Genetic Correlation, Pleiotropy, and Molar Morphology in a Longitudinal Sample of Australian Twins and Families.

This study aims to expand our understanding of the genetic architecture of crown morphology in the human diphyodont dentition. Here, we present bivariate genetic correlation estimates for deciduous and permanent molar traits and evaluate the patterns of pleiotropy within (e.g.

The genetic architecture of anterior tooth morphology in a longitudinal sample of Australian twins and families.

Objective: This study presents a quantitative genetic analysis of human anterior dental morphology in a longitudinal sample of known genealogy. The primary aim of this work is to generate a suite of genetic correlations within and between deciduous and permanent characters to access patterns of integration across the diphyodont dental complex.

Design: Data were recorded from casted tooth crowns representing participants of a long-term Australian twin and family study (deciduous n = 290, permanent n = 339).

Patterns of heritability across the human diphyodont dental complex: Crown morphology of Australian twins and families.

Objectives: This study generates a series of narrow-sense heritability estimates for crown morphology of the deciduous and permanent dentition with two overarching aims. The first is to test the hypothesis that deciduous teeth provide a more faithful reflection of genetic information than their permanent successors. The second is to use quantitative genetic methods to evaluate assumptions underlying common data collection and analysis practices in biodistance research.

Compensatory interactions between developing maxillary anterior teeth in a sample of twins.

Objectives: The objective of this study was to revisit the topic of compensatory interactions between maxillary anterior teeth during development advanced by Sofaer et al. (1971). We addressed the hypotheses listed by Sofaer and colleagues using data derived from our Australian twin sample to investigate whether final tooth size in permanent maxillary central incisors and canines showed evidence of developmental compensation for adjacent missing or microdont lateral incisors.

Technical note: The use of 3D printing in dental anthropology collections.

Objectives: Rapid prototyping (RP) technology is becoming more affordable, faster, and is now capable of building models with a high resolution and accuracy. Due to technological limitations, 3D printing in biological anthropology has been mostly limited to museum displays and forensic reconstructions. In this study, we compared the accuracy of different 3D printers to establish whether RP can be used effectively to reproduce anthropological dental collections, potentially replacing access to oftentimes fragile and irreplaceable original material.

A simple rule governs the evolution and development of hominin tooth size.

The variation in molar tooth size in humans and our closest relatives (hominins) has strongly influenced our view of human evolution. The reduction in overall size and disproportionate decrease in third molar size have been noted for over a century, and have been attributed to reduced selection for large dentitions owing to changes in diet or the acquisition of cooking. The systematic pattern of size variation along the tooth row has been described as a 'morphogenetic gradient' in mammal, and more specifically hominin, teeth since Butler and Dahlberg.

Sex determination from fingerprint ridge density and white line counts in Filipinos.

Fingerprints are distinct physical characteristics that remain unchanged throughout an individual's lifetime. This study derived Filipino-specific probability formulae from fingerprints to be used for sex discrimination in human identification cases. Ridge density from three different areas - distal radial area, distal ulnar area, and proximal area - as well as white line counts from fingerprints of 200 male and 200 female Filipinos were collected and analyzed statistically.

Three-dimensional profilometric assessment of early enamel erosion simulating gastric regurgitation.

Objectives: A priority research area in minimal intervention dentistry is the characterization of the early stages of dental erosion. The aim of this in vitro study was to assess the effect of short, repetitive erosive challenges to human enamel over 2 min at pH 1.5 and 3.

Applied anatomy of the lingual nerve: relevance to dental anaesthesia.

Objectives: (1) to classify the external morphology of the lingual nerve and investigate any relationship between its external and internal morphology, (2) to explore the fascicular structure, nerve tissue density and capillary density of the lingual nerve, and (3) to provide an anatomical explanation as to why adverse clinical outcomes more commonly affect the lingual nerve following local dental anaesthesia. Where possible, comparisons were made between the lingual and inferior alveolar nerves.

Materials And Methods: The lingual and inferior alveolar nerves were examined in 23 hemi-sectioned heads macroscopically and microscopically 2mm above the lingula.

Odontometric sex variation in Malaysians with application to sex prediction.

Information about the sex of individuals is important for human identification. This study was conducted to quantify classification rates of sex prediction models for Malaysians using odontometric profiles. Mesiodistal (MD) and buccolingual (BL) crown dimensions of the permanent dentition were studied in 400 young adult Malaysians, giving a total of 28 tooth size variables.

Dento-facial relationships in individuals with normal occlusion.

The aim of this study was to evaluate the relationships of selected facial measurements with mesio-distal crown widths and dental arch dimensions in individuals with normal occlusions. A cross-sectional study was conducted on 276 subjects with Angle's Class I normal occlusions. Three-dimensional images of the face and dental casts were captured and analyzed using stereophotogrammetric systems.

Genetic, epigenetic, and environmental influences on dentofacial structures and oral health: ongoing studies of Australian twins and their families.

The Craniofacial Biology Research Group in the School of Dentistry at The University of Adelaide is entering an exciting new phase of its studies of dental development and oral health in twins and their families. Studies of the teeth and faces of Australian twins have been continuing for nearly 30 years, with three major cohorts of twins recruited over that time, and currently we are working with twins aged 2 years old to adults. Cross-sectional data and records relating to teeth and faces of twins are available for around 300 pairs of teenage twins, as well as longitudinal data for 300 pairs of twins examined at three different stages of development, once with primary teeth, once at the mixed dentition stage, and then again when the permanent teeth had emerged.

An anthropological perspective: another dimension to modern dental wear concepts.

For many years, research on tooth wear by dental academics has been diametrically opposite to that of anthropological research, with each discipline having a different understanding as to the nature of the wear processes. Dental focus revolved around preventive and restorative considerations while the anthropological focus was a biological understanding related to human evolution, diet, environment, form, and function and included all the craniofacial structures. Introducing the anthropological perspective into modern dentistry gives an insight into the "bigger picture" of the nature and extent of tooth wear.

Validity and reliability of tooth size and dental arch measurements: a stereo photogrammetric study.

Background: The development of three-dimensional computer imaging has many applications in dentistry, including the analysis of dental casts.

Aims: To assess the validity and reliability of a dental stereophotogrammetric imaging system.

Methods: The sample consisted of 35 sets of dental costs.

Stereophotogrammetric analysis of nasolabial morphology among Asian Malays: influence of age and sex.

Objective: It is clear that population-specific norms should be used when planning plastic and reconstructive surgery for selected patients. In this study, we aimed to generate nasal and labial reference values by applying a stereophotogrammetric technique. A further aim was to investigate the effect of sexual dimorphism, age-related changes, and the interrelation between nasal and labial morphology.

The nasopharynx in infants with cleft lip and palate.

Objective: The purpose of this study was to use three-dimensional computed tomography data and computer imaging technology to assess the skeletal components of the naso-pharyngeal area in patients with cleft lip and palate and to quantify anatomical variations.

Methods: CT scans were obtained from 29 patients of Malay origin with cleft lip and palate aged between 0 and 12 months and 12 noncleft patients in the same age group, using a GE Lightspeed Plus Scanner housed in Hospital Universiti Sains Malaysia. Measurements were obtained using the 'Persona' three-dimensional software package, developed at Australian Craniofacial Unit, Adelaide.

Timing of colonization of caries-producing bacteria: an approach based on studying monozygotic twin pairs.

Findings are presented from a prospective cohort study of timing of primary tooth emergence and timing of oral colonization of Streptococcus mutans (S. mutans) in Australian twins. The paper focuses on differences in colonization timing in genetically identical monozygotic (MZ) twins.

The dead center of the dental curriculum: changing attitudes of dental students during dissection.

The purpose of this study was to investigate changes in dental students' perceptions of professionalism, knowledge, and emotion over the period of dissection in a human anatomy course. Whether human dissection needs to be a part of the modern dental curriculum is often called into question, particularly with the plethora of electronic and other aids available to support the learning of anatomy. The influence of the dissection process on development of professional attitudes and emotional maturity has been studied in medical students, but how dental students react to this part of their education is less well known.

Genetic modeling of primary tooth emergence: a study of Australian twins.

The aim of this study was to quantify contributions of genetic and environmental factors to variation in timing of emergence of the primary teeth in a sample of monozygotic and dizygotic twins, using univariate model-fitting approaches. The sample comprised 94 pairs of monozygotic twins and 125 pairs of dizygous twins, all of European ancestry, aged from 2-6 years. Tooth emergence timing was based on parental report, with a subset of data validated by clinical assessment.

Enamel hypoplasia in the primary dentition of monozygotic and dizygotic twins compared with singleton controls.

Background: The study of enamel hypoplasia (EH) and opacity in twins provides insights into the contribution of genetic and environmental factors in the expression of enamel defects.

Aim: This study examined prevalence and site concordance of EH and opacity in the primary dentition of 2- to 4-year-old twins and singleton controls to assess the relative contribution of genetics and the environment to the aetiology of these defects.

Design: The study sample consisted of 88 twin children and 40 singletons aged 2-4 years of age.

A controlled study of dental erosion in 2- to 4-year-old twins.

Background: Dental erosion (DE) in children is a significant oral health issue and has become a focus for research in clinical paediatric dentistry.

Aim: This study investigated DE in the primary dentition of 2- to 4-year-old twin and singleton children with regard to the genetic, medical and dietary factors associated with the condition.

Design: The 128 subjects consisted of 88 twin children (31 monozygous, 50 dizygous, 7 unknown zygosity) and singletons (n = 40) aged 2-4 years.

An odontometric study of the maxillary molars in Australian marsupials. I. The koala (Phascolarctos cinereus).

Crown dimensions of the maxillary molars were measured in the koala (Phascolarctos cinereus). There were no significant differences in crown diameters between the first and second molars, however the fourth molars were reduced in all crown diameters. The third molar was smaller than the first or second molars in buccolingual crown diameters but there were no significant differences in mesiodistal crown diameters.

An evaluation of maxillary and mandibular rotational responses with the Clark twin block appliance.

Aims: To evaluate the dentofacial changes and growth rotational responses of Angle Class II division 1 patients treated with the Clark twin block functional appliance.

Method: This retrospective study comprised 13 boys (8.77 +/- 0.

The effect of CPP-ACP on enamel wear under severe erosive conditions.

Objective: In addition to its role as a remineralizing agent in preventing dental caries, recent evidence has shown that casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) can protect teeth against erosion. The aim of this study was to determine whether CPP-ACP could reduce enamel wear rates under severe erosive conditions simulating heavy attrition and gastric regurgitation.

Design: Enamel specimens were subjected to 10,000 wear cycles at a load of 100 N and pH 1.

An evaluation of head position and craniofacial reference line variation.

Natural head position (NHP) is the usual, balanced position of the head which is adopted for viewing the horizon or an object at eye level. Determination of NHP is useful when reconstructing facial form in art, forensics, orthodontic diagnosis and treatment planning for surgical management of craniofacial dysmorphic conditions. When NHP is uncertain, correction such as orientation to Frankfurt horizontal (FH) has been advocated.