Lucia Helena Soares Cevidanes

Observer reliability of three-dimensional cephalometric landmark identification on cone-beam computerized tomography

OBJECTIVEnTo evaluate reliability in 3-dimensional (3D) landmark identification using cone-beam computerized tomography (CBCT).nnnSTUDY DESIGNnTwelve presurgery CBCTs were randomly selected from 159 orthognathic surgery patients. Three observers independently repeated 3 times the identification of 30 landmarks in the sagittal, coronal, and axial slices. A mixed-effects analysis of variance model estimated the intraclass correlations (ICC) and assessed systematic bias.nnnRESULTSnThe ICC was >0.9 for 86% of intraobserver assessments and 66% of interobserver assessments. Only 1% of intraobserver and 3% of interobserver coefficients were <0.45. The systematic difference among observers was greater in X and Z than in Y dimensions, but the maximum mean difference was quite small.nnnCONCLUSIONnOverall, the intra- and interobserver reliability was excellent. Three-dimensional landmark identification using CBCT can offer consistent and reproducible data if a protocol for operator training and calibration is followed. This is particularly important for landmarks not easily specified in all 3 planes of space.

In Vivo Comparison of Conventional and Cone Beam CT Synthesized Cephalograms

OBJECTIVEnTo compare measurements from synthesized cone-beam computed tomography (CBCT) lateral cephalograms using orthogonal and perspective projections with those from conventional cephalometric radiographs.nnnMATERIALS AND METHODSnThirty-one patients were imaged using CBCT and conventional cephalometry. CBCT volume data were imported in Dolphin 3D. Orthogonal and perspective lateral cephalometric radiographs were created from three-dimensional (3D) virtual models. Twelve linear and five angular measurements were made on synthesized and conventional cephalograms in a randomized fashion. Conventional image measurements were corrected for known magnification. Linear and angular measurements were compared between image modalities using repeated measures analysis of variance. Statistical significance was defined as an alpha level of .01.nnnRESULTSnWith the exception of the Frankfort-mandibular plane angle (P < .0001), angular measurements were not statistically different for any modality (P > .01). Linear measurements, whether based on soft or hard tissue landmarks, were not statistically different (P > .01).nnnCONCLUSIONSnMeasurements from in vivo CBCT synthesized cephalograms are similar to those based on conventional radiographic images. Thus, additional conventional imaging may generally be avoided when CBCT scans are acquired for orthodontic diagnosis.

Precision of cephalometric landmark identification: Cone-beam computed tomography vs conventional cephalometric views

INTRODUCTIONnIn this study, we compared the precision of landmark identification using displays of multi-planar cone-beam computed tomographic (CBCT) volumes and conventional lateral cephalograms (Ceph).nnnMETHODSnTwenty presurgical orthodontic patients were radiographed with conventional Ceph and CBCT techniques. Five observers plotted 24 landmarks using computer displays of multi-planer reconstruction (MPR) CBCT and Ceph views during separate sessions. Absolute differences between each observers plot and the mean of all observers were averaged as 1 measure of variability (ODM). The absolute difference of each observer from any other observer was averaged as a second measure of variability (DEO). ANOVA and paired t tests were used to analyze variability differences.nnnRESULTSnRadiographic modality and landmark were significant at P <0.0001 for DEO and ODM calculations. DEO calculations of observer variability were consistently greater than ODM. The overall correlation of 1920 paired ODM and DEO measurements was excellent at 0.972. All bilateral landmarks had increased precision when identified in the MPR views. Mediolateral variability was statistically greater than anteroposterior or caudal-cranial variability for 5 landmarks in the MPR views.nnnCONCLUSIONSnThe MPR displays of CBCT volume images provide generally more precise identification of traditional cephalometric landmarks. More precise location of condylion, gonion, and orbitale overcomes the problem of superimposition of these bilateral landmarks seen in Ceph. Greater variability of certain landmarks in the mediolateral direction is probably related to inadequate definition of the landmarks in the third dimension.

Orthopedic traction of the maxilla with miniplates: a new perspective for treatment of midface deficiency.

Class III malocclusion is a consequence of maxillary deficiency and/or mandibular prognathism, often resulting in an anterior crossbite and a concave profile.1 Young patients with maxillary hypoplasia are usually treated with a facemask: heavy anterior traction is applied on the maxilla to stimulate its growth and to restrain or redirect mandibular growth. Forward and downward movement of the maxilla as well as favorable changes in the amount and direction of mandibular growth has been reported.2–5 However, these forces generally result in a posterior rotation of the mandible and an increased vertical dimension of the face.2,4,6 Moreover, dental compensations (proclination of the upper incisors and uprighting of the lower incisors) are observed as a consequence of the application of forces on the teeth,4,7 and facemask wear is usually limited to 14 hours per day at best. n nTitanium miniplates used for anchorage now offer the possibility to apply pure bone-borne orthopedic forces between the maxilla and the mandible for 24 hours per day, avoiding any dentoalveolar compensations.

Dentofacial effects of bone-anchored maxillary protraction: A controlled study of consecutively treated Class III patients

INTRODUCTIONnIn this cephalometric investigation, we analyzed the treatment effects of bone-anchored maxillary protraction (BAMP) with miniplates in the maxilla and mandible connected by Class III elastics in patients with Class III malocclusion.nnnMETHODSnThe treated sample consisted of 21 Class III patients consecutively treated with the BAMP protocol before the pubertal growth spurt (mean age, 11.10 ± 1.8 years) and reevaluated after BAMP therapy, about 1 year later. The treated group was compared with a matched control group of 18 untreated Class III subjects. Significant differences between the treated and control groups were assessed with independent-sample t tests (P <0.05).nnnRESULTSnSagittal measurements of the maxilla showed highly significant improvements during active treatment (about 4 mm more than the untreated controls), with significant protraction effects at orbitale and pterygomaxillare. Significant improvements of overjet and molar relationship were recorded, as well as in the mandibular skeletal measures at Point B and pogonion. Vertical skeletal changes and modifications in incisor inclination were negligible, except for a significant proclination of the mandibular incisors in the treated group. Significant soft-tissue changes reflected the underlying skeletal modifications.nnnCONCLUSIONSnCompared with growth of the untreated Class III subjects, the BAMP protocol induced an average increment on skeletal and soft-tissue advancement of maxillary structures of about 4 mm, and favorable mandibular changes exceeded 2 mm.

Comparison of two protocols for maxillary protraction: Bone anchors versus face mask with rapid maxillary expansion

OBJECTIVEnTo test the hypothesis that there is no difference in the active treatment effects for maxillary advancement induced by bone-anchored maxillary protraction (BAMP) and the active treatment effects for face mask in association with rapid maxillary expansion (RME/FM).nnnMATERIALS AND METHODSnThis is a study on consecutively treated patients. The changes in dentoskeletal cephalometric variables from start of treatment (T1) to end of active treatment (T2) with an average T1-T2 interval of about 1 year were contrasted in a BAMP sample of 21 subjects with a RME/FM sample of 34 patients. All subjects were prepubertal at T1. Statistical comparison was performed with t-tests for independent samples.nnnRESULTSnThe BAMP protocol produced significantly larger maxillary advancement than the RME/FM therapy (with a difference of 2 mm to 3 mm). Mandibular sagittal changes were similar, while vertical changes were better controlled with BAMP. The sagittal intermaxillary relationships improved 2.5 mm more in the BAMP patients. Additional favorable outcomes of BAMP treatment were the lack of clockwise rotation of the mandible as well as a lack of retroclination of the lower incisors.nnnCONCLUSIONSnThe hypothesis is rejected. The BAMP protocol produced significantly larger maxillary advancement than the RME/FM therapy.

Quantification of condylar resorption in temporomandibular joint osteoarthritis

OBJECTIVEnThis study was performed to determine the condylar morphologic variation of osteoarthritic (OA) and asymptomatic temporomandibular joints (TMJs) and to determine its correlation with pain intensity and duration.nnnSTUDY DESIGNnThree-dimensional surface models of mandibular condyles were constructed from cone-beam computerized tomography images of 29 female patients with TMJ OA (Research Diagnostic Criteria for Temporomandibular Disorders group III) and 36 female asymptomatic subjects. Shape correspondence was used to localize and quantify the condylar morphology. Statistical analysis was performed with multivariate analysis of covariance analysis, using Hotelling T(2) metric based on covariance matrices, and Pearson correlation.nnnRESULTSnThe OA condylar morphology was statistically significantly different from the asymptomatic condyles (P < .05). Three-dimensional morphologic variation of the OA condyles was significantly correlated with pain intensity and duration.nnnCONCLUSIONnThree-dimensional quantification of condylar morphology revealed profound differences between OA and asymptomatic condyles, and the extent of the resorptive changes paralleled pain severity and duration.

Comparison of actual surgical outcomes and 3-dimensional surgical simulations

PURPOSEnThe advent of imaging software programs has proved to be useful for diagnosis, treatment planning, and outcome measurement, but precision of 3-dimensional (3D) surgical simulation still needs to be tested. This study was conducted to determine whether the virtual surgery performed on 3D models constructed from cone-beam computed tomography (CBCT) can correctly simulate the actual surgical outcome and to validate the ability of this emerging technology to recreate the orthognathic surgery hard tissue movements in 3 translational and 3 rotational planes of space.nnnMATERIALS AND METHODSnConstruction of pre- and postsurgery 3D models from CBCTs of 14 patients who had combined maxillary advancement and mandibular setback surgery and 6 patients who had 1-piece maxillary advancement surgery was performed. The postsurgery and virtually simulated surgery 3D models were registered at the cranial base to quantify differences between simulated and actual surgery models. Hotelling t tests were used to assess the differences between simulated and actual surgical outcomes.nnnRESULTSnFor all anatomic regions of interest, there was no statistically significant difference between the simulated and the actual surgical models. The right lateral ramus was the only region that showed a statistically significant, but small difference when comparing 2- and 1-jaw surgeries.nnnCONCLUSIONSnVirtual surgical methods were reliably reproduced. Oral surgery residents could benefit from virtual surgical training. Computer simulation has the potential to increase predictability in the operating room.

Three-dimensional analysis of maxillary protraction with intermaxillary elastics to miniplates.

INTRODUCTIONnEarly Class III treatment with reverse-pull headgear generally results in maxillary skeletal protraction but is frequently also accompanied by unfavorable dentoalveolar effects. An alternative treatment with intermaxillary elastics from a temporary anchorage device might permit equivalent favorable skeletal changes without the unwanted dentoalveolar effects.nnnMETHODSnSix consecutive patients (3 boys, 3 girls; ages, 10-13 years 3 months) with Class III occlusion and maxillary deficiency were treated by using intermaxillary elastics to titanium miniplates. Cone-beam computed tomography scans taken before and after treatment were used to create 3-dimensional volumetric models that were superimposed on nongrowing structures in the anterior cranial base to determine anatomic changes during treatment.nnnRESULTSnThe effect of the intermaxillary elastic forces was throughout the nasomaxillary structures. All 6 patients showed improvements in the skeletal relationship, primarily through maxillary advancement with little effect on the dentoalveolar units or change in mandibular position.nnnCONCLUSIONSnThe use of intermaxillary forces applied to temporary anchorage devices appears to be a promising treatment method.

Three-dimensional assessment of maxillary changes associated with bone anchored maxillary protraction

INTRODUCTIONnBone-anchored maxillary protraction has been shown to be an effective treatment modality for the correction of Class III malocclusions. The purpose of this study was to evaluate 3-dimensional changes in the maxilla, the surrounding hard and soft tissues, and the circummaxillary sutures after bone-anchored maxillary protraction treatment.nnnMETHODSnTwenty-five consecutive skeletal Class III patients between the ages of 9 and 13 years (mean, 11.10 ± 1.1 years) were treated with Class III intermaxillary elastics and bilateral miniplates (2 in the infrazygomatic crests of the maxilla and 2 in the anterior mandible). Cone-beam computed tomographs were taken before initial loading and 1 year out. Three-dimensional models were generated from the tomographs, registered on the anterior cranial base, superimposed, and analyzed by using color maps.nnnRESULTSnThe maxilla showed a mean forward displacement of 3.7 mm, and the zygomas and the maxillary incisors came forward 3.7 and 4.3 mm, respectively.nnnCONCLUSIONSnThis treatment approach produced significant orthopedic changes in the maxilla and the zygomas in growing Class III patients.