Craniofacial and Dental Defects in the Col1a1Jrt/+ Mouse Model of Osteogenesis Imperfecta.

Certain mutations in the COL1A1 and COL1A2 genes produce clinical symptoms of both osteogenesis imperfecta (OI) and Ehlers-Danlos syndrome (EDS) that include abnormal craniofacial growth, dental malocclusion, and dentinogenesis imperfecta. A mouse model (Col1a1(Jrt)/+) was recently developed that had a skeletal phenotype and other features consistent with moderate-to-severe OI and also with EDS. The craniofacial phenotype of 4- and 20-wk-old Col1a1(Jrt)/+ mice and wild-type littermates was assessed by micro-computed tomography (µCT) and morphometry. Teeth and the periodontal ligament compartment were analyzed by µCT, light microscopy/histomorphometry, and electron microscopy. Over time, at 20 wk, Col1a1(Jrt)/+ mice developed smaller heads, a shortened anterior cranial base, class III occlusion, and a mandibular side shift with shorter morphology in the masticatory region (maxilla and mandible). Col1a1(Jrt)/+ mice also had changes in the periodontal compartment and abnormalities in the dentin matrix and mineralization. These findings validate Col1a1(Jrt)/+ mice as a model for OI and EDS in humans.

The regulatory role of a disintegrin and metalloproteinase 28 on the biologic property of human periodontal ligament stem cells.

BACKGROUND: A disintegrin and metalloproteinase 28 (ADAM28) is considered to be the possible virulence gene for congenital hypoplasia of tooth root. Periodontal ligament stem cells (PDLSCs) are regarded as playing crucial roles in the developing process of the periodontium and are generally used in dental regenerative medicine. This study evaluates the influence of ADAM28 on the biologic property of human PDLSCs (HPDLSCs) and to postulate the possible mechanism of this influence. METHODS: HPDLSCs were acquired by immunomagnetic bead selection and identified by immunofluorescence detection. After ADAM28 eukaryotic plasmid and antisense oligodeoxynucleotides (AS-ODNs) were constructed and respectively transfected into HPDLSCs by a transfection reagent, the expression differences of ADAM28 among various groups were assessed by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting. The 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyl-2H-tetrazolium bromide and cell-cycle assays were used to test the proliferation activity of HPDLSCs. Annexin V-fluorescein isothiocyanate/propidium iodide analysis was performed to detect the apoptotic level. Cell differentiation was tested by measuring the alkaline phosphatase level. Immunocytochemistry and Western blotting were carried out to determine the effects of ADAM28 AS-ODNs on HPDLSCs expressing cementum attachment protein (CAP), osteopontin, and osteocalcin. RESULTS: The ADAM28 eukaryotic plasmid group showed the highest expression level in HPDLSCs, whereas the AS-ODN group displayed the lowest. Furthermore, the overexpression of ADAM28 enhanced the proliferation of HPDLSCs and inhibited the specific differentiation of HPDLSCs, whereas the inhibition of ADAM28 produced the opposite effects and induced apoptosis. ADAM28 AS-ODNs were able to significantly inhibit CAP expression, and ADAM28 had a positive correlation with CAP. CONCLUSION: Our findings demonstrated that ADAM28 was able to effectively manipulate the proliferation, apoptosis, and differentiation of HPDLSCs.

Modificações no periodonto de ratos diabéticos após a movimentação ortodôntica / Periodontal ligament changes after induced dental movement in diabetic rats

OBJETIVOS: o objetivo deste trabalho foi avaliar as modificações do ligamento periodontal de incisivos de ratos diabéticos submetidos a forças ortodônticas. MÉTODOS: vinte ratos machos Wistar (Rattus norvegicus) com 105 dias de idade foram empregados. Os ratos foram divididos em quatro grupos: C - animais normoglicêmicos não submetidos à movimentação dentária; CAO - animais normoglicêmicos submetidos à movimentação dentária; D - animais diabéticos não submetidos à movimentação dentária; DAO - animais diabéticos submetidos à movimentação dentária. Os animais permaneceram com o dispositivo de movimentação dentária por 5 dias. Foram avaliados o número de vasos sangüíneos e a espessura do ligamento periodontal nos terços cervical, médio e apical dos cortes histológicos. RESULTADOS E CONCLUSÕES: no lado de tensão, a movimentação dentária nos animais do grupo CAO resultou em um ligamento periodontal mais espesso (17,64 por cento no terço apical, 39,28 por cento no terço médio e 51,35 por cento na região cervical), quando comparado ao grupo C (p < 0,05 para os terços médio e cervical). No grupo DAO, o aumento da espessura do ligamento periodontal foi 50,55 por cento (terço apical), 48,14 por cento (terço médio) e 50 por cento (terço cervical) maior que nos animais do grupo D (p < 0,05). O número de vasos sanguíneos encontrados no ligamento periodontal não apresentou diferenças estatisticamente significantes quando todos os grupos foram comparados (p > 0,05). Ainda no lado de tensão, foram observadas lacunas de reabsorção nos animais dos grupos CAO, D e DAO. O lado de pressão não foi examinado nesta fase do estudo.

AIM: The aim of this study was to evaluate the periodontal ligament changes after induced dental movement of the upper incisor in diabetic rats. METHODS: Twenty Wistar rats (Rattus norvegicus) with 105 days of age were used. The rats were divided in four groups: C - normoglicemic animals not submitted to dental movement; CAO - normoglicemic animals submitted to dental movement; D - diabetic animals not submitted the dental movement; DAO - diabetic animals submitted to dental movement. The animals had remained with dental movement devices during 5 days. The number of sanguine vessels and the thickness of the periodontal ligament were evaluated at cervical, medium and apical histological cut regions. RESULTS AND CONCLUSION: At tension side, the dental movement in the animals of group CAO resulted in a thicker periodontal ligament (17.64 percent apical, 39.28 percent medium, 51.35 percent cervical) when compared to C group (p < 0.05 for medium and cervical area). Group DAO exhibited an increase of periodontal ligament thickness of 50.55 percent (apical), 48.14 percent (average) and 50 percent (cervical) when compared to group D (p < 0.05). The periodontal ligament sanguine vessels number did not differed significantly for all groups (p < 0.05). At tension side, bone reabsorption lacunae were observed in CAO, D and DAO groups. The pressure side was not examined in this study phase.

Immunocytochemical characterization of ectopic enamel deposits and cementicles in human teeth.

Despite the relative frequency and clinical relevance of radicular enamel deposits and cementicles, their etiology and nature are unknown. The purpose of the present study was therefore to evaluate the presence and distribution of mineralization-associated non-collagenous matrix proteins (NCPs) in various types of root-associated ectopic mineralizations. Human teeth were processed for embedding in epoxy or acrylic resins. Tissue sections were incubated with antibodies to amelogenins (AMEL), bone sialoprotein (BSP), and osteopontin (OPN). Radicular enamel deposits contained residual organic matrix that labeled for AMEL. In contrast, BSP and OPN were not detected in the residual enamel matrix, they were found in the cementum deposited on its surface as well as in collagen-free cementicle-like structures in the adjacent periodontal ligament. True cementicles consisted of a collagenous matrix intermixed with a non-collagenous ground substance. Labeling for BSP and OPN was mainly associated with the interfibrillar ground substance. No immunoreactivity for AMEL was detected in cementicles. These data indicate that ectopic enamel deposits on the root retain a high amount of AMEL, whereas cementicles contain BSP and OPN, two NCPs typically found in bone and cementum. These NCPs may, like in their normal tissue counterparts, play a role in the mineralization process.

trkA modulation of developing somatosensory neurons in oro-facial tissues: tooth pulp fibers are absent in trkA knockout mice.

To investigate the nerve growth factor requirement of developing oro-facial somatosensory afferents, we have studied the survival of sensory fibers subserving nociception, mechanoreception or proprioception in receptor tyrosine kinase (trkA) knockout mice using immunohistochemistry. trkA receptor null mutant mice lack nerve fibers in tooth pulp, including sympathetic fibers, and showed only sparse innervation of the periodontal ligament. Ruffini endings were formed definitively in the periodontal ligament of the trkA knockout mice, although calcitonin gene-related peptide- and substance P-immunoreactive fibers were reduced in number or had disappeared completely. trkA gene deletion had also no obvious effect on the formation of Meissner corpuscles in the palate. In the vibrissal follicle, however, some mechanoreceptive afferents were sensitive for trkA gene deletion, confirming a previous report [Fundin et al. (1997) Dev. Biol. 190, 94-116]. Moreover, calretinin-positive fibers innervating longitudinal lanceolate endings were completely lost in trkA knockout mice, as were the calretinin-containing parent cells in the trigeminal ganglion.These results indicate that trkA is indispensable for developing nociceptive neurons innervating oral tissues, but not for developing mechanoreceptive neurons innervating oral tissues (Ruffini endings and Meissner corpuscles), and that calretinin-containing, trkA dependent neurons in the trigeminal ganglion normally participate in mechanoreception through longitudinal lanceolate endings of the vibrissal follicle.

Presença do canal cavo-inter-radicular em molares superiores e inferiores / Presence of foramina in the furcation and pulp chambers of upper and lower molars

Este trabalho teve como objetivo detectar a presença do canal-inter-radicular, nas regiöes de soalho e furca de molares superiores e inferiores, através de três métodos: olho nu, lupa comum e microscópio eletrônico de varredura. Foram utilizados quinze molares superiores e quinze molares inferiores. Os resultados mostraram a presença do canal cavo-inter-radicular em 46,6 por cento dos molares inferiores e em 26,6 por cento dos molares superiores. O número de foraminas na furca foi superior ao encontrado no soalho das amostras, sendo estatisticamente significante (Z=3,22). A maior foramina detectada encontrava-se na furca de um molar inferior e a menor foramina foi encontrada no soalho de um molar inferior