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Cementum
Kinds of Cementum Terms modified by Cementum Selected AbstractsLocalization of SOST/sclerostin in cementocytes in vivo and in mineralizing periodontal ligament cells in vitroJOURNAL OF PERIODONTAL RESEARCH, Issue 2 2010A. Jäger Jäger A, Götz W, Lossdörfer S, Rath-Deschner B. Localization of SOST/sclerostin in cementocytes in vivo and in mineralizing periodontal ligament cells in vitro. J Periodont Res 2009; doi: 10.1111/j.1600-0765.2009.01227.x. © 2009 John Wiley & Sons A/S Background and Objective:, Cementum and bone are rather similar hard tissues, and osteocytes and cementocytes, together with their canalicular network, share many morphological and cell biological characteristics. However, there is no clear evidence that cementocytes have a function in tissue homeostasis of cementum comparable to that of osteocytes in bone. Recent studies have established an important role for the secreted glycoprotein sclerostin, the product of the SOST gene, as an osteocyte-derived signal to control bone remodelling. In this study, we investigated the expression of sclerostin in cementocytes in vivo as well as the expression of SOST and sclerostin in periodontal ligament cell cultures following induction of mineralization. Material and Method:, Immunolocalization of sclerostin was performed in decalcified histological sections of mouse and human teeth and alveolar bone. Additionally, periodontal ligament cells from human donors were cultured in osteogenic conditions, namely in the presence of dexamethasone, ascorbic acid and ,-glycerophosphate, for up to 3 wk. The induction of calcified nodules was visualized by von Kossa stain. SOST mRNA was detected by real-time PCR, and the presence of sclerostin was verified using immunohistochemistry and western blots. Results:, Expression of sclerostin was demonstrated in osteocytes of mouse and human alveolar bone. Distinct immunolocalization in the cementocytes was shown. In periodontal ligament cultures, following mineralization treatment, increasing levels of SOST mRNA as well as of sclerostin protein could be verified. Conclusion:, The identification of SOST/sclerostin in cementocytes and mineralizing periodontal ligament cells adds to our understanding of the biology of the periodontium, but the functional meaning of these findings can only be unravelled after additional in vitro and in vivo studies. [source] Prostanoids induce egr1 gene expression in cementoblastic OCCM cellsJOURNAL OF PERIODONTAL RESEARCH, Issue 5 2007L. Pham Background and Objective:, Prostanoids that activate protein kinase C signaling are potent anabolic stimulators of cementoblastic OCCM cells. Using cDNA subtractive hybridization, we identified early growth response gene-1 (egr1) as a prostanoid-induced gene. Egr1, a zinc-finger transcription factor expressed during tooth development, regulates cell growth and differentiation. We hypothesize that Egr1 may mediate part of the prostanoid-induced anabolic effect in cementoblasts. Our objective was to characterize prostanoid-induced egr1 gene expression in OCCM cells. Material and Methods:, Total RNA and proteins were assayed by northern blot and western immunoblot assays. Results:, Prostaglandin E2 -, prostaglandin F2, - and fluprostenol-induced egr1 mRNA levels peaked at 0.5 h and returned to baseline by 4 h. Prostaglandin F2, and fluprostenol more potently induced egr1 compared with prostaglandin E2. The phorbol ester, phorbol 12-myristate 13-acetate, which activates protein kinase C signaling, induced egr1 mRNA levels 66-fold over the control, whereas forskolin (a cAMP-protein kinase A activator) and ionomycin (a calcium activator) had no effect. Protein kinase C inhibition significantly inhibited prostaglandin E2 -, prostaglandin F2, - and fluprostenol-induced egr1 mRNA levels. Finally, prostanoids maximally induced Egr1 protein at 1 h. Conclusion:,egr1 is a primary response gene induced by prostaglandin E2, prostaglandin F2, and fluprostenol in OCCM cells through protein kinase C signaling, suggesting that Egr1 may be a key mediator of anabolic responses in cementoblasts. Cementum is vital for periodontal organ maintenance and regeneration. Periodontal ligament fibers (Sharpey's fibers) insert into bone and cementum, thereby supporting the tooth in the alveolus (1). If the periodontal organ is lost, its regeneration requires cementoblast differentiation in order to form new cementum for periodontal ligament fiber insertion. Early attempts to regenerate cementum have proven difficult and rarely generate sufficient tissue (2). A better understanding of the molecular and cellular regulators that promote cementoblast differentiation is critical for developing targeted periodontal regeneration. [source] Mechanical behavior of bovine periodontal ligament under tension-compression cyclic displacementsEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 1 2006Tatsuya Shibata In the present study, the mechanical response of bovine periodontal ligament (PDL) subjected to displacement-controlled tension,compression harmonic oscillations and subsequent rupture was examined. Specimens including dentine, cementum, PDL, and alveolar bone were extracted from different depths and locations of bovine first molars. They were immersed in a saline solution at room temperature and clamped on their bone and dentine extremities. The samples were tested at ±35% of the PDL's width, with a frequency of 1 Hz. The mechanical parameters evaluated were hysteresis, phase lag, and the modulus of the stress,stretch ratio curves in tension and compression. The tensile strength and the corresponding stretch ratio were also recorded. Stress,stretch ratio curves indicated a non-linear, time-dependent response with hysteresis and preconditioning effects. The hysteresis and phase lag in compression were much higher than in tension, suggesting that the dissipated energy was higher in compression than in tension. The root depth and location did not play essential roles for the tension or compression data, with the exception of limited statistical differences for tensile strength and corresponding stretch ratio. Thus, biological variability in the specimens, as a result of different bone contours, PDL width, and fiber orientation, did not affect the energy-absorbing capacity of the PDL. The evolution of the stress rate with stress demonstrated a constant increase of stiffness with stress. The stiffness values were twofold higher in tension than in compression. The data also showed that the stiffness of the PDL was comparable with data reported for other soft tissues. [source] Immunocytochemical characterization of ectopic enamel deposits and cementicles in human teethEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 1 2003Dieter D. Bosshardt Despite the relative frequency and clinical relevance of radicular enamel deposits and cementicles, their etiology and nature are unknown. The purpose of the present study was therefore to evaluate the presence and distribution of mineralization-associated non-collagenous matrix proteins (NCPs) in various types of root-associated ectopic mineralizations. Human teeth were processed for embedding in epoxy or acrylic resins. Tissue sections were incubated with antibodies to amelogenins (AMEL), bone sialoprotein (BSP), and osteopontin (OPN). Radicular enamel deposits contained residual organic matrix that labeled for AMEL. In contrast, BSP and OPN were not detected in the residual enamel matrix, they were found in the cementum deposited on its surface as well as in collagen-free cementicle-like structures in the adjacent periodontal ligament. True cementicles consisted of a collagenous matrix intermixed with a non-collagenous ground substance. Labeling for BSP and OPN was mainly associated with the interfibrillar ground substance. No immunoreactivity for AMEL was detected in cementicles. These data indicate that ectopic enamel deposits on the root retain a high amount of AMEL, whereas cementicles contain BSP and OPN, two NCPs typically found in bone and cementum. These NCPs may, like in their normal tissue counterparts, play a role in the mineralization process. [source] On the origin of intrinsic matrix of acellular extrinsic fiber cementum: Studies on growing cementum pearls of normal and bisphosphonate-affected guinea pig molarsEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 3 2002Chantha K. Jayawardena Cementum pearls (CPs) belong to a type of acellular extrinsic fiber cementum (AEFC) that form on the maturing enamel of guinea pig molars. This study aimed to elucidate the forming process of intrinsic matrix of AEFC using the CPs of normal and bisphosphonate-affected guinea pig molars as experimental models. A group of guinea pigs were subjected to continuous administration of 1-hydroxyethylidene-1,1-bisphosphonate (HEBP) for 2 wk to inhibit mineralization of growing CPs. Fenestration of the enamel organ and migration of periodontal cells on to the exposed surface of maturing enamel appeared to be unaffected by HEBP, whereas de novo formation as well as growth of pre-existing CPs did not proceed under the same conditions. Immunoreactions for osteopontin were located exclusively on the mineralized matrix of preformed CPs, implying the absence of additional deposition or accumulation of putative intrinsic cementum matrix on the affected CPs, where the propagation of mineral phase had been arrested. In both normal and HEBP-treated groups, distinct enzymatic reactions for alkaline phosphatase appeared on the cells of the periodontal ligament associated closely with the sites of CP formation, and along the mineralization front of CPs. These observations suggest that the mineralization process per se plays a central role in the deposition of AEFC matrix and that alkaline phosphatase of periodontal cells penetrating through the enamel organ to the maturing enamel surface plays a key role in the mineralization process of CPs. [source] Characterization of a family with dominant hypophosphatasiaEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 3 2000Jan C.-C. A kindred with dominant hypophosphatasia resulting from an alanine to threonine substitution at position 99 of the alkaline phosphatase protein is described. The clinical findings of individual members of the kindred were assessed by oral and physical examinations, or from the descriptions of multiple family members. The proband displayed enamel hypoplasia and premature loss of fully rooted primary anterior teeth, which were shown by histological examination to lack cementum. Serum alkaline phosphatase (ALP) and a vitamin B6 panel, and urine phosphoethanolamine (PEA) were measured on 21 family members. Based upon the clinical and laboratory tests, affected and unaffected status was assigned. Parametric linkage analysis of the kindred using different dominant models and frequency distributions for the disease allele and the mutation gave lodscores >4.2 and confirmed the strong linkage between the disease and the mutation. Assuming the defined mutation causes the disease, the reliability of clinical and laboratory tests is assessed. [source] Cemental tear: a case reportINTERNATIONAL ENDODONTIC JOURNAL, Issue 1 2006M. L. Stewart Abstract Aim, To report a case of a cemental tear. Summary, A case is reported of a patient with a history of trauma, root canal treatment and retreatment procedures to eliminate recurring sinus tracts. An exploratory surgery, extraction, and biopsy resulted in a diagnosis of cemental tear. Key learning points, ,,The detachment of a fragment of cementum is described as a cemental tear. ,,Cemental tears have been reported in the periodontal literature associated with localized, rapid periodontal breakdown. Common causative factors are aging and traumatic occlusion but the exact aetiology is unknown. ,,Trauma may be considered as a potential aetiologic factor for cemental tears in addition to occlusal traumatism and aging. [source] Effect of different irrigation solutions and calcium hydroxide on bacterial LPSINTERNATIONAL ENDODONTIC JOURNAL, Issue 11 2003J. M. G. Tanomaru Abstract Aim, To evaluate the effect of biomechanical preparation with different irrigating solutions and calcium hydroxide dressing in dog root canals containing bacterial endotoxin (lipopolysaccharides; LPS). Methodology, One hundred and forty premolar roots from seven dogs were filled with Escherichia coli LPS for 10 days (three roots were lost during histological processing). The following irrigating solutions were used for biomechanical preparation: 1% (group I, n = 20), 2.5% (group II, n = 19) and 5% sodium hypochlorite (group III, n = 19), 2% chlorhexidine digluconate (group IV, n = 20) and physiological saline solution (group V, n = 19). In group VI (n = 20), the LPS solution was maintained in the root canal during the entire experiment and in group VII (n = 20), after biomechanical preparation with saline solution, the root canals were filled with a calcium hydroxide dressing (Calen; control). After 60 days, the animals were sacrificed and the following parameters of periapical disease were evaluated: (a) inflammatory infiltrate, (b) periodontal ligament thickness, (c) cementum resorption and (d) bone resorption. Scores were given and data were analysed statistically with the Kruskal,Wallis and Dunn tests (P < 0.05). Results, Histopathological evaluation showed that groups I,VI had more inflammatory infiltrate, greater periodontal ligament thickening and greater cementum and bone resorption (P < 0.05) compared to group VII, which received the calcium hydroxide intracanal dressing. Conclusions, Biomechanical preparation with the irrigating solutions did not inactivate the effects of the endotoxin but the calcium hydroxide intracanal dressing did appear to inactivate the effects induced by the endotoxin in vivo. [source] Growth factors in periodontal regenerationINTERNATIONAL JOURNAL OF DENTAL HYGIENE, Issue 2 2009S Raja Abstract:, Inflammatory periodontal disease is an almost ubiquitous disorder in the adult population. Cases or sites with moderate to advanced disease often continue to show signs of inflammation after non-surgical approach. Our current understanding of periodontal healing is based on a hypothesis by Melcher who proposed that the cell type that repopulates the exposed root surface at the periodontal repair site will define the nature of the attachment/repair that take place. If mesenchymal cells from periodontal ligament/perivascular region of the bone proliferate and colonize the root surface, regeneration occurs. Growth factors are natural cell products that are released or activated when cell division is needed. This action typically occurs during such events as wound healing or tissue regeneration. Activated platelets at the wound margins release several growth factors such as platelet-derived growth factor (PDGF), transforming growth factor (TGF)-,, epidermal growth factor etc. Cells adjacent to the injured site also are induced to release growth factors such as insulin-like growth factor-I, PDGF, TGF-, and TGF-, within a few hours after injury. In periodontal regeneration, the coronal re-establishment of the periodontal ligament (PDL) is required together with corresponding cementum and supporting alveolar bone. Thus, agents which promote periodontal ligament fibroblast (PLF) proliferation and migration as well as collagen biosynthesis would appear to be mediators for enhancing new PDL formation. When combinations or cocktails of different factors are used, greater repair is achieved than when individual factors are applied. [source] Digital cementum luminance analysis (DCLA): a tool for the analysis of climatic and seasonal signals in dental cementumINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 1 2008C. M. Wall-Scheffler Abstract Cementum banding patterns have been used by archaeozoologists and wildlife managers for a number of decades to assess the season and age at death of mammalian populations. However, the observation and measurement of the nature of cementum banding, especially that of the final band, has proved to be difficult except under conditions of excellent preservation and advanced microscopy. The research presented here details a method for extracting luminance data from the banding patterns of cementum in order to quantify the optical properties of cementum tissue. By doing so, analysis of the relationship between cementum deposition and environmental variables is achieved. We present the results of a digital cementum luminance analysis (DCLA) on a sample of first molars from two species, Ovis aries, Soay and Capra ibex. The results indicate that significant relationships occur between seasonal temperature changes and cementum histology. Furthermore, we show that luminance values can be used to assess the geographical range of genetically similar populations. Our results demonstrate that the study of luminance is a vital tool for the quantitative study of dental cementum for both archaeological and ecological studies. Copyright © 2007 John Wiley & Sons, Ltd. [source] Comparing methods for analysing mortality profiles in zooarchaeological and palaeontological samplesINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 6 2005T. E. Steele Abstract In this study, I examine three methods that are currently used for comparing mortality profiles from zooarchaeological and palaeontological samples: (1) histograms with 10% of life-span age classes; (2) boxplots showing tooth crown height medians; and (3) triangular plots of the proportions of young, prime and old animals. I assess the advantages and disadvantages of each method using data collected on two samples of Northern Yellowstone elk (Cervus elaphus nelsoni) with known, or cementum annuli-determined, ages at death. One sample was hunted by wolves (n,=,96), and the other was hunted by recent humans using rifles (n,=,226). I tested each method with the known or cementum annuli age distributions and with age estimation techniques appropriate for archaeological assemblages. Histograms are best used when the relationship between dental eruption/attrition and age is well established so that individuals can be confidently assigned into 10% of life-span groups, and when more than 30 or 40 individuals are present in the assemblage. Boxplots employ raw crown heights, thus removing the error introduced by assigning specimens to age classes, and therefore they allow the analysis of species where the relationship between dental eruption/attrition and age is unknown. Confidence intervals around the medians allow samples to be statistically compared. Triangular plots are easy to use and allow multiple samples and species to be considered simultaneously, but samples cannot be statistically compared. Modified triangular plots bootstrap samples to provide 95% confidence ellipses, allowing for statistical comparisons between samples. When possible, samples should be examined using multiple methods to increase confidence in the results. Copyright © 2005 John Wiley & Sons, Ltd. [source] Role of D1 and E Cyclins in Cell Cycle Progression of Human Fibroblasts Adhering to Cementum Attachment Protein,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 6 2001Takayoshi Yokokoji Abstract Cementum attachment protein (CAP) is a collagenous protein present in the matrix of tooth cementum that mediates preferential attachment of some mesenchymal cell types, and CAP binding capacity is related to mineralizing tissue-forming capacity in culture. We have examined if adhesion to surfaces containing CAP as the only attachment protein permits human fibroblasts to escape G1 arrest and synthesize DNA, and if adhesion to CAP modulates the levels of cyclins D1 and E. Human gingival fibroblasts (HGFs) were serum-starved, trypsinized, and added to plates coated with CAP or bovine serum albumin (BSA). Cells were then exposed to either 10% fetal bovine serum (FBS) or to cementum-derived growth factor (CGF), an insulin-like growth factor I (IGF-I)-like molecule sequestered in tooth cementum, plus epidermal growth factor (EGF). DNA synthesis was measured as [3H]thymidine uptake, and cyclin D1 and E levels were determined by Western analysis. Cyclin E-dependent kinase (Cdk) activity was assessed in terms of H1 kinase activity in immunoprecipitates of cyclin E. Cells adhering to CAP synthesized DNA, whereas on BSA they remained unattached and did not synthesize DNA. Protein levels of cyclin D1 were higher in cells adhering to CAP in the absence and presence of growth factors. Cyclin E levels were not affected by adhesion alone, but they increased in the presence of growth factors. Cyclin E-associated kinase activity was higher in cells adherent on CAP, and it increased further in the presence of growth factors. Our results indicate that adhesion to CAP increases cyclin D1 levels and cyclin E-associated Cdk activity, and that these increases contribute to cell cycle progression. We previously observed that the signaling reactions induced during adhesion are characteristic of the CAP; together these observations indicate that specific matrix components present in the local environment can contribute to recruitment and differentiation of specific cell types for normal homeostasis and wound healing. [source] Periodontal wound healing/regeneration following the application of rhGDF-5 in a , -TCP/PLGA carrier in critical-size supra-alveolar periodontal defects in dogsJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 7 2010David H. Kwon Kwon DH, Bisch FC, Herold RW, Pompe C, Bastone P, Rodriguez NA, Susin C, Wikesjö UM. Periodontal wound healing/regeneration following application of rhGDF-5 in a , -TCP/PLGA carrier in critical-size supra-alveolar periodontal defects in dogs. J Clin Periodontol 2010; 37: 667,674. doi: 10.1111/j.1600-051X.2010.01569.x. Abstract Aim: The objective of this study was to evaluate the effect of a novel recombinant human GDF-5 (rhGDF-5) construct intended for onlay and inlay indications on periodontal wound healing/regeneration. Methods: Contralateral, surgically created, critical-size, 6-mm, supra-alveolar periodontal defects in five adult Hound Labrador mongrel dogs received rhGDF-5 coated onto , -tricalcium phosphate (, -TCP) particles and immersed in a bioresorbable poly(lactic- co -glycolic acid) (PLGA) composite or the , -TCP/PLGA carrier alone (control). The rhGDF-5 and control constructs were moulded around the teeth and allowed to set. The gingival flaps were then advanced; flap margins were adapted 3,4 mm coronal to the teeth and sutured. The animals were euthanized at 8 weeks post-surgery when block biopsies were collected for histometric analysis. Results: Healing was generally uneventful. A few sites exhibited minor exposures. Three control sites and one rhGDF-5 site (in separate animals) experienced more extensive wound dehiscencies. The rhGDF-5 and control constructs were easy to apply and exhibited adequate structural integrity to support the mucoperiosteal flaps in this challenging onlay model. Limited residual , -TCP particles were observed at 8 weeks for both rhGDF-5/, -TCP/PLGA and , -TCP/PLGA control sites. The rhGDF-5/, -TCP/PLGA sites showed significantly greater cementum (2.34 ± 0.44 versus 1.13 ± 0.25 mm, p=0.02) and bone (2.92 ± 0.66 versus 1.21 ± 0.30 mm, p=0.02) formation compared with the carrier control. Limited ankylosis was observed in four of five rhGDF-5/, -TCP/PLGA sites but not in control sites. Conclusions: Within the limitations of this study, the results suggest that rhGDF-5 is a promising candidate technology in support of periodontal wound healing/regeneration. Carrier and rhGDF-5 dose optimization are necessary before further advancement of the technology towards clinical evaluation. [source] Clinical and histological evaluation of an acellular dermal matrix allograft in combination with the coronally advanced flap in the treatment of miller class I recession defects: an experimental study in the mini-pigJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 6 2009Javier Núñez Abstract Objectives: To study the wound healing of acellular dermal matrix (ADM) allografts when used together with coronally advanced flaps (CAF) in the treatment of localized gingival recessions in the mini-pig experimental model. Material and Methods: Dehiscence defects 4 × 5 mm were surgically created in one buccal root surface in each quadrant of PI, II, or III in three mini-pigs. They were then treated with CAF and the interposition of either a connective tissue graft (CTG) or ADM. As the primary outcome, the histological interface between the ADM and the root surface was studied and was compared with CTG. As secondary outcomes, we assessed the amount and quality of the keratinized tissue and clinical outcomes in terms of root coverage and recession reduction. Results: At 3 months, the CTG group attained a mean 76% root coverage, versus 62% in the ADM group. The histological interface with the root surface was similar in both groups. The apical migration of the epithelium was 1.79±0.46 mm for the CTG and 1.21±0.35 mm for ADM. Newly formed cementum was observed with both treatments. New bone and a newly formed periodontal ligament were shown in five specimens in the ADM group and in three in the CTG group. Conclusion: Both materials showed similar clinical and histological outcomes. [source] Fibre retention osseous resective surgery: a novel conservative approach for pocket eliminationJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 2 2007Gianfranco Carnevale Abstract Aim and Background: The position of the most apical inter-dental portion of the alveolar crest is classically used in osseous resective surgery (ORS) to establish the amount of the inter-proximal and buccal/lingual bone resection. Supracrestal fibres connected to the root cementum are always present coronal to the alveolar crest both in healthy and diseased sites. The aim of this paper is to report a novel surgical approach that combines the classical method of osseous resection with the gingival fibre retention technique. Material and Methods: A description of the surgical procedure in four steps is provided (flap design, marginal soft tissue removal and fibre retention, ORS, suture of the flap). Results and Conclusion: The proposed technique shifts the bottom of the defect in a more coronal position at the level of the connective tissue fibre attachment, establishing a more conservative supporting bone resection. [source] Susceptibility of GTR-regenerated periodontal attachment to ligature-induced periodontitisJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 5 2004An experiment in the monkey Abstract Aim: This study aimed to compare the susceptibility of guided tissue regeneration (GTR)-regenerated periodontal attachment to ligature-induced periodontitis with that of the pristine periodontium. Methods: Periodontal breakdown was produced in four monkeys by the placement of orthodontic elastics around experimental teeth (test teeth). During a flap operation, the root surfaces were scaled and planed, and a notch indicating the apical termination of scaling and root planing was made in the root surface. Following resection of the crowns and endodontic treatment, an e-PTFE membrane was adapted over the roots. Subsequently, the flaps were sutured to complete closure of the wound (submerged). At membrane removal after 5 weeks, the crowns of the contralateral teeth serving as controls were resected, and the roots treated endodontically during a flap operation. Artificial composite crowns were then placed on both test and control roots. After 3 months of tooth cleaning, cotton floss ligatures were placed passively around both test and control teeth for a period of 6 months. Two weeks later the animals were sacrificed. Results: Histological analysis demonstrated that the instrumented root surfaces of the test teeth were covered by newly formed cementum of the reparative, cellular, extrinsic and intrinsic fiber type, while the cementum on the controls was mainly acellular extrinsic fiber cementum. Histometric assessments demonstrated that similar attachment loss had occurred on test (1.0±0.5 mm) and control roots (1.0±0.4 mm) during the 6 months of ligature-induced plaque accumulation. Conclusion: The results indicate that teeth with a periodontal attachment apparatus formed by GTR is not more susceptible to periodontitis than those with a pristine periodontium. [source] In vitro evaluation of novel low abrasive air polishing powdersJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 1 2003G. J. Petersilka Abstract Aim of the study: Though efficient in stain and plaque removal, air polishing is highly abrasive on root cementum or dentin even if working parameters are adjusted to minimize damage. As abrasiveness is also influenced by the physical properties of the powders used, the aim of the study was to evaluate the safety of novel low abrasive air polishing powders in vitro. Material and methods: Using four novel air polishing powders (A, B, C and D) and a standard sodium bicarbonate (NaHCO3) powder, roots of 126 extracted teeth were air polished under standardized conditions at various working parameter combinations (distance: 2 mm, 4 mm and 6 mm; powder and water setting: low, medium and high) at an angulation of 90° for 20 s. Instrumentation was performed in triplicate; resulting root defects were quantified laser-optically. Results: Mean defect depths after application of powders A, B, C and D were significantly lower than with standard powder (A: 17.9 ± 10.9 µm, B: 48.2 ± 32.7 µm, C: 92.5 ± 57.9 µm, D: 33.9 ± 19.6 µm, NaHCO3: 163.1 ± 71.1 µm) (Kruskal,Wallis test). Among the experimental powders, D was transported most reliably in the air polishing unit and allowed complete removal of disclosed plaque as assessed on freshly extracted teeth. Conclusion: The novel air polishing powder D is of low abrasiveness to root cementum and dentin while being effective in removing dental plaque. Thus, it may be useful for safe and efficient plaque removal on exposed root surfaces. [source] The effects of subgingival calculus on the clinical outcomes of locally-delivered controlled-release doxycycline compared to scaling and root planingJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 2 2002Lonnie R. Johnson Abstract Background, aim: The effect of subgingival calculus on the clinical outcomes of the local delivery of antimicrobials is unknown. This study examines the clinical outcomes of treatment with locally delivered controlled-release doxycycline (DH) or scaling and root planing (SRP) in subsets of adult periodontitis patients with known baseline levels of subgingival calculus. Methods: The data examined were obtained from 393 patients who participated in 2 multi-center trials. All patients had baseline subgingival calculus levels assessed and were then treated at baseline and month 4 with either DH or SRP. Clinical attachment levels (CAL), pocket depth (PD) and bleeding on probing (BOP) were assessed at baseline and months 1, 2, 4, 5, 6, 8 and 9. Results: Treatment with either DH or SRP resulted in significant statistical and clinical improvements in CAL, PD and BOP. These clinical outcomes were equivalent regardless of the extent of subgingival calculus present at baseline. Conclusions: The results indicate that the primary clinical effects of these therapies are the result of a disruption and reduction of the subgingival plaque and not the effect of the removal of subgingival calculus and contaminated cementum. Zusammenfassung Hintergrund, Ziel: Der Effekt von subginvalem Zahnstein auf die klinischen Ergebnisse von lokal freigesetzten antimikrobiellen Mitteln ist unbekannt. Die Studie überprüfte die klinische Ergebnisse der Behandlung mit kontrolliert lokal freigesetztem Doxycyclin (DH) oder mit Wurzelreinigung und -glättung (SRP) bei einer Gruppe von Patienten mit Erwachsenen-Parodontitis mit bekanntem Ausmaß von subgingivalen Zahnstein zu Beginn der Studie. Methoden: Die zu überprüfenden Daten kamen von 393 Patienten, die an 2 multizentrischen Studien teilnahmen. Alle Patienten hatten zur Basis gemessene subgingivale Zahnsteinlevel, und sie wurden dann zur Basis und zum 4. Monat entweder mit DH oder SRP behandelt. Die klinischen Stützgewebeniveaus (CAL), die Sondierungstiefe (PD) und die Provokationsblutung (BOP) wurden zur Basis und zu den Monaten 1, 2, 4, 5, 6, 8 und 9 aufgezeichnet. Ergebnisse: Die Behandlung entweder mit DH oder SRP ergab statistisch signifikante und klinische Verbesserungen beim CAL, bei der PD und bei der BOP. Diese klinischen Ergebnisse waren unabhängig vom Ausmaß des subgingivalen Zahnsteins, der zur Basis vorhanden war, gleich. Schlussfolgerung: Die Ergebnisse zeigen, dass die primären klinischen Effekte von diesen Therapieformen das Resultat der Zerstörung und Reduktion der subgingivalen Plaque sind und nicht den Effekt von der Entfernung des subgingivalen Zahnsteins und kontaminierten Zementes darstellen. Résumé Origine, but: Les effets du tartre sous-gingival sur les comportements cliniques de l'application locale d'antimicrobiens sont inconnus. Cette étude examine le comportement clinique de traitement consistant en l'application locale de doxycycline à libération lente (DH) ou en un détartrage/surfaçage radiculaire seul (SRP) dans des groupes de patients atteints de parodontite de l'adulte avec des niveaux initiaux de tartre sous-gingival connus. Méthodes: Les données examinées sont obtenus chez 393 patients qui participèrent à 2 essais multi-centriques. Chez tous les patients, les niveaux de tartre sousgingivaux initiaux furent évalués et ils furent traités à 0 et à 4 mois avec soit DH, soit SRP. Les niveaux d'attache clinique (CAL), les profondeurs de poche (PD) et le saignement au sondage (BOP) furent évalués initialement et à 1, 2, 4, 5, 6, 8 et 9 mois. Résultats: Le traitement avec les 2 méthodes apportait des améliorations statistiquement significatives pour CAL, PD et BOP. Ces comportements cliniques étaient équivalents quel que fut l'importance du tartre sous-gingival initialement. Conclusions: Les résultats indiquent que les effets cliniques primaires de ces traitements sont le résultat de la réduction et de la désorganisation de la plaque sous-gingivale et non pas l'effet de l'élimination du tartre sous-gingival et du cément contaminé. [source] Generalized cervical root resorption associated with periodontal diseaseJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 11 2001Wouter Beertsen Abstract Background and description of case: The etiology and pathogenesis of generalized cervical root resorptions is not well understood. In the present report, a case of severe cervical root resorption involving 24 anterior and posterior teeth is presented. The lesions developed within a period of 2 years after the patient had changed to an acid-enriched diet. They extended far into the coronal dentin and were associated with gingival inflammation and crestal bone resorption. However, no generalized clinical attachment loss had occurred. Culturing of subgingival plaque revealed the presence of several putative periodontal pathogens among which Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis. Treatment consisted of mechanical debridement supported by systemic antibiotics (amoxycillin plus metronidazole) and dietary advice. Results: Within 1 year after the onset of treatment, all resorptive lesions had repaired by ingrowth of a radio-opaque mineralized tissue. The crestal areas showed radiological evidence of bone repair. 3 years after the onset of therapy, one premolar was extracted and examined histologically. It appeared that irregularly-shaped masses of woven bone-like tissue had invaded into the domain of the resorbed coronal dentin and were bordered by thin layers of acellular cementum. Conclusion: It is concluded that, in this patient, the cervical resorptions were likely the result of an osteoclastic response extending into the roots because the root-protective role of the junctional epithelium did not develop. We hypothesize that this was due to the combined effects of a periodontopathogenic microflora and a dietary confounding factor. Zusammenfassung Hintergrund und Beschreibung des Falls: Die Ätiologie und die Pathogenese der generalisierten Wurzelresorptionen ist nicht besonders bekannt. In der vorliegenden Fallpräsentation wird ein schwerer Fall von Wurzelresorption gezeigt, die 24 anteriore und posteriore Zähne einbezog. Die Läsionen entwickelten sich innerhalb einer Periode von 2 Jahren, nachdem der Patient zu einer Säure-angereicherten Diät gewechselt hatte. Die Läsionen dehnten sich in das koronale Dentin aus und waren mit gingivaler Entzündung und krestaler Knochenresorption verbunden. Jedoch wurde kein generalisierter Attachmentverlust beobachtet. Die Kultur der subgingivalen Plaque erbrachte das Vorhandensein von verschiedenen putativen parodontalen Pathogenen, unter ihnen Actinobacillus actinomycetemcomitans und Porphyromonas gingivalis. Die Behandlung bestand in der mechanischen Reinigung unterstützt mit systemischen Antibiotika (Amoxicillin und Metronidazol) und Diätanweisungen. Ergebnisse: Innerhalb eines Jahres nach dem Beginn der Therapie waren alle Resorptionsläsionen repariert durch das Einwachsen von röntgenopakem mineralisierten Gewebe. Die krestalen Regionen zeigten radiologisch nachgewiesene Knochenreparatur. 3 Jahre nach Therapiebeginn wurde ein Prämolar extrahiert und histologisch untersucht. Es schien, daß irreguläre geformte Massen von verflochtenem knochen-ähnlichen Gewebe in den Hauptteil des resorbierten koronalen Dentins hineingelangt sind und von dünnen Schichten azellulären Zementes begrenzt wurden. Zusammenfassung: Es wird geschlußfolgert, daß bei diesem Patient die zervikalen Resorptionen wahrscheinlich das Ergebnis einer osteoklastischen Reaktion waren, bis in die Wurzeln ausgedehnt, weil sich die wurzelschützende Rolle des Verbindungsepithels nich entwickelt hatte. Wir nehmen an, daß dies in der Folge eines kombinierten Effektes von parodontopathogenen Keimen und eines verwirrenden diätetischen Faktors geschah. Résumé Origine: L'étiologie et la pathogenèse des résorptions radiculaires cervicales généralisées ne sont pas suffisamment connues. Dans le rapport présent, un cas de résorption radiculaire cervicale sévère se rapportant à 24 dents antérieures et postérieures est présenté. Les lésions s'étaint développées durant les 2 années qui ont suivi le changement de régime alimentaire du patient vers un régime plus acide. Elles s'étendaient profondément dans la dentine coronaire et étaient associées à une inflammation gingivale et une résorption osseuse crestale. Cependant, aucune perte d'attache clinique généralisée n'est apparue. La culture de la plaque dentaire sous-gingivale a révélé la présence de plusieurs pathogènes parodontaux putatifs parmi lesquels l'Actinobaccilus actinomycetemcomitans et le Porphyromonas gingivalis. Le traitement a consisté en un nettoyage mécanique associéà l'utilisation d'antibiotiques par voie systémique (amoxycilline + métronidazole) et un conseil diététique. Résultats. Dans l'année qui a suivi ce traitement, toutes les lésions de résorption ont été guéries par la croissance d'un tissu minéralisé radio-opaque. Les zones crestales montraient une évidence radiologique de réparation osseuse. 3 ans après le démarrage de ce traitement, une prémolaire a été avulsée et examinée histologiquement. Il est apparu que des masses de formes irrégulières de tissus ressemblant à de l'os ouaté avaient envahi le domaine de dentine coronaire résorbé et étaient entourées par de fines couches de cément acellulaire. Conclusions: Chez ce patient, les résorptions cervicales étaient vraisemblablement dûes à une réponse ostéoclastique s'étendant dans les racines parce que le rôle de protection radiculaire de l'épithélium de jonction ne s'étaient pas développé. Cette situation était vraisemblablement dûe à des effets combinés de la microflore parodonto-pathogène et d'un facteur diététique. [source] Autocrine growth factors in human periodontal ligament cells cultured on enamel matrix derivativeJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 2 2001Staale P. Lyngstadaas Abstract Objective: Enamel extracellular matrix proteins in the form of the enamel matrix derivative EMDOGAIN® (EMD) have been successfully employed to mimic natural cementogenesis to restore fully functional periodontal ligament, cementum and alveolar bone in patients with severe periodontitis. When applied to denuded root surfaces EMD forms a matrix that locally facilitates regenerative responses in the adjacent periodontal tissues. The cellular mechanism(s), e.g. autocrine growth factors, extracellular matrix synthesis and cell growth, underlying PDL regeneration with EMD is however poorly investigated. Material and Methods: Human periodontal ligament (PDL) cells were cultured on EMD and monitored for cellular attachment rate, proliferation, DNA replication and metabolism. Furthermore, intracellular cyclic-AMP levels and autocrine production of selected growth factors were monitored by immunological assays. Controls included PDL and epithelial cells in parallel cultures. Results: PDL cell attachment rate, growth and metabolism were all significantly increased when EMD was present in cultures. Also, cells exposed to EMD showed increased intracellular cAMP signalling and autocrine production of TGF-,1, IL-6 and PDGF AB when compared to controls. Epithelial cells increased cAMP and PDGF AB secretion when EMD was present, but proliferation and growth were inhibited. Conclusion: Cultured PDL cells exposed to EMD increase attachment rate, growth rate and metabolism, and subsequently release several growth factors into the medium. The cellular interaction with EMD generates an intracellular cAMP signal, after which cells secrete TGF-,1, IL-6 and PDGF AB. Epithelial cell growth however, is inhibited by the same signal. This suggest that EMD favours mesenchymal cell growth over epithelium, and that autocrine growth factors released by PDL cells exposed to EMD contribute to periodontal healing and regeneration in a process mimicking natural root development. [source] Treatment of intrabony defects with guided tissue regeneration and enamel-matrix-proteinsJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 7 2000An experimental study in monkeys Abstract Background: Enamel matrix proteins (EMD) have recently been introduced in regenerative periodontal treatment. However, no histological data are yet available concerning the effect of treating intrabony periodontal defects with EMD, and no histological comparisons have been made comparing the result of treatment of intrabony defects with EMD with that of the treatment with guided tissue regeneration (GTR). Aim: Therefore, the aim of the present study was to evaluate histologically in monkeys the effect of treating intrabony defects with EMD, GTR or combined EMD and GTR. Method: Intrabony periodontal defects were produced surgically at the distal aspect of teeth 14, 11, 21, 24, 34, 31, 41 and 44 in 3 monkeys (Macaca fascicularis). In order to prevent spontaneous healing and to enhance plaque accumulation metal strips were placed into the defects. After 6 weeks the defects were exposed using a full-thickness flap procedure. The granulation tissue was removed and the root surfaces were debrided by means of hand instruments. Subsequently, the defects were treated using one of the following therapies: (i) GTR, (ii) EMD, or (iii) combination of EMD and GTR. The control defects were treated with coronally repositioned flaps. After 5 months, the animals were sacrificed and perfused with 10% buffered formalin for fixation. Specimens containing the defects and surrounding tissues were dissected free, decalcified in EDTA and embedded in paraffin. 8 ,m thick histological sections were cut and stained and subsequently examined under the light microscope. Results: In the control specimens, the healing was characterized by a long junctional epithelium and limited periodontal regeneration (i.e., new periodontal ligament, new cementum with inserting connective tissue fibers and new bone) in the bottom of the defect. The GTR-treated defects consistently presented periodontal regeneration when the membranes were not exposed whereas the sites treated only with EMD presented regeneration to a varying extent. The combined therapy did not seem to improve the results. Conclusion: It can be concluded that all 3 treatment modalities favor periodontal regeneration. [source] Concrescence of teeth: cemental union between the crown of an impacted tooth and the roots of an erupted toothJOURNAL OF ORAL PATHOLOGY & MEDICINE, Issue 1 2007Masaru Sugiyama Concrescence of teeth is a condition showing a union of adjacent teeth by only cementum. In all the previously reported cases, the union has been observed between the roots of the affected teeth. Here, we describe the first case that showed a concrescence of the crown of an impacted tooth and the roots of the erupted tooth. In addition, we discuss how this condition, especially the deposition of acellular cementum on the crown, occurred. [source] Clinical and SEM evaluations of three compomer systems in Class V carious lesionsJOURNAL OF ORAL REHABILITATION, Issue 8 2002A. I. Abdalla Summary The aim of this study was to evaluate the clinical performance of three compomer systems: Compoglass F, Dyract AP and F2000 in Class V carious lesions. In addition, some restorations were placed in teeth scheduled for extractions in order to evaluate the compomer/dentin interface with the scanning electron microscope (SEM). A total of 175 Class V carious lesions having the gingival margins extending into cementum were restored with the tested materials. Each restoration was clinically evaluated immediately after placement, after 1 year and after 2 years using the USPHS criteria. After 1 year no loss of restoration was recorded. No significant difference between the materials was observed for any evaluation category. After 2 years, one Compoglass and two Dyract restorations were lost. No loss of F2000 was reported. No significant difference was reported between the tested materials and between the 2-year data and baseline ones. A well-defined hybrid layer as well as resin tags was seen at the interface between the tested materials and vital dentin. [source] Multipotency of clonal cells derived from swine periodontal ligament and differential regulation by fibroblast growth factor and bone morphogenetic proteinJOURNAL OF PERIODONTAL RESEARCH, Issue 2 2009K. Shirai Background and Objective:, A blood supply is indispensable for the regeneration of damaged or lost periodontal ligament (PDL) tissue. Mesenchymal stem cell-like activity of cells derived from the PDL has been identified by their capacity to form fibrous and osseous tissue and cementum. However, it remains to be clarified whether the cells have an ability to build the capillary network of blood vessels. This study evaluated the potential of cells derived from the PDL to construct a blood vessel-like structure and examined how growth factors controlled the multipotency of the cells. Material and Methods:, The ability of a swine PDL fibroblast cell line, TesPDL3, to construct a blood vessel-like structure was evaluated on and in the self-assembling peptide scaffold, PuraMatrixTM. In addition, the ability of the cells to form mineralized nodules was evaluated on type I collagen-coated plastic plates. In some cases, fibroblast growth factor (FGF)-2 and bone morphogenetic protein (BMP)-2 were added to these cultures. The status of the expression of vascular and osteoblastic cell-specific markers in the cells was evaluated using reverse transcriptase-polymerase chain reaction (RT-PCR), Western blotting and immunofluorescence analyses. Results:, The TesPDL3 cells not only formed mineralized nodules in response to BMP-2 stimulation but also constructed tube-like structures in response to FGF-2 stimulation. Intriguingly, FGF-2 inhibited the BMP-2-induced formation of mineralized nodules. Conversely, BMP-2 inhibited the FGF-2-induced formation of tube-like structures. Conclusion:, Periodontal ligament fibroblasts have the potential to differentiate not only into osteoblastic but also into vascular cell lineages. The destiny of the cells was reciprocally regulated by BMP-2 and FGF-2. [source] The role of macrophages in the periodontal regeneration using Emdogain® gelJOURNAL OF PERIODONTAL RESEARCH, Issue 2 2008N. Fujishiro Background and Objective:, Emdogain® gel is clinically used as a periodontal regenerative material. However, the mechanism of the regeneration has not been completely elucidated. Although many studies have focused on the regenerative effect of Emdogain on connective tissue attachment and alveolar bone, the role of macrophages and the expression of growth factors remains unclear in the regeneration stimulated by Emdogain gel in vivo. The aim of this study was to investigate the effect of Emdogain gel on the expression of cytokines and growth factors by macrophages in vivo using a newly devised rat experimental periodontitis model. Material and Methods:, Rat experimental periodontitis was induced by elevating a full-thickness gingival flap and ligating silk threads around the first molars of the mandible. At 14 d after inducing experimental periodontitis, Emdogain gel or propylene glycol alginate was applied to the furcation area. The rats were killed 7 and 14 d after treatment with propylene glycol alginate or Emdogain gel. The expression of cytokines and growth factors, and the regeneration of periodontal tissue, were examined by histochemical and immunohistochemical methods. Results:, Fourteen days after the induction of periodontitis, the resorption of alveolar bone at furcation was observed and cytokines such as interleukin-1,, transforming growth factor-,1, receptor activator of nuclear factor-,B ligand, receptor activator of nuclear factor-,B and osteoprotegerin were found. In the Emdogain-treatment group, the formation of new acellular cementum and, more remarkably, recovery of the bone, were observed. The new bone formation ratio in the Emdogain treatment group was significantly higher than that of the propylene glycol alginate treatment group. Although the expression of cytokines such as interleukin-1,, transforming growth factor-,1, receptor activator of nuclear factor-,B ligand and receptor activator of nuclear factor-,B was very low, bone morphogenetic protein-2- and bone morphogenetic protein-4-expressing macrophages were observed close to the root, and bone morphogenetic protein-4-expressing macrophages were mainly observed close to the bone surface at the furcation in the Emdogain-treatment group. Conclusion:, These results suggest that wound-healing macrophages may express bone morphogenetic protein and play an important role in the regeneration of periodontal tissue at the furcation following the application of Emdogain gel. [source] Low-intensity pulsed ultrasound accelerates periodontal wound healing after flap surgeryJOURNAL OF PERIODONTAL RESEARCH, Issue 2 2008H. Ikai Background and Objective:, A study was conducted to evaluate the effects of low-intensity pulsed ultrasound on wound healing in periodontal tissues after mucoperiosteal flap surgery. Material and Methods:, Bony defects were surgically produced bilaterally at the mesial roots of the mandibular fourth premolars in four beagle dogs. The flaps were repositioned to cover the defects and sutured after scaling and planing of the root surface to remove cementum. The affected area in the experimental group was exposed to low-intensity pulsed ultrasound, daily for 20 min, for a period of 4 wk from postoperative day 1 using a probe, 13 mm in diameter. On the control side, no ultrasound was emitted from the probe placed contralaterally. After the experiment, tissue samples were dissected out and fixed in 10% formalin for histological and immunohistochemical analyses. Results:, The experimental group showed that the processes in regeneration of both cementum and mandibular bone were accelerated by low-intensity pulsed ultrasound compared with the control group. In addition, the expression level of heat shock protein 70 was higher in the gingival epithelial cells of the low-intensity pulsed ultrasound-treated tooth. Conclusion:, Our results suggest that osteoblasts, as well as cells in periodontal ligament and gingival epithelium, respond to mechanical stress loaded by low-intensity pulsed ultrasound, and that ultrasound accelerates periodontal wound healing and bone repair. [source] Prostanoids induce egr1 gene expression in cementoblastic OCCM cellsJOURNAL OF PERIODONTAL RESEARCH, Issue 5 2007L. Pham Background and Objective:, Prostanoids that activate protein kinase C signaling are potent anabolic stimulators of cementoblastic OCCM cells. Using cDNA subtractive hybridization, we identified early growth response gene-1 (egr1) as a prostanoid-induced gene. Egr1, a zinc-finger transcription factor expressed during tooth development, regulates cell growth and differentiation. We hypothesize that Egr1 may mediate part of the prostanoid-induced anabolic effect in cementoblasts. Our objective was to characterize prostanoid-induced egr1 gene expression in OCCM cells. Material and Methods:, Total RNA and proteins were assayed by northern blot and western immunoblot assays. Results:, Prostaglandin E2 -, prostaglandin F2, - and fluprostenol-induced egr1 mRNA levels peaked at 0.5 h and returned to baseline by 4 h. Prostaglandin F2, and fluprostenol more potently induced egr1 compared with prostaglandin E2. The phorbol ester, phorbol 12-myristate 13-acetate, which activates protein kinase C signaling, induced egr1 mRNA levels 66-fold over the control, whereas forskolin (a cAMP-protein kinase A activator) and ionomycin (a calcium activator) had no effect. Protein kinase C inhibition significantly inhibited prostaglandin E2 -, prostaglandin F2, - and fluprostenol-induced egr1 mRNA levels. Finally, prostanoids maximally induced Egr1 protein at 1 h. Conclusion:,egr1 is a primary response gene induced by prostaglandin E2, prostaglandin F2, and fluprostenol in OCCM cells through protein kinase C signaling, suggesting that Egr1 may be a key mediator of anabolic responses in cementoblasts. Cementum is vital for periodontal organ maintenance and regeneration. Periodontal ligament fibers (Sharpey's fibers) insert into bone and cementum, thereby supporting the tooth in the alveolus (1). If the periodontal organ is lost, its regeneration requires cementoblast differentiation in order to form new cementum for periodontal ligament fiber insertion. Early attempts to regenerate cementum have proven difficult and rarely generate sufficient tissue (2). A better understanding of the molecular and cellular regulators that promote cementoblast differentiation is critical for developing targeted periodontal regeneration. [source] Dental root resorption and repair: histology and histometry during physiological drift of rat molarsJOURNAL OF PERIODONTAL RESEARCH, Issue 5 2003Ryusei Kimura Objective:, The process of dental root resorption and subsequent cementum regeneration has not been sufficiently elucidated. This study aimed to examine the process of the root resorption and cementum regeneration during physiological tooth drift using a rat model, and to evaluate this experimental model. Methods:, Distal roots in mandibular first molars and the surrounding periodontal tissues were investigated with light and electron microscopy. The light microscopic approach included histochemical and histometric analyses utilizing the tartrate-resistant acid phosphatase (TRAP) reaction. Results:, Root resorption was observed in the distal side of the roots and was most active in 5- to 6-week-old rats, and gradually decreased hereafter. An increase in the number of TRAP-positive mononuclear cells, which seemed to be odontoclast precursor cells, preceded the increase in the number of odontoclasts. Root resorption was transient, and was followed by the new formation of acellular extrinsic fiber cementum accompanied with only a slight inflammation, and therefore classified as external surface resorption. Preparation for new cementum started adjacent to the resorption areas when root resorption was most active. Conclusions:, The root resorption during drift in rats is transient and followed by acellular extrinsic fiber cementum regeneration. Cellular kinetics suggested that odontoclast precursor cells are supplied as mononuclear cells from vascular spaces. [source] In vitro evaluation of Er:YAG laser scaling of subgingival calculus in comparison with ultrasonic scalingJOURNAL OF PERIODONTAL RESEARCH, Issue 5 2000A. Aoki The purpose of the present study was to evaluate the effectiveness of Er:YAG laser scaling and the morphological and histological changes of the laser-scaled root surface in comparison with the effectiveness and root surface changes produced by conventional ultrasonic scaling. Fifty-three periodontally involved human extracted teeth with a band of subgingival calculus were used. The teeth were divided randomly into 2 groups for laser scaling and ultrasonic scaling. Laser irradiation was performed at an energy output of 40 mJ/pulse and 10 pulses/s under water spray, with the probe tip contacted obliquely to the root surface. Ultrasonic scaling was performed at a clinically standard power setting. The time required for scaling, the scaled area and the temperature changes were determined using both methods of treatment. The features of the scaled surfaces were examined by histological and scanning electron microscope (s.e.m.) observations. The Er:YAG laser provided subgingival calculus removal on a level equivalent to that provided by the ultrasonic scaler, without major thermal elevation. Macroscopically, the laser-treated root surface was somewhat rougher than or similar to the ultrasonically scaled root. However, the efficiency of the laser scaling was lower than that of the ultrasonic scaling. In addition, histological examination revealed a thin deeply stained zone on the lased root surface, and s.e.m. analysis revealed a characteristic microroughness on the lased surface. The laser scaling provided a level of calculus removal that was similar to that provided by the ultrasonic scaling. However, the Er:YAG laser produced superficial, structural and thermal microchanges on the root cementum. [source] Feline odontoclastic resorptive lesions: unveiling the early lesionJOURNAL OF SMALL ANIMAL PRACTICE, Issue 11 2002C. Gorrel The purpose of this study was to increase understanding of the factors initiating feline odontoclastic resorptive lesions (FORLs). Fifty-six teeth (clinically and radiographically unaffected by ORLs) were harvested. Of these, 43 were from cats that had ORLs in other teeth (group A) and 13 were from cats with no clinical or radiographic evidence of ORLs in any teeth (group B). Twenty-six teeth in group A and one tooth in group B showed histological evidence of external root resorption (surface resorption and replacement resorption resulting in ankylosis). Some teeth in group B showed healed cementum resorption. It has previously been assumed that FORLs were similar to lesions associated with peripheral inflammatory root resorption, and were associated with periodontal disease. These histological findings suggest instead that a FORL is a non-inflammatory replacement resorption, resulting in ankylosis. The periodontal ligament of resorbing teeth lacked normal fibrous architecture, but was not inflamed. Resorption was not identified in cervical cementum. However, the histological appearance of the cervical cementum differed between the two groups. Several aetiopathogenetic explanatory models which arise from these observations are discussed. [source] | |||||||||||||||||||||||||