Cone-Beam Computed Tomography and Radiographs in Dentistry: Aspects Related to Radiation Dose

Introduction. The aim of this study was to discuss the radiation doses associated with plain radiographs, cone-beam computed tomography (CBCT), and conventional computed tomography (CT) in dentistry, with a special focus on orthodontics. Methods. A systematic search for articles was realized by MEDLINE from 1997–March 2011. Results. Twenty-seven articles met the established criteria. The data of these papers were grouped in a table and discussed. Conclusions. Increases in kV, mA, exposure time, and field of view (FOV) increase the radiation dose. The dose for CT is greater than other modalities. When the full-mouth series (FMX) is performed with round collimation, the orthodontic radiographs transmit higher dose than most of the large FOV CBCT, but it can be reduced if used rectangular collimation, showing lower effective dose than large FOV CBCT. Despite the image quality, the CBCT does not replace the FMX. In addition to the radiation dose, image quality and diagnostic needs should be strongly taken into account

Mutagenicity and cytotoxicity in patients submitted to ionizing radiation A comparison between cone beam computed tomography and radiographs for orthodontic treatment

Objectives: To evaluate and compare mutagenicity (micronucleus) and cytotoxicity (karyorrhexis, pyknosis, and karyolysis) in exfoliated buccal mucosa cells of children following cone beam computed tomography (CBCT) or conventional radiograph exposure necessary for orthodontic planning.Materials and Methods: A total of 49 healthy children were submitted to CBCT or a conventional orthodontic radiographic protocol; they were divided into two groups based on exam: CBCT (n = 24) and Radiographic Set (n = 25) groups. the micronucleus test in the exfoliated buccal mucosa cells was applied.Results: There was not a statistically significant difference (P > .05) found between the number of micronucleated buccal mucosa cells (MNC) before and after exposure to radiation in either group, showing that neither group experienced a mutagenic effect. However, radiation did cause other nuclear alterations closely related to cytotoxicity, including karyorrhexis, pyknosis, and karyolysis, in both groups (P < .05). the CBCT group presented a greater increase in cell death than was noted in the Radiographic Set group (P < .044).Conclusion: According to the micronucleus test, mutagenicity was not induced by the CBCT or the conventional radiographs, but cytotoxicity was verified after these exams, especially after CBCT. That might have happened once the CBCT group received a greater radiation dose than the Radiographic Set group as a result of the protocols used in orthodontic planning for this study. (Angle Orthod. 2013;83:104-109.)Univ Fed Rio de Janeiro, Dept Orthodont, BR-21941617 Rio de Janeiro, RJ, BrazilUniversidade Federal de São Paulo, Dept Pathol, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biosci, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Pathol, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biosci, São Paulo, BrazilWeb of Scienc

Evaluation of the shear bond strength of the Orthobond composite under different conditions

Objective: Evaluate the shear bond strength of metal brackets bonded with Orthobond composite (Dental Morelli Ltda, Sorocaba, Brazil) under different enamel surface conditions. Methods: Ninety bovine mandibular permanent incisors were divided into six groups (n = 15). In Group 1 (control) and Group 2 the bonding procedures were performed by using Transbond XT (3M Unitek, Monrovia, USA) and Orthobond (Dental Morelli Ltda, Sorocaba, Brazil) composites,respectively, according to the manufacturer’s recommendations. In the other groups brackets were bonded with Orthobond composite (Dental Morelli Ltda, Sorocaba, Brazil) as follows: Group 3 – dental surface conditioned with Transbond Plus Self-Etching Primer (3M Unitek, Monrovia, USA); Group 4 – bonding procedure without application of Orthoprimer (Dental Morelli Ltda, Sorocaba, Brazil); Group 5 - Eagle Bond applied on saliva/blood-contaminated dental surface; and Group 6 – use of homogenized Orthobond (Dental Morelli Ltda, Sorocaba, Brazil). After bonding the brackets, all the samples were submitted to shear bond strength tests by means of an Emic Universal Testing Machine at a crosshead speed of 0.5 mm/min. The results obtained in mega Pascal (MPa) were submitted to the analysis of variance (ANOVA) and then to the Tukey test. Results: The results in mega Pascal showed statistically significant differences between Groups 1 and 2 (p= 0.041), 1 and 5 (p=0.000) and between 4 and 5 (p=0.016). The ARI (Adhesive Remnant Index) scores showed evidence of a higher number of fractures at the bracket/composite interface. Conclusion: In all tested situations the Orthobond (Dental Morelli Ltda, Sorocaba, Brazil) was shown to be apt for bracket bonding

The evolution of cephalometric diagnosis in Orthodontics

INTRODUCTION: Although the development of CT have represented a landmark in diagnostic imaging, its use in Dentistry turned out very discretely over the years. With the appearance of programs for analysis of three-dimensional images, specific for Orthodontics and Orthognathic surgery, a new reality is being built. OBJECTIVE: The authors of this study aim to inform the orthodontic society of fundamentals about digital cephalometric radiographic image and computed tomography, discussing about: Field of view (FOV), radiation doses, demands for the use in Orthodontics and radiographic simulations

Evaluation of the reliability of measurements in cephalograms generated from cone beam computed tomography

OBJECTIVE: The purpose was to compare angular and linear measurements generated in digital cephalometric radiographs and cephalograms synthesized from three-dimensional images. METHODS: Twenty-six individuals (12 men and 14 women) with mean age of 26.3 years were selected. Digital cephalometric radiographs and CBCTs were taken on the same day. The images were imported and analyzed on Dolphin Imaging V.10.5 software, which synthesized cephalograms in perspective projection and magnification of 9.7%. A single observer marked the points and repeated the procedure with an interval of time of ten days to evaluate intraexaminer error. In the statistical analysis paired Student's t test was used to establish the correlation between the measurements. RESULTS: The angular measurements GoGn.SN and IMPA, which involved the Gonial point (Go) and the linear measurements that involved the lips presented significant difference (p < 0.05). The other measurements presented good correlation. CONCLUSION: The measurements in the synthesized cephalograms proved to be reliable

Effect of bleaching with hydrogen peroxide into different concentrations on shear strength of brackets bonded with a resin-modified glass ionomer

The evolution in glass ionomer cements has contributed to the reduction in dental caries in orthodontic patients because of the biological and chemical characteristics of this material; however no studies in the literature have evaluated the effect of bleaching treatment on the bond strength values of resin-modified glass ionomer cements (RMGICs). This study assessed the effect of a 6, 7.5 and 35% hydrogen peroxide bleaching gel on shear bond strength and bond failure site of brackets bonded with a resin-modified glass ionomer (Fuji Ortho LC, GC Europe, Leuven, Belgium). One hundred-fifty bovine mandibular permanent incisors were randomly divided into 10 groups; each group contained 15 teeth. Bleaching treatment was performed immediately at 2 different times before the bonding procedure. One hundred-fifty stainless steel brackets were bonded with the resin-modified glass ionomer. Following, all samples were stored in distilled water for 24 hours and then tested in shear mode on a Instron machine. ANOVA and Tukey&apos;s test showed statistical differences between the groups whose teeth were treated with 7.5% hydrogen peroxide and the control group. However, no statistical differences were found for the other groups (P > 0.05). With respect to adhesive remnant index (ARI), the majority of fractures occurred at the bracket/composite interface. Despite the decreased shear bond strength, the bonding of teeth whitened with different concentrations of hydrogen peroxide was found to be strong enough to resist mechanical and masticatory forces

Bonding brackets to porcelain: in vitro study

The aim of this research was to verify, in vitro, the effect of various porcelain surface treatments on the shear strength of orthodontic brackets bonded to porcelain and the mode of fracture after debonding. Eighty-eight samples of metallic supported feldspathic porcelain were randomly divided into four groups according to their surface preparation as follows: the porcelain was maintained intact (GI), roughened with a diamond bur (GII), etched with 10% hydrofluoric acid (GIII), or sandblasted with aluminum oxide (GIV). The specimens were treated with silane (Scothprime) and brackets were bonded with Concise. Each sample was subjected to a shear load at a crosshead speed of 1 mm/min and a recording was made at the point of failure. Bond strengths, adequate to withstand the application of orthodontic forces, were achieved in all groups. The Kruskal-Wallis statistical test showed no significant differences in bond strength between the groups (p>0.05). However, many more porcelain fractures occurred on deglazed porcelain. This study indicates that with the appropriate material selection, the silane/composite procedure alone may be adequate for bonding

Bonding brackets on white spot lesions pretreated by means of two methods

Abstract Objective: The aim of this study was to evaluate the shear bond strength (SBS) of brackets bonded to demineralized enamel pretreated with low viscosity Icon Infiltrant resin (DMG) and glass ionomer cement (Clinpro XT Varnish, 3M Unitek) with and without aging. Methods: A total of 75 bovine enamel specimens were allocated into five groups (n = 15). Group 1 was the control group in which the enamel surface was not demineralized. In the other four groups, the surfaces were submitted to cariogenic challenge and white spot lesions were treated. Groups 2 and 3 were treated with Icon Infiltrant resin; Groups 4 and 5, with Clinpro XT Varnish. After treatment, Groups 3 and 5 were artificially aged. Brackets were bonded with Transbond XT adhesive system and SBS was evaluated by means of a universal testing machine. Statistical analysis was performed by one-way analysis of variance followed by Tukey post-hoc test. Results: All groups tested presented shear bond strengths similar to or higher than the control group. Specimens of Group 4 had significantly higher shear bond strength values (p < 0.05) than the others. Conclusion: Pretreatment of white spot lesions, with or without aging, did not decrease the SBS of brackets

Maxillary dentoalveolar assessment following retraction of maxillary incisors: a preliminary study

ABSTRACT Objective: The aim of this preliminary study was to assess changes in tooth length and alveolar thickness following retraction of maxillary incisors. Methods: A total of 11 patients presenting severe maxillary dentoalveolar protrusion revealed by initial (T1) cone-beam computed tomography (CBCT), and whose treatment plan included extraction of maxillary first premolars and retraction of maxillary incisors, were selected and submitted to CBCT examination one month after the end of incisors retraction (T2). The premaxilla was assessed through seven axial slices by means of Dolphin ImagingTM software. In each of these slices, five measurements of the distance from the buccal cortical bone to the palatal cortical bone were performed. Tooth length of maxillary incisors (n = 44) was also measured in sagittal slices. Measurements were repeated after a two-week interval, and intraclass correlation coefficient (ICC) was used to test examiner calibration. Wilcoxon test was used to detect differences in measurements performed at the two time intervals. Results: The ICC was satisfactory for tooth length (0.890) and for premaxilla alveolar thickness measurements (0.980). Analysis of data showed no statistically significant differences (p > 0.05) in tooth length or alveolar thickness between the two-time intervals assessed. Conclusion: The force used in retraction of maxillary incisors in this research did not promote significant changes in tooth length of maxillary incisors or in premaxilla alveolar thickness