A comparison of current Orthodontic Board examinations.

Five orthodontic clinical Board examinations were systematically compared. An attempt was made to critically evaluate the procedures, characteristics and requirements of these examinations. Many similarities were found and the differences found between Boards may be due to differences in socio-political goals of the professional orthodontic societies organizing the examinations. By setting a high standard of clinical treatment as a basic goal, all Boards aim to raise the overall quality of clinical performance.

European Board of Orthodontists: a professional challenge.

The background to the formation of the European Board is given and the necessary procedures for obtaining certification of the European Board of Orthodontists (EBO) are described. An example case report is included to give the reader an indication of the type of detail required for each and every case presented. Recommendations are given for prospective candidates who might consider attempting EBO certification in the future.

[Synthesis and evaluation of the clinical approach to growth]. / Synthèse et évaluation de l'approche clinique de la croissance.

A critical reflection based on literature is presented to the lectures given at the symposium "A clinical approach to growth" at the 73rd Réunion Scientifique of the Société Française d'Orthopédie Dento-Faciale in Deauville, France, on may 13th, 2000. Uncertainty is expressed about the long-term effects on the growth pattern after early surgery in children. It is apparent that conventional dentofacial orthopedics have a limited long-term effect on the growth pattern. Surgical as well as non-surgical (orthopedic) approaches are plagued by complications and relapse. The need for unbiased clinical research and standardized, complete documentation and analysis--also on how/why clinical decisions were taken--seems of utmost importance for a balanced future development of conventional and newly introduced techniques.

[Complications in the treatment of angle class II division 1 malocclusion]. / Complicaties bij behandeling van Angle Klasse II/1-afwijkingen.

OBJECTIVE: This article describes a retrospective inventory of various categories of complications which occurred in a sample consecutively treated patients with Class II division 1 malocclusion. DESIGN: Retrospective, descriptive study. METHODS: Treatment was performed with a headgear-activator and a edgewise appliance. All patients originate from one orthodontic specialist office and were between 10 and 14 years of age during treatment. From the group of 600 patients 100 (n = 100) were randomly selected for the study. A standard form was used for the inventory of the complications. The complications were divided into 5 categories: dental, skeletal, functional, psychosocial and multiple (two or more complications). RESULTS: In the group of 100 patients no complications were found in 48 patients (48%); 52 patients showed complications (52%). From these 52 patients 29 showed one complication, 19 had 2 complications, 4 showed 3 complications. In total 79 complications occurred divided as follows: dental complications 23 (29.1%); skeletal complications 19 (24.1%); functional complications 15 (19.0%); psychosocial complications 22 (27.8%). CONCLUSION: Complications occur very frequently in the treatment of Angle Class II division 1 malocclusions. These complications may occur in various combinations and may compromise the treatment result in a variable way.

[Orthodontic diagnosis and panoramic radiology of the dentition in childhood]. / Panorama-röntgendiagnostiek van het kindergebit.

Every dentist has to know the dentitional development well enough to be able to assess regularly this complicated process with its many normal variations and (topical) aberrations. If they become clinical problems, they require diagnosis, long-term supervision and interceptive and/or corrective treatment. In this article the advantages and disadvantages of panoramic radiology for the diagnosis of the dentitional development are described. A systematic method of interpretation of the panoramic X-rays is recommended.

Growth and growth pressure of mandibular condylar and some primary cartilages of the rat in vitro.

To compare the in vitro development of the secondary cartilage of the mandibular condyle with that of primary cartilages, several cartilaginous explants derived from 4-day-old rats were cultured in a serum-free culture system. The following cartilages were used: the mandibular condylar cartilage, the distal epiphyseal cartilage (including the growth plate) of the third metatarsal, a fragment of costal cartilage (including the osteochondral junction) of the fourth rib, the spheno-occipital synchondrosis and the chondroepiphysis of the femoral head. In addition, with a specially designed, in vitro pressure registration system, the maximal growth pressures for each of the explants, except the femoral head, were determined. The results show an independent growth potential for the primary cartilages of the epiphyseal and costal growth plates with a maximal growth pressure of 9.5 and 7.8 g/mm2, respectively. The primary cartilage of the spheno-occipital synchondrosis, on the other hand, although it possesses an independent growth potential, could exert a maximum growth pressure of only 1.5 g/mm2. The secondary cartilage of the mandibular condyle showed a limited intrinsic growth potential, as well as a low maximal growth pressure (2.6 g/mm2). If calculated per dividing and/or matrix synthesizing cell (cells mainly responsible for the cartilage growth), the cells of the condylar cartilage showed the least growth potency (0.08 mg/cell in comparison to 1.9, 1.5 and 0.3 for epiphyseal, costal, and synchondroseal cartilages, respectively.

Initial displacements and variations of eight human child skulls owing to high-pull headgear traction determined with laser holography.

In this study eight macerated, human child skulls (dental age approximately 9.5 years) were subjected to a standardized high-pull headgear traction system. Tensile forces from 0.5 to 3.5 N (1 N = 0.1 kgf) per side were produced to the maxillae. Displacements of skeletal components were determined at 22 indicator points per skull by means of laser holography. Coordinated displacements and variations in amount and direction were established in all skulls. The overall amount of displacements was primarily a characteristic of an individual skull, not of a particular displacement. On the average, the maxillae were displaced in a slightly downward and posterior direction almost parallel to the occlusal plane. No deformations of skeletal components were seen. Results indicated that initial displacements of the maxillae and other skeletal components are not in the same direction as the direction of applied forces.

Holographic and cephalometric study of the relationship between craniofacial morphology and the initial reactions to high-pull headgear traction.

Eight macerated human child skulls with a dental age of approximately 9.5 years (mixed dentition) were consecutively subjected to an experimental standardized high-pull headgear traction system attached to the maxilla at the first permanent molar area via an immovable acrylic resin splint covering all teeth. This system produced tensile forces from 0.5 to 3.5 N (1 N = 0.10 kg) per side. Laser holography was used to measure displacements in a three-dimensional coordinate system. Displacements varied in direction. In addition, conventional cephalometric analysis of standardized lateral roentgen cephalograms was performed. Displacements and cephalometric data were then compared. Results indicate that the direction of initial displacements of bones of the facial skeleton bears a definite relationship to the morphology of the individual skull. In skulls with high divergency values (large angles, sella-nasion-occlusal plane, sella-nasion-mandibular plane), displacements are in a backward and posterior downward direction; in skulls with a small sella-nasion-occlusal plane angle, backward displacements occur in a direction almost parallel to the occlusal plane.

Effect of compressive forces on phosphatase activity in mandibular condylar cartilage of the rat in vitro.

Intermittent and continuous compressive forces were applied to mandibular condylar cartilages from four days old rats during culture. The distribution and the relative activity of alkaline and acid phosphatase were determined after various periods in culture. The application of a continuous compressive force reduced the activity evenly of both phosphatases in all zones of the condylar cartilage. A small intermittent compressive force (0.5-1.0 g) induced an increase in the intra- and extracellular alkaline phosphatase activity in the entire hypertrophic zone. It is concluded that biomechanical forces can influence the onset of the mineralisation process in mandibular condylar cartilage.

Effects of compressive forces on proliferation and matrix synthesis in mandibular condylar cartilage of the rat in vitro.

The cartilage from 4-day-old rats were exposed to continuous and intermittent compressive forces. Proliferative activity and matrix synthesis in vitro were determined by measuring the incorporation of [3H]-thymidine, [35S]-sulphate and [3H]-proline by autoradiography and liquid-scintillation counting. The findings suggest that a continuously-applied force of approx. 0.5 g stimulated proliferation in the condylar cartilage but reduced the synthesis of the sulphated glycosaminoglycans and collagen. A stimulatory influence on the synthesis of these matrix components, on the other hand, was observed when the condylar cartilage was exposed to an intermittent force (0.7 Hz) of approx. 0.5-1.0 g; this intermittent force, however, reduced the proliferative activity. It appears that, at least in vitro, the basic growth processes in the condylar cartilage can be regulated by compressive forces.

An in-vitro system for studying the effect of variable compressive forces on the mandibular condylar cartilage of the rat.

An in-vitro system enabled variable range of continuous and intermittent compressive forces to be applied to the cartilage of 4-day-old rats under serum-free culture conditions. A continuous compressive force below 3 g did not affect the growth of the cartilage; when the force exceeded 3 g, growth ceased. Under an intermittent compressive force up to 8 g, growth continued, but at a lower rate; over 8 g, growth ceased. When growth-restricting compression was removed or reduced, growth was reactivated until a new balance was achieved. The normal architecture of the different zones was altered in the non-compressed in-vitro controls, but not in cultured cartilage during the application of these compressive forces.

Growth of the mandibular condylar cartilage of the rat in serum-free organ culture.

To evaluate the intrinsic capacity for growth, the mandibular condylar cartilage of 4-day-old rats was cultured in a serum-free, chemically-defined medium for 28 days and compared with the condylar cartilage cultured in a serum-supplemented medium and with the normal growth in vivo. Under the serum-free culture conditions, cell proliferation, differentiation into functional chondroblasts and matrix formation continued, but chondroclasia and osteogenesis were absent. This resulted, after 28 days of culture, in an enlarged condylar cartilage with altered proportions, a severe reduction of the prechondroblastic and the transitional zone and a considerable increase of the hypertrophic zone. It appears that the serum-free culture system is unfavourable for endochondral osteogenesis and lacks factors modulating the rate of proliferation, differentiation and maturation of the prechondroblasts. In the functional environment of the condyle, humoral or mechanical factors seem to exert this essential modulating influence on the condylar-cartilage growth.

The initial reaction of a macerated human skull caused by orthodontic cervical traction determined by laser metrology.

Tensile forces were applied to the maxilla of a macerated human skull in a backward direction 10 degrees below the occlusal plane. The skull was fixed to a heavy metal support at the occipital and parietal bones. These forces were applied near the first permanent molars via a rigid stainless steel bar, which was fitted to a cast-metal splint attached to the palatal surface and buccal region of the maxillary arch. Forces were increased step by step from 2.0 N (1N = 100 grams) to 7.25 N per side. Using a holographic configuration with two 5 mW HeNe lasers, double-exposure holograms were made from the frontal and from the left lateral sides. Fringe shifts in different points of the hologram were measured and the x, y, and z components of the displacement were calculated for eight points located on various bones of the skull. Viewed from the frontal, force application to the maxilla resulted in a downward and backward rotation. The zygomatic bone was also rotated downward and backward with a small rotation in a transverse direction. Other craniofacial structures were also affected. With a force of 7.25 N per side, a deformation of the temporal bones and zygomatic arches occurred.

The initial effects of orthopedic forces: a study of alterations in the craniofacial complex of a macerated human skull owing to high-pull headgear traction.

The initial reaction of components of the craniofacial skeleton of a macerated human skull was studied after high-pull headgear traction. The applied forces were increased step by step from 0.5 N to 3.25 N per side (1N = 100 grams). Laser holography was used for measuring displacements in three dimensions in seventeen indicator points on the skull. These points were located near sutures or on the outer surface of individual bones. The skull was observed from the right frontal and from the left lateral side. Results indicate that displacements range from 0 micrometer to 17.0 micrometers, depending on force magnitude and on the location of the observed point. Individual components of the craniofacial skeleton were mostly displaced in a horizontal backward direction when the skull was viewed from the frontal aspect. Various compression and shearing patterns were observed in the craniofacial sutures, apparently depending on their spatial locations and intersutural surface morphology.