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

Humans ; Malocclusion ; therapy ; Molar, Third ; growth & development ; pathology ; Orthodontics, Corrective ; Tooth Eruption ; Tooth Loss ; pathology ; Tooth Movement Techniques

PURPOSE: The purpose of this animal study was to perform a histological and histomorphometric analysis in order to elucidate the effect of fibroblast growth factor-2 (FGF-2) on injured periodontal ligament (PDL) and cementum after tooth replantation in dogs. METHODS: The roots of 36 mandibular premolars from six mongrel dogs were used in this study. The roots were randomly divided into three groups: (1) a positive control group (n=12), in which the PDL was retained; (2) a negative control group (n=12), in which the PDL and the cementum between the notches were removed; and (3) an experimental group (n=12), in which the PDL and the cementum between the notches were removed and the roots were soaked in an FGF-2 solution (30 microg/0.1 mL). After treating the root surfaces, the extracted roots were replanted into extraction sockets. The animals were sacrificed four and eight weeks after surgery for histologic and histomorphometric evaluation. RESULTS: At four and eight weeks, normal PDLs covered the roots in the positive control group. In the negative control group, most replanted roots showed signs of replacement resorption. In the experimental group, new PDL-like tissue and cementum-like tissue were observed to partially occupy the region between the root surfaces and the newly formed bone. Histomorphometric analysis showed that the mean length of the newly formed cementum-like tissue on the roots treated with FGF-2 was significantly greater than that of the tissue on the roots in the negative control group (four weeks, P=0.008; eight weeks, P=0.042). However, no significant differences were observed between the roots treated with FGF-2 and the negative control roots with respect to newly formed PDL-like tissue. CONCLUSIONS: The results of this study suggest that use of FGF-2 on injured root surfaces promotes cementogenesis after tooth replacement in dogs.
Animals ; Bicuspid ; Cementogenesis ; Dental Cementum* ; Dogs* ; Fibroblast Growth Factor 2 ; Fibroblast Growth Factors* ; Periodontal Ligament* ; Periodontium ; Regeneration ; Tooth ; Tooth Replantation*

OBJECTIVETo investigate the changes of available spaces of posterior arch segments in mandibular dentition from 13 to 18 years of age, which would provide information for space analysis of whole dental arch in adolescents.

METHODSTwenty-six adolescents (12 males, 14 females) with normal occlusion were selected. All of the subjects had lateral cephalograms taken at the same time each year for 6 years. Longitudinal cephalometry and statistic analysis were conducted for all subjects.

RESULTSSignificant differences of available space were found between males and females. The growth of available space from 13 to 18 years of age was 5.12 mm in females and 5.79 mm in males. The completion of mandibular remodeling in males lagged behind females for about 1 year. No significant increase was found in girls beyond 16 years and in boys beyond 17 years. There was a 1.22 mm increase on each side per year in females until 16 years and a 1.45 mm increase in males until 17 years. The increase of available space was made partly by resorption of bone from the anterior border of the ramus and partly by mesial movement of the first molar. The mesial movement of dental arch was probably stimulated by the eruption of the third molars.

CONCLUSIONSThe prediction of available space should be based on age and sex.

Adolescent ; Age Factors ; Cephalometry ; Dental Arch ; growth & development ; Female ; Humans ; Longitudinal Studies ; Male ; Mandible ; growth & development ; Molar, Third ; growth & development ; Orthodontics, Corrective ; Sex Factors ; Tooth Eruption ; Tooth Migration

The purpose of this study id to investigate the change of the EGFR mRNA expression in the rat gingival epithelium by the experimental tooth movement. We applied reciprocal force between the upper anterior teeth using NiTi open coil spring and stainless steel wire for 1, 2 3, 7 days. For the detection of EGFR mRNA, in situ hybridization was done in the tissue samples which were taken from the pressure and tension sides of teeth. The results were as follows; 1. The expression of EGFR mRNA was increased application-time dependently. a Day 1: mild expression on the basal and spinous cell layers. b. Day 2: moderate expression on the whole layers. c. Day 3: severe expression on the basal and spinous cell layers. d. Day 7: severe expression on the whole layers 2. The expression level of EGFR mRNA in the pressure and tension sides were similar during the whole period of experiment except seven day application at which the cornified layer of the tension side showed moderate expression. 3. Removal of the appliance after 7-day force application lowered the level of EGRF mRNA expression. It was returned to the mild and control (rare) level at three and seven days after the removal, respectively. In conclusion, EFGR mRNA was increased by, the experimental tooth movement on the rat ginigval epithelium. Up-regulation of EGFR mRNA in the gingival epithelium can be regarded as responses to the possible changes caused byy the physical stersses to the oral environment to maintain the homeostatic conditions of the periodontium.
Animals ; Epithelium ; Homeostasis ; In Situ Hybridization ; Periodontium ; Rats* ; Receptor, Epidermal Growth Factor ; RNA, Messenger ; Stainless Steel ; Tooth Movement* ; Tooth* ; Up-Regulation

Traumatic dental injury is considered a public dental health problem because of a high childhood incidence, high treatment costs, and prolonged treatment time. Although management guidelines for traumatized teeth have been outlined, tooth loss following trauma is occasionally unavoidable. Here, we describe the successful interdisciplinary management of a traumatized central incisor in an 11-year old boy that was extracted because of a poor prognosis and restored by the autotransplantation of an immature donor tooth into the site. The patient underwent orthodontic treatment in order to close the donor site space and bring the autotransplanted tooth to an ideal position. Postorthodontic treatment radiographs and photographs revealed an esthetic and functional natural tooth replacing the lost tooth. The findings from this case suggest that autotransplantation offers unique advantages as a treatment modality for the restoration of missing teeth, particularly in growing children.
Autografts* ; Child ; Growth and Development ; Health Care Costs ; Humans ; Incidence ; Incisor ; Male ; Prognosis ; Tissue Donors ; Tooth ; Tooth Loss ; Transplantation ; Transplantation, Autologous*

The bone morphogenetic protein (BMP) family is an important factor in the regulation of cell ular life activities and in the development of almost all tissues. BMP-mediated signaling plays an important role in tooth root development, which is a part of tooth development. Epithelial and mesenchymal interactions are involved in tooth root development, but the BMP signaling pathway has a different effect on tooth root development in epithelial and mesenchymal. This review summarizes the advances of BMP signaling in tooth root development.
Bone Morphogenetic Protein 2 ; Bone Morphogenetic Protein 7 ; Bone Morphogenetic Proteins ; physiology ; Odontogenesis ; Signal Transduction ; Tooth ; Tooth Root ; growth & development

OBJECTIVE: The objective of this study is to investigate the eruption pattern and root resorption of the bovine anterior dentition in relation to growth-related parameters based on dental maturity. METHODS: A cross-sectional study was conducted on 110 bovine anterior mandibles by using standard radiography, cone-beam computed tomography (CBCT), and actual measurements. We determined the relationships between the stages of dental maturity by using a modification of Demirjian's method and various growth-related parameters, such as the activity of the root-resorbing tissue and mobility of the deciduous teeth. The correlation of growth-related parameters with interdental spacing and distal unusual root resorption (DRR) of the deciduous fourth incisor was assessed. The cause of mesial unusual root resorption (MRR) of the deciduous fourth incisor was determined on the basis of the arrangement of the permanent third incisor. RESULTS: An independent t-test and chi-square test indicated significant differences in growth-related parameters associated with dental arch length discrepancy and factors related to the shedding of deciduous teeth between the low and high dental maturity groups. The samples with interdental spacing and DRR showed a larger sum of mesiodistal permanent crown widths and higher dental maturity than did the respective controls. Samples with MRR tended to show a lingually rotated distal tip of the adjacent tooth crown. CONCLUSIONS: Dental maturity has relevance to the interdental spaces and unusual root resorption of mixed dentition. The position of the adjacent tooth crown on CBCT may be correlated with the occurrence of unusual root resorption of the incisor.
Cone-Beam Computed Tomography ; Cross-Sectional Studies ; Crowns ; Dental Arch ; Dentition ; Dentition, Mixed ; Growth and Development ; Incisor* ; Mandible ; Methods ; Radiography ; Root Resorption* ; Tooth Crown ; Tooth* ; Tooth, Deciduous

Tooth bleaching agents contain powerful oxidizing agents, which serve as the main part of bleaching agents because of its release of effective bleaching component. It has been a hot topic whether tooth bleaching agents exert negative influence on oral health. In order to provide train of thoughts and reference for further clinical researches and treatments, this review paper focuses on bleaching agents' effects on the growth of oral microbes and the formation of biofilms.
Bacteria ; drug effects ; growth & development ; Biofilms ; drug effects ; growth & development ; Humans ; Hydrogen Peroxide ; Mouth ; microbiology ; Oral Health ; Oxidants ; pharmacology ; Tooth Bleaching ; Tooth Bleaching Agents ; pharmacology

Russell-Silver syndrome (RSS) is a congenital disease characterized by short stature due to growth hormone deficiency, physical asymmetry, inverted triangular face, micrognathia, prominent forehead, and hypodontia. This case report presents a prosthetic management of a 6-year-old patient with Russell-Silver syndrome treated with overdentures on the maxilla and the mandible using the remaining primary teeth. Subsequent and comprehensive dental management considering the growth and development of a young patient will be necessary.
Anodontia ; Child ; Denture, Overlay ; Forehead ; Growth and Development ; Growth Hormone ; Humans ; Mandible ; Maxilla ; Silver-Russell Syndrome* ; Tooth, Deciduous