Dental non-metric traits of Han and Zhuang people / 解剖学报

[Abstract] Objective To investigate the relationship between the Han, Zhuang and the World populations by comparing the frequency of dental non-metric traits. Methods From 2015 to 2019, ten dental non-metric traits were sampled from He’nan, Jiangsu and Guangxi Zhuang Autonmous Region, with sample size of 1785(674 He’ nan, 547 Jiangsu, 388 Guangxi Han, 176 Guangxi Zhuang). Principal component analysis, multidimensional scaling and neighbor network were carried out. Results East Asian populations could be clearly divided into two major groups, Northeast Asian and Southeast Asian. Han and Zhuang populations were close to the Northeast Asian populations, but were far from the Southeast Asian populations. There were also some north-south differences within Han populations. Conclusion Both Sundadonty and Sinodonty are existed in East Asian populations. Han and Zhuang populations dental non-metric traits are closer to the Sinodonty.

Investigación de rasgos dentales no métricos en poblaciones sudamericanas actuales: estado de situación y contextualización forense / Research on non-metric dental traits in present South-American populations: state of art and forensic contextualization

En las poblaciones humanas recientes existe una patrón de variación geográfico asociado a la morfología del diente. En las últimas décadas se ha generado una notable producción científica en torno al estudio de los rasgos dentales no métricos con el fin de definir los patrones geográficos de los grupos, su historia, origen o estructura, entre otros. Entre las aplicaciones propuestas está la posibilidad del uso de la frecuencia de los diferentes rasgos de expresión en un contexto forense. Se presenta una revisión de la literatura en las bases MEDLINE, SciELO, REDALYC y LILACS. Se incluyeron artículos completos, en español, portugués e inglés, que realicen análisis de rasgos morfológicos dentales en poblaciones sudamericanas actuales (siglos XX y XXI). Los artículos seleccionados fueron evaluados por dos investigadores de manera independiente. Las estrategias de búsqueda permitieron pesquisar 36 estudios con una importante participación de Colombia (tanto en autores como en muestreos), seguida por Chile y Brasil. Si bien estos resultados demuestran una robusta actividad en el ámbito de la antropología dentaria Sudamericana estudiando poblaciones actuales, se sugiere una reevaluación de las metodologías empleadas si se pretende asignar un valor forense a los rasgos dentales morfológicos.

In recent human populations there is a pattern of geographic variation associated to the tooth morphology. In the last decades there has been a remarkable scientific production around the study of non-metric dental traits in order to define the geographic patterns of groups, their history, origin or structure, among others. Between the proposed scopes is the possibility of using the frequency of different traits of expression in a forensic context. We present a review of the literature in MEDLINE, SciELO, and LILACS and REDALYC databases. Full articles in Spanish, Portuguese and English conducting analyzes of dental morphological traits in present South American populations (XX and XXI centuries) were included. Two researchers evaluated the selected articles independently. The search strategies allowed identified 36 studies with a significant participation of Colombia (both authors and samples), followed by Chile and Brazil. While these results demonstrate a robust activity in the field of dental anthropology studying South-American present populations, a reevaluation of the methodologies is suggested if it is to assign a forensic value to dental morphological traits.

Desarrollo de la investigación sobre variación morfológica de poblaciones históricas sudamericanas utilizando rasgos dentales no métricos / Development of research on morphological variation of historical South American populations based on non-metric dental traits

El análisis de rasgos no métricos dentales ha logrado establecer relaciones biológicas de grupos humanos pasados y actuales con un alto valor taxonómico. Aunque Sudamérica ha sido objeto de un número considerable de investigaciones sobre poblamiento, migraciones y mestizaje, son relativamente pocos los estudios que han utilizado información de rasgos dentales para este fin, con las consiguiente ausencia de datos en amplias zonas geográficas. Se realizó una revisión sistemática de la literatura en MEDLINE, SciELO, REDALYC y LILACS, sin restricción de fecha de publicación. Se incluyeron artículos completos y disponibles primarios y secundarios en español, inglés y portugués donde se realice el análisis de rasgos morfológicos dentales en poblaciones sudamericanas con un contexto histórico anterior al siglo XX. Los artículos seleccionados fueron evaluados por dos investigadores de manera independiente. La búsqueda arrojó 2210 artículos de los cuales 19 cumplieron los criterios de inclusión, a los que se agregaron 9 luego de una búsqueda manual complementaria. Existe un desarrollo no equilibrado de la investigación sudamericana, tanto en el foco geográfico donde esta se realiza, como de los países y filiaciones de sus autores. Aunque se han logrado estandarizar los instrumentos de valoración de esos rasgos, se sugiere promover una profesionalización interdisciplinaria, el apoyo internacional de sus proyectos y el abordaje holístico de sus contenidos para potenciar la aplicabilidad de su valor taxonómico a poblaciones actuales.

Studies of non-metric dental traits have managed to estimate biological relationships among ancient and contemporary human groups with a high taxonomic value. While South America has been subject of considerable research on settlement, migration and miscegenation, only a few studies have used information from dental traits for this purpose, with the consequent absence of data over wide geographical areas. A systematic review was conducted of the literature in MEDLINE, SciELO, REDALYC y LILACS, without limiting publication date. Full primary and secondary articles available in Spanish, English and Portuguese were included, where dental morphological traits were used to analyze South American populations with a historical context prior to the twentieth century. The selected articles were evaluated by two researchers independently. The search revealed 2210 articles, of which 19 met the inclusion criteria, which added 9 after a complementary manual search. There is an unbalanced development of the South American research, both in geographical focus where this is done, as countries and affiliations of the authors. While there has been standardized instruments valuation of these traits, it is suggested to promote an interdisciplinary professionalization, the international support of its projects and the holistic approach of its content to enhance the applicability of their taxonomic value to contemporary populations.

Características morfológicas métricas y no métricas del esternón del individuo mapuche / Metric and non-metric morphological traits of the sternum in mapuche

El objetivo fue describir las características morfológicas métricas y no métricas del esternón de individuos Mapuche de sexo masculino y comparar estos parámetros con otras poblaciones del mundo. Se realizó un estudio descriptivo sobre 50 esternones secos de individuos Mapuche adultos de la región de la Araucanía, Chile, con edades comprendidas entre los 20 y 84 años. La longitud del esternón se midió en milímetros como la distancia combinada del manubrio y el cuerpo del esternón desde la incisura yugular a la unión xifoesternal, junto a la longitud del manubrio y cuerpo del esternón de manera independiente a lo largo del plano mediosagital. Para el proceso xifoides, se determinó también su longitud, ancho y grosor. Las características no métricas como forma y presencia de forámenes fueron observadas y registradas en cada caso. La longitud media del esternón fue 186,2±20,6 mm, del manubrio49,97±13,68 mm y del cuerpo esternal 98,90±13,40. El mayor grosor y ancho se observó en el manubrio 14,37±1,76 mm y 62,80±5,67, respectivamente, seguido por el cuerpo esternal. El proceso xifoides mostró las menores dimensiones tanto en largo, ancho y grosor. Se observaron forámenes esternales (8%) y xifoideos (12%), y la forma bífida y de paleta fueron las más comunes en el proceso xifoides. La morfología del esternón permiten caracterizar rasgos antropológicos y forenses de tipo población-específica. Los rasgos métricos como la longitud combinada del esternón, podrían ser utilizados para discriminar sexo y estimar la estatura en el individuo Mapuche, mientras que los no métricos pueden ser relevantes para determinar variaciones biológicas, estimar edad o aspectos de interés clínico en la población Mapuche.

The aim was to describe the metric and non-metric morphological traits of the sternum in Mapuche males and to compare these parameters with other world populations. A descriptive study on 50 dry adult Mapuche male individuals Sterna from the region of Araucania, Chile, aged between 20 and 84 years were reviewed. The length of the sternum was measured in mm as the combined length of the manubrium and body of the sternum from the incisura jugularis to the mesoxiphoid junction, and manubrium and body of the sternum independently along the midesagittal plane. To the xiphoid process , was also determined length, width and thickness. The non-metric features such as shape and presence of foramina were observed and recorded in each case. In the sternum, mean length was 186.2±20.6 mm, in the manubrium 49.97± 13.68 mm and for the body of the sternum was 98.90 ± 13.40. The greater thickness and width was observed on the manubrium 14.37±1.76 and 62.80±5.67 mm, respectively, followed by the body of the sternum. The xiphoid process showed the smaller both in length, width and thickness. Sternal and xiphoid foramina was observed in 8% and 12%, and bifid and paddle shape were the most common observed in the xiphoid process. The morphology of the sternum allows forensic anthropological and characterize features in a specific population. Metric traits as the combined length of the sternum, could be used to discriminate sex and estimate the height in the individual Mapuche, while non-metric may be relevant to determine biological variation, estimating age or aspects of clinical interest in the Mapuche population.

Morphometric Analysis of the Skull by Moire Contourography / 체질인류학회지

The non-metric analysis of the skulls is very useful for estimating sex and determination of ancestry, the accuracy tends to depend on the amount of experiences of the observers, and so inter-observer errors might be happened. Many researchers are trying to find out more objective methods for determination of ancestry. The purpose of this presentation is to show the usefulness of moire contourography for analyzing the skull. The master screen that is similar to the gratings was made by steel rods, which were arranged as equally spaced parallel lines. Halogen light source was illuminated by lantern slide projector. The skeletal materials were documented crania, composed of 87 male and 47 female, from William M. Bass Donated Skeletal Collection housed at the Department of Anthropology, University of Tennessee. The skulls were placed just behind the master screen as anatomical position using cubic craniophore. The angle between the light source and camera was 65degrees, the distance between camera and the master screen was 1.2 m. Frontal view, left lateral and right lateral view were taken. From the frontal view, fringe patterns were analyzed for first five contour lines which were mainly located around the Glabella. The results were as followed; Type I for male was 53% and female was 4%; Type II for male was 29% and female was 2%; Type III for male was 2% and female was 15%; Type IV for male was 6% and female was 55%. From the lateral view, fringe patterns were analyzed for first four contour lines. However, first and second contour lines were critical to determine the shape and the results were as followed; Type I for male was 52% and female was 22%; Type II for male was 38% and female was 26%; Type III for male was 8% and female was 17%; Type IV for male was 2% and female was 35%. According to this study, different fringe patterns might be dependent on the degree of development of bone marker such as Glabella, Supercillary arch, Euryon and Mastoid process. For example, Supercillary arches were very well developed and slope of forehead above the Glabella was declined, fringe pattern showed reverse triangle shape. If Supercillary arches were poorly developed and slope of forehead above the Glabella was flat, fringe pattern showed home plate shape. The present research shows that moire contourography might be used as more objective methods for estimating sex. And it would be helpful to determine the ancestry when the lateral aspects were analyzed. In the future, continuing study need to be performed with same master screen for different ancestry.

Revisión del rasgo premolar Uto-Azteca en Sudamérica y su presencia en Colombia / A review of the Uto-Aztecan premolar trait in South America and its presence in Colombia

Introducción: el rasgo denominado premolar Uto-Azteca (en adelante PUA) o cresta disto-sagital de los premolares superiores es una variante morfológica muy rara que aparece únicamente en los primeros premolares superiores permanentes de los grupos indígenas americanos. El rasgo PUA se describe como la presencia de una cresta pronunciada que va desde el ápice de la cúspide bucal (paracono) y se extiende hacia el borde disto-oclusal llegando muy cerca del sulcus sagital. El objetivo de esta investigación fue describir la presencia de PUA en Sudamérica y su relación con poblaciones indígenas de Colombia. Métodos: se compilaron 495 individuos registrados en la literatura. Se aplicó estadística convencional descriptiva para observar asimetría y variables atípicas. Luego se hizo una comparación usando la medida media de divergencia de Smith. Resultados: la dispersión de este rasgo en Sudamérica pudo deberse a una interacción entre los grupos representados por dos componentes biológicos observados en la matriz calculada. Discusión: la costa del océano pacífico y los valles interandinos que conectan Andes y Amazonia junto con sus ríos principales debieron desempeñar un papel primordial en la rápida dispersión de este rasgo en muestras tan distanciadas como Minas Gerais (Brasil) y Punta Teatinos (Chile). Conclusiones: el rasgo PUA está presente en Colombia a partir del 3.000 AP aproximadamente. Es necesario observar este rasgo en grupos mestizos.

Introduction: the so-called Uto-Aztecan premolar (hereinafter UAP) or distal-sagittal crest of upper premolars is a rare morphologic trait that appears in the first premolars of American Indian groups only. It is described as the presence of a pronounced crest extending from the tip of the buccal cusp (paracone) towards the distal-occlusal edge, almost reaching the sagittal sulcus. The objective of this study was to describe the presence of UAP in South America and its relation with Colombian indigenous populations. Methods: a total of 495 individuals recorded in the literature were collected. Conventional descriptive statistics was used to observe asymmetry and atypical variables. Comparisons were made using Smith’s mean measure of divergence. Results: the spreading of this trait in South America might have been due to interactions between the groups represented by two biological components observed in the calculated matrix. Discussion: the Pacific Ocean coast and the valleys that connect the Andean and Amazonian regions coupled with their main rivers should have played a role in the rapid spread of this trait in samples located as far apart as Minas Gerais (Brazil) and Punta Teatinos (Chile). Conclusions: UAP is present in Colombia since about 3000 BP (before present). This trait should be evaluated in mestizo groups.

Hemoglobin polymorphism and morphometrical correlates in the west african dwarf sheep of Nigeria / Polimorfismo de la hemoglobina y correlaciones morfométricas en la oveja enana del oeste áfricano en Nigeria

Red cells extracted from blood samples taken by jugular venipuncture from a total of thirty-six traditionally managed adult West African Dwarf rams and ewes were subjected to starch gel electrophoresis, stained to reveal the activities of different allelemorphs at hemoglobin locus and analyzed. The studies was aimed at examining genetic variation as well as pattern of segregation at the locus and unveil possible association that might exist between the phenotypes and selected zoometrical traits. From the three theoretically phenotypes expected to be produced in the population by the two co-dominant alleles identified, only two: HbAA and HbAB were observed. The observed genotype frequencies conformed to Hardy-Weinberg's equilibrium. Proportion of polymorphic loci was 10.10 percent while heterozygosity (H) was 0.218. Investigation showed that the Mendelian segregation at the loci tested was not congruent with investigated quantitative traits vis-à-vis horn and hair lengths tested. The hemoglobin phenotypes are independent of the traits tested.

Hematíes extraídos de muestras de sangre tomadas por punción venosa yugular de un total de treinta y seis carneros y ovejas enanas del oeste Áfricano, tradicionalmente manejadas como adultos, fueron sometidos a electroforesis en gel de almidón, y analizados mediante tinción para revelar las actividades de los morfoalelos en los diferentes locus de la hemoglobina. El objetivo del estudio fue examinar la variación genética, así como el patrón de segregación en el locus, y develar la posible asociación que puede existir entre los fenotipos y los rasgos zoométricos seleccionados. De los tres fenotipos teóricamente esperados a ser producidos en la población por los dos alelos co-dominantes identificados, sólo dos: HbAA y HbAB fueron observados. Las frecuencias genotípicas observadas se conformaron de acuerdo al equilibrio de Hardy-Weinberg. La proporción de locis polimórficos fue 10,10 por ciento, mientras que la heterocigosidad (H) fue 0,218. La investigación mostró que la segregación mendeliana en los loci probados no fue congruente con los rasgos cuantitativos investigados vis-à-vis de longitud de cuernos y pelo. Los fenotipos de hemoglobina son independientes de las características de la prueba.

Dental non-metric traits in a pre-conquest sample "Calchaquí" from Argentina, South America / Rasgos dentales no-métricos en una muestra pre-conquista "Calchaquí" de Argentina, América del Sur

The present study was carried out with a Calchaquí human Pre-Conquest sample from Northwest of Argentina, with the aim of exploring the dental morphology patterns in this population. This study was carried out by means of a macroscopic analysis in permanent dentitions of 7 skulls. 40 dental non-mtetric traits were recorded using the ASU Dental Anthropology System. Percentages >70 percent was found only in 4 traits. Calchaquí sample studied here is near to these values in shovel shape expression, but the results of this study suggest that a Sinodont pattern is no clear for this sample. To conclude, the present investigation provides additional, insightful elements for a description of biological factors in the process of dental morphologic diversification associated to regional and temporal ranges in this region of Argentina.

Estudiamos una muestra Pre-Conquista de Calchaquíes del Noroeste de Argentina, con el objetivo de explorar patrones de morfología dental presentes en esta población. Se realizó un análisis macroscópico en dentición permanente de 7 cráneos. 40 rasgos no-dentales fueron registrados utilizando el ASU Dental Antropology System. Porcentajes mayores al 70 por ciento fueron encontrados solamente en 4 rasgos. La muestra estudiada está cerca de valores en la expresión de la forma de pala, pero los resultados de este estudio sugieren que un patrón Sinodonte no es claro para esta muestra. Para concluir, la presente investigación brinda adicionalmente, profundos elementos para una descripción de los factores biológicos en el proceso de diversificación morfológica dental asociada a los rangos regionales y temporales en esta región de Argentina.

Topography of the Inferior Wall of the Maxillary Sinus in Koreans / 체질인류학회지

The anatomical description and the relationship between the root apex and the inferior wall of sinus are critical in diagnoses and surgeries of the sinus pathoses, and in dental implantation. So, identification of the proximity between the root apex and the inferior wall of sinus and the clarification of cortical thickness of inferior wall of sinus are indicated the topography of spreading dental infection into the maxillary sinus. Therefore, anatomical knowledge of the topography between the root apex and the inferior wall maxillary sinus are important in the diagnosis and treatment planning of the dental implantation, endodontic procedures, and orthodontic treatment. The purposes of this study were to clarify the morphological and clinical characteristics of the maxillary sinus, especially the inferior wall of sinus in Korean, and to identify the relationship between the inferior wall of maxillary sinus and the roots of maxillary teeth. 24 sides of maxillae of the hemi -sectioned Korean heads were used in this study. All specimens were taken DentaScan reformatted cross -sectional images were taken for the radiographic evaluation of the maxillary teeth and inferior wall of maxillary sinus. All specimens were decalcificated and thenp were sectioned coronally. On the sectioned specimen, 21 metric items were measured using the image analyzing system. The results were as follows: 1. The distance between the each root apex and the inferior wall of maxillary sinus were measured. In the 2nd molar area the distance from the root apex to the inferior wall of sinus was the shortest and the longest in the 1st premolar area. 2. The thickness of the cortical plate of the inferior wall of maxillary sinus was thinnest in the 1st premolar area, whereas, the thickest in the 2nd premolar area. 3. The vertical relationship between the inferior wall and the roots of the maxillary molars was classified into 5 types. Type I (the inferior wall of sinus was located above the level connecting the buccal and lingual root apices) was predominant (54.5% in the 1st molar area, 52.4% in the 2nd molar area). 4. The horizontal relationship between the inferior wall of sinus and root apex were classified into 3 types. Type 2 (the alveolar recess of the inferior wall of sinus was located between the buccal and lingual roots) was predominant (80% in the 1st and 2nd molar area). Taken all together, this study demonstrated various anatomical characteristics and relationships between the maxillary sinus and their surrounding structures. Recognition of these findings may have an impact on the clinical management of patients.

Non-metric Traits of Korean Mandibles / 체질인류학회지

Mandible is the biggest and the hardest facial bone and its shape is found well-remained in the fossil and forensic research area. Therefore it is of significance in physical anthropology and it has been used to distinguish the different ethnic groups as well as the sex. The researchers took 102 mandibles in Korean of the known sex and examined the physical anthropologic characteristics that exist among the Korean males and females as well as the different ethnic groups. Through examining 13 criteria that include the shape of the chin and the shape of mental spine the following results were achieved. Out of the 13 non-metric criteria of the examined mandibles, Concerning the sexual dimorphism, the most distinguished criteria was the contour of the mandibular lower border. In males, 68.1% showed the "rocker form", on the other hand in females, the "straight form" was more general (82.0%). In addition, the shape also differed in mental region. In males the shape of the chin was bilobate or square form generally (91.7%), while females' mandible wasn't bilobate form, but square (53.6%) and pointed form (46.4%). Beside this, there was no differences between the male and female. We compared in presence of mylohyoid canal in Korean with the other ethnic groups by non-metric traits. The mylohyoid canal was relatively low by 5% among the Asians including the Koreans and relatively high by 10.0% among the Whites and over 15.0% among the Blacks.

Non-metric Dental Traits in Koreans and Its Racial Differences / 체질인류학회지

Since the non-metric traits of the human teeth are various according to the genetic or environmental factors, these dental traits are significantly used in distinguishing the different racial groups. The purpose of this study was to evaluate the non-metric dental traits of Koreans among the various races on the viewpoints of the physical anthropology. The materials of this study were conducted with incisors, canine, and molars collected from 168 Korean cadavers and the upper and lower dental models of 160 Koreans. We evaluated the 15 criteria of the non-metric dental traits of Korean teeth. The results were as follows. 1. Most of the Koreans' maxillary incisors were revealed to the shovel-shaped incisor, whereas, none of the mandibular incisors showed the shoveling. The double shoveling of the maxillary central incisors and the lateral incisors were observed in 31.2%, 7.6%, respectively. The presence of the shoveling of Korean maxillary incisors was the most compared to the other racial groups. 2. The peg lateralis were only seen in the maxillary lateral incisor by 10.2%. 3. It showed a relatively low rate in the presence of the distal accessory ridge of the canine and it was more commonly seen in the maxillary canine than in the manibular canine. 4. It was most common that the maxillary molar had 4 cusps (maxillary 1st molar: 96%, maxillary 2nd molar: 81.7%). On the other hand, mandibular 1st molars having 5 cusps were most common in 81.1% and mandibular 2nd molar having 4 cusps was most common in 52%. 5. The cusp-groove patterns of the maxillary molar occlusal surface were classified into 4 categories. Among these categories, "4" patterns were most in the maxillary 1st molars and "4-" patterns were most in the mandibular 2nd molars. 6. Carabelli's trait was mostly observed in the maxillary 1st molar and "high cone patterns" among the Carabelli's traits were shown in 9.9% Korean males. The presence of the Carabelli's trait was much lower than the Caucasian. 7. The cusp-groove patterns of the mandibular molar were classified into 4 categories. The presences of "Y5" pattern (45.6%) and "+5" pattern (51.6%) were equally observed in the mandibular 1st molars, while the "+" patterns ("+4" pattern : 46.3%, "+5" pattern : 40.0%) were most in the mandibular 2nd molars. From these results, the presence of "Y5" patterns in the Korean mandibular molars were lower, but it had a tendency that presence of "+5"patterns was higher than the other races. 8. The cases in which "cusp 6" was observed in the mandibular 1st molar and 2nd molar were 5.3%, 5.1%, respectively. And the presences of "cusp 7" were observed in the mandibular 1st molar and 2nd molar by 7.5%, 4.1%, respectively.

Metric and Non-metric Traits of the Teeth in Past and Present Koreans / 체질인류학회지

Teeth play an important role in mastication and phonation as well as in esthetics. Since metric and non-metric characteristics of teeth can be used in anthropological comparison, archeology and identification, they are very important in physical anthropology, archeology and forensic odontology. However, this subject has rarely been studied in Koreans and therefore data on the anthropological characteristics are scarce. Researchers have measured 5 factors on each tooth and 9 non-metric characteristics of 1085 teeth collected from Gaya, Korea and Chosun people and 1397 teeth collected from the present Koreans (both female and male). Metric and non-metric traits of the teeth were compared in past and present Koreans. Comparing the measurement of the teeth in past and present Koreans, no difference in the faciolingual diameter was seen while slight difference was seen in the mesiodistal diameter of past and present Koreans. Non-metric traits of Koreans showed that 96.4% of past Koreans and 94.2% of present Koreans had shoveling in the maxillary central incisior while 93.1% of past Koreans and 90.6% of present Koreans had shoveling in the maxillary lateral incisor. Therefore shoveling was present in a higher rate in the past Koreans. The result on the comparison of the lingual cusp number on mandibular second premolars, showed that while past Koreans had 1 (48.0%) or 2 (52.0%) lingual cusps, present Koreans had 1 (52.3%), 2 (46.7%) or 3 (1.0%) lingual cusps. The Terra's tubercle was seen on the mesial surface in 53.7% of maxillary first premolar in the present Koreans and 48.7% of maxillary second premolar showed no tubercle. Meanwhile, past Koreans showed a higher rate of Terra's tubercle than present Koreans. Frequence of Carabelli's tubercle in the maxillary first molar was 18.4% in past Koreans and 36.2% in present Koreans. The most common form of occlusal groove pattern in the maxillary first molar was '4' (94.3% in past Koreans, 94.3% in present Koreans) and in the maxillary second molar was '4-' (40.5% in past Koreans, 76.5% in present Koreans). In both the past and present Koreans, The 'Y5' pattern of occlusal groove pattern was most common in the mandibular first molar and '+4' pattern in the mandibular second molar.