The effect of high wear diets on the relative pulp volume of the lower molars.

OBJECTIVES: One role of dental pulp is in the upkeep and maintenance of dentine. Under wear, odontoblasts in the pulp deposit tertiary dentine to ensure the sensitive internal dental tissues are not exposed and vulnerable to infection. It follows that there may be an adaptive advantage for increasing molar pulp volume in anthropoid primate taxa that are prone to high levels of wear. The relative volume of dental pulp is therefore predicted to covary with dietary abrasiveness (in the sense of including foods that cause high degrees of wear). MATERIALS AND METHODS: We examined relatively unworn lower second molars in pairs of species of extant hominoids, cebids, and pitheciids that vary in the abrasiveness of their diet (n = 36). Using micro-CT scans, we measured the percent of tooth that is pulp (PTP) as the ratio of pulp volume to that of the total volume of the tooth. RESULTS: We found that in each pair of species, the taxa that consume a more abrasive diet had a significantly higher PTP than the closely related taxa that consume a softer diet. CONCLUSIONS: Our results point to an adaptive mechanism in the molars of taxa that consume abrasive diets and are thus subject to higher levels of wear. Our results provide additional understanding of the relationship between dental pulp and diet and may offer insight into the diet of extinct taxa such as Paranthropus boisei or into the adaptive context of the taurodont molars of Neanderthals.

Endodontium - together or separately?

Endodontium, otherwise referred to as pulp-dentin complex or endodont. This term includes two tooth tissues: dentin and pulp, which constitute a structural and functional unity. These tissues have a huge, inseparable influence on each other - the pulp (inter alia) nourishes the dentine, while the dentin forms a protective barrier for the pulp. They develop from the papillary tissue (Latin: papilladentis) from mesenchymal tissue. Nevertheless, in clinical practice this structural-functional complex is often treated as two separate tissues, and not as a whole. Adequate knowledge of the structure, function and protective mechanisms of the endodontium produces successful results in the treatment. The appropriate choice and application of the therapeutic methods and materials to the dentin secures vitality of both tissues of this complex.

Age-related morphological, histological and functional changes in teeth.

Throughout lifetime, the teeth are continuously exposed to numerous chemical and physical impacts, which cause the wear of the dental hard tissues, gingival recession and other oral changes with sometimes subsequent problems. Age-related wear of tooth surfaces reduces the dental enamel thickness and exposes deeper layers of enamel, which have different physical and chemical properties than the surface enamel. Gingival recession is the main causal factor of root caries and dentine hypersensitivity. Age-related changes in dentine include the formation of secondary dentine and the reduction in tubular lumen diameter (dentine sclerosis), which lead to a reduction in the volume of the pulp chamber. In addition to the reduction in the volume of pulp chamber, changes to the dental pulp also include dental pulp calcifications. The age-related physiological changes to the teeth should be carefully distinguished from pathological changes, especially when they induce pain or a negative impact on the oral health-related quality of life (OHRQoL) of the older individuals. Therefore, regular oral examinations coupled with early preventive measures should aim at maintaining oral health until old age.

Histological Evaluation of the Effect of Platelet-rich Plasma on Pulp Regeneration in Nonvital Open Apex Teeth: An Animal Study.

AIM: Platelet-rich plasma (PRP), which is a concentration of growth factors found in platelets, may be a suitable material for pulp regeneration. The aim of this animal study was a histological evaluation of PRP on pulp regeneration in nonvital teeth with immature apices. MATERIALS AND METHODS: A total of 40 premolar dogs' teeth were chosen for this study. After general anesthesia, the teeth were exposed, and subsequently, pulps were removed and the cavities were opened to the oral cavity. After 2 weeks, root canals were irrigated and disinfected with sodium hypochlorite with noninstrumentation technique, and triple antibiotic paste was placed inside the canals. Cavities were sealed with a temporary restoration. About 4 weeks later, canals were irrigated again and the teeth were randomly divided into three groups. Bleeding was evoked with overinstrumentation, then experimental materials for each group [PRP, mineral trioxide aggregate (MTA), and parafilm respectively] were placed over the bleeding, and orifices were sealed with MTA and glass ionomer. After 3 months, dogs were sacrificed and the teeth were separated from the jaws and sections prepared for histological evaluation. RESULTS: Regeneration was shown in 44.7% of the samples. About 47.3% of the samples in the MTA group and 42.1% of the samples in the PRP group showed regeneration; however, no regeneration was observed in the parafilm group. Chi-square test showed no significant difference between groups I and II. The soft regenerative tissue included pulp-like tissue and vessels. Mineralized regenerative tissue included cementum-like, periodontal ligament-like, and bone-like tissues. No normal pulp and nerve tissue were observed. CONCLUSION: Both PRP and MTA may be ideal scaffolds to accelerate the regeneration process. CLINICAL SIGNIFICANCE: Pulp repair in immature permanent teeth with weak roots has a better outcome than replacement of the pulp with gutta-percha or biomaterials.

Age estimation based on pulp cavity/chamber volume of 13 types of tooth from cone beam computed tomography images.

AIM: The aims of this study are to identify which type of tooth has the strong relationship between age and pulp cavity/chamber volume among 13 types of tooth from the same dentition and to determine whether the inclusion of multiple types of tooth may improve the accuracy of age estimation. MATERIALS AND METHODS: Cone beam computed tomography (CBCT) images from 115 females and 125 males aged between 16 and 63 years were analyzed. The DICOM data of all the images were imported into ITK-SNAP 2.4 for the calculation of pulp cavity/chamber volumes. Logarithmic regression analysis and multiple linear regression analysis were applied to establish the relationship between age and pulp cavity/chamber volumes. RESULTS: Among the 13 types of tooth, maxillary second molars have the largest R (2) (0.491, 0.642, and 0.498) and the smallest SEE (8.119, 6.754, and 8.022) in male, female, and pooled gender samples, respectively. The multiple linear regression analysis for the combination of multi-types of tooth indicated that a larger R (2) (0.627, 0.701, and 0.631) and smaller SEE (7.100, 6.258, and 6.970) than the counterpart calculated from the logarithmic regression analysis of a single type of tooth in male, female, and pooled gender samples, respectively. CONCLUSION: The pulp chamber volume of the maxillary second molars has the largest correlation coefficient with age. Using multiple types of tooth may improve the accuracy of age estimation compared with only one type of tooth used.

Maximum likelihood estimate of life expectancy in the prehistoric Jomon: Canine pulp volume reduction suggests a longer life expectancy than previously thought.

Recent theoretical progress potentially refutes past claims that paleodemographic estimations are flawed by statistical problems, including age mimicry and sample bias due to differential preservation. The life expectancy at age 15 of the Jomon period prehistoric populace in Japan was initially estimated to have been ∼16 years while a more recent analysis suggested 31.5 years. In this study, we provide alternative results based on a new methodology. The material comprises 234 mandibular canines from Jomon period skeletal remains and a reference sample of 363 mandibular canines of recent-modern Japanese. Dental pulp reduction is used as the age-indicator, which because of tooth durability is presumed to minimize the effect of differential preservation. Maximum likelihood estimation, which theoretically avoids age mimicry, was applied. Our methods also adjusted for the known pulp volume reduction rate among recent-modern Japanese to provide a better fit for observations in the Jomon period sample. Without adjustment for the known rate in pulp volume reduction, estimates of Jomon life expectancy at age 15 were dubiously long. However, when the rate was adjusted, the estimate results in a value that falls within the range of modern hunter-gatherers, with significantly better fit to the observations. The rate-adjusted result of 32.2 years more likely represents the true life expectancy of the Jomon people at age 15, than the result without adjustment. Considering ∼7% rate of antemortem loss of the mandibular canine observed in our Jomon period sample, actual life expectancy at age 15 may have been as high as ∼35.3 years.

Use of the Tooth Coronal Pulp Index for Recognition of the Pubertal Growth Period.

AIM: The present study aimed to investigate the association between the tooth coronal index (TCI) and the pubertal growth stages (PGS) for children and adolescents. MATERIALS AND METHODS: A cross-sectional study was performed using retrospectively collected panoramic and hand-wrist radiographs of 262 individuals (125 males, 137 females). The coronal height (CH) and the coronal pulp cavity height (CPCH) of the left mandibular teeth were measured. Then the TCI for which was calculated according to Ikeda et al (1985). The estimated TCI for individuals with the following PGS after Fishman (1987) are: SMI 4 (S), SMI 5 (DP3 cap), SMI 6 (MP3 cap) and SMI 7 (Mp5 cap). The associations between the TCI and the PGS were investigated by correlation coefficient of Spearman's rho, and the validity values for the PGS were computed. RESULTS: Significant correlations were noted between the simple TCI values for premolars and molars and the PGS, and the highest correlation was for the summed TCI for both first and second molars. Utilizing the validity values of the summed TCI for both first and second mandibular molars, the PGS can be predicted as follows: S stage when TCI is 49.17 or lesser, DP3cap stage when TCI is 43.52 or lesser, MP3cap stage when TCI is 36.73 or lesser, and Mp5cap stage when TCI is 26.84 or lesser. CONCLUSION: The TCI values declined along with the maturational process in children and adolescents. The TCI for both first and second molars was the best predictor of the PGS. CLINICAL SIGNIFICANCE: Panoramic photographs can be beneficial for prediction of the skeletal maturity and treatment planning without resorting to hand-wrist radiographs.

Dental Age Estimation Helps Create a New Identity.

Age estimation involves the reconstruction of age by biological parameters such as skeletal and dental development in minors, or reduction of pulp chamber in adults, to gain indications concerning the chronological age of the person. In most cases, it is needed in forensic scenarios to verify if the supposed age of an individual is correct; in exceptional cases, age estimation is instead required by judicial authorities to create a new identity usually in persons who do not remember who they are.This article aims at reporting the case of J. who was found in 2005 with signs of amnesia because he did not remember his name and age. After several unsuccessful attempts at identifying him, the judicial authority decided to assign a new identity, which was to be constructed according to the real biological data of the individual. The help of a forensic pathologist and a forensic odontologist was then requested, and age estimation was reached by applying methods for adults based on the physiological reduction of pulp chamber. Dental age estimation yielded a final result of approximately 31 years, which was the new age assigned to the person.This article shows a peculiar application of dental age estimation, which can be used not only to ascertain or deny supposed age, but is sometimes needed to create a new identity.

Diffusion of HEMA from resin cements through different dentin thicknesses in vitro.

PURPOSE: To evaluate the in vitro diffusion of 2-hydroxyethyl methacrylate (HEMA) from the resin cements through different thicknesses of dentin using high-performance liquid chromatography (HPLC) at two time intervals. METHODS: 60 freshly extracted caries- and restoration-free human third molar teeth were used in this study. Standardized box-shaped Class I inlay cavities (6 mm long, 3 mm wide and 2 mm deep) were prepared in all teeth with a high-speed handpiece mounted on a standard cavity machine. The remaining dentin thickness (RDT) between the pulpal wall of the cavity and the roof of the pulp chamber was measured at multiple points for each tooth so that two main groups of 30 teeth each were prepared with an RDT range 0.5-1.9 and 2.0-3.5 mm, respectively. Each of these main groups was divided into three subgroups (n = 10), according to the resin cements tested (RelyX ARC, Panavia F 2.0, Multilink Automix). Lithium disilicate-based ceramic inlays (IPS Empress 2) were manufactured to restore the prepared cavities. A polypropylene chamber containing 1 ml distilled water was attached to the cemento-enamel junction of each tooth. Then, ceramic inlays were cemented with resin cements according to the manufacturers' instructions. Water elutes were analyzed by HPLC at 4.32 minutes and 24 hours. HEMA diffusion amounts were analyzed using three-way ANOVA and Tukey's HSD tests (P < 0.05). RESULTS: HEMA was detected in the pulp chamber elutes of all the teeth. The amounts of released HEMA did not significantly differ between time periods. The diffused HEMA amounts were significantly different between the RDT of 0.5-1.9 and 2.0-3.5 mm (P < 0.05) and between resin cements tested (P < 0.05). Decreasing RDT substantially increased the amount of HEMA that diffused through the dentin to the pulp space.

Infected Dentine Revisited.

Dentine becomes infected as a result of caries lesion formation on root surfaces and when lesions progress following cavitation of enamel lesions. However, this infection is unimportant because the driving force for lesion formation and progression is the overlying biofilm. This explains why root surface caries can be controlled by mechanical plaque control and fluoride, and restorations are not needed to arrest these lesions. Similarly, the infected dentine in cavitated coronal lesions does not have to be removed to arrest the lesion. If the lesion is either accessible or opened for cleaning by the patient or parent, the lesion can be arrested. Sealing of infected dentine within the tooth, either by a Hall crown in the primary dentition or by partial caries removal prior to placing a well-sealed filling, will also arrest the lesion. When restoring deep lesions in symptomless, vital teeth, vigorous excavation of infected dentine is likely to expose the pulp and make root canal treatment necessary. Thus complete excavation'is not needed and should be avoided. CPD/CLINICAL RELEVANCE: Root surface caries can be arrested by cleaning and fluoride application. Restorations are not essential. Vigorous excavation of softened dentine in deep cavities of symptomless, vital teeth is contra-indicated. It is not needed and increases the risk of pulp exposure.

Finite element analysis of stress distribution in ceramic crowns fabricated with different tooth preparation designs.

STATEMENT OF PROBLEM: Information about the effect of occlusal preparation designs on the stress distribution in different ceramic crowns and the prepared tooth is limited. PURPOSE: The purpose of this study was to investigate the effects of anatomic and nonanatomic occlusal preparation designs on the stress distribution in ceramic crowns, teeth, and bone. MATERIAL AND METHODS: Finite element analysis was performed on models of a mandibular second premolar. A load of 400 N was applied to the models to test ceramic materials (In-Ceram, Empress Esthetic) and occlusal preparation (anatomic, nonanatomic) designs. RESULTS: The lowest stress value occurred in the core material in the Empress Esthetic model prepared with the nonanatomic occlusal preparation design. In all groups, higher stress values were found to be concentrated in the lingual half of the dentin. Lower stress values were located near the apex of the pulp tissue and bony tissue that surround the root apex. CONCLUSIONS: Differences in preparation designs did not result in differences in the distribution or amount of stress in pulp, dentin, or bone. The use of different ceramic materials resulted in no differences in the amount or distribution of stress in pulp and bone. The use of a crown with a high elastic modulus led to increases in stress values in the restoration and the dentin margin, and decreases in stress values in the occlusal surface of the dentin. The nonanatomic design can be recommended as a favorable preparation design for Empress Esthetic ceramic.

Micro-CT analyses of apical enlargement and molar root canal complexity.

AIM: To compare the effectiveness of two rotary hybrid instrumentation techniques with focus on apical enlargement in molar teeth and to quantify and visualize spatial details of instrumentation efficacy in root canals of different complexity. METHODOLOGY: Maxillary and mandibular molar teeth were scanned using X-ray microcomputed tomography. Root canals were prepared using either a GT/Profile protocol or a RaCe/NiTi protocol. Variables used for evaluation were the following: distance between root canal surfaces before and after preparation (distance after preparation, DAP), percentage of root canal area remaining unprepared and increase in canal volume after preparation. Root canals were classified according to size and complexity, and consequences of unprepared portions of narrow root canals and intraradicular connections/isthmuses were included in the analyses. One- and two-way anova were used in the statistical analyses. RESULTS: No difference was found between the two techniques: DAP(apical-third) (P = 0.590), area unprepared(apical-third) (P = 0.126) and volume increase(apical-third) (P = 0.821). Unprepared root canal area became larger in relation to root canal size and complexity, irrespective of the technique used. Percentage of root canal area remaining unprepared was significantly lower in small root canals and complex systems compared to large root canals. The isthmus area per se contributed with a mean of 17.6%, and with a mean of 25.7%, when a narrow root canal remained unprepared. CONCLUSIONS: The addition of isthmuses did not significantly alter the ratio of instrumented to unprepared areas at total root canal level. Distal and palatal root canals had the highest level of unprepared area irrespective of the two instrumentation techniques examined.

Three-dimensional ultrashort echo magnetic resonance imaging of orthodontic appliances in the natural dentition.

INTRODUCTION: The purpose of this study was to determine whether ultrashort echo time magnetic resonance imaging technology could be used to image teeth with orthodontic appliances in place. METHODS: High-resolution 3-T ultrashort echo time magnetic resonance imaging was performed on 60 extracted premolars with fixed ceramic orthodontic appliances (Clarity, 3M Unitek, Monrovia, Calif; Radiance, American Orthodontics, Sheboygan, Wis; and Ice, Ormco, Glendora, Calif). The teeth were collected from the orthodontic clinic at the University of Alabama at Birmingham, and the institutional review board of the University of Alabama at Birmingham approved the study. Linear measurements of tooth morphology and orthodontic bracket dimensions were acquired with calipers and compared with virtual digital magnetic resonance imaging. The spin echo and high spatial resolution multi-slice turbo spin echo were only used for visual comparison with the ultrashort echo time slices. Both the caliper and the ultrashort echo time magnetic resonance imaging measurements were highly reliable and accurate. Comparisons between the 2 methods showed no statistically significant differences in any bracket or tooth dimensions, with a P value of >0.05. In general, the differences in the values ranged from -0.01 to 0.06 mm. A visual evaluation scale was used to assess the quality of the ultrashort echo time magnetic resonance images when assessing the delineation of dental hard tissues. RESULTS: The visual evaluation scale of the images showed that enamel, dentin, pulp, and ceramic orthodontic appliances could be subjectively delineated at a high level with the ultrashort echo time magnetic resonance imaging. CONCLUSIONS: The following conclusions can be drawn from this prospective study. Ceramic orthodontic appliances, without metal components, cause no dental image distortions and are readily visible on the ultrashort echo time magnetic resonance imaging scans. The measurements comparing linear tooth measurements with virtual digital magnetic resonance images demonstrated that magnetic resonance imaging has statistically and clinically significant accuracy on external tooth and bracket measurements. Visual evaluation of the images showed that enamel, dentin, pulp, and ceramic orthodontic appliances could be subjectively delineated at a high level with ultrashort echo time magnetic resonance imaging. Metallic slots in ceramic appliances cause severe image distortions. These distortions are localized and should not affect surrounding tissues in full-volume magnetic resonance imaging.

A histological study of pulp reaction to various water/powder ratios of white mineral trioxide aggregate as pulp-capping material in human teeth: a double-blinded, randomized controlled trial.

AIM: To compare the histological pulp reaction to various water/powder ratios of white mineral trioxide aggregate (MTA) as a pulp-capping material in healthy human teeth. METHODOLOGY: Twenty-nine disease-free maxillary and mandibular third molar teeth, scheduled for extraction, were exposed mechanically and then capped with 0.28, 0.33 and 0.40 water/powder ratios of white MTA (ProRoot; Dentsply Maillefer, Ballaigues, Switzerland) and restored with glass ionomer. After 30 days, the teeth were extracted, resected apically and immersed in 10% formalin. For histological processing, the teeth were sectioned buccolingually in 5-µm-thick slices, stained with Haematoxylin and Eosin and evaluated by a light microscope. Samples were evaluated for intensity and type of inflammation, presence of necrosis, as well as continuity, morphology and thickness of calcified bridges. The data were analysed by Kruskal-Wallis and Mann-Whitney tests. RESULTS: There were no significant differences in the diameter, morphology and continuity of the calcified bridges, intensity and type of inflammation or presence of necrosis (P > 0.05) in the pulps covered by MTA with various water/powder ratios. Two teeth failed to display a calcified bridge, and one had a pulp necrosis. CONCLUSION: Water-to-powder ratios of MTA had no significant influence on the histological outcome of direct pulp capping on healthy pulps.

Root and canal morphology of Indian maxillary premolars by a modified root canal staining technique.

The aim of this study was to investigate the root and canal morphology of maxillary first and second premolars in Indians by a modified canal staining and tooth clearing technique. Maxillary first (350) and second (350) premolars were collected, and the morphology and number of roots analyzed. After cleaning, the teeth were immersed in India ink and placed in a hyperbaric oxygen chamber at 0.6 MPa for 2 h. The teeth were then demineralized and cleared. Digital images of the teeth were examined under magnification to evaluate the number of root canals, root canal system configurations, number of apical foramina, and intercanal communications. Root canal configurations were identified based on Vertucci's classification and Gulabivala's additional classes. The most common root morphology of the first premolars was the classical two separate root morphology (a Caucasian trait) and that of the second premolars was a single-root morphology (a Mongoloid trait), though other morphologies such as singlerooted first premolars and three-rooted first and second premolars were also identified. A "radiculous" first premolar was identified in two samples. The buccal roots of the first premolar showed the maximum variation, the most common being type I (Vertucci's classification), followed by type IV. The highest incidence of intercanal communications was found in the single-rooted first premolars. All roots exhibiting type IV and V canal configurations showed two separate apical foramina, while additional type 2-3 canal configurations showed three separate apical foramina. The root number and morphology as well as the canal morphology of Indian maxillary premolars showed both Mongolian and Caucasian traits.

Endodontic diagnostic terminology update.

Determination of the etiology of the patient's chief complaint and a correct diagnosis are paramount prior to a recommendation of endodontic therapy. Reproduction of the patient's chief complaint is critical. If the chief complaint cannot be reproduced, consider consultation with or referral to an endodontist or orofacial pain specialist. The diagnostic terminology presented in this update provides for a more accurate description and communication of the health or pathological conditions of both pulpal and apical tissues. This information is summarized in Table I.

Sex classification of first molar teeth in cone beam computed tomography images using data mining.

OBJECTIVE: The teeth have been used as a supplementary tool for sex differentiation as they are resistant to post-mortem degradation. The present study aimed to develop a new novel informatics framework for predicting sex from linear tooth dimension measurements achieved from cone beam computed tomography (CBCT) images. METHOD AND MATERIALS: A clinical workflow using different machine learning methods was employed to predict the sex in the present study. The CBCT images of 485 subjects (245 men and 240 women) were evaluated for sex differentiation. Nine parameters were measured in both buccolingual and mesiodistal aspects of the teeth. We applied our dataset to Naïve Bayesian (NB), Random Forest (RF), and Support Vector Machine (SVM) as classifiers for prediction. Genetic feature selection was used to discover real features associated with sex classification. RESULTS: The 10-fold cross-validation results indicated that NB had higher accuracy than SVM and RF for sex classification. The genetic algorithm (GA) indicated that the model could fit the data without using the enamel thickness and pulp height. The average classification accuracy of our clinical workflow was 92.31 %. CONCLUSION: The results showed that NB was the best method for sex classification. The application of the first molar teeth in sex prediction indicated an acceptable level of sexual classification. Therefore, these odontometric parameters can be applied as an additional tool for sex determination in forensic anthropology.

Absence of lymphatic vessels in the dog dental pulp: an immunohistochemical study.

In spite of numerous investigations it has not been precisely determined whether lymphatic vessels are present in the dental pulp of dogs. Therefore, this study attempted a specific immunohistochemical detection of lymphatic endothelium. The canine teeth of 19 healthy beagle dogs were dissected into three segments (apical, intermediate and occlusal). After decalcification, specimens were embedded in paraffin wax and histologic cross-sections were stained immunohistochemically using a reliable antibody (anti-Prox-1) against the homeobox transcription factor Prox-1, which is located within the nucleus of lymphatic endothelium. Anti-Prox-1 reacted positively with canine control tissues (lymph nodes, gingiva, nasal mucosa), but showed no staining in tissue sections of the dental pulp. The dog dental pulp contained no vascular structures lined with lymphatic endothelium. This suggests that drainage of interstitial fluid makes use of other routes, i.e. extravascular pathways.

Mandibular molar root morphology in Neanderthals and Late Pleistocene and recent Homo sapiens.

Neanderthals have a distinctive suite of dental features, including large anterior crown and root dimensions and molars with enlarged pulp cavities. Yet, there is little known about variation in molar root morphology in Neanderthals and other recent and fossil members of Homo. Here, we provide the first comprehensive metric analysis of permanent mandibular molar root morphology in Middle and Late Pleistocene Homo neanderthalensis, and Late Pleistocene (Aterian) and recent Homo sapiens. We specifically address the question of whether root form can be used to distinguish between these groups and assess whether any variation in root form can be related to differences in tooth function. We apply a microtomographic imaging approach to visualise and quantify the external and internal dental morphologies of both isolated molars and molars embedded in the mandible (n=127). Univariate and multivariate analyses reveal both similarities (root length and pulp volume) and differences (occurrence of pyramidal roots and dental tissue volume proportion) in molar root morphology among penecontemporaneous Neanderthals and Aterian H. sapiens. In contrast, the molars of recent H. sapiens are markedly smaller than both Pleistocene H. sapiens and Neanderthals, but share with the former the dentine volume reduction and a smaller root-to-crown volume compared with Neanderthals. Furthermore, we found the first molar to have the largest average root surface area in recent H. sapiens and Neanderthals, although in the latter the difference between M(1) and M(2) is small. In contrast, Aterian H. sapiens root surface areas peak at M(2). Since root surface area is linked to masticatory function, this suggests a distinct occlusal loading regime in Neanderthals compared with both recent and Pleistocene H. sapiens.

Absence of lymphatic vessels in human dental pulp: a morphological study.

Few and controversial data are available in the literature regarding the presence of lymphatic vessels in the human dental pulp. The present study was designed to examine morphologically the existence of a lymph drainage system in human dental pulp. Human dental pulp and skin sections were immunohistochemically stained with specific antibodies for lymphatic endothelium (D2-40, LYVE-1, VEGFR-3 [vascular endothelial growth factor receptor-3], and Prox-1), with the pan-endothelial markers CD31 and von Willebrand factor (vWF), and with the blood-specific marker CD34. Several blood vessels were identified in human pulps and skin. Lymphatic vessels were found in all human skin samples but in none of the pulps examined. Western blotting performed on human dermis and on pulps treated with collagenase (to remove odontoblasts) confirmed these results. Transmission electron microscopy indicated that vessels which, by light microscopy, appeared to be initial lymphatic vessels had no anchoring filaments or discontinuous basement membrane, both of which are typical ultrastructural characteristics of lymphatic vessels. These results suggest that under normal conditions human dental pulp does not contain true lymphatic vessels. The various theories about dental pulp interstitial fluid circulation should be revised accordingly.