Marcelo Reis Fraga

Computed tomography evaluation of the temporomandibular joint in Class II Division 1 and Class III malocclusion patients: Condylar symmetry and condyle-fossa relationship

INTRODUCTION The purpose of this study was to investigate the condyle-fossa relationship, the concentric position of the condyles, and the dimensional and positional symmetries between the right and left condyles in Class II Division 1 and Class III malocclusion samples. METHODS Thirty subjects from 12 to 38 years of age with Class II Division 1 malocclusion and 16 subjects from 13 to 41 years of age with Class III malocclusion had computed tomography of the temporomandibular joints. The images obtained from the axial slices were evaluated for possible asymmetries in size and position between the condylar processes associated with these malocclusions. The images obtained from the sagittal slices were used to assess the depth of the mandibular fossa, the condyle-fossa relationship, and the concentric position of the condyles associated with these malocclusions. Paired Student t tests were applied, and Pearson product moment correlations were determined after measurements on both sides were obtained. RESULTS In the Class II Division 1 sample, the distance of condylar process/midsagittal plane (P = 0.019) and posterior joint space (P = 0.049) showed statistically significant differences between the right and left sides. In the Class III sample, there was no statistically significant difference between sides. Statistically significant (P <0.05) anterior positioning of the condyles was observed (nonconcentric positioning) in both the Class II Division 1 group and the Class III group. CONCLUSIONS In the Class II Division 1 malocclusion sample, the distance of condylar process/midsagittal plane and posterior articular space had statistically significant differences between the right and left sides. In the Class III sample, there was no statistically significant difference between sides. Evaluation of the concentric position of the condyles in their mandibular fossae showed nonconcentric positioning for the right and left sides in both the Class II and Class III malocclusion groups.

Computed tomography evaluation of the temporomandibular joint in Class I malocclusion patients: Condylar symmetry and condyle-fossa relationship

INTRODUCTION The purpose of this study was to investigate the condyle-fossa relationship, the concentric position of the condyles, and the dimensional and positional symmetries between the right and left condyles in subjects with Class I malocclusion. METHODS Thirty subjects from 13 to 30 years of age with Class I malocclusion had computed tomography imaging of the temporomandibular joints. The images obtained from axial slices were evaluated for possible asymmetries in size and position between the condylar processes associated with this malocclusion. The images obtained from sagittal slices were used to assess the depth of the mandibular fossa, the condyle-fossa relationship, and the concentric position of the condyles of this malocclusion. Paired Student t tests were applied, and Pearson product moment correlations were determined after measurements on both sides were obtained. RESULTS We found no statistically significant asymmetries between the condylar processes in this sample. No statistically significant asymmetries were found in the mandibular fossa depth, the anterior joint space, and the superior joint space. The posterior joint space showed statistically significant asymmetry (P <0.05) between the right and left sides. Statistically significant (P <0.05) anterior positioning of the condyles was observed (nonconcentric positioning). CONCLUSIONS Only the posterior articular space had a statistically significant difference between the right and left sides. There was a higher mean for posterior articular space on the right temporomandibular joint. Evaluation of the concentric position of the condyles in their mandibular fossae showed nonconcentric positioning for the 2 sides.

Cervical vertebral maturation as a biologic indicator of skeletal maturity

OBJECTIVE To identify and review the literature regarding the reliability of cervical vertebrae maturation (CVM) staging to predict the pubertal spurt. MATERIALS AND METHODS The selection criteria included cross-sectional and longitudinal descriptive studies in humans that evaluated qualitatively or quantitatively the accuracy and reproducibility of the CVM method on lateral cephalometric radiographs, as well as the correlation with a standard method established by hand-wrist radiographs. RESULTS The searches retrieved 343 unique citations. Twenty-three studies met the inclusion criteria. Six articles had moderate to high scores, while 17 of 23 had low scores. Analysis also showed a moderate to high statistically significant correlation between CVM and hand-wrist maturation methods. There was a moderate to high reproducibility of the CVM method, and only one specific study investigated the accuracy of the CVM index in detecting peak pubertal growth. CONCLUSIONS This systematic review has shown that the studies on CVM method for radiographic assessment of skeletal maturation stages suffer from serious methodological failures. Better-designed studies with adequate accuracy, reproducibility, and correlation analysis, including studies with appropriate sensitivity-specificity analysis, should be performed.

Correlation between miniscrew stability and bone mineral density in orthodontic patients

INTRODUCTION The aims of this study were to correlate the clinical and radiographic stability of titanium miniscrews when used as orthodontic anchorage for maxillary canine retraction and to assess bone quality. METHODS Thirty titanium miniscrews were placed in 15 consecutive patients (8 male, 7 female; age range, 12 years 5 months-32 years 11 months) as orthodontic anchorage. Orthodontic loads were applied immediately after miniscrew placement (T1) with a nickel-titanium closing coil spring. The initial estimated load was 200 g. The bone quality in each region of interest was determined by multi-slice computed tomography. RESULTS Bone mineral density (BMD) values ranged from 167 HU to 660.80 HU (mean, 420.63 HU). The specific regions had a mean close to the maximum value of a previously established scale for the posterior region of the maxilla (0-500 HU). The paired t test showed a statistically significant difference (P = 0.450) when the means of the differences between the right and left sides were compared. Twelve of the 15 subjects had significantly greater maxillary BMD on the right side. Linear regression also showed a low correlation between the 2 sides (P = 0.097). Clinically, the success index was 100%. Although 2 miniscrews were removed from 1 patient because of severe gingival inflammation with purulent secretion, none of the 28 remaining miniscrews showed any mobility after 90 days (T2). Comparisons of the means at T1 and T2 showed no statistically significant differences in these distances: between nasion and the miniscrew head, between orbitale and the miniscrew head, and between nasion and orbitale, assessed through cephalometric tracings made on lateral oblique radiographs (45 degrees ), pointing to the stability of the 28 miniscrews during the 90-day observation period. BMD values of all subjects were within the normal range of an established scale, and even close to maximum values. CONCLUSIONS The regions between the maxillary second premolars and first molars, and mesial to the maxillary second premolars, are safe as far as bone quality is concerned for miniscrew placement during the first 90 days of canine distalization. A good surgical technique and appropriate planning for miniscrew placement, inflammation control, and adequate oral hygiene are fundamental to the success of this new anchorage system during maxillary canine distalization.

Bone mineral density in cone beam computed tomography: Only a few shades of gray

Cone beam computed tomography (CBCT) has often been used to determine the quality of craniofacial bone structures through the determination of mineral density, which is based on gray scales of the images obtained. However, there is no consensus regarding the accuracy of the determination of the gray scales in these exams. This study aims to provide a literature review concerning the reliability of CBCT to determine bone mineral density. The gray values obtained with CBCT show a linear relationship with the attenuation coefficients of the materials, Hounsfield Units values obtained with medical computed tomography, and density values from dual energy X-ray absorciometry. However, errors are expected when CBCT images are used to define the quality of the scanned structures because these images show inconsistencies and arbitrariness in the gray values, particularly when related to abrupt change in the density of the object, X-ray beam hardening effect, scattered radiation, projection data discontinuity-related effect, differences between CBCT devices, changes in the volume of the field of view (FOV), and changes in the relationships of size and position between the FOV and the object evaluated. A few methods of mathematical correction of the gray scales in CBCT have been proposed; however, they do not generate consistent values that are independent of the devices and their configurations or of the scanned objects. Thus, CBCT should not be considered the examination of choice for the determination of bone and soft tissue mineral density at the current stage, particularly when values obtained are to be compared to predetermined standard values. Comparisons between symmetrically positioned structures inside the FOV and in relation to the exomass of the object, as it occurs with the right and left sides of the skull, seem to be viable because the effects on the gray scale in the regions of interest are the same.

The null hypothesis

model to a random-effect model would generate no change in the conclusions. Second, owing to the commonly found considerable heterogeneity across studies and a chief aim to merely provide pooled prevalence, many MCPs reported subgroup differences only in a descriptive manner rather than ambitiously giving the statistical significance of the differences. According to Higgins and Green, nonoverlap (and even overlap to a small degree) of the confidence intervals of the summary estimates is an indication of statistical significance. To avoid exaggeration, we used this relatively conservative method to estimate the rough degree of differences while describing them. As for publication bias, previous MCPs either made no mention or provided only an overall value of relevant statistics for all included studies (same as what we did). Actually, the chief concern for publication bias was that studies with negative results are less likely to be published. However, results of epidemiologic surveys concerning prevalence could not be considered either positive or negative. Furthermore, a previous study has shown that study size was not consistently associated with the probability of publication. Thus, to MCPs, the importance of publication bias and the traditional methods to estimate it might not be absolutely applicable. Conversely, information bias, selection bias, and performance bias have been highlighted for MCPs, all of which we endeavoured to avoid and evaluate in our analysis. For the last 3 or 4 years, MCPs have been rapidly gaining the interest of researchers. The elimination of inconformity and the improvement of quality of future MCPs might be one task that the Cochrane Collaboration could undertake before its 25th anniversary! Fang Hua Hong He Wassim Bouzid Wuhan, China

Orthodontic distalization with rigid plate fixation for anchorage after bone grafting and maxillary sinus lifting

A 68-year-old woman was treated with an autogenous particulated bone graft from the anterior part of the mandible to elevate the right maxillary sinus floor, which was next to the alveolar ridge of an edentulous area, to facilitate dental implant placement. A rigid plate for anchorage was placed into the zygomatic bone. The maxillary right canine and the premolars were moved distally 6 months after the implant was placed and osteointegration of the bone graft had occurred. The Class II relationship was corrected. After tooth movement, the patient underwent multislice computed tomography to determine the mineral density of the bone graft and compare it with the opposite side of the maxilla. The mineral density showed values above normal for the posterior segment of the maxilla. Although the patient was taking bisphosphonate for treatment of osteoporosis, no related complications were noted during treatment.

Apical root resorption: the dark side of the root.

INTRODUCTION The diagnosis of apical root resorption is usually based on routine radiographs. However, these methods are limited because the images reflect the superimposition of the whole root structure and can lead to underestimation of the extent of apical root resorption. In this study, we aimed to determine the lengths of the labial and lingual surfaces of incisors with apical root resorption and compare them with the longest radicular length obtained on sagittal images of cone-beam computed tomography, and to create a qualitative visual scale of the different patterns of apical root resorption. METHODS Eighty-two incisors with apical root resorption from 25 patients had their labial and lingual root surfaces and the longest radicular lengths determined in the sagittal plane and compared. Five orthodontists, at 2 times, classified the images of each incisor according to a visual scale developed by the authors. RESULTS There was no significant difference between the labial and lingual surfaces; however, the longest radicular length was significantly greater than the shortest surface length. The visual scale showed intraobserver agreement of 0.615 and interobserver agreements of 0.74 and 0.52 at both times, respectively. CONCLUSIONS The difference between the longest and shortest root lengths suggests that radiographic superimposition underestimates the extent of the resorption lesion. The proposed visual scale showed a frequency of agreement above 65% and a coefficient of reproducibility varying from moderate to substantial.

In-vitro study of the cellular viability and nitric oxide production by J774 macrophages with ceramic, polycarbonate, and polyoxymethylene brackets

INTRODUCTION Studies show that ceramic brackets are chemically inert in the oral cavity, whereas polycarbonate and polyoxymethylene brackets can degrade, releasing bisphenol-A and formaldehyde, respectively. In addition to the traditional cytotoxicity tests, the study of nitric oxide cellular production stimulated by a specific material has been shown to be a reliable tool for evaluating its cytotoxic potential. METHODS We aimed to assess cellular viability by MTT (Sigma, St. Louis, Mo): 3,(4,5-dimethylthiazol-2-yl)-2,5diphenyl tetrazolium bromide assay in a murine macrophage cell line J774 with esthetic brackets and quantify nitric oxide production by these macrophages. Cell cultures were evaluated at 3 times: 24, 48, and 72 hours. RESULTS Cellular viability in all groups was higher at 72 hours compared with 24 hours. This increase was significant in the control and ceramic brackets groups. Final means in the bracket groups showed no significant differences compared with the control group. Nitric oxide production was significantly greater in all groups at final time. There was no significant difference between the final means of the bracket groups and the control group, although polyoxymethylene brackets showed significantly greater means at 24 and 48 hours. CONCLUSIONS Final means in the bracket groups showed no significant differences compared with the control group.

In-vitro study of cellular viability and nitric oxide production by J774 macrophages stimulated by interferon gamma with ceramic, polycarbonate, and polyoxymethylene brackets

INTRODUCTION Ceramic brackets are chemically inert in the oral cavity, whereas polycarbonate and polyoxymethylene brackets can degrade and release bisphenol-A and formaldehyde, respectively. More reliable tests are needed to assess the potential toxicity of these materials. In addition to traditional cytotoxicity tests, the study of nitric oxide (NO) cellular production stimulated by a specific material has been shown to be a reliable tool for evaluating cytotoxic potential. The purpose of this study was to assess, with esthetic brackets, cellular viability by 3,(4,5-dimethylthiazol-2-yl)-2,5diphenyltetrazolium bromide assay (Sigma, St. Louis, Mo) in the macrophage cell line J774 stimulated with interferon gamma. Interferon gamma is a key cytokine in the activation of macrophages, plays an important role in immunologic processes, and also quantifies NO production by these macrophages. METHODS Well plates were seeded with 2 x 104 J774 cells per well, in a volume of 100 microL, resuspended in Roswell Park Memorial Institute Supplemented Medium 1640. The macrophage cell line J774 was stimulated with interferon gamma. Ceramic, polycarbonate, and polyoxymethylene brackets were added and kept in the culture for 24, 48, or 72 hours in 5% carbon dioxide at 37 degrees C; the control samples did not include brackets. At the end of each incubation period, the supernatant was collected for posterior NO quantification, and the cells were evaluated for cytotoxicity. RESULTS Cellular viability in all groups was higher at 72 hours than at 24 hours. The final means in the bracket groups did not show significant differences compared with the control group. NO production was significantly greater in all groups at the final time than at the initial time. However, the brackets with the interferon gamma stimulation did not result in greater NO production than did the cells in the control group.