tooth germ. It appears as painless swelling, but it should be distinguished from cystic lesion or other benign tumor. Although odontogenic myxoma is benign, its behavior is known to be aggressive and infiltrative, so thorough curettage and enucleation is necessary. We report a case of odontogenic myxoma of the mandible observed in our clinic with good prognosis after enucleation was done.]]>
Curettage ; Mandible ; Myxoma ; Prognosis ; Tooth Germ

OBJECTIVETo determine the expression and possible function of CIC-5 during the rat tooth germ development.

METHODSIsolated total mRNA and protein from the rat tooth germs which were at different stages of development. RT-PCR and Western blot were used to investigate the mRNA and protein expression of the CIC-5 in the rat tooth germ.

RESULTSThe mRNA and protein of CIC-5 expressed in the late bell stage, but undetected inThe mRNA and protein of CIC-5 expressed in the late bell stage, but undetected in the early or middle bell stage.

CONCLUSIONThese results showed the spatial temporal distribution of expression of CIC-5 during the different stages of the rat tooth germ development and suggested that it might contribute to the rat tooth germ development.

Ameloblasts ; Animals ; Odontogenesis ; RNA, Messenger ; Rats ; Tooth Germ

OBJECTIVEThe Sonic hedgehog signalling peptide has been demonstrated to play important roles in the growth and patterning of the tooth development. This study aims on whether the antagonist beta-transduction repeat containing protein of Sonic hedgehog signal transduction expressed in tooth germs ameloblast and odontoblast or not.

METHODSThe mouse embryo heads of different developmental stages of E10.5, E13.5, E14.5, E16.5, E18.5 and P0, P3, P6 after birth were acquired fixed with 4% paraformaldehyde for 48 hours, embeded with Paraffin and examined using LsAB (labelled streptavidin-biotin) method to observe the beta-TrCP expression pattern in tooth germs, ameloblast and odontoblast.

RESULTSIt was demonstrated that beta-TrCP expressed in oral epithelium, tooth bud, mesenchymal cell cytoplasm of ameloblast and odontoblast of different stage of tooth development.

CONCLUSIONbeta-TrCP expressed from early stage to later stage of murine tooth development. And these findings provide the evidence of antagonist regulatory pathways for shh in teeth development.

Ameloblasts ; Animals ; Mice ; Odontoblasts ; Odontogenesis ; Signal Transduction ; Tooth Germ

tooth germs, and the fracture pattern different from that of adults are among those. In general, both surgical and non-surgical methods are considered as treatment protocols but the latter such as circumferential wiring with surgical plate would be a better choice when dealing with children of this type of trauma. This investigation was to estimate the fracture pattern of children in the northeastern area of Seoul, South Korea and compared the required results with literature reviews. The thirty-six child patients referred to the department of romaxillofacial surgery at Sanggyepaik hospital during last 12 years (from 1990 to 2002) were analyzed. This study shows the following results. The mandibular fracture was more prevalent among boys than girls. Falling was the most common cause of mandibular fracture in children aged 0 to 5 year. Symphysis and condyle were the most popular fractured sites in children. The circumferential wiring with surgical plate was the most provided treatment method.]]>
Adult ; Child ; Clinical Protocols ; Female ; Humans ; Korea ; Mandible ; Mandibular Fractures ; Seoul ; Tooth ; Tooth Germ

Tooth germ injury can lead to abnormal tooth development and even tooth loss, affecting various aspects of the stomatognathic system including form, function, and appearance. However, the research about tooth germ injury model on cellular and molecule mechanism of tooth germ repair is still very limited. Therefore, it is of great importance for the prevention and treatment of tooth germ injury to study the important mechanism of tooth germ repair by a tooth germ injury model. Here, we constructed a Tg(dlx2b:Dendra2-NTR) transgenic line that labeled tooth germ specifically. Taking advantage of the NTR/Mtz system, the dlx2b⁺ tooth germ cells were depleted by Mtz effectively. The process of tooth germ repair was evaluated by antibody staining, in situ hybridization, EdU staining and alizarin red staining. The severely injured tooth germ was repaired in several days after Mtz treatment was stopped. In the early stage of tooth germ repair, the expression of phosphorylated 4E-BP1 was increased, indicating that mTORC1 is activated. Inhibition of mTORC1 signaling in vitro or knockdown of mTORC1 signaling in vivo could inhibit the repair of injured tooth germ. Normally, mouse incisors were repaired after damage, but inhibition/promotion of mTORC1 signaling inhibited/promoted this repair progress. Overall, we are the first to construct a stable and repeatable repair model of severe tooth germ injury, and our results reveal that mTORC1 signaling plays a crucial role during tooth germ repair, providing a potential target for clinical treatment of tooth germ injury.
Animals ; Mice ; Mechanistic Target of Rapamycin Complex 1/pharmacology* ; Signal Transduction ; Tooth/metabolism* ; Tooth Germ/metabolism* ; Odontogenesis

OBJECTIVETo study role of dental follicle in tooth root development.

METHODSSixteen mandibular first molar dental germs from eight five-day postnatal Balb/c mice were divided into two groups randomly. Dental follicle of germs in one group was undetached and that of another group was removed. Subsequently, each of the germs was separately transplanted to back-muscles of adult nude mice. At seventh and fourteenth day after transplanting, the germs were collected, fixed, demineralized, dehydrated, and embedded in wax in sequence. Serial sections of 5 microm thick were made following the routine methods, stained with haematoxylin-eosin dying solution, and observed under a light microscope.

RESULTSAll implantations were located in the back-muscles with abundant capillary vasculature. Under microscope, although all tooth germs could further develop after grafting, tooth germs without dental follicle developed slowly with small size and low calcification compared to those with dental follicle. Although position of Hertwig's epithelial root sheath of all germs seemed no changing, roots of the group with dental follicle could further develop and the roots develop toward the apical direction; this tendency couldn't be seen in the germs of another group. Inflammatory cells could be seen in and out of the pulp cavity of the two groups at 7th day after grafting, while no obvious inflammatory cell was observed at 14th day after grafting.

CONCLUSIONDental follicle play an important role in tooth root development. It probably can lead tooth root to develop in normal direction.

Animals ; Dental Pulp Cavity ; Dental Sac ; Enamel Organ ; Mice ; Mice, Nude ; Molar ; Odontogenesis ; Tooth ; Tooth Germ ; Tooth Root

Differentiation and activation of osteoclasts are crucial in bone resorption. RANKL released from osteoblasts, also known as ODF, and proteins such as OPG/OCIF, decoy receptor of RANKL for inhibition of osteoclast formation play an important role. Teeth exhibit various movement patterns in mandible before eruption, inevitably accompaning peripheral bone resorption. Therefore, it is very meaningful to study osteoclasts differentiation and activation-related various factors near developing teeth for prediction of tooth movement patterns and understanding of mechanism of pre-and post-eruptive movement. This study examined distribution of RANKL and OPG in the mandible of postnatal 1~24 day rats containing developing teeth using immunohistochemical methods. After birth, the mandibular pre-eruptive first and second molars showed tooth germ morphology from bell stage to crown stage. In postnatal day 17, the mandibular first molar crown was completed and continuous eruption was in process along with root formation. On the twenty fourth day after birth, it was exposed to the oral cavity. RANKL exhibited strong positive immunohistochemical reactions in dental follicles and stromal cells around the mandibular first molar. On the third day after birth, strong positive reaction to RANKL was observed in the alvelolar bone above the mandibular first molar along with appearance of numerous osteoclasts. The reactivity was slightly attenuated on the seventh day and increased again on the tenth day after birth. The positive immunoreactivities were found not only in alveolar bone above the developing first molar, but also in stromal cells of the cervical area in contact with HERS. The alveolar bone below developing roots was also strongly stained. OPG displayed a similar patterns in the RANKL expression and locations of posively reacting cells, but relatively weakly stained on the third and tenth day after birth, when numerous osteoclasts made their appearnace. Above results suggest that RANKL and OPG have a close relation to the teeth movement in mandible such as eruption during teeth developing process. They also imply that RANKL and OPG play an important role in osteoclasts formation after synthesized in dental follicular cells and alveolar stromal cells.
Animals ; Bone Resorption ; Crowns ; Dental Sac ; Mandible ; Molar ; Mouth ; Osteoblasts ; Osteoclasts ; Parturition ; Rats* ; Stromal Cells ; Tooth Germ ; Tooth Movement ; Tooth*

Tooth replacement is a common trait to most vertebrates, including mammals. Mammals, however, have lost the capacity for continuous tooth renewal seen in most other vertebrates, and typically have only 1-2 generations of teeth. Here, we review the mechanisms of tooth replacement in reptiles and mammals, and discuss in detail the current and historical theories on control of timing and pattern of tooth replacement and development.
Animals ; Biology ; Humans ; Mammals ; physiology ; Odontogenesis ; genetics ; physiology ; Reptiles ; physiology ; Tooth ; growth & development ; Tooth Germ ; embryology ; Tooth, Deciduous ; growth & development

Alveolar bone grows with development of tooth germs and roots; bone deposition occurs with tooth eruption. Bone tion and deposition, and when the balance between them is disrupted, decrease in components undergoes processes ofre=sorpda lern alveolar bone height or excessive bone deposition result. It has been known that repositioning of teeth through orthodontic treatment can cause alveolar bone resorption which result in decreased alveolar bone height, and there have been many studies to evaluate such effects. X-ray films that could be rephated and standardized were chosen in clinical studies, and among them, bitewmg films men used for objective evaluation of changes in alveolar bone level. Twenty subjects, 10 to 13-year- old (average 10) children with C1 I molar key, healthy oral condition, no congenital missing, no periodontal 4domnttal disease, and pre-and bitewing films, were randomly selected for comparison of alveolar bone heigh. Amounts of tooth and changes in alveolar bone heights were analyzed. The following results were obtained: 1. Amount of tooth mmaneit in canine, premolar, and molar regions, changes in tooth axis, and changes in alveolar bone heights were measured, and the mean and median values were obtained. 2. When pre-and post-orthodontic alveolar bone levels were compared, larger changes were noticed in maxilla than mandible. 3. When mesio-distally compared, larger changes were observed in the distal sides of 3D3 and 4M3, mesial sides of 4M3 and 4D3, distal sides of 4D3 and 5M3, mesial sides of 5M3 and 5D3, and distal sides of 5D3 and 6M3. 4. When the amounts of tooth movements(TX, Mand changes in tooth axis(A) were compared, 34TX, 34TY, 34A of both sides in maxilla were greater, and changes in alveolar bone level were greater than any other region.
Axis, Cervical Vertebra ; Bicuspid ; Bone Resorption ; Child ; Humans ; Male ; Mandible ; Maxilla ; Molar ; Tooth ; Tooth Eruption ; Tooth Germ ; X-Ray Film

Devitalization has been widely used in the root canal therapy of primary and permanent teeth in China more than ten years ago. With the development of local anesthetic drugs and injection technologies, this treatment method with high potential risks has been gradually abandoned. However, a questionnaire survey targeted all the participants at the 2018 China Pediatric Dentistry Conference showed that the devitalizer utilization proportion was still as high as 38.1% (383/1 005), even though the ratio was much lower than 75.5% (105/139) in 2003. These doctors had pay more attention to tissue burn caused by devitalizer marginal leakage or direct leakage, and know how to identify and handle with devitalizer burn. Devitalizers were usually made of arsenic trioxide, metal arsenic or paraformaldehyde, which have cytotoxicity, allergenicity, mutagenicity, carcinogenicity, and teratogenic effects on animals. Marginal leakage of devitalizers have high risks of causing soft and hard tissue necrosis. Most of the dentists have an understanding of the potential damages of arsenic containing devitalizers, so they will choose parafor maldehyde with relatively less toxicity. Paraformaldehyde has a certain self limitation, and there are few cases reported, so some dentists lack of vigilance. Paraformaldehyde can also causes tissue necrosis if leakage happens, and the treatment methods are similar to that of arsenic containing devitalizers. When handling with devitalizers burn, the necrosed soft and hard tissue, for example gingiva, alveolar bone or teeth that cannot keep, must be completely removed until fresh blood appears, then rinse with large amount of saline and seal with iodoform gauze. This paper described two cases of devitalizer burn during the root canal treatment of primary molars, both of the doctors failed to identify the devitalizer burn symptoms in the early stage, thus didn't do proper treatments immediately after burning. Resulting in the necrosis of large area of gingiva and alveolar bone, loss of primary molars and permanent tooth germs 1-2 months after devitalizer burn. This paper reported these two cases in detail in order to warn dentists the high risks of using any kind of devitalizers, help them learn how to identify and treat devitalizer burn, and remind them to stop using devitalizers as soon as possible.
Arsenic/toxicity* ; China ; Dental Pulp Devitalization ; Humans ; Necrosis ; Root Canal Therapy ; Tooth Germ ; Tooth Loss/chemically induced* ; Tooth, Deciduous