Glycation promotes pulp calcification in Type 2 diabetes rat model

OBJECTIVES

Intrapulpal calcifications can occur in the dental pulp of patients with diabetes. We focused on the association between ectopic calcifications in the dental pulp and advanced glycation end products (AGEs) in Spontaneously Diabetic Torii (SDT)-fatty rats, an obese type 2 diabetic rat model, to determine the mechanism of calcification with pulp stone in the dental pulp.

MATERIALS AND METHODS

Pathologic calcification in the dental pulp of SDT-fatty rats was observed using electron microscopy and immunohistochemical analysis. Moreover, mechanical analysis of periapical region of molar tooth against occlusal force was performed.

RESULTS

In SDT-fatty rats, pathogenic pulpal calcifications occurred during blood glucose elevation after 6 weeks, and granular calcification was observed in the dental pulp after 11 weeks. Pentosidine, a major AGE, and the receptor for AGEs were strongly expressed in the dental pulp of SDT-fatty rats. S100A8, TNF-α, and IL-6 also showed positive response in the dental pulp of the SDT-fatty rat, which indicated pulpal inflammation. Blood flow disorder and hypoxic dental pulp cells were also observed. In silico simulation, strain from occlusal force concentrates on the root apex.

CONCLUSIONS

Glycation makes blood vessels fragile, and occlusal forces damage the vessels mechanically. These are factors for intrapulpal calcification of diabetes.

A new genus of japygids (Diplura: Japygidae) in mid-Cretaceous amber from northern Myanmar

Diplura is a cryptic and edaphic group of hexapod animals characterized by the presence of filiform or pincer-like cerci located at the end of the abdomen. As one of the early diverging lineages of Hexapoda, diplurans play a crucial role in unraveling the origin of the hyperdiverse insects. The fossil record of diplurans, however, is exceptionally limited due to their delicate bodies and habitat requirements. Here we report the discovery of a new japygid, Cretojapyx huangi gen. et sp. nov., entombed in mid-Cretaceous Kachin amber (northern Myanmar). This specimen exhibits distinctive features, including the well-developed carinae on abdominal segment X and cerci, left cercus lacking a prominent tooth and denticles, and right cercus with a postmedian tooth followed by uniseriate round denticles. Our finding provides a unique opportunity to gain valuable insights into the evolutionary history of this ancient lineage and deepen our understanding of terrestrial ecosystems during the Mesozoic.

Relationships in Shark Skin: Mechanical and Morphological Properties Vary between Sexes and among Species

Shark skin is a composite of mineralized dermal denticles embedded in an internal collagen fiber network and is sexually dimorphic. Female shark skin is thicker, has greater denticle density and denticle overlap compared to male shark skin, and denticle morphology differs between sexes. The skin behaves with mechanical anisotropy, extending farther when tested along the longitudinal (anteroposterior) axis but increasing in stiffness along the hoop (dorsoventral or circumferential) axis. As a result, shark skin has been hypothesized to function as an exotendon. This study aims to quantify sex differences in the mechanical properties and morphology of shark skin. We tested skin from two immature male and two immature female sharks from three species (bonnethead shark, Sphyrna tiburo; bull shark, Carcharhinus leucas; silky shark, Carcharhinus falciformis) along two orientations (longitudinal and hoop) in uniaxial tension with an Instron E1000 at a 2 mm s-1 strain rate. We found that male shark skin was significantly tougher than female skin, although females had significantly greater skin thickness compared to males. We found skin in the hoop direction was significantly stiffer than the longitudinal direction across sexes and species, while skin in the longitudinal direction was significantly more extensible than in the hoop direction. We found that shark skin mechanical behavior was impacted by sex, species, and direction, and related to morphological features of the skin.

Morphology of pulpal mineralizations: A scoping review

OBJECTIVE

The aim of this scoping review was to summarize and discuss the morphological features and associated factors of pulpal mineralizations (PMs) as described within the literature.

DATA

The study protocol was registered on the Open Science Framework platform and is available at the following link: https://osf.io/hfqwe. This scoping review was developed according to the PRISMA-ScR guidelines.

SOURCES

A literature search of four electronic databases was performed in SCOPUS, MEDLINE (PubMed), EMBASE and Word of Science, with the last search on May 29, 2023. Study selection was completed by two reviewers independently. Data was extracted regarding study characteristics, types, and features of PM and associated factors.

STUDY SELECTION

Of 1016 studies initially identified ten which qualified were included in this scoping review. Systemic and local factors that result in pulpal insult can contribute to the development of PMs. Three forms of PM have been reported, pulp stones, diffuse mineralizations, and mineralized ectopic connective tissue, with discrete and diffuse mineralization being the two clinically relevant forms. The different forms of PMs exhibit dissimilar morphological features.

CONCLUSION

Pulpal mineralizations exist in two clinically relevant forms: diffuse and discrete mineralizations and are likely associated with a pulpal insult.

CLINICAL SIGNIFICANCE

Understanding the morphology of dental pulp mineralization is the first step to expanding the knowledge of pulp mineralization and could result in improved diagnosis of endodontic pathosis.

Nativus gen. nov., a new huntsman spider genus from South America (Araneae: Sparassidae: Heteropodinae)

In this paper, the new genus, Nativus gen. nov. is proposed to include the type species, Nativus tupana sp. nov. () from Brazil and nine new species: N. carare sp. nov. (), N. hazzii sp. nov. (), N. janai sp. nov. (), N. nocaima sp. nov. (), N. tawu sp. nov. () and N. yurupari sp. nov. () from Colombia, N. juruti sp. nov. () and N. mariua sp. nov. () from Brazil, and N. napo sp. nov. () from Peru. The genus is placed in the subfamily Heteropodinae due to the presence of intermarginal denticles on the chelicerae, a long-toothed female palpal claw, two recurved eye rows with median eyes smaller than laterals, and only one lateral spine on each side of metatarsi III, as well as a ventral branch on the RTA (vRTA) in the male palp. Within Heteropodinae, it seems to be more closely related to Guadana Rheims and Sparianthina Banks due to the presence of intermarginal denticles along the entire cheliceral groove and a dorsal tegular apophysis (DTA) in the male palp. All species are described and illustrated. An identification key and distribution maps are provided for all species of the genus.

Looking for future biological control agents: the comparative function of the deutosternal groove in mesostigmatid mites

The physics of fluid laminar flow through an idealised deutosternum assembly is used for the first time to review predatory feeding designs over 72 different-sized example species from 16 mesostigmatid families in order to inform the finding of new biological control agents. Gnathosomal data are digitised from published sources. Relevant gnathosomal macro- and micro-features are compared and contrasted in detail which may subtly impact the control of channel- or 'pipe'-based transport of prey liquids around various gnathosomal locations. Relative deutosternal groove width on the mesostigmatid subcapitulum is important but appears unrelated to the closing velocity ratio of the moveable digit. Big mites are adapted for handling large and watery prey. The repeated regular distance between deutosternal transverse ridges ('Querleisten') supports the idea of them enabling a regular fluctuating bulging or pulsing droplet-based fluid wave 'sticking' and 'slipping' along the groove. Phytoseiids are an outlier functional group with a low deutosternal pipe flow per body size designed for slot-like microchannel transport in low volume fluid threads arising from daintily nibbling nearby prey klinorhynchidly. Deutosternal groove denticles are orientated topographically in order to synergise flow and possible mixing of coxal gland-derived droplets and circumcapitular reservoir fluids across the venter of the gnathosomal base back via the hypostome to the prey being masticated by the chelicerae. As well as working with the tritosternum to mechanically clean the deutosternum, denticles may suppress fluid drag. Shallow grooves may support edge-crawling viscous flow. Lateral features may facilitate handling unusual amounts of fluid arising from opportunistic feeding on atypical prey. Various conjectures for confirmatory follow-up are highlighted. Suggestions as to how to triage non-uropodoid species as candidate plant pest control agents are included.

The investigation of WNT6 and WNT10A single nucleotide polymorphisms as potential biomarkers for dental pulp calcification in orthodontic patients

The aim of this study is to evaluate if single nucleotide polymorphisms (SNPs) in WNT6 and WNT10A are associated with the risk of dental pulp calcification in orthodontic patients. This cross-sectional study followed the "Strengthening the Reporting of Genetic Association Studies" (STREGA) guidelines. Panoramic radiographs (pre- and post-orthodontic treatment) and genomic DNA from 132 orthodontic patients were studied. Dental pulp calcification (pulp stones and/or pulp space narrowing) was recorded in upper and lower first molars. The SNPs in WNT6 and WNT10A (rs7349332, rs3806557, rs10177996, and rs6754599) were assessed through genotyping analysis using DNA extracted from buccal epithelial cells. The association between pulp calcification and SNPs were analyzed using allelic and genotypic distributions and haplotype frequencies (p<0.05). Prevalence of dental pulp calcification was 42.4% in the 490 studied molars. In the genotypic analysis, the SNPs in WNT10A showed a statistically significant value for molar calcification (p = 0.027 for rs1017799), upper molar calcification (p = 0.040 for rs1017799) (recessive model), and molar calcification (p = 0.046 for rs3806557) (recessive model). In the allelic distribution, the allele C of the SNP rs10177996 in WNT10A was associated with molar calcifications (p = 0.042) and with upper first molar calcification (p = 0.035). Nine combinations of haplotypes showed statistically significant value (p<0.05). The findings of this study indicates that SNPs in WNT10A and WNT6 are associated with dental pulp calcification in molars after orthodontic treatment and may be considered as biomarkers for dental pulp calcification.

Association between the prevalence of pulp stones and calcified atherosclerotic plaques: a systematic review and meta-analysis

OBJECTIVE

To evaluate the association between the prevalence of pulp stones (PS) in permanent teeth and calcified atherosclerotic plaques (CAP).

METHODS

An electronic search was performed in 10 databases to locate observational studies that investigated the association between PS in permanent teeth and CAP, published until March 2022. Two reviewers performed the search, selection and extraction of data from eligible studies. The individual risk of bias of eligible studies was assessed using the JBI Critical Appraisal Tools. The meta-analysis was conducted using fixed and random effects and odds ratio (OR) as an effect measure with a 95% confidence interval (CI). The heterogeneity between the studies was quantified using the I² test. The certainty of evidence was evaluated using the GRADE approach.

RESULTS

The electronic search resulted in 2968 records, of which only 7 studies were considered eligible. The total sample consisted of 3770 participants from 5 countries. All studies showed biases of confounding factors and exposure assessment. Based on six studies and with very low certainty of evidence, the meta-analysis showed that patients with PS were more likely to also have CAP in carotid or coronary arteries (OR: 1.70; 95% CI: 1.21; 2.38, I² = 0%).

CONCLUSIONS

Limited evidence suggests that there is a positive association between the prevalence of PS in permanent teeth detected using panoramic radiography and CAP in the coronary or carotid arteries.

Soft Microdenticles on Artificial Octopus Sucker Enable Extraordinary Adaptability and Wet Adhesion on Diverse Nonflat Surfaces

Bioinspired soft devices, which possess high adaptability to targeted objects, provide promising solutions for a variety of industrial and medical applications. However, achieving stable and switchable attachment to objects with curved, rough, and irregular surfaces remains difficult, particularly in dry and underwater environments. Here, a highly adaptive soft microstructured switchable adhesion device is presented, which is inspired by the geometric and material characteristics of the tiny denticles on the surface of an octopus sucker. The contact interface of the artificial octopus sucker (AOS) is imprinted with soft, microscale denticles that interact adaptably with highly rough or curved surfaces. Robust and controllable attachment of the AOS with soft microdenticles (AOS-sm) to dry and wet surfaces with diverse morphologies is achieved, allowing conformal attachment on curved and soft objects with high roughness. In addition, AOS-sms assembled with an octopus-arm-inspired soft actuator demonstrate reliable grasping and the transport of complex polyhedrons, rough objects, and soft, delicate, slippery biological samples.

Morphological study of the oral denticles of the porbeagle shark Lamna nasus

Oral denticles of sharks are composed by a crown, dentine covered by a layer of enameloid and pulp cavity, the same structure of the dermal denticles found across the body surface of most elasmobranchs. In addition, oral papillae and taste buds are distributed among denticles within the oropharyngeal cavity, playing a fundamental role for tasting as part of the chemosensory system of fishes. Scanning electron microscopy (SEM) has been employed as an important tool for the study of dermal denticles and other structures, as well as histology and more recently computed tomography (CT) scan analysis. Herein, the authors used two methods for the study of the morphology of the oropharyngeal cavity of Lamna nasus (Lamniformes), an oceanic and pelagic shark: SEM and CT scan. The general morphology of oral denticles studied herein is related to abrasion strength as they are diamond-shaped, lack lateral cusps and have less pronounced ridges. In addition, smooth ridges and broad rounded denticles could be related to prevent abrasion during food consumption and manipulation. Oral papillae had a round shape and were observed only under SEM. The densities of papillae were estimated in 100 per cm² , whereas denticles were 1760 and 1230 cm² over the dorsal and ventral regions, respectively. The high numbers of denticles are inversely proportional to papillae density; denticles seem to restrict papillae distribution. Regarding the differences between methodologies, under SEM, only the crown was visualized, as well the papillae, allowing the estimation of size and density of both structures. Nonetheless, under CT scan, the whole components of denticles were clearly visualized: different views of the crown, peduncle, basal plate, and pulp cavity. On the contrary, oral papillae were not visualized under CT due to the tissue preparation. Furthermore, both methods are complementary and were important to extract as much information as possible from denticles and papillae.

Three scleral ossicles in the West African Denticle herring Denticeps clupeoides (Clupeiformes: Denticipitidae)

The eyes of teleostean fishes typically exhibit two ossifications, the anterior and posterior sclerotics, both associated with the scleral cartilage. The West African Denticle herring Denticeps clupeoides has three scleral ossifications, including the typical two associated with the scleral cartilage (anterior and posterior sclerotic) and a third ossification (Di Dario's ossicle), spatially separated from the scleral cartilage and located within the anteromedial wall of the sclera. The medial rectus muscle inserts on the medial surface of Di Dario's ossicle, suggesting that this third sclerotic may play a role in forward rotation of the eye in this surface feeding fish.

Hydrodynamic efficiency in sharks: the combined role of riblets and denticles

We investigate the influence of smooth and ribletted shark skin on a turbulent boundary layer flow. Through laser Doppler anemometry (LDA) the role of riblets in combination with the shark skin denticle is established for the first time. Our results show that smooth denticles behave like a typical rough surface when exposed to an attached boundary layer. Drag is increased for the full range of tested dimensionless denticle widths,w⁺≈ 25-80, wherew⁺is the denticle width,w, scaled by the friction velocity,u_τ, and the kinematic viscosity,ν. However, when riblets are added to the denticle crown we demonstrate there is a significant reduction in drag, relative to the smooth denticles. We obtain a modest maximum drag reduction of 2% for the ribletted denticles when compared to the flat plate, but when compared to the smooth denticles the difference in drag is in excess of 20% forw⁺≈ 80. This study enables a new conclusion that riblets have evolved as a mechanism to reduce or eliminate the skin friction increase due to the presence of scales (denticles). The combination of scales and riblets is hydrodynamically efficient in terms of skin-friction drag, while also acting to maintain flow attachment, and providing the other advantages associated with scales, e.g. anti-fouling, abrasion resistance, and defence against parasites.

Mechanical Resistance in Decapod Claw Denticles: Contribution of Structure and Composition

The decapod crustacean exoskeleton is a multi-layered structure composed of chitin-protein fibers embedded with calcium salts. Decapod claws display tooth-like denticles, which come into direct contact with predators and prey. They are subjected to more regular and intense mechanical stress than other parts of the exoskeleton and therefore must be especially resistant to wear and abrasion. Here, we characterized denticle properties in five decapod species. Dactyls from three brachyuran crabs (Cancer borealis, Callinectes sapidus, and Chionoecetes opilio) and two anomuran crabs (Paralomis birsteini and Paralithodes camtschaticus) were sectioned normal to the contact surface of the denticle, revealing the interior of the denticle and the bulk endocuticle in which it is embedded. Microhardness, micro- and ultrastructure, and elemental composition were assessed along a transect running the width of the cuticle using microindentation hardness testing, optical and scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS), respectively. In all species tested, hardness was dramatically higher-up to ten times-in the denticle than in the bulk endocuticle. Likewise, in all species there was an increase in packing density of mineralized chitin-protein fibers, a decrease in width of the pore canals that run through the cuticle, and a decrease in phosphorous content from endocuticle to denticle. The changes in hardness across the cuticle, and the relationship between hardness, calcium, and magnesium content, however, varied among species. Although mechanical resistance of the denticles was exceptionally high in all species, the basis for resistance appears to differ among species. STATEMENT OF SIGNIFICANCE: Understanding the diverse mechanisms by which animals attain exceptionally high mechanical resistance may enable development of novel, biologically inspired materials. Decapod crustacean claws, and particularly the tooth-like denticles that these claws display, are of interest in this regard, as they must be especially resistant to wear. We assessed mechanical, elemental, and structural properties of the claw cuticle in five decapod species. Without exception, microhardness was dramatically higher in the denticle than in the bulk endocuticle. Multivariant statistical analyses, however, showed that the relationships among microhardness, elemental content, and structural variables differed among species. Such patterns likely result from strong evolutionary pressure on feeding and defensive structures and a trade-off between mechanical properties and energetic cost of exoskeleton formation.

Endodontic access

Access preparation may be the single most important mechanical phase of root canal therapy. This article reviews the essential components of good access design and research intended to help guide treatment planning and clinical treatment, with an emphasis on using available information to develop a three-dimensional mental image of the tooth prior to endodontic access, allowing for safe and efficient endodontic therapy. Guidelines for developing an ideal access form, locating small and calcified canals, and avoiding iatrogenic mishaps are presented. Specific tools for efficient access preparation are identified and explained; in addition, case selection and indications for possible referral to a specialist are discussed.

Conservative treatment of an ankylosed tooth after delayed replantation: a case report

An 8-year-old boy sustained avulsion of his upper right maxillary central incisor and lateral luxation of his upper left maxillary incisors. Subsequently, the upper right maxillary central incisor developed replacement resorption, and both upper left maxillary incisors developed pulpal canal obliteration. In the ankylosed tooth, decoronation procedure was performed, and in the 44-month follow-up period the involved alveolar site showed vertical apposition of bone and continuing replacement resorption. Decoronation is a surgical procedure that allows preservation of the bone volume for the future, avoiding aesthetic disturbances and more aggressive treatments in cases where other therapeutic alternatives are not feasible.

Kenny-Caffey Syndrome: oral findings and 4-year follow-up of overlay denture therapy

Kenny-Caffey Syndrome (KCS) is an extremely rare osteosclerotic bone dysplasia associated with hypocalcemia and ocular abnormalities. Although the condition is well reported in the medical literature, dental manifestations have not been discussed in great detail. The purpose of this report is to present specific oral features and prosthetic management in a KCS patient. Overlay dentures were utilized in the management of low vertical dimension of occlusion, congenital absence of several permanent teeth, and problems associated with function and esthetics. Results of the 4-year follow-up overlay denture therapy are presented.

Platelet-derived growth factor exerts disparate effects on odontoblast differentiation depending on the dimers in rat dental pulp cells

Platelet-derived growth factor (PDGF) has recently been demonstrated to control the expression of alkaline phosphatase and proteoglycan synthesis of odontoblastic cells in dental pulp tissues. Although PDGF appears to be closely related to dentinogenesis, much about the mode of action of PDGF on odontoblast differentiation remains unclear. In this study, we examined the effects of three PDGF dimers (PDGF AA, AB, and BB) on odontoblastic differentiation of dental pulp cells in long-term mineralized cultures. Dental pulp cells isolated from rat lower incisors were continuously treated with each of PDGF AA, AB, and BB in separate cultures for 20 days. The three PDGF dimers suppressed alkaline phosphatase activity, osteocalcin and calcium content, and the formation of dentin-like nodules. The expression of mRNA for dentin sialoprotein (DSP) in the cells was inhibited by PDGF AA treatment, whereas PDGF AB and BB treatment stimulated the expression of DSP, even though the dentin-like nodule formation was inhibited. Although the effects of PDGF on odontoblastic differentiation varied among the dimers, the cells expressed both PDGF alpha and beta receptors, whose quantities were similar. These results suggest that PDGF exerts diverse effects on odontoblastic differentiation depending on its dimeric form. These in vitro findings explain, at least in part, the in vivo action of PDGF in dentinogenesis during the repair process of damaged dental pulp.

Influence of resinous monomers on the differentiation in vitro of human pulp cells into odontoblasts

Odontoblasts are highly differentiated postmitotic cells, which under pathological conditions such as carious lesions and dental injuries may degenerate and be replaced by other pulp cells. A recent work showed that this physiological event can be reproduced in an in vitro assay system. The purpose of the present study was to evaluate the effects of resinous monomers on odontoblast differentiation in vitro. Pulp cores from extracted human third molars were cultured with beta-glycerophosphate (2 mM) and used to evaluate the effects of TEGDMA, HEMA, UDMA, and Bis-GMA on the differentiation of pulp fibroblasts into odontoblasts. The effect of the monomers was studied by evaluating the expression of several odontoblast specific genes. In the absence of monomers, mineral nodule formation was observed. Pulp cells contributing to the nodule formation synthesized type I collagen, osteonectin, and dentin sialoprotein (DSP). In addition, Fourier transform infrared microspectroscopy showed that the mineral and organic composition of the nodules were characteristic of dentin. When the monomers were added at nontoxic concentrations, the effects of HEMA and Bis-GMA were more evident than that of TEGDMA and UDMA on collagen 1, osteonectin, and DSP expression. However, all monomers significantly decreased DSP expression and completely inhibited the mineral nodule formation.

Intentional replantation of a mandibular molar with calcified canal: a case report

Intentional replantation is an accepted endodontic technique for treating teeth in which both conventional and/or surgical endodontic treatments are not recommended. A rare case using intentional replantation technique on one mandibular molar has been successfully treated. This procedure was used owing to inaccessible calcified canal and pain intolerance of the patient. A thirty month post-operative evaluation revealed an asymptomatic, functional tooth with no radiographic signs of pathosis. The favorable results obtained in this case might be attributed to certain factors, such as occlusal adjustment prior to replantation, maintaining asepsis during replantation, no-damaging pressure during extraction, use of noneugenol periodontal packing, preservation of the vitality of the periodontal ligament, a minimal extraoral period, non-rigid splinting, apicoectomy and retrograde amalgam filling were done for hermetic apical seal. Intentional replantation may be limited to those cases when conventional endodontic therapy is not possible, but may be a treatment alternative to maintain the dentition and save an otherwise hopeless tooth.

Regional odontodysplasia: report of three cases

Regional odontodysplasia is a developmental anomaly of dental tissues with characteristic clinical, radiographic, and histologic appearances. It most commonly affects the maxillary anterior teeth of both the primary and permanent dentition, and occurs in females twice as often as in males. The pathogenesis is unknown. The clinical and histopathologic findings of regional odontodysplasia in three patients are discussed.

Symmetrical pulp obliteration in mandibular first molars

Pulp obliteration is an extremely rare morphological type of pulp calcification, with calcified material completely occupying the pulp chamber and root canal spaces. The etiology of pulp obliteration may be trauma or systemic diseases such as secondary hyperparathyroidism. Pulp obliteration may also be seen in dental anomalies such as dentinogenesis imperfecta and dentinal dysplasia. In cases of pulp obliteration with periapical disease, the preferred treatment is surgery, while calcified canals without symptoms or periapical lesions are best left untreated.

Pulp responses to two strains of bacteria isolated from human carious dentine (L. plantarum) (NCTC 1406) and S. mutans (NCTC 10919)

A series of studies has been conducted in which monoinfected gnotobiotic rats were used to study the responses of the dental pulp to micro-organisms isolated from carious lesions in dentine. In this study pulp responses to L. plantarum (formerly odontolyticus) (NCTC 1406) in pure culture and in combination with S. mutans (NCTC 10919) are reported. The incidence of inflammation/necrosis/dentine bridge formation observed in animals monoinfected with L. plantarum was similar to that reported in previous germ-free studies. There was a greater incidence of dentine bridge formation in rats monoinfected with L. plantarum compared with those monoinfected with S. mutans. When the two organisms were combined, periapical inflammation was observed in 14% of the teeth examined after 28 days, but there was no significant difference in the incidence of dentine bridge formation. Considerable variation in the density of staining of the two microorganisms in histological sections was observed.

Anatomical barriers in endodontics

Endodontic therapy can be challenging at the diagnostic and technical levels. The more one can advance one's accomplishments, the more that would-be barriers cease to be so. Difficult aspects of tooth isolation and assessment of root integrity can be rendered less problematic by some relatively simple methods. Gaining a clear awareness of the internal layout of a coronal chamber and any possible inclusions can be assisted by use of a modified endodontic explorer. It can be usefully employed to resolve with certainty the common dilemma of whether openings at the base of a molar or maxillary premolar coronal access cavity are exposures in the pulp chamber roof or orifices in the chamber floor. Locating and then gaining full working length entry into partly calcified canals, even when they are not radiographically discernible, remains one of the difficult tasks in endodontic therapy, but methods can be implemented that maximize their successful negotiation and management. The use of fine engine-driven reamers, but absolutely restricted to a reciprocating action handpiece, is described.

A review of aging of dental components and a retrospective radiographic study of aging of the dental pulp and dentin in normal teeth

A review of aging of dental components is followed by a clinical radiographic study. Patients received radiographs at 5-year intervals with a 10-year minimum followup. Data obtained were age, gender, tooth, and systemic diseases. Measurements taken were tooth length, coronal length, apical length, cervical width, midroot width, and apical width. Root canal shrinkage was calculated vertically, horizontally, and as a combination (vertical and horizontal). Results showed statistically significantly more shrinkage in men, the elderly, and people with calcification-related diseases. Shrinkage increased with advancing age. With further studies, radiographically determined root canal measurements could prove useful in anthropology, forensics, and as a biomarker of aging.

Scanning electron microscopic study of pulp stones in human permanent teeth

Scanning electron microscopy was used to examine pulp stones which are small calcified formations found in the coronal and/or radicular part of the dental pulp. Pulp stones range considerably in size and shape. Most are round or oval but others can be irregular and may correspond to a reduced duplicate of the pulp chamber anatomy. Both free and attached pulp stones were observed. The surface aspect was variable and frequently exhibited large resorption zones. Three characteristic features were observed on fractures: a) no characteristic organization where the mineralized mass is compact and homogeneous, b) a concentric architecture around an initiating central core, and c) a linear orientation along the pulp axis showing mineralized fibres and vessels. The findings suggest that the presence or absence of tubules should not be the sole factor for denticle classification since tubules can be also observed in "false" pulp stones. Cellular oval lacunae connected by long extensions were also found. Various stages of mineralization were seen, in particular, a deposition of fine needle shaped crystals on a collagenous matrix, and the fusion of numerous small calcospherules to the mineralized mass.

Unusual case of general pulp calcification (pulp stones) in a young Greek girl

An unusual case of generalized pulp calcification is reported in a 14-year-old Greek girl. Radiographic examination revealed large pulp stones in all permanent teeth located in the pulp chamber and sometimes extending to the coronal portion of the root canal. The patient's dental, medical and family history, as well as the findings from the clinical examination were non-contributory. Biochemical analysis of one pulp stone removed from the right maxillary central incisor revealed large amounts of urates, proteins and phospholipids, but a blood test of the patient showed no metabolic disturbance. Therefore, it is suggested that this unusual case may be of idiopathic origin.

Comparison of the radiographic appearance of root canal size to its actual diameter

Clinically, the apparent radiographic diameter size does not always seem to correspond to the true canal size. The objective of this study was to compare canal size on periapical radiographs with the actual canal diameter as determined histologically. Periapical radiographs were exposed on 36 teeth on 5 human cadavers. Mesial-to-distal boundaries of canals were measured in the cervical, middle, and apical thirds. The teeth were extracted, the roots histologically processed, and cross-sections made in the cervical, middle, and apical thirds. Measured values of diameter from radiographs were compared with true canal widths as measured from the corresponding level of histological sections by using a correlated t test. All sections of all roots demonstrated a canal histologically, although some regions had no canal visible radiographically. In general, there was statistically no difference (p less than 0.001) between the histological and radiographic measurements even when pulpal calcifications were present. However, in some roots there were marked discrepancies between radiographs and histological sections as to canal diameter.

[Histopathologic study on the application of synthetic hydroxyapatite and alpha-tricalcium phosphate for vital pulpotomy]

Hydroxyapatite (HAp) and alpha-Tricalcium phosphate (alpha-TCP) are generally known as materials biocompatible to human tissue. In this study, the adaptation of HAp and alpha-TCP as a pulpotomy agent was studied histopathologically. In this study, HAp granules with a sintering temperature of 1,200 degrees C and sieved through a 37 micron sieve, and APATITE LINER TYPE I (Sankin CO.) as alpha-TCP were used. Calcium hydroxide served as a control. The physical properties of these experimental materials were evaluated and the reaction of pulp tissue to the materials was examined histolongically in dogs. alpha-TCP mixed with saline solution showed more homogeneous and higher viscosity than HAp mixed with saline solution. When alpha-TCP was applied on the site of exposure of a pulp following pulpotomy, the mechanically harmed pulp tissue was healed earlier than when HAp was applied. A hard tissue was formed earliest when calcium hydroxide was used, and then in the order of alpha-TCP and HAp. When HAp was applied, osteodentin was formed and when alpha-TCP was applied, dentin was formed on the site of exposure of a pulp following pulpotomy. When HAp or alpha-TCP was applied, the calcification in the initial stage was not observed. The calcification in initial stage was observed when calcium hydroxide was applied. These results suggest that alpha-TCP is useful as a pulpotomy agent.

Calcification of dentinal collagen by cultured rabbit periosteum: the role of alkaline phosphatase

Periostea were dissected from 1-2 weeks old rabbit calvaria and folded around decalcified and extracted bovine dentin matrix slices (DMS). The cocultures were grown in serum-containing medium supplemented with beta-glycerophosphate or other organic phosphate esters. [45Ca]-uptake measurements indicated that the DMS calcified. Initiation of the calcification process was associated with alkaline phosphatase activity and could be prevented by adding the inhibitor L-levamisole to the culture medium. Using [32P]-adenosine-monophosphate as a substrate for phosphatase activity it was demonstrated that very little, if any, phosphate was utilized for the phosphorylation of higher molecular weight substances. The results suggest that over 99% of the phosphate produced was laid down in inorganic form. Further, it was noted that mineral deposition in the DMS was accompanied by the simultaneous inclusion of methylene blue and PAS-positive substances whose nature, origin and function remain to be determined. The results lend support to the theory that alkaline phosphatase is involved in the initiation of calcification processes by raising the local concentration of phosphate ions.

In vivo recalcification of dentin demineralized by citric acid

Acid-treatment of root surfaces as adjunct to periodontal reconstructive surgery may have deleterious effects on that part which remains in a supragingival location after healing. The present experiment aimed to examine whether recalcification of such root surfaces may occur. Cylindrical blocks of root dentin were prepared for 10 premolars, treated with citric acid and mounted in acrylic specimen holders which were worn in the mouth continuously for 14 d by two test subjects. The specimens were then sectioned and microradiographs produced. The citric acid had produced a completely demineralized surface zone in the root dentin and the subjacent hard tissue showed a zone of partially reduced mineral content. Following exposure to the oral cavity, the demineralized surface layer appeared unchanged in width. The subjacent zone, however, had been reduced in width in all instances when compared with control specimens from the same teeth.

[The use of organic bone matrix as material for direct pulp capping]

The effect of bone matrix soaked in thyrocalcitonin on vitally amputated pulp was studied in beagle dogs with light and electron microscopy. All treated teeth were vital after eight weeks; the area of implantation was densely populated with cells. Formation of hard tissue differing from normal dentinogenesis had begun.

The effect of wear on the cheek teeth and associated dental tissues of the lizard Uromastix aegyptius (Agamidae)

Serial coronal sections of the teeth and their surrounding tissues in the agamid lizard, Uromastix aegyptius, were examined with the light microscope in order to determine how these structures change as the teeth wear. Because new teeth are added only at the posterior end of the tooth row and older teeth are not replaced, the series of sections included the youngest as well as the oldest teeth. Two types of changes occur as the teeth become older: bone under the teeth changes from cancellous to compact, and the pulp chamber of the tooth is obliterated. Although the labial surface of the dentary lacks a periosteal covering and some of the bone lacks any covering at all, it remains functional throughout the life of the animal.

Structure and histogenesis of tooth plates in Sagenodus inaequalis Owen considered in relation to the phylogeny of post-Devonian dipnoans

The histology of tooth plates of Sagenodus inaequalis has been investigated to obtain information on the histogenesis of the tissue. The histological mechanisms of growth and replacement of the tooth plate are described in terms of an increase in area of the tooth plate by addition of denticles to the lateral margins of the ridges, replacement of worn dentine at the tritoral surface by basal growth of dentine and invasive growth of dentine into the surrounding bone at the anterior and medial margins. The histogenesis of a specialized character for dipnoans is described, namely hypermineralized dentine, or petrodentine, within the tooth plates. This has placed an advanced character further back in the phylogenetic organization of dipnoans than was previously recognized. The implications of these observations are discussed in relation to proposed phylogenies and previous observations on tooth plates of other dipnoans. It is concluded that Sagenodus inaequalis shared a common ancestor with both the ceratondontids and the lepidosirenids. A sequence is proposed for the phyletic relationship of tooth plate-bearing dipnoans. From a consideration of the features of histogenesis of this specialized dentine, the alternative terminologies are reviewed and petrodentine (Lison 1941) chosen for the hypermineralized dentine and syndentine (Thomasset 1928) as the collective term for the entire mass of dentine in the tooth plate.

Long-term follow-up and evaluation of transplantation of fully developed teeth

Five cases of transplantation of fully developed third molars to second or first molar sites have been reported. Three of the transplants were in the mandibular molar region and two were in the maxillary molar region. There has been long-term follow-up and evaluation of the patients in these cases up to 13 years postoperatively. None of the patients had any complaint about the transplanted tooth at the long-term follow-up visit. In all five cases, at the long-term follow-up visit, the periodontal tissues were in excellent condition and there was growth of new attachment, as demonstrated by lamina dura and periodontal membrane space in the follow-up radiographs, deposition of secondary calcification of varying amounts within the root canals and pulp chamber, and regeneration of bone in the periapical and lateral areas. There was very little, if any, resorption demonstrated in any of these five cases. The ages of patients ranged from 17 to 23 years at the time of transplantation. Regeneration of the buccal plate was demonstrated by photographs in one of the two cases where there was surgical exposure of the region of the buccal plate at a postoperative follow-up visit.

Radiographic manifestations of an unusual combination Types I and Type II dentin dysplasia

Dentin dyslasia is a rare autosomal dominant hereditary variant of dentinogenesis imperfecta. The primary defect is mesodermal and involves the dentin. Two types (Type I and Type II) of dentin dysplasia have been described previously. The current case presents radiographic findings which include characteristics common to both types. It is proposed that either a third type (Type III) be recognized or the variability of the developmental defect precludes definitive subclassification.

[Report of case of opalescent dentin. A polariation optic and microradiographic study on a pulpless tooth]

Ground sections prepared from a molar (-7) with opalescent dentine were investigated by the means of polarizing microscopy and microradiography. Histological and clinical findings are discussed. Unfortunately, heredity could not be surely determined. But in all experience we are shure, that a hereditary mutation, recently or earlier in a generation occured, was the cause also in this case.

Repair characteristics of root fractures in permanent anterior teeth

A follow-up study was made of repaired root fractures in 51 permanent anterior teeth, with a mean observation period of 6 years. The material was subdivided into three repair types (Figs. 1-3): Type 1 - invisible or hardly discernible fracture line (15 teeth), Type 2 - fragments separated by a narrow radiolucent line and peripheral rounding of the fracture edges (33 teeth), and Type 3 - fragments separated by a distinct bony bridge (3 teeth). The majority of repaired teeth gave a normal or slightly decreased response to electric pulp tests and the mobility was physiologic or slightly increased. Reduced transparency or slight yellowish discoloration was observed in 14 teeth. The most conspicuous radiographic finding was pulp obliteration which occurred in 86%. Two different patterns were observed: (1) partial obliteration located in the apical fragments and the fracture area, and extending 0.5-4 mm into the coronal fragment, and (2) progressive obliteration of the entire pulp cavity ending with almost total obliteration. Pulp necrosis did not develop as a sequel to progressive obliteration in any case. Several different characteristics of the fracture influenced the repair pattern, the most important being the degree of fragment dislocation and mobility, stage of root development and localization of the fracture. Correlation between type of repair and various treatment procedures was observed only with regard to reduction.

Long-term prognosis of 66 permanent anterior teeth with root fracture

A longitudinal clinical and radiographic follow-up study was made of all permanent teeth with root fractures referred to the Oslo University Department of Pedodontics between 1953 and 1972 (n = 66). The material included 51 patients aged 6-21 years. The mean observation period was 5.2 years, ranging from 1 to 19 years. The present report documents background data and the long-term results. Two teeth with exarticulation of the coronal fragments (3%) were immediately extracted. Repair of the fracture area occurred in 51 teeth (77%). Pulp necrosis was found in 13 teeth (20%), nine of which were successfully treated endodontically; only four teeth had to be extracted. Several factors were found to influence the prognosis, most notably the degree of dislocation of the coronal fragment. The localization of the fracture influenced repair only slightly. Despite somewhat increased mobility in some cases, the longevity of teeth with fractures even in the coronal third of the root was not significantly shortened. It is concluded that when optimally treated by repositioning, fixation and relief of occlusion, anterior teeth with root fracture have a favorable prognosis. Even when pulp necrosis occurs, the long-term prognosis is good.