Odontogenesis

Introduction: True regeneration of the dental pulpdentin complex in immature teeth with necrotic pulps has not been shown histologically. It is not known to what extent this true tissue regeneration is necessary to achieve clinically acceptable outcomes. Methods: This case report describes the treatment of a patient with an immature maxillary right central incisor with a history of impact trauma and enamel-dentin crown fracture. A diagnosis of pulp necrosis with acute apical abscess was established. A regenerative endodontic protocol that used a paste containing Augmentin for 5 weeks as an intracanal medicament was used. Results: Follow-ups at 9, 12, 17, and 31 months revealed complete osseous healing of the periapical lesion and formation of the root apex, but without increase in root length. Clinically, the tooth was functional, asymptomatic, and nonresponsive to pulp vitality tests. The crown discolored over time. On reentering the root canal, no tissues were observed under magnification inside the root canal space. The root canal treatment was completed with mineral trioxide aggregate obturation. Conclusions: Augmentin might be an acceptable choice for root canal disinfection in regenerative endodontic procedures. The protocol for regenerative endodontic treatment is not predictable for pulp-dentin regeneration. Formation of the root apex is possible without pulp regeneration. (J Endod 2013;39:1291-1295

Authors -Proffit WR, Frazier-Bowers SA Objectives -To review pre-and post-emergent eruption, with particular emphasis on distinguishing isolated molar ankylosis from primary failure of eruption (PFE) and genetic considerations in eruption problems. Material and Methods -Radiographic review of eruption failure patients; animal and human experiments; high precision observations of movements of erupting teeth.

Biomimicry has been introduced as a term for innovations inspired by nature [1]. Such innovations may appear in almost every part of modern society. This review on the effects of enamel matrix proteins on the formation of cementum and the development of emdogain for regeneration of periodontal tissues lost due to periodontitis shows an example of biomimicry in dentistry. Findings from clinical and laboratory investigations are summarized and the biological basis for enamel matrix-induced periodontal regeneration is discussed.

Carious pulp exposure in permanent molars of children is a common incident. Mineral trioxide aggregate is a new material that possesses numerous exciting possibilities for pulp therapy. Aim: The purpose of this study was to evaluate the efficiency of MTA as a direct pulp capping agent in young permanent teeth. Methods: Thirty asymptomatic permanent molars with pulp exposures were treated by pulp capping using MTA. At each recall (6, 12, 18 and 24 months), the teeth were assessed clinically, through pulpal sensitivity tests, as well as radiographically to evaluate periapical healing. Results: None of the cases reported spontaneous pain at the six months follow up and the pulp showed signs of vitality and absence of periapical radiolucency. At 24 months, the clinical and radiographic success rate was 93% with evidence of continued root growth. Conclusion: Pulp capping with MTA is recommended for teeth with carious pulp exposures specially immature teeth with high potential for healing.

This review deals with the following seven aspects of vertebrate skeletogenic and odontogenic tissues.1The evolutionary sequence in which the tissues appeared amongst the lower craniate taxa.2The topographic association between skeletal (cartilage, bone) and dental (dentine, cement, enamel) tissues in the oldest vertebrates of each major taxon.3The separate developmental origin of the exo- and endoskeletons.4The neural-crest origin of cranial skeletogenic and odontogenic tissues in extant vertebrates.5The neural-crest origin of trunk dermal skeletogenic and odontogenic tissues in extant vertebrates.6The developmental processes that control differentiation of skeletogenic and odontogenic tissues in extant vertebrates.7Maintenance of developmental interactions regulating skeletogenic/odontogenic differentiation across vertebrate taxa. We derive twelve postulates, eight relating to the earliest vertebrate skeletogenic and odontogenic tissues and four relating to the development of these tissues in extant vertebrates and extrapolate the developmental data back to the evolutionary origin of vertebrate skeletogenic and odontogenic tissues. The conclusions that we draw from this analysis are as follows.8The dermal exoskeleton of thelodonts, heterostracans and osteostracans consisted of dentine, attachment tissue (cement or bone), and bone.9Cartilage (unmineralized) can be inferred to have been present in heterostracans and osteostracans, and globular mineralized cartilage was present in Eriptychius, an early Middle Ordovician vertebrate unassigned to any established group, but assumed to be a stem agnathan.10Enamel and possibly also enameloid was present in some early agnathans of uncertain affinities. The majority of dentine tubercles were bare.11The contemporaneous appearance of cellular and acellular bone in heterostracans and osteostracans during the Ordovician provides no clue as to whether one is more primitive than the other.12We interpret aspidin as being developmentally related to the odontogenic attachment tissues, either closer to dentine or a form of cement, rather than as derived from bone.13Dentine is present in the stratigraphically oldest (Cambrian) assumed vertebrate fossils, at present some only included as Problematica, and is cladistically primitive, relative to bone.14The first vertebrate exoskeletal skeletogenic ability was expressed as denticles of dentine.15Dentine, the bone of attachment associated with dentine, the basal bone to which dermal denticles are fused and cartilage of the Ordovician agnathan dermal exoskeleton were all derived from the neural crest and not from mesoderm. Therefore the earliest vertebrate skeletogenic/odontogenic tissues were of neural-crest origin.16Given the separate developmental and evolutionary origin of the cranial exo- and endoskeletons (both derivatives of the cranial neural crest) we conclude that bone (of attachment) was the primary skeletogenic tissue in the exoskeleton (cartilage being secondary), but that uncalcified cartilage was the primary skeletogenic tissue in the endoskeleton (bone – perichondral – being secondary).17Using evidence from developmental biology we conclude that the trunk neural crest of Ordovician agnathans was odontogenic, forming both dentine and bone of attachment of the trunk dermal exoskeleton.18Initiation of differentiation of skeletogenic and odontogenic tissues is controlled epigenetically by one or more epithelial-mesenchymal interactions in epigenetic cascades.19Changes in timing of steps in these epigenetic cascades provides an evolutionary mechanism for altering the types of skeletogenic/odontogenic tissues and/or structures formed.20The appearance of epithelial-mesenchymal interactions and the origin of the skeletogenic/odontogenic neural crest at the outset of vertebrate evolution provided the developmental basis for the evolutionary origin of vertebrate skeletogenic and odontogenic tissues and for the appearance and evolution of the vertebrate skeleton.The evolutionary sequence in which the tissues appeared amongst the lower craniate taxa.The topographic association between skeletal (cartilage, bone) and dental (dentine, cement, enamel) tissues in the oldest vertebrates of each major taxon.The separate developmental origin of the exo- and endoskeletons.The neural-crest origin of cranial skeletogenic and odontogenic tissues in extant vertebrates.The neural-crest origin of trunk dermal skeletogenic and odontogenic tissues in extant vertebrates.The developmental processes that control differentiation of skeletogenic and odontogenic tissues in extant vertebrates.Maintenance of developmental interactions regulating skeletogenic/odontogenic differentiation across vertebrate taxa. We derive twelve postulates, eight relating to the earliest vertebrate skeletogenic and odontogenic tissues and four relating to the development of these tissues in extant vertebrates and extrapolate the developmental data back to the evolutionary origin of vertebrate skeletogenic and odontogenic tissues. The conclusions that we draw from this analysis are as follows.The dermal exoskeleton of thelodonts, heterostracans and osteostracans consisted of dentine, attachment tissue (cement or bone), and bone.Cartilage (unmineralized) can be inferred to have been present in heterostracans and osteostracans, and globular mineralized cartilage was present in Eriptychius, an early Middle Ordovician vertebrate unassigned to any established group, but assumed to be a stem agnathan.Enamel and possibly also enameloid was present in some early agnathans of uncertain affinities. The majority of dentine tubercles were bare.The contemporaneous appearance of cellular and acellular bone in heterostracans and osteostracans during the Ordovician provides no clue as to whether one is more primitive than the other.We interpret aspidin as being developmentally related to the odontogenic attachment tissues, either closer to dentine or a form of cement, rather than as derived from bone.Dentine is present in the stratigraphically oldest (Cambrian) assumed vertebrate fossils, at present some only included as Problematica, and is cladistically primitive, relative to bone.The first vertebrate exoskeletal skeletogenic ability was expressed as denticles of dentine.Dentine, the bone of attachment associated with dentine, the basal bone to which dermal denticles are fused and cartilage of the Ordovician agnathan dermal exoskeleton were all derived from the neural crest and not from mesoderm. Therefore the earliest vertebrate skeletogenic/odontogenic tissues were of neural-crest origin.Given the separate developmental and evolutionary origin of the cranial exo- and endoskeletons (both derivatives of the cranial neural crest) we conclude that bone (of attachment) was the primary skeletogenic tissue in the exoskeleton (cartilage being secondary), but that uncalcified cartilage was the primary skeletogenic tissue in the endoskeleton (bone – perichondral – being secondary).Using evidence from developmental biology we conclude that the trunk neural crest of Ordovician agnathans was odontogenic, forming both dentine and bone of attachment of the trunk dermal exoskeleton.Initiation of differentiation of skeletogenic and odontogenic tissues is controlled epigenetically by one or more epithelial-mesenchymal interactions in epigenetic cascades.Changes in timing of steps in these epigenetic cascades provides an evolutionary mechanism for altering the types of skeletogenic/odontogenic tissues and/or structures formed.The appearance of epithelial-mesenchymal interactions and the origin of the skeletogenic/odontogenic neural crest at the outset of vertebrate evolution provided the developmental basis for the evolutionary origin of vertebrate skeletogenic and odontogenic tissues and for the appearance and evolution of the vertebrate skeleton.

Andreasen JO, Bakland LK, Andreasen FM. Traumatic intrusion of permanent teeth. Part 3. A clinical study of the effect of treatment variables such as treatment delay, method of repositioning, type of splint, length of splinting and antibiotics on 140 teeth. Ó Blackwell Munksgaard, 2006.

The debate about the origin of the vertebrate dentition has been given fresh fuel by new fossil discoveries and developmental studies of extant animals. Odontodes (teeth or tooth-like structures) can be found in two distinct regions, the 'internal' oropharyngeal cavity and the 'external' skin. A recent hypothesis argues that regularly patterned odontodes is a specific oropharyngeal feature, whereas odontodes in the external skeleton lack this organization. However, this argument relies on the skeletal system of modern chondrichthyans (sharks and their relatives), which differ from other gnathostome (jawed vertebrate) groups in not having dermal bones associated with the odontodes. Their external skeleton is also composed of monoodontode 'placoid scales', whereas the scales of most early fossil gnathostomes are polyodontode, i.e. constructed from several odontodes on a shared bony base. Propagation phase contrast X-ray Synchrotron microtomography (PPC-SRmCT) is used to study the polyodontode scales of the early bony fish Andreolepis hedei. The odontodes constructing a single scale are reconstructed in 3D, and a linear and regular growth mechanism similar to that in a gnathostome dentition is confirmed, together with a second, gap-filling growth mechanism. Acanthodian tooth whorls are described, which show that ossification of the whorl base preceded and probably patterned the development of the dental lamina, in contrast to the condition in sharks where the dental lamina develops early and patterns the dentition.The new findings reveal, for the first time, how polyodontode scales grow in 3D in an extinct bony fish. They show that dentition-like odontode patterning occurs on scales and that the primary patterning unit of a tooth whorl may be the bony base rather than the odontodes it carries. These results contradict the hypothesis that oropharyngeal and external odontode skeletons are fundamentally separate and suggest that the importance of dermal bone interactions to odontode patterning has been underestimated.

Essentially we show recent data to shed new light on the thorny controversy of how teeth arose in evolution. Essentially we show (a) how teeth can form equally from any epithelium, be it endoderm, ectoderm or a combination of the two and (b) that the gene expression programs of oral versus pharyngeal teeth are remarkably similar. Classic theories suggest that (i) skin denticles evolved first and odontode-inductive surface ectoderm merged inside the oral cavity to form teeth (the 'outside-in' hypothesis) or that (ii) patterned odontodes evolved first from endoderm deep inside the pharyngeal cavity (the 'inside-out' hypothesis). We propose a new perspective that views odontodes as structures sharing a deep molecular homology, united by sets of co-expressed genes defining a competent thickened epithelium and a collaborative neural crest-derived ectomesenchyme. Simply put, odontodes develop 'inside and out', wherever and whenever these co-expressed gene sets signal to one another. Our perspective complements the classic theories and highlights an agenda for specific experimental manipulations in model and non-model organisms.

Objectives: The purpose of this review, commissioned by the Administration for Children and Families, the Health Resources and Services Administration, the Health Care Financing Administration, and the Department of Agriculture's Food and Nutrition Service, was to update the evidence of the dietary factors that affect dental caries, and subsequently formulate dietary recommendations for preschool children based on principles of cariology. Methods: Literature on the dental caries process, dietary factors affecting dental caries initiation and progression, and nutrition education and counseling were reviewed and synthesized. Dietary guidelines for children at various ages were then constructed based on the review. Results: Dental caries in preschool children is due to a combination of factors, including colonization of teeth with cariogenic bacteria, type of foods and frequency of exposure of these foods to the cariogenic bacteria, and susceptible teeth. Caries risk is greatest if sugars are consumed at high frequency and are in a form that is retained in the mouth for long periods. Sucrose is the most cariogenic sugar because it can form glucan that enables firm bacterial adhesion to teeth and

The frequency of dental abnormalities, such as delayed dental development, microdontia, hypoplasia, agenesis, V-shaped root and shortened root was evaluated in 76 acute lymphoblastic leukemia (ALL) pediatric patients who had been off chemotherapy for 6 months. These children had been subjected to one of the three Brazilian Protocols or the BFM86 Protocol. The patients were divided into three groups: Group I (GI; high risk) treated with one of the three Brazilian Protocols who received high-dose chemotherapy, intensive maintenance and cranial radiotherapy; Group II (GII; low risk) who were also treated with one of the three Brazilian Protocols using low-intensive chemotherapy with no radiotherapy; and Group III (GIII) based on the BFM86 Protocol.

Data from living and extinct faunas of primitive vertebrates imply very different scenarios for the origin and evolution of the dermal and oral skeletal developmental system. A direct reading of the evolutionary relationships of living primitive vertebrates implies that the dermal scales, teeth, and jaws arose synchronously with a cohort of other characters that could be considered unique to jawed vertebrates: the dermoskeleton is primitively composed of numerous scales, each derived from an individual dental papilla; teeth are primitively patterned such that they are replaced in a classical conveyor-belt system. The paleontological record provides a unique but complementary perspective in that: 1) the organisms in which the skeletal system evolved are extinct and we have no recourse but to fossils if we aim to address this problem; 2) extinct organisms can be classified among, and in the same way as, living relatives; 3) a holistic approach to the incorporation of all data provides a more complete perspective on early vertebrate evolution. This combined approach is of no greater significance than in dealing with the origin of the skeleton and, combined with recent discoveries and new phylogenetic analyses, we have been able to test and reject existing hypotheses for the origin of the skeleton and erect a new model in their place.

Introduction: In this research project, we aimed to compare the effectiveness of single (1 deciduous canine) and double (deciduous canine and first molar) extractions in subjects with retained maxillary permanent canines positioned palatally or centrally in the alveolar crest, at risk for root resorption of adjacent permanent teeth. Methods: Subjects at risk for canine impaction or resorptive situations were randomly assigned to 1 of 2 treatment modalities: single extraction (17 patients, 28 canines) or double extraction (20 patients, 37 canines). Thirty-one patients with 53 canines judged to be not at risk constituted the untreated control group. Panoramic radiographs were taken at the initial observation and after 18 months on average. Between-group statistical comparisons were carried out on the changes in canine inclination and sector location (measured on panoramic radiographs) and on the percentages of successful permanent canine eruptions. Results: The double-extraction group showed significant improvements in the success rate and the intrabony position of the permanent canine, in terms of uprighting the canine's long axis with a crown movement in a distal direction. Conclusions: Concomitant deciduous canine and first molar extractions proved to be more effective as a preventive approach to promote eruption of retained maxillary permanent canines positioned palatally or centrally. (Am J Orthod Dentofacial Orthop 2011;139:316-23)

The debate about the origin of the vertebrate dentition has been given fresh fuel by new fossil discoveries and developmental studies of extant animals. Odontodes (teeth or tooth-like structures) can be found in two distinct regions, the 'internal' oropharyngeal cavity and the 'external' skin. A recent hypothesis argues that regularly patterned odontodes is a specific oropharyngeal feature, whereas odontodes in the external skeleton lack this organization. However, this argument relies on the skeletal system of modern chondrichthyans (sharks and their relatives), which differ from other gnathostome (jawed vertebrate) groups in not having dermal bones associated with the odontodes. Their external skeleton is also composed of monoodontode 'placoid scales', whereas the scales of most early fossil gnathostomes are polyodontode, i.e. constructed from several odontodes on a shared bony base. Propagation phase contrast X-ray Synchrotron microtomography (PPC-SRmCT) is used to study the polyodontode scales of the early bony fish Andreolepis hedei. The odontodes constructing a single scale are reconstructed in 3D, and a linear and regular growth mechanism similar to that in a gnathostome dentition is confirmed, together with a second, gap-filling growth mechanism. Acanthodian tooth whorls are described, which show that ossification of the whorl base preceded and probably patterned the development of the dental lamina, in contrast to the condition in sharks where the dental lamina develops early and patterns the dentition.The new findings reveal, for the first time, how polyodontode scales grow in 3D in an extinct bony fish. They show that dentition-like odontode patterning occurs on scales and that the primary patterning unit of a tooth whorl may be the bony base rather than the odontodes it carries. These results contradict the hypothesis that oropharyngeal and external odontode skeletons are fundamentally separate and suggest that the importance of dermal bone interactions to odontode patterning has been underestimated.

Traumatic intrusion of permanent teeth. Part 2. A clinical study of the effect of preinjury and injury factors, such as sex, age, stage of root development, tooth location, and extent of injury including number of intruded teeth on 140 intruded permanent teeth Andreasen JO, Bakland LK, Andreasen FM. Traumatic intrusion of permanent teeth. Part 2. A clinical study of the effect of preinjury and injury factors, such as sex, age, stage of root development, tooth location, and extent of injury including number of intruded teeth on 140 intruded permanent teeth.

The study was undertaken to evaluate mineral trioxide aggregate (MTA) clinically and radiographically as a pulpotomy agent in immature permanent teeth whose pulps were exposed by a complicated crown fracture. Thirty incisors with exposed pulps in twenty-nine patients were examined for this retrospective study. According to exclusion criteria, only twenty-seven teeth were selected. Each tooth was treated with partial pulpotomy and the wounded pulp was covered with mineral trioxide aggregate. The children were recalled for clinical and radiographic evaluation at 3 months, 6 months, at approximately 12 months and 36 months. Out of 27 cases, 22 were categorized as 'healed' and 1 as 'healing'. The remaining 4 ones highlighted persistent disease and needed further endodontic treatment. MTA partial pulpotomy is an effective treatment in maintaining pulpal vitality and allowing physiological root development (apexogenesis).

Gene expression and knock-out studies provide considerable information about the genetic mechanisms required for tooth organogenesis. Quantitative genetic studies of normal phenotypic variation are complementary to these developmental studies and may help elucidate the genes and mechanisms that contribute to the normal population-level phenotypic variation upon which selection acts. Here we present the first quantitative genetic analysis of molar cusp positioning in mammals. We analyzed quantitative measures of molar cusp position in a captive pedigreed baboon breeding colony housed at the Southwest National Primate Research Center in San Antonio, Texas. Our results reveal complete pleiotropy between antimeric pairs of traits -i.e., they are influenced by the same gene or suite of genes. Mandibular morphological homologues in the molar series also exhibit complete pleiotropy. In contrast, morphological homologues in maxillary molar series appear to be influenced by partial, incomplete pleiotropic effects. Variation in the mandibular mesial and distal molar loph orientation on the same molar crown is estimated to be genetically independent, whereas the maxillary molar mesial and distal loph orientation is estimated to have partially overlapping genetic affects. The differences between the maxillary and mandibular molar patterning, and the degree of genetic independence found between lophs on the same molar crown, may be indicative of previously unrecognized levels of modularity in the primate dentition.

Intake of excess amounts of fluoride during tooth development cause enamel fluorosis, a developmental disturbance that makes enamel more porous. In mild fluorosis, there are white opaque striations across the enamel surface, whereas in more severe cases, the porous regions increase in size, with enamel pitting, and secondary discoloration of the enamel surface. The effects of fluoride on enamel formation suggest that fluoride affects the enamelforming cells, the ameloblasts. Studies investigating the effects of fluoride on ameloblasts and the mechanisms of fluorosis are based on in vitro cultures as well as animal models. The use of these model systems requires a biologically relevant fluoride dose, and must be carefully interpreted in relation to human tooth formation. Based on these studies, we propose that fluoride can directly affect the ameloblasts, particularly at high fluoride levels, while at lower fluoride levels, the ameloblasts may respond to local effects of fluoride on the mineralizing matrix. A new working model is presented, focused on the assumption that fluoride increases the rate of mineral formation, resulting in a greater release of protons into the forming enamel matrix.

Classically the oral dentition with teeth regulated into a successional iterative order was thought to have evolved from the superficial skin denticles migrating into the mouth at the stage when jaws evolved. The canonical view is that the initiation of a pattern order for teeth at the mouth margin required development of a sub-epithelial, permanent dental lamina. This provided regulated tooth production in advance of functional need, as exemplified by the Chondrichthyes. It had been assumed that teeth in the Osteichthyes form in this way as in tetrapods. However, this has been shown not to be true for many osteichthyan fish where a dental lamina of this kind does not form, but teeth are regularly patterned and replaced. We question the evolutionary origin of pattern information for the dentition driven by new morphological data on spatial initiation of skin denticles in the catshark. We review recent gene expression data for spatio-temporal order of tooth initiation for Scyliorhinus canicula, selected teleosts in both oral and pharyngeal dentitions, and Neoceratodus forsteri. Although denticles in the chondrichthyan skin appear not to follow a strict pattern order in space and time, tooth replacement in a functional system occurs with precise timing and spatial order. We suggest that the patterning mechanism observed for the oral and pharyngeal dentition is unique to the vertebrate oro-pharynx and independent of the skin system. Therefore, co-option of a successional iterative pattern occurred in evolution not from the skin but from mechanisms existing in the oro-pharynx of now extinct agnathans.

Mammalian tooth development is largely dependent on sequential and reciprocal epithelial-mesenchymal interactions. These processes involve a series of inductive and permissive interactions that result in the determination, differentiation, and organization of odontogenic tissues. Multiple signaling molecules, including BMPs, FGFs, Shh, and Wnt proteins, have been implicated in mediating these tissue interactions. Transcription factors participate in epithelial-mesenchymal interactions via linking the signaling loops between tissue layers by responding to inductive signals and regulating the expression of other signaling molecules. Adult stem cells are highly plastic and multipotent. These cells including dental pulp stem cells and bone marrow stromal cells could be reprogrammed into odontogenic fate and participated in tooth formation. Recent progress in the studies of molecular basis of tooth development, adult stem cell biology, and regeneration will provide fundamental knowledge for the realization of human tooth regeneration in the near future.

Introduction: The present study aimed at developing an experimental model in rat molars for evaluating treatment strategies in necrotic immature teeth. Methods: To define the periods to be adopted in the experimental procedures and to confirm induction of periapical lesions and interruption of root embryogenesis, the left lower first molars of 4-weeks-old Wistar rats underwent pulpectomy and were left open to the oral environment. Comparisons with the right lower first molars (vital teeth) were performed in animals with ages of 7, 10, 13, and 16 weeks. In another group of animals the teeth were left open for 3 weeks, and then interventions for disinfection including the use of an antibiotic paste were carried out. Root formation was then assessed after 3 and 6 weeks on the basis of radiographic and histologic evaluation. Results: Vital teeth showed increase of root length and hard tissue thickness throughout the experimental periods. On the other hand, induction of necrosis arrested root formation. Teeth subjected to disinfection with sodium hypochlorite associated with the triple antibiotic paste showed significant reduction of periapical lesions, gain in root length, and increased wall thickness compared with the control (P < .05). Conclusions: The root canal disinfection protocol used was able to reduce periapical lesion size and improve root development. The experimental model presented should contribute to studies that aim at improving therapeutic strategies for necrotic immature teeth by using a rat model. (J Endod 2011;37:1069-1073

RESUMEN: La anestesia local odontológica es un procedimiento de rutina en la práctica odontológica pediátrica que, tal como otros sucesos, podría generar anomalías en el desarrollo dental, considerando la susceptibilidad de los gérmenes dentales en desarrollo; por lo anterior consideramos necesario determinar la existencia de asociación entre anomalías del desarrollo dental y el uso de técnicas anestésicas. Para esto se diseñó un estudio descriptivo basado en búsqueda sistemática de literatura en las bases de datos: Scopus, MEDLINE, Web of Science Core Collection, ProQuest Central, Korean Journal Database y SciELO, utilizando combinación de términos MeSH: ("odontoblasts" OR "ameloblasts" OR "odontogenesis" OR "amelogenesis" OR "dentinogenesis" OR "odontodysplasia" OR "dental enamel hypoplasia" OR "dental sac" OR "dental papilla" OR "enamel organ") AND ("anesthesia" OR "local anesthesia" OR "nerve block" OR "dental anesthesia"). De un total de 96 artículos, se incluyeron para revisión 5 artículos relacionados con los objetivos de esta revisión, excluyéndose las coincidencias. La evidencia presente en la literatura es contradictoria. Existen múltiples diferencias entre los estudios analizados, las que podrían deberse a las técnicas anestésicas involucradas, tipo de anestésico, la no consideración de otros posibles agentes causales (síndromes) o la terapia odontológica. No puede ser determinado una relación entre estos dos aspectos.

PALABRAS CLAVE: anestesia dental, desarrollo dental, anomalías.

ABSTRACT: The dental local anesthesia is a routine procedure in pediatric dental practice that, as other events could generate abnormalities in dental development, considering the susceptibility of developing tooth germs. From the foregoing it necessary to determine the existence of association between disorders of tooth development and use of anesthetic techniques. A descriptive study based on systematic literature review in databases: Scopus, MEDLINE, Web of Science Core Collection, ProQuest Central, Korean Journal Database and SciELO data was designed, using the following combination of MeSH terms ("odontoblasts" OR "ameloblasts" OR "odontogenesis" OR "amelogenesis" OR "dentinogenesis" OR "odontodysplasia" OR "dental enamel hypoplasia" OR "dental sac" OR "dental papilla" OR "enamel organ") AND ("anesthesia" OR "local anesthesia "OR" nerve block "OR" dental anesthesia"). A total of 96 articles, were included for review a total of 5 articles related to the objectives of this review, excluding the matches. The present evidence in the literature is contradictory. There are many differences between the studies analyzed, which could be due to the anesthetic techniques involved, type of anesthetic, other possible causative agents (syndromes) or dental treatment are not included. It can not be determined a relationship between these two aspects.

KEY WORDS: dental anesthesia, dental development, abnormalities.

Purpose: The purpose of this study was to compare mineral trioxide aggregate (MTA) with calcium hydroxide (Ca(OH)2) clinically and radiographically as a pulpotomy agent in immature permanent teeth (apexogenesis). Methods: Fifteen children, each with at least 2 immature permanent teeth requiring pulp- otomy (apexogenesis), were selected for this study. All selected teeth were evenly divided into 2 test groups. In

Adenomatoid odontogenic tumor (AOT) is an uncommon benign odontogenic tumor representing approximately 3% of all odontogenic tumors. In about 74% of cases, this tumor is associated with an impacted tooth, of which two-third of the cases is in relation to the maxillary anterior tooth. Rarely, this lesion can also occur in the absence of an impacted tooth within jaw bones. These variants of AOT are referred as extra follicular AOT. As the clinical picture and radiographic picture varies from the conventional AOT, the diagnosis is often challenging. Here, we report a case of extra follicular AOT of the anterior maxilla in a 22-year-old female patient.

External root resorption (ERR) is a serious complication after replantation, and its progressive inflammatory and replacement forms are significant causes of tooth loss. This retrospective study aimed to evaluate the factors related to the occurrence of inflammatory ERR (IERR) and replacement ERR (RERR) shortly after permanent tooth replantation in patients treated at the Dental Trauma Clinic at the School of Dentistry, Federal University of Minas Gerais, Belo Horizonte, Brazil. Case records and radiographs of 165 patients were evaluated for the presence, type, and extension of ERR and its association with age and factors related to the management and acute treatment of the avulsed tooth by using the logistic regression model. The patient&#39;s age at the moment of trauma had a marked effect on the ERR prevalence and extension. The patients older than 16 years at the moment of trauma had less chance of developing IERR and RERR (77% and 87%, respectively) before the pulp extirpation,...

Most actinopterygians replace their teeth continuously throughout life. To address the question of where and how replacement teeth form in actinopterygians, it is advisable to investigate well-chosen representatives within the lineage. The African bichir, Polypterus senegalus, belongs to the earliest diverged group of the actinopterygian lineage with currently living representatives. Its well characterized dentition, together with its phylogenetic position, make this species an attractive model to answer following questions: (1) when and where does the replacement tooth form and how is it connected with the dental organ of the predecessor, and (2) is there any evidence for the presence of epithelial stem cells, hypothesized to play a role in replacement? Serial sections show that one tooth family can contain up to three members, which are all interconnected by dental epithelium. Replacement teeth develop without the presence of a successional dental lamina. We propose that this is the plesiomorphic condition for tooth replacement in actinopterygians. BrdU pulse-chase experiments reveal cells in the outer and middle dental epithelium, proliferating at the time of initiation of a new replacement tooth. It is tempting to assume that these cell layers provide a stem cell niche. The observed absence of label-retaining cells after long chase times (up to 8 weeks) is held against the light of divergent views on cell cycling properties of stem cells. At present, our data do not support, neither reject, the hypothesis on involvement of epithelial stem cells within the process of continuous tooth replacement.

This article focuses on the biological characterization and discussion of the potential application of oral-derived adult stem cells for craniofacial tissue engineering applications. The authors reviewed experimental (in vitro and in vivo) and clinical reports regarding the isolation, characterization, modulation, and translational clinical application of human precursor cell populations derived from postnatal dental tissues. Five different human dental stem/progenitor cell populations have been isolated and characterized. These postnatal populations present mesenchymal stem cell-like characteristics and enjoy forceful capabilities regarding the differentiation into odontogenic/osteogenic lineages, supporting evidence--in preclinical and clinical trials--for the regeneration of oral/dental tissues.

Ectodermal dysplasia syndromes affect the development of several organs, including hair, teeth, and glands. The recent cloning of two genes responsible for these syndromes has led to the identification of a novel TNF family ligand, ectodysplasin, and TNF receptor, edar. This has indicated a developmental regulatory role for TNFs for the first time. Our in situ hybridization analysis of the expression of ectodysplasin (encoded by the Tabby gene) and edar (encoded by the downless gene) during mouse tooth morphogenesis showed that they are expressed in complementary patterns exclusively in ectodermal tissue layer. Edar was expressed reiteratively in signaling centers regulating key steps in morphogenesis. The analysis of the effects of eight signaling molecules in the TGF␤, FGF, Hh, Wnt, and EGF families in tooth explant cultures revealed that the expression of edar was induced by activin␤A, whereas Wnt6 induced ectodysplasin expression. Moreover, ectodysplasin expression was downregulated in branchial arch epithelium and in tooth germs of Lef1 mutant mice, suggesting that signaling by ectodysplasin is regulated by LEF-1-mediated Wnt signals. The analysis of the signaling centers in tooth germs of Tabby mice (ectodysplasin null mutants) indicated that in the absence of ectodysplasin the signaling centers were small. However, no downstream targets of ectodysplasin signaling were identified among several genes expressed in the signaling centers. We conclude that ectodysplasin functions as a planar signal between ectodermal compartments and regulates the function, but not the induction, of epithelial signaling centers. This TNF signaling is tightly associated with epithelial-mesenchymal interactions and with other signaling pathways regulating organogenesis. We suggest that activin signaling from mesenchyme induces the expression of the TNF receptor edar in the epithelial signaling centers, thus making them responsive to Wnt-induced ectodysplasin from the nearby ectoderm. This is the first demonstration of integration of the Wnt, activin, and TNF signaling pathways.

Biomimicry has been introduced as a term for innovations inspired by nature [1]. Such innovations may appear in almost every part of modern society. This review on the effects of enamel matrix proteins on the formation of cementum and the development of emdogain for regeneration of periodontal tissues lost due to periodontitis shows an example of biomimicry in dentistry. Findings from clinical and laboratory investigations are summarized and the biological basis for enamel matrix-induced periodontal regeneration is discussed.

A variety of quantitative measures of distance and similarity have been used in physical anthropology, often without sufficient prior testing of their usefulness and understanding of their meaning. A variety of such coefficients were compared by applying them to a n odontometric sample. It was found that Penrose's size-shape dichotomy extends not only to his coefficients but to all other similarity measures as well, such as the coefficient of racial likeness, generalized distance, canonical variates, and &-mode correlation. Only size differences were detected by the C.R.L., Penrose's size distance, D2, and canonical variates, and as a result these methods failed to produce a n accurate classification. Penrose's shape distance and &-mode correlation coefficients produced better results due to their determination of similarity on the basis of more important shape and morphological differences. The D2 and canonical variates methods were converted to shape measures through &-mode standardization of the raw data, whereupon they also produced more meaningful results. 743 AM. J. P H Y S . ANTHROP., 38: 743-754.

Mesenchymal stem cells (MSCs) have been isolated from the pulp tissue of permanent teeth (dental pulp stem cells or DPSCs) and deciduous teeth (stem cells from human exfoliated deciduous teeth). We recently discovered another type of MSCs in the apical papilla of human immature permanent teeth termed stem cells from the apical papilla (SCAP). Here, we further characterized the apical papilla tissue and stem cell properties of SCAP using histologic, immunohistochemical, and immunocytofluorescent analyses. We found that the apical papilla is distinctive to the pulp in terms of containing less cellular and vascular components than those in the pulp. Cells in the apical papilla proliferated 2- to 3-fold greater than those in the pulp in organ cultures. Both SCAP and DPSCs were as potent in osteo/dentinogenic differentiation as MSCs from bone marrows, whereas they were weaker in adipogenic potential. The immunophenotype of SCAP is similar to that of DPSCs on the osteo/dentinogenic and gr...

X-linked hypohidrotic ectodermal dysplasia (XLHED, OMIM 305100) is a rare congenital disorder that results in the defective development of teeth, hair, nails, and eccrine sweat glands. Previous studies found that mutations in the ectodysplasin A (EDA) gene are associated with XLHED. In the present study, we investigated four Chinese families suffering from classical XLHED and investigated two additional families segregating hypodontia in an X-linked recessive manner. Mutations were characterized respectively in the EDA gene in all families, and five of these mutations were found to be novel. Among these mutations, five were missense (c.200A>T, c.463C>T, c.758T>C, c.926T>G, and c.491A>C) and located in the functional domain of EDA, and one was a splice donor site mutation in intron 5 (c.IVS5 + 1G>A), which may result in an alternative transcript derived from a new cryptic splice site. Our data further confirm that EDA mutations could cause both XLHED and isolated hypodontia and provide evidence that EDA is a strong candidate gene for tooth genesis.