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Dental Press Journal of Orthodontics 2022To determine the discrepancy of crown-root morphology of anterior teeth, using cone-beam computed tomography (CBCT), and to provide a guidance for proper torque...
OBJECTIVE
To determine the discrepancy of crown-root morphology of anterior teeth, using cone-beam computed tomography (CBCT), and to provide a guidance for proper torque expression.
METHODS
A total of eligible 200 CBCT were imported into Invivo v. 5.4 software, to obtain the middle labio-lingual sections of anterior teeth. AutoCAD 2007 software was applied to measure the crown-root angulation (Collum angle) and the angle formed by a tangent to the center of the labial surface and the long axis of the crown (labial surface angle). SPSS 18.0 was used for statistical comparisons of the two measurements, at the level of p< 0.05, and the Pearson correlation analysis was applied to investigate the association between the two measurements.
RESULTS
The value of Collum angle in maxillary central incisor was close to 0°. Significantly negative Collum angle in lateral incisors and maxillary canine, and positive value in mandibular canine were detected (p < 0.001). The labial surface angle in canine was significantly greater than the intra-arch incisors (p< 0.001), and no significant difference was detected between the central and lateral incisors (p > 0.05). Notably, there was also a significant positive correlation between the two measurements.
CONCLUSIONS
The crown-root angulations were greatly different among anterior teeth. Accompanying the obvious crown-root angulations, the canines both in maxillary and mandibular arches presented considerable labial surface curvatures. Hence, equivalent deviation during bracket bonding might cause greater torque expression error and increase the risk of alveolar fenestration and dehiscence.
Topics: Cone-Beam Computed Tomography; Crowns; Incisor; Maxilla; Tooth Crown
PubMed: 35544841
DOI: 10.1590/2177-6709.27.1.e222079.oar -
The Bulletin of Tokyo Dental College 2018The purpose of the present study was to investigate change in the size of the jaw and deciduous teeth in Japanese children over the past 40 years by performing... (Comparative Study)
Comparative Study
The purpose of the present study was to investigate change in the size of the jaw and deciduous teeth in Japanese children over the past 40 years by performing measurements on plaster models of the dental arch obtained from children born between 2007 and 2009 (2000s group) and children born between 1968 and 1974 (70s) group. A total of 61 children were enrolled in the 2000s group, comprising 25 boys (average age, 4 years 5 months) and 36 girls (average age, 4 years 4 months), and 93 children in the 70s group, comprising 45 boys (4 years 6 months) and 48 girls (4 years 4 months). The mesiodistal width of the crown, dental arch width, dental arch length, dental arch height, and available arch length in these groups were measured using a 3D measurement system and the sums of the mesiodistal width of the crown and tooth size-arch length discrepancies calculated. The results of the two groups were statistically compared and the following conclusions reached: the size of deciduous teeth has not changed statistically over the last 40 years; the size of the dental arch has decreased in boys (p<0.01), while remaining approximately the same in girls; and the tooth size-arch length discrepancy has decreased, especially in boys (p<0.01). These results indicate that the interdental spaces of the deciduous dentition have decreased, increasing the risk of crowding in Japanese children.
Topics: Asian People; Child, Preschool; Dental Arch; Female; Humans; Japan; Male; Models, Dental; Tooth Crown; Tooth, Deciduous
PubMed: 30224611
DOI: 10.2209/tdcpublication.2017-0033 -
BioMed Research International 2022To analyze the width and height ratios of maxillary anterior teeth at different crown levels through photographs, 3D, and plaster dental model techniques in a subset of...
OBJECTIVE
To analyze the width and height ratios of maxillary anterior teeth at different crown levels through photographs, 3D, and plaster dental model techniques in a subset of the Pakistani population. . This clinical study consisted of 230 participants. The maxillary impression, standardized photographs, and models were constructed for crown width and height analysis. The SPSS version 25 was used for statistical analysis. Descriptive statistics were carried out for mean, standard deviation, and percentage calculation of teeth width and height, gender, and age of participants. Paired -test analysis was carried out to compare the dependent variables (teeth size, width, and height ratios) with independent variables (techniques applied, side disparity). A value of ≤ 0.05 was considered statistically significant.
RESULTS
The mean width and height of maxillary anterior teeth obtained through photographs, 3D, and plater models were statistically different. The 3D dental model analysis showed reliable and accurate results. The mean width and height ratio of teeth were different on both sides of the arch. There was a significant difference ( = 0.001) in crown width-height ratios at different crown levels.
CONCLUSION
The width and height ratios in the studied population were different at various crown levels. The dimensions of teeth varied from the incisal to the cervical part of the crown. Hence, rather than relying on a single, fixed ratio of 78% to 80% suggested by researchers for anterior teeth, the clinician should adopt different crown width-height ratios to restore teeth with the optimum esthetic outcome.
Topics: Adult; Body Height; Cuspid; Esthetics; Esthetics, Dental; Face; Female; Humans; Incisor; Male; Odontometry; Photography, Dental; Sex Factors; Tooth Crown
PubMed: 35229002
DOI: 10.1155/2022/4695193 -
BMC Oral Health Dec 2023To evaluate the effects of root canal treatment (RCT) and post-crown restoration on stress distribution in teeth with periapical bone defects using finite element...
AIM
To evaluate the effects of root canal treatment (RCT) and post-crown restoration on stress distribution in teeth with periapical bone defects using finite element analysis.
METHODOLOGY
Finite element models of mandibular second premolars and those with periapical bone defects (spherical defects with diameters of 5, 10, 15, and 20 mm) were created using digital model design software. The corresponding RCT and post-crown restoration models were constructed based on the different sizes of periapical bone defect models. The von Mises stress and tooth displacement distributions were comprehensively analyzed in each model.
RESULTS
Overall analysis of the models: RCT significantly increased the maximum von Mises stresses in teeth with periapical bone defects, while post-crown restoration greatly reduced the maximum von Mises stresses. RCT and post-crown restoration slightly reduced tooth displacement in the affected tooth. Internal analysis of tooth: RCT dramatically increased the maximum von Mises stress in all regions of the tooth, with the most pronounced increase in the coronal surface region. The post-crown restoration balances the internal stresses of the tooth and is most effective in periapical bone defect - 20-mm model. RCT and post-crown restoration slightly reduced the tooth displacement in all regions of the affected tooth.
CONCLUSIONS
Root canal treatment seemed not to improve the biomechanical state of teeth with periapical bone defects. In contrast, post-crown restoration might effectively balance the stress concentrations caused by periapical bone defects, particularly extensive ones.
Topics: Humans; Finite Element Analysis; Tooth Crown; Dental Pulp Cavity; Crowns; Periapical Periodontitis
PubMed: 38057755
DOI: 10.1186/s12903-023-03612-9 -
Scientific Reports Oct 2017Mammalian teeth have diverse pattern of the crown and root. The patterning mechanism of the root position and number is relatively unknown compared to that of the crown....
Mammalian teeth have diverse pattern of the crown and root. The patterning mechanism of the root position and number is relatively unknown compared to that of the crown. The root number does not always match to the cusp number, which has prevented the complete understanding of root patterning. In the present study, to elucidate the mechanism of root pattern formation, we examined (1) the pattern of cervical tongues, which are tongue-like epithelial processes extending from cervical loops, (2) factors influencing the cervical tongue pattern and (3) the relationship among patterns of cusp, cervical tongue and root in multi-rooted teeth. We found a simple mechanism of cervical tongue formation in which the lateral growth of dental mesenchyme in the cuspal region pushes the cervical loop outward, and the cervical tongue appears in the intercuspal region subsequently. In contrast, when lateral growth was physically inhibited, cervical tongue formation was suppressed. Furthermore, by building simple formulas to predict the maximum number of cervical tongues and roots based on the cusp pattern, we demonstrated a positive relationship among cusp, cervical tongue and root numbers. These results suggest that the cusp pattern and the lateral growth of cusps are important in the regulation of the root pattern.
Topics: Animals; Mice; Mice, Inbred ICR; Rats; Rats, Sprague-Dawley; Tooth Cervix; Tooth Crown; Tooth Root
PubMed: 28983077
DOI: 10.1038/s41598-017-12745-1 -
BMC Evolutionary Biology Dec 2018Several lineages of herbivorous mammals have evolved hypsodont cheek teeth to increase the functional lifespan of their dentition. While the selective drivers of this...
BACKGROUND
Several lineages of herbivorous mammals have evolved hypsodont cheek teeth to increase the functional lifespan of their dentition. While the selective drivers of this trend and the developmental processes involved have been studied in greater detail, thus far no quantitative information is available on the relationship between additional investment into tooth growth and the resulting extension of the functional period of these teeth. To achieve this, we performed a detailed analysis of molar crown growth in known-age Soay sheep repeatedly injected with different fluorochromes.
RESULTS
Our study revealed that in sheep molars especially the formation of the crown base portion is prolonged in comparison with other herbivorous artiodactyl species. Our results demonstrate that growth of the crown base accounted for more than half of the total crown formation time (CFT) of the anterior lobes of the first (approx. 220 days of total CFT of 300 days), second (approx. 260 of 460 days) and third (approx. 300 of at least 520 days) molars, and that the formation of this crown portion occurred largely after the teeth had already reached functional occlusion. By combining data on wear-related changes in crown morphology from the literature with the reconstructed additional investment into the crown base portion, it was possible to relate this additional investment to a prolongation of the functional periods of the molars ranging from 4 years in the M to 6 years in the M.
CONCLUSIONS
Our results allow to establish a quantitative link between an additional investment into molar crown growth of sheep and the extension of the functional period of these teeth. The reported findings enable an assessment of the adaptive value, in terms of increased longevity, of an additional investment into crown elongation in a mammalian herbivore.
Topics: Animals; Dental Enamel; Female; Herbivory; Male; Molar; Sheep, Domestic; Tooth; Tooth Crown
PubMed: 30594146
DOI: 10.1186/s12862-018-1332-9 -
Journal of Dental Research Oct 2010Epithelial-mesenchymal interactions guide tooth development through its early stages and establish the morphology of the dentin surface upon which enamel will be... (Review)
Review
Epithelial-mesenchymal interactions guide tooth development through its early stages and establish the morphology of the dentin surface upon which enamel will be deposited. Starting with the onset of amelogenesis beneath the future cusp tips, the shape of the enamel layer covering the crown is determined by five growth parameters: the (1) appositional growth rate, (2) duration of appositional growth (at the cusp tip), (3) ameloblast extension rate, (4) duration of ameloblast extension, and (5) spreading rate of appositional termination. Appositional growth occurs at a mineralization front along the ameloblast distal membrane in which amorphous calcium phosphate (ACP) ribbons form and lengthen. The ACP ribbons convert into hydroxyapatite crystallites as the ribbons elongate. Appositional growth involves a secretory cycle that is reflected in a series of incremental lines. A potentially important function of enamel proteins is to ensure alignment of successive mineral increments on the tips of enamel ribbons deposited in the previous cycle, causing the crystallites to lengthen with each cycle. Enamel hardens in a maturation process that involves mineral deposition onto the sides of existing crystallites until they interlock with adjacent crystallites. Neutralization of acidity generated by hydroxyapatite formation is a key part of the mechanism. Here we review the growth parameters that determine the shape of the enamel crown as well as the mechanisms of enamel appositional growth and maturation.
Topics: Ameloblasts; Amelogenesis; Animals; Calcium Phosphates; Dental Enamel; Dental Enamel Proteins; Durapatite; Enamel Organ; Humans; Tooth Calcification; Tooth Crown
PubMed: 20675598
DOI: 10.1177/0022034510375829 -
Medical Science Monitor : International... Mar 2022BACKGROUND The ratio between a tooth root and its crown is an essential diagnostic parameter that determines treatment options. This radiographic study used panoramic...
BACKGROUND The ratio between a tooth root and its crown is an essential diagnostic parameter that determines treatment options. This radiographic study used panoramic dental radiographs or orthopantograms to measure the mean root (R)-to-crown (C) ratios (R/C) of the permanent teeth in 81 Saudi adults. MATERIAL AND METHODS A total of 81 panoramic radiographs of Saudi adult patients (40 males and 41 females) previously treated in the College of Dentistry, Saudi Arabia, aged 16-35 years, were selected. The crown height and root length for each tooth were measured on the digital panoramic radiographs. The correlation coefficient (intra-class) was calculated to assess the intra-examiner reproducibility and a good agreement was achieved (ICC=0.79-0.89). RESULTS For both males and females, the highest mean R/C ratio was for maxillary canine (1.91) and for mandibular second premolar (2.0) while the lowest R/C ratio was for maxillary first molar (1.64) and for mandibular central incisor (1.59). Except for the maxillary second premolar, no significant differences in R/C ratios were observed for maxillary arch. In the mandibular arch, the R/C ratio for lateral incisor, both premolars, and molars differed significantly (P<0.05). Among males, statistically significant differences between teeth existed in R/C ratios for central and lateral incisors, second premolar, and both molars (P>0.05). For females, significant differences between teeth in R/C ratios were observed for both premolars and both molars (P>0.05). CONCLUSIONS This study supports the findings from previous studies that orthopantograms can be used to calculate root/crown ratios, which varies between males and females and the dental arch among Saudi adults.
Topics: Adolescent; Adult; Dentition, Permanent; Female; Follow-Up Studies; Humans; Male; Radiography, Panoramic; Reproducibility of Results; Retrospective Studies; Saudi Arabia; Tooth Crown; Young Adult
PubMed: 35235552
DOI: 10.12659/MSM.936085 -
The Journal of Forensic... May 2019The aim of this study was to determine whether the tooth crown sexual dimorphism pattern reported in previous small studies can be generalized for a broader range of... (Meta-Analysis)
Meta-Analysis
OBJECTIVE
The aim of this study was to determine whether the tooth crown sexual dimorphism pattern reported in previous small studies can be generalized for a broader range of populations.
LITERATURE REVIEW
A systematic literature review was performed by two independent examiners. The following databases were searched from October 2015 to July 2016: PubMed, Scopus, Lilacs, ScienceDirect, Medline, and Cochrane Reviews. No language restrictions were applied to the search.
SELECTION CRITERIA
The inclusion criteria comprised original studies investigating mesiodistal permanent teeth that reported the sample population and standard deviation. All right-sided teeth, except the third molars, were measured and separated by sex in the included studies. Thirty-one studies were included in the quantitative data synthesis and meta-analysis. Studies of non-human teeth, skeletal remains, or an overly specific study population were excluded.
MAIN RESULTS
Thirty-one trials, involving 6481 participants, provided data for the meta-analysis of teeth. Sexual dimorphism in mesiodistal crowns was found in all teeth across a range of populations, principally in lower canines (5.73%) and maxillary canines (4.72%), followed by the lower second molars (3.54%) and upper second molars(3.20%), and finally in the lower first molars(3.14%) and upper first molars(2.64%).
CONCLUSIONS
A small degree of sexual dimorphism exists in all human teeth. Second molars and canines show the greatest sexual dimorphism. Additionally, smaller racial differences are present in mesiodistal crowns among groups living in different geographic areas; however, it is not possible to establish a single value applicable for all populations.
Topics: Humans; Odontometry; Sex Characteristics; Tooth Crown
PubMed: 31187738
DOI: No ID Found -
The Angle Orthodontist Jul 2014To evaluate and compare three-dimensional tooth size symmetry in the right and left sides of upper and lower dental arches in cleft lip and palate (CLP) patients and to... (Comparative Study)
Comparative Study
OBJECTIVE
To evaluate and compare three-dimensional tooth size symmetry in the right and left sides of upper and lower dental arches in cleft lip and palate (CLP) patients and to compare it with an Angle Class I normal occlusion control group.
MATERIALS AND METHODS
Dental casts of 72 individuals with CLP (20 bilateral [BCLP], 34 unilateral left [ULCLP], and 18 unilateral right [URCLP]) and 53 individuals with Class I occlusion, all with permanent dentition, were randomly selected. Mesiodistal (MD), labiolingual (LL), and occlusogingival (OG) measurements of upper and lower teeth were recorded with a digital caliper. Descriptive statistics and paired t-test were used for statistical analysis.
RESULTS
Significant asymmetries were found between the right and left sides of the dental arches in CLP as follows: MD dimension: mandibular first premolar (ULCLP, P < .01); LL dimension: mandibular first premolar (URCLP, P < .05); OG dimension: maxillary central incisor and first premolar (ULCLP, P < .05 and P < .01, respectively), central incisor (BLCLP, P < .01), mandibular canine and first premolar (ULCLP, P < .01), and first molar (ULCLP, P < .05). Tooth crown size asymmetries were also recorded in the Class I group.
CONCLUSIONS
Significant three-dimensional tooth size asymmetries were found in CLP subjects; however, such asymmetries were also present on the Class I control group.
Topics: Adolescent; Bicuspid; Cleft Lip; Cleft Palate; Cuspid; Dental Arch; Female; Humans; Imaging, Three-Dimensional; Incisor; Male; Mandible; Maxilla; Molar; Odontometry; Retrospective Studies; Tooth Crown
PubMed: 24423204
DOI: 10.2319/072013-526.1