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

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

For the purpose of interpretation of positional changes of craniofacial structures in Class III malocclusion between mixed and permanent dentition, 73 normal samples and 103 Class III samples of mixed dentition and 125 normal samples and 168 Class III samples of permanent dentition were selected. Comparative cephalometric analysis was undertaken between them respectively by mesh diagram method to evaluate the positional changes of maxilla and mandible in anteroposterior direction and vertical direction and also the inclination changes of maxillary and mandibular incisors in labio-lingual direction. The following results were obtained: 1. The antero-posterior positional changes of the maxilla and mandible were posterior direction of maxilla and anterior direction of mandible. 2. The vertical positional changes of the maxilla and mandible were superior direction of both maxilla and mandible. 3. The labio-lingual inclination changes of the maxillary and mandibular incisors were lingual direction of both maxillary and mandibular incisors.
Dentition, Mixed ; Dentition, Permanent* ; Incisor ; Malocclusion* ; Mandible ; Maxilla

OBJECTIVE: The primary aim of the study was to generate new prediction equations for the estimation of maxillary and mandibular canine and premolar widths based on mandibular incisors and first permanent molar widths. METHODS: A total of 2,340 calculations (768 based on the sum of mandibular incisor and first permanent molar widths, and 1,572 based on the maxillary and mandibular canine and premolar widths) were performed, and a digital stereomicroscope was used to derive the the digital models and measurements. Mesiodistal widths of maxillary and mandibular teeth were measured via scanned digital models. RESULTS: There was a strong positive correlation between the estimation of maxillary (r = 0.85994, r2 = 0.7395) and mandibular (r = 0.8708, r2 = 0.7582) canine and premolar widths. The intraclass correlation coefficients were statistically significant, and the coefficients were in the strong correlation range, with an average of 0.9. Linear regression analysis was used to establish prediction equations. Prediction equations were developed to estimate maxillary arches based on Y = 15.746 + 0.602 × sum of mandibular incisors and mandibular first permanent molar widths (sum of mandibular incisors [SMI] + molars), Y = 18.224 + 0.540 × (SMI + molars), and Y = 16.186 + 0.586 × (SMI + molars) for both genders, and to estimate mandibular arches the parameters used were Y = 16.391 + 0.564 × (SMI + molars), Y = 14.444 + 0.609 × (SMI + molars), and Y = 19.915 + 0.481 × (SMI + molars). CONCLUSIONS: These formulas will be helpful for orthodontic diagnosis and clinical treatment planning during the mixed dentition stage.
Bicuspid* ; Dentition, Mixed ; Diagnosis ; Incisor* ; Linear Models ; Molar* ; Tooth

This purpose of this study was to investigate the differences in soft tissue characteristrcs according to the dental or skeletal dysplasia. For this purpose, lateral cephalogram of 153 children (Hellman dental age IIIB, control group 32, Angle Cl II. Div 1 malocclusion group 55, Angle Cl III group 66) were traced and measured. For these measurements, following conclusions were made. 1. FH A, FH Sn, FH UL, AA' of the Class III group were thicker than those of the normal and Class II group, but FH B, FH LL', BB' of the Class III group were not significantly different from those of the normal group. 2. FH B, FH LL, BB' of the Class II group were thicker than those of the normal and Class III group, but FH A, FH Sn, FH UL, AA' of the Class II group were not significantly different from those of the normal group. 3. Ans-Sn, FH P were not significantly different in three groups, while pp' of the Class III group was thicker than those of the other groups. 4. The lower lips of the Class II group were more anterioly everted with respect to the lower incisor inclination than those of the other groups. 5. The severity of skeletal dysplasia was partly camouflaged by the soft tissue.
Child* ; Dentition, Mixed* ; Humans ; Incisor ; Lip ; Malocclusion

The morphometric data which reflect the quality and quantity of the mandible are very important to the surgeon for the mandible. It is very useful clinically to predict the status of the mandible indirectly by other medical examinations. This study was undertaken to clarify the correlations of the mandible and dentition to predict the thickness and bone mineral density of the mandible. Sixty-one mandibles (32 M/29 F, mean age: 66.72 years) obtained from the collection of the Department of Anatomy and Cell Biology of Hanyang Medical College were analyzed. The bone mineral density was measured by dual energy X-ray absorptiometry. In the mandible, bone mineral densities at the mandiblular angle, between molars and premolars, around incisors and the thickness, and the length at the sections through the 1st and the 2nd molars were measured. The data were analysed with SPSS 12.0 program (One-Way ANOVA) according to age, gender and dentition, to verify the statistical significance and the correlation between the thickness and bone mineral densities. The obtained results were as follows. 1. The bone mineral density in the mandibular areas were variable, but statistically insignificant except incisor area. The bone density of the mandible was highly correlated with the thickness of cortical bones and the highest correlation coefficient was shown in sum of the thickness of buccal and lingual cortical bone (correlation coefficient, r=0.622) 2. The thickness of cortical bones at the sections through the molars in the man were greater than those in the woman. The correlation coefficient between the thickness and bone mineral density at the molars were greater in the woman. 3. The bone mineral density of whole mandible, the thickness of lingual and basal cortical bones and the height of alveolar ridge were significantly higher in the specimens with both of the 1st and 2nd mandibular molar teeth. The results of this study represents the significant differences of bone mineral density in the mandible according to gender and dentition and also the significant correlation between the bone mineral density and the thickness of cortical bone.
Absorptiometry, Photon ; Alveolar Process ; Bicuspid ; Bone Density ; Dentition ; Female ; Humans ; Incisor ; Mandible ; Molar

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

The aims of this study were to investigate the differences in the early craniofacial morphology of Class III malocclusions with good, fair and poor occlusal stability and to elucidate a key determinant for distinguishing the cases. Lateral cephalograms of 30 subjects with Class III malocclusion in the mixed dentition were analyzed at the start of treatment (mean age of 8.58+/-1.47). All subjects were re-evaluated after a mean period of 7.50+/-1.94 years comprising active treatment and retention. At this time, the samples were divided into three groups: good (10 subjects), fair (10 subjects) and poor (10 subjects) occlusal stability groups. According to the results of ANOVA, there were significant morphological differences in the early stage among the good, fair and poor occlusal stability groups, especially in variables that represented the vertical skeletal relationships. As well, there were already more dental compensations in the poor occlusal stability group. Stepwise discriminant analysis on the measurements at the time of first observation identified only one predictive variable: AB to mandibular plane angle (AB-MP). With this discriminant function, 83.3% of the original grouped cases were correctly classified and the canonical correlation coefficient was 0.857. In conclusion, AB-MP can be a possible predictor for the eventual prognosis of early Class III treatment. If it is below 60, the prognosis of early Class III treatment is expected to be poor, while if it is above 65, a good prognosis is expected.
Dentition, Mixed ; Malocclusion* ; Prognosis*

OBJECTIVEThe aim of this study was to measure and analyze the anatomic characteristics of the pulp chamber of Chinese permanent anterior teeth radiographically.

METHODSThere were 137 human permanent anterior teeth to be used. The crown length, crown width and crown thickness were measured by vernier caliper. Labial-lingual and mesial-distal radiographs were obtained by parallel technique and Photoshop 8.0 was adopted for measuring the largest labial-lingual length, the largest mesial-distal length, the pulp chamber height and the distance between the lingual surface of the crown and the corresponding wall of the pulp chamber; the ratios of the largest labial-lingual length to the crown thickness, the largest mesial-distal length to the crown width and the pulp chamber height to the crown length were calculated. Finally the coefficients of variance were caculated.

RESULTS(1) The ratios of the largest mesial-distal length to the crown width of maxillary and mandibular canines were statistically different from those of the other anterior teeth. There was not statistically significant difference for those ratios either between maxillary and mandibular canines or among incisors. (2) Indexes of the pulp chamber had higher variance than those of the external morphology. (3) The distance between the lingual surface of the crown and the corresponding wall of the pulp chamber had the smallest coefficient of variance. (4) The largest mesial-distal length of the pulp chamber had the largest coefficient of variance, except for the mandibular canines.

CONCLUSIONThis study provided anatomical basis for clinical work; the distance between the lingual surface of the crown and the corresponding wall of the pulp chamber could be used as a depth reference for the endodontic access, and the access should not be extended excessively in mesial-distal direction.

Asian Continental Ancestry Group ; China ; Crowns ; Cuspid ; Dental Pulp Cavity ; Dentition, Permanent ; Humans ; Incisor ; Lip ; Maxilla ; Tooth ; Tooth Crown ; Tooth Root

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