Selective cyclooxygenase-2 inhibition prevents bone resorption

The aim of the present work was to evaluate the effect of a selective cyclooxygenase-2 (COX-2) inhibitor (meloxicam) on the alveolar bone loss progression in experimentally induced periodontitis. Forty (40) Wistar rats were separated into 8 experimental groups (n = 5). Cotton ligatures were placed at the gingival margin level of the lower right first molars of some rats. Four groups were treated for 5 or 15 days with an oral dose of 15 mg/kg of body weight/day of the selective COX-2 inhibitor. The other groups were used as positive control (sham) or negative control in each experimental period. Standardized digital radiographs were taken after sacrifice at 5 and 15 days to measure the amount of bone loss at the mesial root surface of the first molar tooth in each rat. The treatment with meloxicam did not induce weight alteration or other visible systemic manifestations. One way analysis of variance (ANOVA) indicated that groups treated with meloxicam, after 5 days, had significantly less alveolar bone loss (p < 0.05) when compared with control groups. On the other hand, no significant differences in bone loss were observed after 15 days of treatment with meloxicam. These data provide evidence that systemic therapy with meloxicam can modify the progression of experimentally induced periodontitis in rats during the initial experimental period.     

Histological analysis of orthodontic root resorption in rats treated with the cyclooxygenase-2 (COX-2) inhibitor celecoxib

INTRODUCTION: It has been reported that anti-inflammatory drugs used for treatment of pain and discomfort related to orthodontic treatment could slow down tooth movement. However, the effect of these drugs on orthodontic root resorption is not well understood. OBJECTIVES: The aim of this study was to investigate whether the COX-2 inhibitor celecoxib offers some protection against orthodontically induced root resorption. DESIGN: Male Wistar rats were divided into four groups: Groups I and II were treated with saline and celecoxib (10 mg / kg), respectively for 3 days. Groups III and IV were treated with saline and celecoxib for 14 days. The upper left first molars of all rats were moved mesially for 14 days with 50 g of force. An area including the disto-apical aspect of the mesial root of the first molar was processed for histological and histochemical techniques with tartarate-resistant acid phosphatase (TRAP). OUTCOME MEASURE: The degree of root resorption was measured using an image analysis system with a grid-sheet superimposed in the root were resorption lacunae were counted. The number of TRAP-positive cells on the tooth root surface defined as odontoclasts were also evaluated. RESULTS: The results revealed that there were no significant differences in the degree of root resorption and in the number of odontoclasts on the root between the four groups studied. CONCLUSION: The short and long-term celecoxib administration did not suppress the root resorption in case of experimental orthodontic force application.     

The role of Actinomyces naeslundii peptidoglycan in alveolar bone resorption

Oral biofilms are composed of complex structured multi-species bacterial communities, which are the causative agents of periodontal diseases. The species Actinomyces naeslundii, formerly known as Actinomyces viscosus, have been isolated from oral cavities and gingival pockets. A. naeslundii is one of the early colonizers, and plays an important role in the formation of dental biofilms and induces alveolar bone destruction. Peptidoglycan (PGN), the major cell wall component of such gram-positive bacteria, is one of the virulence factors that causes host inflammation and induction of osteoclast formation. The effects of bacterial peptidoglycan on osteoclastic bone resorption was evaluated by measuring the area of bone resorption lacunae in osteoclast precursor cells stimulated with gram positive bacterial peptidoglycan. Tartrate-resistant acid phosphatase (TRAP)-positive multi-nuclei cells and the areas of PGN-induced pits were significantly greater in the infected cells than in controls. The expression of inflammatory cytokine genes (interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α) induced by PGN was examined using peritoneal macrophages isolated from BALB/c mice. The results showed that A. naeslundii PGN induced the expression of inflammatory cytokine genes. These results suggest that PGN of A. naeslundii is an important virulence factor in the development of periodontitis. In this review, we focused on the role of A. naeslundii PGN in alveolar bone resorption.     

The role of iNOS and PHOX in periapical bone resorption

Nitric oxide (NO) and reactive oxygen species (ROS) are key molecules in resistance to pathogens. Little is known about their role in pathogenesis of periapical lesions. To address this issue, we induced periapical lesions in mice lacking nitric oxide synthase (iNOS(-/-)) or phagocyte oxidase (PHOX(-/-)). iNOS(-/-) mice expressed higher levels of IL-1β, TNF-α, RANK, RANKL, and MCP-1 than C57BL/6 and PHOX(-/-). Apical thickening of the periodontal ligament was also greater in iNOS(-/-) compared with other groups. Interestingly, ROS production did not interfere in periapical lesion progression, but seemed to be essential for the appearance of multinucleated TRAP-positive cells. Thus, periapical lesion progression in iNOS(-/-) was associated with an imbalance of pro-inflammatory cytokines (IL-1β and TNF-α), bone-resorptive modulators (RANK and RANKL), and MCP-1. We conclude that NO, but not ROS, controls progression of bone resorption in a murine experimental model of apical periodontitis.     

Expression of cyclooxygenase-2 (COX-2) in an advanced metastasized hypopharyngeal carcinoma and cultured tumor cells

Purpose

The inducible enzyme cyclooxygenase-2 (COX-2) catalyzes PGE₂ production and plays an important role in the progression of many solid cancers. However, the role of COX-2 expression in cervical lymph node metastases of head and neck cancer has not been clarified yet.

Patient and methods

We comment on a male patient aged 53 who was admitted to an ENT-department with acute bleeding from an advanced hypopharyngeal carcinoma and a frontotemporal mass. Prior to palliative intended radiotherapy, the metastasis was resected. During the procedure, a small amount of tumor tissue was harvested for primary tumor cell culture.

Results

COX-2 overexpression was demonstrated in the primary tumor tissue, the metastasis, in the cultured tumor cells by standard immunohistochemistry, as well as cytochemistry.

Conclusions

A simultaneous expression of COX-2 in head and neck carcinoma was presented for the first time. Besides the prognostic impact in oral carcinogenesis, this COX-2 role of biomarker for aggressive head and neck squamous cell carcinomas should be further evaluated. Additionally, treatment of hypopharyngeal carcinomas with selective COX-2 inhibitors could be beneficial when administered in combination with radiochemotherapy.     

The role of lipopolysaccharide in infectious bone resorption of periapical lesion

BACKGROUND: The role of lipopolysaccharide (LPS) in periapical lesion-induced bone resorption was investigated. Polymyxin B (PMB), a specific inhibitor of LPS, was evaluated to treat the apical lesion. METHODS: Lipopolysaccharide isolated from two common endodontic pathogens, Fusobacterium nucleatum and Porphyromonas endodontalis, stimulated mouse macrophage (J774) to release interleukin-1alpha (IL-1 alpha) and tumor necrosis factor-alpha (TNF-alpha) in a time-dependent manner. RESULTS: Combination of LPS further enhanced the stimulation. PMB inhibited these effects significantly. LPS also stimulated matrix metalloproteinase-1 (MMP-1) gene expression in J774, whereas anti-IL-1 alpha and anti-TNF-alpha antibodies, as well as PMB, diminished this effect. A disease model of periapical lesion was established in Wistar rat. Administration of PMB reduced the extent of lesion-associated bone resorption by 76% to approximately 80%, and simultaneously reduced the numbers of MMP-1-producing macrophages. CONCLUSIONS: It is suggested that LPS released from the infected root canal triggers the synthesis of IL-1 alpha and TNF-alpha from macrophages. These pro-inflammatory cytokines up-regulate the production of MMP-1 by macrophages to promote periapical bone resorption.     

Bacterial bone resorption in noma (gangrenous stomatitis)

Abstract Bone resportion (gangrenous stomatitis) was found to be associated with extensive bacterial colonization of mandibular bone in three separate cases of noma. Light and electron microscopy revealed a heterogeneous bacterial population with a long, filamentous, Gram-positive organism predominantly in direct contact with the resorbing bone front. The bone was completely denuded and no osteoclastic activity was observed. The highly regular arrangement of the filamentous organism along the resorbing bone and the absence of osteoclastic activity suggested that bone resorption in noma is mediated by bacterial action.     

Selective COX-2 inhibitor reduces bone healing in bone defects

Anti-inflammatory agents have been reported to regulate bone healing. The aim of this study was to investigate the effect of a selective cyclooxygenase-2 inhibitor (meloxicam) on bone healing in calvarial defects in rats. Thirty-six adult male Wistar rats were included. After anesthesia, a linear incision was made through the skin of the scalp, a full-thickness flap was reflected and a 4 mm round defect was made with a trephine drill. The animals were randomly assigned to one of the following 4 treatment groups (9 animals each), including daily subcutaneous injections: A: saline solution for 15 days; B: saline solution for 45 days; C: 3 mg/kg of meloxicam for 15 days and D: 3 mg/kg of meloxicam for 45 days. The animals were sacrificed and the specimens, routinely processed. The bone filling was histometrically measured and statistical analysis, performed. Intergroup comparisons demonstrated that the meloxicam groups presented a significant reduction in bone healing when compared to their respective controls (group A, 44.5 +/- 5.75%, against group C, 57.5 +/- 7.25%, p < 0.05; group B, 40.25 +/- 13.75%, against group D, 52.25 +/- 17.25%). Within the limits of the present study, it can be concluded that selective cyclooxygenase-2 inhibitors may reduce bone healing in calvarial defects in rats after continuous administration.     

Calcium hydroxide and treatment of inflammatory inter-radicular bone resorption of non-vital deciduous molars

On non-vital deciduous molars, inter-radicular bone resorption is often an indication of extraction. The endodontic treatment of these teeth by means of zinc oxide-eugenol (ZOE) paste also showed its limits. To mitigate the deficiencies of this material, we suggested a preliminary treatment by means of calcium hydroxide (Ca(OH)2) for its anti-inflammatory and antiseptic properties as well as its ability to stimulate calcified tissues apposition or remineralisation. This study concerns 21 non-vital deciduous molars. X-rays excluded any lesion of the underlying permanent bony crypt (bone tissue) as well as any inflammation of the dental follicle. After preparation, root canals were filled by means of Pulpdent. An initial X-ray check was made 15 days and then every 3 months. After disappearance of the inflammatory resorption, root canal fillings were performed with ZOE paste. The remineralisation of the inter-radicular alveolar bone was observed for 14 deciduous molars, which were then filled using ZOE. The remineralisation period varies from 3 to 18 months depending on the scale of the lesion. Of the 7 failed treatments, 3 failed following downfall of the crown filling material, and 2 due to failure to keep appointments and late replacement of resorbed Ca(OH)2. On 2 teeth, the treatment did not stop the lesion forming. Calcium hydroxide (Ca(OH)2) give encouraging results in the treatment of inter-radicular alveolar bone resorption of non-vital deciduous tooth. Its fast resorption requires rigorous controls, frequent refills, and thus strong motivation on the part of the child and parents. It cannot, on any account, be considered as permanent filling material.     

Effects of locally-delivered human macrophage products and estrogen on murine inflammatory bone resorption

The objective of this study was to use an in vivo model of periodontitis (mouse calvaria) to quantify the effects of local release of secreted human macrophage products, 17beta-estradiol (E2), and proinflammatory lipopolysaccharide (LPS) on histologic bone resorption. Human THP-1 monocytes (106) were converted to macrophage phenotype by 500 ng/ml phorbol 12-myristate- 13-acetate (PMA) and treated as follows: no stimulation or Escherichia coli LPS (10 microg/ml) alone or in combination with a physiologic dose of E2 (100 pg/ml) for 24 h in RPMI/10% FBS, washed extensively, then incubated for 24 h in serum-free media. Supernatant products were concentrated and incorporated into a 4% (w/v) methylcellulose gel. Separate gels were incorporated with the following: LPS (500 microg/animal) alone, high dose of E2 (10 ng/animal) alone, a combination of LPS + E2, or gel only (controls). Loaded or control gels were placed into a polylactic acid occlusive dome, inserted subcutaneously over the calvaria of mature ovariectomized ICR Swiss mice (8 mice x 7 groups x 2 times [5/14 days] = 112 animals), then calvaria were evaluated histologically. Macrophage stimulation with LPS alone, but not LPS in combination with E2, produced supernatants which upregulated osteoclast numbers in the suture area compared to gel controls at 5 days (p = 0.009). The addition of LPS directly to the local delivery gels significantly upregulated osteoclasts in endosteal surfaces compared to gel controls at 5 days (p = 0.024) and at 14 days (p = 0.025). The addition of E2 to LPS down-regulated resorption to a level not different from gel controls at 14 days. This in vivo model appears effective in studying inflammatory bone resorption, which may be inhibited by E2 directly or through its influence on secreted macrophage products.     

The role of RANKL and MMP‐9 in the bone resorption caused by ameloblastoma

J Oral Pathol Med (2010) 39 : 592–598 Background: Ameloblastoma, a common odontogenic tumor located in jaws, generally leads to severe damage to patient’s complexion and masticatory function. To expand in jaws, ameloblastoma must have a mechanism of resorbing the surrounding bone. Our objective was to explore the bone‐resorption mechanism of ameloblastoma by observing the role of Receptor activator of nuclear factor kappa B ligand (RANKL) and matrix metalloproteinase‐9 (MMP‐9) in the bone‐resorption process. Methods: In the study, the expression of RANKL and MMP‐9 in ameloblastoma was detected using immunohistochemistry (IHC) and RT‐PCR. Then, co‐culture system of ameloblastoma cells and bone marrow cells from neonatal rabbit was erected to observe the potential of ameloblastoma cells to induce osteoclastogenesis. Finally, the induced osteoclasts were used for in vitro bone‐resorption assay. In the co‐culture system and the bone‐resorption assay, the selective inhibitor of RANKL and MMP‐9, osteoprotegerin (OPG) and tissue inhibitor of metalloproteinase‐1 (TIMP‐1) were, respectively, used for observing the role of RANKL and MMP‐9. Results: The expression of RANKL and MMP‐9 in ameloblastoma was confirmed. Ameloblastoma cells were found to induce bone marrow cells from neonatal rabbit differentiate into osteoclasts with bone‐resorption activity. In addition, OPG was found to, respectively, have markedly inhibitory effect on osteoclastogenesis (P < 0.01), and slightly inhibitory action on bone resorption (P < 0.05). Conclusions: Ameloblastoma cells had the potential to induce osteoclastogenesis. Moreover, RANKL played an essential role in the in vitro osteoclast formation and bone resorption induced by ameloblastoma cells.     

Celecoxib and rofecoxib. The role of COX-2 inhibitors in dental practice

BACKGROUND: In recent years, dental practitioners have relied on ibuprofen and other nonsteroidal anti-inflammatory drugs, or NSAIDs--such as naproxen, diflunisal and ketoprofen--to manage acute and chronic orofacial pain. Two NSAIDs that recently came on the market, celecoxib and rofecoxib, have been developed to limit the adverse effects seen after chronic use of NSAIDs. LITERATURE REVIEWED: The authors have summarized all available publications describing the human pharmacokinetics, clinical pharmacology and known adverse effects of these new specific cyclooxygenase-2, or COX-2, inhibitors. CONCLUSIONS: Although peripherally acting analgesics are remarkably effective, chronic administration of nonselective COX inhibitors has been associated with gastrointestinal ulceration and prolonged bleeding. The authors present the distinctive mechanism of action for these new COX-2 inhibitors, compare their relative anti-inflammatory and analgesic properties and describe their safety profile. They also summarize indications, contraindications and dosing recommendations. CLINICAL IMPLICATIONS: Celecoxib and rofecoxib are valuable dental therapeutic agents for the management of inflammatory joint disorders and associated chronic orofacial pain. Additionally, rofecoxib, with its more rapid onset, may be useful in treating selected cases of acute postsurgical pain.     

白细胞介素—1刺激新生小鼠骨吸收培养液中PGE2含量的测定

利用新生纯系KM小鼠颅盖骨体外培养模型，通过放免法检测培养液中PGE2含量的变化，研究白细胞介素一1（IL-1）刺激和介导骨吸收效应中PGE2的作用和相互关系以及消炎痛对此效应的作用。结果表明：在培养体系中加入IL-1后，可导致PGE2含量的显著增加（P＜0．01）．同时加入消炎痛后这一增加趋势受到明显抑制（P＜0．01）。提示IL-1的骨吸收作用可能有内源性前列腺素的参与．IL-I是通过刺激局部细胞合成PGE2转而介导破骨细胞吸收骨．     

A role for TNF in bone resorption of deciduous molars in human beings.

In this study, tumor necrosis-alpha was sampled from the gingival crevice of human deciduous molars; this was compared with values measured from the crevice of those deciduous molars missing a permanent successor, and from the crevice of deciduous ankylosed molars. Tumor necrosis-alpha was harvested from the gingival crevice with magnetic microspheres coated with tumor necrosis-alpha antibodies. The amount of bead-bound tumor necrosis-alpha was quantified with the use of an enzyme-linked immunosorbent assay. One hundred seven sites (from 41 patients) were sampled; for each patient, the normal value was compared with either the molars missing a permanent successor or ankylosed value. The tumor necrosis-alpha levels were 1.6 times higher from the crevice of ankylosed deciduous molars when compared with normal deciduous molars and 2.6 times higher from the crevice of sites with a molar missing a permanent successor. The mean and standard error mean distribution of tumor necrosis-alpha expressed as picograms was: normal molars 91 pg (standard error mean +/- 20), ankylosed molars 150 pg (standard error mean +/- 31), and missing permanent successor 236 pg (standard error mean +/- 67). Analysis of variance showed the difference among the 3 means was close to attaining significant difference (F [2.104] = 2.7905, P =.066). Multiple comparison procedures indicated that the mean for molars missing a permanent successor and the normal groups were significantly different, P =.05. The results of this study suggest tumor necrosis-alpha values are elevated in the gingival crevice of deciduous molars with ankylosis and where the permanent tooth bud is congenitally missing.     

自然牙与种植联合修复体基牙的骨吸收临床观察

目的 探讨自然牙与种植体联合固位修复中自然牙根与种植体周围骨吸收情况.方法 选取10例自然牙与种植体联合修复患者作为研究组,分别选择15例单种植体修复和15例单冠修复固定义齿作为对照组.种植体均于术后3个月行冠部修复体修复.分别于术后第1、6、12、18个月进行X线检查,对所有自然牙及种植体的周围骨吸收情况进行测量.结果 在18个月时自然牙与种植牙联合固位修复中组,自然牙根远中骨高度变化大于单冠组自然牙根(P＜0.05),其余各组均无统计学差异.联合修复的固位体及对照单颗天然牙和单颗种植体修复体均未出现修复体松动、折断.结论 自然牙与种植牙联合固位修复在短期内自然牙及种植体的周围骨吸收较少,可以达到临床应用要求.     

The effect of a selective cyclooxygenase-2 inhibitor (celecoxib) on chronic periodontitis

BACKGROUND: Non-steroidal anti-inflammatory agents inhibit the production of cyclooxygenase (COX) products and can attenuate bone loss. In this double-masked, placebo-controlled, randomized clinical trial, the efficacy of celecoxib (COX-2 inhibitor) was evaluated in conjunction with scaling and root planing (SRP) in subjects with chronic periodontitis (CP). METHODS: A total of 131 subjects were randomized to receive SRP and either celecoxib (200 mg) or placebo every day for 6 months. Clinical outcomes were assessed every 3 months for 12 months as mean changes from baseline. Primary efficacy parameters included clinical attachment level (CAL) and probing depth (PD). Secondary outcomes included percentages of tooth sites with CAL loss or gain > or =2 mm, changes in bleeding on probing (BOP), plaque index, and mobility. Prior to analysis, tooth sites were grouped based on baseline PD as shallow (1 to 3 mm), moderate (4 to 6 mm), or deep (> or =7 mm). RESULTS: Mean PD reduction and CAL gain were greater in the celecoxib group, primarily in moderate and deep sites, throughout the study (PD: 3.84 mm versus 2.06 mm, P <0.001; CAL: 3.74 mm versus 1.43 mm, P <0.0001 for deep sites at 12 months). The celecoxib group also exhibited a greater percentage of sites with > or =2 mm CAL gain and fewer sites with > or =2 mm CAL loss. Both groups showed improved plaque control and BOP scores. Demographic, social, and behavioral factors did not affect treatment outcomes. CONCLUSIONS: Celecoxib can be an effective adjunctive treatment to SRP to reduce progressive attachment loss in subjects with CP. Its beneficiary effect persisted even at 6 months postadministration. However, given the increased cardiovascular risks associated with the use of this drug, close patient supervision and strict adherence to dosage and administration guidelines established by the Unites States Food and Drug Administration are of paramount importance.