Christopher J. Lux

Dental Arch Widths and Mandibular-Maxillary Base Widths in Class II Malocclusions Between Early Mixed and Permanent Dentitions

The aim of the study was to analyze the transverse morphology and development of the dental arches and skeletal mandibular-maxillary bases in untreated Class II malocclusions. Using the records of the Belfast Growth Study, a Class II division 1 group (II/1) and a Class II division 2 group (II/2) were compared with a Class I group and a control group with good occlusion. On posteroanterior cephalograms, maxillary skeletal base width and bigonial and biantegonial widths were determined at two-year intervals between seven and 15 years. Maxillary and mandibular intermolar widths were measured on the associated study casts. As a result, maxillary skeletal base widths were smallest in the Class II/1 subjects. No statistically significant differences were found among the groups for the skeletal mandibular widths. With respect to the development of the dental arches, maxillary intermolar widths were smaller in the Class II/1 group than in the Class I and the good-occlusion groups. These group differences were present for the total period of observation, ie, seven to 15 years, and statistically significant at most ages. When the relative difference between the maxillary and the mandibular intermolar widths was examined, the Class II/1 cases were found to have the largest average difference (about -2.5 mm for boys and -1.5 mm for girls), indicating a relatively narrow maxillary arch. Less pronounced molar differences were found in the Class II/2 group. In the Class II/1 subjects the deviations in molar differences observed at 15 years of age were established already at 7 years of age and maintained during 7 and 15 years of age.

Indications for digital volume tomography in orthodontics.

Disturbances in tooth eruption and tooth impactions make great demands on radiographic diagnostics. There is often need for radiographic images in various projections to assess the exact position of unerupted and impacted teeth. Digital volume tomography (DVT) is a method for localizing hard tissue structures such as bone and teeth on various planes. Moreover, it makes a three-dimensional image of the teeth, jaws and the viscerocranium possible.From an orthodontic point of view, digital volume tomography is indicated to detect impacted and ectopic teeth and to demonstrate the amount of bone available for orthodontic tooth movement. In patients with cleft lip and palate, DVT can be used to visualize the size of the alveolar cleft and to evaluate the position and development of multiple teeth, as these patients often suffer from disturbances in tooth eruption.ZusammenfassungIm Rahmen von Zahndurchbruchstörungen und Zahnverlagerungen werden in der Kieferorthopädie hohe Anforderungen an die Röntgendiagnostik gestellt, wobei häufig Aufnahmen in verschiedenen Ebenen notwendig werden, um die genaue Lage von retinierten und verlagerten Zähnen beurteilen zu können. Die digitale Volumentomographie (DVT) stellt hierbei ein Verfahren dar, das die Lokalisation von Hartgewebsstrukturen wie Knochen und Zähnen in beliebigen Ebenen zulässt. Darüber hinaus ist eine dreidimensionale Darstellung der Zähne, der Kiefer und des gesamten Gesichtsschädels möglich.Aus kieferorthopädischer Sicht umfasst das Indikationsspektrum der digitalen Volumentomographie insbesondere die Lokalisation impaktierter und verlagerter Zähne sowie die Darstellung des Knochenangebots im Hinblick auf die Durchführung kieferorthopädischer Bewegungen einzelner Zähne und Zahngruppen. Deshalb kann die DVT gerade auch bei Patienten mit Lippen-Kiefer-Gaumen-Spalten Anwendung finden, um das Ausmaß der Kieferspalte zu visualisieren und um Lage und Anlage einzelner Zähne zu beurteilen, da diese Patienten besonders häufig von Zahndurchbruchstörungen betroffen sind.

Occlusal status and prevalence of occlusal malocclusion traits among 9-year-old schoolchildren

The aim of this study was to provide detailed information concerning clinically relevant occlusal traits and the prevalence of occlusal anomalies in an orthodontically relevant period of dental development. Four hundred and ninety-four German schoolchildren (237 males and 257 females), median age 9 years, were orthodontically examined. Overjet and overbite were measured to the nearest 0.5 mm, and sagittal molar relationships were registered clinically to the nearest quarter unit. In addition, crossbites, scissor bites, and midline displacements were evaluated. Descriptive statistics was complemented by testing gender differences and differences between groups with Class I and Class II anomalies (Mann-Whitney U-test) as well as a statistical evaluation of differences between the three dental stages (Kruskal-Wallis test). Overjet exhibited an extreme range between -2 and 12 mm (median values 3-3.5 mm). An increased overjet was more prevalent than a reduced or reverse overjet, and a severely increased overjet greater than 6 mm was a common finding affecting around 5-10 per cent of the children. Similarly, overbite showed considerable variations of between -1 and 9 mm (medians 3-3.5 mm) and males exhibited a significantly larger overbite than females. In Class II malocclusion subjects, overbite was significantly enlarged (on average between 0.5 and 1 mm) when compared with those with a Class I malocclusion. Traumatic contact of the gingiva affected every 14th child. A Class II molar relationship of three-quarter units or more was a frequent finding affecting more than one child in five. In addition, at 9 years of age, 3 per cent of the children exhibited a Class III molar relationship of at least a half unit. The wide range of orthodontically relevant occlusal traits found in the present study underlines the need for orthodontic screening at 9 years of age (or earlier).

Effects of Early Activator Treatment in Patients with Class II Malocclusion Evaluated by Thin-Plate Spline Analysis

The aim of the present longitudinal cephalometric study was to evaluate the dentofacial shape changes induced by activator treatment between 9.5 and 11.5 years in male Class II patients. For a rigorous morphometric analysis, a thin-plate spline analysis was performed to assess and visualize dental and skeletal craniofacial changes. Twenty male patients with a skeletal Class II malrelationship and increased overjet who had been treated at the University of Heidelberg with a modified Andresen-Häupl-type activator were compared with a control group of 15 untreated male subjects of the Belfast Growth Study. The shape changes for each group were visualized on thin-plate splines with one spline comprising all 13 landmarks to show all the craniofacial shape changes, including skeletal and dento-alveolar reactions, and a second spline based on 7 landmarks to visualize only the skeletal changes. In the activator group, the grid deformation of the total spline pointed to a strong activator-induced reduction of the overjet that was caused both by a tipping of the incisors and by a moderation of sagittal discrepancies, particularly a slight advancement of the mandible. In contrast with this, in the control group, only slight localized shape changes could be detected. Both in the 7- and 13-landmark configurations, the shape changes between the groups differed significantly at P < .001. In the present study, the morphometric approach of thin-plate spline analysis turned out to be a useful morphometric supplement to conventional cephalometrics because the complex patterns of shape change could be suggestively visualized.

Compression-dependent Up-regulation of Ephrin-A2 in PDL Fibroblasts Attenuates Osteogenesis

Members of the ephrin/Eph family have recently been shown to be involved in the regulation of bone homeostasis in a murine model. The activation of the EphB4 receptor on osteoblasts by its ligand ephrin-B2 led to stimulation of osteoblastogenesis and therefore to bone formation. The activation of ephrin-A2-EphA2 signaling on osteoblasts inhibited the activation of osteoblast-specific gene expression, leading to bone resorption. Fibroblasts within the periodontal ligament periodontal ligament may be one of the first responders to orthodontic forces. Periodontal ligament fibroblasts (PDLF) are mechanoresponsive. Members of the ephrin/Eph family might link mechanical forces received by PDLF with the regulation of osteoblastogenesis on osteoblasts of the alveolar bone. To study whether ephrin-A2 is modulated upon compression, we subjected human primary PDLF to static compressive forces (30.3 g/cm2). Static compressive forces significantly induced the expression of ephrin-A2, while the expression of ephrin-B2 was significantly down-regulated. Moreover, osteoblasts of the alveolar bone stimulated with ephrin-A2 in vitro significantly suppressed their osteoblastogenic gene expression (RUNX2, ALPL) and decreased signs of osteoblastic differentiation, as demonstrated by a significantly reduced ALP activity. Together, these findings establish a role for this ligand/receptor system linking mechanical forces with the regulation of osteogenesis during orthodontic tooth movement.

Strain-dependent Up-regulation of Ephrin-B2 Protein in Periodontal Ligament Fibroblasts Contributes to Osteogenesis during Tooth Movement

Background: Regulation of bone remodeling during orthodontic tooth movement. Results: Tensile stress induces ephrin-B2 expression in PDL fibroblasts, and ephrin-B2-EphB4 interactions induce osteoblastogenesis in osteoblasts of the alveolar bone. Conclusion: Ephrin-B2-EphB4 signaling between PDLF and osteoblasts of the alveolar bone might contribute to bone remodeling during orthodontic tooth movement. Significance: Understanding the regulation of bone remodeling during orthodontic tooth movement is a prerequisite for pharmacological interventions. During orthodontic tooth movement, the application of adequate orthodontic forces allows teeth to be moved through the alveolar bone. These forces are transmitted through the periodontal ligaments (PDL) to the supporting alveolar bone and lead to deposition or resorption of bone, depending on whether the tissues are exposed to a tensile or compressive mechanical strain. Fibroblasts within the PDL (PDLF) are considered to be mechanoresponsive. The transduction mechanisms from mechanical loading of the PDLF to the initiation of bone remodeling are not clearly understood. Recently, members of the ephrin/Eph family have been shown to be involved in the regulation of bone homeostasis. For the first time, we demonstrate that PDLF exposed to tensile strain induce the expression of ephrin-B2 via a FAK-, Ras-, ERK1/2-, and SP1-dependent pathway. Osteoblasts of the alveolar bone stimulated with ephrin-B2 increased their osteoblastogenic gene expression and showed functional signs of osteoblastic differentiation. In a physiological setting, ephrin-B2-EphB4 signaling between PDLF and osteoblasts of the alveolar bone might contribute to osteogenesis at tension sites during orthodontic tooth movement.

Dental fear in children and adolescents: a comparison of forms of anxiety management practised by general and paediatric dentists

BACKGROUND. About 11% of children and adolescents suffer from dental fear. These young people run an increasing risk of undergoing more invasive treatments. AIM. We researched the management of dental anxiety in young patients by general and paediatric dentists as well as by trained and untrained dentists. DESIGN. Eight hundred dentists in Germany were interviewed via e-mail regarding their experience, treatment techniques, information material and complications during the treatment of fearful children. We also examined how difficult dentists judge the treatment of anxious children and how often they participate in continuing education courses. RESULTS. Paediatric dentists applied a greater spectrum of management techniques than general dentists. They used more often psychotherapeutic interventions and anxiety assessment questionnaires. Dentists who frequently attend in continuing education courses judged the treatment to be less difficult and also used psychotherapeutic interventions more often. CONCLUSIONS. German paediatric dentists and dentists who take continuing education courses utilise a broader range of techniques to manage dental anxiety. They may be eminently suited to treat children with severe forms of anxiety. Therefore, dentists who treat young patients should participate in education programmes so as to reduce both the anxiety of their patients and their own anxiety.

Sagittal and Vertical Growth of the Jaws in Class II, Division 1 and Class II, Division 2 Malocclusions during Prepubertal and Pubertal Development

Abstract.Aim:The aim of the present study was to evaluate the sagittal and vertical development of the jaws in Class II, Division 1 (II/1) and Class II, Division 2 (II/2) malocclusions. In addition, facial morphology was to be investigated in probands with these malocclusions.Probands and Methods:Maxillary and mandibular development was investigated with reference to lateral cephalograms of orthodontically untreated probands from the Belfast Growth Study at 7, 9, 11, 13 and 15 years of age. Moreover, development of facial width was assessed from the associated posteroanterior cephalograms, with radiographic magnifications being corrected in both the lateral and the posteroanterior cephalograms. A Class II/1 group (n = 17) and a Class II/2 group (n = 12) were compared with two control groups: a group with good occlusion (n = 18) and a Class I group (n = 37).Results and Conclusions:With respect to the sagittal position of the maxilla, no significant differences between the Class II groups and the controls were found. In the Class II/1 group, mandibular retrognathism was observed. The posterior position of the mandible present at 15 years of age had been present even at 7 years of age, and growth increments in the Class I and Class II/1 subjects were similar. In the Class II/2 groups no uniform pattern with respect to mandibular position was found. With respect to vertical development, a deficit in lower anterior facial height was found in the Class II/2 groups. In addition, between 7 and 15 years of age, growth increments in lower anterior facial height were significantly smaller in the Class II/2 subjects than in the controls. Furthermore, the Class II/2 groups displayed a more euryprosopic facial form on average. The cause of this characteristic facial morphology was the vertical deficit in lower anterior facial height. Overall, however, the broad variability and the small sample sizes, in particular of the Class II/2 groups, in the present study have to be seen as limitations.Zusammenfassung.Zielsetzung:Ziel der vorliegenden Arbeit war es, Unterschiede im Wachstumsverlauf bei Anomalien der Angle-Klassen II/1 und II/2 hinsichtlich der Sagittal- und Vertikalentwicklung der Kieferbasen aufzuzeigen. Zusätzlich wurde die Gesichtsmorphologie bei diesen beiden Anomaliegruppen untersucht.Probanden und Methode:Die Analyse der Kieferentwicklung erfolgte auf der Basis von Fernröntgenseitenbild-(FRS-)Aufnahmen kieferorthopädisch unbehandelter Probanden der Belfast Growth Study zu den Zeitpunkten 7, 9, 11, 13 und 15 Jahren. Zusätzlich wurde anhand von Schädel-PA-Aufnahmen die Entwicklung der Gesichtsbreite erfasst, wobei sowohl im FRS- als auch im PA-Bild die projektionsbedingten Vergrößerungen korrigiert wurden. Zwei Untersuchungsgruppen mit Anomalien der Angle-Klassen II/1 (n = 17) und II/2 (n = 12) wurden dazu zwei Kontrollgruppen gegenübergestellt: einer Klasse-I-Gruppe mit annähernd idealer Verzahnung (n = 18) und einer Klasse-I-Gruppe mit Anomalien (n = 37).Ergebnisse und Schlussfolgerungen:Der sagittale Einbau des Oberkiefers war in den Klasse-II-Gruppen und den Kontrollgruppen annähernd vergleichbar. Bei den Klasse-II/1-Probanden zeigte sich eine Retrognathie des Unterkiefers. Die mit 15 Jahren vorliegende posteriore Fehllage des Unterkiefers bestand bereits mit 7 Jahren, und die Wachstumszuwächse bei den Klasse-I- und -II/1-Probanden waren vergleichbar. Bei den Klasse-II/2-Anomalien ergab sich kein einheitliches Bild in Bezug auf eine Retrognathie des Unterkiefers. Im Hinblick auf die Vertikalentwicklung lag bei der Angle-Klasse II/2 ein Wachstumsdefizit im Bereich der unteren Gesichtshöhe (anterior) vor. Darüber hinaus waren zwischen dem 7. und 15. Lebensjahr bei Klasse-II/2-Probanden die Zuwächse der unteren Gesichtshöhe in beiden Geschlechtern signifikant kleiner als in den Kontrollgruppen. Zudem wiesen die Klasse-II/2-Probanden im Durchschnitt eine stärker euryprosope (breitgesichtigere) Gesichtsform auf. Ursächlich für diese charakteristische Gesichtsmorphologie war das vertikale Wachstumsdefizit im Bereich der unteren anterioren Gesichtshöhe. Insgesamt müssen jedoch in dieser Studie die große Variabilität und die kleinen Probandenzahlen, insbesondere bei den Klasse-II/2-Gruppen, als Einschränkungen genannt werden.

Human primary cementoblasts respond to combined IL-1β stimulation and compression with an impaired BSP and CEMP-1 expression.

Cementoblasts are cells that produce, secrete and direct the production of cementum. Resorption lacunae occur in over 90% of teeth at the compression side of the periodontal ligament and might result in an irreversible loss of the original root length. We isolated and cultivated human primary cementoblasts and investigated their expression pattern concerning markers of the osteoblastogenic differentiation (RUNX2, OCN, ALP, and BSP) and CEMP-1. Compared to osteoblasts, cementoblasts displayed an expression pattern comparable to osteoblasts in an early stage of osteoblastogenic differentiation. Next, the human primary cementoblasts were stimulated with IL-1β (1 and 10ng/ml) for 24 and 96h and subsequently subjected to compressive forces (30.3g/cm(2)) for 1 and 6h. Our in vitro data demonstrated that BSP and CEMP-1 expression significantly decreased when stimulation was accompanied by compression, while compression or stimulation alone led to increased levels of BSP and decreased levels of CEMP-1. We concluded that human primary cementoblasts subjected to compression and IL-1β stimulation impeded BSP and CEMP-1 expression, proteins that are associated with cementogenesis.

Applications for Direct Composite Restorations in Orthodontics

Abstract.Background and Aim:Besides prosthetic and indirect, laboratory-produced restorations, the focus of dental therapy is increasingly on restorative measures and direct restorations as minimally invasive treatment concepts. Thus, the use of direct composite restorations with modern restorative materials for the shaping and recontouring of teeth in combination with orthodontic treatment offers a diversified, extensive sphere of application. The aim of the study was to demonstrate applications for direct composite restorations with reference to selected cases.Material and Methods:The composites used were hybrid composites, which offer increased abrasion resistance and color stability and are applied incrementally. Special attention was paid to the shape, color and structure of the tooth.Case Reports:The case reports present patients in whom relatively narrow or peg-shaped teeth were built up with composite to correct various tooth size discrepancies or cuspids were recontoured by means of direct composite restorations following orthodontic space closure in cases with missing lateral incisors. Similarly, space closure was achieved using orthodontically repositioned lateral incisors recontoured to resemble central incisors after traumatic loss of upper central incisors. Finally, direct composite restorations were used for retention following completion of orthodontic treatment.Conclusions:Observations over recent years confirm the stability of composites in both form and color, as well as their ability to maintain gingival health. Our case reports demonstrate that, subject to a corresponding indication, recontouring single teeth using direct composite restorations can optimize orthodontic treatment results.Zusammenfassung.Hintergrund und Ziel:Neben Zahnersatz und indirekten Laborverfahren treten zunehmend zahnerhaltende Maßnahmen und direkte Restaurationen als minimalinvasive Behandlungskonzepte in den Vordergrund der zahnärztlichen Therapie. Daher bieten der Aufbau und die Umformung von Zähnen mit den heute zur Verfügung stehenden Kompositen im Sinne einer Formkorrektur in Kombination mit kieferorthopädischen Maßnahmen ein vielfältiges und umfangreiches Einsatzgebiet. Ziel dieser Arbeit ist es, die unterschiedlichen Einsatzmöglichkeiten moderner Komposite anhand ausgewählter Behandlungsbeispiele zu veranschaulichen.Material und Methodik:Verwendet wurden Hybridkomposite, die sich durch erhöhte Abrasionsfestigkeit und Farbbeständigkeit auszeichnen und in so genannter Mehrschichttechnik aufgetragen werden. Ästhetische Aspekte bezüglich Form, Farbe sowie Struktur des Zahnes wurden in besonderem Maß berücksichtigt.Fallbeispiele:Unsere Behandlungsbeispiele zeigen Patienten, bei denen bei Zahnbreitendiskrepanzen die relativ zu schmalen Zähne aufgebaut wurden oder bei denen nach kieferorthopädischem Lückenschluss bei Nichtanlage seitlicher Schneidezähne die Eckzähne der Form der fehlenden seitlichen Schneidezähne angeglichen wurden. Ebenso konnten nach traumatischem Verlust von Frontzähnen und anschließendem kieferorthopädischen Lückenschluss die eingeordneten Zähne entsprechend der Stellung im Zahnbogen mit Komposit umgestaltet werden. Schließlich wurden Komposite auch zur Stabilisierung von Zahnstellungen und von kieferorthopädischen Behandlungsergebnissen eingesetzt.Schlussfolgerungen:Mehrjährige Fallbeobachtungen bestätigen die Beständigkeit der Komposite in Form und Farbe sowie die Stabilität der parodontalen Situation. Unsere Behandlungsbeispiele zeigen, dass sich durch die Umgestaltung einzelner Zähne mit Kompositmaterialien das kieferorthopädische Behandlungsergebnis bei entsprechender Indikation optimieren lässt.