Cephalometric Points Research Articles

An interim analysis of the maxillary canine in determining the maxillary occlusal plane

Aim: A pilot study on dentate subjects was done to evaluate the relationship of the incisal edge exposures of the maxillary central incisor (CI) and maxillary canine to the maxillary lip at rest, to the maxillary lip length, and the influential effects of incisal wear and anteroposterior skeletal relation. Materials and Methods: Thirty males and 67 females of Indian origin and age group 15-59 years were examined. A calibrated manual vernier caliper was used to record the incisal exposures of the maxillary left CI and canine to the maxillary lip at rest and the maxillary lip length. The tooth wear index by Smith and Knight (1984) was used to assess the extent and severity of the incisal attrition. Anteroposterior skeletal relation was assessed using soft tissue cephalometric points. A descriptive statistical analysis and Pearson's correlation analysis was done. Results: On descriptive analysis of the data recorded, 94% of the female subjects recorded a mean CI exposure of 3.25 mm to the maxillary lip at rest while 91% of the female subjects recorded a mean canine exposure of 0.29 mm. 93% of the male subjects recorded a mean CI exposure of 2.63 mm to the maxillary lip at rest. 80% of the male subjects recorded a mean canine exposure of −0.42 mm to the maxillary lip at rest. Canine displayed a narrow range of tooth visibility. In both genders, CI exposure to the mean lip length averaged 1-3 mm and the canine exposure to the mean lip length averaged −1-0 mm. CI and canine incisal edge exposures decreased with an increased incisal wear. CI exposure averaged 0-3 mm and canine exposures averaged −1-1 mm. Class II and Class I skeletal relation observed an increased CI exposure of 3 mm and 2.4 mm respectively compared to Class III (2.125 mm). Increased canine exposures were observed for Class III (0.3 mm) and Class II (0 mm) compared to Class I (−0.7 mm). Pearson's correlative analysis demonstrated a highly significant positive correlation of the canine with a P value of 0.01. Conclusion: Within the scope of this study, descriptive analysis demonstrated a linear favorable relationship of the canine to the CI. Correlative analysis also demonstrated a favorable relationship of canine to CI with borderline significance of anteroposterior relationship.

Virtual Surgical Planning for Orthognathic Surgery Using Digital Data Transfer and an Intraoral Fiducial Marker: The Charlotte Method

We describe an alternative workup protocol for virtual surgical planning of orthognathic surgery using an intraoral fiducial marker, clinical photography, and the digital transfer of occlusal data. Wealso discuss our initial experience using this protocol in a series of patients. A retrospective cohort study was performed of consecutive patients who had undergone combined maxillary and mandibular osteotomies for the correction of dentofacial deformities at 1 center. These patients underwent treatment planning using the modified virtual surgical planning protocol described in the present report. The primary outcome evaluated was the accuracy of the method, which was determined through superimposition of the surgical plan to the postoperative cone-beam computed tomography (CBCT) scan. The secondary outcomes included the accuracy of the natural head position readings and the adequacy of the CBCT scanned stone models for the fabrication of occlusal splints. The population included 25 patients. The root mean standard deviation (RMSD) from the preoperative plan to the postoperative scan at the maxillary cephalometric points was 1.2, 1.4, and 2.1mm in the axial, sagittal, and coronal planes, respectively. The RMSD of the superimposed plan to the postoperative scan at the 3 mandibular cephalometric points was 1.2, 0.8, and 0.7mm in the axial, sagittal, and coronal planes, respectively. The average variance from the axial, sagittal, and coronal planes for the natural head position was 0.05, 2.22, and 0.69 mm, respectively. All splints fabricated from the CBCT occlusal data fit the stone models and were used intraoperatively. In the subset of patients whose models were both digitally transferred and laser scanned, the superimposition of the laser scan data to the CBCT scanned data was found to have a maximum variation of 0.2mm at the occlusal level. The use of an intraoral fiducial marker changed the workflow for the data collection needed for virtual surgical planning of the correction of dentofacial deformities, while still obtaining accurate results. Because the device does not cause lip distortion, the possibility of virtually predicting a more expectant postoperative lip position exists without the need for additional scans. Furthermore, this work flow allows the transfer of data to be isolated to digital media.

Pharyngeal airway space cephalometric evaluation in transverse maxillary deficient patients after SARME

Aim: To evaluate prospectively the upper airway of 16 patients submitted to surgically assisted rapid maxillary expansion. Methods: Volumetric tomography acquisitions were done preoperatively (T1) and after six months postoperatively (T2), the slices were obtained from the hard palate to the third cervical vertebra (C3), the images were imported and reconstructed in the Dolphin software for 2D definition of the upper airway. A cephalometric radiograph was generated by the software, the cephalometric points were traced at T1 and T2 for all patients in a dark environment always by the same operator and the Arnett-Gunson FAB Surgery analysis was applied. Results: A statistically significant reduction in area (p=0.03) at the level of the nasopharynx was observed, while at the oropharynx and hypopharynx it showed no statistical difference between T1 and T2. Conclusions: The area in the nasopharynx level presented a statistically significant decrease, however, despite the area decrease at this point, the patients seem to do better, and thus, this area decrease may not be clinically significant.

Factors influencing superimposition error of 3D cephalometric landmarks by plane orientation method using 4 reference points: 4 point superimposition error regression model.

Superimposition has been used as a method to evaluate the changes of orthodontic or orthopedic treatment in the dental field. With the introduction of cone beam CT (CBCT), evaluating 3 dimensional changes after treatment became possible by superimposition. 4 point plane orientation is one of the simplest ways to achieve superimposition of 3 dimensional images. To find factors influencing superimposition error of cephalometric landmarks by 4 point plane orientation method and to evaluate the reproducibility of cephalometric landmarks for analyzing superimposition error, 20 patients were analyzed who had normal skeletal and occlusal relationship and took CBCT for diagnosis of temporomandibular disorder. The nasion, sella turcica, basion and midpoint between the left and the right most posterior point of the lesser wing of sphenoidal bone were used to define a three-dimensional (3D) anatomical reference co-ordinate system. Another 15 reference cephalometric points were also determined three times in the same image. Reorientation error of each landmark could be explained substantially (23%) by linear regression model, which consists of 3 factors describing position of each landmark towards reference axes and locating error. 4 point plane orientation system may produce an amount of reorientation error that may vary according to the perpendicular distance between the landmark and the x-axis; the reorientation error also increases as the locating error and shift of reference axes viewed from each landmark increases. Therefore, in order to reduce the reorientation error, accuracy of all landmarks including the reference points is important. Construction of the regression model using reference points of greater precision is required for the clinical application of this model.

Efficacy of Interpositional Arthroplasty with Temporalis Myofascia Flap in Treatment of TMJ Ankylosis

Aims and objective: The present study was done to evaluate the efficacy of interpositional arthroplasty with temporalis muscle and fascia (myofascia) flap in preventing the re-ankylosis, to evaluate the growth of mandible, and to assess Al-Kayat and Bramley’s incision for its versatility in allowing muscle transfer and excellent exposure of the joint. Materials and Methods: Fifteen patients with ankylosis were treated with interpositional arthroplasty with temporalis myofascia flap. Maximum Interincisal Opening (MIO) was measured at different periods, i.e. preoperative, intraoperative, immediate post operative, 1 month post-operative, 6 month post-operative, 1 year post-operative. Pain was measured using Visual analogue scales in closed mouth position (spontaneously) & on mouth opening. Six cephalometric points were taken for evaluating the mandibular growth. Results: A statistically significant difference of 30.73 mm (p<0.001) was obtained between pre-operative and post-operative interincisal opening after a period of one year follow up. The pain score at different periods of time revealed that the pain incidence significantly reduced to almost zero post-operatively (p<0.5 for closed mouth, p<0.01 for open mouth).

Canine retraction and anchorage loss: Self-ligating versus conventional brackets in a randomized split-mouth study

To evaluate the velocity of canine retraction, anchorage loss and changes on canine and first molar inclinations using self-ligating and conventional brackets. Twenty-five adults with Class I malocclusion and a treatment plan involving extractions of four first premolars were selected for this randomized split-mouth control trial. Patients had either conventional or self-ligating brackets bonded to maxillary canines randomly. Retraction was accomplished using 100-g nickel-titanium closed coil springs, which were reactivated every 4 weeks. Oblique radiographs were taken before and after canine retraction was completed, and the cephalograms were superimposed on stable structures of the maxilla. Cephalometric points were digitized twice by a blinded operator for error control, and the following landmarks were collected: canine cusp and apex horizontal changes, molar cusp and apex horizontal changes, and angulation changes in canines and molars. The blinded data, which were normally distributed, were analyzed through paired t-tests for group differences. No differences were found between the two groups for all variables tested. Both brackets showed the same velocity of canine retraction and loss of anteroposterior anchorage of the molars. No changes were found between brackets regarding the inclination of canines and first molars.

Assessment of Skeletal Stability After Counterclockwise Rotation of the Maxillomandibular Complex in Patients With Long-Face Pattern Subjected to Orthognathic Surgery

The aim of this study was to evaluate the long-term skeletal stability of counterclockwise maxillomandibular complex rotation in patients undergoing orthognathic surgery for long-face pattern. This retrospective study consisted of 10 patients who underwent the procedure between September 2002 and April 2008. To assess the skeletal stability, 30 preoperative (T1), recent postoperative (T2), and late postoperative (T3) cephalometric radiographs of the 10 patients were digitized and traced. To measure the stability in the occlusal plane and mandibular plane, the cephalometric points and planes were determined 3 times. In the long term, on average, the A-point moved 0.21 mm backward (AYT3-AYT2), the B-point moved 0.57 mm backward (BYT3-BYT2), and the posterior nasal spine moved 0.31 mm backward (PNSYT3-PNSYT2). On average, the anterior maxillary area (A-point) moved 0.14 mm downward (AXT3-AXT2), the mandible (B-point) moved 0.07 mm downward (BXT3-BXT2), and the posterior nasal spine moved approximately 0.18 mm upward (PNSXT3-PNSXT2). The occlusal plane increased by 0.75 degrees (OPT3-OPT2), and the mandibular plane increased by 0.45 degrees (MPT3-MPT2). It was observed that the counterclockwise rotation of the maxillomandibular complex produces stable results in patients with long-face pattern undergoing orthognathic surgery.

A Study of Facial Pattern in Patients with Fanconi Anemia

This study is aimed to evaluate craniofacial features in patients with Fanconi anemia (FA) through cephalometric analysis and to classify the facial growth pattern to observe possible facial discrepancies. This is a cross-sectional study which employed a quantitative approach to compare linear and angular measurements of cephalometric analysis in lateral teleradiographic images of a clinical type sample of patients with FA. A retrospective cephalometric study was performed using cephalometric analyses of Ricketts and Steiner; growth patterns according to Ricketts' vertical growth pattern (VERT index) were also analyzed. Fifty patients diagnosed with FA who were undergoing anti-aplasia treatment at the outpatient Hematology service at the Federal University of Paraná, Curitiba, Brazil were included in the study. The patients were evaluated in the School of Dentistry of the Pontifical Catholic University of Paraná (PUCPR), Curitiba, Brazil. Exclusion criteria included patients who had used or were using growth hormone medication, had undergone bone marrow transplant, or had been previously subjected to dental treatment. Cephalometric points were plotted in order to set up linear and angular cephalometric measurements. Angular and linear measurements from 17 factors proposed by Ricketts' cephalometric analysis were assessed. Dolicofacial appearance was observed in 52% of individuals; braquifacial in 28%, and mesofacial in 20%. Significant maxillary/mandibular discrepancy was observed. It was concluded that upon anteroposterior evaluation of facial bone structures, the FA sample presented smaller median measurements in most variables evaluated; it also presented mandibular micrognathism and mainly dolicofacial vertical growth pattern. These findings, together with other features such as skin pigmentation and microphthalmia, may lead to a possible recognition of a FA condition from a patient's facial features.

Attempted validation of a method to locate entry and exit foramens of the branches of the trigeminal nerve; benefits for an original cephalometric analysis technique

Trigeminal analysis focuses on the skeletal entrance and exit orifices of the sensitive fibers of the trigeminal nerve. The aim of this study was to validate the techniques used to locate these landmarks as described by the creator of trigeminal analysis of the face. This descriptive study was performed on a dry human skull. Two tin balls forming markers R1 and R2 were fixed at random on the skull in a median sagittal position. Two headfilms of the skull were made. The first showed tin balls fixed at the entrance and exit foramens of the sensitive fibers of the trigeminal nerve. The second showed the foramens without the tin balls. The position of the reference point corresponding to the entrance and exit points of the trigeminal fibers was entered on a tracing made from the headfilm (without the balls on the foramens) by 16operators using an ad hoc guide supplied by Crocquet. A comparison was made between the points as positioned by these operators and the true points as revealed by the X-rays of the balls on the first image (Gold Standard) by calculating the difference between their coordinates on an axis connecting R1 et R2 (X-axis) and the line perpendicular to it passing through R2 (Y-axis). Trigeminal cephalometric analysis was then performed on each of the tracings. The angles and linear values were compared. The validity of the positioning of the points and of the values provided by the analysis was demonstrated by the existence of a difference of less than 2units (mm or degrees). No difference in the means between the trigeminal points found by the operators and the Gold Standard points represented by the X-rays of the balls placed on the foramens exceeded 2mm in absolute value on the Y-axis. On the X-axis, the differences greater than 2mm in absolute value related to: the supra-orbital notch (ESO) and the foramen ovale (FO) (2.12 and 8.19mm, respectively). The angles (ESO-TGR-TO) and (TGR-ESO-TSO) were the only ones to display differences exceeding 2° in absolute value between the two images. The detection method advanced by Crocquet for the positioning of the eightpoints of reference used for analyzing the entrance and exit foramens of the trigeminal nerve is valid apart from the TO and ESO points. Consequently, the validity of the angle measurements involving these points is affected. Further research is required to confirm these findings. If necessary, new recommendations should be devised in order to improve the localization of the TO and ESO cephalometric points.

Effects of Internal Rigid Fixation on Mandibular Development in Growing Rabbits With Mandibular Fractures

The aim of this research was to determine whether rigid internal fixation interferes with mandibular growth and development in growing New Zealand white rabbits with induced mandibular fractures. Ten 3-month-old New Zealand white rabbits were included in the study. Surgical fractures were performed in the right mandibular bodies of the 10 rabbits. These fractures were reduced with internal rigid fixation by use of a 1.0-mm titanium system, taking the contralateral left mandibular bodies as the control group. We obtained radiographs preoperatively and at 1, 2, and 3 months postoperatively. Predetermined cephalometric points were used to measure and compare jaw growth. The protocol was approved by the Bioethics Committee of Universidad El Bosque, Bogotá, Colombia. There were no statistically significant differences between the experimental and control groups (P = .95). Mandibular growth in the studied rabbits was not affected by the use of internal rigid fixation. The use of internal rigid fixation for the treatment of induced mandibular fractures in growing rabbits did not alter the normal process of growth and development. The findings of this study should lead to investigations using larger samples and to long-term prospective follow-up studies of children who have undergone open reduction and internal rigid fixation.

Les erreurs de mesure en céphalométrie 2D

The objective of this study is to analyze the influence that two parameters, the source-subject distance and the type of receptor, have on the precision of localization of the 19 most frequently employed cephalometric landmark points and then to analyze the repercussions of localization errors on cephalometric measurements. The correct use of profile cephalograms (norma lateralis) for clinical purposes depends essentially on the precision of the identification and localization of the different landmark points that are required for the elaboration of the various cephalometric analyses. For this study we asked 53 orthodontists, selected at random, to identify 19 cephalometric points on standard profile or digitized films taken at distances of 1m 50 or of 4 m. The results we obtained show no statistically significant differences in relation to the source-subject distance or to the type of receptor. Each cephalometric landmark presented a characteristic dispersion cloud; the most reliable points were primarily located on the median sagittal plane. The cephalometric measurements that demonstrated the greatest variability were associated with positions of the incisor apices, which makes their value doubtful in the establishment of treatment plans and in ongoing evaluations of treatment progress. For similar reasons, the worth of the Frankfort plane can be questioned when it is compared to other, much more reliable cranial reference planes especially S-Na.

Direct 3D Cephalometric Analysis Performed on CBCT

Cone Beam Computed Tomography produces distortion-free and accurate images of the craniofacial anatomy, and can be considered as a useful instrument to perform a correct diagnosis and treatment using a cephalometric analysis. Now a days the 3D cephalometric analysis are made by adapting on 3D what was born on 2D, so it can be necessary to find a new technique that was born directly on 3D.Sixty-five Ricketts’ first skeletal classes were chosen in an archive of 700 CBCT acquisitions. 3 easily repeatable reference planes were found on each case and then 15 points were selected on the skull, for a total of 18 cephalometric points. Each point of these 65 patients creates a cloud of points that could represent the range of normality in the 3D space. The coordinates of each analyzed point presented a standard deviation between 0, 00 and 5, 64. This range of values may be considered representative for the first skeletal class.Authors agree that further studies are needed but the Direct 3D cephalometric analysis may be considered a new easy, precise and rapid way to reach a correct diagnosis and treatment with a cephalometric analysis born directly on 3D.

Evaluation of extraction and non-extraction treatment effects by two different superimposition methods

The aim of this study was to determine whether different evaluation methods may be the cause of the varied outcomes of research that have evaluated the effects of extraction and non-extraction therapy on jaw rotation. This retrospective study consisted of the pre- (T1) and post- (T2) treatment lateral cephalograms of 70 skeletal Class I subjects with an optimal vertical mandibular plane angle, who had undergone fixed orthodontic treatment. Thirty-five of the subjects (20 females and 15 males, mean age: 14.7 years) were treated with four first premolar extractions and 35 (22 females and 13 males, mean age: 15 years) without extractions. T1 and T2 radiographs were superimposed using Björk's structural method and Steiner's method of sella-nasion line registered at sella. A Wilcoxon test was used to evaluate the changes between T1 and T2 and the Mann-Whitney U-test to determine differences between the extraction and non-extraction and Björk and Steiner groups. No significant difference was found between the methods of Steiner and Björk according to the spatial changes of the cephalometric points in the extraction and non-extraction groups. The maxilla showed forward rotation in the extraction group and backward rotation in the non-extraction group with both superimposition methods, but the differences were not significant in either inter- or intraclass comparisons. The mandible showed forward rotation in the extraction group with both superimposition methods but, in the non-extraction group, forward rotation was recorded with Björk's method and backward rotation with Steiner's method. These findings were not significant in either inter- or intraclass evaluations. No significant difference was found between the groups or methods.

Permutation method for evaluating topographic craniofacial correlations

Correlations between cephalometric measurements are frequently assumed to represent biologic associations. However, a significant portion of such correlations might arise from purely geometric dependencies, when measurements share common landmarks. Analytic calculation of this topographic component is difficult. The purpose of this study was to propose a permutation method for evaluating the topographic component of cephalometric correlations. The method consisted of creating a virtual sample of cephalometric tracings (landmark configurations) from the original biologic sample under investigation. Each novel landmark configuration was constructed by assigning coordinates to the cephalometric points; the coordinates of each point were taken randomly from the original sample, each from a potentially different subject. Correlation analysis was performed separately on both samples and the results compared. Biologic meaning was ascribed only when there was a significant difference in correlation values between the samples. Confidence intervals for assessing statistical significance were calculated by using a randomization approach. The method was tested on a sample of 170 radiographs to evaluate the correlation between cranial base angle (NSBa) and angles SNA and SNB, as well as between ANB angle and the Wits appraisal. No biologic association was found between ANB and Wits, or between NSBa and SNA. The biologic correlation between NSBa and SNB was statistically significant but low (r(2) = 12%). Topographic associations between cephalometric measurements are ubiquitous and difficult to assess. The proposed method enables evaluation of their relative strength without the need for analytic solutions.

Facial features of patients with sickle cell anemia

To characterize the craniofacial features of patients with sickle cell anemia (SCA). Fifty patients with SCA in the north of Minas Gerais, Brazil, were evaluated using standardized photographs (front and profile) for a subjective facial analysis and digital radiographs for a computerized cephalometric analysis. To obtain linear and angular measurements, cephalometric points were marked on the digital images by a single examiner, using the program Radiocef 6.0, and facial analyses were performed by four different orthodontists. Of the population studied, 28 patients were female with a mean age of 27.7 years. Most of the patients (64%) had their faces classified as esthetically acceptable, although results showed a predominance of convex profiles (72%). The mean of the SNA angle was 84.56°, diagnosing proper positioning of the maxilla from the base of the skull. The prevalence of pattern II was 32%, and 31% showed maxillary protrusion; the effective length of the maxilla was reduced in 64%. Retrusion of the mandible was observed in 30%, and 76% had reduced mandibular length. Four measurements (mandibular length, maxillary length, anterior face height, and maxillomandibular difference) showed statistically significant differences between genders, where these measurements were higher for males than for females. Most patients did not show compensatory maxillary expansion, which was determined by the prevalence of decreased maxillary length (64%) and by the absence of maxillary protrusion in 69% of the SCA patients evaluated.

Comparison of the Reliability of Anatomic Landmarks based on PA Cephalometric Radiographs and 3D CT Scans in Patients with Facial Asymmetry.

IntroductionConventional cephalometry is an inexpensive and well-established method for evaluating patients with dentofacial deformities. However, patients with major deformities and in particular asymmetric cases are difficult to evaluate by conventional cephalometry. Reliable and accurate evaluation in the orbital and midfacial region in craniofacial syndrome patients is difficult due to inherent geometric magnification, distortion and the superpositioning of the craniofacial structures on cephalograms. Both two- and three-dimensional computed tomography (CT) have been proposed to alleviate some of these difficulties.Aims and objectivesThe aim of our study is to compare the reliability of anatomic cephalometric points obtained from the two modalities: Conventional posteroanterior cephalograms and 3D CT of patients with facial asymmetry, by comparison of intra- and interobserver variation of points recorded from frontal X-ray to those recorded from 3D CT.Materials and methodsThe sample included nine patients (5 males and 4 females) with an age range of 14 to 21 years and a mean age of 17.11 years, whose treatment plan called for correction of facial asymmetry.All CT scans were measured twice by two investigators with 2 weeks separation for determination of intraobserver and interobserver variability. Similarly, all measurement points on the frontal cephalograms were traced twice with 2 weeks separation. The tracings were superimposed and the average distance between replicate points readings were used as a measure of intra- and interobserver reliability. Intra-and interobserver variations are calculated for each method and the data were imported directly into the statistical program, SPSS 10.0.1 for windows.ResultsIntraobserver variations of points defined on 3D CT were small compared with frontal cephalograms. The intraobserver variations ranged from 0 (A1, B1) to 0.6 mm with the variations less than 0.5 mm for most of the points.Interobserver variations of points between first and second tracings defined on PA Ceph and 3D CT were less than 1.5 mm for all the points.A direct comparison of frontal cephalometry and 3D CT using intraobserver variation for the first observer showed that 3D CT was more reliable than frontal cephalometry for 11 points.Direct comparison of frontal cephalometry and 3D CT for the second observer showed a similar tendency with 14 points significantly more reliable for 3D CT.Comparison of frontal cephalometry and 3D CT using interobserver variation for the tracings showed that 3D CT was more reliable than frontal cephalometry.Summary and conclusionThe study has shown that 3D CT is consistently more accurate and reliable than conventional frontal cephalometry. Unfortunately, the cost of a computerized tomography examination is considerable; this means that, at this stage, its use by surgeons and orthodontists is a last resort.

Análise da fidelidade do traçado predictivo em pacientes submetidos à cirurgia ortognática em mandíbula

OBJETIVO: a proposta desse trabalho foi analisar a fidelidade dos traçados predictivos realizados para cirurgias ortognáticas, por meio de análise cefalométrica do pré e pós-operatório de sete dias, em pacientes submetidos à correção de deformidade mandibular. MÉTODOS: foram utilizadas telerradiografias cefalométricas de perfil de 17 pacientes submetidos à cirurgia ortognática de mandíbula. Foram realizados traçados cefalométricos do pré e do pós-operatório de 7 dias com marcação dos pontos côndilo (Co), pogônio (Pog), goníaco (Go), mento (Me), ponto B (B) e incisivo (I). A análise foi baseada na diferença obtida pela sobreposição dos traçados pré-operatório, predictivo e pós-operatório. Os pontos foram projetados em um plano cartesiano para medição das suas distâncias em milímetros. Os dados obtidos foram submetidos à análise estatística por meio do teste t de Student pareado (± = 0,05). RESULTADOS: no eixo horizontal, foi observada diferença média, entre a mudança planejada e a obtida nos traçados cefalométricos pós-operatórios, estatisticamente significativa nos pontos Pog (p = 0,014) e I (p = 0,008). No eixo vertical, não verificou-se diferença estatística significativa para os pontos cefalométricos marcados (p &gt; 0,05). CONCLUSÕES: o traçado predictivo contribuiu para a avaliação pré-operatória do paciente e, consequentemente, para a otimização do tratamento. Entretanto, ele não se mostrou totalmente fiel nos casos analisados, com leve subestimação das alterações esqueléticas horizontais. Essas alterações devem ser consideradas no planejamento e acompanhamento pós-operatório dos pacientes submetidos à cirurgia ortognática em mandíbula.

Paraconsistent Artificial Neural Network as Auxiliary in Cephalometric Diagnosis

This work presents an application of the paraconsistent artificial neural network (PANN) in the analysis of cephalometric variables and provides an orthodontic diagnosis. An expert's analysis is subject to the inherent imprecision of measurements, registers, and individual variability of physician visual analysis. Patient input cephalometric values are compared with means drawn from individuals considered normal in the cephalometric point of view by the PANN. This reference is constituted by individuals from 6 to 18 years old, both genders. The applied cephalometric analysis was targeted to measure skeletal and dental discrepancies and established a cephalometric diagnosis. The analysis results in degrees of skeletal, anteroposterior, and dental discrepancy, pertinent to upper and lower incisors. A sample of 120 orthodontic patients was processed by the proposed model and three orthodontic experts. Comparisons between the model and the human expert's performance provided kappa indexes that varied from moderate to almost perfect agreement. The agreement between the model and specialist's performance was equivalent. In addition, the model pointed out contradictions presented in the data that were not noticed by the orthodontists, which highlight the contribution that this kind of system could carry out in the orthodontics decision support.

Evolution of the incisal relationship in a Central European population (1870/1970)

Recent studies have supported the hypothesis that there is a tendency to evolution in the occlusal relationships of urban populations. Due to its role in the stomatognathic system and the hypothesis of the role of deep overbite in the appearance and development of TMD, particular interest is given to the incisal relationship and its evolution in urban populations. Incisal situation and relationship can be studied with anthropometric and cephalomatric determinants. This study compares the incisal relationship of two groups of young Caucasian adults born in 1870 and 1970, respectively. Twenty-four anthropometric and cephalometric points were analyzed for 30 subjects from each group. A statistically significant difference between the 1870/1970 samples was found for the following criteria (p<0.001): overbite: 1.17/3.81, position of the free edge of the mandibular incisor, sagittal values (orthodontic norm PAO) 78.75 mm/82.88 mm, position of the free edge of the mandibular incisor, vertical values 54.74 mm/58.87 mm, FMIA angle: 65.97°/58.4° and Angle classes: difference in distribution of the skeletal classes (Classes I, II and III) between the two populations (increase in Class II, 1970). Within the limits of this study results show a remarkable increase in overbite, a tendency towards a reduced prevalence of class III malocclusions and an increased prevalence of Class II malocclusions with vestibular position of the mandibular incisors.

Accuracy of cephalometric landmarks on monitor-displayed radiographs with and without image emboss enhancement

The aim of this study was to evaluate the accuracy of some commonly used cephalometric landmarks of monitor-displayed images with and without image emboss enhancement. The following null hypothesis was tested: there is no improvement in landmark detection accuracy between monitor-displayed images, with and without image embossing enhancement. Forty lateral cephalometric radiographs, taken from the data files of subjects were used in this study. A purpose-made software allowed recording of the cephalometric points and then, with the help of algorithms based on cellular neural networks, to transfer the previously processed radiographs into an embossed image. Five observers recorded 22 landmarks on the displayed images from the two image modalities, i.e. monitor-displayed radiograph (mode A) and monitor-displayed embossed radiograph (mode B). The positions of the landmarks were recorded and saved in the format of x and y co-ordinates and as Euclidean distance. The mean errors and standard deviation of landmarks location according to the two modalities were compared with the 'best estimate' for each landmark and the values were calculated for each of the 22 landmarks. One-way analysis of variance was then used to evaluate any statistically significant differences. Euclidean distance mean errors were higher for the embossed images (except for Po) than for the unfiltered radiographs. These differences were all statistically significant (P < 0.05) except for Or, Po, PM, Co, APOcc, and PPOcc. On the x and y co-ordinates, the accuracy of the cephalometric landmark detection improved on the embossed radiograph but only for a few points (Or on x axis and Po, PM, Co, and APOcc on y axis), as these were not statistically significant. The use of radiographic enhancement techniques, such as embossing, does not improve the level of accuracy for cephalometric points detection. Unless more precise algorithms are designed, this feature should not be used for clinical or research purposes.