Before and after: COVID-19 impacts on dental students' well-being, clinical competency and employment opportunities.

INTRODUCTION: The onset of COVID-19 challenged dental schools worldwide, impacting clinical training. In Australasia, New Zealand adopted a COVID-19 'elimination strategy', involving nationwide lockdowns that halted face-to-face education. The 'elimination strategy' adopted at the pandemic onset, which permitted return to 'normal life' in 2021, allowed the pandemic impacts and those related workforce transition to be teased out. This study aimed to evaluate perceived impacts of the COVID-19 pandemic on health and well-being, clinical competency and employment opportunities of dental students. MATERIALS AND METHODS: Two surveys were distributed to final year dental students (n = 94; age range 20-35): one during their final semester and the second six months following graduation. Surveys included open and closed ended questions on participants' self-perceived impacts of COVID-19 on health and well-being, clinical competency and employment opportunities. Average percentages were calculated and descriptive statistics performed. RESULTS: Pre-graduation, participants reported COVID-19 negatively impacted their mental and social health. Slightly lower scores on all dimensions of health post-graduation were likely due to transitioning to the workforce. Pre-graduation, less than half of participants felt prepared to provide the full scope of dental treatment; post-graduation most felt confident to do so. Most participants expected COVID-19 would negatively impact employment opportunities for their cohort, despite all participants being employed when the second survey was conducted. CONCLUSION: Participants self-rated health and clinical competency scores were lower post-graduation when NZ returned to 'normal life', meaning lower scores were related to workforce transition. Dental schools need to be prepared to provide alternative forms of dental education and help mitigate mental health impacts of future major course disruptions.

A new dolphin with tusk-like teeth from the late Oligocene of New Zealand indicates evolution of novel feeding strategies.

All extant toothed whales (Cetacea, Odontoceti) are aquatic mammals with homodont dentitions. Fossil evidence from the late Oligocene suggests a greater diversity of tooth forms among odontocetes, including heterodont species with a variety of tooth shapes and orientations. A new fossil dolphin from the late Oligocene of New Zealand, Nihohae matakoi gen. et sp. nov., consisting of a near complete skull, earbones, dentition and some postcranial material, represents this diverse dentition. Several preserved teeth are horizontally procumbent, including all incisors and canines. These tusk-like teeth suggest adaptive advantages for horizontally procumbent teeth in basal dolphins. Phylogenetic analysis places Nihohae among the poorly constrained basal waipatiid group, many with similarly procumbent teeth. Features of N. matakoi such as its dorsoventrally flattened and long rostrum, long mandibular symphysis, unfused cervical vertebrae, lack of attritional or occlusal wear on the teeth and thin enamel cover suggest the rostrum and horizontally procumbent teeth were used to injure and stun prey though swift lateral head movements, a feeding mode that did not persist in extant odontocetes.

Variation in enamel mechanical properties throughout the crown in catarrhine primates.

Enamel mechanical properties vary across molar crowns, but the relationship among mechanical properties, tooth function, and phylogeny are not well understood. Fifteen primate lower molars representing fourteen taxa (catarrhine, n = 13; platyrrhine, n = 1) were sectioned in the lingual-buccal plane through the mesial cusps. Gradients of enamel mechanical properties, specifically hardness and elastic modulus, were quantified using nanoindentation from inner (near the enamel-dentine junction), through middle, to outer enamel (near the outer enamel surface) at five positions (buccal lateral, buccal cuspal, occlusal middle, lingual cuspal, lingual lateral). Cuspal positions had higher mechanical property values than lateral positions. Middle enamel had higher mean hardness and elastic modulus values than inner and outer locations in all five crown positions. Functionally, the thicker-enameled buccal cusps of lower molars did not show evidence of increased resistance to failure; instead, lingual cusps-which show higher rates of fracture-had higher average mechanical property values, with no significant differences observed between sides. Preliminary phylogenetic results suggest there is relatively little phylogenetic signal in gradients of mechanical properties through the enamel or across the crown. There appears to be common mechanical property patterns across molar crowns in Catarrhini and potentially among primates more broadly. These results may allow more precise interpretations of dental biomechanics and processes resulting in mechanical failure of enamel in primates, such as wear and fracture.

Longitudinal changes in juvenile and adolescent body mass indices before, during, and after the COVID-19 lockdown in New Zealand.

OBJECTIVE: This study uses longitudinal data from school children in Dunedin, New Zealand, to evaluate impacts of COVID-19 lockdown measures on changes in body mass (BMI, kg/m2 ). Impacts are assessed using two non-mutually exclusive hypotheses. The "structured days" hypothesis holds that children tend to alter sleep patterns, reduce activity and increase snacking when not in structured environments. The bidirectional hypothesis proposes that over-weight or obese children are predisposed to further gains in unstructured settings. METHODS: Juveniles and adolescents (n = 95, 60% female) were recruited from Dunedin schools. Repeated measures analyses assessed variation in intra-individual change in BMI during four periods: P1 (before summer break), P2 (during summer break), P3 (during the COVID-19 lockdown), and P4 (after the lockdown ended). The model also examined if these changes were influenced by participants' sex or body size early in the first period assessed using log-transformed BMI, log-transformed weight, height, or lower leg length. RESULTS: Repeated measures analyses of per month gains in BMI (kg/m2 ) during the four periods revealed consistent period (p ≤ .001), period by sex (p ≤ .010), and period by body size (p ≤ .001) interactions across all four body size proxies. Both sexes experienced the greatest gains during the lockdown (P3), but differed in response to their summer break (P2). CONCLUSION: Results are mostly consistent with the "structured days" hypothesis, but challenge the bidirectional hypothesis as defined. Further research better characterizing risks of gains in adiposity are needed.

Phylogenomic Discordance in the Eared Seals is best explained by Incomplete Lineage Sorting following Explosive Radiation in the Southern Hemisphere.

The phylogeny and systematics of fur seals and sea lions (Otariidae) have long been studied with diverse data types, including an increasing amount of molecular data. However, only a few phylogenetic relationships have reached acceptance because of strong gene-tree species tree discordance. Divergence times estimates in the group also vary largely between studies. These uncertainties impeded the understanding of the biogeographical history of the group, such as when and how trans-equatorial dispersal and subsequent speciation events occurred. Here, we used high-coverage genome-wide sequencing for 14 of the 15 species of Otariidae to elucidate the phylogeny of the family and its bearing on the taxonomy and biogeographical history. Despite extreme topological discordance among gene trees, we found a fully supported species tree that agrees with the few well-accepted relationships and establishes monophyly of the genus Arctocephalus. Our data support a relatively recent trans-hemispheric dispersal at the base of a southern clade, which rapidly diversified into six major lineages between 3 and 2.5 Ma. Otaria diverged first, followed by Phocarctos and then four major lineages within Arctocephalus. However, we found Zalophus to be nonmonophyletic, with California (Zalophus californianus) and Steller sea lions (Eumetopias jubatus) grouping closer than the Galapagos sea lion (Zalophus wollebaeki) with evidence for introgression between the two genera. Overall, the high degree of genealogical discordance was best explained by incomplete lineage sorting resulting from quasi-simultaneous speciation within the southern clade with introgresssion playing a subordinate role in explaining the incongruence among and within prior phylogenetic studies of the family. [Hybridization; ILS; phylogenomics; Pleistocene; Pliocene; monophyly.].

Dental caries in wild primates: Interproximal cavities on anterior teeth.

Dental caries has been reported in a variety of primates, although it is still considered rare in wild populations. In this study, 11 catarrhine primate taxa (n = 339 individuals; 7946 teeth) were studied for the presence of caries. A differential diagnosis of lesions in interproximal regions of anterior teeth was undertaken, since they had been previously described as both carious and non-carious in origin. Each permanent tooth was examined macroscopically, with severity and position of lesions recorded. Two specimens were examined further, using micro-CT scans to assess demineralization. Differential diagnosis confirmed the cariogenic nature of interproximal cavities on anterior teeth (ICATs). Overall results show 3.3% of all teeth (i.e., anterior and posterior teeth combined) were carious (n = 262), with prevalence varying among species from 0% to >7% of teeth affected. Those with the highest prevalence of ICATs include Pan troglodytes verus (9.8% of anterior teeth), Gorilla gorilla gorilla (2.6%), Cercopithecus denti (22.4%), Presbytis femoralis (19.5%), and Cercopithecus mitis (18.3%). ICATs make up 87.9% of carious lesions on anterior teeth. These results likely reflect dietary and food processing differences among species, but also between the sexes (e.g., 9.3% of all female P. troglodytes verus teeth were carious vs. 1.8% in males). Processing cariogenic fruits and seeds with the anterior dentition (e.g., wadging) likely contributes to ICAT formation. Further research is needed in living primate populations to ascertain behavioral/dietary influences on caries occurrence. Given the presence of ICATs in frugivorous primates, their diagnosis in archaeological and paleontological specimens may shed light on diet and food processing behaviors in fossil primates.

Tooth chipping prevalence and patterns in extant primates.

OBJECTIVES: A tooth chip occurs when a hard object forcefully contacts the surface of the tooth, typically removing enamel from the occlusal edge. In this study, chipping patterns in extant primates were compared, and hard-object-feeding assessed alongside other factors (e.g., grit mastication and dental properties), to elucidate dietary and behavioral inferences in archeological and paleontological samples. MATERIALS AND METHODS: Thirteen species of extant primates were studied, including eight species within the Cercopithecidae, two within the Ceboidea, and three within the Hominoidea. Four additional species were also incorporated from the literature for some of the analyses. The severity (Grade 1-3), position (buccal, lingual, mesial, and distal) and number of tooth fractures were recorded for each specimen. RESULTS: Species considered hard-object-feeding specialists presented higher rates of chipping, with sakis, mandrills, sooty mangabeys and Raffles' banded langurs having high chipping rates (28.3%, 36.7%, 48.4%, and 34.7% of teeth, respectively). Species that seasonally eat harder foods had intermediate chipping frequencies (e.g., brown woolly monkeys: 18.5%), and those that less commonly consume hard food items had the lowest chipping frequencies (e.g., Kloss gibbon: 7.3%; chimpanzees: 4.4%). DISCUSSION: The results suggest hard food mastication influences differences in chipping prevalence among the species studied. Although Homo fossil samples show high rates of chipping comparable to hard-object-feeding extant primates, they display a different pattern of chipping, supporting the hypothesis that these fractures are mostly non-food related (e.g., grit mastication in Homo naledi; non-masticatory tooth use in Neanderthals).

An image analysis protocol for the quantification of interglobular dentine in anthropological tooth sections.

The histological identification of interglobular dentine (IGD) in archeological human remains with macroscopic evidence of rickets has opened a promising new avenue for the investigation of metabolic disease in the past. Recent paleopathological studies have shown that histological analysis of archeological human teeth may allow the identification of periods of vitamin D deficiency occurring within very narrow developmental windows, yielding new information on the seasonality or even maternal-fetal transmission of this disease. However, currently available techniques for recording IGD rely on subjective scoring systems or visual estimations, potentially leaving them open to inter and intra-observer error and rendering comparisons of datasets difficult. Here we describe a new imaging protocol that utilizes open access software and may yield more objective and quantitative data on the amount of IGD present within a dentinal region of interest. We demonstrate that grayscale histograms in FIJI®/ImageJ® might be used to provide less subjective estimates of the percentage of a region of interest affected by IGD. Application of this technique may enable more accurate comparison of datasets between researchers.

An inconstant biorhythm: The changing pace of Retzius periodicity in human permanent teeth.

OBJECTIVES: Human tooth enamel retains evidence of growth in the form of Retzius lines. The number of daily growth increments between the regularly occurring lines defines their repeat interval, or periodicity. Retzius periodicity is often incorporated into enamel formation times, age-at-death reconstructions, or used to provide a basis from which to explore an underlying biorhythm. Biological anthropologists typically assume that RP remains constant within an individual and does not vary along the tooth-row. Here, we test that assumption. MATERIALS AND METHODS: RP was calculated from n = 223 thin sections of human permanent teeth from individuals of British and southern African origin. Forty individuals provided multiple teeth (n = 102 teeth) and a further 121 individuals each provided a single tooth. RESULTS: We report first evidence that RP of permanent teeth does not always remain constant within an individual. Of those individuals that provided multiple teeth, 42% (n = 17/40) demonstrated a decrease in RP along the tooth row, with most shifting by two or more days (n = 11). Across the entire sample, mean RP of anterior teeth was significantly higher than molars. Mean premolar RP tended to be intermediate between anterior teeth and molars. DISCUSSION: Our data do not support the assumption that RP invariably remains constant within the permanent teeth of an individual. Transferring RP from molars to incisors within an individual can result in a miscalculation of formation time and age-at-death by up to 1 year. Implications for biological anthropologists and the source of the underlying long period biorhythm are discussed.

Ultrastructure and properties of primary carious molars treated using the Hall Technique.

BACKGROUND: The Hall Technique (HT) is a method of restoring decayed primary teeth using stainless steel crowns (SSCs) without tooth preparation, caries removal, or local anaesthetic. AIM: To investigate the ultrastructural, biomechanical, and chemical characteristics of teeth managed with the Hall Technique in comparison with conventional SSC (controls). DESIGN: Twelve HT-treated primary molars and four controls were analysed. Teeth were dehydrated in ethanol, embedded in methylmethacrylate, mesio-distally sectioned, X-rayed, mounted, and polished. Biomechanical, ultrastructural, and chemical characterisation was performed for carious lesion and sound areas of each specimen. RESULTS: Pre-treatment and post-treatment X-rays showed evidence of little to no caries progression over time. In carious lesions, mean hardness and elastic modulus values were lower in HT-treated teeth than in controls. In both controls and HT-treated teeth, carious lesions had the lowest %wt of Ca and P of all tissues sampled. CONCLUSIONS: Although the retained carious tissue was biomechanically more compromised in HT-treated teeth, the Ca and P values were higher than reported elsewhere for carious lesions in primary molars, suggesting remineralisation may have occurred in caries in HT-treated teeth. Future investigations will help elucidate the processes involved with carious lesion arrest under SSC.

Dentistry students' experiences, engagement and perception of biochemistry within the dental curriculum and beyond.

INTRODUCTION/OBJECTIVES: Basic knowledge at the molecular level is necessary to care for the orofacial complex as part of the whole body. Many undergraduate dentistry students struggle to engage with biochemistry during the degree due to difficulty in appreciating the relevance of biochemistry to clinical practice. This study investigated student experiences, perception and engagement with biochemistry as part of the dental curriculum and explored how the teaching of biochemistry might be further developed. METHODS: Focus groups were conducted with 21 participants, in groups of four to six students from the 3rd year to 5th year, as well as with recent graduates and post-graduate students from a prominent Australasian dental school. Data were analysed using a general inductive approach. RESULTS: Focus group participants viewed the oral biochemistry module as well organised and professionally run. However, participants reported that the large amount of material taught in the module made them feel overwhelmed and demotivated. Biochemistry was regarded by undergraduate participants as relevant to dental practice, but graduate participants thought it was only relevant to those sitting examinations for further training. Biochemistry was perceived as most relevant to dental research and expanding scientific literacy. DISCUSSION/CONCLUSIONS: Participants in this study suggested that reducing the amount of material taught, focusing on dentally relevant biochemical concepts and overtly stating the connection of biochemistry to clinical practice could increase engagement and enhance the module within the dental curriculum.

Perception of health and educational risks amongst dental students and educators in the era of COVID-19.

OBJECTIVE: To investigate the perceived educational and health risks associated with the COVID-19 pandemic amongst dental students and educators. METHODS: A 17-item electronic survey was sent to 496 undergraduate dental students and 53 clinical faculty members who attended clinical sessions during the outbreak period. The survey explored various aspects related to primary sources and prevention of disease exposure, dental management of suspected cases, impact of COVID-19 on students' clinical performance and effects of suspension of educational activities on academic performance and clinical competence. RESULTS: The response rate of the students' was 60.7% (n = 301). The majority of students reported that performing clinical work during the outbreak posed significant health concerns, resulted in a significant stress and negatively affected their clinical performance. The majority of students believed that aerosols generated during dental procedures are the major source for disease exposure and universal protective equipment is not effective for prevention. The decision to suspend teaching activities was supported by 89% of the students. Opinions were divided regarding the impact of the suspension on the academic performance and clinical competence. Educational videos were the most preferred form of distance education. The response rate of faculty members was 60.4% (n = 32). Responses of faculty members were similar to students, though fewer concerns were reported regarding the risk of disease transmission. All respondents agreed that extra-precautionary measures are required to ensure optimum protection against disease exposure. CONCLUSIONS: The recent COVID-19 outbreak has adversely affected various elements of dental education. High levels of major health risk perception were noted amongst students and educators. The interruption to academic and clinical activities may lead to an inevitable skill deficit within the new generation of dental graduates. Educators are under significant pressure to accommodate abrupt changes in teaching methods, find solutions to mitigate skill deficit and ensure safe clinical practice once clinical activities are resumed.

Knowledge of dental enamel defects amongst undergraduate dental students-a cross-sectional survey.

INTRODUCTION/OBJECTIVES: Enamel defects are disturbances in the quantity or quality of enamel, due to disruption or damage to the enamel organ during amelogenesis. The correct diagnosis of enamel defects is critical as diverse management options could be required for different conditions. Difficulties in diagnosis can happen, because these defects may have similar clinical presentations. This study evaluated the diagnostic skills in enamel defects of dental students of a prominent Australasian school. METHODS: A questionnaire consisting of clinical photographs of the affected teeth/dentition in multiple views and four standardised questions for each case of enamel defect were given to Year 4 and Year 5 students. RESULTS: Localised/Chronological Hypoplasia had the lowest percentage of correct diagnosis (20.5%), whilst Enamel White Spot Lesions (EWSLs) had the highest (85%). Localised/Chronological Hypoplasia had the lowest aetiology score (20.5%), and the highest was obtained for EWSLs (85%). In regard to which question to ask to gain insight into the conditions, Enamel Hypomineralisation/MIH had the lowest score for both Year 4 and Year 5 respondents (35.4% and 21.3%). Most respondents agreed more teaching in this topic was needed, with further clinical sessions to observe the enamel defects, workshops/seminars, lectures and student-driven presentations suggested. CONCLUSION: Final-year dental students showed variable knowledge in diagnosis, aetiology and clinical management of enamel defects. Further didactic and clinical teaching should be incorporated in the undergraduate curriculum on this topic .

Graduate mobility: Where do dentistry graduates choose to practise?

BACKGROUND AND OBJECTIVE: The international higher education market has grown and developed rapidly. International students generate attractive income for host universities, and gaining an international education benefits students in an increasingly globalised world. However, there is little research regarding where international students intend to work and settle beyond graduation. This study investigated where dentistry students intended to practise after graduation, and whether international students who graduated between 2001 and 2016 are currently practising in their host country (New Zealand) or have migrated overseas. METHODS: A cross-sectional survey was used to investigate current students' intended destination of practice after graduation. Additionally, names of international graduates since 2001 were matched against the 2017 register of practitioners to determine if they were currently registered to practise in their host country. A frequency and bivariate analysis was conducted. RESULTS: Almost 64% of current international students indicated their intention to stay in their host country after graduation. However, only 22% of graduates since 2001 were currently practising in New Zealand. The number of international graduates who registered to practise in New Zealand increased between 2001 and 2016. CONCLUSION: Less than one-quarter of international graduates were currently practising in their host country; however, longitudinal data showed that this is an increasing trend. These findings can be used to inform how we might prepare current and future graduates for both local and globalised labour markets.

Radiographic Assessment of Dental Pathology and Abnormalities in Dolphins.

This study proposes a simple standardized method for the production of analog X-ray images of dolphin teeth, and to explore its potential use as a complementary technique in the evaluation of dental pathology in small cetaceans. We investigated exposure times that produced the best results, and whether radiographs helped in the diagnosis of macroscopic abnormalities. Teeth of six species of dolphins (Delphinidae: Tursiops truncatus, Steno bredanensis, Sotalia guianensis, Delphinus sp., Stenella coeruleoalba, and Stenella frontalis) were X-rayed in an analog dental X-ray machine operating at 70 kVp and 7 mA. Intraoral size 2 standard films were used, and the focus-film distance was standardised at 35 cm. Those species with smaller teeth (total length 12-20 mm) had the best results when exposed for 0.3 seconds, while species with larger teeth (30-45 mm) had to be exposed for 0.4 seconds for their best result. Three independent examiners analysed all the images taken. The average pairwise percent agreement was 73% (Fleiss' Kappa = 0.229), suggesting fair agreement between examiners. Analog X-ray images produced were useful in complementing the diagnosis of dental pathology and abnormalities in dolphins, in addition to allowing the observation of internal details and lesion depths, which would not be possible with conventional macroscopic methods. The use of analog X-ray imaging is easily applicable to the study of dolphin teeth, with low operating costs and simple logistics compared to other non-destructive analytical approaches such as Micro-CT.

Enamel ultrastructure of fossil and modern pinnipeds: evaluating hypotheses of feeding adaptations in the extinct walrus Pelagiarctos.

This study aimed to assess the enamel ultrastructure in modern otariid pinnipeds and in the extinct walrus Pelagiarctos. Teeth of the New Zealand fur seal (Arctocephalus forsteri), sea lion (Phocarctos hookeri), and fossil walrus Pelagiarctos thomasi were embedded, sectioned, etched, and analyzed via scanning electron microscopy. The enamel of NZ otariids and Pelagiarctos was prismatic and moderately thick, measuring 150-450 µm on average. It consisted of transversely oriented Hunter-Schreger bands (HSBs) from the enamel-dentine junction (EDJ) to near the outer surface, where it faded into prismless enamel less than 10 µm thick. The width of HSB was variable and averaged between 6 and 10 prisms, and they presented an undulating course both in longitudinal and cross sections. The overall organization of the enamel was similar in all teeth sampled; however, the enamel was thicker in canines and postcanines than in incisors. The crowns of all teeth sampled were uniformly covered by enamel; however, the grooved incisors lacked an enamel cover on the posterior side of the buccal face. Large tubules and tuft-like structures were seen at the EDJ. HSB enamel as well as tubules and tufts at the EDJ suggest increased occlusal loads during feeding, a biomechanical adaptation to avoid enamel cracking and failure. Despite overall simplification in tooth morphology and reduced mastication, the fossil and modern pinnipeds analyzed here retained the complex undulating HSB structure of other fossils and living Carnivora, while other marine mammals such as cetaceans developed simplified radial enamel.

The effect of hydrothermal spark discharge anodization in the early integration of implants in sheep sinuses.

OBJECTIVES: Spark discharge anodic oxidation forms a porous oxide film on titanium implant surfaces, which may increase surface roughness and enhance early osseointegration. This study aimed to clinically and histomorphometric compare commercially-available sandblasted (RBM) implants, treated with hydrothermal anodization and placed into an animal maxillary sinus model. MATERIALS AND METHODS: Thirty 3.75 mm × 8.5 mm threaded titanium implants were placed into the maxillary sinuses of 10 sheep via an external approach, with three test groups and 10 implants per group: right side, Control = CP-titanium with RBM surface, Test group 1 = CP-titanium with RBM + anodized surface; left side, Test group 2 = Ti-6Al-7Nb with RBM + anodized surface. Schneiderian membranes were elevated but not bone grafted. Resonant frequency analysis (RFA) was measured at surgery. Animals were sacrificed after 1 month unloaded healing. Resin-embedded undemineralized ground-sections were digitised, and mean bone-implant contact (% BIC) was measured bilaterally for the best-three consecutive threads. RESULTS: Seven of 30 implants showed signs of failure. RFA was low at placement but did not differ between the groups (group mean ISQ values ranged from 23 to 35; χ(2)  = 0.37). RFA was not repeated at sacrifice due to implant instability. Histomorphometric analysis showed % BIC was highest for control (34.8 ± 15.7), followed by Test 1 (29.6 ± 18.1) and Test 2 implants (23.3 ± 22.7), but this difference was not statistically significant (χ(2)  = 0.3). DISCUSSION AND CONCLUSIONS: Early integration of RBM implants placed into thin maxillary sinus walls was not enhanced by hydrothermal anodization of implant surfaces. This may be related to the initial low stability of the implants and the relatively short healing period. However, non-anodized RBM surfaces showed promising results, with % BIC values comparable to the best estimates of other studies using sinus grafting. Whether the modification of the implant surfaces through anodization with simultaneous sinus grafting would promote enhanced early osseointegration, is a subject of future research.

Elemental and chemical characterization of dolphin enamel and dentine using X-ray and Raman microanalyzes (Cetacea: Delphinoidea and Inioidea).

Dolphins show increased tooth number and simplified tooth shape compared to most mammals, together with a simpler ultrastructural organization and less demanding biomechanical function. However, it is unknown if these factors are also reflected in the chemical composition of their teeth. Here, the bulk chemical composition and elemental distribution in enamel and dentine of extant dolphins were characterized and interpreted using X-ray and spectroscopy techniques. Teeth of 10 species of Delphinida were analyzed by WDX, EDX and Raman spectroscopy. For most of the species sampled, the mineral content was higher in enamel than in dentine, increasing from inner towards outer enamel. The transition from dentine to enamel was marked by an increase in concentration of the major components Ca and P, but also in Na and Cl. Mg decreased from dentine to enamel. Concentrations of Sr and F were often low and below detection limits, but F peaked at the outer enamel region for some species. Raman spectroscopy analyzes showed characteristics similar to carbonated hydroxyapatite, with the strongest peak for the phosphate PO4(3-) stretching mode at 960-961cm(-1). Dentine samples revealed a higher diversity of peaks representative of organic components and proteins than enamel. The similar distribution pattern and small variation in average concentration of major and minor elements in dentine and enamel of dolphins suggest that they are subject to strong physiological control. A clear trend of the elemental variations for all dolphin species sampled suggests that the general pattern of tooth chemistry is conserved among the Mammalia.