Dissertations / Theses on the topic 'Cephalograms'

Thesis (M.S.)--University of North Carolina at Chapel Hill, 2007.
Title from electronic title page (viewed Dec. 18, 2007). "... in partial fulfillment of the requirements for the degree of Master of Science in the Department of Diagnostic Sciences and General Dentistry, School of Dentistry." Discipline: Diagnostic Sciences and General Dentistry; Department/School: Dentistry.

Oral Biology
M.S.
There remains a discord among orthodontists regarding the usefulness of a lateral cephalogram radiograph as a part of diagnostic records for treatment planning. Today, orthodontists take diagnostic lateral cephalograms largely based on a personal preference, rather than following any evidence-based approached for determining whether taking the radiograph will affect treatment planning. The aim of this study is to identify patients with the type of malocclusion for which the availability of a lateral cephalogram radiograph will affect the treatment plan. This would prevent patients, whose treatment plan would not benefit from a diagnostic lateral cephalogram, from receiving unnecessary ionizing radiation. The data for this study was obtained from responses to two questionnaires, mailed five weeks apart, to ten orthodontists with clinical experience. Primarily, the orthodontists were required to treatment plan twenty cases, twice, once with full diagnostic records including a lateral cephalogram radiograph and once without. Six orthodontists completed both questionnaires. Based on the data, it was found that for approximately 25% of patients having a lateral cephalogram radiograph does affect treatment planning. These patients present with bilateral, sagittal dental malocclusions, matching significant soft-tissue profile disharmony and at least one arch with a moderate arch length discrepancy. A larger, follow-up study is suggested to further investigate the relationship between malocclusion, lateral cephalogram radiographs, and treatment planning.
Temple University--Theses

Objetivo: O desenvolvimento da tecnologia em diagnóstico odontológico por imagem através dos Tomógrafos Computadorizados por Feixe Cônico, tornou possível e acessível a avaliação cefalométrica através de reconstruções volumétricas do crânio. Parâmetros baseados em evidências científicas são necessários para implementar o seu uso. Alguns parâmetros utilizados na cefalometria convencional (bidimensional) deverão ser esquecidos, outros deverão ser adaptados, outros, ainda, deverão ser criados. Propomos aqui a criação de um Cefalostato Virtual para orientação do crânio em TC, com a utilização de pontos intracranianos, que são mais estáveis. Também propomos a criação do ponto TS e da linha TS-Pg em substituição ao ponto S e ao eixo Y de crescimento de Downs, respectivamente. Além disso, propomos a linha Ba-Op como referência para casos de assimetria faciais onde não é possível a utilização do plano Horizontal de Frankfurt, em casos, por exemplo, de síndromes que afetem os pontos de referências mais externos. Métodos: 49 crânios pertencentes ao do Museu de Anatomia UNIFESP, foram escaneados em um tomógrafo computadorizado por feixe cônico (TCFC), na clínica ISOOrthographic, São Paulo. As pontuações foram realizadas em dois momentos, com espaçamento de uma semana. Foram calculadas estatisticamente medidas-resumo (média, quartis, mínimo, máximo e desvio padrão). Foram calculadas também as correlações intraclasse e correlações de Pearson entre o Eixo Y (S-Gn) e linha entre os pontos TS e Pg. Resultados: Apesar de se observar uma baixa reprodutibilidade nas coordenadas, para os pontos CE, Pg e Gn, foi observada alta correlação entre as medidas angulares em questão. Para descrever a inclinação do Eixo Y em função da inclinação da Linha TS e Pg adotou-se um modelo de regressão linear simples descrito pela equação abaixo: Ang Sö- Gn = 0,989 Ang TS Pgi i Conclusões: o uso do Cefalostato Virtual na orientação de Crânios em Tomografia Computadorizada é factível e favorece a reprodução do posicionamento craniano; apesar da baixa reprodutibilidade intra observador dos pontos CE, Pg e Gn, novos critérios tridimensionais na definição destes pontos poderiam aumentar a precisão na sua localização; a alta reprodutibilidade intra observador para os pontos Op, TS e N, sugere que os critérios anatômicos próprios das estruturas estudadas favorecem a sua determinação; o ponto TS apresentou maior reprodutibilidade do que o ponto S, embora esta diferença não tenha sido estatisticamente significante, podendo-se substituir o ponto S pelo TS em estudos futuros; existe alta correlação entre a linha entre os pontos TS e Pg e o Eixo Y; a avaliação do comportamento da inclinação da linha orbitomeática (HF) com relação à linha Básio-Opístio sugere que na presença de alterações cranianas este relacionamento propicie auxílio no diagnóstico das alterações craniofaciais.
Objective: The development of new technology in dental diagnosis by cone beam CT (CBCT) image, made possible and accessible the realization of cephalometric evaluation through volumetric reconstructions of the skull. Scientific parameters with evidence-based are needed to implement its use. Some parameters used in conventional cephalometry (2D) maybe need to be forgotten, others should be adapted, and others still to be created. In this research we propose to create a Virtual Cephalostat orientation of the skull in CT, with the intracranial landmarks, because they are more stable. We propose the creation of landmark TS (Tubercle Sella) and the TS-Pg line to replace the landmark S (Sella) and the Y-axis of growth (Downs), respectively. Furthermore, we propose to use the Basion-Opistion line as a reference for cases of craniofacial asymmetry where is not possible to use the Frankfurt horizontal plane, as in some cases of syndromes that affects the most external landmarks. Methods: 49 skulls of Anatomy Museum of UNIFESP Federal University of São Paulo, were scanned in a CBCT. The analyses were performed in 2 stages, within 1-week space. Statistics measurements were calculated (mean, quartiles, minimum, maximum and standard deviation). We also calculated the intraclass correlations (ICC) and the Pearson correlations between the Y axis (S-Gn) and the line between landmarks TS-Pg. Results: Even if there is a low reproducibility in the coordinates for landmarks EC (Ethmoidal Crest), Pg and Gn it was observed a high correlation between the angular measures in question. To describe the inclination of the Y axis according to the slope of the line adopted TS and Pg a simple linear regression model is used, showed by the equation bellow: Ang Sö- Gn = 0,989 Ang TS Pgi i Conclusions: The use of the Virtual Cephalostat in orientation of skulls using CBCT is feasible and facilitates the reproduction of the skull position, despite the low intra observer reproducibility of landmarks EC, Pg and Gn, new 3D criteria in the definition of these landmarks could increase the precision in its location. The high intra observer reproducibility at the landmarks Op, N and TS, suggests that the anatomical criteria themselves promote their reliability; The TS landmark showed a higher reproducibility than the S landmark, even though the difference was not statistically significant, and it should be replaced by the landmark TS in future studies. There is a high correlation between the TS - Pg line and Y-axis. The relationship between the slope of the HF plane and Ba -Op line suggests that in the presence of the alteration of morphology in craniofacial structure, this relationship offer help in the diagnosis of craniofacial changes.

Oral Biology
M.S.
Introduction: Controversy exists over the value of a lateral cephalogram for treatment planning in different malocclusion types. Discord has been found in the literature, and no studies on the matter have focused solely on Class I dental malocclusions. The aim of this study was to elucidate whether treatment decisions of extraction or non-extraction and the perceived need for a lateral cephalogram would change depending on whether a lateral cephalogram was provided or eliminated in the patient record set. Methods: A survey was distributed to a random sample of AAO members. The survey consisted of four different patient record sets, each with a Class I dental malocclusion. Each record set had two versions—one with the lateral cephalogram and one without. The survey had randomization of each version of the record sets so that each record set would be viewed an equal number of times with and without its corresponding cephalogram. Subjects were then asked a series of four questions pertaining to each case: was a cephalogram necessary for treatment planning, treatment of extraction versus non-extraction, retention method, and if records were adequate to treatment plan. Results: In total, 79 orthodontists completed the survey. For all cases combined, record sets viewed with the lateral cephalogram had an increase in the: perceived need for a lateral cephalogram, decision of extraction, and opinion of the records being adequate to treatment plan. All were statistically significant at P ≤ 0.001. For each record set, the difference in perceived need for a lateral cephalogram was statically significant. Conclusions: The use of a lateral cephalogram for diagnosing and treatment planning seems to hold value in Class I dental malocclusions, justifying radiation exposure for this diagnostic record. Additionally, the perceived need for a lateral cephalogram is greater when it is presented with the record sets, demonstrating the diagnostic value this radiograph holds.
Temple University--Theses

Les travaux presentes dans ce memoire de these concernent la definition d'un ensemble de modeles coherents, pour l'identification semi-automatique des points cephalometriques figurant sur des radiographies du profil de la face, en orthodontie. Le systeme de reconnaissance de formes que nous proposons est base sur l'utilisation d'un modele de contours deformables associes aux contours recherches. L'elaboration de ce systeme nous conduit tout d'abord a definir un modele de prelocalisation des contours deformables et d'estimation de la position des points a identifier, en fonction de l'enrichissement du modele au fur et a mesure de la detection des points. Cette recherche est basee sur un maillage aux elements finis, constitue d'elements barre. Lors de la phase de pretraitement d'une radiographie, la forme du maillage est adaptee au profil cranien etudie, a partir des conditions limites portant sur trois points, et d'un modele d'adaptation de formes. Les modeles de contours deformables, judicieusement lies au maillage, sont prepositionnes sur l'image en mode solide puis se deforment sous l'action d'efforts exerces par les gradients des niveaux de gris de l'image. Les deformations du contour sont operees en exploitant la theorie des poutres en resistance des materiaux, a partir de l'equation differentielle de la deformation de la ligne moyenne d'une poutre soumise a un torseur d'efforts

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The present study consisted of evaluating dental, skeletal and tegumentary changes promoted by fixed orthodontic treatment with two-step retraction anterior, by means of lateral cephalograms. To this end, we selected 14 patients who required extraction of four premolars, all with Class I malocclusion. The anterior retraction was performed by the retraction of canine (prior to incisors bonding) and of incisors. Twelve patients did not use any device for anchoring. Lateral cephalograms were examined at the beginning and end of canine retraction and by the end of the fixed orthodontic treatment. Cephalograms were scanned to obtain cephalometric measurements using the software Radiocef® (RadiomemoryR- Belo Horizonte, Brazil). Data were submitted to analysis of variance and Tukey s test (p<0.05). Results indicated few skeletal changes, except for a slight retraction of the point A, and increase in mandibular length, in lower-anterior and total facial height, and slight mandibularcounterclockwiserotation due to the craniofacial growth. After canine retraction, there was a lingual inclination and retrusion of upper and lower incisors, which remained stable to the upper incisors at the end of the treatment. In the same period,the lower incisors retruded with a slope similar to the initial. Besides that, no significant loss of anchoring was detected. These dental changes resulted in retrusion of upper and lower lips after canine retraction, and the lower lip continued to retract by the end of the treatment. In conclusion, the treatment using two-step retraction anterior did not lead to a significant loss of anchoring, and reduced the facial convexity.
O objetivo do presente estudo consistiu em avaliar as alterações dentoesqueléticas e tegumentares promovidas pelo tratamento ortodôntico fixo com a retração anterior em duas fases, por meio de telerradiografias em norma lateral. Foram selecionados 14 pacientes com idade média de 14,6 anos que necessitavam de extrações dos quatro primeiros pré-molares, todos apresentando má oclusão de Classe I. A retração anterior foi realizada inicialmente pela retração dos caninos (previamente à colagem dos incisivos) e subsequentemente, pelos incisivos. Doze pacientes não utilizaram qualquer dispositivo para ancoragem e dois pacientes utilizaram como ancoragem o Arco Extra-Bucal (AEB) de uso noturno. Foram avaliadas as telerradiografias em norma lateral ao início, final da retração dos caninos e final de tratamento ortodôntico fixo. As telerradiografias foram escaneadas e mensuradas por meio do programa Radiocef® (RadiomemoryR- Belo Horizonte, Brasil). Os dados foram submetidos à Análise de Variância e teste de Tukey (p<0,05). Os resultados demonstraram poucas alterações esqueléticas, exceto por uma retrusão suave do ponto A e aumento do comprimento mandibular, da altura facial ântero-inferior e total e rotação suave anti-horária mandibular devido ao crescimento craniofacial. Após a retração dos caninos, houve uma inclinação para lingual e retrusão dos incisivos superiores e inferiores, que permaneceram estáveis para os incisivos superiores no período final de tratamento. Já os incisivos inferiores neste mesmo período, retruíram mais com uma inclinação semelhante àquela inicial. Além disso, não houve perda de ancoragem de forma estatisticamente significante. Estas alterações dentárias refletiram em retrusão dos lábios superior e inferior após a retração dos caninos, sendo que o lábio inferior continuou a retrair no período final de tratamento. Conclui-se que o tratamento com a retração em duas fases não representou perda de ancoragem estatisticamente significante, além de diminuir a convexidade facial.

BACKGROUND: Growth of the cranial base and its structures are of particular interest to the orthodontic community. The midface and nasal bones have a significant influence on facial esthetics and thus pattern recognition of facial growth from parental data can influence orthodontic treatment plans. We aimed to determine if there is a similarity in midface and nasal bone and soft tissue growth between a child and either parent. MATERIALS AND METHODS: This cross-sectional study was comprised of forty-seven western European families from the Forsyth/Moorrees Twin Study. The lateral cephalograms of each parent and post pubertal child, who were at least 2 years past peak growth (age ≥ 16 yrs for females and ≥ 17 yrs for males) were evaluated on fourteen cephalometric variables. The radiographs were digitized and analyzed using the Mimics™ software program (Materialise, Leuven, Belgium) by a single investigator. A linear regression analysis was used to correlate linear and angular measurements to one another. An ANOVA with multiple comparisons (TUKEY) was performed to test for the differences between family members controlling for the effect of the individual family (as each family has a trend within itself). Age and gender interactions were tested for in the models. Statistical significance was set at p < 0.05. RESULTS: Twenty-five male and twenty-two female children and their parents were studied. When comparing the fourteen parameters between the mean of the child and both parents, a significant difference (p < 0.05) was found between the child and the father but not the mother in six measurements. These included the ratio of nasal height to total face height, angle of nasal bone to SN, distance from rhinion to pronasale (mm), distance from ANS to pronasale (mm), projection of nose (mm) and nasal length (mm). A significant difference was also found between the child and the mother, but not the father for rhinion to ANS (mm). A significant difference was found between the child and both parents for nasal height (mm). When controlling for family and isolating the gender of the child, males and females were not significantly different from their fathers for ratio of nasal height to total face height. For angle of nasal bone (S-N-Rh) and nasal length (N’-vertical line from Pro), females but not males were significantly different from the father. Both girls and boys were still significantly different from the father in the rhinion to pronasale and ANS to pronasale distances, projection of nose and nasal heights. Only males showed a significant difference from the mother for rhinion to ANS and nasal height when isolated for by gender. CONCLUSION: Statistically significant differences were found between the child and father and not the mother for six out of our fourteen measurements of interest. Two measurements of interest showed a difference between the child and the mother and not the father and one showed a significant difference from both parents. From this study we conclude that children tend to be morphologically less similar to their fathers when comparing midface and nasal soft and hard tissue parameters.

碩士
中臺科技大學
放射科學研究所
99
Object: The aim of the study was to examine the intraobserver reliability of landmark identification in cone beam computed tomography (CBCT)-synthesized two-dimensional (2D) lateral cephalograms versus conventional digital cephalograms. Materials and methods: Twenty CBCT scans and the corresponding conventional lateral cephalgrams were randomly selected. Two-dimensional lateral cephalograms were constructed from the three-dimensional (3D) CBCT scans by summing the voxels of the entire volume. All the images were imported into Winceph 8.0. Twenty landmarks in the CBCT-synthesized 2D cephalograms and conventional cephalograms were identified directly on the computer screen by an experienced orthodontist and the operation was repeated two weeks later. The x- and y-coordinates of each landmark were examined for intraobserver reliability. The differences in landmark reproducibility between the two modalities were analyzed with paired Student’s t-test. Results: The horizontal and vertical errors of landmark identification by the two modalities of cephalometry ranged from 0.18 to 1.67 mm. Fewer landmarks in CBCT-synthesized cephalograms had intraobserver error greater than 1 mm. Significantly better reliability was observed in CBCT-synthesized cephalograms at Me, LIE and LIA in the horizontal dimension and at Pog, Gn, Me, UIA, LIA and LM in the vertical dimension. Scatter-plots revealed a characteristic pattern of error distribution for each landmark. Conclusions: CBCT-synthesized lateral cephalograms is a promising method to replace conventional cephalograms for orthodontic diagnosis.

碩士
國立成功大學
醫學工程研究所
86
Automated Image Registration for Cephalometry Ming-lung Chien* and Kuo-sheng Cheng** Institute of Biomedical Engineering National Cheng Kung University, Taiwan, R.O.C. Abstract Spatial change of craniofacial structures for evaluating the effects of the orthodontic treatment or surgery is always base on superimposition of cephalometric tracings taken at different times. A variety of methods upon different reference structures within the skull have been proposed for clinical use. The orthodontists must be careful in recognizing the same feature for the two cephalograms by manual method. The errors involved in the measurement of superimposition may be resulted due to following reasons: 1. The bad quality of X-ray film; 2. The change of structure shape caused from bone remodeling;3. The experience of orthodontists. Thus, different conclusions may be drawn by individual orthodontics about the treatment of surgey.In the study of superimposition will be computerized. This procedure contains three parts: 1. To digitize and calibrate the images taken from the CCD camera; 2. To extract the features inside the parts of image. Firstly, the cranial base curve is extracted by the best oriental edge detector and Hough transform. Secondly, the mandibular curve is extracted by the Laplacian of Gaussian and grouping. 3. To automate the superimposition based upon the one of clinically available process, and finally to display the superimposed images on the screen and the related results. cluster space and correlation coefficient are used. The study had finished results included that automatically extracted the cranial base curve, the lower border curve of the mandible and automatically superimpose. Because the curve of maxillary is not extracted by applicable algorithms, correlation coefficient is directly used to superimpose. The completely procedure typically takes 5~6 minutes. The orthodontists take 30~40minutes by manual method. The accuracy of the cranial base is 0.312cm, and the mandible is 0.005cm. The difference between the curve extracted by the system and orthodontists manipulate plots is 1.13cm on the cranial base, 0.909cm on the maxillary, and 1.22cm on the mandible.

碩士
國立成功大學
口腔醫學研究所
93
Postero-anterior and lateral cephalograms have been widely used in diagnosis and assessment of treatment results in orthodontics and orthognathic surgery. Although the two views can provide plenty clinical information in two dimensions, they cannot accurately demonstrate the anatomic structures in 3 dimensional aspects and may cause measurement errors due to the distortion of 2D films. The aims of this study were to reconstruct 3D model by using biplanar cephalograms with orthogonal projection and to compare the differences between 3D and 2D analyses. The procedures were summarized as following: (1) To identify landmarks which could be used for 3D reconstruction, (2) To construct the norms of spatial information of the skull based on the error estimation from 3D reconstruction through computed tomography (CT), (3) To compare the differences between conventional 2D and 3D analyses, (4) To analyze the accuracy of the point selection procedure, and (5) To apply in clinics. We explored fifteen clear landmarks on both films and used them in this study. By comparing the data from CT and biplanar cephalograms, we found that the accuracy in this 3D reconstruction method was 98.8%, which was good enough for clinical application. The projection errors resulting from measurements on 2D films could be corrected successfully by 3D reconstruction with biplanar cephalograms. All of six examiners could precisely identify landmarks on films from a dry skull, but only two of them showed good accuracy in identifying landmarks on the same films. These two examiners showed poor precision in identification on films from clinical patients for landmarks such as OrR, OrL, Me, GoR and GoL, but good precision on tracing papers from the same films. On the other hand, the mean differences of landmark identification between the two examiners are greater than 1mm whether the observation is made directly on films or on papers through tracing. The study indicates that biplanar cephalograms with orthogonal projection can provide a clinically useful 3D analysis.

碩士
國立成功大學
醫學工程研究所碩博士班
96
In this study, the computerized system with a 3D head position monitoring device for automated landmarking of PA cephalogram is developed to reduce the projection error caused by head rotation. Firstly, the morphological feature parameters for craniofacial structure are obtained from the tracing images using Hough transform and linear regression. Then based on these parameters, the tracings are clustered using fuzzy c-means. For each class, the template and the ranges of landmarks distribution are computed from the superimposed tracings with least-square-error method. Secondly, the image enhancement and Hough transform are applied to cephalogram for obtaining the corresponding morphological features parameters. A template with the shortest distance is found and overlapped for landmarking. Through the morphological information and image processing technique, the actual positions of landmark are located. For the 3D head position monitoring device, a two-axis digital accelerometer and a digital compass are integrated to monitor the head position in real time. Via the Zigbee wireless module, the angle information is obtained for the orthodontist’s reference. In this study, a data set of 130 tracings is acquired and clustered into eight classes. Each class contains more than ten tracings. For the same class, the landmark distributions are all within 4 mm. Twenty two cephalograms are tested for evaluating the performance of proposed system. In comparison with the manual measurements, the average error of the automated landmarking system is less than 4 mm. For the head position measurement, the range of head rotation is from -2 to 3 degree during radiography. The orthodontist can measure the angles of head rotation to reduce the error of cephalometric radiography.

碩士
高雄醫學院
牙醫學研究所
87
Cephalometric study using FEM to compared 60 of Class Ⅲmalocclusion patients aged 8-17 years with their 60 counterparts of normal Class I occlusion was carried out. Twenty-four landmarks on the mandible were selected and digitized. The morphological differences between Class I and Class Ⅲ groups were then color-mapped to provide graphical displays. It is showed that Class Ⅲ malocclusion samples in this study were significant characterized with longer mandibular corpus, smaller condyle and coronoid process. Meanwhile, the prominence of size difference on chin area was observed, associated with maximum size difference localized on menton area. These morphological differences may contribute to the mandibular prognathism. The all parameters of size difference are more various than those in shape difference. Although there are some small differences between the mandibular morphology of male and female with Class Ⅲ malocclusion, the difference are not significant.

碩士
高雄醫學大學
牙醫學系碩士班
106
Purpose: The purpose of this study was to evaluate the relationship between the depth of the curve of Spee (CoS) and the different type of malocclusion in the adult population of Taiwanese, to determine whether the depth of the CoS is affected by different skeletal pattern or dental relation. Material and methods: Ninety lateral cephalograms and digital models of untreated patients were included and assigned to 3 malocclusion groups as Angle’s Class I, Class II and Class III malocclusion. The depth of the CoS and dental measurement were measured on digital models by 3shape OrthoAnalyzerTM. Liner and angular measurements on digital lateral cephalograms by Viewbox3® will also be carried out. Multiple liner regression and other statical analysis were used to detect the correlation between CoS and lateral cephalometric analysis. Results: No significant differences were found in the depth of CoS between male and female or right and left side in all malocclusion. The depth of CoS was greatest in the Class II malocclusion followed by Class I and Class III malocclusion. There’s no significant correlation between cephalomateric analysis and the depth of CoS in Class I malocclusion. However, in Class II malocclusion, SNA and SN-FH were significant associated with CoS; In Class III malocclusion, Cd-Gn was significantly correlated with the CoS. In dental model analysis, overbite was the only one which significantly correlated with CoS in all malocclusion. Overjet also significantly associated with CoS in Class II malocclusion. Conclusion: The depth of CoS was greatest in the Class II malocclusion followed by Class I and Class III malocclusion. The CoS is influenced only to a minor extent by dentofacial morphology. Multiple linear regression analysis showed that the curve of Spee in the mandibular arch is significantly influenced by overbite.

Ziel dieser retrospektiven Studie war die Untersuchung verschiedener Wachstumsvorgänge im Ober- und Unterkiefer jugendlicher Patienten, speziell die der retromolaren Räume, am Fernröntgenseitenbild. Für diese Studie wurden insgesamt 305 Fernröntgenseitenbilder der Polikliniken für Kieferorthopädie der Universitätskliniken Leipzig und Dresden mittels der Software OnyxCeph³™ von Image Instruments ausgewertet. Mit dieser Studie konnte gezeigt werden, dass die retromolaren Räume im Alter von 9 – 16 Jahren durchschnittlich annähernd linear und bei beiden Geschlechtern in gleichem Maße zunehmen. Für den mandibulären retromolaren Raum wurde anhand der gewonnenen Durchschnittswerte die vereinfachte Formel Lebensalter + 12 in mm entwickelt. Damit ist eine Einschätzung des retromolaren Platzangebots anhand des Alters möglich. Fast alle vermessenen Strecken korrelieren signifikant mit dem chronologischen Alter, die höchste Korrelation besteht dabei für den retromolaren Raum des Unterkiefers. Neben bereits in anderen Studien zum Zwecke der Altersdiagnostik untersuchten Strecken, wie der Unterkieferlänge, kann zukünftig auch der retromolare Raum zur Altersschätzung anhand des Fernröntgenseitenbildes herangezogen werden. Verschiedene Autoren empfehlen zur Altersschätzung eine Kombination mehrerer Parameter. Mit drei in dieser Studie bestimmten Parametern konnte für beide Geschlechter eine Formel zur Altersschätzung aufgestellt werden. Der Standardschätzfehler beträgt jeweils 1,05 Jahre (Jungen) bzw. 1,28 Jahre (Mädchen).

Aim:To investigate the differences, if any, between tooth-anchored maxillary expansion (TME) and bone-anchored maxillary expansion (BME) in terms of the produced longitudinal dentoskeletal changes -and the stability of these changes- in adolescents with maxillary constriction. Methods:Sixty two suitable subjects were randomly assigned to one of three groups: (1) TME group; (2) BME group; (3) Control group. Lateral cephalograms, posteroanterior cephalograms, and dental casts were obtained at baseline and at three post-expansion time points. Records from all time points were analyzed. Results:There were no clinically significant differences between the TME and BME groups at any data collection time point. Both showed initial increases in dentoskeletal widths and dental tipping which were subsequently largely lost to relapse in the absence of retention. Conclusion:There are no clinically significant differences in the dentoskeletal changes -or the stability of these changes- produced by TME and BME in adolescents with maxillary constriction.