Internal Tooth Structure Research Articles

Radular Tooth Coating in Members of Dendronotidae and Flabellinidae (Nudibranchia, Gastropoda, Mollusca).

Nudibranchs, with their mesmerizing diversity and ecological significance, play crucial roles in marine ecosystems. Central to their feeding prowess is the radula, a chitinous structure with diverse morphologies adapted to prey preferences and feeding strategies. This study focuses on elucidating wear coping mechanisms in radular teeth of carnivorous molluscs, employing Dendronotus lacteus (Dendronotidae) and Flabellina affinis (Flabellinidae) as model species. Both species forage on hydrozoans. Through scanning electron microscopy, confocal laser scanning microscopy, nanoindentation, and energy-dispersive X-ray spectroscopy, the biomechanical and compositional properties of their teeth were analyzed. Notably, tooth coatings, composed of calcium (Ca) or silicon (Si) and high hardness and stiffness compared to the internal tooth structure, with varying mineral contents across tooth regions and ontogenetic zones, were found. The presence of the hard and stiff tooth coatings highlight their role in enhancing wear resistance. The heterogeneities in the autofluorescence patterns related to the distribution of Ca and Si of the coatings. Overall, this study provides into the biomechanical adaptations of nudibranch radular teeth, shedding light on the intricate interplay between tooth structure, elemental composition, and ecological function in marine molluscs.

Relationship between external and internal structures in deciduous teeth: a multidisciplinary study.

The different dental structures of deciduous teeth have always been regarded with great interest in endodontics and restorative dentistry. Nevertheless, there are still few investigations on the morphology of deciduous teeth compared to the permanent ones, due to the difficulty in obtaining sound deciduous teeth suitable for measurement. The aim of this research is to evaluate and compare the internal and external structures of deciduous teeth from completely preserved hominid findings, using X-ray and micro-CT examination. Samples were photographed using a digital camera and were then analysed by X-ray and micro-CT. Different parameters of external and internal structures were calculated to obtain a normalisation coefficient, called the P-factor. There is a constant correlation between external and internal structure, regardless of gender, type, shape or arch sector.

Further analyses of the structural organization of Homo luzonensis teeth: Evolutionary implications

The species Homo luzonensis has recently been described based on a set of dental and postcranial elements found at Callao Cave (Northern Luzon, Philippines) and dated to at least 50–67 ka. Seven postcanine maxillary teeth are attributed to this taxon, five of them belonging to the same individual (CCH6) and representing the holotype of H. luzonensis, whereas the isolated upper premolar CCH8 and the upper third molar CCH9 are paratypes of the species. The teeth are characterized by their small dimensions associated with primitive features, as also found in Homo floresiensis, another hominin having evolved in an insular environment of Southeast Asia. Postcranial bones of the hands and feet of H. luzonensis and H. floresiensis show Homo habilis–like or australopith-like features, whereas cranial and dental morphology are more consistent with the Asian Homo erectus morphology. Due to this mosaic morphology, the origin and phylogenetic relationships of both H. luzonensis and H. floresiensis are still debated. To test the hypotheses that H. luzonensis derives from H. erectus or from an earlier small-brained hominin, we analyzed the µCT scans of the teeth. We investigated both external and internal tooth structure using morphometric methods including: crown outline shape, tooth crown tissue proportions, enamel-dentine junction shape, and pulp morphology. Homo luzonensis external crown morphology aligns more with H. erectus than with H. habilis/H. rudolfensis. The internal structural organization of H. luzonensis teeth exhibits more affinities with that of H. erectus and H. floresiensis than with Neanderthals and modern humans. Our results suggest that both H. floresiensis and H. luzonensis likely evolved from some H. erectus groups that dispersed in the various islands of this region and became isolated until endemic speciation events occurred at least twice during the Pleistocene in insular environments.

Effect of application of turmeric extract powder solution on the color changes of non-vital teeth: An in-vitro study

Aim: The aim of this study was to assess the effect of using turmeric powder extract on changes of tooth color with extra-coronal and intra-coronal bleaching methods. Materials and Methods: Turmeric powder extract was weighted and mixed with two different hydrogen peroxide concentrations (3% and 6%) to be used as a bleaching agent. Thirty teeth were allocated into three groups (n = 10): Group A: bleaching agent (6%) was applied on the labial surface, Group B: bleaching agent (3%) was applied inside the pulp chamber, and Group C: extra- and intra-coronal bleaching techniques were used (6% and 3%, respectively). A standardized access cavity was opened in the palatal surface of each tooth in both Groups B and C. Color parameters were measured using a spectrophotometer. Results: A statistically significant difference in color difference values (∆E*) and enamel brightness (∆L*) was found between Group C and each of Groups A and B. There was no statistically significant difference in (∆E*) and (∆L*) between Group A and Group B. The highest mean value of (∆E*) and (∆L*) was found in Group C, whereas the least mean value was found in Group B. Conclusion: Bleaching the external and internal tooth structure with low concentrations of hydrogen peroxide solution mixed with turmeric extract has a promising effect in color enhancement.

Ultramicrostructural reductions in teeth: implications for dietary transition from non-avian dinosaurs to birds

BackgroundTooth morphology within theropod dinosaurs has been extensively investigated and shows high disparity throughout the Cretaceous. Changes or diversification in feeding ecology, i.e., adoption of an herbivorous diet (e.g., granivorous), is proposed as a major driver of tooth evolution in Paraves (e.g., Microraptor, troodontids and avialans). Here, we studied the microscopic features of paravian non-avian theropod and avialan teeth using high-spatial-resolution synchrotron transmission X-ray microscopy and scanning electron microscopy.ResultsWe show that avialan teeth are characterized by the presence of simple enamel structures and a lack of porous mantle dentin between the enamel and orthodentin. Reduced internal structures of teeth took place independently in Early Cretaceous birds and a Microraptor specimen, implying that shifts in diet in avialans from that of closely related dinosaurs may correlate with a shift in feeding ecology during the transition from non-avian dinosaurs to birds.ConclusionDifferent lines of evidence all suggest a large reduction in biting force affecting the evolution of teeth in the dinosaur-bird transition. Changes in teeth microstructure and associated dietary shift may have contributed to the early evolutionary success of stemward birds in the shadow of other non-avian theropods.

New Findings on Internal Tooth Structure Obtained by the OCT Analysis

New Findings on Internal Tooth Structure Obtained by the OCT Analysis

Enamel thickness and dental development in Rudapithecus hungaricus

The fossil record of middle and late Miocene Eurasian hominoids has expanded considerably over the past few decades, particularly with the recovery of numerous isolated teeth and jaws. Scholars have turned to assessments of internal tooth structure and growth to make sense of the evolutionary radiations of these primates as well as their affinities to the living great apes (hominids). Here we characterize full-dentition enamel thickness and dental development in several juvenile Rudapithecus hungaricus individuals using multiple imaging modalities. Relative enamel thickness (RET) values for the anterior teeth and premolars of Rudapithecus are broadly akin to those of gorillas and chimpanzees and are thinner than those of orangutans. First molar RET values are most similar to chimpanzees, while posterior molar values are closer to thicker-enameled orangutans. When compared to Miocene hominoids, Rudapithecus shows an intermediate molar RET condition that is especially similar to other dryopithecines. Long-period line periodicity values are comparable to African apes and most Miocene hominoids, and lower than living and fossil orangutans. The mean cuspal daily secretion rate is similar to that of several other Miocene hominoids but is greater than extant great apes. Cusp-specific molar crown formation times generally exceed those of chimpanzees, are lower than those of orangutans, and are broadly like those of other Miocene apes. While Rudapithecus appears to have a somewhat unique pattern of enamel thickness and dental development relative to individual great ape genera, these structural and developmental features are consistent with its designation as a hominid.

Dentinal Adaptation of Warm Thermoplastic Obturating Material and Cold Thermoplastic Obturating Material: An In vitro Study.

Introduction:The objective of endodontic obturation is to provide a complete seal along the length of the root canal system, thereby ensuring the healing and sustained health of the periradicular tissue. Root canal obturation involves the three-dimensional filling of the entire root canal system and is a critical step in endodontic therapy. Gutta-percha has universally been accepted as the gold standard for root canal filling materials. However, it lacks bonding to the internal tooth structure resulting in the absence of complete seal.Aim:The aim of the present study is to compare the dentinal adaptation of warm thermoplastic obturating material and cold thermoplastic obturating materials.Materials and Methods:Thirty single-rooted, anterior noncarious human teeth extracted for periodontal or orthodontic reasons were used for the study. The samples were stored in distilled water until obturation. The specimens were then randomly divided into three groups of ten specimens each: Control group – Cold lateral condensation with AH Plus, Group I – Endosure with AH Plus®, and Group II – GuttaFlow® 2 with master cone. The obturation for each group was done following manufacturer's instructions. Under On-demand software, the area of voids at the level of 3 mm, 5 mm, and 8 mm from the apex was observed for all the samples. The obtained results were submitted for statistical analysis.Results:The result in the present study showed that Endosure provides a better consistent seal as compared to cold lateral condensation, or GuttaFlow 2 techniques.Conclusion:Mean void value was maximum for GuttaFlow 2 group, followed by cold lateral condensation, Endosure. Though there was a difference in the mean void values, it was not statistically significant except between Endosure and GuttaFlow 2. The result in the present study showed that Endosure provides a better seal as compared to cold lateral compaction, GuttaFlow 2 or Endosure technique.

3D models related to the publication: Internal tooth structure and burial practices: insights into the Neolithic necropolis of Gurgy (France, 5100-4000 cal. BC).

The present 3D Dataset contains the 3D models of external and internal aspects of human upper permanent second molars from the Neolithic necropolis analyzed in the following publication: Le Luyer M., Coquerelle M., Rottier S., Bayle P.: Internal tooth structure and burial practices: insights into the Neolithic necropolis of Gurgy (France, 5100-4000 cal. BC).

Internal Tooth Structure and Burial Practices: Insights into the Neolithic Necropolis of Gurgy (France, 5100-4000 cal. BC).

Variations in the dental crown form are widely studied to interpret evolutionary changes in primates as well as to assess affinities among human archeological populations. Compared to external metrics of dental crown size and shape, variables including the internal structures such as enamel thickness, tissue proportions, and the three-dimensional shape of enamel-dentin junction (EDJ), have been described as powerful measurements to study taxonomy, phylogenetic relationships, dietary, and/or developmental patterns. In addition to providing good estimate of phenotypic distances within/across archeological samples, these internal tooth variables may help to understand phylogenetic, functional, and developmental underlying causes of variation. In this study, a high resolution microtomographic-based record of upper permanent second molars from 20 Neolithic individuals of the necropolis of Gurgy (France) was applied to evaluate the intrasite phenotypic variation in crown tissue proportions, thickness and distribution of enamel, and EDJ shape. The study aims to compare interindividual dental variations with burial practices and chronocultural parameters, and suggest underlying causes of these dental variations. From the non-invasive characterization of internal tooth structure, differences have been found between individuals buried in pits with alcove and those buried in pits with container and pits with wattling. Additionally, individuals from early and recent phases of the necropolis have been distinguished from those of the principal phase from their crown tissue proportions and EDJ shape. The results suggest that the internal tooth structure may be a reliable proxy to track groups sharing similar chronocultural and burial practices. In particular, from the EDJ shape analysis, individuals buried in an alcove shared a reduction of the distolingual dentin horn tip (corresponding to the hypocone). Environmental, developmental and/or functional underlying causes might be suggested for the origin of phenotypic differences shared by these individuals buried in alcoves.

Management of self-inflicted dental injuries with various nonsurgical techniques: Case series

Children have a common habit of exploring carious or traumatically exposed teeth using various foreign objects such as metal screws, staple pins, darning needles, pencil leads, beads, paper clip, and toothpicks, which may sometimes break inside the pulp chamber or root canal. Majority of such cases are asymptomatic and hence diagnosed accidentally on routine radiographic examination. However, embedded foreign objects may sometimes act as a potential source of infection and are convoyed with pain or recurrent swelling. Dentists must be aware of the self-inflicted dental injury, its consequences, and selection of the all-inclusive treatment strategies giving due consideration to cost-benefit ratio of the different treatment options. This case series highlights the possible dental consequences of placing foreign objects in the mouth and various management strategies. Four cases of self-inflicted dental injuries involving patients aged 10–20 years are presented and investigated from the endodontic, pedodontic, and psychiatric viewpoints. In all cases, the cause has been easily identified by clinical appearance corroborated with a good history. This paper discusses a nonsurgical technique to retrieve these objects from the root canal with minimal damage to internal tooth structure.

Talonid crests expression at the enamel–dentine junction of hominin lower permanent and deciduous molars

The application of microtomography (mCT) to dental morphological studies has unveiled a new source of palaeobiological information, particularly in the analysis of the internal structures of teeth. In this study, we assess the expression of talonid crests at the enamel and dentine surfaces in lower permanent and second deciduous molars (M2 and dm2) of H. sapiens, H. neanderthalensis and Atapuerca-Sima de los Huesos (SH) hominins. In modern humans, talonid crests are described exclusively in the deciduous teeth (Korenhof, 1982) and interpreted as a primitive mammalian remnant of the talonid attachment to the trigonid. Here we report for the first time the expression of talonid crests of deciduous and permanent molars in H. sapiens, H. neanderthalensis and Middle Pleistocene hominins. We discuss possible evolutionary interpretations and suggest the importance of recording this feature in future studies.

Validation of swept source optical coherence tomography (SS-OCT) for the diagnosis of smooth surface caries in vitro

ObjectiveAn accurate evaluation of the extent of dental caries and possible progress of the lesion from enamel into dentin is very important in clinical dentistry. Dentists need an imaging technology that can noninvasively and reliably quantify the extent of caries. This study aimed to evaluate the effectiveness of non-polarized swept source optical coherence tomography (OCT) in evaluating the extent of caries on smooth enamel surfaces. MethodsOne-hundred and twenty-seven investigation sites on the enamel surfaces of 93 extracted teeth were selected randomly and examined visually. The presence and extent of caries were scored by experienced and inexperienced dentists using each observation method (0: no caries; 1: enamel demineralization without surface breakdown; 2: enamel breakdown due to caries; 3: deep caries involving the dentin). The same locations were then examined using OCT, following which the teeth were sectioned using a diamond saw and viewed directly under a confocal laser scanning microscope (CLSM). Sensitivity and specificity indices for OCT and VI were calculated and compared. The results were analysed statistically using receiver operating characteristic (ROC) curves. ResultsEnamel and dentin caries were outlined by a visible boundary on the cross-sectional OCT images. The modality showed superior results for the detection of dentinal caries; higher sensitivity and Az values could be obtained in the ROC curves, especially by experienced dentists. ConclusionsCross-sectional imaging of the natural caries lesions on smooth enamel surface by OCT enables efficient diagnosis of the lesion type, extent and dentin involvement. Clinical significanceSS-OCT can demonstrate the cross-sectional image of smooth surface enamel caries as highlighted zone in tomogram. It is crucial to determine the extent of the lesion, whether it reaches beyond DEJ or not by a non-invasive and safe technique. OCT can give clinicians information about internal tooth structure and will help clinical decision making on surgical intervention.

Quantitative evaluation of the accuracy of micro‐computed tomography in tooth measurement

Micro-computed tomography (MCT) is a noninvasive technique for visualizing morphological characteristics of teeth in a detailed and accurate manner, without causing any tooth destruction. A large amount of information can be obtained from such scans. The slices can be recreated in any plane, and the data can be represented as either two-dimensional (2D) or three-dimensional (3D) images. In addition, the internal and external anatomy can be demonstrated simultaneously or separately, and the images can be assessed qualitatively and quantitatively. However, only the qualitative accuracy of MCT had been evaluated previously. The aim of the present study was to evaluate the accuracy of MCT quantitatively by comparing the values obtained by MCT with those of other imaging methods. Twelve teeth were scanned using a desktop X-ray micro-CT scanner, and the images were reconstructed and measured. Values obtained by direct measurement served as the primary reference for linear measurements. Measurements made by a 3D scanner and by photography were additional references. MCT was found to be a reliable method of making linear measurements and may be a useful device for measuring distance and for observing both internal and external tooth structure using the reconstructed 3D form.

Survival Rate and Fracture Strength of Incisors Restored with Different Post and Core Systems and Endodontically Treated Incisors without Coronoradicular Reinforcement

This in vitro study evaluated the survival rate and fracture resistance of maxillary central incisors restored with different post and core systems. The post and core systems investigated were a prefabricated high precious metal post with cast core (group A), zirconia post with a prefabricated bonded ceramic core (group B), and a resin-ceramic interpenetrating phase composite post (experimental) with a prefabricated bonded ceramic core (group C). The all-ceramic copings were cemented using Panavia 21 TC. In the group without coronoradicular reinforcement, the access cavity was closed with a light-cured composite in combination with a dentine-bonding agent (group D). Each specimen was intermittently loaded and thermocycled before final stress tests in a Zwick machine. The survival rates after 1,200,000 cycles in the artificial mouth were 90% (group A), 80% (group B), 60% (group C), and 100% (group D). Statistically significant differences were found between all groups with the exception of A and B, when failure during cyclic loading was included (Kruskal-Wallis multiple comparisons test). Samples restored with a cast post and core demonstrated more vertical root fractures. It was concluded that the preservation of both internal and external tooth structure is of utmost importance when restoring endodontically treated teeth.

レーザーを用いたコヒーレント検出画像計測法による歯のコンピュータ断層（ＣＴ）画像の分光的測定

Optical computed tomography of human teeth is demonstrated by the coherent detection imaging method. The optical heterodyne detection technique with three different-wavelength lasers as the sources is used to obtain the optical tomographic images of extracted human teeth in the visible short wavelength to near IR regions. The different layers of the internal structure of tooth can be clearly reconstructed with high resolution. The image contrast is shown to be wavelength dependent and compared between the same extracted sample with and without saline in the pulp cavity.

In vivo confocal microscopy in clinical dental research: An initial appraisal

Until recently, the in vivo microscopic investigation of intraoral tissues at high resolution has been virtually impossible. Confocal microscopy enables high-resolution imaging to be achieved below semitransparent surfaces in intact living specimens, but this may still be impractical for intraoral applications because of the need to stabilize the sample. The development of a steadying objective (x 240 overall mag.) which is held against the sample surface and is focused by moving internal elements, avoids the need for fine adjustment of the living sample under the microscope to achieve a change of focus. It is therefore more comfortable and also reduces the problems of movement due to the pulse. The objective was used with a tandem scanning microscope, with images recorded via a SIT video camera. Using this system internal tooth structure (e.g. enamel prisms/adhesive restoration interfaces) and the lining cells of the gingival crevice through to the junctional epithelium may be examined. It is also possible to image the oral mucous membrane, focusing to the capillary loops in the basal layers, where streaming red blood cells can be seen. Access is limited to the anterior regions as far back as the premolar teeth. Applications could include caries research, soft and hard tissue responses to biomaterials (e.g. implants), wound healing and monitoring the effect of periodontal treatment regimens. This new technique offers numerous exciting opportunities for the microscopic investigation of many clinical operative procedures in vivo, allowing the response of the tissues to be non-destructively monitored, over time, at high resolution.

An evaluation of post length within the elastic limits of dentin

Posted teeth were evaluated to determine the reinforcement capabilities of various post lengths. The results suggest that as internal tooth structure is removed from the tooth the tooth becomes weaker, that teeth with posts do show more reinforcement than nonposted teeth with the same manipulation characteristics, and that some load transfer appears to exist with cemented posts.

Tooth fracture\\3-A comparison of endodontic and restorative treatments

Little attention has been given to the resistance to fracture of teeth that have been endodontically treated and subsequently restored. This study investigates the impact resistance of maxillary central incisors to simulated trauma. Untreated teeth, teeth treated endodontically, and teeth restored with the use of parallel stainless steel posts were subjected to identical impacts. The absorbed energy values recorded for each group were compared with changes in the size of the endodontic preparation and the post diameter. Results of the study show that preservation of internal tooth structure and the use of smaller posts in teeth that have been endodontically treated provide maximum resistance to fracture.

Observation of internal structures of teeth by ultrasonography.

Preliminary experiments with high-resolution intensity-modulated ultrasonography techniques developed for ophthalmological diagnosis have demonstrated that at a frequency of 15 megacycles per second some internal structures can be seen in vital teeth. A relationship between time, tooth vitality, and ultrasonic viewing was observed.