Development of the primary and secondary jaw joints in the mouse.

This study assesses the morphogenesis of the primary and secondary jaw joints. A collection of 11 murine heads, ranging from prenatal stage E13.5 to postnatal stage P10, were prepared as histological serial sections (thickness 8-10 µm) and stained conventionally in order to examine them with light microscopy.

Structural, mechanical and chemical evaluation of molar-incisor hypomineralization-affected enamel: A systematic review.

Objectives: To systematically assess and contrast reported differences in microstructure, mineral density, mechanical and chemical properties between molar-incisor-hypomineralization-affected (MIH) enamel and unaffected enamel.

Methods: Studies on extracted human teeth, clinically diagnosed with MIH, reporting on the microstructure, mechanical properties or the chemical composition and comparing them to unaffected enamel were reviewed. Electronic databases (PubMed, Embase and Google Scholar) were screened; hand searches and cross-referencing were also performed.

Chondral ossification centers next to dental primordia in the human mandible: A study of the prenatal development ranging between 68 to 270mm CRL.

The human mandible is said to arise from desmal ossification, which, however, is not true for the entire body of the mandible: Meckel's cartilage itself is prone to ossification, at least its anterior part in the canine and incisor region. Also, within the coronoid and in the condylar processes there are cartilaginous cores, which eventually undergo ossification. Furthermore, there are a number of additional single cartilaginous islets arising in fetuses of 95mm CRL and more.

The remodeling pattern of human mandibular alveolar bone during prenatal formation from 19 to 270mm CRL.

The underlying mechanisms of human bone morphogenesis leading to a topologically specific shape remain unknown, despite increasing knowledge of the basic molecular aspects of bone formation and its regulation. The formation of the alveolar bone, which houses the dental primordia, and later the dental roots, may serve as a model to approach general questions of bone formation. Twenty-five heads of human embryos and fetuses (Radlanski-Collection, Berlin) ranging from 19mm to 270mm (crown-rump-length) CRL were prepared as histological serial sections.

Osteogenic Profile of Mesenchymal Cell Populations Contributing to Alveolar Bone Formation.

Teeth develop within the surrounding periodontal tissues, involving the alveolar bone, periodontal ligament and cementum. The alveolar bone originates through the process of intramembranous ossification involving mesenchymal cells from the tooth germ. As most available data are related to endochondral ossification, we examined the molecular background of alveolar bone development.

Morphogenesis of the compartmentalizing bone around the molar primordia in the mouse mandible during dental developmental stages between lamina, bell-stage, and root formation (E13-P20).

Despite increasing knowledge of the basic molecular aspects of bone formation and its regulation, the mechanisms of bone morphogenesis leading to a topologically specific shape remain unknown. The formation of the alveolar bone, which houses the dental primordia and later, the dental roots, may serve as a model to understand the formation of bone form in general. Thirty-eight heads of mice (C57 Bl/6J) ranging from stages E13-P20 were used to prepare histological serial sections.

Effect of methotrexate upon antigen-induced arthritis of the rabbit temporomandibular joint.

Background: Juvenile idiopathic arthritis (JIA) of the temporomandibular joint (TMJ) can cause severe growth disturbances of the craniomandibular system. Antigen-induced arthritis (AIA) of the rabbit TMJ is simulating the inflammatory process of the TMJ in JIA. The aim of this study was to investigate the effect of a systemic administration of methotrexate (MTX) on AIA in rabbits by means of three different histological staining methods.

Fluorosed mouse ameloblasts have increased SATB1 retention and Gαq activity.

Dental fluorosis is characterized by subsurface hypomineralization and increased porosity of enamel, associated with a delay in the removal of enamel matrix proteins. To investigate the effects of fluoride on ameloblasts, A/J mice were given 50 ppm sodium fluoride in drinking water for four weeks, resulting serum fluoride levels of 4.5 µM, a four-fold increase over control mice with no fluoride added to drinking water.

Distribution of BMP6 in the alveolar bone during mouse mandibular molar eruption.

Eruption requires synchrony of the tooth with the surrounding tissues, particularly the bone. One important step during eruption is remodelling of the alveolar bone at the base of the tooth and along the roots. Expression of BMP6 was reported to be increased in the basal half of the dental follicle prior to eruption and inhibition of BMP6 affected bone formation at the base of the alveolar crypt.

Morphogenesis and bone integration of the mouse mandibular third molar.

The mouse third molar (M3) develops postnatally and is thus a unique model for studying the integration of a non-mineralized tooth with mineralized bone. This study assessed the morphogenesis of the mouse M3, related to the alveolar bone, comparing M3 development with that of the first molar (M1), the most common model in odontogenesis. The mandibular M3 was evaluated from initiation to eruption by morphology and by assessing patterns of proliferation, apoptosis, osteoclast distribution, and gene expression.

Sexual dimorphism in teeth? Clinical relevance.

Many morphometric studies show a sexual dimorphism in human teeth. We wanted to know whether it is possible to determine the sex of an individual if only the anterior teeth are visible. Fifty intraoral photographs showing the front tooth region of female and male individuals (age: from 7 to 75 years) were randomly arranged in actual size on a questionnaire.

Tooth-bone morphogenesis during postnatal stages of mouse first molar development.

The first mouse molar (M1) is the most common model for odontogenesis, with research particularly focused on prenatal development. However, the functional dentition forms postnatally, when the histogenesis and morphogenesis of the tooth is completed, the roots form and the tooth physically anchors into the jaw. In this work, M1 was studied from birth to eruption, assessing morphogenesis, proliferation and apoptosis, and correlating these with remodeling of the surrounding bony tissue.

Interdental spacing and orthodontic treatment in competitive athletes: clues to doping with growth hormones?

Unlabelled: The aim of this report is to examine clues of a suspected link between the artificial ingestion of human growth hormone (rh- GH) and resulting interdental spaces in adult athletes. We conducted an electronic search in the German-language versions of the search engines Google and Google Scholar as well as in the database PubMed. While no explicit articles could be identified in PubMed, the search in Google and Google Scholar produced 1370 and 6 hits, respectively.

An atlas of prenatal development of the human orofacial region.

There are several atlases available showing prenatal human development. However, none is focused on prenatal orofacial development during maxillary and mandibular bone formation. These events, together with dental development and formation of the temporomandibular joint, take place during several fetal stages.

Ameloblast differentiation in the human developing tooth: effects of extracellular matrices.

Tooth enamel is formed by epithelially-derived cells called ameloblasts, while the pulp dentin complex is formed by the dental mesenchyme. These tissues differentiate with reciprocal signaling interactions to form a mature tooth. In this study we have characterized ameloblast differentiation in human developing incisors, and have further investigated the role of extracellular matrix proteins on ameloblast differentiation.

[Genes, forces and forms: mechanical aspects of prenatal craniofacial development].

Current knowledge of molecular signaling during craniofacial development is advancing rapidly. We know that cells can respond to mechanical stimuli by biochemical signaling. Thus, the link between mechanical stimuli and gene expression has become a new and important area of the morphological sciences.

New carbide finishing burs to reduce polishing efforts of light-cured restorations.

Objective: To compare, under laboratory conditions, the efficacy of different polishing systems for various light-curing restorative materials.

Method And Materials: Class 5 cavities were prepared in 65 human teeth and filled with 5 different light-curing restorative materials. To increase the number of samples, an extra 585 Class 5 cavities were made in resin disks and filled with the 5 different restorative materials.

Insular dentin formation pattern in human odontogenesis in relation to the scalloped dentino-enamel junction.

This study is a first report on the modality of early dentin formation in respect to the scalloped pattern of the dentino-enamel junction (DEJ). We applied scanning electron microscopy (SEM), transmission electron microscopy (TEM), histological serial sections, and three-dimensional (3D) reconstructions. TEM and SEM showed scallops and secondary scallops on the DEJ of deciduous dental primordia and on deciduous teeth with the enamel cap removed.

Developmental movements of the inner enamel epithelium as derived from micromorphological features.

It was the purpose of this article to analyze the (micro) morphological structure of enamel at different stages of development in order to deduce movement patterns of ameloblasts during formation of the human dental primordium. Developing enamel and overlying ameloblasts were dried and fractured for scanning electron microscopy (SEM) and sectioned for transmission electron microscopy (TEM). Specimens of human permanent enamel were either fractured and/or ground and etched to visualize the enamel rods.

Genes, forces, and forms: mechanical aspects of prenatal craniofacial development.

Current knowledge of molecular signaling during craniofacial development is advancing rapidly. We know that cells can respond to mechanical stimuli by biochemical signaling. Thus, the link between mechanical stimuli and gene expression has become a new and important area of the morphological sciences.

Growth factor expression following clinical mandibular distraction osteogenesis in humans and its comparison with existing animal studies.

Aim: Lengthening the mandible by distraction osteogenesis (DO) is nowadays a well recognized technique in maxillofacial surgery. In this study growth factor expression profiles were examined in biopsies taken from six patients undergoing mandibular DO and compared with findings from a sheep model for mandibular DO.

Study Design: In all patients (and sheep), the ascending ramus was distracted 10-15 mm at a rate of 1mm/day using an intraoral device.

The effect of surface chemistry modification of titanium alloy on signalling pathways in human osteoblasts.

Establishing and maintaining mature bone at the bone-device interface is critical to the long-term success of prosthesis. Poor cell adhesion to orthopaedic and dental implants results in implant failure. Considerable effort has been devoted to alter the surface characteristics of these biomaterials in order to improve the initial interlocking of the device and skeleton.

Explainable and critical periods during human dental morphogenesis and their control.

Objective: To what extent is the current knowledge about regulatory and patterning processes gained from research on animal models (predominantly mouse) applicable to describe certain aspect of human prenatal dental development?

Methods: 3D-reconstructions were produced from serial sections of human dental primordia (Radlanski collection, Berlin) and scanning electron microscopic visualisation techniques were applied.

Results And Conclusion: There are several examples, where present knowledge of regulatory processes allows the understanding of changes in outline and form. However, many other examples show that much more complex regulatory mechanisms should be expected to explain the details of human prenatal dental development.

Development of multinuclear giant cells during the degradation of Bioglass particles in rabbits.

Bioglass particles of the compositions 45s5, 52s, and 55s were implanted in the distal femoral epiphysis of rabbits. Animals were sacrificed at 7, 28, and 84 days postoperatively and specimens investigated using electron microscopy and electron dispersive X-ray analysis. The intention was to correlate the finding of different types of multinuclear giant cells (MNGC) in the center of the implantation bed with earlier hypothesized accumulated particle eluates and changed particle compositions.

Stability of the bonded lingual wire retainer-a study of the initial bond strength.

Bonded lingual retainers (individually adjusted multistranded wires with one bond site per tooth) are used extensively to maintain the orthodontic treatment result. Failure or loss often leads to a relapse. The bond strength of bonded lingual retainers has not yet been studied in respect of the loads that can be withstood by them through deflection of the interdental archwire region.