-
International Journal of Paediatric... May 2004Children who present with a posterior cross-bite in the primary dentition may be predisposed to long-term detrimental consequences if the condition is left untreated.... (Review)
Review
INTRODUCTION
Children who present with a posterior cross-bite in the primary dentition may be predisposed to long-term detrimental consequences if the condition is left untreated. Controversy exists in the literature as to the most appropriate time to treat this condition.
OBJECTIVES
The aim of this review is to evaluate the need for correcting posterior cross-bites in the primary dentition based on the current understanding of the aetiology, likelihood of self-correction, and consequences of various forms of this malocclusion persisting into the mixed and permanent dentitions. A review of the reported treatment options for management of this condition is also presented.
METHODS
Literature pertaining to the epidemiology and management of posterior cross-bites in the primary dentition are reviewed.
CONCLUSION
Posterior cross-bites in the primary dentition are relatively common and their causes are numerous. Because a significant proportion of posterior cross-bites self-correct beyond the primary dentition, routine correction in the primary dentition phase cannot be advocated. A unilateral posterior cross-bite as a result of a functional displacement of the mandible is one of the few malocclusions which should be considered for correction in the primary dentition. Further research is needed in the management of this condition.
Topics: Child; Child, Preschool; Dentition, Mixed; Humans; Malocclusion; Orthodontic Appliances; Tooth, Deciduous; Treatment Outcome
PubMed: 15139950
DOI: 10.1111/j.1365-263X.2004.00546.x -
Scientific Reports Jan 2021The evolution of gigantism in extinct otodontid sharks was paralleled by a series of drastic modifications in their dentition including widening of the crowns, loss of...
The evolution of gigantism in extinct otodontid sharks was paralleled by a series of drastic modifications in their dentition including widening of the crowns, loss of lateral cusplets, and acquisition of serrated cutting edges. These traits have generally been interpreted as key functional features that enabled the transition from piscivory to more energetic diets based on marine mammals, ultimately leading to the evolution of titanic body sizes in the most recent forms (including the emblematic Otodus megalodon). To investigate this hypothesis, we evaluate the biomechanics of the anterior, lateral, and posterior teeth of five otodontid species under different loading conditions by using two-dimensional finite element analysis. Stress distribution patterns are remarkably similar among all models under puncture and draw (i.e., when subjected to vertical and lateral forces, respectively). Contrary to expectation, higher average stress values are detected under both loading scenarios in more recent species. Altogether, this suggests little correlation between tooth morphology and key aspects of biomechanical behaviour in otodontids, making it difficult to frame the morphological trend of their dentitions within an adaptive scenario. We propose that this pattern most likely emerged as a non-functional by-product of heterochronic processes driven by selection towards larger body sizes.
Topics: Animals; Biological Evolution; Biomechanical Phenomena; Body Size; Dentition; Finite Element Analysis; Fossils; Sharks; Tooth
PubMed: 33441828
DOI: 10.1038/s41598-020-80323-z -
Science (New York, N.Y.) Jul 2020The dentitions of extant fishes and land vertebrates vary in both pattern and type of tooth replacement. It has been argued that the common ancestral condition likely...
The dentitions of extant fishes and land vertebrates vary in both pattern and type of tooth replacement. It has been argued that the common ancestral condition likely resembles the nonmarginal, radially arranged tooth files of arthrodires, an early group of armoured fishes. We used synchrotron microtomography to describe the fossil dentitions of so-called acanthothoracids, the most phylogenetically basal jawed vertebrates with teeth, belonging to the genera , , and (from the Early Devonian of the Czech Republic). Their dentitions differ fundamentally from those of arthrodires; they are marginal, carried by a cheekbone or a series of short dermal bones along the jaw edges, and teeth are added lingually as is the case in many chondrichthyans (cartilaginous fishes) and osteichthyans (bony fishes and tetrapods). We propose these characteristics as ancestral for all jawed vertebrates.
Topics: Animals; Biological Evolution; Czech Republic; Dentition; Electron Microscope Tomography; Fossils; Jaw; Phylogeny; Synchrotrons; Tooth; Vertebrates
PubMed: 32647004
DOI: 10.1126/science.aaz9431 -
Integrative and Comparative Biology Sep 2020The Holocephali is a major group of chondrichthyan fishes, the sister taxon to the sharks and rays (Elasmobranchii). However, the dentition of extant holocephalans is...
The Holocephali is a major group of chondrichthyan fishes, the sister taxon to the sharks and rays (Elasmobranchii). However, the dentition of extant holocephalans is very different from that of the elasmobranchs, lacking individual tooth renewal, but comprising dental plates made entirely of self-renewing dentine. This renewal of all tissues occurs at the postero-lingual plate surface, as a function of their statodont condition. The fossil record of the holocephalans illuminates multiple different trends in the dentition, including shark-like teeth through to those with dentitions completely lacking individual teeth. Different taxa illustrate developmental retention of teeth but with fusion in their serial development. Dentine of different varieties comprises these teeth and composite dental plates, whose histology includes vascularized tubes within coronal dentine, merging with basal trabecular dentine. In this coronal vascularized dentine, extensive hypermineralization forms a wear resistant tissue transformed into a variety of morphologies. Through evolution, hypermineralized dentine becomes enclosed within the trabecular dentine, and specialized by reduction into specific zones within a composite dental plate, with these increasing in morphological disparity, all reflecting loss of defined teeth but retention of dentine production from the inherited developmental package.
Topics: Animals; Biological Evolution; Calcification, Physiologic; Dentition; Fishes; Tooth
PubMed: 32617556
DOI: 10.1093/icb/icaa093 -
Cladistics : the International Journal... Dec 2023Mesotheriidae (Panperissodactyla, Notoungulata) are an extinct clade (early Oligocene-Pleistocene) of small to medium-sized herbivorous mammals that were widely...
Mesotheriidae (Panperissodactyla, Notoungulata) are an extinct clade (early Oligocene-Pleistocene) of small to medium-sized herbivorous mammals that were widely distributed in South America. Although two subfamilies traditionally have been recognized (Trachytheriinae and Mesotheriinae), recent cladistic analyses based on discrete characters have indicated that "Trachytheriinae" is a paraphyletic assemblage. Given the availability of a large number of specimens and the fact that dental characters are the most common characters used in mesotheriid phylogenies, we performed specimen-level cladistic analyses combining discrete, continuous and geometric morphometrics-based dental characters. The aim was to: (1) include new scored morphological characters to solve the phylogenetic relationships of Mesotheriidae; (2) compare the results of the upper and lower dentition analyses as different character partitions and in combination, to establish phylogenetic hypotheses; and (3) trace the evolution of dental traits. Phylogenetic analyses employing characters of associated upper and lower dentitions recovered one most parsimonious tree with Archaeohyracidae (outgroup) as the sister group of Pan-Mesotheriidae (= Mesotheriidae; converted clade name), this latter composed of trachytheriines (stem-mesotheriine) + Mesotheriinae (converted clade name). Within Mesotheriinae, we recovered two main lineages phylogenetically defined here as Bolivarini and Pampaini (new clade names). Analyses of isolated upper and lower dentition sub-datasets each resulted in one most parsimonious tree congruent with the associated dentition. Our study emphasizes the use of geometric morphometrics characters to resolve additional clades in phylogenetic analyses, provides information on the evolution of size and morphology of teeth, and exposes specimen assignment issues at a taxonomic level. The integration of osteological characters might be crucial to further understanding the evolution of Mesotheriidae.
Topics: Animals; Phylogeny; Dentition; Mammals; Eutheria; Tooth
PubMed: 37490279
DOI: 10.1111/cla.12554 -
Integrative and Comparative Biology Sep 2020Vertebrates interact directly with food items through their dentition, and these interactions with trophic resources could often feedback to influence tooth structure.... (Review)
Review
Vertebrates interact directly with food items through their dentition, and these interactions with trophic resources could often feedback to influence tooth structure. Although dentitions are often considered to be a fixed phenotype, there is the potential for environmentally induced phenotypic plasticity in teeth to extensively influence their diversity. Here, we review the literature concerning phenotypic plasticity of vertebrate teeth. Even though only a few taxonomically disparate studies have focused on phenotypic plasticity in teeth, there are a number of ways teeth can change their size, shape, or patterns of replacement as a response to the environment. Elucidating the underlying physiological, developmental, and genetic mechanisms that generate phenotypic plasticity can clarify its potential role in the evolution of dental phenotypes.
Topics: Adaptation, Physiological; Animals; Dentition; Tooth; Vertebrates
PubMed: 32544244
DOI: 10.1093/icb/icaa077 -
British Dental Journal Nov 2020
Topics: Dentition
PubMed: 33247236
DOI: 10.1038/s41415-020-2419-4 -
Zhonghua Kou Qiang Yi Xue Za Zhi =... Sep 2021To record occlusal contact of primary dentition at maximal intercuspal position in children with individual normal occlusion. A total of 57 children were recruited...
To record occlusal contact of primary dentition at maximal intercuspal position in children with individual normal occlusion. A total of 57 children were recruited from patients of the Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology. Inclusion criteria were that the subjects were 3-5 years old with no visually detectable caries or pupal and periapical diseases, had complete primary dentition, had individual normal occlusion, had normal function of craniofacial system, were medically healthy, could cooperate with sampling and had obtained written informed consent from the parents or guardians. Finally, forty-seven children aged 3 to 5 years old were enrolled, including 24 males and 23 females. The age, height and weight of all subjects were (4.1±0.7) years old (ranging 3.0-5.8 years old), (103.7±7.2) cm (ranging 90-120 cm) and (17.1±2.5) kg (ranging 12.5-22.5 kg), respectively. Occlusal abilities such as occlusal contact area, average bite pressure, maximum bite pressure, maximum bite force and occlusal balance were measured with Dental Prescale Ⅱ system. Maximum bite force and occlusal contact area at intercuspal position in children with primary dentition were (567.40±223.84) N (ranging 226.7-1 154.6 N) and (18.56±6.54) mm (ranging 8.4-41.2 mm), respectively. There was a significantly strong correlation between maximum bite force and occlusal contact area (=0.954, <0.01). Height and weight of children were also positively correlated with their maximum bite force (=0.397, =0.022 and =0.453, =0.008, respectively). Maximum occlusal bite force and contact occlusal area of boys [(651.80±224.34) N and (20.77±6.97) mm] were significantly higher and larger than those of girls [(479.34±190.45) N and (16.25±5.27) mm] (<0.05). Thirty-two of all 47 children had one occlusal contact point with maximum bite pressure, mostly locating within the primary molar region. Bite forces of anterior and posterior teeth of primary dentition were (124.12±56.99) N and (450.11±205.09) N, respectively, about (21.82±11.40)% and (71.80±21.35)% of maximum bite force of the whole primary dentition. All of the occlusal balance points located in posterior teeth regions. Occlusal contacts were observed at both anterior and posterior teeth of primary dentition with individual normal occlusion. There was a great variation of maximum bite forces of primary dentitions at intercuspal position of children with individual normal occlusion. Maximum bite force of primary dentition was significantly correlated with occlusal contact area, height and weight of children. Occlusal contact points with maximum bite pressure and occlusal bite balance points of primary dentitions mostly located in primary molar regions.
Topics: Bite Force; Child; Child, Preschool; Dental Occlusion; Female; Humans; Male; Molar; Tooth, Deciduous
PubMed: 34496535
DOI: 10.3760/cma.j.cn112144-20210514-00237 -
BMC Oral Health Aug 2016Mixed dentition space analysis forms an important part of orthodontic diagnosis and treatment planning. Regression equations are widely used for mixed dentition analysis...
BACKGROUND
Mixed dentition space analysis forms an important part of orthodontic diagnosis and treatment planning. Regression equations are widely used for mixed dentition analysis which can vary among races. This study aimed to find out the new regression equation in estimating the size of unerupted canines and premolars for Nepalese Brahmins/Chhetris.
METHODS
Hundred Nepalese Brahmins/Chhetris (50 males and 50 females) who met our criteria were selected among the patients attending to the Orthodontic Out-Patient Department, Institute of Medicine, Kathmandu. The mesiodistal widths of all mandibular permanent incisors; maxillary and mandibular canines and premolars were measured and analyzed. The results were also compared with predicted values from the Moyers and the Tanaka and Johnston methods. Correlation and linear regression analyses were performed between the predicted and actual tooth sizes for Nepalese Brahmins/Chhetris and standard regression equations were developed.
RESULTS
No significant differences were observed when the sum of canine and premolars of one quadrant is compared between sides and sex. Significant and high positive correlations were found between the mandibular incisors and the combined mesiodistal widths of the canines and premolars for the maxillary (r = 0.72) and mandibular (r = 0.73) segments. Significant differences were observed between the measured values from this study and from Moyers (50 % and 75 % probability) and Tanaka-Johnston methods.
CONCLUSIONS
The equations and charts commonly used for North American children (50(th) or 75(th) percentile) did not accurately predict for our sample, so new regression equations and tables were developed for Nepalese Brahmins/Chhetris children.
Topics: Bicuspid; Cuspid; Dentition, Mixed; Female; Humans; Incisor; Male; Odontometry; Regression Analysis; Tooth, Unerupted
PubMed: 27484030
DOI: 10.1186/s12903-016-0265-1 -
Microbiome Apr 2018The present study aimed to identify patterns and processes in acquisition of oral bacteria and to characterize the microbiota of different dentition states and habitats....
METHODS
The present study aimed to identify patterns and processes in acquisition of oral bacteria and to characterize the microbiota of different dentition states and habitats. Mucosal, salivary, supragingival, and subgingival biofilm samples were collected from orally and systemically healthy children and mother-child dyads in predentate, primary, mixed, and permanent dentitions. 16S rRNA gene sequences were compared to the Human Oral Microbiome Database (HOMD). Functional potential was inferred using PICRUSt.
RESULTS
Unweighted and weighted UniFrac distances were significantly smaller between each mother-predentate dyad than infant-unrelated female dyads. Predentate children shared a median of 85% of species-level operational taxonomic units (s-OTUs) and 100% of core s-OTUs with their mothers. Maternal smoking, but not gender, mode of delivery, feeding habits, or type of food discriminated between predentate microbial profiles. The primary dentition demonstrated expanded community membership, structure, and function when compared to the predentate stage, as well as significantly lower similarity between mother-child dyads. The primary dentition also included 85% of predentate core s-OTUs. Subsequent dentitions exhibited over 90% similarity to the primary dentition in phylogenetic and functional structure. Species from the predentate mucosa as well as new microbial assemblages were identified in the primary supragingival and subgingival microbiomes. All individuals shared 65% of species between supragingival and subgingival habitats; however, the salivary microbiome exhibited less than 35% similarity to either habitat.
CONCLUSIONS
Within the limitations of a cross-sectional study design, we identified two definitive stages in oral bacterial colonization: an early predentate imprinting and a second wave with the eruption of primary teeth. Bacterial acquisition in the oral microbiome is influenced by the maternal microbiome. Personalization begins with the eruption of primary teeth; however, this is limited to phylogeny; functionally, individuals exhibit few differences, suggesting that microbial assembly may follow a defined schematic that is driven by the functional requirements of the ecosystem. This early microbiome forms the foundation upon which newer communities develop as more colonization niches emerge, and expansion of biodiversity is attributable to both introduction of new species and increase in abundance of predentate organisms.
Topics: Biodiversity; Cross-Sectional Studies; Dentition; Gingiva; Humans; Metagenome; Metagenomics; Microbiota; Mouth; Phylogeny; RNA, Ribosomal, 16S; Saliva
PubMed: 29631628
DOI: 10.1186/s40168-018-0443-2