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

In 1863,the term odontoma was introduced by Paul Broca which he described as a tumor formed by overgrowth of transitory or complete dental tissue.The World Health Organization classified them under mixed benign odontogenic tumors because of their origin from epithelial and mesenchymal cells exhibiting different structures of dental tissue (enamel,dentin,cementum and pulp).There are two distinct  types:  compound  and  complex.  Compound  odontoma  is composed of all odontogenic tissue in an orderly fashion resulting in many teeth-like structures but with no morphological resemblance to normal teeth whereas a complex odontoma appears as an irregular mass with no similarity even to rudimentary teeth.
The pathogenesis of odontomas has not been completely established although the most accepted etiology is related to trauma, infection, growth pressure and genetic mutations in one or more genes that cause disturbances in the mechanism controlling tooth development.
Patients with compound odontoma are often asymptomatic. It is usually detected on routine radiography upon examination of an unerrupted tooth.Odontomas can occur anywhere in the jaws and are usually found associated with or within the alveolar process.
However,the presence of an odontoma in the maxillary sinus is very rare.We present a female patient with a compound odontoma in the maxillary sinus initially managed as nasal vestibulitis with maxillary sinusitis.

Human ; Female ; Middle Aged ; Odontoma ; Dental Cementum ; Maxillary Sinusitis ; Maxillary Sinus ; Tooth ; Dental Pulp ; Dental Enamel ; Dentin ; Alveolar Process ; Mutation

dental papilla of the tooth germ. The tooth germ, sometimes called the tooth bud, is the primordial structure from which a tooth is formed. The tooth germ consists of the enamel organ, the dental papilla, and the dental follicle. The dental papilla lies below a cellular aggregation of the enamel organ. Mesenchymal cells within the dental papilla are responsible for formation of dentin and pulp of a tooth. Tooth germ disappears as a tooth is formed, but that of a third molar stays in the jawbone of a human until the age of 10 to 16, because third molars grow slowly. Impacted third molar tooth germs from young adults are sometimes extracted for orthodontic treatment. In the present study, we evaluated the osteogenic activity and mineralization of cultured human dental papilla-derived cells. Dental papillas were harvested from mandible during surgical extraction of lower impacted third molar from 3 patients aged 13-15 years. After passage 3, the dental papilladerived cells were trypsinized and subsequently suspended in the osteogenic induction DMEM medium supplemented with 10% fetal bovine serum, 50 g/ml L-ascorbic acid 2-phosphate, 10 nM dexamethasone and 10 mM -glycerophosphate at a density of 1 x 10(6) cells/dish in a 100-mm culture dish. The dental papilla-derived cells were then cultured for 6 weeks and the medium was changes every 3 days during the incubation period. Dental papilla-derived cells showed positive alkaline phosphatase (ALP) staining during 42 days of culture period. The formation of ALP stain showed its maximal manifestation at day 7 of culture period, then decreased in intensity during the culture period. ALP mRNA level was largely elevated at 1 weeks and gradually decreased with culture time. Osteocalcin mRNA expression appeared at day 14 in culture, after that its expression continuously increased in a time-dependent manner up to day 28. The expression remained constant thereafter. Runx2 expression appeared at day 7 with no detection thereafter. Von Kossa-positive mineralization nodules were first present at day 14 in culture followed by an increased number of positive nodules during the entire duration of the culture period. Osteocalcin secretion was detectable in the culture medium from 1 week. The secretion of osteocalcin from dental papilla-derived cells into the medium greatly increased after 3 weeks although it showed a shallow increase by then. In conclusion, our study showed that cultured human dental papilla-derived cells differentiated into active osteoblastic cells that were involved in synthesis of bone matrix and the subsequent mineralization of the matrix.]]>
Alkaline Phosphatase ; Ascorbic Acid ; Bone Matrix ; Dental Papilla ; Dental Sac ; Dentin ; Dexamethasone ; Enamel Organ ; Humans ; Mandible ; Molar, Third ; Osteoblasts ; Osteocalcin ; RNA, Messenger ; Stem Cells ; Tooth ; Tooth Germ ; Trypsin ; Young Adult

The author studied the dental arch widths and lengths height of palates at 2 groups of dentition : mixed dentition, early permanent dentition, young adult, having normal occlusion and dentition. The models of the 336 maxillary and mandibular casts, made from alginate-base hydrocolloid impressions were measured and analyzed statistically. The result as follows; 1. The upper intercanine width increased between the mixed dentition group and early permanent dentition group but there was no change in the young adult group in both sexes. Teh lower intercanine width increased between the mixed dentition group and early permanent dention group in the male. 2. The upper and lower 1st bimolar width increased slightly with age in the male but there was no change in the female. 3. The sex difference found in this study was one of absolute size, the female being slightly smaller than the male in the early permanent dentition group and young adult. 4. The arch length had no notable sexual differences and decreased between the mixed dentition group and early permanent dentition group. There was change in the arch length in the young adult. 5. The height of palate increased gradually with age.
Colloids ; Dental Arch* ; Dentition ; Dentition, Mixed ; Dentition, Permanent ; Female ; Humans ; Male ; Palate ; Sex Characteristics ; Young Adult*

A comparative stydy was undertaken to investigate the collapse of maxillary dental arch and palate in unilateral cleft lip and palate indivduals. The material for this study consisted of 39 subjects with repaired unilateral cleft lip and palate (30 males, 9 females). The measurements of unilateral cleft lip and palate individuals were compared with the measurements of normal indiviuals (30 males, 30 females). All the subjects were in the mixed dentition stage and the mean age was almost the same. The following conclusions were obtained. 1. A large number of the maxillary dental arch of the unilateral cleft lip and palate individuals showed omega-shape, and the arch sighificant difference between cleft group and group, but the intercanine width was mcuh smaller than that of normal individuals. 2. The palate of the unilateral cleft lip and palate subjects showed shorter and shallower form than that of normal subjects. 3. The palate area of the unilateral cleft lip and palate subjects was smaller than that of normal subjects, and the cleft side area was much smaller than the opposing side area. 4. There was no significant sexual difference in measurements of maxillary dental arch and palate of the unilateral cleft lip and palate subjects.
Cleft Lip* ; Dental Arch* ; Dentition, Mixed ; Humans ; Male ; Palate*

OBJECTIVE: To study the effects of mouth-breathing on maxillary arch development by comparing the palatal morphology of mouth- and nose-breathing children in mixed dentition. METHODS: Children in mixed dentition were enrolled and categorized into mouth-breathing (test group) and nose-breathing groups (control group) according to their breathing patterns. Children's plaster models were scanned with 3D laser scanner, and the 3D data were reconstructed and measured using Minics 15.0 and Geomagic 12.0 software. Measurement data (inter-molar width, palatal height, palatal volume, and palatal surface area) of the two groups were compared, and the correlation among the four measurement items was analyzed. RESULTS: The participants were 73 children (37 in test group and 36 in control group) with a mean age of (8.63±0.78) years old. The test group had significantly smaller inter-molar width, palatal volume, and palatal surface area but significantly higher palatal height than the control group (P<0.05). Inter-molar width and palatal volume were positively correlated with the palatal surface area in the test group (P<0.05). Inter-molar width and palatal height were positively correlated with the palatal surface area in the control group (P<0.01). CONCLUSIONS Mouth-breathing children have significantly reduced inter-molar width, palatal volume, and surface, and substantially increased palatal height, leading to different developmental patterns of the palatal morphology.
Child ; Dental Arch ; Dentition, Mixed ; Humans ; Maxilla ; Mouth Breathing ; Palate

OBJECTIVETo investigate the root canal curvature of permanent anterior teeth from Chuang population.

METHODS245 anterior teeth from Chuang population were collected and examined by X-ray radiography both from labiolingual and mesiodistal directions. For 218 type I anterior teeth, degree of root canal curvature, radius of curvature and length of the curved part of root canal were measured by a special electronic vernier caliper according to Schneider's and Schäfer's method and the data obtained were analyzed.

RESULTSRoot canals of anterior teeth from Chuang population were mainly of type I. The number of type II, III, IV were about 13 in mandibular central and 12 in mandibular lateral incisors. The incidence of curvature in maxillary central incisors, lateral incisors, canines and mandibular central incisors, lateral incisors, canines were 40%, 80%, 77%, 65%, 66%, 73% in mesiodistal directions, 62%, 69%, 70%, 62%, 41%, 61% in labiolingual directions respectively. The most curvature was moderate and happened in apical third. The heaviest curvature occurred in maxillary canines in mesiodistal direction and mandibular canines in labiolingual direction. The shortest radius and length of curvature occurred in maxillary lateral incisors.

CONCLUSIONRoot canal curvature of anterior tooth in Guangxi Chuang population is complex. The incidence of type II, III, IV is high in mandibular incisors.

China ; Cuspid ; Dental Pulp Cavity ; Dentition, Permanent ; Humans ; Incisor ; Mandible ; Root Canal Therapy

A T-box transcription factor gene, Tbx1 is a principal candidate of the most frequent chromosomal deletion syndrome found in human, DiGeorge/velocardiofacial syndrome which is a complex developmental disorder associated with cardiac outflow tract abnormalities, mid facial dysmorphology, velopharyngeal insufficiency and submucosal cleft palate. We performed in situ hybridization against mouse embryo from E13.5 (bud stage) to E18.5 (late bell stage) in order to analyze the expression patterns of Tbx1 in the developing mouse first molar, a derivative of the first pharyngeal arch. Tbx1 transcripts were found in the dental lamina and its surrounding mesenchyme at E13.5 and in the dental organ except enamel knot at E14.5 (cap stage). Tbx1 was strongly expressed in the cervical loop and stratum intermedium but was weak in the dental papilla and dental follicle at E15.5 (early bell stage). At E18.5, Tbx1 was strongly expressed not only in the dental organ (bell stage) except stellate reticulum but also dental papilla and dental follicle adjacent to the inner dental epithelium. In conclusion, Tbx1 transcripts were specifically expressed both in the dental epithelium and surrounding mesenchyme of developing tooth from initiation to bell stage, which were the most similar with those of Sox9 but little different from those of Pitx2 and ectodin. These results strongly suggested that Tbx1 may play a role as a transcription factor regulating proliferation and differentiation of both dental epithelium and mesenchyme through the tooth development.
Animals ; Branchial Region ; Cleft Palate ; Dental Enamel ; Dental Papilla ; Dental Sac ; Embryonic Structures ; Epithelium ; Humans ; In Situ Hybridization ; Mesoderm ; Mice* ; Molar* ; Reticulum ; Tooth ; Transcription Factors ; Velopharyngeal Insufficiency

There have been many radiographic studies on age estimation that evaluate reduction in size of dental pulp cavity with secondary dentin formation. The Paewinsky method reported high accuracy in estimating ages by measuring the width of the pulp cavity in panoramic radiographs. The aim of this study was to evaluate the application of the Paewinsky method to digital periapical radiographs. This study was conducted on 103 cases that reported to the Section of Human Identification of the National Forensic Service. The age was calculated by applying the Paewinsky method that measures the root and pulp canal width at three points in a tooth. The estimation results were compared with those calculated by the Johanson method. When the Paewinsky models were applied to digital periapical radiographs, the errors were significantly greater as compared to the original study. The errors of the maxillary second premolar and mandibular lateral incisor were greater than those of the maxillary central incisor, lateral incisor, mandibular canine, and first premolar. Furthermore, errors of the age estimation models in level C were greater than those in levels A and B. This study could be a reference for the application of the Paewinsky method to digital periapical radiographs.
Age Determination by Teeth ; Bicuspid ; Dental Pulp Cavity ; Dentin, Secondary ; Forensic Anthropology ; Incisor ; Methods ; Radiography, Dental ; Tooth

The purpose of this study was to estimate relative importance among the causative factors of arch length discrepancy(ALD) and possibility of prediction of the ALD in the mixed dentition. The sample consisted of the casts of the 142 young adults who had no abnormal muscle function. no skeletal abnormalities and Class I molar relationship. We classified the sample by gender and the extent of ALD, and measured mesiodistal diameters of each tooth and the dimensions of the dental arch. The computerized statistical analyses was carried out with SPSS win program. The results were as follows ; 1. Most of the variables of spacing group, and some variables of dental arch dimension of crowding group were significantly different between genders. But in normal group, there were few differences. 2. In male crowding and female spacing group, mainly measurements of tooth dimension were significantly different from those of normal group. 3. In male spacing and female crowding group, measurements of dental arch dimension were significantly different from those of normal group. 4. The measurements of dimension of dental arch were highly correlated with ALD in correlation analysis and factor analysis. 5. Prediction equations for adult's ALDs by means of what can be measured in the mixed dentition(mesiodistal dimensions of incisors and first molar, intermolar width and arch length) showed R square from 63% to 80 %.
Crowding ; Dental Arch ; Dentition, Mixed ; Female ; Humans ; Incisor ; Male ; Molar ; Tooth ; Young Adult