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This case study describes the diagnosis and treatment of a deciduous left maxillary canine tooth root that had been displaced into the pulp of the developing permanent left maxillary canine tooth in a 23-month-old female neutered Cavalier King Charles Spaniel. The patient was initially presented for bilateral persistent deciduous maxillary canine teeth extraction. Seventeen months later the permanent left maxillary canine tooth was found to be non-vital and tooth development had ceased prior to apical closure. Radiographs revealed a radio-opaque dentine-like structure and straight line centrally within the pulp of the permanent tooth. The displacement of the deciduous tooth into the developing permanent tooth was confirmed. This unusual potential complication should be considered when performing deciduous teeth extraction. [ABSTRACT FROM AUTHOR]

Our prospective study analyzed clinical, radiographic, and histological characteristics of 102 intrinsically stained teeth. Sixty-nine dogs ranging from one to fifteen years of age were included in this study. Little more than half of the intrinsically stained teeth had no evidence of coronal injury (53.9%, 55/102). We found that most intrinsically stained teeth were histologically nonvital (87.6%, 85/97) and approximately 2/3 of these (57.7%, 56/97) had no histological endodontic or periodontal inflammation at the time of evaluation. Radiographic evidence of endodontic disease was present in 57% (58/102) of the intrinsically stained teeth. Radiographic evidence of periodontal disease was present in 48% (49/102) of intrinsically stained teeth and 28% (29/102) had radiographic evidence of tooth resorption. 18.6% (19/102) of intrinsically stained teeth were radiographically normal. Evidence of pulp necrosis was common in these intrinsically stained teeth, while only occasional teeth (12.4%, 12/97) had histologically confirmed pulpitis. All teeth with radiographic evidence of periapical lucency had pulp necrosis. Based on our histological findings, the majority of intrinsically stained teeth 87.6% are truly nonvital. [ABSTRACT FROM AUTHOR]

The canonical Wnt/β-catenin signaling pathway is crucial for reparative dentinogenesis following tooth damage, and the modulation of this pathway affects the rate and extent of reparative dentine formation in damaged mice molars by triggering the natural process of dentinogenesis. Pharmacological stimulation of Wnt/β-catenin signaling activity by small-molecule GSK-3 inhibitor drugs following pulp exposure in mouse molars results in reparative dentinogenesis. The creation of similar but larger lesions in rat molars shows that the adenosine triphosphate (ATP)-competitive GSK-3 inhibitor, CHIR99021 (CHIR), and the ATP noncompetitive inhibitor, Tideglusib (TG), can equally enhance reparative dentine formation to fully repair an area of dentine damage up to 10 times larger, mimicking the size of small lesions in humans. To assess the chemical composition of this newly formed dentine and to compare its structure with surrounding native dentine and alveolar bone, Raman microspectroscopy analysis is used. We show that the newly formed dentine comprises equal carbonate to phosphate ratios and mineral to matrix ratios to that of native dentine, both being significantly different from bone. For an effective dentine repair, the activity of the drugs needs to be restricted to the region of damage. To investigate the range of drug-induced Wnt-activity within the dental pulp, RNA of short-term induced (24-h) molars is extracted from separated roots and crowns, and quantitative Axin2 expression is assayed. We show that the activation of Wnt/β-catenin signaling is highly restricted to pulp cells in the immediate location of the damage in the coronal pulp tissue with no drug action detected in the root pulp. These results provide further evidence that this simple method of enhancement of natural reparative dentinogenesis has the potential to be translated into a clinical direct capping approach. [ABSTRACT FROM AUTHOR]

Regenerative endodontics has been defined as "biologically based procedure designed to replace damaged structures, including dentin and root structures, as well as cells of the pulp--dentin complex." This is an exciting and rapidly evolving field of human endodontics for the treatment of immature permanent teeth with infected root canal systems. These procedures have shown to be able not only to resolve pain and apical periodontitis but continued root development, thus increasing the thickness and strength of the previously thin and fracture-prone roots. In the last decade, over 80 case reports, numerous animal studies, and series of regenerative endodontic cases have been published. However, even with multiple successful case reports, there are still some remaining questions regarding terminology, patient selection, and procedural details. Regenerative endodontics provides the hope of converting a nonvital tooth into vital one once again. [ABSTRACT FROM AUTHOR]

Context: Sea buckthorn (Hippophae rhamnoides L.) as a traditional Chinese medicinal plant has various uses in Xinjiang. Objective: A reversed-phase rapid-resolution liquid-chromatography method with diode array detector was developed for simultaneous determination of protocatechuic acid, rutin, quercetin, kaempferol, and isorhamnetin in the pulp and seed of sea buckthorn, a widely used traditional Chinese medicine for promoting metabolism and treating scurvy and other diseases. Settings and design: Compounds were separated on an Agilent ZORBAX SB-C18 column (4.6 mm × 250 mm, 5 μm; USA) with gradient elution using methanol and 0.4% phosphoric acid (v/v) at 1.0 mL/min. Detection wavelength was set at 280 nm. Materials and Methods: The fruits of wild sea buckthorn were collected from Wushi County in Aksu, Xinjiang Province. Statistical performances: The RSD of precision test of the five compounds were in the range of 0.60-2.22%, and the average recoveries ranged from 97.36% to 101.19%. Good linearity between specific chromatographic peak and component qualities were observed in the investigated ranges for all the analytes (R2 > 0.9997). Results: The proposed method was successfully applied to determine the levels of five active components in sea buckthorn samples from Aksu in Xinjiang. Conclusions: The proposed method is simple, fast, sensitive, accurate, and suitable for quantitative assessment of the pulp and seed of sea buckthorn. [ABSTRACT FROM AUTHOR]

Differences between pulp repair and regeneration guide different strategic options. After mild carious dentin lesions, odontoblasts and Hoehl’s cells are implicated in the formation of reactionary dentin. Reparative dentin formation and/or pulp regeneration after partial degradation is under the control of pulp progenitors. A series of questions arise from recent researches on tissue engineering. In this series of questions, we compare the therapeutic potential of pluripotent embryonic and adult stem cells, both being used in cell-based dental therapies. Crucial questions arise on the origin of stem cells and the localization of niches of progenitors in adult teeth. Circulating progenitor cells may also be candidate for promoting pulp regeneration. Then, we focus on strategies allowing efficient progenitors recruitment. Along this line, we compare the potential of embryonic stem cells versus adult stem cells. Re-programming adult pulp cells to become induced pluripotent stem cells constitute another option. Genes, transcription factors and growth factors may be used to stimulate the differentiation cascade. Extracellular matrix molecules or some bioactive specific domains after enzymatic cleavage may also contribute to the formation of an artificial pulp and ultimately to its mineralization. [ABSTRACT FROM PUBLISHER]

The reconstruction of digital pulp defects is still a challenge in hand surgery. Several reconstructive techniques are available, but in some cases, their advancement capacities are not sufficient for the flap to cover the whole defect. The Gigogne flap is a new, very simple and safe technique. It consists of harvesting two cutaneous flaps successively on the same neurovascular digital palmar bundle. The first plasty may be chosen among the well-known flaps usually applied in pulp reconstruction. The second plasty, the Gigogne flap, is an advancement VY plasty done on the main cutaneous paddle of the first proximal flap. We performed 15 Gigogne flaps in 13 patients, who suffered zone II and III digital pulp amputations. The Gigogne flap increased the advancement capacity of the proximal flap as well as restoring the physiological pulp fatty pad, thus reconstructing a functional and aesthetic fingertip. [ABSTRACT FROM AUTHOR]

After pulp amputation, complete pulp healing requires not only reparative dentin production but also fibroblast proliferation, nerve fiber growth, and neoangiogenesis. This study was designed to investigate the role of pulp fibroblasts in angiogenesis. Human pulp fibroblasts from third molars co-cultured with human umbilical vein endothelial cells induced the organization of endothelial cells and the formation of tubular structures corresponding to capillaries in vivo. The direct contact between both cells was not necessary to induce angiogenesis, and the observed effect was due to soluble factors. This was confirmed with neutralizing antibodies against FGF-2 and VEGF, which decreased the angiogenic effects of these soluble factors. Immunohistochemistry showed that both FGF-2 and VEGF were expressed in human dental pulp fibroblasts, and this expression increased after injury. These results suggest that the pulp fibroblasts secrete angiogenic factors, which are necessary for complete pulp healing, particularly at the pulp injury site. [ABSTRACT FROM AUTHOR]

Hexachlorobenzene (HCB) was administered to female Sprague-Dawley rats in a 13-week toxicity study conducted for the National Toxicology Program (NTP). Groups of 10 rats were treated by gavage with 0.0, 0.03, 0.1, 0.3, 1.0, 3.0, 10, or 25 mg/kg HCB in corn oil 5 days/week for 13 weeks. Dose-dependent, region-specific, maxillary incisor degeneration was observed in animals given HCB at doses of 1.0 mg/kg/day and higher. Treatment with 1.0 mg/kg/day resulted in focal mesenchymal cell vacuolation and focal osteodentin formation within the pulp. Lesions were restricted to a short linear region subjacent to the odontoblast layer along the lateral aspect of the incisor at the level of the dentin-enamel interface. When observed in both incisors, lesions were bilaterally symmetric. Treatment with 3.0 mg/kg/day resulted in lateral and medial pulp lesions and focal odontoblast degeneration with dentin niche formation along the lateral incisor margin in some animals. Treatment with 10 mg/kg/day resulted in a higher incidence of lateral dentin niches and a low incidence of medial dentin niches. In animals treated with 25 mg/kg/day, a high incidence of bilaterally symmetric, lateral and medial, dentin niches were observed. The morphology and distribution of HCB-induced incisor lesions in rats are consistent with injury to a selective population of preodontoblasts. [ABSTRACT FROM AUTHOR]

Odontoblasts produce most of the extracellular matrix (ECM) components found in dentin and implicated in dentin mineralization. Major differences in the pulp ECM explain why pulp is normally a non-mineralized tissue. In vitro or in vivo, some dentin ECM molecules act as crystal nucleators and contribute to crystal growth, whereas others are mineralization inhibitors. After treatment of caries lesions of moderate progression, odontoblasts and cells from the sub-odontoblastic Höhl's layer are implicated in the formation of reactionary dentin. Healing of deeper lesions in contact with the pulp results in the formation of reparative dentin by pulp cells. The response to direct pulp-capping with materials such as calcium hydroxide is the formation of a dentinal bridge, resulting from the recruitment and proliferation of undifferentiated cells, which may be either stem cells or dedifferentiated and transdifferentiated mature cells. Once differentiated, the cells synthesize a matrix that undergoes mineralization. Animal models have been used to test the capacity of potentially bioactive molecules to promote pulp repair following their implantation into the pulp. ECM molecules induce either the formation of dentinal bridges or large areas of mineralization in the coronal pulp. They may also stimulate the total closure of the pulp in the root canal. In conclusion, some molecules found in dentin extracellular matrix may have potential in dental therapy as bioactive agents for pulp repair or tissue engineering. [ABSTRACT FROM AUTHOR]

The article examines the nature of dental caries. Since the 1940s when the acid theory of dental caries gained general acceptance, researchers seeking develop alternative theories have sometimes encountered resistance. The author discusses his own efforts to this end, and encourages oral biologists to become similarly engaged. Among the topics reviewed are the distinctions between dental caries and caries lesions in dentin, the impact of fluoride and sugar on caries progression, and protein destruction in carious dentin lesions.

Multiple intrapulpal denticles were observed in maxillary incisors of control and treated B6C3F1 mice used in a chronic inhalation study.Histologically, the denticles originated from multiple small budlike projections emanating from the epithelial sheath, immediately adjacent to the pulp chamber. The denticles were round to ovoid in shape with a central cavity surrounded by tubular dentin. Immature denticles contained epithelial cells within the central cavity, whereas mature denticles were either devoid of cells or contained cell fragments. A layer of columnar odontoblasts surrounded the outer surface of each denticle. Denticles advanced in a coronal direction as the incisors grew. With continued incisor growth, some denticles impacted the tooth wall and were associated with defects in dentinogenesis, altered tooth shape, and microfractures. Some denticles became partly or entirely incorporated into the dentin of the tooth. Intrapulpal denticle formation may represent a previously unidentified alteration that could contribute to the development of dental dysplasia in mice by interfering with normal tooth development and predisposing affected teeth to malformation and biomechanical failure with fracture. [ABSTRACT FROM AUTHOR]

The finding of expression of a muscle actin isoform, a-smooth-muscle actin (SMA), by the stromal cells of several tissues prompted this study of SMA expression by cells derived from the porcine dental pulp. The SMA content of the cells increased with time in culture. These SMA-containing cells were found to have the capability to contract a collagen-glycosaminoglycan analog of extracellular matrix in vitro. [ABSTRACT FROM AUTHOR]

Dentin has a relatively high water content due to its tubular structure. Once dentin is exposed, this intratubular water is free to move in response to thermal, osmotic, evaporative, or tactile stimuli. Fluid shifts across dentin are thought to cause sufficient shear forces on odontoblasts, nerve endings, nearby fibroblasts, and blood vessels to cause significant mechanical irritation, disruption, or damage, depending on the magnitude of the fluid shift. Even in the absence of fluid shifts, the water-filled tubules provide diffusion channels for noxious (i.e., bacterial products) substances which diffuse inward toward the pulp, where they can activate the immune system, provide chemotactic stimuli, cytokine production, and produce pain and pulpal inflammation. Viewed from this perspective, dentin is a poor barrier to external irritants. However, pulpal tissues react to these challenges by increasing the activity of nerves, blood vessels, the immune system, and interstitial fluid turnover, to make the exposed dentin less permeable either physiologically, via increased outward fluid flow, or microscopically, by lining tubules with proteins, mineral deposits, or tertiary dentin, thereby enhancing the barrier properties of dentin, and providing additional protection to pulpal tissues. These reactions involve dentin and pulp, both in the initiation of the processes and in their resolution. These responses of the dental pulp to irritation of dentin demonstrate the dynamic nature of the pulpo-dentin complex. [ABSTRACT FROM AUTHOR]

Estrogen receptors have been demonstrated in many osteogenic cell lines. Recently, we showed that estrogen deficiency induced by ovariectomy caused enhanced dentin formation in adult rats, suggesting that estrogen receptors may be present in dental tissues. Nothing is known about estrogen receptors in human teeth. We used immunohistochemical staining and immuno-blotting to demonstrate the presence of estrogen receptors in human pulp and/or the pulpo-dentinal border. Unerupted human wisdom teeth were surgically removed, frozen in liquid nitrogen, and prepared for immunological studies. Western blot analysis with monoclonal antibodies specific for human estrogen-receptor-related antigens demonstrated an approximately 29-kDa clear double band in the material scraped from the predentin-odontoblast border and in the fluid that emerged into the pulpal chamber, evidently from the odontoblasts. A weaker double band was also present in pulpal tissue samples. By immunohistochemical staining, estrogen-receptor-related antigens were visualized in the predentinal-odontoblast region and in the pulpal blood vessels. Our results suggest the presence of estrogen receptors in human teeth, and thus the previously reported enhancement of the dentin formation in rats after ovariectomy may be mediated via these receptors. [ABSTRACT FROM AUTHOR]

In familial dysautonomia (FD), a hereditary autonomic and sensory neuropathy, somatic growth is impaired. This study was conducted to explore the possibility that tooth dimensions are altered as a consequence of neural crest dysfunction known to be present in FD. Enamel, dentin, pulp, and tooth size measurements of mandibular primary and permanent molars from FD patients were compared with those of healthy controls. It was found that although tooth size in the FD patients was smaller than normal, the enamel was thicker on the occlusal table, while the pulp chamber was smaller and disproportional to tooth size. Our results suggest distorted tooth dimensions rather than a generalized growth arrest as observed in other hereditary syndromes, such as Down's or Crouzon. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses various reports within the issue on topics including the role of stem cells in craniofacial diseases, research into dental pulp-dentin regeneration, and the use of induced pluripotent stem cells in dental therapeutics.