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At least 505 records · Page 28Linked to original sources

PubMed1989

The occurrence of tooth size discrepancies among different malocclusion groups.

This study consisted of 109 patients with varying malocclusions (Class I; Class II, Division 1; Division 2; and Class II surgery) who were treated orthodontically. Tooth size analyses were performed on the pretreatment models of these patients and mesial-distal tooth size ratios were measured as described by Bolton. The incidence of mesial-distal tooth size discrepancies in the malocclusion groups was analyzed and compared with Bolton's means and standard deviations. The results showed no difference in the incidence of tooth size discrepancies from one malocclusion group to another. When the sample was taken as a whole, there was no significant difference in the mean of the mesial-distal tooth size ratios as computed in the present study and compared to Bolton's mean. There were, however, higher standard deviations seen in the present study compared with Bolton's study. Even though there was no significant difference in the incidence of tooth size discrepancies among malocclusion groups, there was a large number of tooth size discrepancies in each group. Therefore it is suggested that Bolton's tooth size analysis be performed before initiation of orthodontic treatment.

Humans↗

PubMed2004

Fgf signaling is required for zebrafish tooth development.

We have investigated fibroblast growth factor (FGF) signaling during the development of the zebrafish pharyngeal dentition with the goal of uncovering novel roles for FGFs in tooth development as well as phylogenetic and topographic diversity in the tooth developmental pathway. We found that the tooth-related expression of several zebrafish genes is similar to that of their mouse orthologs, including both epithelial and mesenchymal markers. Additionally, significant differences in gene expression between zebrafish and mouse teeth are indicated by the apparent lack of fgf8 and pax9 expression in zebrafish tooth germs. FGF receptor inhibition with SU5402 at 32 h blocked dental epithelial morphogenesis and tooth mineralization. While the pharyngeal epithelium remained intact as judged by normal pitx2 expression, not only was the mesenchymal expression of lhx6 and lhx7 eliminated as expected from mouse studies, but the epithelial expression of dlx2a, dlx2b, fgf3, and fgf4 was as well. This latter result provides novel evidence that the dental epithelium is a target of FGF signaling. However, the failure of SU5402 to block localized expression of pitx2 suggests that the earliest steps of tooth initiation are FGF-independent. Investigations of specific FGF ligands with morpholino antisense oligonucleotides revealed only a mild tooth shape phenotype following fgf4 knockdown, while fgf8 inhibition revealed only a subtle down-regulation of dental dlx2b expression with no apparent effect on tooth morphology. Our results suggest redundant FGF signals target the dental epithelium and together are required for dental morphogenesis. Further work will be required to elucidate the nature of these signals, particularly with respect to their origins and whether they act through the mesenchyme.

Animals↗

PubMed1997

Reproduction of excursive tooth contact in an articulator with computerized axiography data.

PURPOSE: This study assessed the reproduction of excursive tooth contacts with a SAM2 "P" articulator set up with the aid of computerized axiography. MATERIAL AND METHODS: Articulator excursive tooth contacts were compared with intraoral excursive contacts identified with occlusogram wax. The maxillary casts were mounted with a kinematic face-bow, and the mandibular cast was oriented to the intercuspal position. The articulator was set using information obtained from computerized axiography. Protrusion and laterotrusion to the left and right sides were examined. The first 4 mm of excursive tooth contacts in the occlusogram were compared with the 4 mm of excursive tooth contacts in the articulator. RESULTS: The articulator reproduced 82% of the teeth with protrusive tooth contacts and 90% of the teeth with laterotrusive tooth contacts. The exact locations of excursive tooth contacts were reproduced in 66% of protrusive contacts and 81% of laterotrusive contacts. The articulator also created additional eccentric dental contacts that were not originally present in the occlusogram. Twenty percent of the subjects showed these additional contacts during protrusion; in lateral movement of the articulator these additional contacts were present in 27% to the left side and 20% to the right. Clinically, these findings suggest that there are limits to the ability of the articulator to reproduce excursive tooth contacts. These limitations should be kept in mind when an articulator is used for diagnostic and restorative dental procedures.

Adolescent↗

PubMed2001

Permanent tooth crown dimensions in prematurely born children.

AIM: The aim was to examine the effect of preterm birth on permanent tooth crown dimensions. MATERIALS AND METHODS: The data consisted of 328 prematurely born white and black children and 1804 control children who participated in the cross-sectional study of the Collaborative Perinatal Project (USA) in the early 1960s and 1970s. The dental examinations were carried out in a standardized fashion at ages varying from 6 to 12 years in 95% of cases. Tooth crown size measurements were performed on the dental casts with an electronic measuring device and readout by two experienced observers according to precise definitions generally quoted in the anthropological and genetic literature. The preterm and control groups were divided by sex and race. RESULTS: The results show both increased and decreased tooth crown dimensions in the prematurely born children. Significantly increased dimensions were found in the means of the intercuspal distances of the first permanent molars in the white boys and in the mesiodistal dimensions (MD) of the lower lateral incisors and the upper left first molar in the black girls. By contrast, there were decreased intercuspal distances, MD and labiolingual (LL) tooth crown dimensions in the white girls and black boys. The statistical method used was the Mann-Whitney's U-test (Willcoxon Rank-Sums test). CONCLUSIONS: The findings partly support previous reports of decreased tooth crown dimensions in preterm infants, but the increased dimensions found in the preterm white boys and black girls differ from earlier reports. Our results indicate the importance of environmental factors including neonatal factors in determining permanent tooth crown dimensions. Growth patterns, the buffering capacity and the timing of sensitive moments in tooth crown volume gain may vary between the sexes and ethnic groups and the possible effect of the accelerated growth period in preterm infants (catch-up growth) may influence the determination of permanent tooth crown dimensions.

Adolescent↗

PubMed2000

Transgenically ectopic expression of Bmp4 to the Msx1 mutant dental mesenchyme restores downstream gene expression but represses Shh and Bmp2 in the enamel knot of wild type tooth germ.

Bmp4 is a downstream gene of Msx1 in early mouse tooth development. In this study, we introduced the Msx1-Bmp4 transgenic allele to the Msx1 mutants in which tooth development is arrested at the bud stage in an effort of rescuing Msx1 mutant tooth phenotype in vivo. Ectopic expression of a Bmp4 transgene driven by the mouse Msx1promoter in the dental mesenchyme restored the expression of Lef-1 and Dlx2 but neither Fgf3 nor syndecan-1 in the Msx1 mutant molar tooth germ. The mutant phenotype of molar but not incisor could be partially rescued to progress to the cap stage. The Msx1-Bmp4 transgene was also able to rescue the alveolar processes and the neonatal lethality of the Msx1 mutants. In contrast, overexpression of Bmp4 in the wild type molar mesenchyme down-regulated Shh and Bmp2 expression in the enamel knot, the putative signaling center for tooth patterning, but did not produce a tooth phenotype. These results indicate that Bmp4 can bypass Msx1 function to partially rescue molar tooth development in vivo, and to support alveolar process formation. Expression of Shh and Bmp2 in the enamel knot may not represent critical signals for tooth patterning.

Alleles↗

PubMed2001

Expression of class 3 semaphorins and neuropilin receptors in the developing mouse tooth.

The semaphorins are a large family of secreted or cell-bound signals needed for the development of the nervous system. We compared mRNA expression of class 3 semaphorins (Sema3A, 3B, 3C and 3F) and their two receptors (Neuropilin-1 and -2) in the embryonic mouse first molar tooth germ (E10-18) by radioactive in situ hybridization. All genes showed distinct developmentally regulated expression patterns during tooth organogenesis. Interestingly, Sema3A and 3C were first detected in the early dental epithelium, and later both genes were present in the epithelial primary enamel knot, a putative signaling center of the embryonic tooth regulating tooth morphogenesis. Prior to birth, Sema3A was also observed in tooth-specific cells, preodontoblasts, which later differentiate into odontoblasts secreting dentin, and in the mesenchymal dental follicle cells surrounding the tooth germ. Sema3B appeared transiently in the dental mesenchyme in the bud and cap stage tooth while Sema3F was expressed in both epithelial and mesenchymal components of the tooth. Of note, Npn-1 expression pattern was largely complementary to that of Sema3A, and transcripts were restricted to the dental mesenchymal cells. Npn-1 expression was first seen in the developing dental follicle, and later transcripts also appeared in the dental papilla mesenchyme. In contrast, Npn-2 signal was seen in both epithelial and mesenchymal tissues such as in the primary enamel knot and preodontoblasts.

Animals↗

PubMed2000

A new method for qualitative and quantitative evaluation of tooth displacement under the application of orthodontic forces using magnetic sensors.

The purpose of this study was to develop a new method for the quantitative and qualitative measurement of tooth displacement under load and to clarify the relationship between the force system acting on a tooth and a resultant movement. A combination of eight magnetic sensors and a magnet was employed to measure three-dimensional displacement. Two sets of sensors and a magnet were placed in front and at the back of a front tooth subjected to orthodontic forces. Magnets and sensors were fixed to the subject tooth and posterior teeth, respectively. Sensors detected displacements of two magnets extended from the subject tooth separately in real time. The tooth trajectories projected on the sagittal plane were studied. From displacements of two magnets, angle of tooth rotation, the position of center of rotation and the amount and direction of displacement of an arbitrary point on the tooth could be calculated with high accuracy. Also, the location of center of resistance could be determined. It was found that the center of rotation is moving substantially even with a small difference in the level of force application. Furthermore, a small amount of displacement of the center of resistance was observed with varying the force magnitude.

Biomechanical Phenomena↗

PubMed2005

Intermaxillary tooth size discrepancy and malocclusion: is there a relation?

The aims of this study were to identify the possible sex differences in tooth size ratios between males and females, to determine whether there is a difference in the incidence of tooth size discrepancies for both the anterior and overall ratios when comparing with Angle Class I; Class II, division 1; Class II, division 2; and Class III malocclusion groups, to compare the tooth size ratios of different malocclusion groups with the anterior and overall tooth size ratios of 150 untreated normal occlusion subjects. In addition, the aim was to determine the percentage of tooth size discrepancies outside 2 SD from Bolton means for tooth ratios present in each malocclusion group and in the overall sample of this study. This study consisted of 150 subjects who served as the normal occlusion group and 560 patients who showed four different malocclusion characteristics (Angle Class I; Class II, division 1; Class II, division 2; and Class III). Tooth size measurements were performed on the models of normal occlusion and pretreatment models. For statistical evaluation, Student's t-test, analysis of variance and Tukey Honestly Significant Difference tests were performed. A significant sex difference was found only in the overall ratio for normal occlusion subjects (P < .001). All malocclusion groups showed statistically significant higher overall ratios than the normal occlusion group (P < .001). There were no statistically significant differences among malocclusion groups; however, there were a large number of patients within each group who had discrepancies greater than 2 SD from the mean. Further investigations are needed to explain the probable racial differences and relationships between malocclusion and tooth size measurements.

Adult↗

PubMed1996

Incremental lines of von Ebner in dinosaurs and the assessment of tooth replacement rates using growth line counts.

Dinosaur dentine exhibits growth lines that are tens of micrometers in width. These laminations are homologous to incremental lines of von Ebner found in extant mammal and crocodilian teeth (i.e., those of amniotes). The lines likely reflect daily dentine formation, and they were used to infer tooth development and replacement rates. In general, dinosaur tooth formation rates negatively correlated with tooth size. Theropod tooth replacement rates negatively correlated with tooth size, which was due to limitations in the dentine formation rates of their odontoblasts. Derived ceratopsian and hadrosaurian dinosaurs retained relatively rapid tooth replacement rates through ontogeny. The evolution of dental batteries in hadrosaurs and ceratopsians can be explained by dentine formation constraints and rapid tooth wear. In combination with counts of shed dinosaur teeth, tooth replacement rate data can be used to assess population demographics of Mesozoic ecosystems. Finally, it is of historic importance to note that Richard Owen appears to have been the first to observe incremental lines of von Ebner in dinosaurs more than 150 years ago.

Animals↗

PubMed2003

Lineage of non-cranial neural crest cell in the dental mesenchyme: using a lacZ reporter gene during early tooth development.

The tooth is one of the ectodermal organs controlled by reciprocal interactions between the epithelium and the mesenchyme. Mesenchymal cells in the developing tooth, so-called dental mesenchymal cells, are derived from two different origins: the cranial neural crest (CNC) and the non-CNC. These CNC-derived cells migrate, proliferate and differentiate into odontoblasts, cementoblasts, fibroblasts, osteoblasts and chondroblasts. Tooth germs of wild-type mice were transplanted into the kidney of adult lacZ-transgenic mice. After 1 week of transplantation, a few lacZ-expressing cells and many red blood cells were found near or inside the blood vessels in the pulp of wild-type tooth germs. This result shows that circulating cells of the adult host could invade the dental pulp during tooth development, through the blood vessels, and be a part of dental pulp tissue. Therefore, it can be suggested that these circulating progenitor cells could be the origin of non-CNC-derived cells in tooth germ and their migration pathways would be the blood vessels invading the dental pulp during tooth development. If variations of this experiment were suitably adjusted, such as the embryonic stage of the tooth germ, duration of transplantation, etc., this transplantation experiment using adult lacZ-transgenic mice could be a good system to reveal the origin and migration pathway of cells in developing organs as well as in dental mesenchymal cells.

Animals↗

PubMed2004

Incidence of tooth loss and prosthodontic dental care: effect on chewing difficulty onset, a component of oral health-related quality of life.

OBJECTIVES: To quantify incidence of tooth loss, prosthodontic dental restoration, and chewing difficulty onset and the effect of tooth loss and prosthodontic restoration on chewing difficulty onset. DESIGN: A prospective cohort study of oral health and related behaviors with in-person interviews and clinical examinations conducted at baseline and 24 months. Telephone interviews were conducted every 6 months between these sessions. SETTING: A community-based sample of four counties in north Florida. PARTICIPANTS: Eight hundred seventy-three persons who had at least one tooth and were aged 45 and older at baseline. MEASUREMENTS: Persons were queried regarding onset of chewing difficulty, an important component of oral health-related quality of life (OHRQoL). The chewing index of Leake, with minor revision, was the primary outcome of interest. Tooth loss was measured using direct clinical examination. Dental care use was reported during each interview. RESULTS: Approximately 22% of participants reported tooth loss during follow-up. Fixed prosthodontics (crowns and bridges) was the most common form of new prosthodontic treatment. People who reported tooth loss were 2.7 times more likely to report chewing difficulty onset than people without tooth loss (P<.001). Having fewer occluding pairs of teeth at baseline was significantly associated with an increased probability of chewing difficulty onset. People who received removable prosthodontic treatment were much less likely to report chewing difficulty onset than people who did not (P<.01). CONCLUSION: Incident tooth loss and removable prosthodontic restoration strongly predicted chewing difficulty, an important component of OHRQoL.

Aged↗

PubMed1997

Intrusion of teeth in the combination implant-to-natural-tooth fixed partial denture: a review of the theories.

This article reviews the literature dealing with the combination implant-to-natural-tooth-supported fixed partial denture. The restoration of masticatory function with a combination implant-to-natural-tooth fixed partial denture is associated with a variety of undesirable clinical sequelae, including the breakage of implant components, damage to the abutment teeth, or intrusion of the abutment teeth. Theories regarding intrusion of abutment teeth combined with implants for fixed partial dentures are only speculative. Several theories are presented to explain the intrusion of natural teeth in association with implant-to-natural-tooth fixed partial dentures. One of the first theories was based on the idea that a lack of normal stimulation of the periodontal ligament produces atrophy of the periodontal ligament and intrusion of the tooth. The remaining theories relate to excessive forces being placed on the natural tooth, resulting in movement of the tooth to a less stressful position. These forces are placed on the tooth by differential energy dissipation, mandibular flexion and torsion, flexion of the fixed partial denture framework, impaired rebound memory, debris impaction or microjamming, or ratchet effect related to the use of precision attachments. Based a review of the literature, a philosophy for treating combination implant-to-natural-tooth restorations is presented.

Biomechanical Phenomena↗

PubMed1981

Assessment of tooth mobility using small loads. IV. The effect of periodontal treatment including gingivectomy and flap procedures.

Tooth mobility at loads below 100 p, gingival fluid amounts and bone score heights were studied in five subjects. In all 28 maxillary anterior teeth were investigated during a period of 68 weeks. In order to enlarge upon a previous investigation of tooth mobility following periodontal surgery (Persson 1980), the effects on tooth mobility of gingivectomy and flap procedures were compared. A split-mouth technique was used for the two surgical procedures which were performed during one session. No preoperative differences of the investigated parameters were found. During the first weeks after surgery, an increase of tooth mobility was seen which amounted to +80% maximum (flap side) and +13.1% (gingivectomy side). The final tooth mobility changes were -60% on the flap side and -40% on the gingivectomy side. No significant differences of tooth mobility were found between the two surgical methods. The present findings of tooth mobility following surgery also indicated a considerable time lapse before any major decrease of tooth mobility took place.

Adult↗

PubMed2005

Tooth loss among habitual chewing-stick and plastic toothbrush users in the adult population of Mtwara, rural Tanzania.

OBJECTIVES: The aim of this study was to determine the extent and type of tooth loss in relation to habitual chewing-stick (CS) and plastic toothbrush (PT) users in adults. METHODS: A cross-sectional descriptive study was conducted in Mtwara's rural population aged >or=40 years. A total of 206 randomly selected study participants - males (55.8%) and females (44.2%) - were interviewed on oral hygiene practices using a structured questionnaire, and a clinical examination performed for assessment of tooth loss. RESULTS: Of the total, 93.2% were partially edentulous, 2.4% completely edentulous and those with no tooth loss 4.4%. The total number of missing teeth were 1728 (mean, 8.38 +/- 7.9), and the causes were caries (74.9%), mutilation (4.8%) and others including periodontal and trauma (20.3%). There was no significant difference in the mean number of tooth loss between the upper and lower jaw, and between males and females. However, the mean number of missing teeth in the lower jaw was higher in females than in males (P = 0.04), and on lower left than lower right jaw (P = 0.008). Lower molars, especially first molars, were the teeth lost most often. Tooth-cleaning devices included PT (51.5%), CS (25.7%), both type (BT; 17.0%) and unspecified (5.8%). The differences in the mean number of missing teeth were higher in CS than habitual PT users (P = 0.024) and in BT (P = 0.029). Tooth loss was also higher among those who brushed once when compared with those who brushed two times or more per day (P = 0.046). CONCLUSION: Tooth loss was significantly higher in CS than PT habitual users and affected mostly the lower molars and especially the first molar. However, for economical reasons, effective use of CS should be promoted for enhanced tooth retention.

Adult↗

PubMed1985

Orally administered methionine alters the growth of tooth germs in newborn rats.

The effects of methionine intubation via gastric needle on the growth of incisor and molar tooth germs in newborn rats were investigated. Upon delivery, the pups were divided into groups of 8 and randomly assigned to dams which were then randomly assigned to three groups. Then the pups were intubated in the stomach with (a) no methionine - group I, (b) 0.1 g methionine per 100 g body weight - group II, or (c) 0.2 g methionine - group III, from day 3 to day 13 on every other day. At day 15, the average body weights of pups among the three groups showed no difference statistically, though animals in group III showed a 17.5% mortality rate; there were no deaths in the other two groups. There was inadequate hair growth in some pups in group III. The weights of incisor and of molar tooth germs in group II were heavier than in groups I and III. The total hydroxyproline content of incisor tooth germs in group II was also greater than in the other groups, whereas there was no difference in molar tooth germs on this parameter among all groups. Collagen synthesis of both tooth germs was highest in group III compared to other groups. The total amount of calcium in both tooth germs showed no difference among groups, but values were consistently higher in group II. 45Ca uptake showed no difference among groups. The present results indicate that the amount of methionine received by growing pups alters the composition of developing tooth germs, but that incisor and molar tooth germs are affected differently.

Administration, Oral↗

PubMed2001

Regulation of tooth development by the novel type I TGFbeta family member receptor Alk8.

We have recently identified, in zebrafish, a novel type I receptor of the TGFbeta family, alk8, that participates in Bmp signaling pathways to mediate early dorsoventral patterning of neurectodermal and mesendodermal tissues. Since Bmps play significant roles in tooth specification, initiation, and differentiation, we hypothesized that alk8 may play a role in directing the Bmp-mediated epithelial mesenchymal cell interactions regulating tooth development. Immunohistochemical analysis demonstrates that Alk8 is expressed in developing zebrafish and mouse teeth. Examination of tooth development in zebrafish with disrupted alk8 signaling revealed specific defects in tooth development. Ectopic expression of constitutively active Alk8 results in the formation of elongated tooth structures, while expression of dominant-negative Alk8 results in arrested tooth development at the bud stage. These results are consistent with the established requirements for Bmp signaling in tooth development and demonstrate that Alk8 is a key regulator of tooth development.

Activin Receptors, Type I↗

PubMed1995

Three-year tooth loss among black and white older adults in North Carolina.

The distribution and determinants of tooth loss in older adults are poorly defined, especially in Blacks, who have been underrepresented in previous studies. This study investigated, epidemiologically, the distribution and predictors of tooth loss in elder Blacks and Whites by following a random sample of older adults in North Carolina for three years. It was hypothesized that Blacks would be at greater risk of tooth loss and would have different risk factors for tooth loss. Data from 263 Blacks and 228 Whites were collected by dental examinations and interviews conducted in the participants' homes. During the three-year follow-up, 53% of Blacks and 29% of Whites lost at least one tooth. Blacks lost 13% of their remaining teeth compared with 4% for Whites. Logistic regression models showed that factors related to tooth loss for Blacks were: more S. mutans in stimulated saliva, deeper periodontal pockets, more P. intermedia in subgingival plaque, high blood pressure, limited help from others, and few symptoms of depression. For Whites, significant factors were: more lactobacilli in stimulated saliva, history of current oral pain at baseline, more alcohol consumption, no history of past use of calcium or xerostomic medications, higher income, lower occupational prestige, and increased numbers of negative life events. This study showed that older Blacks were at greater risk of tooth loss than older Whites. For both races, factors such as oral bacteria, periodontal conditions, oral symptoms, and psychosocial and economic factors are related to increased risk of tooth loss.

Black or African American↗

PubMed1998

FGFs and BMP4 induce both Msx1-independent and Msx1-dependent signaling pathways in early tooth development.

During early tooth development, multiple signaling molecules are expressed in the dental lamina epithelium and induce the dental mesenchyme. One signal, BMP4, has been shown to induce morphologic changes in dental mesenchyme and mesenchymal gene expression via Msx1, but BMP4 cannot substitute for all the inductive functions of the dental epithelium. To investigate the role of FGFs during early tooth development, we examined the expression of epithelial and mesenchymal Fgfs in wild-type and Msx1 mutant tooth germs and tested the ability of FGFs to induce Fgf3 and Bmp4 expression in wild-type and Msx1 mutant dental mesenchymal explants. Fgf8 expression is preserved in Msx1 mutant epithelium while that of Fgf3 is not detected in Msx1 mutant dental mesenchyme. Moreover, dental epithelium as well as beads soaked in FGF1, FGF2 or FGF8 induce Fgf3 expression in dental mesenchyme in an Msx1-dependent manner. These results indicate that, like BMP4, FGF8 constitutes an epithelial inductive signal capable of inducing the expression of downstream signaling molecules in dental mesenchyme via Msx1. However, the BMP4 and FGF8 signaling pathways are distinct. BMP4 cannot induce Fgf3 nor can FGFs induce Bmp4 expression in dental mesenchyme, even though both signaling molecules can induce Msx1 and Msx1 is necessary for Fgf3 and Bmp4 expression in dental mesenchyme. In addition, we have investigated the effects of FGFs and BMP4 on the distal-less homeobox genes Dlx1 and Dlx2 and we have clarified the relationship between Msx and Dlx gene function in the developing tooth. Dlx1,Dlx2 double mutants exhibit a lamina stage arrest in maxillary molar tooth development (Thomas B. L., Tucker A. S., Qiu M. , Ferguson C. A., Hardcastle Z., Rubenstein J. L. R. and Sharpe P. T. (1997) Development 124, 4811-4818). Although the maintenance of molar mesenchymal Dlx2 expression at the bud stage is Msx1-dependent, both the maintenance of Dlx1 expression and the initial activation of mesenchymal Dlx1 and Dlx2 expression during the lamina stage are not. Moreover, in contrast to the tooth bud stage arrest observed in Msx1 mutants, Msx1,Msx2 double mutants exhibit an earlier phenotype closely resembling the lamina stage arrest observed in Dlx1,Dlx2 double mutants. These results are consistent with functional redundancy between Msx1 and Msx2 in dental mesenchyme and support a model whereby Msx and Dlx genes function in parallel within the dental mesenchyme during tooth initiation. Indeed, as predicted by such a model, BMP4 and FGF8, epithelial signals that induce differential Msx1 and Msx2 expression in dental mesenchyme, also differentially induce Dlx1 and Dlx2 expression, and do so in an Msx1-independent manner. These results integrate Dlx1, Dlx2 and Fgf3 and Fgf8 into the odontogenic regulatory hierarchy along with Msx1, Msx2 and Bmp4, and provide a basis for interpreting tooth induction in terms of transcription factors which, individually, are necessary but not sufficient for the expression of downstream signals and therefore must act in specific combinations.

Animals↗