Ursula Hirschfelder

Enamel Demineralization during Fixed Orthodontic Treatment – Incidence and Correlation to Various Oral-hygiene Parameters

Objective:To investigate the incidence of white spot lesions (WSLs) around brackets and molar bands during orthodontic therapy, and establish whether a correlation to indices of dental and gingival health, fluoride application and oral hygiene could be demonstrated.Patients and Methods:Fifty-three patients with fixed orthodontic appliances were included at random in this study at the Department of Orthodontics of Erlangen-Nuremberg University. Dental health (DMFS), plaque index, papillary bleeding index, sulcus probing depth (SPD), gingival recession (GR), clinical attachment level (as sum of SPD and GR), oral hygiene, and fluoride use were evaluated. WSLs were graded from intraoral photographs taken before and after treatment.Results:97.5% of teeth before and 73.6% after treatment were free of WSLs. Of all teeth, 24.9% developed new WSLs or a rise in their number. New or more numerous WSLs were more common in upper and lower premolars (34.4%) and front teeth (28.1%) than molars (11.8%). WSL incidence during therapy correlated with clinical attachment level, and the oral hygiene and fluoride-use scores.Conclusions:Despite improvements in materials and preventive efforts, orthodontic treatment continues to carry the considerable risk of enamel demineralization. Each patients prophylactic efforts, including fluoride use, are of paramount importance in preventing WSLs.ZusammenfassungZiel:Ziel der Studie war es, die Inzidenz von „white spot lesions“ (WSLs) um Brackets und Molarenbänder während der kieferorthopädischen Behandlung festzustellen sowie zu prüfen, ob ein Zusammenhang mit Indices der dentalen und gingivalen Gesundheit, der Fluoridanwendung und der Mundhygiene zu erkennen ist.Patienten und Methodik:Es wurden 53 Patienten mit festsitzender Multibracketapparatur der Zahnklinik 3 – Kieferorthopädie der Universität Erlangen-Nürnberg randomisiert ausgewählt. Zahngesundheit (DMFS), Plaque-Index, Papillen-Blutungs-Index, Sondierungstiefe (SPD), gingivale Rezession (GR), klinischer Attachmentlevel als Summe aus SPD und GR, Mundhygienegewohnheiten sowie der Umfang häuslicher Fluoridanwendungen wurden erhoben. Der Grad der WSLs wurde anhand intraoraler Fotografien vor und nach der kieferorthopädischen Behandlung dokumentiert und bewertet.Ergebnisse:97.5 % der Zähne wiesen vor, 73.6% nach der Behandlung keine WSLs auf. Bei 24.9% aller Zähne entstanden neue oder ausgedehntere WSLs. Die Zunahme von WSLs betraf besonders die Prämolaren (34.4%) und die Frontzähne (28.1%), weniger die Molaren (11.8%) des Ober- und Unterkiefers. Die Inzidenz der WSL swährend der kieferorthopädischen Behandlung korrelierte mit dem klinischen Attachmentlevel und den Scores für Mundhygiene und Fluoridgebrauch.Schlussfolgerungen:Trotz der Weiterentwicklung der kieferorthopädischen Materialien und der Präventionsmaßnahmen birgt die festsitzende kieferorthopädische Therapie weiterhin ein erhebliches Risiko der Schmelzdemineralisation. Zur Prophylaxe bleibt die optimierte Mundhygiene der Patienten unter Einschluss der häuslichen Fluoridierung von wesentlicher Bedeutung.

Analysis of bone resorption after secondary alveolar cleft bone grafts before and after canine eruption in connection with orthodontic gap closure or prosthodontic treatment

PURPOSE We sought to analyze the success rate of secondary alveolar cleft bone grafts before and after canine eruption in connection with orthodontic gap closure or gap opening. PATIENTS AND METHODS Sixty-eight secondary alveolar cleft bone grafts with iliac crest spongiosa were carried out in 57 patients (mean age, 9 years; age range, 8 to 11 years) with 11 bilateral and 46 unilateral clefts of the lip, alveolus, or palate. Gap closures were carried out after 53 bone grafts (78%), and gap openings with subsequent dental implants were carried out with 15 bone grafts (22%). The parameters acquired radiologically (orthopantomograms) at the time of the surgery and the follow-up examination (mean age, 3 years; age range, 7 months to 9 years) were 1) bone resorption in relation to the interdental height of the alveolar process in the vicinity of the cleft and 2) root growth of the teeth in the vicinity of the cleft. The statistically significant differences (P <.05) were monitored with a software program. Resorption grades I and II (>50% of the interalveolar bone height) were considered to be a success. RESULTS Resorption was grade I in 69%, grade II in 19%, grade III in 10%, and grade IV in 1% of cases. Thus, the overall success rate was 88%. At the time of the osteoplasty, the root growth of the tooth in the immediate vicinity of the cleft was fully completed in 27 teeth (39%), three-quarters completed in 23 teeth (26.5%), and semicompleted in 18 teeth (33.8%). Twelve teeth (18%) in the vicinity of the cleft (lateral incisors/canine) remained unerupted and displaced after the surgery. It was necessary to expose unerupted teeth surgically to reposition them orthodontically. The resorption losses were significantly lower with gap closures than with gap openings (P <.001). However, bone grafts performed before canine eruption were largely carried out with the objective of orthodontic gap closure, in contrast to the bone grafts that were carried out after canine eruption (P <.02). CONCLUSION Gap closures provide more favorable results than do gap openings in regard to resorption. Controlled dental eruptions or orthodontic gap closures reduce the graft resorption. The exact timing of surgery proved to be only a secondary consideration.

Three-dimensional Analysis of Facial Symmetry in Cleft Lip and Palate Patients Using Optical Surface Data

Aim:Presentation of a new technique to determine the plane of symmetry of a face, and to assess the degree of facial symmetry in patients with unilateral cleft lip and palate based on three-dimensional (3D) optical surface data.Patients and Methods:After having determined a plane of symmetry according to optical 3D facial surface data, we identified differences in landmarks, the surface areas of the upper lip vermilion and nostrils and virtual volumes of the midface, nose and upper lip for cleft and unaffected sides in forty 10-year-old patients suffering from complete unilateral cleft lip, alveolus and palate. The children had undergone lip repair via the Tennison-Randall technique and had received subsequent orthodontic treatment (but not secondary osteoplasty).Results:Statistically significant differences were apparent between cleft and non-cleft sides in terms of the nasal landmarks, nostril angle and virtual volume of the nose. The upper lip was symmetrical when cleft and non-cleft sides were compared.Conclusions:This new technique of symmetry analysis reveals that the noses of 10-year-old patients with complete unilateral cleft lip and palate who had not undergone revisional surgery present a measurable and significant degree of asymmetry, while the upper lip is symmetrical as a consequence of interdisciplinary treatment by orthodontists and oral and maxillofacial surgeons. Further 3D analyses on larger numbers of patients will allow more comprehensive and consistent analysis of the potential and limitations of various surgical and conservative methods so as to identify those techniques with the best outcome in terms of facial symmetry.ZusammenfassungZiel:Ziel der Studie war es, eine neue Technik zur Beurteilung der Symmetrieebene des Gesichts auf Basis dreidimensionaler Datensätze vorzustellen und ihre Anwendung bei Patienten mit einseitiger Lippen-Kiefer-Gaumen-Spalte zu demonstrieren.Patienten und Methodik:Bei vierzig 10-jährigen Patienten mit einseitiger, vollständiger Lippen-Kiefer-Gaumen-Spalte, die bisher keine sekundäre Osteoplastik erhalten hatte, aber alle kieferorthopädisch behandelt wurden, erfolgte mit Hilfe von optischen 3-D-Daten der Gesichtsoberfläche und einer spezialisierten Software die Bestimmung der Symmetrieebene. Danach wurden die Unterschiede zwischen Landmarken, Flächen des Lippenrots und der Nasenlöcher sowie virtueller Volumina des Mittelgesichts, der Nase und der Oberlippe getrennt nach Gesichtshälften berechnet.Ergebnisse:Zwischen der Gesichtshälfte mit Spaltbildung und der Seite ohne Spalte bestanden statistisch signifikante Unterschiede in Bezug auf Landmarken, Winkel, Flächen und Volumina der Nasen. Im Bereich der Oberlippe wurden keine statistisch signifikanten Unterschiede zwischen der Spaltseite und der nicht betroffenen Seite bestimmt.Schlussfolgerungen:Die vorgestellte Technik der Symmetrieanalyse zeigt beim vorliegenden Patientengut, dass 10-jährige Patienten mit einseitiger Lippen-Kiefer-Gaumen-Spalte, die keine Korrekturoperationen im Verlauf erhielten, eine messbare, statistisch signifikante Asymmetrie der Nase aufweisen. Die Oberlippe dagegen ist bedingt durch das interdisziplinäre Behandlungskonzept aus kieferorthopädischen und mund-, kiefer- und gesichtschirurgischen Maßnahmen symmetrisch. Weitere dreidimensionale Analysen einer größeren Anzahl von Patienten werden die Möglichkeiten und Grenzen der verschiedenen operativen und konservativen Behandlungsmöglichkeiten herausstellen und die Auswahl des Behandlungskonzeptes erleichtern, das in Bezug auf die Gesichtssymmetrie mit den besten Ergebnissen aufwartet.

Comparison of the Spatial Landmark Scatter of Various 3D Digitalization Methods

AimThe aim of this study was to compare four different threedimensional digitalization methods on the basis of the complex anatomical surface of a cleft lip and palate plaster cast, and to ascertain their accuracy when positioning 3D landmarks.Material and MethodsA cleft lip and palate plaster cast was digitalized with the SCAN3D® photo-optical scanner, the OPTIX 400S® laser-optical scanner, the Somatom Sensation 64® computed tomography system and the MicroScribe® MLX 3-axis articulated-arm digitizer. First, four examiners appraised by individual visual inspection the surface detail reproduction of the three non-tactile digitalization methods in comparison to the reference plaster cast. The four examiners then localized the landmarks five times at intervals of 2 weeks. This involved simply copying, or spatially tracing, the landmarks from a reference plaster cast to each model digitally reproduced by each digitalization method. Statistical analysis of the landmark distribution specific to each method was performed based on the 3D coordinates of the positioned landmarks.ResultsVisual evaluation of surface detail conformity assigned the photo-optical digitalization method an average score of 1.5, the highest subjectively-determined conformity (surpasssing computer tomographic and laser-optical methods). The tactile scanning method revealed the lowest degree of 3D landmark scatter, 0.12 mm, and at 1.01 mm the lowest maximum 3D landmark scatter; this was followed by the computer tomographic, photo-optical and laser-optical methods (in that order).ConclusionsThis study demonstrates that the landmarks’ precision and reproducibility are determined by the complexity of the reference-model surface as well as the digital surface quality and individual ability of each evaluator to capture 3D spatial relationships. The differences in the 3D-landmark scatter values and lowest maximum 3D-landmark scatter between the best and the worst methods showed minor differences. The measurement results in this study reveal that it is not the method’s precision but rather the complexity of the object analysis being planned that should determine which method is ultimately employed.ZusammenfassungZielDas Ziel der vorliegenden Studie bestand darin, anhand der anatomisch komplexen Oberfläche eines Lippen-Kiefer-Gaumen-(LKG-)Spalten-Gipsmodells vier verschiedene räumliche Digitalisierungsverfahren einander gegenüberzustellen und deren Genauigkeit bei der 3-D-Messpunktpositionierung festzustellen.Material und MethodikDazu wurde ein LKG-Spalten-Gipsmodell mit dem lichtoptischen Scanner SCAN3D®, dem laseroptischen Scanner OPTIX 400S®, dem Computertomographen Somatom Sensation 64® und dem dreiachsigen taktilen Digitalisierungsarm MicroScribe® MLX digitalisiert. Zunächst wurden durch vier Auswerter für die drei nichttaktilen Verfahren die subjektive Oberflächendetailtreue im Vergleich zum Referenz-Gipsmodell visuell beurteilt und benotet. Anschließend wurde von den vier Auswertern eine Messpunktpositionierung in fünf Durchgängen im Abstand von 2 Wochen wiederholt durchgeführt. Dabei sollten die Messpunktpositionen lediglich von einem Referenzmodell aus Gips auf das durch das entsprechende Verfahren digital reproduzierte Modell übertragen bzw. räumlich ertastet werden. Anhand der räumlichen Koordinaten der gesetzten Messpunkte erfolgte die statistische Prüfung der verfahrensspezifischen Messpunktstreuung.ErgebnisseDie visuelle Beurteilung der Oberflächendetailtreue bescheinigte der lichtoptischen Digitalisierungsmethode mit der Durchschnittsnote 1,5 vor dem computertomographischen und laseroptischen Verfahren die höchste subjektiv wahrgenommene Genauigkeit. Für die taktile Abtastung der Messpunkte konnte mit 0,12 mm die geringste räumliche Messpunktstreuung und mit 1,01 mm die kleinste maximale räumliche Messpunktabweichung festgestellt werden. Danach folgten das computertomographische, lichtoptische und laseroptische Verfahren.SchlussfolgerungenDie vorliegende Studie verdeutlicht, dass die Genauigkeit und Reproduzierbarkeit der Messpunkte nicht nur von der Komplexität der Referenzmodelloberfläche, sondern auch von der digitalen Oberflächengüte und des damit verbundenen individuellen räumlichen Erfassungsvermögens des einzelnen Auswerters bestimmt wird. Die Differenzen der Messwerte der räumlichen Messpunktabweichung und die der kleinsten maximalen räumlichen Messpunktabweichung zwischen dem besten und dem schlechtesten Verfahren zeigten nur geringe Unterschiede. Die Ergebnisse ließen den Schluss zu, dass nicht die Methodengenauigkeit, sondern die Komplexität der durchzuführenden Objektanalyse die Verfahrenswahl bestimmen sollte.

Variance of landmarks in digital evaluations: comparison between CT-based and conventional digital lateral cephalometric radiographs.

Aim:The aim of this study was to examine whether bony, dental and soft tissue landmarks could be placed in CT-based lateral cephalograms with the same precision as in conventional digital lateral cephalograms.Materials and Methods:Nine patients without craniofacial dysplasia (2 female, 7 male, aged 12.8–32.3) who had undergone a lateral cephalogram and CT examination within an interval of a maximum of 6.5 months were selected in retrospect. The lateral cephalograms were done with the ORTHOPHOS Plus DS Ceph®, and the CT examination with the SOMATOM Sensation® 16 or 64 scanner. The CT-based cephalograms were generated with the VoXim® 4.3 program based on axial CT reconstructions in the bone window. The cephalograms were analyzed using the Onyx Ceph® 2.7 software by 2 orthodontists and 5 postgraduate students, each cephalogram being examined five times by each examiner on different days. Statistics were compiled with SPSS 13.0 and 14.0 based on the deviation from the individual mean value of each landmark.Results:The descriptive statistics showed in the conventional cephalogram, averaged over all 61 landmarks, a mean quartile range of on average 0.62 mm in the horizontal and 0.67 mm in the vertical axes. The CT-based cephalograms ranged between 0.64 mm horizontally and 0.74 mm vertically. The statistics comparing the two types of images with the Wilcoxon test for paired samples showed no significant difference.Conclusion:When a CT scan is necessary for assessment of complex craniofacial dysplasias, an orthodontic-specific diagnosis is possible without having to resort to conventional X-rays of the skull. The data from this study demonstrate that it is possible to construct a cephalogram from CT data, which can be analyzed in the same way as a conventional cephalogram provided that the CTs field of view is large enough.ZusammenfassungFragestellung:Ziel der Studie war es zu untersuchen, ob auf CT-basierten Fernröntgenseitenbildern (FRS) knöcherne, dentale und Weichteilreferenzpunkte mit der gleichen Präzision gesetzt werden können wie auf herkömmlichen digitalen FRS.Material und Methodik:Retrospektiv wurden neun Patienten ohne kraniofaziale Fehlbildung (2 weiblich, 7 männlich, 12,8–32,3 Jahre) ausgewählt, bei welchen innerhalb von maximal 6,5 Monaten sowohl ein CT als auch ein digitales FRS erstellt wurden. Die FRS wurden mit dem ORTHOPHOS Plus DS Ceph® erstellt und die CT-Untersuchung mit dem SOMATOM Sensation® 16 bzw. 64 durchgeführt. Die CT-basierten FRS wurden im Programm VoXim® 4.3 auf Basis der axialen Rekonstruktionen im Knochenfenster generiert. Die Analyse aller FRS-Bilder erfolgte mit der Software Onyx Ceph® 2.7 und wurde von zwei Kieferorthopäden und fünf Weiterbildungsassistenten durchgeführt. Jedes Bild wurde pro Untersucher fünfmal an verschiedenen Tagen ausgewertet. Die statistische Analyse erfolgte mit SPSS 13.0 und 14.0. Dabei wurde die Abweichung vom jeweiligen Mittelwert untersucht.Ergebnisse:In der deskriptiven Statistik zeigte sich gemittelt über alle 61 betrachteten Punkte im konventionellen FRS in der Horizontalen ein mittlerer Quartilabstand von durchschnittlich 0,62 mm und in der Vertikalen von 0,67 mm. Demgegenüber betrugen die Werte im CT-basierten FRS in der Horizontalen 0,64 mm und in der Vertikalen 0,74 mm. Beim Vergleich der Ergebnisse zwischen beiden Bildtypen mit dem Wilcoxon-Test für verbundene Stichproben ergab sich für alle 61 betrachteten Punkte kein signifikanter Unterschied.Schlussfolgerung:Für die Diagnostik komplexer Fehlentwicklungen in der Kieferorthopädie, bei der eine CT-Untersuchung des Schädels notwendig ist, kann unter Zugrundelegung der vorliegenden Daten zur Reduktion der Gesamtstrahlenbelastung auf ein konventionelles FRS verzichtet werden, da sich ein FRS-Bild aus dem vorhandenen CT-Datensatz bei vergleichbarer Auswertbarkeit erstellen lässt, sofern ein ausreichend großes Volumen aufgenommen wurde.

Auswirkungen der Skoliose auf den Gesichtsschädel

ZusammenfassungBei 101 Skoliosepatienten wurden die Auswirkungen der Skoliose auf den Gesichtsschädel nachgeprüft. Es zeigte sich, daß etwa die Hälfte aller Skoliosepatienten auch Gesichtsskoliosen unterschiedlichen Schweregrades aufwiesen. Dies wird an den zahlenmäßig weit überwiegenden rechtskonvexen Skoliosen deutlich. Ein direkter statistisch sicherbarer Zusammenhang zwischen Wirbelsäulen- und Gesichtsskoliosen besteht bei schweren rechtskonvexen thorakalen Skoliosen.SummaryIn 101 patients with spinal scoliosis we measured the coincidence of scoliosis and deformities of the head. About 50 per cent of patients with spinal scoliosis show different degrees of scoliosis of the head. This can be proved in those cases of a scoliosis, which is convex to the right side. Patients with severe thoracal scoliosis have a correlation between scoliosis of the spinal column and head.RésuméChez 101 patients affectés de scoliose, on en a examiné les effets sur la face. Près de la moitié de tous les patients atteints de scoliose présentaient aussi à différents degrés de gravité des scolioses de la face. Celles-ci étaient plus fréquemment des scolioses convexes droites. Il existe une relation statistique nette entre la colonne vertébrale et la scoliose de la face dans les cas de graves scolioses convexes droites du thorax.

Vertical and Sagittal Growth in Patients with Unilateral and Bilateral Cleft Lip and Palate—A Retrospective Cephalometric Evaluation:

Objective: To investigate whether the craniofacial vertical and sagittal jaw relationship in patients with cleft lip and palate (CLP) differed from that of age-matched noncleft controls, before and after the pubertal growth spurt. Design: Retrospective observational study. Patients: The study group comprised 126 patients with CLP, subdivided according to gender and cleft type, and the control group comprised 53 age-matched skeletal class I patients. Methods: Angular and linear measurements were taken from prepubertal and postpubertal lateral cephalograms of all patients. Results: In patients with cleft lip and palate, the maxillary retrognathism became more remarkable with increasing age; whereas, the retrognathic position of the mandible became less pronounced as compared with controls. Reduced posterior midfacial height, a common prepubertal finding in patients with cleft lip and palate, was significant in postpubertal girls and young women with unilateral cleft lip and palate (p  =  .002). The total anterior facial height in male patients with bilateral cleft lip and palate was larger than in control patients (p  =  .002) after the pubertal growth spurt due to an increased anterior midfacial height. In male patients with unilateral cleft lip and palate, this finding was due to an increased anterior lower facial height (p < .001). Conclusions: Patients with cleft lip and palate treated according to a standardized treatment concept had adequate craniofacial jaw relationships after puberty. Despite a measured skeletal class I in both male and female patients with cleft lip and palate regardless of cleft type, there was a slight tendency toward a skeletal class III. Findings were similar for all groups of cleft lip and palate patients irrespective of the type of orthodontic treatment performed.

Periodontal Status and Oral Hygiene in Two Populations of Cleft Patients

Objective: To evaluate and compare the oral hygiene and periodontal status in children with unilateral and bilateral cleft lip and palate treated in Łódź, Poland, and Erlangen, Germany. Design: Oral health was assessed by the presence of dental plaque, pocket depth, clinical attachment levels, and pathologic teeth mobility. Subjects and Methods: Thirty-seven Polish and 63 German patients participated in this study. Results: Poor oral hygiene was found in 57% of all subjects. In Erlangen, 60% of patients had optimal oral hygiene, compared to 19% in Łódź. The highest scores for dental plaque were noted in both groups in the cleft region. Healthy periodontium was significantly more frequent among German patients, whereas gingival bleeding was significantly more frequent among Polish patients. Pocket depths greater than 6 mm occurred only in German subjects. No statistically significant difference was observed between the amount of tooth areas with gingival recessions and the country of origin. Periodontal pockets deeper than 3.5 mm occurred more frequently during active orthodontic treatment. Conclusions: The oral hygiene regimens in Germany and Poland were not comparable, as more plaque was found in the Polish than in the German population. Plaque accumulation seems not to be a key factor in causing periodontal destruction in the cleft area. Factors other than oral hygiene should be considered of major importance in relation to the development of gingival recession on teeth in cleft areas.

Influence of Early Hard Palate Closure in Unilateral and Bilateral Cleft Lip and Palate on Maxillary Transverse Growth During the First Four Years of Age

OBJECTIVE To evaluate and compare the effects of early primary closure of the hard palate on the anterior and posterior width of the maxillary arch in children with bilateral (BCLP) and unilateral (UCLP) cleft lip and palate during the first 4 years of life. DESIGN A retrospective, mixed-longitudinal study. SETTING Cleft Palate Center of the University of Erlangen-Nuremberg. SUBJECTS AND METHODS The present investigation analyzes longitudinally 42 children with UCLP and 8 children with BCLP between 1996 and 2000 with early simultaneous primary closure of lip and hard palate (4 to 5 months). Palatal arch width was measured on dental casts with a computer-controlled three-dimensional digitizing system, and their growth velocities were calculated from consecutive periods (mean follow-up 39 months). Differences in growth velocities were compared with those of 25 children with UCLP and 15 children with BCLP with delayed closure of hard palate (12 to 14 months). RESULTS AND CONCLUSIONS There was no significant difference in terms of anterior and posterior maxillary width between early and delayed closure of hard palate within the first 4 years of life.

Repeatability and reproducibility of landmarks—a three-dimensional computed tomography study

The aim of this study was to investigate the repeatability and reproducibility of the placement of anthropological cephalometric landmarks on three-dimensional computed tomography (3D CT) cranial reconstructions derived from volume data sets. In addition, the influence of the observers experience on the repeatability of landmark setting was also explored. Twenty patients without any craniofacial deformity (11 females and 9 males; age range 6.1-16 years) were selected retrospectively from CT volume data sets already available from 695 patients of Dental Clinic 3, Orthodontics of Erlangen University Hospital. The CT examination was performed with the SOMATOM Sensation64 (Siemens AG Medical Solutions, Erlangen, Germany). The program VoXim6.1 (IVS Solutions AG, Chemnitz, Germany) was used for 3D reconstruction of the volume data sets. A total of 28 landmarks were examined in the skeleton module of the program VoXim6.1. The randomly sorted data sets were analysed by two orthodontists and two postgraduate students. Each data set was analysed twice by each observer at an interval of 3 weeks. The analysis of variance regarding random effects was used to calculate the intraobserver and interobserver components of standard deviation (SD) of depiction of individual landmarks as measures of repeatability and reproducibility, respectively. Median intraserial SD and interserial SD of 0.46 mm (range: 0.14-2.00 mm) and 0.20 mm (range: 0.02-2.47 mm), respectively, were obtained depending on the landmark and plane. This study included systematic analysis of extreme values (outliers) in the assessment of the quality of measurements obtained. Descriptive statistics revealed qualitative differences in the depiction of different landmarks. The landmarks nasion and infradentale revealed a minor SD in all three spatial coordinates with the smallest SD for infradentale (SD = 0.18 mm) in the transverse plane. However, no systematic trend was identified with regard to the influence of the observers level of experience affecting the repeatability of landmark positioning. Thus, the repeatability and reproducibility of placements of landmarks with 3D CT were found to be acceptable for a majority of anatomical positions.