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The article discusses various reports on the clinical aspects of dental morphology published within the issue, including one comparing the dental morphology of twins, another on the application of a novel superimposition technique to morphology data derived from measurement of the dental study models of monozygotic co-twins, as well as a report on the modifying effects of the familial genetic contribution in Turner (XO) syndrome.

The associations seen clinically between variations in tooth number, size and shape reflect the repetitive genetic interactions occurring between the epithelium and mesenchyme during the initiation and morphogenetic stages of dental development. The aim of this study was to investigate this relationship further by comparing multiple crown parameters, including cusp numbers, between patients with mild hypodontia and controls. Digital images of dental casts of the permanent dentition from 28 Romanian subjects with mild hypodontia and 28 controls were used. Measurements of the vestibular and occlusal surfaces were performed using a 2D image analysis method. Seven dimensions were measured (mesio-distal, occluso-gingival, bucco-lingual, vestibular perimeter, vestibular area, occlusal perimeter and occlusal area) and cusps on premolars and first molars were counted. Multivariate analysis of variance was performed using SPSS V17 software. The results showed teeth in the hypodontia group were smaller than those of controls, with many measurements being significantly different (significance values varied from p=0.048 to p=0.0001). Lower first incisors and upper first premolar teeth presented the most reduced dimensions. Mesio-distal, bucco-lingual and occlusal area and perimeter dimensions were the most affected. Upper first molars presented the Carabelli trait in significantly less subjects in the hypodontia group than in controls. This variation was accompanied by a difference in tooth height. Lower premolars showed reduced cusp numbers in hypodontia subjects, accompanied by variation in tooth width or depth. In conclusion, this study demonstrated differences in multiple parameters of crown size and shape in patients with mild hypodontia compared to controls. The degree of these differences varied between different tooth types and dimensions. [ABSTRACT FROM AUTHOR]

The article presents information on the growth of Cymbella Sp. which is found growing beneath layers of ice. The reason for the winter growth of Cymbella is linked to aquatic fauna. The absence of active aquatic fauna, which at other seasons of the year browse down algal felts and in many instances keep submerged aquatic macrophytes virtually epiphyte free. Various experimental studies have demonstrated the extent insect larvae and fish can have on the epiphytic flora of various macrophytes. In many instances removal of the algal epiflora from such plants can be rapid and almost complete.

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 3.0 under conditions simulating gastric regurgitation. Methods: Enamel surfaces were subjected to erosive challenges at pH 1.5 (Group 1, n = 10) and pH 3.0 (Group 2, n = 9) for periods of 30 s (stage 1), 60 s (stage 2) and 120 s (stage 3). Quantitative changes were assessed longitudinally by measuring the 3D average surface roughness (Sa) values using 3D confocal microscopy. Qualitative micrographic assessment of surface changes was also conducted by using environmental scanning electron microscopy. Results: Linear mixed model analysis showed significant effects of the pH values ( p < 0.001) and the stages (p < 0.001) on the observed Sa values. Post hoc tests showed significant increases in the Sa values between baseline and other stages in both groups (p < 0.01). The mean Sa values also increased significantly from stage 1 to stage 2 in Group 1 (p < 0.05). Micrographic analysis displayed severely etched enamel rods in Group 1, but only subtle changes in Group 2. Conclusions: The complexity of the enamel surface is influenced by both acid concentration (pH value) and duration of acid exposure during early stages of erosion. Erosion occurring under conditions simulating GORD can be detected in its initial stages, opening up the possibilities of early diagnosis and management of this condition. Clinical significance: Erosive tooth wear occurs progressively and insidiously, often creating complex treatment challenges. This emphasizes the need for early diagnosis and management in accordance with minimal intervention philosophy. Our findings provide a foundation for further research that could lead to the development of highlysensitive clinical diagnostic tools and preventive strategies. [ABSTRACT FROM AUTHOR]

Studies in rodents and humans have suggested that masculinisation of females and feminisation of males can occur between fetuses in utero due to hormonal diffusion. Opposite-sex twin pairs provide a useful model to study the effects of prenatal hormone diffusion on tooth size. The aim of this study is to determine whether primary and permanent tooth size is altered in females and/or males from opposite-sex dizygotic (OSDZ) twin pairs compared with same-sex monozygotic (SSMZ) or dizygotic (SSDZ) twins. Methods: Female sample: 44 OSDZ females, 39 SSDZ females, 52 MZ females; and male sample: 44 OSDZ males, 42 SSDZ males, 56 MZ males; aged from 4.1 to 16.5 years. Serial dental models of primary, mixed and permanent dentitions were used. Mesiodistal (MD) and buccolingual (BL) crown diameters, crown heights (CH) and intercuspal distances (IC) of upper central and lateral incisors, canines, second premolars, first and second molars and lower central and lateral incisors, canines, second premolars, first and second molars were measured to an accuracy of 0.1mm using 2D image analysis system. OSDZ females were consistently larger by approximately 1-3% in MD and BL dimensions for permanent teeth compared with other groups but CH and IC dimensions did not show the same pattern. No systematic trend was found in either dentition of the male groups. This effect may be related to circulating male hormones in utero. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to determine the relative contribution of genetic and environmental factors in the phenotypic variation of the soft tissue facial profile during the mixed dentition and the permanent dentition stages., Methods: In this retrospective cohort study, standardized facial profile photographs of 139 twin pairs (55 monozygotic and 84 dizygotic) were obtained from archival records at the Adelaide Dental School. Photographic analysis used 12 angular and 14 linear facial profile measurements from the mixed dentition (7-11 years) to the permanent dentition (12-17 years) stages. A genetic analysis was performed using a univariate structural equation model adhering to the normal assumptions of a twin model., Results: In the mixed dentition stage, the additive genetic (A) and unique environment (E) model, AE model, was the most parsimonious in explaining the observed phenotypic variance for all 26 facial traits with the narrow-sense heritability estimates ranging between 0.38 and 0.79. In the permanent dentition, the AE model was the most parsimonious for 20 out of 26 traits, however, the variance of six traits, particularly those in the lower third of the face, was best explained by the shared environmental and unique environmental factors., Limitations: This study exclusively included twins of European ancestry., Conclusions: The soft tissue facial profile demonstrated dynamic genetic and environmental influences with a greater additive genetic influence during the mixed dentition and the early stages of the permanent dentition. However, there was evidence of increasing environmental influence in the lower third of the face during the early stages of the permanent dentition., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Orthodontic Society.)

It has been estimated that 25% of monozygotic ("identical") twin pairs exhibit reverse asymmetry (RA) or "mirroring" of minor anatomical features as a result of delayed zygote division. Here, we examine whether identical twin mirroring accounts for patterns of dental asymmetry in a sample of monozygotic and dizygotic ("fraternal") twins. We focus on crown morphology to approach the following question: is there an association between dental RA frequency and twin type suggestive of the presence of mirror image twins in our sample? Data were collected from 208 deciduous and 196 permanent dentitions of participants of the University of Adelaide Twin Study using Arizona State University Dental Anthropology System standards. RA frequencies were compared across morphological complexes (deciduous, permanent), twin types (monozygotic, dizygotic), and traits. Fisher's exact tests were performed to formally evaluate the association between twin type and dental RA. Across the entire dataset, RA rates failed to exceed 8% for any twin type. In monozygotic twins, deciduous mirroring totaled 5.3% of observed cases, while permanent mirroring totaled 7.8% of observed cases. We found no statistically significant association between RA and twin type for any morphological character (p-value range: 0.07-1.00). Our results suggest the timing of monozygotic twin division does not explain the structure of asymmetry for our morphology dataset and that published estimates of identical twin mirroring rates may be inflated or contingent upon phenotype. Instead, rates reported for this sample more closely align with the proposed etiology of this condition., (© 2024 American Association for Anatomy.)

With diagnostic and therapeutic advances, over 80% of children diagnosed with cancer become long-term survivors. As the number of childhood cancer survivors (CCS) continues to increase, dental practitioners become more likely to have CCS among their patients. CCS may develop late complications from damage caused by their cancer treatment to endocrine, cardiovascular, musculoskeletal, and other organ systems. These complications may surface decades after the completion of treatment. Adverse outcomes of childhood cancer treatment frequently involve oral and craniofacial structures including the dentition. Tooth development, salivary gland function, craniofacial growth, and temporomandibular joint function may be disturbed, increasing oral health risks in these individuals. Moreover, CCS are at risk of developing subsequent malignancies, which may manifest in or near the oral cavity. It is important that dental practitioners are aware of the childhood cancer history of their patients and have knowledge of potential late complications. Therefore, this narrative review aims to inform dental practitioners of late oral complications of cancer treatment modalities commonly used in pediatric oncology. Furthermore, selected common non-oral late sequelae of cancer therapy that could have an impact on oral health and on delivering dental care will be discussed.

Background and Objective: The genetic basis of dentoalveolar characteristics has been investigated by several studies, however, the findings are equivocal. The objective of this systematic review and meta-analysis was to evaluate the heritability of dental arches and occlusal parameters in different stages of human dentition., Search Methods: Electronic databases PubMed, Embase, Scopus, Web of Science, and Dentistry and Oral Science Source were searched up to August 2023 without the restriction of language or publication date., Selection Criteria: Empirical studies investigating the heritability of dentoalveolar parameters among twins and siblings were included in the review., Data Collection and Analysis: Study selection, data extraction, and risk of bias assessment were performed independently and in duplicate by two authors and a third author resolved conflicts if needed. Joanna Briggs Institute's critical appraisal tool was used to evaluate the risk of bias among studies and the certainty of evidence was assessed using the Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) criteria., Results: Twenty-eight studies were included in the systematic review, of which 15 studies reporting heritability coefficients in the permanent dentition stages were deemed suitable for the meta-analysis. Random-effects meta-analyses showed high heritability estimates for maxillary intermolar width (0.52), maxillary intercanine width (0.54), mandibular intermolar width (0.55), mandibular intercanine width (0.55), maxillary arch length (0.76), mandibular arch length (0.57), and palatal depth (0.56). The heritability estimates for the occlusal parameters varied considerably, with relatively moderate values for crossbite (0.46) and overbite (0.44) and low values for buccal segment relationship (0.32), overjet (0.22), and rotation and displacement of teeth (0.16). However, the certainty of evidence for most of the outcomes was low according to the GRADE criteria., Conclusions: Based on the available evidence, it can be concluded that the dental arch dimensions have a high heritability while the occlusal parameters demonstrate a moderate to low heritability., Registration: PROSPERO (CRD42022358442)., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Orthodontic Society.)

The aims of this study are to determine the oral health status of a rare sample of 19th-century migrant settlers to South Australia, how oral conditions may have influenced their general health, and how the oral health of this group compares with contemporaneous samples in Australia, New Zealand, and Britain. Dentitions of 18 adults and 22 subadults were investigated using non-destructive methods (micro-CT, macroscopic, radiographic). Extensive carious lesions were identified in seventeen adults and four subadults, and from this group one subadult and sixteen adults had antemortem tooth loss. Sixteen adults showed evidence of periodontal disease. Enamel hypoplastic (EH) defects were identified in fourteen adults and nine subadults. Many individuals with dental defects also had skeletal signs of comorbidities. South Australian individuals had the same percentage of carious lesions as the British sample (53%), more than other historic Australian samples, but less than a contemporary New Zealand sample. Over 50% of individuals from all the historic cemeteries had EH defects, suggesting systemic health insults during dental development were common during the 19th century. The overall oral health of the South Australian settlers was poor but, in some categories, (tooth wear, periapical abscess, periodontal disease), better than the other historic samples.

Objective: Chronic periodontal disease (CP) is a multifactorial infectious and inflammatory disease that occurs due to the challenge between the immune response of the host and specific periodontal bacteria, and that can lead to tooth loss due to damage inflicted to the supporting tissue. The current study investigates the genotypes of the GSTM1 and GSTT1 genes, along with the allelic frequency of the single nucleotide polymorphism [SNP; rs1695] in the GSTP1 gene and correlates them individually or in various combinations with the incidence of CP., Methods: A total of 203 clinically confirmed CP patients and 201 control subjects were enrolled from Multan and Dera Ghazi Khan Districts in Pakistan from April to July 2022. Multiplex Polymerase Chain Reaction (PCR) and tetra-primer amplification refractory mutation system-polymerase chain reaction (T-ARMS-PCR) approaches were applied to determine the genotypes of the studied GSTs. The association of rs1695 in GSTP1 with CP was studied both individually and in various combinations with GSTM1 and T1 ., Results: The absence of GSTM1 , the presence of GSTT1 and the presence of the mutant allele (G) at rs1695 in GSTP1 were found to be significantly associated with CP. Patients aged between 10 and 30 years were more affected by CP., Conclusion: Our results indicate that the genotypes of the analyzed GSTs affect the levels of protection from oxidative stress and may therefore influence the disease progression in CP.

(1) Background: Hypodontia has a multifactorial aetiology, in which genetic factors are a major component. Associated with this congenital absence, the formed teeth may show differences in size and shape, which may vary with the specific genetic variants and with the location of the missing teeth. The aims of the present study were to investigate a specific variant of MSX1 , derive morphometric tooth measurements in a sample of patients with isolated maxillary lateral incisor agenesis and matched controls, and model the findings. (2) Methods: Genotyping of the MSX1 rs8670 genetic variant and morphometric measurements with a 2D image analysis method were performed for 26 hypodontia patients and 26 matched controls. (3) Results: The risk of upper lateral incisor agenesis was 6.9 times higher when the T allele was present. The morphometric parameters showed significant differences between hypodontia patients and controls and between the unilateral and bilateral agenesis cases. The most affected crown dimension in the hypodontia patients was the bucco-lingual dimension. In crown shape there was significant variation the Carabelli trait in upper first molars. (4) Conclusions: The MSX1 rs8670 variant was associated with variations in morphological outcomes. The new findings for compensatory interactions between the maxillary incisors indicate that epigenetic and environmental factors interact with this genetic variant. A single-level directional complex interactive network model incorporates the variations seen in this study.

Objectives: To examine pathological evidence present in a sample of 19th -century settlers to South Australia in the context of an early industrial society., Materials: Skeletal remains of 20 adults and 45 nonadults from the government funded burial site (free ground) of St Mary's Anglican Church Cemetery, gravestones of privately funded burials and local parish records., Methods: Investigation of pathological manifestations of skeletal remains, church records and historic literature. Comparison with similar samples from Britain and from New South Wales., Results: Joint disease seen in 35% of adults. Porosity in bone cortices indicative of vitamin C deficiency seen in 32% of the total sample and porous lesions in the orbit (cribra orbitalia) in 7% of nonadults. Traumatic fractures identified in two adult males. Gastrointestinal conditions were the leading cause of death for nonadults, most adults died of pulmonary conditions. Life expectancy of people buried at the expense of the government was 23.8-42.6 years, those in private burials 57.1 years., Conclusion: Health of migrant settlers from the St Mary's free ground did not differ much from that of a similar population in Britain nor of settlers in New South Wales. Thus, it is characteristic for lower socioeconomic groups in early industrialised societies., Significance: St Mary's sample is a rarity due scarcity of similar Australian skeletal samples., Limitations: Small sample size and lack of similar samples for comparison., Suggestions for Further Research: Comprehensive investigation of dentitions in St Mary's sample and studies of more skeletal samples of early settlers in other Australian locations., (Copyright © 2022 Elsevier Inc. All rights reserved.)

We describe the molecular analysis of three families with hypodontia involving primarily molar teeth and report two novel mutational mechanisms. Linkage analysis of two large families revealed that the hypodontia was linked to the PAX9 locus. These two families revealed missense mutations consisting of a glutamic acid substitution for lysine and a proline substitution for leucine within the paired domain of PAX9. A pair of identical twins affected with hypodontia in a third family demonstrated a 288-bp insertion within exon 2 that resulted in a putative frameshift mutation and a premature stop codon. The insertion was associated with the loss of 7-bp from exon 2. A block of 256-bp of sequence within the insertion was completely identical to downstream sequence from the second intron of the PAX9 gene. These studies extend the spectrum of mutations in PAX9 associated with hypodontia to include heretofore undescribed categories, including missense mutations., (Copyright 2003 Wiley-Liss, Inc.)