Statistical Analysis of Neohelos Dental Measurements
نویسنده
چکیده
Length and width measurements of the cheek teeth of the mid-Tertiary Australian diprotodontoid Neohelos from three areas have been analysed statistically. The three areas were Lake Ngapakaldi, South Australia; Bullock Creek, Northern Territory; and Riversleigh, Queensland. Measurements of individual features were compared between populations of Neohelos from different localities utilising Student's t-test. These outcomes were subsequently summarised utilising means of the t-test values as the basis for assessing the degree of similarity between population pairs. This information was then expressed graphically by means of a dendrogramme showing the clustering of populations on the basis of the relative degree of similarity. This mode of analysis is based solely on size and proportional differences in tooth measurements between populations. As such, its weakness in that two quite unrelated taxa would be judged as similar if their tooth dimensions happen to be the same. However, where a difference on this basis is recognised, it is to be anticipated that examination of other, perhaps quite subtle features will corrorborate that different taxa are present. What examination of the dendrogrammes shows is that with two exceptions, the Bullock Creek Neohelos spB material stands quite apart from all other sites. The exceptions are from two sites at Riversleigh: Jaw Junction specimens of Neohelos spC, a species known nowhere else and three teeth of Neohelos spB from Henk's Hollow. It is solely on the basis of qualitative characters that Neohelos spB and Neohelos spC are split apart. Likewise, the Riversleigh Cleft of Ages Neohelos spA material and the single specimen of Nimbadon scottorrorum from the Fig Tree locality at Riversligh both group with one of the two distinct clusters of Riversleigh Neohelos tirarensis populations.
منابع مشابه
Reliability and Validity of Dental Measurements Made on Digital and Stone Orthodontic Models
Introduction: A study model is a precise three dimensional replica of patient’s dentition and plays an important role in treatment planning. Many digital multi-media applications have become available to the clinician and his or her staff to facilitate standard procedures in practice and management. The aim of this study is to evaluate reliability and validity of dental measurement made on dig...
متن کاملThe effect of vocational awareness level on dental anxiety and oral health among the students of dentistry
BACKGROUND AND AIM: The purpose of this study was assessing oral health status and dental anxiety differences between the freshman and senior dental students and the effect of awareness on dental practices. METHODS: Freshman (n =71) and senior dental students (n = 41) were included in this study. All participants were applied ...
متن کاملComparative Analysis of Dimensional Accuracy of Two Types of Silicone Impression Materials: Optosil and Elite-HD
Statement of the Problem: Understanding about impression materials, their properties, uses and manipulation can guide operators towards having more successful restorations. Purpose: The aim of this in vitro study was to compare the accuracy of a condensation silicone impression material, Optosil, and an addition poly siloxane impression material, Elite-HD. Materials and Method: A laboratory mod...
متن کاملThe effect of different needle-insertion depths on the accuracy of the Root ZX II and Root ZX mini apex locators in the presence of various irrigants
BACKGROUND AND AIM: The aim of the present study was to evaluate the effect of different needle-insertion depths on the accuracy of the Root ZX II and Root ZX mini apex locators in the presence of various irrigants. METHODS: Ninety extracted single-canal human teeth were used in nine experimental groups. The coronal one-third of the canals was preflared, and the length to the major foramen was ...
متن کاملRelationship between Anterior Teeth Sizes and Facial Dimensions in Dentate Patients
Background and purpose: Esthetics is a major purpose in prosthetic treatments. Choosing the right size of anterior teeth in prosthetic and edentulous patients is a major challenge for both the patient and the dentist. This study was designed to obtain approximately close ratios for selection of anterior teeth. Materials and methods: This descriptive-analytical study, was performed in 121 pati...
متن کامل