Combined dental wear and cementum analyses in ungulates reveal the seasonality of Neanderthal occupations in Covalejos Cave (Northern Iberia).

We propose for the first time the use of the combination of two high-resolution techniques, dental wear (meso- and microwear) and dental cementum analyses, to gain a better understanding of Neanderthal subsistence strategies and occupational patterns. Dental wear analysis provides information not only on ungulate palaeodiet and palaeoenvironments but also on hunting time and seasons. Dental cementum analysis allows the accurate determination of the age and season at death of a prey. Our study has focused on the Cantabrian region and has applied both methods to investigate the Mousterian faunal assemblages in Covalejos Cave. Identification of the ungulate palaeodiet reveals information on the environmental conditions of the studied region. Moreover, it may facilitate observation on the evolution of both palaeodiet and palaeoenvironment throughout the site sequence. Results show a general stability in the palaeoenvironmental conditions and in the ungulate palaeodiet throughout the Mousterian sequence; this finding may be attributed to the role of the area as a climate refuge, and slight differences in levels 8, 7 and 4 suggest long- or short-term but repeated Neanderthal occupations at different seasons in the annual cycle.

Terapia endodóntica en pacientes adultos mayores ¿qué debemos tener en cuenta? / Endodontic therapy in elderly patients, what should we consider?

De acuerdo con la tendencia mundial, el número de personas de 60 años y más va en aumento. Este crecimiento demográfico de la población, el aumento de las expectativas de vida de las personas y la tendencia a la disminución de pacientes edéntulos, produce una mayor demanda de procedimientos endodónticos en la población anciana. Es fundamental que el odontólogo conozca la fisiología del envejecimiento para poder abordar, en forma eficaz, el tratamiento en los pacientes pertenecientes a este grupo etario. Se ha descripto que los tejidos dentales sufren cambios a lo largo de la vida; entre ellos, la reducción del número de fibroblastos, de odontoblastos, de vasos sanguíneos y de fibras nerviosas; el aumento de fibras colágenas, de masas calcificadas, aposición de cemento, de dentina secundaria y de dentina de reparación. El objetivo del presente trabajo es realizar una revisión bibliográfica en relación a los cambios que presentan la pulpa dental, la dentina y el cemento, relacionados con el proceso de envejecimiento y sus posibles dificultades al momento de realizar el tratamiento endodóntico; sin olvidar cómo pueden inferir en el éxito del tratamiento las posibles patologías sistémicas que presentan los pacientes a consecuencia de la edad (AU)

According to the world trend, the number of people aged 60 and over is increasing. This demographic growth of the population, the increase in people's life expectancies and the tendency to decrease edentulous patients, produces a greater demand for endodontic procedures in the elderly population. It is essential that the dentist knows the physiology of aging to be able to effectively address the treatment in patients belonging to this age group. It has been described that dental tissues suffer changes throughout life, including the reduction of the number of fibroblasts, odontoblasts, blood vessels and nerve fibers; the increase of collagen fibers, calcified masses, apposition of cement, secondary dentin and repair dentin. The objective of the present work is to carry out a bibliographic review in relation to the changes that the dental pulp, dentine and cement have in relation to the aging process and its possible consequences in the endodontic treatment; without forgetting how it can infer in the success of the treatment the possible systemic pathologies that patients present as a result of age (AU)

Physical properties of root cementum: Part 26. Effects of micro-osteoperforations on orthodontic root resorption: A microcomputed tomography study.

INTRODUCTION: Studies have demonstrated the potential efficacy of micro-osteoperforations in accelerating tooth movement by amplifying the expression of inflammatory markers. The aim of this investigation was to examine the effects of micro-osteoperforations on orthodontic root resorption with microcomputed tomography. METHODS: This prospective controlled clinical trial involved 20 subjects requiring extraction of the maxillary first premolars as part of their orthodontic treatment. A buccal tipping force of 150 g was applied to both premolars. Using the Propel appliance (Propel Orthodontics, San Jose, Calif), micro-osteoperforations were applied at a depth of 5 mm on the mesial and distal aspects in the midroot region of the experimental side of the first premolar root; the contralateral side served as the control. After 28 days, both premolars were extracted. The teeth were scanned under microcomputed tomography, and the volumes of root resorption craters were calculated and compared. RESULTS: Premolars treated with micro-osteoperforation exhibited significantly greater average total amounts of root resorption than did the control teeth (0.576 vs 0.406 mm3). The total average volumetric root loss of premolars treated with micro-osteoperforation was 42% greater than that of the control teeth. CONCLUSIONS: This 28-day trial showed that micro-osteoperforations resulted in greater orthodontic root resorption. However, these results should be verified in patients who are undergoing full-length orthodontic treatment.

Cellular and Molecular Pathways Leading to External Root Resorption.

External apical root resorption during orthodontic treatment implicates specific molecular pathways that orchestrate nonphysiologic cellular activation. To date, a substantial number of in vitro and in vivo molecular, genomic, and proteomic studies have supplied data that provide new insights into root resorption. Recent mechanisms and developments reviewed here include the role of the cellular component-specifically, the balance of CD68+, iNOS+ M1- and CD68+, CD163+ M2-like macrophages associated with root resorption and root surface repair processes linked to the expression of the M1-associated proinflammatory cytokine tumor necrosis factor, inducible nitric oxide synthase, the M1 activator interferon γ, the M2 activator interleukin 4, and M2-associated anti-inflammatory interleukin 10 and arginase I. Insights into the role of mesenchymal dental pulp cells in attenuating dentin resorption in homeostasis are also reviewed. Data on recently deciphered molecular pathways are reviewed at the level of (1) clastic cell adhesion in the external apical root resorption process and the specific role of α/ß integrins, osteopontin, and related extracellular matrix proteins; (2) clastic cell fusion and activation by the RANKL/RANK/OPG and ATP-P2RX7-IL1 pathways; and (3) regulatory mechanisms of root resorption repair by cementum at the proteomic and transcriptomic levels.

Cementum and Periodontal Ligament Regeneration.

The unique anatomy and composition of the periodontium make periodontal tissue healing and regeneration a complex process. Periodontal regeneration aims to recapitulate the crucial stages of wound healing associated with periodontal development in order to restore lost tissues to their original form and function and for regeneration to occur, healing events must progress in an ordered and programmed sequence both temporally and spatially, replicating key developmental events. A number of procedures have been employed to promote true and predictable regeneration of the periodontium. Principally, the approaches are based on the use of graft materials to compensate for the bone loss incurred as a result of periodontal disease, use of barrier membranes for guided tissue regeneration and use of bioactive molecules. More recently, the concept of tissue engineering has been integrated into research and applications of regenerative dentistry, including periodontics, to aim to manage damaged and lost oral tissues, through reconstruction and regeneration of the periodontium and alleviate the shortcomings of more conventional therapeutic options. The essential components for generating effective cellular based therapeutic strategies include a population of multi-potential progenitor cells, presence of signalling molecules/inductive morphogenic signals and a conductive extracellular matrix scaffold or appropriate delivery system. Mesenchymal stem cells are considered suitable candidates for cell-based tissue engineering strategies owing to their extensive expansion rate and potential to differentiate into cells of multiple organs and systems. Mesenchymal stem cells derived from multiple tissue sources have been investigated in pre-clinical animal studies and clinical settings for the treatment and regeneration of the periodontium.

Effect of conditioned medium from preameloblasts on regenerative cellular differentiation of the immature teeth with necrotic pulp and apical periodontitis.

INTRODUCTION: The purpose of this study was to investigate the effect of conditioned medium (CM) from murine preameloblasts on the cellular differentiation of mesenchymal stem cells (MSCs) in immature teeth with necrotic pulp and apical periodontitis. METHODS: Pulp necrosis and apical periodontitis were induced in 30 immature permanent double-rooted premolars of 3 beagles and were randomly assigned to the following treatment groups: group CM (n = 10), revascularization treatment was performed using CM from preameloblasts of C57BL/6 mice apical bud cells; group CR (n = 10), conventional revascularization treatment was performed; positive control group (n = 5), left infected; and negative control group (n = 5), untreated. The dogs were followed up for 12 weeks and assessed for treatment outcomes with radiographic and histologic analyses. The effect of the CM on sequential Runx2 and osterix messenger RNA gene expression during the differentiation of MG63 osteoblastlike cells was analyzed with real-time polymerase chain reaction. RESULTS: The overall treatment outcomes were not significantly different between the 2 treatment groups. However, the teeth in the CM group showed significantly more mature apices and a higher degree of hard tissue formation with projections intercalating into the pre-existing root dentin (P < .05). In CM-treated teeth, regenerated pulplike tissue was more frequently observed (P < .05). During differentiation, the CM induced early peak expression of Runx2 followed by sustained osterix overexpression. CONCLUSIONS: CM from preameloblasts rendered a favorable effect in providing a physiologic microenvironment for the differentiation of MSCs after revascularization treatment.

Understanding root resorption with diagnostic imaging.

This article presents the clinical, radiographic and histopathologic features of various types of tooth root resorption. Tooth resorption may occur in a tooth internally or externally with distinctively different treatment approaches for each type of resorption. Given that proper diagnosis of the type of resorption is important, the use of cone beam computed tomography (CBCT) and conventional 2-D intraoral images in evaluation of resorptive lesions is discussed.

Pulp regeneration after non-infected and infected necrosis, what type of tissue do we want? A review.

Regeneration (revitalization) of infected necrotic pulp tissue has been an important issue in endodontics for more than a decade. Based on a series of case reports, there appears to be evidence that new soft tissue can enter the root canal with a potential for subsequent hard tissue deposition resulting in a narrowing of the root canal. Very little is presently known about the exact nature of this tissue growing into the canal and how it may behave in the long term. In the case of regeneration of necrotic non-infected pulp tissue, a series of clinical and histological studies have shown that such events may take place in four variants: (i) Revascularization of the pulp with accelerated dentin formation leading to pulp canal obliteration. This event has a good long-term prognosis. (ii) Ingrowth of cementum and periodontal ligament (PDL). The long-term prognosis for this event is not known. (iii) Ingrowth of cementum, PDL, and bone. The long-term prognosis is only partly known, but cases developing an internal ankylosis have been described. (iv) Ingrowth of bone and bone marrow is a rare phenomenon and the long-term prognosis does not appear to be good. Based on current knowledge, expectations with respect to pulp regeneration (revitalization) of infected necrotic dental pulps are difficult to predict; more information than now available is needed before procedures for pulpal regeneration can be routinely recommended with a predictable long-term prognosis.

F-spondin inhibits migration and differentiation of osteoclastic precursors.

BACKGROUND: Clinically, severe cemental resorption is a rare consequence of periodontitis, although alveolar bone resorption by osteoclasts is one of the main pathologic changes. F-spondin is a secreted neuronal glycoprotein that localizes to the cementum. F-spondin is among the cementum-specific factors in periodontal tissue that have been reported. However, the effects of F-spondin on osteoclastogenesis have not yet been established. We examined the effects of F-spondin on stages of osteoclastogenesis, migration, and differentiation in a mouse osteoclastic precursor model, RAW 264 cells. METHODS: RAW 264 cells were treated with recombinant F-spondin. Macrophage colony stimulating factor (M-CSF)-induced cell migration was examined by migration assay performed with cell culture inserts. Osteoclastic differentiation was measured by counting tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells. RESULTS: In a transmigration assay, F-spondin significantly downregulated M-CSF-induced cell migration. Further, F-spondin significantly reduced the number of receptor activator of nuclear factor-kappa B ligand-induced TRAP-positive multinucleated cells. The receptor-associated protein, an antagonist of the low-density lipoprotein (LDL) receptor family, blocked the effects of F-spondin on M-CSF-induced migration. The suppressive effect of F-spondin on M-CSF-induced cell migration was blocked by knockdown of LDL receptor-related protein 8 (LRP8), a member of the LDL receptor family. CONCLUSIONS: Our findings suggest that F-spondin downregulates recruitment to the root side of periodontal tissue via LRP8 and inhibits differentiation of osteoclastic precursors. It is suggested that F-spondin is essential to protect the root surface from resorption.

VDR deficiency affects alveolar bone and cementum apposition in mice.

OBJECTIVE: To compare the mineralisation density (MD), morphology and histology of alveolar bone and cementum amongst VDR +/+, VDR -/-, and VDR -/- groups supplemented with a diet TD 96348, containing 20% lactose, 2.0% calcium and 1.25% phosphorous. METHODS: Four groups of mice (6 mice/group) were identified by genotyping: VDR +/+ mice (VDR wild type), VDR -/- mice (VDR deficient), VDR -/- offsprings derived from VDR -/- parents receiving a supplemental diet (early rescued), and VDR -/- mice fed with a supplemental diet beginning at age one month (late rescued). All mice were sacrificed at age 70.5 days. Micro-CT was used to compare MD and morphology of alveolar bone and cementum. H-E and Toluidine blue staining was used to examine the ultrastructure of the alveolar bone and cementum at matched locations. RESULTS: In VDR -/- group, alveolar bone and cementum failed to mineralise normally. Early rescue increased MD of alveolar bone in VDR -/- mice with excessive alveolar bone formation, but which not observed in late rescue group. MD and morphology of cementum-dentine complex in both early and late rescue groups were comparable with VDR +/+ group when feeding with high-calcium rescue diet. CONCLUSIONS: VDR affects alveolar bone mineralisation and formation systemically and locally. However, cementum apposition and mineralisation is mainly regulated by calcium concentrations in serum.

Repair of root resorption 4 and 8 weeks after application of continuous light and heavy forces on premolars for 4 weeks: a histology study.

INTRODUCTION: Repair of root resorption cavities has been studied under light microscopy, scanning electron microscopy, and transmission electron microscopy. The aim of this investigation was to demonstrate the use of microcomputed tomography (micro-CT) to assist in the identification of the region of interest for light microscopy preparation. This study also qualitatively illustrated the root resorption craters with 4 or 8 weeks of retention after 4 weeks of continuous light or heavy orthodontic force application. METHODS: Four patients who required bilateral extractions of maxillary first premolars as part of their orthodontic treatment were divided into 2 groups (groups I and II) of 2. The maxillary left and right first premolars were loaded with light (25 g) or heavy (225 g) orthodontic force for 4 weeks. After 4 or 8 weeks of retention, the maxillary first premolars were extracted. The extracted teeth were investigated with micro-CT. By using 3-dimensional images created by the micro-CT, the largest resorption craters on the buccal and lingual sides were identified. Parasagittal sections of these resorption craters were studied histologically under hematoxylin and eosin staining. RESULTS: The use of micro-CT improved the efficiency and accuracy of histologic techniques. Comparatively, less root resorption was repaired by new cementum after heavy orthodontic force application and short retention time. The reparative processes seemed to depend on time, with longer retention time yielding the most amount of repair. Reparative cementum was a mixture of acellular and cellular cementum. Reparative processes seemed to commence at the central part of the resorption cavity and expand to the periphery. CONCLUSIONS: Root resorption cavities have the potential to repair regardless of the orthodontic force magnitude. Correlative microscopy with micro-CT and conventional light microscopy adds a new dimension to current root resorption investigation techniques.

Repair of root resorption 2 to 16 weeks after the application of continuous forces on maxillary first molars in rats: a 2- and 3-dimensional quantitative evaluation.

INTRODUCTION: Root resorption is a side effect of orthodontic treatment that occurs with the removal of hyalinized tissue. Studies have shown that a reparative process in the periodontium begins when the applied orthodontic force is discontinued or reduced below a certain level. However, quantitative 3-dimensional evaluation of root resorption repair has not been done. The aim of this study was to quantitatively assess the 2- and 3-dimensional changes of root resorption craters after 2 weeks of continuous mesially applied orthodontic forces of 50 g on rat molars and 2- to 16-week retention periods. METHODS: We used 60 male Wistar rats (10 weeks old). Nickel-titanium closed-coil springs were used to apply 50-g mesial forces for 2 weeks to move the maxillary left first molars. The rats were randomly allocated to 6 groups. Those in the zero-week retention group were killed after force application. In the remaining 5 groups, the interdental spaces between the maxillary first and second molars were filled with resin to retain the molars. The molars were extracted after periods of retention from 2 and 16 weeks. The maxillary right molars were used as the controls. Mesial and distal roots (distobuccal and distopalatal) were examined by using scanning electron and 3-dimensional scanning laser microscopes. The surface area, depth, volume, and roughness of the root resorption craters were measured. RESULTS: The area, depth, and volume of the craters decreased gradually and showed similar trends over the retention time, approaching a plateau at the 12th week. After 16 weeks of retention, the volumes of the resorption craters of the distobuccal and distopalatal roots reached recovery peaks of 69.5% and 66.7%, respectively. Small pits on the mesial roots showed recovery of 62.5% at the 12th week. The healing patterns in distal roots with severe resorption and mesial roots with shallow resorption had no significant differences. CONCLUSIONS: The resorption and repair processes during the early stages of retention are balanced, and most of the reparative process occurs after 4 weeks of passive retention after the application of orthodontic force. Frequent orthodontic reactivations should be avoided to allow recovery and repair of root surface damage.

Stem cell regulatory gene expression in human adult dental pulp and periodontal ligament cells undergoing odontogenic/osteogenic differentiation.

INTRODUCTION: During development and regeneration, odontogenesis and osteogenesis are initiated by a cascade of signals driven by several master regulatory genes. METHODS: In this study, we investigated the differential expression of 84 stem cell-related genes in dental pulp cells (DPCs) and periodontal ligament cells (PDLCs) undergoing odontogenic/osteogenic differentiation. RESULTS: Our results showed that, although there was considerable overlap, certain genes had more differential expression in PDLCs than in DPCs. CCND2, DLL1, and MME were the major upregulated genes in both PDLCs and DPCs, whereas KRT15 was the only gene significantly downregulated in PDLCs and DPCs in both odontogenic and osteogenic differentiation. Interestingly, a large number of regulatory genes in odontogenic and osteogenic differentiation interact or crosstalk via Notch, Wnt, transforming growth factor beta (TGF-beta)/bone morphogenic protein (BMP), and cadherin signaling pathways, such as the regulation of APC, DLL1, CCND2, BMP2, and CDH1. Using a rat dental pulp and periodontal defect model, the expression and distribution of both BMP2 and CDH1 have been verified for their spatial localization in dental pulp and periodontal tissue regeneration. CONCLUSIONS: This study has generated an overview of stem cell-related gene expression in DPCs and PDLCs during odontogenic/osteogenic differentiation and revealed that these genes may interact through the Notch, Wnt, TGF-beta/BMP, and cadherin signaling pathways to play a crucial role in determining the fate of dental derived cell and dental tissue regeneration. These findings provided a new insight into the molecular mechanisms of the dental tissue mineralization and regeneration.

Physical properties of root cementum: part 11. Continuous vs intermittent controlled orthodontic forces on root resorption. A microcomputed-tomography study.

INTRODUCTION: There is still ambiguity about whether continuous or intermittent orthodontic forces produce more root resorption. This prospective randomized clinical trial was designed to compare root resorption with these 2 force application patterns. METHODS: The sample consisted of 16 maxillary first premolars from 8 patients who required bilateral extractions as part of their orthodontic treatment. In each subject, a fixed experimental appliance was placed on the maxillary teeth on each side, allowing a buccally directed force. The force was generated by a segmental wire of beta-titanium-molybdenum alloy. The first premolar on 1 side received a buccally directed continuous force, and the contralateral premolar received intermittent force. The initial force magnitude for both sides was 225 cN. After 14 days of initial continuous force, the intermittent force application was obtained with subsequently repeated periods until the end of the eighth week of a 3-day rest period followed by a 4-day force application period. Force levels were set to 225 cN at each patient visit. After the experimental period of 8 weeks, the teeth were extracted under a strict protocol to prevent root surface damage and analyzed with a microcomputed-tomography scan system, and specially designed software was used for direct volumetric measurements. RESULTS: Intermittent force produced less root resorption than continuous force (P <0.05). Analysis by position showed that the buccal-cervical region had significantly more root resorption than the other positions (P <0.001), corresponding to a region of compression generated by tipping. CONCLUSIONS: The application of intermittent orthodontic forces of 225 cN for 8 weeks (14 days of force application, 3 days of rest, then 4 days of force application repeated for 6 weeks) caused less root resorption than continuous forces of 225 cN for 8 weeks. Although it might not be clinically practical, compared with continuous forces, intermittent forces might be a safer method to prevent significant root resorption. This regimen, however, could compromise the efficiency of tooth movement.

Structure and mechanical properties of Ank/Ank mutant mouse dental tissues--an animal model for studying periodontal regeneration.

Enamel, dentine and cementum are dental tissues with distinct functional properties associated with their unique hierarchical structures. Some potential ways to repair or regenerate lost tooth structures have been revealed in our studies focused on examining teeth obtained from mice with mutations at the mouse progressive ankylosis (ank) locus. Previous studies have shown that mice with such mutations have decreased levels of extracellular inorganic pyrophosphate (PP(i)) at local sites resulting in ectopic calcification in joint areas and in formation of a significantly thicker cementum layer when compared with age-matched wild-type (WT) tissue [Ho AM, Johnson MD, Kingsley DM. Role of the mouse ank gene in control of tissue calcification and arthritis. Science 2000;289:265-70; Nociti Jr FH, Berry JE, Foster BL, Gurley KA, Kingsley DM, Takata T, et al. Cementum: a phosphate-sensitive tissue. J Dent Res 2002;81:817-21]. As a next step, to determine the quality of the cementum tissue formed in mice with a mutation in the ank gene (ank/ank), we compared the microstructure and mechanical properties of cementum and other dental tissues in mature ank/ank vs. age-matched WT mice. Backscattered scanning electron microscopy (SEM) imaging and transmission electron microscopy (TEM) analyses on mineralized tissues revealed no decrease in the extent of mineralization between ank/ank cementum vs. WT controls. Atomic-force-microscopy-based nanoindentation performed on enamel, dentine or cementum of ank/ank vs. age-matched WT molars revealed no significant difference in any of the tested tissues in terms of hardness and elastic modulus. These results indicate that the tissue quality was not compromised in ank/ank mice despite faster rate of formation and more abundant cementum when compared with age-matched WT mice. In conclusion, these data suggest that this animal model can be utilized for studies focused on defining mechanisms to promote cementum formation without loss of mechanical integrity.

Regeneration of bone and periodontal ligament induced by recombinant amelogenin after periodontitis.

Regeneration of mineralized tissues affected by chronic diseases comprises a major scientific and clinical challenge. Periodontitis, one such prevalent disease, involves destruction of the tooth-supporting tissues, alveolar bone, periodontal-ligament and cementum, often leading to tooth loss. In 1997, it became clear that, in addition to their function in enamel formation, the hydrophobic ectodermal enamel matrix proteins (EMPs) play a role in the regeneration of these periodontal tissues. The epithelial EMPs are a heterogeneous mixture of polypeptides encoded by several genes. It was not clear, however, which of these many EMPs induces the regeneration and what mechanisms are involved. Here we show that a single recombinant human amelogenin protein (rHAM(+)), induced in vivo regeneration of all tooth-supporting tissues after creation of experimental periodontitis in a dog model. To further understand the regeneration process, amelogenin expression was detected in normal and regenerating cells of the alveolar bone (osteocytes, osteoblasts and osteoclasts), periodontal ligament, cementum and in bone marrow stromal cells. Amelogenin expression was highest in areas of high bone turnover and activity. Further studies showed that during the first 2 weeks after application, rHAM(+) induced, directly or indirectly, significant recruitment of mesenchymal progenitor cells, which later differentiated to form the regenerated periodontal tissues. The ability of a single protein to bring about regeneration of all periodontal tissues, in the correct spatio-temporal order, through recruitment of mesenchymal progenitor cells, could pave the way for development of new therapeutic devices for treatment of periodontal, bone and ligament diseases based on rHAM(+).

FEM analysis of different dental root canal-post systems in young permanent teeth.

AIM: Aim of this work was to carry out a comparative evaluation of the structural behaviour of different root canal posts (cylindrical, conical and triple conical) fitted in a second lower bicuspid and subjected to compression and bending test. MATERIALS AND METHODS: This study has been carried out by numerical method of structural analysis of finite elements (FEM, Finite Element Method). Different tridimensional models were obtained by CAT images of an extracted tooth, endodontically treated, filled with guttapercha and triple conical glass post. Images have been elaborated by a software for images (Mimics and Ansys) and CAD (Rhinoceros 3 D). In the models a II Class restoration has been virtually created. In the numerical simulation dental tissues (enamel, dentine and root cement), guttapercha, root canal cement, different posts, different techniques of cementation and crown restoration (composites and adhesive systems) have been considered. RESULTS: Strain distributions in dental tissues, in root canal cement and in posts have been compared. The equivalent tensions and the single components (traction, compression and cut) have been analysed. In all examined posts, the most strained part is resulted the coronal one, even if the total tension, in the different tooth-post analyzed systems, resulted uniformly distributed. A similar behaviour was shown by the root canal cement. CONCLUSIONS: According to the analyzed conditions of bond and load, varying according to the geometry of the considered posts, our results confirm that there is no substantial difference of deformation in posts, root canal cement and treated tooth.

The side effects of orthodontic mechanics in orthodontic treatments.

The side effects of orthodontic mechanics at each tissue level (alveolar bone, periodontal ligament, gingiva, pulp, cementum, and enamel) are addressed, along with the issue of pain following orthodontic appointments, and psychobehavioral alterations observed in orthodontic patients. It is necessary to know how orthodontic treatment affects enamel health, including methods to manage these side effects, which are still a dilemma for orthodontic clinicians. It is interesting to note that the dental pulp, which lies deep in the tooth core, also reacts to orthodontic force. The way the periodontal ligament responds to light and heavy forces, in young and adult patients, with or without periodontal disease, should be considered. Root resorption is a well-recognized phenomenon following orthodontic treatment. Advances made in this area of research to identify the parameters and genes associated with this process are developing.

Intrusion of teeth with class III furcation: a clinical, histologic and histometric study in dogs.

AIM: To assess orthodontic intrusion effects on periodontal tissues in dogs' pre-molars with class III furcations treated with open flap debridement (OFD) or with guided tissue regeneration (GTR) associated to bone autograft (BA). MATERIAL AND METHODS: Class III furcations were created in the pre-molars of seven mongrel dogs. After 75 days, teeth were randomly treated with OFD or GTR/BA. After 1 month, metallic crowns were assembled on pre-molars and connected apically to mini-implants by nickel-titanium springs. Teeth were randomly assigned to orthodontic intrusion (OFD+I and GTR/BA+I) groups or no movement (OFD and GTR/BA) groups. Dogs were sacrificed after 3 months of movement and 1 month retention. RESULTS: All class III furcations were closed or reduced to class II or I in the intrusion groups, while 50% of the lesions in non-moved teeth remained unchanged. Intruded teeth presented higher probing depth and lower gingival marginal level than non-moved teeth (p<0.01). Clinical attachment gain was reduced in the intrusion groups by the end of retention (p<0.05). OFD+I presented smaller soft tissue area and larger bone tissue area than other groups (p<0.05). CONCLUSION: Orthodontic intrusion with anchorage via mini-implants improved the healing of class III furcation defects after OFD in dogs. GTR/BA impaired those results.

PGE2 activates cementoclastogenesis by cementoblasts via EP4.

Destruction of cementum and alveolar bone is the main causative event for the exfoliation of teeth as a consequence of periodontitis. Prostaglandin E(2) (PGE(2)) and PGE receptor subtypes (EPs) play an important role in modulating osteoblast-mediated osteoclastogenesis; however, no information is available on the role of PGE(2) and EPs in regulating cementoblast-mediated cementoclastogenesis. We hypothesized that the PGE(2)-EPs pathway also regulates cementoblasts' ability to activate cementoclasts. For these studies, OCCM-30 cells (a mouse cementoblast cell line) were exposed to PGE(2) and specific EP agonists. PGE(2) (100 ng/mL) and EP4 agonist (1 microM) up-regulated RANKL and IL-6 mRNA levels, while they down-regulated OPG mRNA expression. The EP4 antagonist (1 microM) eliminated these effects of PGE(2). PGE(2) treatment of co-cultures of OCCM-30 cells with bone marrow cells induced TRAP-positive cells via the EP4 pathway. These findings suggest that PGE(2) promotes cementoblast-mediated cementoclastogenesis by regulating the expression of RANKL and OPG via the EP4 pathway.