Frequency of different groove patterns seen on the occlusal surface of mandibular second premolars

Background: The Mandibular second premolar has commonly three different type traits depending on the occlusal groove patterns. In addition to that they are also recognized on the basis of number of cusps. The objectives of the study were to determine the frequency of different occlusal groove patterns of mandibular second premolars and to acquire base line data for future studies in this population and field of research.Material and Methods: This study was conducted in Islamabad Dental Hospital (IDH), from September 2017 to December 2017. A total of 600 patients (1200 teeth) with fully erupted mandibular second premolars of normal occlusal morphology, in age group of 15 years and above were screened in the Out Patient Department (OPD). Groove patterns on occlusal surfaces and their anatomical variations on both sides i.e. right and left, were observed and noted in a proforma. Data was analyzed using SPSS version 22.Results: Three different patterns of occlusal grooves (Y, U and H) were found in our study population. Y groove pattern was observed in 364 teeth (30.33%), U pattern in 447 teeth (37.25%) and H pattern was noted in 389 (32.41%) teeth. Among males, U pattern was predominant (43.84%) followed by H and then Y pattern. In females, H pattern grooves was found mostly (34.41%), followed by Y and U pattern.Conclusion: The most frequent occlusal groove pattern observed in our population was U followed by H and Y type.

Frequency and Variability of Five Non-Metric Dental Crown Traits in the Primary and Permanent Dentitions of a Racially Mixed Population from Cali, Colombia

The purpose of this study was to determinethe prevalence and variability of five non-metric dentalcrown traits (Carabelli cusp, protostylid, groove pattern,and cusps 6 and 7) in the deciduous (Um2 and Lm2)and permanent (UM1 and LM1) teeth in children inthe mixed-dentition, and to compare these frequencieswith the literature. A descriptive study was conductedto characterize the dental morphology of young subjectsin mixed dentition stages. The Arizona State UniversityDental Anthropology System (ASUDAS) and Grine,Sciulli, and Hanihara methods were used as referenceto compare the prevalence of dental traits in dentalcasts from 100 subjects from a Colombian racially mixedpopulation. The high prevalence of furrows and pits ofthe Carabelli cusp, minor expressions of the protostylid(foramen cecum), and the low frequencies of cusps 5 and6, plus the behavior of the expression of groove patterncollectively suggest that this group reflects influences byboth the Mongoloid and Caucasoid dental complexes.Correspondence of trait expression in both the primaryand permanent dentition was also demonstrated (P< 0.05). Some of the non-metric trait frequencies alsoexhibited sexual dimorphism.

The early polychelidan lobster Tetrachela raiblana and its impact on the homology of carapace grooves in decapod crustaceans

Polychelidan lobsters, as the sister group of Eureptantia (other lobsters and crabs), have a key-position within decapod crustaceans. Their evolutionary history is still poorly understood, although it has been proposed that their Mesozoic representatives largely inhabited shallow-marine environment and only later sought refuge in deep water. This view has recently been challenged, so the evolutionary history of polychelidans is in a need of re-appraisal. The earliest representatives, such as Tetrachela from the Late Triassic of Austria and Italy, are of great importance because of their potential in investigation of life habits of early polychelidans. Tetrachela lived in a relatively deep water, however, its well-developed eyes suggest an environment where light was still present. With its massive dorsoventrally flattened body plan, Tetrachela was probably benthic; the shape of its mandible and stocky first pereiopods suggest it was a scavenger and/or fed on slowly moving or sedentary animals. The carapace of Tetrachela has a peculiar groove pattern, which leads us to redefine some elements of the nomenclature of grooves used for polychelidans. Based on the present revision we propose that the second incision and its associated groove correspond to the hepatic groove, not the postcervical or the branchiocardiac grooves as interpreted previously. This revision allows us to review the homologies of cephalothoracic groove between polychelidans and other notable groups of decapod crustaceans.

Morphological characterization of incisors and molars of an african descent group of Cali, Valle del Cauca (Colombia)

Objectives: To determine the frequency, variability, sexual dimorphism, correlation and bilateral symmetry of 13 non-metric dental crown traits (NMDCT) in incisors and molars of afro descent group of Cali, Valle del Cauca (Colombia)Material and methods: Quantitative cross-sectional study that characterizes the dental morphology of the central and lateral upper incisors (11, 12, 21, 22) and first and second upper and lower molars (16, 17, 26, 27, 36, 37, 46, 47) by ASUDAS system of observation, recording and analysis reported in the literature; from 60 models of study (34 female and 26 male) obtained from a afro descent group with aged between 7 to 17 years.Results: Was obtained winging and crowding mid frequencies, high frequency of shovel-shape in central and lateral incisors, low frequency of Carabelli cusp, low frequency of metaconule, reduction of hypocone absent, P point expression of protostylid, low frequency of deflecting wrinkle, groove pattern configuration Y5 (lower first molar) and +5 and +6 (lower second molar). NMDCT not sexually dimorphic (except hypocone reduction and groove pattern), have low correspondence and have bilateral symmetry. A p<0.05 was considered statistically significant.Conclusions: The frequency and variability of the 13 NMDCT allowed determining that the group of African descent is part of Caucasoid Dental Complex with Mongoloid Dental Complex influence, due to mixing processes and ethno historic settlement of the southeastern region of Cali. Key words: Dental anthropology, dental morphology, incisors, molars, non-metric dental traits, African descent, Afrocolombian.

Cheiloscopic Study among Monozygotic Twins, Non-Twin Brothers and Non-Relative Individuals

This study aimed to investigate cheiloscopic patterns among monozygotic twins (MT), non-twin siblings (NTS) and unrelated individuals (UI). The sample consisted of 20 pairs of monozygotic twins (G1), 20 pairs of non-twin siblings (G2) and 20 pairs of unrelated individuals (G3). Lip thickness, commissures and grooves were evaluated and the latter were classified as: I - clear-cut vertical grooves; I’ - incomplete vertical grooves; II - branched grooves; III - intersecting; IV - reticular grooves and V - undetermined, in 8 labial regions (sub-quadrants). The data were analyzed using descriptive and inferential statistics, with a 5% significance level. Concordance Correlation Coefficient (CCC) and Kappa coefficient, with a 95% confidence interval, were employed to check for agreement rates between G1, G2 and G3 pairs. There was a weak correlation for lip thickness (<0.90) in the total group, with higher values in G1 (CCC from 0.25 to 0.83 and from 0.34 to 0.86, upper and lower lips, respectively), followed by G2 (CCC from -0.03 to 0.70 and from -0.21 to 0.62, upper and lower lips, respectively) and G3 (CCC from -0.25 to 0.56 and from -0.38 to 0.34, upper and lower lips, respectively). With regard to labial commissures, Kappa statistic values were found to be 1.00 for G1, 0.45 for G2 and -0.24 for G3. As for the main groove pattern by sub-quadrant, Kappa values ranged from 0.48 to 0.87 for G1, from 0.17 to 0.59 for G2, and from -0.18 to 0.19 for G3. Monozygotic twins presented a relevant percentage of cheiloscopic agreements. Similarities were also found among NTS, while UI showed greater differences compared to their pairs, highlighting the influence of hereditary relationships on inherited cheiloscopic features.