Root Surfaces Of Teeth Research Articles

Tooth periodontal ligament: Direct 3D microCT visualization of the collagen network and how the network changes when the tooth is loaded

The periodontal ligament (PDL), a soft tissue connecting the tooth and the bone, is essential for tooth movement, bone remodeling and force dissipation. A collagenous network that connects the tooth root surface to the alveolar jaw bone is one of the major components of the PDL. The organization of the collagenous component and how it changes under load is still poorly understood. Here using a state-of-the-art custom-made loading apparatus and a humidified environment inside a microCT, we visualize the PDL collagenous network of a fresh rat molar in 3D at 1 μm voxel size without any fixation or contrasting agents. We demonstrate that the PDL collagen network is organized in sheets. The spaces between sheets vary thus creating dense and sparse networks. Upon vertical loading, the sheets in both networks are stretched into well aligned arrays. The sparse network is located mainly in areas which undergo compressive loading as the tooth moves towards the bone, whereas the dense network functions mostly in tension as the tooth moves further from the bone. This new visualization method can be used to study other non-mineralized or partially mineralized tissues, and in particular those that are subjected to mechanical loads. The method will also be valuable for characterizing diseased tissues, as well as better understanding the phenotypic expressions of genetic mutants.

Immunolocalization of RANK and RANKL along the root surface and in the periodontal membrane of human primary and permanent teeth

Objective. Root resorption, impaired tooth eruption and early tooth loss have been described in relation to diseases that involve defects in the RANK-RANKL-OPG-expression. The aim of the present immunhistochemical study was to localize and compare the reactions for RANK and membrane-bound RANKL along root surfaces and in the periodontal membrane in close proximity to the root surface of human primary and permanent teeth. Materials and methods. The material comprised extracted human teeth (11 primary teeth and six permanent teeth) from 10 different patients. Paraffin sections were prepared of each tooth and sections of each tooth were immunohistochemically stained with antibodies specific for membrane-bound RANKL and RANK. Results. The root surface and the periodontal membrane in close proximity to the root surface did not show immunoreactivity for RANKL. RANKL was only located in odontoblasts and in cells along denticles in one primary tooth. RANK was located in mononuclear cells in the pulp and in multinucleated odontoclasts along resorbed root surfaces and along resorbed dentin surfaces in the pulp in primary teeth and one permanent tooth. Conclusions. This study demonstrated RANK positivity in resorption areas in primary and permanent teeth. RANKL was positive in the pulp of one primary tooth. RANK expression in odontoclasts and RANKL expression in the pulp may indicate that RANK/RANKL play a role during resorption.

Local Residual Stress Distribution at the Tooth Root Surface of a Broached Steel Component

Broaching is an important technique for creating tooth structures in mechanical components. In the present work, the effects of the broaching process on the material state in the near surface region at the root of the tooth was analyzed. The studies were carried out on broached plates made from case hardening steel SAE 5120. The cutting speed and machining condition (cooling lubricant, dry machining) were varied. During broaching with a TiAlN coated tool the cutting forces were monitored. Subsequently, the local residual stresses at the root of the tooth were determined using X-ray diffraction. Further, surface roughness and micro hardness measurements as well as microstructure analysis complement the results. The results indicate that cutting forces have a high influence on the development of the residual stress state at the machined surface whereas no significant effect on changes in surface hardness and microstructure could be observed. Dry cutting with relatively high cutting speeds (≥ 30m/min) result in low cutting forces and hence in high tensile residual stresses in broaching direction.

Comparison of the efficacy of ethylenediaminetetraacetic acid and tetracycline hydrochloride as root conditioning agents: An in vitro study

Objective: Root surfaces of periodontitis-affected teeth are hypermineralized and contaminated with cytotoxic and other biologically active substances. Various root conditioning agents have been recommended as an adjunct to mechanical root surface debridement to expose dentin collagen and cementum bound proteins. The aim of the present in vitro study was to compare the efficacy of ethylenediaminetetraacetic acid (EDTA) and tetracycline hydrochloride (HCl) as root conditioning agents on planed root surfaces. Materials and Methods: A total of 20 human maxillary anterior teeth indicated for extraction due to chronic periodontitis were collected and root planed. The teeth were sectioned and specimens were divided into two groups - Group I and II. Group I dentin specimens were treated with EDTA and Group II specimens were treated with tetracycline HCl solution at a concentration of 10% by active burnishing technique for 3 min. The root surface samples were then examined by scanning electron microscope. Results: The results of this study showed that EDTA and tetracycline HCl were equally effective in removing the smear layer. It was observed that the total and patent dentinal tubules were more in number in teeth treated with tetracycline when compared to EDTA group. However, EDTA was found to be much more effective as root conditioning agent because it enlarged the diameter of dentinal tubules more than that of tetracycline HCl. Conclusion: The results of in vitro study showed that both the agents are good root conditioning agents if applied in addition to periodontal therapy. However, further studies are required to establish the in vivo importance of EDTA and tetracycline HCL as root conditioners.

Minimizing the extra-oral time in autogeneous tooth transplantation: use of computer-aided rapid prototyping (CARP) as a duplicate model tooth

ObjectivesThe maintenance of the healthy periodontal ligament cells of the root surface of donor tooth and intimate surface contact between the donor tooth and the recipient bone are the key factors for successful tooth transplantation. In order to achieve these purposes, a duplicated donor tooth model can be utilized to reduce the extra-oral time using the computer-aided rapid prototyping (CARP) technique.Materials and MethodsBriefly, a three-dimensional digital imaging and communication in medicine (DICOM) image with the real dimensions of the donor tooth was obtained from a computed tomography (CT), and a life-sized resin tooth model was fabricated. Dimensional errors between real tooth, 3D CT image model and CARP model were calculated. And extra-oral time was recorded during the autotransplantation of the teeth.ResultsThe average extra-oral time was 7 min 25 sec with the range of immediate to 25 min in cases which extra-oral root canal treatments were not performed while it was 9 min 15 sec when extra-oral root canal treatments were performed. The average radiographic distance between the root surface and the alveolar bone was 1.17 mm and 1.35 mm at mesial cervix and apex; they were 0.98 mm and 1.26 mm at the distal cervix and apex. When the dimensional errors between real tooth, 3D CT image model and CARP model were measured in cadavers, the average of absolute error was 0.291 mm between real teeth and CARP model.ConclusionsThese data indicate that CARP may be of value in minimizing the extra-oral time and the gap between the donor tooth and the recipient alveolar bone in tooth transplantation.

Cementum protein 1 (CEMP1) induces a cementoblastic phenotype and reduces osteoblastic differentiation in periodontal ligament cells

Cementum is a calcified tissue covering the tooth root surface, which functions as rigid tooth-anchoring structure. Periodontal ligament is a unique non-mineralized connective tissue, and is a source of mineralized tissue forming cells such as cementoblasts and osteoblasts. The CEMP1 is a novel cementum component the presence of which appears to be limited to cementoblasts and their progenitors. In order to understand the function of CEMP1, we investigated CEMP1 expression during the differentiation of human periodontal ligament cells. Immunomagnetically enriched alkaline phosphatase (ALP)-positive periodontal ligament cells preferentially expressed CEMP1. CEMP1 expression was reduced when periodontal ligament cells differentiated to osteoblasts in vitro. Over-expression of CEMP1 in periodontal ligament cells enhanced cementoblast differentiation and attenuated periodontal and osteoblastic phenotypes. Our data demonstrate for the first time that the CEMP1 is not only a marker protein for cementoblast-related cells, but it also regulates cementoblast commitment in periodontal ligament cells.

Tooth root morphology as an indicator for dietary specialization in carnivores (Mammalia: Carnivora)

The Carnivora occupy a wide range of feeding niches in concordance with the enormous diversity in their skull and dental form. It is well established that differences in crown morphology are linked to variations in the material properties of the foods ingested and masticated. However, how tooth root form is related to dietary specialization is less well known. In the present study, we investigate the relationship between tooth root morphology and dietary specialization in terrestrial carnivores (canids, felids, hyaenids, and ursids). We specifically address the question of how variation in tooth root surface area is related to bite force potentials as one of the crucial masticatory performance parameters in feeding ecology. We applied computed tomography imaging to reconstruct and quantify dental root surface area in 17 extant carnivore species. Moreover, we computed maximal bite force at several tooth positions based on a dry skull model and assessed the relationship of root surface area to skull size, maximal bite force, food properties, and prey size. We found that postcanine tooth root surface areas corrected for skull size serve as a proxy for bite force potentials and, by extension, dietary specialization in carnivores. Irrespective of taxonomic affinity, species that feed on hard food objects have larger tooth roots than those that eat soft or tough foods. Moreover, carnivores that prey on large animals have larger tooth root surface areas. Our results show that tooth root morphology is a useful indicator of bite force production and allows inferences to be made about dietary ecology in both extant and extinct mammals.

The inter-relation between epithelial cells of Malassez and vessels studied immunohistochemically in the periodontal membrane of human primary and permanent teeth

Background. Only few immunohistochemical studies have focused on the periodontal membrane in human primary teeth. Recently, studies on epithelial cells of Malassez and innervation have been published. Studies on the inter-relation between vessels and the epithelial cells of Malassez are seemingly lacking. Aim. The aim of this immunohistochemical study is to describe the histological inter-relation between epithelial cells of Malassez and vessels in the periodontal membrane close to the root surface of human primary and permanent teeth. Methods. Twenty-nine human primary teeth and 15 permanent teeth were extracted in connection with dental treatment. The teeth were fixated, embedded in paraffin, cut in serial sections and examined immunohistochemically for epithelial cells of Malassez using wide spectrum screening and vessels using Von Willebrand Factor VIII. Results. The study showed that vessels and epithelial cells of Malassez are seen parallel to the root surface. The vessels are seen on that side of the epithelial cells of Malassez, which are not facing the root surface. Conclusion. The vascularization appeared similar in primary and permanent teeth.

Harvesting cementum from root surface: A new paradigm in the study of cementum and the cemento-dentinal junction

Cementum and the cemento-dentinal junction has been a subject of debate for long. Here, the author has demonstrated an unreported technique to harvest cementum from the surface of the root surface of human teeth and also reviewed literature with respect to the cemento-dentinal junction. The method was based on the conclusion that the tissue between radicular dentin and cementum is an enamel-like hypermineralized tissue. The demineralization protocol reported demineralises the hypermineralized intermediate tissue and this dissolution unlocks the junction releasing the cementum from the radicular dentin surface. The cementum is separated as sock or in shreds and the observations reported.

The functional morphology of the anterior masticatory apparatus in tree‐gouging marmosets (cebidae, primates)

Although all genera of Callitrichinae feed on tree exudates, marmosets (Callithrix and Cebuella) use specialized anterior teeth to gouge holes in trees and actively stimulate exudate flow. Behavioral studies demonstrate that marmosets use large jaw gapes but do not appear to generate large bite forces (relative to maximal ability) during gouging. Nonetheless, the anterior teeth of marmosets likely experience different loads during gouging compared to nongouging platyrrhines. We use histological data from sectioned teeth, μCTs of jaws and teeth, and in vitro tests of symphyseal strength to compare the anterior masticatory apparatus in Callithrix to nongouging tamarins (Saguinus) and other cebids. We test the hypotheses that (1) marmoset anterior teeth are adapted to accommodate relatively high stresses linked to dissipating gouging forces and (2) the mandibular symphysis does not provide increased load resistance ability compared with closely related nongouging platyrrhines. Differences in decussation between Callithrix and Saguinus are greatest in the anterior teeth, suggesting an increased load resistance ability specifically in incisor and canine enamel of Callithrix. Callithrix lower incisor crowns are labiolingually thicker suggesting increased bending resistance in this plane and improved wedging ability compared with Saguinus. Anterior tooth roots are larger relative to symphyseal bone volume in Callithrix. Anterior tooth root surface areas also are larger in marmosets for their symphyseal volume, but it remains unclear whether this relative increase is an adaptation for dissipating dental stresses versus a growth-related byproduct of relatively elongated incisors. Finally, simulated jaw loading suggests a reduced ability to withstand external forces in the Callithrix symphysis. The contrast between increased load resistance ability in the anterior dentition versus relatively reduced symphyseal strength (1) suggests a complex loading environment during gouging, (2) highlights the possibility of distinct loading patterns in the anterior teeth versus the symphysis, and (3) points to a potential mosaic pattern of dentofacial adaptations to tree gouging.

Successful Periodontal Ligament Regeneration by Periodontal Progenitor Preseeding on Natural Tooth Root Surfaces

The regeneration of lost periodontal ligament (PDL) and alveolar bone is the purpose of periodontal tissue engineering. The goal of the present study was to assess the suitability of 3 odontogenic progenitor populations from dental pulp, PDL, and dental follicle for periodontal regeneration when exposed to natural and synthetic apatite surface topographies. We demonstrated that PDL progenitors featured higher levels of periostin and scleraxis expression, increased adipogenic and osteogenic differentiation potential, and pronounced elongated cell shapes on barren root chips when compared with dental pulp and dental follicle cells. When evaluating the effect of surface characteristics on PDL progenitors, natural root surfaces resulted in elongated PDL cell shapes, whereas PDL progenitors on synthetic apatite surfaces were rounded or polygonal. In addition, surface coatings affected PDL progenitor gene expression profiles: collagen I coatings enhanced alkaline phosphatase and osteocalcin expression levels and laminin-1 coatings increased epidermal growth factor (EGF), nestin, cadherin 1, and keratin 8 expression. PDL progenitors seeded on natural tooth root surfaces in organ culture formed new periodontal fibers after 3 weeks of culture. Finally, replantation of PDL progenitor-seeded tooth roots into rat alveolar bone sockets resulted in the complete formation of a new PDL and stable reattachment of teeth over a 6-month period. Together, these findings indicate that periodontal progenitor cell type as well as mineral surface topography and molecular environment play crucial roles in the regeneration of true periodontal anchorage.

Monocortical Mandibular Bone Grafting for Reconstruction of Alveolar Cleft

To assess and develop a monocortical mandibular bone grafting procedure for reconstruction of alveolar cleft. Prospective study. Hokkaido University Hospital. Forty-two consecutive Japanese patients who had been treated for a total of 48 clefts according to a strict clinical protocol. Mean age at bone grafting was 6 years 11 months. Bone grafting was performed by harvesting lateral cortical bone plates from the symphysis and/or body and then placing them on the labial and palatal openings of the alveolar process defect. No particulate bone grafts were packed into the bony cavity. Mean follow-up after bone grafting was 37 months. Status of the grafted area and eruption of cleft-adjacent teeth were assessed prospectively using computed tomography and periapical radiography. At 6 months postoperatively, computed tomography showed sufficient bone bridge formation at the cleft site in 85.4% of clefts. Periapical radiography showed ≥75% of the root surfaces of cleft-adjacent teeth were covered with spanning bone in 83.3% of clefts. In 92.6% of clefts in which the cleft-adjacent canine was uncovered with bone during follow-up, the canines erupted spontaneously. Monocortical mandibular bone grafting appears extremely effective for sufficient bone bridge formation and facilitation of cleft-adjacent teeth eruption. The procedure is advantageous in that the quantity of bone required per unit volume of cleft defect is relatively reduced, and larger clefts can thus be treated.

Tooth Root Size, Chewing Muscle Leverage, and the Biology ofHomunculus patagonicus(Primates) from the Late Early Miocene of Patagonia

Inferences about the diet of Miocene platyrrhine monkeys have relied upon the morphology of the molar teeth, specifically the crests on the molars. Using a library of Micro-CT images of a broad comparative sample of living platyrrhines (callitrichines, cebines, pitheciids and atelids), late early Miocene Homunculus, and the early Miocene Tremacebus and Dolichocebus, we extend these inferences by examining the surface areas of the tooth roots, anchor points for the periodontal ligaments. From muscle scars on the skull, we estimate the mechanical leverage of the chewing muscles at bite points from the canine to the last molar. Extant platyrrhines that gouge bark to obtain exudates do not have especially large canine roots or anterior premolar roots compared with their less specialized close relatives. Extant platyrrhines that have more folivorous diets have much larger molar roots than do similar-sized more frugivorous species. Homunculus patagonicus has large postcanine roots relative to body size and poor masticatory leverage compared to the extant platyrrhines in our sample. The large postcanine roots, heavy tooth wear, and moderately-long shearing crests suggests a diet of abrasive, resistant foods. However, relatively poor jaw adductor leverage would have put the masticatory apparatus of Homunculus at a mechanical disadvantage for producing high bite forces compared to the condition in extant platyrrhines. Tremacebus and Dolichocebus, like Homunculus, have larger tooth root surfaces than comparable-sized living platyrrhines. They also resemble Homunculus in being more prognathic and having posteriorly-located temporalis origins - all features of a relatively poor leverage system.

Dilated capillaries, disorganized collagen fibers and differential gene expression in periodontal ligaments of hypomorphic fibrillin-1 mice

The periodontal ligaments (PDLs) are soft connective tissue between the cementum covering the tooth root surface and alveolar bone. PDLs are composed of collagen and elastic system fibers, blood vessels, nerves, and various types of cells. Elastic system fibers are generally formed by elastin and microfibrils, but PDLs are mainly composed of the latter. Compared with the well-known function of collagen fibers to support teeth, little is known about the role of elastic system fibers in PDLs. To clarify their role, we examined PDLs of mice under-expressing fibrillin-1 (mgR mice), which is one of the major microfibrillar proteins. The PDLs of homozygous mgR mice showed one-quarter of the elastic system fibers of wild-type (WT) mice. A close association between the elastic system fibers and the capillaries was noted in WT, homozygous and heterozygous mgR mice. Interestingly, capillaries in PDLs of homozygous mice were dilated or enlarged compared with those of WT mice. A comparable level of type I collagen, which is the major collagen in PDLs, was expressed in PDL-cells of mice with three genotypes. However, multi-oriented collagen fiber bundles with a thinner appearance were noted in homozygous mice, whereas well-organized collagen fiber bundles were seen in WT mice. Moreover, there was a marked decrease in periostin expression, which is known to regulate the fibrillogenesis and crosslinking of collagen. These observations suggest that the microfibrillar protein, fibrillin-1, is indispensable for normal tissue architecture and gene expression of PDLs.

Formation of Caries-Like Lesions in vitro on the Root Surfaces of Human Teeth in Solutions Simulating Plaque Fluid

Lesion formation on root surfaces of human posterior teeth was studied in acetate/lactate buffers with a background electrolyte composition based on plaque fluid analyses. Lesion depth after 28 days at 37°C was measured in relation to: the presence or absence of cementum; the concentration of undissociated buffer; the presence or absence of magnesium ions at plaque fluid concentration. Each factor was evaluated at several values of –log(ion activity product for hydroxyapatite): pI_HA. Solutions were formulated to minimize variation in pH, which varied by ≤0.03 for a given comparison (individual pI_HA) and by 0.42–0.82 over the range of pI_HA within experiments. Lesions on surfaces from which cementum had been ground were significantly deeper than on intact surfaces, but this is considered to be due to subsurface mechanical damage and not to a solubility difference. Neither the concentration of undissociated buffer nor the presence of magnesium ions significantly affected lesion depth. Lesion depth was strongly influenced by the correlated variations in pI_HA and pH. At pI_HA 54 and 55, only extremely shallow lesions formed. From pI_HA 56, lesion depth increased with increasing pI_HA. The results confirm that the solubility of the mineral of root tissues is higher than that of hydroxyapatite, but indicate that it is probably lower than suggested by Hoppenbrouwers et al. [Arch Oral Biol 1987;32:319–322]. For calcium concentrations of 3–12 mM, the critical pH for root tissue mineral was calculated as 5.22–5.66 assuming solubility equivalent to pI_HA 54 and 5.08–5.51 assuming pI_HA 55.

Refractory apical periodontitis associated with a calculus-like deposit at the root apex

In this case report, we describe a refractory case in which a calculus-like deposit was found at the apical root surfaces of two adjacent teeth. This case involved a 45-year-old male with a sinus tract at the labial mucosa of the maxillary left central incisor, which did not heal after conventional root canal treatment of the maxillary left lateral incisor. Periradicular radiolucencies and unusual radio-opacities were noted on the root surfaces of the vital maxillary left central incisor and prior endodontically treated lateral incisor. Subsequent surgery found calculus-like particles at the root surface of both teeth. A pathology examination revealed calculus-like particles scattered in the granulomatous tissue. A test cavity confirmed pulp necrosis of the maxillary central incisor, and endodontic treatment was performed 1 year after surgery. At the 20-month recall, the size of the periapical radiolucency had decreased. The presence of calculus-like particles at the root surfaces was noted and may have possibly contributed towards the etiology of root canal treatment failure.

Influence of Water Cooling on Root Surface Temperature Generated During Post Space Preparation

IntroductionThis in vitro study evaluated the temperature increases on the root surface of teeth during preparation of post space with and without water cooling. MethodsThirty premolar teeth with a single canal were used. After root canal obturation, the teeth were divided into 2 groups, and post spaces were prepared by using a drill without cooling (dry group) and with water irrigation of 25 mL/min−1 (wet group). Temperatures were measured on the entire root surface by using a thermal imaging camera. ResultsRoot surface temperature increases were significantly lower when post spaces were created with water cooling compared with dry post preparation (P < .0001 for root canal filling removal and P < .0001 for post space preparation). In both groups, significantly higher temperatures were recorded during the post space preparation than during the filling removal (P < .001 for nonirrigated teeth and P < .001 for irrigated teeth). ConclusionsIrrigation during post space preparation significantly influenced the outer root surface temperature. The risk of irreversible injury to the root surrounding tissues is potentially minimized when post space is prepared by using water cooling.

下顎外側皮質骨を用いた顎裂部骨移植術の考案

A monocortical mandibular bone grafting procedure for reconstruction of alveolar cleft was developed and assessed prospectively. The procedure was performed by harvesting lateral cortical bone plates from the symphysis and/or mandibular body and then placing these plates on the labial and palatal openings of the alveolar process defect. No particulate bone grafts were packed into the bony cavity. Based on CT findings at 6 months postoperatively, 58 of 70 clefts (82.9 %), including immature bony bridge cases, showed sufficient bone formation at the cleft site in the labio-palatal direction to facilitate migration of the permanent canines and/or lateral incisors. From periapical radiographic findings at the time of last follow-up, 54 of 62 clefts (87.1 %), except nonclassified 8 clefts in which cleft-related teeth were erupting showed ≥ 75 ％ of the root surface of cleft-adjacent teeth was covered with spanning bone. In addition, canines had erupted spontaneously through grafted bone in occlusion for 27 of 29 clefts (93.1 %) in which the cleft-adjacent canine was uncovered with bone during follow-up. Packing of particulate bone grafts in a secondary bone grafting procedure is clearly not a prerequisite for sufficient bone bridge formation and facilitation of teeth eruption, and placement of walls of cortical bone to enclose the defect is adequate for successful secondary alveolar bone grafting in the mixed dentition. Our procedure has advantages in reducing the quantity of bone required per unit volume of cleft defect, and thus could be applicable to larger cleft defects.

Nance palatal arch: a cautionary tale

The Nance palatal arch is considered a useful means of maintaining arch length and reinforcing anchorage control in the orthodontic patient. Difficulty with oral hygiene around the Nance arch and inflammation and bunching of the gingivae under the acrylic fitting surface are common problems associated with this appliance. We present a case of alveolar bone loss and gingival recession around the palatal root surfaces of the upper incisor teeth following use of Nance palatal arch. A possible cause for this is explored and management of the patient after the Nance arch was removed is discussed.

SEM evaluation of the apical external root surface of teeth with chronic periapical lesion

The aim is to verify, under scanning electron microscopy, the occurrence of apical root resorption in anterior and posterior teeth with chronic and radiographically visible periapical lesions. Thirty-two teeth were extracted, the apical thirds (n = 39) were removed, and prepared to analyse the external apical root surface. All specimens presented irregular areas of root resorption with different depths, located mainly around the apical foramen. Teeth with chronic periapical lesions present areas of external apical root resorption with irregular surface and different depths located mainly around the apical foramen. Root resorptions may show different configurations and destroy the apical root structure more or less extensively.