# Geometric Morphometric Shape Analysis of Mandibular Post-Canine Dentition
## 1 Introduction  
The shape of teeth is a fascinating subject that is influenced by a variety of factors. Genetics, environment, and epigenetics all play roles in determining the shapes of an animal's teeth [1]. From a genetic perspective, the shapes of an animal's teeth can reveal its genealogical relationship to other animals. Environmental factors, such as diet, can also have significant impacts on tooth form. Finally, epigenetics can contribute to variations in tooth shape within a species, or even within a single individual [1]. Understandingthe factors that influence tooth form is important for a variety of reasons. It can help us to better understand the evolution of different species, and how they are related to one another. It can also help us to understand the impact of diet on tooth health, and how we can improve our own dental health. By studying tooth form, we can gain a deeper understanding of the complex interplay among genetics, environment, and epigenetics in shaping the natural world.  
Quantifying and analyzing the shapes of morphological structures has long been a challenge for researchers. However, new methods have been developed to tackle this issue, including techniques for acquiring outline and landmark data. Outline methods involve digitizing points along the outline of a structure and fitting them using mathematical functions [2]. On the other hand, landmark-based geometric morphometric methods can be applied to the 2D or 3D coordinates of biologically defined landmarks [3; 4; 5]. Procrustes analysis is a popular technique that superimposes landmark configurations using least-squares estimates for translational and rotational parameters. In recent years, procrustes analysis has been used to analyze the buccal and occlusal shapes of human teeth, resulting in the illustration of the mean shape of teeth [6; 7]. These landmark-based methods provide a deeper understanding of shape variations within a species and offer insights into the evolution of phenotypes. Overall, these new methods have revolutionized the way researchers analyze morphological shape, allowing for more accurate and detailed studies of biological structures [1; 8].  
The study of human dentition is a complex and fascinating field that has garnered significant attention over the years. Researchers have conducted numerous investigations to determine the mode of inheritance for various dental characteristics, using metric analyses by measuring tooth dimensions (odontometry), ratios (tooth indices), as well as non-metric dental traits. Despite extensive research, there are still differing opinions on the role of linked genes in the formation of tooth size and shape. While some studies have suggested that X-linked genes play a role in size development [9; 10], others have demonstrated that a linkage model is not necessary to explain the observed dimorphism [11; 12; 13].  
The purpose of this study was to investigate the relationship between tooth shape and sex. By examining the dental casts of individuals from the Dakshina Kannada region, we hoped to gain insight into the variation in shape of the mandibular post-canine dentition. This research has the potential to identify landmark variations that would define morphology for tooth restoration and human identification in this region and beyond. The aim of this study was to examine the changes in geometric and anatomic landmarks and, thus, the three-dimensional shape of the mandibular post-canine dentition, using 3D geometric morphometric analysis. Further, we aimed to determine the specific landmarks in post-canine dentition that show sexual dimorphism.