Crown Index Research Articles

Morphology of Deciduous Canines in African Apes

The aim of this study was to determine the morphology and sexual dimorphism of deciduous canines in African great apes. The morphology of the deciduous canines of the chimpanzee and the gorilla was similar in both the male and the female. The occlusal view of the chimpanzee showed an ellipsoid shape in the maxilla and a more distorted quadrilateral shape in the mandible. The lingual view showed a pyramidal triangle in the maxilla and a distorted square in the mandible. Compared to chimpanzees, gorillas had a larger maxillary labiolingual diameter, a more elliptical shape, a higher crown height and more mesial grooves. The basal tubercles, spinous processes and distal accessory ridges observed in human primary canines were not observed in chimpanzees and gorillas. No significant sex differences were found for maxillary and mandibular primary canines in chimpanzees. However, in the maxilla, there were significant sex differences in gorillas for all variables except mesiodistal diameter. Compared to humans, chimpanzees were significantly larger for all variables except maxillary labiolingual diameter. On the other hand, the crown index was significantly larger in humans and the occlusal view was more rounded. The deciduous canines of chimpanzees and gorillas were similar in morphology to the permanent canines of females of both species. However, they differed significantly from the permanent canines of males.

Stand density and crown growth assessment of Anogeissus pendula Edgew in Tropical dry deciduous forests of Rajasthan (India)

The present studies were carried out to assess the stand and crown growth of Anogeissus pendula (Dhav) in tropical dry deciduous forest at Jhalawar Forest Division, Rajasthan, India. Density of each site was determined by calculating the number of trees and basal area per hectare of the site . The results revealed that the Mishroli (S 3 ) performed highest for growth parameters viz., dbh (26.20 cm), height (11.65 m), basal area (17.2 m 2 /ha), volume (37.73 m 3 /ha) and crown height (2.48 m) with lowest density (362.50 tree/ha), whereas, minimum has been observed for the same parameters at Bagher (S 1 )with highest density (535 trees/ha) and reverse is true for form factor (0.18) at above sites. Performance at Mishroli (S 3 ) has been attributed to lower density, trees of higher diameter class indicates its site as good site quality compared to others. The poor performance at S 1 was attributed to high level of disturbance as observed in field. The crown level stand structure at S 3 reported good performance for the parameters viz., crown width (8.89 m), crown length (9.46 m), crown basal area (63.62 m 2 /tree), crown index (1.07), crown percent (80.79 %), crown surface area (149.18 m 2 /tree). Crown projection ratio (44.99) and crown quotient to ground cover (3782.78) reported highest at Ghatoli (S 4 ) and minimum (34.53) and (1213.02) at Mishroli (S 3 ), due to high density level causing low mean dbh at S 4 relatively to Mishroli (S 3 ).

Measurement of the morphological data of primary teeth in northwest China.

This study aims to digitally obtain the morphological data of children's primary teeth in northwest China and evaluate the reliability of digitally obtaining the anatomical morphological data of primary teeth. A total of 308 extracted primary teeth and cone-beam computed tomography (CBCT) images of 407 primary teeth were collected in northwest China. Electronic digital Vernier callipers (accuracy: 0.01 mm) were used to measure the mesiodistal and buccolingual diameters and crown length of the extracted primary teeth and calculate the crown area and crown index. Each sample was scanned with an intraoral scanner (Trios2 3shape, Denmark), and the resulting stl format files were imported into Geomagic Wrap 2015 to measure the axial and buccolingual diameters and crown length. The crown area and crown index were then calculated. After verifying the accuracy of the CBCT image measurement, the CBCT image data of 407 samples were measured in SmartV software using the "measure length" function by referring to the coronal, sagittal, and horizontal planes to adjust the position of the reference line. Northern Chinese have larger primary teeth than other populations (Japanese, white American, African, Icelander, Spanish, and Dominican Mestizo) but smaller primary teeth than native Australians. Compared to Indian primary teeth, northwest Chinese's primary teeth have larger diameters on the central axis and smaller diameters on the buccolingual surface. Male teeth are usually larger than female teeth. Compared with the results of Wang Huiyun's study, the axial and buccolingual diameters and crown length of all native tooth types in this total sample were significantly smaller at the 0.1% level, and only the axial diameters of the upper first molar and lower second molar and the crown length of the lower lateral incisor were significantly smaller at the 1% level. The results of the intraclass correlation coefficient of 308 extracted primary teeth expressed an excellent degree of agreement between the callipers and intraoral scanner for the following: mesiodistal diameter (0.956-0.991), buccolingual diameter (0.963-0.989), crown length [0.864-0.992, except for the upper canine (0.690)], crown index (0.850-0.975), and crown area (0.946-0.993). The digital measurements of the intraoral scanner and CBCT image are in good agreement with the manual measurement of the Vernier calliper. The difference between the anatomical morphology size of the primary teeth measured in this study and the results of different populations could be due to different genetic backgrounds and environmental factors.

Dimension variability of the M2 human molar teeth: comparisons between prehistoric and medieval samples

Teeth are a valuable source of information for studies regarding past human populations in archaeological and forensic contexts. In dental anthropology, the linear measurements of tooth crowns are used for assessing morphological variability and sexual dimorphism in both modern and past human populations. The aim of this research is to evaluate the M2 molar crown variability in archaeological human populations from Prehistory (Chalcolithic and Bronze Age, ~ 5000-1150 BCE) and Middle Ages (13th-17th centuries) discovered in sites from North-Eastern Romania. The objectives of this study emphasize on the diachronic comparison of the M2 molar crown variables between prehistoric and medieval samples (1), and the assessment of sexual dimorphism expression (2). The two crown measurements, mesio-distal (MD) and bucco-lingual (BL) diameters, were performed using ImageJ software on occlusal digital images acquired stereo-microscopically. The crown index (CI), crown area (CA) and the sexual dimorphism index (SDI), along with the two linear measurements, were subjected to univariate and multivariate statistical analysis. Our results show that the variation coefficient (CV) differs for the MD variable in the female upper M2 molars, being higher in the medieval sample than the prehistoric one; also, a higher variability is remarked for the mandibular molar in the medieval sample than in prehistoric one. In females, the MD and CA variables for mandibular M2 molars and the BL and CA for maxillary molars showed significant statistical differences between the medieval and prehistoric mandibular teeth, with higher values for the exemplar from Middle Ages. Similar result was obtained in males, for the CA variable in the upper M2 molars. In our study, the sexual dimorphism manifested at the M2 crown molar was highlighted in the prehistoric sample, though less in the medieval one.

Esthetic evaluation of single implant-supported prostheses: Comparative analysis of the reliability of the esthetic indices.

To carry out a detailed analysis of four indices proposed for the esthetic evaluation of implant-supported single crowns in the anterior maxillary sector. Four esthetic indices were selected: the Pink and white esthetic score, the Copenhagen Index Score, the peri-implant and crown index (PICI), and the implant restoration esthetic index (IREI). The examiners were 15 expert subjects and 30 nonexpert ones. The intraclass correlation coefficient was used to assess reproducibility. The validity and the correlation of the esthetic indices results with the perception of nonexpert subjects were evaluated using the Pearson's correlation. For inter- and intra-observer reproducibility, all the esthetic indices had an intraclass correlation coefficient value>0.8. As for validity, the highest correlation values were found for the PICI and for the IREI. The values of correlation with the perception of nonexpert subjects did not exceed 0.3 for all esthetic indices. All esthetic indices evaluated presented good intra- and inter-rater reproducibility. Validity was considered satisfactory only for the PICI and the IREI. The correlation with the perception of nonexpert subjects showed a weak correlation with all the indices considered. An approved esthetic indice with proven reproducibility and validity could provide a better objective overview of one's own esthetic results in the daily practice. It could also help to record the results over time to analyze the stability of the treatment procedure. The esthetic results of the different surgical and prosthetic protocols can also be compared, which facilitates the analysis of the indications relevance and clinical effects. However, low reproducibility according to the specialty and the practitioner's level of expertise was observed. A heterogeneity of results was also noted when compared with those of nonexpert subjects.

Yield and crown structure characteristics in a red oak (Quercus rubra L.) stand: Case study

The paper provides the results of a detailed analysis of timber volume and several important crown variables of red oak (Quercus rubra L.) based on an experimental plot in eastern Hungary. At the age 32 years the crop trees belonged to different height classes. If the volume of the mean tree from height class I was considered as 100%, the volume of the mean tree of class II was 59%, and the mean tree of class III was only 36%. It appeared that there was a significant correlation between crown indices and yield. For this reason, diameter at breast height showed a positive linear correlation with crown diameter (R2= 0.6211). Additionally, there was also positive linear relationship between crown diameter and volume (R2= 0.6908). The variation of crown indices is height even within the same stand and indicates the importance of following a selective thinning operation method.

Tree form morphometrics of Agathis dammara and Acacia mangium in the IPB’s Dramaga Landscape Campus, Bogor

Tree growth comprises diverse tree forms and crown shapes that are influenced by the growing space and are related to biomechanical responses. Due to the complex structures of tree forms and crown architecture, more understanding of their functions is necessary. The study aimed to evaluate the morphometrics of two tree species of contrasting tree forms. Each represents excurrent and decurrent crown architectures located in the Dramaga Campus Landscape, Bogor. Morphometric analysis was conducted on those two species, namely excurrent agathis (n=23 trees) and decurrent mangium (n= 15 trees). The morphometric analysis was carried out for several basic growth variables such as diameter at breast height, total height, and crown height. In addition, other variables and parameters were also assessed, namely live crown ratio, slenderness ratio, crown diameter, crown projection area, crown index, and coefficient of space for growth. The results showed that the average diameters of agathis and mangium trees in this study were 0.49 and 0.48 m, respectively, while the average heights were 24.63 m and 18.23 m, respectively. The live crown ratio of both trees was more than 80%. The average slenderness ratio for agathis trees was 50.66 higher than that of mangium trees (40.64). The crown projection areas for agathis and mangium were 37.60 m2 and 69.69 m2, respectively. On the other hand, the crown index of agathis was 3.20, and mangium was 1.84. The coefficient of space for the growth of agathis and mangium was 0.14. and 0.19. The information related to tree morphometry is important for tree management, especially in evaluating healthy and steady tree stands.

Permanent Maxillary Odontometrics for Sex Estimation Based on a 3-Dimensional Digital Method.

BackgroundIn the field of forensic medicine, sex estimation is a critical step in personal identification. Teeth are the hardest tissue and have high temperature resistance and corrosion resistance. In cases such as an airplane crash or the corpse of an unknown person, teeth often play a crucial role in identification. This study applied 3-dimensional technology to obtain odontometrics of permanent maxillary teeth and to examine the sexual dimorphism, finding suitable discriminant indicators to construct appropriate equations for sex estimation.Material/MethodsA total of 204 participants (104 men and 100 women) from the Han population in Kashgar were included. Plaster models of their maxillary dentition were obtained to scan and measure through an accepted and commonly used 3-dimensional digital method. Descriptive statistics, t tests, and discriminant analyses were statistically analyzed using IBM SPSS 23.0 software.ResultsThis study showed high intra- and interexaminer reliability (intraclass correlation coefficient >0.950). There were statistically significant sex-related differences (P<0.05), with male values generally being higher for buccolingual distance, mesiodistal distance, intercanine distance, crown area, crown module, crown index, and maxillary canine index. Compared with other measurements, mesiodistal distance and crown area indicator exhibited distinct sexual dimorphism. In addition, several appropriate equations were constructed through different discriminant analyses that could be used to estimate sex in our specific population.ConclusionsThree-dimensional digital technology offers a promising method for odontometry. Combining mesiodistal distance and buccolingual distance of particular teeth or using maxillary canine index in discriminant functions are acceptable auxiliary tools for sex estimation in the forensic field.

Assessment of the effects of thinnings in scots pine plantations in Mongolia: a comparative analysis of tree growth and crown development based on dominant trees

The post-thinning stand density and spacing in forest plantations influence individual tree growth and crown development, and the changes detected in dominant tree growth are a good indication of the thinning effect. The objective of this study was to determine the effects of different thinning intensities on diameter and height growth in a Scots pine (Pinus sylvestris L.) plantation. The field measurements were carried out between 2016 and 2020 on a Scots pine plantation, growing in Selenge province of northern Mongolia. Following this, experimental thinnings were carried out with different intensities. Thinning treatments comprised thinning with very low, low, medium, and high intensities, as well as an unthinned control stand. Stem analyses were performed to calculate the annual and cumulative diameter, height, and volume growth. For tree crown measurements several parameters were analyzed: crown diameter, crown projection area, and crown index. A total of 300 trees (5 treatments*3 replications*20 dominant trees from each plot) were subjected to the comparative analyses. This study revealed that thinning showed a stronger positive effect on diameter and volume growth of dominant trees in the plantation. Our results showed a gradual increase in diameter, basal area, and volume growth depending on the thinning intensity. An ANOVA test for growth analyses of dominant trees showed a significant difference in diameter (p < 0.0001) and height (p < 0.0001) growth performance following experimental felling with different thinning intensities. Finally we elaborated linear mixed effect models (LMM) for tree growth between 2016 and 2020 of selected dominant trees. With the help of the LMM we analyzed and described the thinning impact on DBH, BA, height, volume and crown diameter. The models confirmed that higher thinning intensity triggered growth of the response variables except for height. A greater height growth was found in very low (10%) and low (15%) intensity treatments. Due to reduction of competition and optimization of the distance between individuals, thinnings contributed to a relatively faster development of the tree crown in radial directions. Based on our analysis results and comparative graphs representing post-thinning dominant tree growth in diameter, height, basal area, and volume, we recommend medium- (30%) and high-intensity (45%) thinnings as at the beginning stage of plantation establishment.

Bibliometric indicators to evaluate scientific activity

Bibliometric indicators have been devised to quantify scientific production and to try to evaluate its impact in the community. In general, bibliometric indicators can be classified according to whether the unit of analysis is the author (individual or group) or journal. The most widely used indicators for authors are those that measure an individual author’s production, such as the Crown index or the h-index and its derivatives (e-index, h5-index, and the absolute or Ab-index, among others). The bibliometric indicators devised to try to evaluate journal quality are associated with Journal Citation Reports (e.g., impact factor, field-weighted citation impact, Eigenfactor, and article influence) or with Scopus (Scimago Journal Rank (SJR), source normalized impact per paper (SNIP), and CiteScore). This article describes the main bibliometric indicators, explains how they are calculated, and discusses their advantages and limitations.

Aesthetic Parameters and Patient-Perspective Assessment Tools for Maxillary Anterior Single Implants.

Background This review aimed to concisely describe the current aesthetic objective indices for a single-implant maxillary anterior crown. The secondary aim was to propose introducing a unified, standardized questionnaire for adequately collecting patient-reported outcome measures (PROMs) in implant dentistry. Materials and Methods A literature review was conducted using both EMBASE/Ovid and MEDLINE/PubMed databases by combining keywords and Emtree/Mesh terms related to “Esthetics,” “Self-Assessment or Surveys and Questionnaires,” and “Single-Tooth Dental Implants.” Results The most meaningful aesthetic objective indices for single implants in the literature are the Pink Esthetic Score (PES), the Papilla Presence Index (PPI), Peri‐Implant and Crown Index (PICI), PES/White Esthetic Score (PES/WES), the Implant Crown Aesthetic Index (ICAI), and a modified version of the ICAI (mod-ICAI) index. Clearly, PES/WES is still the most widely accepted tool. It is encouraging to observe that there is an increasing tendency in recent years to report PROMs more frequently in the implant dentistry literature. We proposed the implementation of a unified, standardized questionnaire using a self-administered visual analogue scale (VAS) scoring system, which evaluates overall satisfaction, comfort, tooth appearance, gingival appearance, function, and hygiene complexity. This tool should be validated in the oral implantology research context for its regular implementation or further development. Conclusions Conducting qualitative studies among dental implant patients who received few implants or single-tooth implant reconstructions in the aesthetic zone may help dental researchers understand better how to efficiently develop and validate a quantitative instrument. This standard tool would reduce heterogeneity bias by providing comparable data between studies.

Indicadores bibliométricos para evaluar la actividad científica

Bibliometric indicators have been devised to quantify scientific production and to try to evaluate its impact in the community. In general, bibliometric indicators can be classified according to whether the unit of analysis is the author (individual or group) or journal. The most widely used indicators for authors are those that measure an individual author's production, such as the Crown index or the h-index and its derivatives (e-index, h5-index, and the absolute or Ab-index, among others). The bibliometric indicators devised to try to evaluate journal quality are associated with Journal Citation Reports (e.g., impact factor, field-weighted citation impact, Eigenfactor, and article influence) or with Scopus (Scimago Journal Rank (SJR), source normalized impact per paper (SNIP), and CiteScore). This article describes the main bibliometric indicators, explains how they are calculated, and discusses their advantages and limitations.

Zirconium dioxide implants as an alternative to titanium: A systematic review.

BackgroundThis systematic review evaluates the available scientific literature to demonstrate the aesthetic and clinical benefits and to determine the survival and the success of zirconium dioxide implants concerning titanium implants. Material and MethodsThe electronic databases were searched until January 2020. Outcome measures were pink aesthetic score (PAS), white aesthetic score (WAS), bleeding on probing (BOP) and probing depth (PD). The addressed PICO question was: In partially edentulous patients in the upper-anterior sector, do zirconium dioxide implants provide aesthetic benefits over conventional titanium implants? ResultsIn the 15 articles included after the screening were evaluated respectively, the pink aesthetic score, white aesthetics score, the peri-implant, and crown index, bleeding on probing, plaque index, probing pocket depth, radiographic bone loss, papilla height, and survival and success rate. The results show how the aesthetic and clinical benefits and the survival and success rate of zirconium dioxide implants are, in general, better than titanium implants. ConclusionsDespite the optimal aesthetics, clinical and survival results obtained in the review, more studies are needed to confirm these data. Key words:Ceramic dental implants, zirconia implants, esthetics, zirconium dioxide and zirconia.

Modeling form factors for sal (Shorea robusta Gaertn.) using tree and stand measures, and random effects

Form factor (FF) is widely used for the correct estimation of tree volume. Few FF models have been developed and applied to the volume estimation, however, they have failed to account for the influence of important tree and stand characteristics on the FF variations. We aimed to incorporate the effects of these characteristics into the FF models for sal (Shorea robusta Gaertn.) trees in Nepal. A comprehensive data set representative to wide variations of tree size, crown architecture, stem form, stand density, site productivity, and environmental condition was used for the purpose. We evaluated various tree and stand measures characterized by the meaningful biological explanation as predictors in the FF models. The unstructured random component accounting for the subject-specific (diameter class-specific) random effects was included into the FF model through the application of the mixed-effects modeling. Among several predictor variables evaluated, tree height (HEIGHT), crown index (ratio of crown depth to crown diameter, CI), relative diameter (ratio of the subject tree DBH to quadratic mean DBH, Dq), and basal area proportion of the species of interest (BAPRO) significantly contributed to the FF variations. The FF models described the substantial proportion of the FF variations. There was an increased FF with increasing HEIGHT and BAPRO, but decreased FF with increasing Dq and CI. The FF was influenced significantly differently by different covariate predictors with the biggest influence of Dq followed by CI, HEIGHT, and BAPRO. Calibration of the mixed-effects FF models with the random effects estimated from the complimentary FF of four sample trees per DBH class could provide the highest prediction accuracy. Inclusion of tree- and stand-level measures, and subject-specific random effects into the FF models could significantly increase the FF prediction accuracy and increase the biological robustness of the models.

Tree height inversion combining light detection and ranging and optical remote sensing data

Tree barriers in transmission line corridors are an important safety hazard.Scientific prediction of tree height and monitoring tree height changes are essential to solve this hidden danger. In this paper, the advantages of airborne lidar and optical remote sensing data are combined to research the method of tree height inversion. Based on glas data of lidar,waveform parameters such as waveform length, waveform leading edge length and waveform trailing edge length were extracted from waveform data by gaussian decomposition method.Terrain feature parameters were extracted from aster gdem data.The tree crown information was extracted from the optical remote sensing image by means of the mean shift algorithm. Then extract the vegetation index with high correlation with tree height.Finally, the extracted waveform feature parameters, topographic feature parameters, and crown index and vegetation index with high correlation are used as model input variables. The tree height inversion model was established using four regression methods, including multiple linear regression (mlr), support vector machine (svm), random forest (rf), and bp neural network (bpnn). The accuracy evaluation was conducted, and it was concluded that the tree height inversion model based on random forest obtained the best accuracy effect.

Prediction of Sex from Teeth Linear Dimensions and Indices

Determination of sex is one of the most important and vital steps in forensic medicine. Sexual dimorphism using odontometric analysis is found to vary in different populations making it necessary to attain values of a specific population which makes identification of person as easy as possible. The present study aims to establish sexual differentiation using dental parameters including dental linear dimensions and indices. Maxillary jaw casts from total of 100 subjects (50 males and 50 females) between ages 17 and 24 years were taken. Mesiodistal (MD) and Buccolingual (BL) dimensions of each tooth of from maxillary jaw cast excluding third molar were measured using precision calipers, dental indices were calculated. Data was collected and statistical analysis was done using SPSS software version 20. Bucccolingual dimension was proved to be a better parameter than MD for assessment of gender in case of left central incisor, canines and left first molar. Crown index of right central incisor, second premolars, and left first molars was the best index for sex prediction of most of the teeth.

A GENERALIZED ABOVEGROUND BIOMASS MODEL FOR JUVENILE INDIVIDUALS OF Rhododendron arboreum (SM.) IN NEPAL

ABSTRACT Carbon in the juvenile plants contribute significant share to the total carbon stock in forests. A precise estimate of aboveground biomass of the juvenile stages of trees is therefore very important. We developed a generalized allometric biomass model for the prediction of aboveground biomass of the juvenile individuals of Rhododendron arboreum (Sm.). We used data from 66 destructively sampled juveniles of R. arboreum in Gorkha district- one of the mountainous districts in Nepal, for the purpose. Using eight nonlinear functions of various forms (power, exponential, fractional forms), we evaluated several individual-level characteristics, such as size (diameter, height), crown measures (crown ratio, crown width, crown spread ratio, crown index, crown fullness ratio), height-to-diameter ratio (plant bole slenderness), number of branches, wood density, and stand-level characteristics, such as altitude and slope of sites for their potential contributions to the biomass variations of the juvenile individuals. A simple power function with cross-product of the squared-diameter and height as a main predictor and crown spread ratio as a covariate predictor showed the best fit to data (R2 adj=0. 90); RMSE=59.35 g) without substantial trends in the residuals. Our model is site-specific and its application should therefore be limited to those stands which were the basis of this study. Further works on recalibration, validation, and verification of our model using a larger dataset collected from a wider range of species distribution will be more interesting.

Características estructurales de un bosque de pino en Tlalnepantla, Morelos

El principal tipo de vegetación del municipio Tlalnepantla, localizado al noreste del estado de Morelos, corresponde al de bosques templados de pino y de pino-encino. Forma parte de la zona de amortiguamiento y de recarga de mantos del centro de la entidad. En la localidad La Correa se hizo una descripción dasonómica de la población forestal y un diagnóstico de la situación sanitaria del arbolado, como antecedente para diseñar un proyecto ecoturístico local. Se aplicó un muestreo sistemático mediante el establecimiento de 20 parcelas de 1/10 ha. Las condiciones sanitarias de la copa, el tronco y el vigor, se analizaron con una prueba de X2. El análisis demográfico se hizo mediante tablas de vida estática y se diseñaron curvas de supervivencia para cada especie. Se realizó un análisis morfométrico a partir del porcentaje de copa, el índice de copa, la dimensión de la copa, el índice de espacio vital y el grado de esbeltez por clase natural de edad por taxón, como indicadores de competencia y calidad de sitio del arbolado. Se identificaron cuatro especies: Pinus patula, P. ayacahuite, P. leiophylla y P. montezumae. Los resultados indican que el bosque de pino estudiado es una masa mixta regular, con una densidad promedio de 437 ejemplares ha-1, conformada, principalmente, por individuos jóvenes que se desarrollan en lugares propios de baja competencia, con buenos porcentajes sanitarios y vigorosos.

Assessment of Sexual Dimorphism of Teeth by Dental Indices

Background : Odontometry is an important parameter to demonstrate sexual dimorphism. Aim and Objective : The study aimed to assess the efficiency of dental indices in identifying sexual dimorphism in permanent human dentition. Material and Methods : Dental casts (n=101; 49 male and 52 female) were retrieved from the archives. The mesio-distal (MD) and bucco-lingual (BL) dimensions of the permanent teeth (from central incisor to second molar) were measured using digital Vernier Caliper. Crown area, crown module, crown index, incisor and canine index were calculated for each individual. Results and Conclusions :Sexual dimorphism in teeth are attributed to hormonal influence and Ychromosome. The BLdimension is less influenced by attrition compared to the MD dimension making it a better identifier. Discriminant function analysis showed MD dimension of mandibular left canine and crown index of right maxillary premolar as the most reliable predictors. Binary logistic regression analysis showed, the MD dimension of the lower left canine was the single best predictor of gender.

American Black-White Differences in Primary Tooth Crown Shape: The Crown Index

The purpose of this tooth-size study was to compare the crown index—the ratio of buccolingal to mesiodistal crown size—in the primary teeth of contemporary American blacks and whites. Maximum MD and BL drown dimensions were obtained with sliding calipers from dental casts of children attending the graduate pedodontic and orthodontic clinics at the University of Tennessee, Memphis (n = 226). The crown index (BL/MD times 100) was calculated for all 10 tooth types (left and right sides were averaged prior to calculation). Only the maxillary first molar exhibited a significant sex difference (girls have a higher crown index). In contrast, 9 of the 10 tooth types have signficantly higher crown indices in blacks than whites. Analysis of the MD and BL crown diameters reveals that the race differencs are due exclusively to differences in mesiodistal crown lengths; the buccolingual crown breadths do not differ between these two races. Consequently, the crown indices are higher in blacks because of their larger MD dimensions. Differences in the indices conform to prior findings that American blacks have larger tooth crowns than whites in both the primary and permanent dentitions, and this study shows that the differences are due to the MD not the BL crown axis. Study of the crown components will shed light on how the crown shapes differ between these two races.