disinfection including the use of an antibiotic paste were carried out. Root formation was then assessed after 3 and 6 weeks on the basis of radiographic and histologic evaluation. RESULTS Vital teeth showed increase of root length and hard tissue thickness throughout the experimental periods. On the other hand, induction of necrosis arrested root formation. Teeth subjected to disinfection with sodium hypochlorite associated with the triple antibiotic paste showed significant reduction of periapical lesions, gain in root length, and increased wall thickness compared with the control (P < .05). CONCLUSIONS The root canal disinfection protocol used was able to reduce periapical lesion size and improve root development. The experimental model presented should contribute to studies that aim at improving therapeutic strategies for necrotic immature teeth by using a rat model.

Salivary flow rate, pH, and concentrations of calcium, phosphate, and sIgA in Brazilian pregnant and non-pregnant women

BackgroundStudies on salivary variables and pregnancy in Latin America are scarce. This study aimed to compare salivary flow rate, pH, and concentrations of calcium, phosphate, and sIgA of unstimulated whole saliva in pregnant and non-pregnant Brazilians.MethodsCross-sectional study. Sample was composed by 22 pregnant and 22 non-pregnant women attending the Obstetrics and Gynecology Clinics, São Lucas Hospital, in Porto Alegre city, South region of Brazil. Unstimulated whole saliva was collected to determine salivary flow rate, pH, and biochemical composition. Data were analyzed by Student t test and ANCOVA (two-tailed α = 0.05).ResultsNo difference was found for salivary flow rates and concentrations of total calcium and phosphate between pregnant and non-pregnant women (p > 0.05). Pregnant women had lower pH (6.7) than non-pregnant women (7.5) (p < 0.001), but higher sIgA level (118.9 mg/L) than the latter (90.1 mg/L) (p = 0.026).ConclusionSome of the tested variables of unstimulated whole saliva were different between pregnant and non-pregnant Brazilians in this sample. Overall, the values of the tested salivary parameters were within the range of international references of normality.

Validity of 2D lateral cephalometry in orthodontics: a systematic review

Lateral cephalometric radiography is commonly used as a standard tool in orthodontic assessment and treatment planning. The aim of this study was to evaluate the available scientific literature and existing evidence for the validation of using lateral cephalometric imaging for orthodontic treatment planning. The secondary objective was to determine the accuracy and reliability of this technique. We did not attempt to evaluate the value of this radiographic technique for other purposes. A literature search was performed using specific keywords on electronic databases: Ovid MEDLINE, Scopus and Web of Science. Two reviewers selected relevant articles, corresponding to predetermined inclusion criteria. The electronic search was followed by a hand search of the reference lists of relevant papers. Two reviewers assessed the level of evidence of relevant publications as high, moderate or low. Based on this, the evidence grade for diagnostic efficacy was rated as strong, moderately strong, limited or insufficient. The initial search revealed 784 articles listed in MEDLINE (Ovid), 1,034 in Scopus and 264 articles in the Web of Science. Only 17 articles met the inclusion criteria and were selected for qualitative synthesis. Results showed seven studies on the role of cephalometry in orthodontic treatment planning, eight concerning cephalometric measurements and landmark identification and two on cephalometric analysis. It is surprising that, notwithstanding the 968 articles published in peer-reviewed journals, scientific evidence on the usefulness of this radiographic technique in orthodontics is still lacking, with contradictory results. More rigorous research on a larger study population should be performed to achieve full evidence on this topic.

Evaluation of mandibular implant sites: correlation between panoramic and linear tomography

The reliability of the linear tomography and panoramic radiography made with X-ray equipment was evaluated (Vera View Scope X-600; Morita). The sample was composed of 20 dry human hemimandibles, in which the area selected for analysis was 1.5 cm distal from the limit set before the mental foramen. Four measurements were made. The images obtained were drawn on acetate paper and the hemimandibles cut at the demarcated area. The measurements were made using a digital electronic pachymeter. The values found for the radiographic images were compared to those obtained in the mandibular specimens and submitted to statistical evaluation by the Wilcoxon test. It was concluded that both techniques were reliable for the accomplishment of vertical linear measurements in the selected area. However, a 2.0 mm safety margin is recommended.

Optimization of dental CBCT exposures through mAs reduction

OBJECTIVES To investigate the effect of tube current-exposure time (mAs) reduction on clinical and technical image quality for different CBCT scanners, and to determine preliminary minimally acceptable values for the mAs and contrast-to-noise ratio (CNR) in CBCT. METHODS A polymethyl methacrylate (PMMA) phantom and an anthropomorphic skull phantom, containing a human skeleton embedded in polyurethane, were scanned using four CBCT devices, including seven exposure protocols. For all protocols, the mAs was varied within the selectable range. Using the PMMA phantom, the CNRAIR was measured and corrected for voxel size. Eight axial slices and one coronal slice showing various anatomical landmarks were selected for each CBCT scan of the skull phantom. The slices were presented to six dentomaxillofacial radiologists, providing scores for various anatomical and diagnostic parameters. RESULTS A hyperbolic relationship was seen between CNRAIR and mAs. Similarly, a gradual reduction in clinical image quality was seen at lower mAs values; however, for several protocols, image quality remained acceptable for a moderate or large mAs reduction compared with the standard exposure setting, depending on the clinical application. The relationship between mAs, CNRAIR and observer scores was different for each CBCT device. Minimally acceptable values for mAs were between 9 and 70, depending on the criterion and clinical application. CONCLUSIONS Although noise increased at a lower mAs, clinical image quality often remained acceptable at exposure levels below the manufacturers recommended setting, for certain patient groups. Currently, it is not possible to determine minimally acceptable values for image quality that are applicable to multiple CBCT models.

Accuracy of linear measurements before and after digitizing periapical and panoramic radiography images

The aim of this study was to evaluate the accuracy of linear measurements made on conventional and digitized periapical and panoramic radiographic images of dry human hemi-mandibles. Images from the posterior region of 22 dry human hemi-mandibles were obtained by conventional panoramic and periapical radiography technique. Using a digital caliper, 3 vertical measurements were marked directly on the dry hemi-mandibles (reference measurements) as well as on the tracing from the conventional radiographic images of the specimens made onto acetate paper sheet: Distance 1: between the upper limit of the alveolar ridge and the lower limit at the mandible base; Distance 2: between the upper limit of the alveolar ridge and the upper limit of the mandibular canal; Distance 3: between the lower limit of the mandibular canal and the lower limit of the mandible base. Next, the radiographs were digitized and the three measurements were made on the digital images using UTHSCSA Image Tool software. Data were analyzed statistically by one-way ANOVA (α=0.05). There was no statistically significant differences (p>0.05) between periapical and panoramic radiographs or between the measurements recorded using the digital caliper and UTHSCSA software compared with dry mandible specimens for Distances 1 (p=0.783), 2 (p=0.986) and 3 (p=0.129). In conclusion, the radiographic techniques evaluated in this study are reliable for vertical bone measurements on selected areas and the UTHSCA Image Tool software is an appropriate measurement method.

Projection of the oblique line in periapical radiographs of mandibular molars

PURPOSE: To identify and quantify the frequency of the projection of the oblique line over the alveolar crests of the mandibular molars in periapical radiographs. METHODS: Five hundred periapical radiographs of the mandibular molar region were selected and evaluated for the presence or absence of the oblique line. When present, its interference on the image of the alveolar crest of the mandibular molars was analyzed. The data obtained was expressed as a percentage of the overlap of the oblique line to the alveolar crests of the mandibular molars. RESULTS: The oblique line was observed in 363 out of the 500 periapical radiographs (72.6%). Out of the 363, 308 (84.8%) showed an overlap of the oblique line over the alveolar crests. However, 55 radiographs (15.1%) did not show such interference. Of the radiographs showing an overlap (308), the incidence of an overlap was 64.6% at a single site (199 radiographs), 33.4% at two sites (103 radiographs), and 1.9% (6 radiographs) at three sites. CONCLUSION: The overlap of the oblique line over the image of the alveolar crests in the mandibular molar region was observed in a significant portion of the total sample.

Effects of radio-opacifier addition in dental impression material.

OBJECTIVE The aim of this in vitro study was to determine the effects of barium sulfate addition in two dental impression materials previously proved as radiolucent. MATERIALS AND METHODS An irreversible hydrocolloid (IH) and polyether (PE) were tested for optical density, linear dimension stability and detail reproduction. STATISTICAL ANALYSIS USED The optical density data were submitted to Kolmogorov-Smirnov normality test and compared with two-way ANOVA and Tukey (alpha=0.05). RESULTS The results of optical density (pixel) were: IH control 45.24 f (+/-7.6), PE control 54.93 e (+/-4.45), PE 5Wt% 60.43 d (+/-6.27), IH 1Wt% 61.54 cd (+/-5.3), PE 1Wt% 66.9 bc (+/-5.05), IH 5Wt% 67.17 b (+/-6.01), PE 10Wt% 84.55 a (+/-5.14), IH 10Wt% 85.33 a (+/-5.53). On detail reproduction, polyether control was able to copy the 6 microm line. Adding 1 or 5Wt% of barium sulfate have not change this characteristic. For the irreversible hydrocolloid, the control group was able to copy a line with 14 microm, however, adding 1Wt% barium sulfate, the capability decreased to 22 microm. Adding barium sulfate in the polyether promoted an increase in between the copied lines, for the control, the average distance was 931.6 microm, 936 microm to 1Wt% and 954.5 microm to 5 Wt%. For the IH, the control presented 975 microm in comparison to 987.25 microm for 1 Wt% samples. CONCLUSION The addition of barium sulfate was capable of increasing significantly the optical density of tested material, have changed the linear dimension stability, however, have not interfered in detail reproduction only for PE.

Conduta do cirurgião-dentista frente à necessidade de exodontia em pacientes irradiados na região da cabeça e pescoço

O presente estudo tem por objetivo, com base na literatura vigente, enfatizar aspectos importantes relacionados a realizacao de exodontia em pacientes submetidos a radioterapia na regiao da cabeca e pescoco, visando alertar o clinico quanto ao risco de ocorrencia de osteorradionecrose (ORN). Percebe-se que o osso irradiado responde de forma peculiar a infeccao, em virtude da sua condicao de hipoxia, hipocelularidade e hipovascularidade. Assim, exodontias durante e apos o tratamento radioterapico sao contraindicadas. Na presenca de envolvimento pulpar, a terapia endodontica e considerada a primeira opcao de tratamento. Quando esta terapia nao for possivel, opta-se pela exodontia, que devera ser conduzida, pelo menos, tres semanas antes do inicio da radioterapia.