The Effects of NF-kB Inhibition with p65-TMD-Linked PTD on Inflammatory Responses at Peri-implantitis Sites

The objective of this study was to find out if suppression of NF-kB complex function by p65-TMD-linked PTD could reduce host inflammation and bone resorption at peri-implantitis sites in rats. Twenty-one male 5-week-old SD rats were divided into three groups: untreated control group (A), silk-induced peri-implantitis group (B), and nt (nucleus transducible)-p65-TMD-treated, silk-induced peri-implantitis group (C). Implant sulcus of a rat in group C were divided into two groups, namely group Cp and Cb. Palatal implant sulcus where nt-p65-TMD solution was applied with an insulin syringe were assigned to group Cp. Buccal implant sulcus without topical nt-p65-TMD application were assigned to group Cb. H&E staining, TRAP staining, and immunohistological staining were done. The crestal bone levels of group A were significantly higher than those of group B at p<0.01. The crestal bone levels of group Cp were significantly higher than those of group Cb at p<0.05. H-E staining showed increased apical migration of junctional epithelium and inflammatory cells in group Cb. TRAP staining revealed more multinucleated osteoclasts in group Cb. As for immunohistological staining, group Cb showed many IL-6-positive cells while group Cp had none. In this study, p65-TMD-linked PTD inhibited NF-kB functions and reduced inflammation and bone resorption at peri-implantitis sites in rats.

The Dual Effects of Reactive Oxygen Species on the Mandibular Alveolar Bone Formation in SOD1 Knockout Mice: Promotion or Inhibition

The status of reactive oxygen species (ROS) correlates closely with the normal development of the oral and maxillofacial tissues. Oxidative stress caused by ROS accumulation not only affects the development of enamel and dentin but also causes pathological changes in periodontal tissues (periodontal ligament and alveolar bone) that surround the root of the tooth. Although previous studies have shown that ROS accumulation plays a pathologic role in some oral and maxillofacial tissues, the effects of ROS on alveolar bone development remain unclear. In this study, we focused on mandibular alveolar bone development of mice deficient in superoxide dismutase1 (SOD1). Analyses were performed using microcomputerized tomography (micro-CT), TRAP staining, immunohistochemical (IHC) staining, and enzyme-linked immunosorbent assay (ELISA). We found for the first time that slightly higher ROS in mandibular alveolar bone of SOD1(-/-) mice at early ages (2-4 months) caused a distinct enlargement in bone size and increased bone volume fraction (BV/TV), trabecular thickness (Tb.Th), and expression of alkaline phosphatase (ALP), Runt-related transcription factor 2 (Runx2), and osteopontin (OPN). With ROS accumulation to oxidative stress level, increased trabecular bone separation (Tb.Sp) and decreased expression of ALP, Runx2, and OPN were found in SOD1(-/-) mice at 6 months. Additionally, dosing with N-acetylcysteine (NAC) effectively mitigated bone loss and normalized expression of ALP, Runx2, and OPN. These results indicate that redox imbalance caused by SOD1 deficiency has dual effects (promotion or inhibition) on mandibular alveolar bone development, which is closely related to the concentration of ROS and the stage of growth. We present a valuable model here for investigating the effects of ROS on mandibular alveolar bone formation and highlight important roles of ROS in regulating tissue development and pathological states, illustrating the complexity of the redox signal.

Reversible dysphagia due to gabapentin-induced jaw myoclonus

Supplemental Digital Content is available in the text

A Novel Silicon Device for the Packing of Cutaneous Abscesses

BACKGROUND

Superficial skin abscesses are commonly encountered in emergency medicine practice. Standard treatment includes incision, drainage, and often packing with a gauze strip. The packing component of the procedure has several negative potential outcomes, is painful, and necessitates a return visit for removal.

DISCUSSION

Here we report the first case in which a novel silicon packing device was utilized. The patient presented with a facial abscess, which was incised and drained. The novel device was inserted, and removed by the patient independently, without complication. Both patient and provider reported satisfaction with the novel procedure, and noted low pain scores.

CONCLUSIONS

This device has the potential to replace traditional packing, and will require further study through a controlled trial to assess for safety and efficacy.

Remodeling the neck and the lower jaw with dehoxycholate injections

Nonsurgical cosmetic facial procedures have gained popularity in recent decades. These procedures are commonly referred to as facial rejuvenation, and only a few are performed in the neck region. Herein, the authors describe their experience with off-label use of deoxycholic acid (DC) injections on 18 patients for remodeling of the neck and lower jaw. The injection protocol was personalized for each patient, and lidocaine was always premixed with the DC. After the initial injection visit, at least 3 months passed before further injections were considered. All documented side effects, including swelling and dysesthesia, resolved spontaneously. All patients received follow-up for at least 3 months, and only 2 patients required a second session of injections. By personalizing the injection protocol for each patient, good outcomes were achieved, including aesthetic enhancement of the shape and contour of the jaw and neck. Although the study is limited by the relatively small sample size, the results are promising and warrant additional investigations.

Systemic administration of the dietary constituent resveratrol inhibits the nociceptive jaw-opening reflex in rats via the endogenous opioid system

The aim of the present study was to investigate whether, under in vivo conditions, systemic administration of resveratrol could attenuate the rat nociceptive jaw-opening reflex (JOR) via the endogenous opioid system. The JOR evoked by electrical stimulation of the tongue was recorded as digastric muscle electromyograms (dEMG) in pentobarbital-anesthetized rats. The amplitude of the dEMG increased significantly in proportion to the intensity of electrical stimulation (from 1× to 5 × threshold for the JOR). dEMG amplitude in response to 3× threshold electrical stimulation of the tongue was dose-dependently inhibited by intravenous administration of resveratrol (0.5-2mg/kg). Maximum inhibition of dEMG amplitude was seen within approximately 10min. These inhibitory effects were reversible, with dEMG responses returning to control levels after approximately 20min. Pretreatment of rats with naloxone resulted in significant, dose-dependent attenuation of the inhibitory effects of resveratrol on dEMG amplitude compared with control. These findings suggest that resveratrol inhibits the nociceptive JOR via the endogenous opioid system. Further, the findings of the present study strongly support the idea that resveratrol, which is not known to have any toxic side effects, combined with an opioid could be a potential therapeutic agent for the prevention of acute trigeminal nociception.

The starting point for bisphosphonate-related osteonecrosis of the jaw: Alveolar bone or oral mucosa? A randomized, controlled experimental study

OBJECTIVE

Although over a decade has passed since first introduction of BRONJ, the exact pathophysiology of this disease is still unclear. The present experimental study aimed to determine whether the oral mucosa or alveolar bone serves as the starting point for BRONJ development.

SUBJECTS AND METHODS

Sixty male Wistar rats were randomly assigned into study and control groups (each, n = 30), and received intraperitoneal injection of 0.06 mg/kg zoledronate and saline, respectively, once a week for 12 weeks. At the end of the week 4 of the experiment, all 60 rats underwent unilateral mandibular first molar extraction. A 4 mm defect was made in the contralateral canine alveolar mucosa. At the end of the experiment, rats were sacrificed, and the three areas of interest including extraction, soft tissue defect, and the non-intervention (canine area on the same side of extraction) sites were assessed clinically for presence of bone exposure/fistula, and histologically for status of bone remodeling (only at extraction site) and osteonecrosis.

RESULTS

In the study group, the frequency of bone exposure/fistula was 80%, 0%, and 0%; and the rate of histological bone necrosis was 83.3%, 20%, and 0%; at the extraction, soft tissue defect, and non-intervention sites, respectively. No clinical and histological sign of bone necrosis was found in the control group. Normal bone remodeling was observed in 0% and 100% of the extraction sockets in the study and control groups, respectively.

CONCLUSION

Injury to alveolar bone was a stronger trigger for BRONJ development compared to oral mucosal damages.

Dioxin disrupts cranial cartilage and dermal bone development in zebrafish larvae

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD or dioxin) disrupts craniofacial development in zebrafish larvae. However, the cellular changes responsible for the decreased jaw size remain poorly understood. We show that smaller jaw size is due to a decrease in both the size and number of chondrocytes in the developing craniofacial cartilages. TCDD was found to decrease ossification of osteoblasts in the perichondrium of craniofacial cartilages. We also discovered that TCDD caused clefting of the parasphenoid, an effect with similarity to TCDD-induced cleft palate in mice. Thus, dermal and perichondrial bone development of the craniofacial skeleton are clearly disrupted by TCDD exposure in the zebrafish larvae. This dysmorphic response of the zebrafish craniofacial skeleton after exposure to TCDD is consistent with findings demonstrating disruption of axial bone development in medaka and repression of sox9b in zebrafish.

Biocompatibility of pure and mixed hydroxyapatite and α-tricalcium phosphate implanted in rabbit bone

Calcium phosphates and hydroxyapatite, in particular, are used as substitute materials in experimental implantology. These materials are primarily used in hard tissue replacement because their chemical and crystallographic characteristics are considered to be similar to the mineral content, osteoconductivity and bioactivity of normal bone. Cytokines, such as interleukin (IL)-1, IL-6, IL-8, IL-10 and antimicrobial protein β-defensin-2 (βDef-2), are used as biomarkers of non-specific reactogenicity. Other biomarkers, including bone morphogenetic protein-2/4 (BMP-2/4), bone regeneration protein osteoprotegerin (OPG), bone matrix protein osteopontin (OP) and osteocalcin (OC), are regarded as specific factors of reactogenicity in bone substitution. The aim of our study was to assess the changes in the distribution and expression of the aforementioned proteins in the lower jaws of rabbits following implantation with pure hydroxyapatite (HAP), α-tricalcium phosphate (α-TCP) or a mix of the two (HAP/α-TCP) manufactured under different temperatures. Our results reveal osteoblast proliferation and regions of granulation tissue formation between biomaterial granules close to the original implantation site, but in the control tissue these changes were less noticeable. Our study showed low variability in the distribution of βDef-2, OPG and all of the tested interleukins and these proteins were less expressed than BMP2/4, OP and OC. But across all experiments, no statistically significant difference in mean βDef-2, IL-1, IL-6, IL-8, IL-10, OP, OC, BMP-2/4 and OPG expression in osteocytes was detected between experimental and control groups. We concluded that pure and mixed HAP and α-TCP sintered at different temperatures do not affect the production of cytokines and bone-specific proteins; regions with osteoblast proliferation and low levels of anti-inflammatory cytokines IL-6 and IL-10 indicates better biocompatibility for HAP/α-TCP and α-TCP-2 biomaterials and the moderate number of BMP-2/4- and a prevalence of OC- and OP-positive osteocytes in experimental tissues implanted with HAP at 3 months after implantation indicates potential bone regeneration stimulated by pure HAP.

Cardiac toxicity by sublethal 2,3,7,8-tetrachlorodibenzo-p-dioxin correlates with its anti-proliferation effect on cardiomyocytes in zebrafish embryos

The cardiac toxicity of zebrafish embryos in response to the lethal dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been well characterized. Dioxin contamination levels in nature are usually lower, however, and sublethal TCDD toxicity is less investigated. The present study found that the nonlethal doses of TCDD for 72-h-postfertilization (hpf) zebrafish embryos were 25 pg/mL and lower. For the present study, sublethal TCDD concentrations of 10 pg/mL and 25 pg/mL were selected, and their toxicity was then characterized. The results showed that embryos still exhibited acute and subchronic cardiac toxicity at these 2 dosages. The stroke volume and cardiac output of these embryos significantly declined early until 8 d postexposure. Embryos' heart size became smaller, and the hearts contained fewer cardiomyocytes per heart, with decreased cardiomyocyte proliferation. Apoptosis was not detected either in the TCDD-treated or the control hearts. Real-time polymerase chain reaction (PCR) revealed that the transcription of a battery of cell-cycle-related genes was suppressed within the sublethal TCDD-treated heart. In contrast, embryonic jaw development seemed not to be affected. The present study suggests that dioxin contamination, even at lower levels, might lead to cardiac toxicity in fish embryos. Such cardiac toxicity presents as disrupted normal heart function, originating from the anti-proliferative effect of sublethal TCDD on cardiomyocytes.

Prospective, mono-institutional study of the impact of a systematic prevention program on incidence and outcome of osteonecrosis of the jaw in patients treated with bisphosphonates for bone metastases

The aim of our study was to investigate the occurrence of osteonecrosis of the jaw (ONJ) after implementation of dental preventive measures before starting bisphosphonates (BPs) therapy and during treatment. All consecutive patients with bone lesions eligible for BPs treatment were prospectively evaluated. Before starting BPs, each patient underwent a strict dental preventive program with a specialized odontoiatric team. The odontoiatric evaluation identified patients with oral pathologies or inadequate oral hygiene and provided a dental preventive treatment. From April 2007 to April 2012, 254 patients were enrolled. After excluding patients due to previous BPs treatment, 212 patients with a mean age of 74 years (range 37-95) were included. On average, patients received 9.7 treatment cycles (range 1-48). No ONJ was recorded (0.0 %; 95 % confidence interval [CI] 0.0-1.4). Comparing this risk with that observed in a previous cohort who did not receive dental prevention (16/186, 8.6 %; 95 % CI 4.2-15.3 %), we observed clear efficacy in preventing ONJ (relative risk reduction: 100 %, 95 % CI 86-100 %, P < 0.0001). We developed a strict three-step prevention program that is able to decrease ONJ incidence and the need for destructive surgery with permanent sequelae. We demonstrated that ONJ could be effectively prevented. We recommend a mandatory preventive program involving a multidisciplinary team for all patients starting BPs.

Implications of high-dosage bisphosphonate treatment on bone tissue in the jaw and knee joint

Bisphosphonates are bone antiresorptive agents traditionally used on a relatively large scale for treatment of bone metabolic diseases and on a smaller scale for bone metastasis treatment. A study on the effects of bisphosphonate treatment on healthy instead of diseased animals will give more insight into the basic mechanisms of bisphosphonates and their effects on different bone sites. We aimed to assess the effect of BP on the mouse knee and jaw joint. Three-month old female C57BL/6 mice were used (twenty-four and eighteen control and experimental group, respectively). At baseline and after treatment with zoledronic acid (ZA) for one, three or six months, we combined bone assessment via µCT and additional histology. Our results showed that, in the knee joint, ZA treatment increased TMD, bone volume, trabecular thickness but did not influence cortical thickness. In both control and ZA group, a higher trabecular TMD compared to cortical TMD was seen. Unseen in the knee joint, ZA treatment in the jaw joint resulted in bone-site specific changes in mineralization; a significant time-dependent higher TMD was evident in the subchondral bone compared to the most distal region of the condyle. MicroCT images revealed the presence of mineral in this region and histology showed that this region did not contain mature bone tissue but cartilage-like tissue. Our data indicate the possibility of site-specific negative side effects, i.e., disturbing normal mandibular development under the influence of bisphosphonate therapy.

Modulation of estrogen causes disruption of craniofacial chondrogenesis in Danio rerio

Estrogen is a steroid hormone that is ubiquitous in vertebrates, but its role in cartilage formation has not been extensively studied. Abnormalities of craniofacial cartilage and bone account for a large portion of birth defects in the United States. Zebrafish (Danio rerio) have been used as models of human disease, and their transparency in the embryonic period affords additional advantages in studying craniofacial development. In this study, zebrafish embryos were treated with 17-β estradiol (E2) or with an aromatase inhibitor and observed for defects in craniofacial cartilage. Concentrations of E2 greater than 2μM caused major disruptions in cartilage formation. Concentrations below 2μM caused subtle changed in cartilage morphology that were only revealed by measurement. The angles formed by cartilage elements in fish treated with 1.5 and 2μM E2 were increasingly wide, while the length of the primary anterior-posterior cartilage element in these fish decreased significantly from controls. These treatments resulted in fish with shorter, flatter faces as estrogen concentration increased. Inhibition of aromatase activity also resulted in similar craniofacial disruption indicating that careful control of estrogen signaling is required for appropriate development. Further investigation of the phenomena described in this study could lead to a better understanding of the etiology of craniofacial birth defects and endocrine disruption of cartilage formation.

The phosphorous necrosis of the jaws and what can we learn from the past: a comparison of "phossy" and "bisphossy" jaw

INTRODUCTION

The osteopathology of the jaws associated with bone resorption inhibitors is a current topic that engages a variety of clinical specialists. This has increased after the approval of denosumab for treatment of osteoporosis and skeletal-related events in patients with solid malignancy. Early after the first publications, there is a possible connection between phosphorous necrosis of the jaws, a dreadful industrial disease mentioned, and bisphosphonate-induced pathology. The nineteenth century was the prime time for phosphorus necrosis of match factory workers.

RESULTS

This occurrence provides an interesting insight into the medical and surgical profession in the nineteenth century. There are striking parallels and repetition of current and old ideas in the approach to this "new disease." There are similar examples in case descriptions when compared with today's patients of bisphosphonate-related osteonecrosis of the jaws (BRONJ).

DISCUSSION

Phosphorus necrosis was first described in Austria. Soon after this, surgeons in German-speaking countries including well-known clinicians Wegner (1872) and von Schulthess-Rechberg (1879) pioneered the analysis, preventative measures, and treatment of this disease. The tendency at this time was to approach BRONJ as a "special kind of osteomyelitis" in pretreated and metabolically different bone. Not only the treatment strategy to wait until sequestrum formation with subsequent removal and preventative measures but also the idea of focusing on the periosteum as the triggering anatomical structure may have been adopted from specialists in the nineteenth century. Therefore, phosphorous necrosis of the jaw is an excellent example of "learning from the past."

Pseudoepitheliomatous hyperplasia associated with bisphosphonate-related osteonecrosis of the jaw

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a well-characterized oral complication of systemic therapy with bisphosphonates. Pseudoepitheliomatous hyperplasia was observed in some of the lesions. Because podoplanin expression has been linked to malignant lesions of the oral mucosa, we aimed to investigate podoplanin expression in the pseudoepitheliomatous hyperplasia. We analyzed archival paraffin- and plastic-embedded specimens from BRONJ using both conventional and immunohistochemical (AE1/AE3, D2-40) staining methods. Eleven out of seventeen BRONJ cases showed pseudoepitheliomatous hyperplasia. All these cases were positive for AE1/AE3 and pseudoepitheliomatous hyperplasia displayed a strong basal and parabasal reaction against podoplanin. The podoplanin expression in pseudoepitheliomatous hyperplasia in BRONJ specimens should not be considered a sign of malignancy. We discuss the current and possible future roles of surgical pathologists in diagnosing morphological changes associated with the development and therapy of BRONJ lesions.

Bisphosphonate-related osteonecrosis of the jaws: legal liability from the perspective of the prescribing physician

Recently, it has been reported that patients administered with bisphosphonates (BP), in particular cancer patients receiving intravenous amino-bisphosphonates, as well as patients taking oral BP for prevention/treatment of diseases of altered bone turnover, may be affected by a significant adverse reaction-BP-related osteonecrosis of the jaws (BRONJ). This condition may cause high morbidity and detriment of quality of life. Its treatment is complex and often unsatisfactory, and prevention strategies may have limited effectiveness, if any; thus, BRONJ may become a source of litigation in the near future. Although most cases seem to be triggered by invasive dental procedures and oral health care providers are more exposed to malpractice claims and legal actions pursuant to BRONJ, the attribution of liability requires caution. In fact, types of possible negligence claims against oral health care providers have already been highlighted. However, according to the medico-legal methodology, since BRONJ is an adverse reaction to BP administration, the attribution of liability, if any, requires a comprehensive consideration of the chain of events and figures acting before, and potentially related to BRONJ. The physician prescribing BP at the start of this chain has specific duties which we are going to address, and breaching these duties may set the stage for potential liability claims.

Pathophysiology of osteonecrosis of the jaw in patients treated with bisphosphonate

Apart from the well-known mechanism of bisphosphonates' cellular effect, embryonic development and the specific features of alveolar bone homeostasis have been discussed. The unique ethiopathogenic mechanism which relates osteonecrosis of the jaw and bisphosphonates treatment has not been explained. The emphasis lies on the toxicological effects of bisphosphonates on the physiology of the alveolar bone and on the lasting effect of tooth extraction followed by an infection of the extraction wound and consequent progression into deeper layers of osseous tissue. Epithelial infection includes microbiological findings of Actinomyces species. The risk is pronounced in oncological patients treated with bisphosphonates intravenously in relatively large doses and during a longer period of time, especially with highly potent nitrogen-containing bisphosphonates pamidronate and zoledronate. This review of bisphosphonate-related osteonecrosis of the jaw stresses the significance of some other risk factors (corticosteroids, chemotherapy, tumour tissue etc.) of necrosis development--more precisely of osteomyelitis of the jaw if the microbiological component of the diseases has been taken into account, while the role of the bisphosphonates becomes minor. There is no gold standard for the treatment of jaw osteonecrosis; rather, palliative and minimally invasive treatment is applied, without subsequent oral surgical interventions. Since there is a significant risk of jaw osteonecrosis in oncological patients, the level of oral health is an important factor for the indication of intravenous bisphosphonates treatment.

Quality of life implications of bisphosphonate-associated osteonecrosis of the jaw

PURPOSE

Potentially debilitating, osteonecrosis of the jaw (ONJ) is an emerging complication of bisphosphonates. However, its effect on quality of life (QoL) is unknown. We determined the ONJ-related QoL decline in a cancer patient cohort.

PATIENTS AND METHODS

Thirty-four cancer patients with bisphosphonate-associated ONJ completed a telephone survey (October 2007 through May 2008). The Oral Health Impact Profile 14 (OHIP) retrospectively assessed participant oral health-related QoL before and after ONJ. Standardized ONJ descriptions were developed in a multidisciplinary, iterative process and were evaluated with three frequently used preference-based QoL measurement methods on a 0 (death) to 1 (perfect health) scale: Visual Analogue Scale (VAS), Time Trade-Off (TTO), and EQ-5D.

RESULTS

ONJ significantly (p < .001) increased OHIP scores (worse QoL) for additive (3.56-16.53) and weighted (7.0-17.5) methods. Seven individual OHIP items significantly increased (Bonferroni correction p < .0035): pain, eating discomfort, self-consciousness, unsatisfactory diet, interrupted meals, irritability, and decreased life satisfaction. Mean preference-based QoL values significantly decreased (p < .001) with worsening ONJ stage (VAS, TTO, and EQ-5D): no ONJ (0.76, 0.86, 0.82), ONJ stage 1 (0.69, 0.82, 0.78), ONJ stage 2 (0.51, 0.67, 0.55), and ONJ stage 3 (0.37, 0.61, 0.32). As ONJ worsened, EQ-5D domain scores significantly increased (p < .001). Pain/discomfort and anxiety/depression contributed most to declining QoL.

CONCLUSIONS

ONJ significantly affects QoL, a detriment that increases with worsening ONJ. QoL impairments for ONJ stages 2 and 3 are similar to other treatment side effects that influence decision-making. Bisphosphonate-associated ONJ QoL is an important consideration for patients, clinicians, and policy makers.

Oral tremor induced by the muscarinic agonist pilocarpine is suppressed by the adenosine A2A antagonists MSX-3 and SCH58261, but not the adenosine A1 antagonist DPCPX

Tremulous jaw movements in rats, which can be induced by dopamine (DA) antagonists, DA depletion, and cholinomimetics, have served as a useful model for studies of tremor. Although adenosine A(2A) antagonists can reduce the tremulous jaw movements induced by DA antagonists and DA depletion, there are conflicting reports about the interaction between adenosine antagonists and cholinomimetic drugs. The present studies investigated the ability of adenosine antagonists to reverse the tremorogenic effect of the muscarinic agonist pilocarpine. While the adenosine A(2A) antagonist MSX-3 was incapable of reversing the tremulous jaw movements induced by the 4.0mg/kg dose of pilocarpine, both MSX-3 and the adenosine A(2A) antagonist SCH58261 reversed the tremulous jaw movements elicited by 0.5mg/kg pilocarpine. Systemic administration of the adenosine A(1) antagonist DPCPX failed to reverse the tremulous jaw movements induced by either an acute 0.5mg/kg dose of the cholinomimetic pilocarpine or the DA D2 antagonist pimozide, indicating that the tremorolytic effects of adenosine antagonists may be receptor subtype specific. Behaviorally active doses of MSX-3 and SCH 58261 showed substantial in vivo occupancy of A(2A) receptors, but DPCPX did not. The results of these studies support the use of adenosine A(2A) antagonists for the treatment of tremor.

Toxicity and developmental defects of different sizes and shape nickel nanoparticles in zebrafish

Metallic nanoparticles such as nickel are used in catalytic sensing, and electronic applications, but health and environmental affects have not been fully investigated. While some metal nanoparticles result in toxicity, it is also important to determine whether nanoparticles of the same metal but of different size and shape changes toxicity. Three different size nickel nanoparticle (Ni NPs) of 30, 60, and 100 nm and larger particle clusters of aggregated 60 nm entities with a dendritic structure were synthesized and exposed to zebrafish embryos assessing mortality and developmental defects. Ni NPs exposure was compared to soluble nickel salts. All three 30, 60, and 100 nm Ni NPs are equal to or less toxic than soluble nickel while dendritic clusters were more toxic. With each Ni NP exposure, thinning of the intestinal epithelium first occurs around the LD10 continuing into the LD50. LD50 exposure also results in skeletal muscle fiber separation. Exposure to soluble nickel does not cause intestinal defects while skeletal muscle separation occurs at concentrations well over LD50. These results suggest that configuration of nanoparticles may affect toxicity more than size and defects from Ni NPs exposure occur by different biological mechanisms than soluble nickel.

Effect of homologous PRP on proliferation of human periodontally affected osteoblasts. In vitro preliminary study. Report of a case

OBJECTIVE

The purpose of this in vitro study was to evaluate the effect of two concentrations of homologous platelet-rich plasma (PRP) on the proliferative response of osteoblasts derived from a patient with aggressive periodontitis.

METHODS

8.5 ml of venous blood were taken from 1 healthy and non-smoker volunteer. PRP was prepared following the protocol of Curasan. Osteoblasts were derived from alveolar bone chips obtained from a patient with aggressive periodontitis during conventional periodontal surgery and a clinically healthy person during crown lengthening surgical procedure. Cells were grown in 24-well dishes and on day 2 of quiescence were treated with 1% and 5% (v/v) of PRP. The effect on cell proliferation was estimated by measuring [3H] thymidine incorporation. After 48h of incubation, cells were processed to subject to scintillation counting. Counts per minute were determined for each sample.

RESULTS

The addition of 1% and 5% of PRP provoked a statistical significant (p<0.05) increase in cell growth.

CONCLUSIONS

Data revealed significant enhancement of proliferative response of osteoblasts in the presence of PRP, which might serve as a source of growth factors promoting periodontal repair by modulating cell response and activities.

[Bisphosphonate-associated osteonecrosis of the jaw in patients with multiple myeloma]

Bisphosphonate-associated osteonecrosis of the jaw (BON) is mainly observed in patients with multiple myeloma, and to a lesser extent in breast and prostate cancer patients receiving intravenous treatment with potent bisphosphonates. The incidence of BON increases with the duration of bisphosphonate therapy and with the potency of the used bisphosphonate. BON usually develops after tooth extraction or other oral surgery, and has proven difficult to treat. Optimal dental hygiene should be ensured prior to treatment initiation where possible, and once bisphosphonate treatment is instituted, oral surgery should be avoided if possible.

Osteonecrosis of the jaw in patients with multiple myeloma treated with zoledronic acid

Intravenous bisphosphonates-the potent inhibitors of osteoclast-mediated bone resorption are among the most commonly prescribed drugs in the management of multiple myeloma (MM). Zoledronic acid (ZA) is a new generation potent intravenous bisphosphonate that has been approved for the treatment and prevention of bone lesions, and/or hypercalcemia associated with MM. Osteonecrosis of the jaw (ONJ) is an emerging serious side effect of the new generation bisphosphonates with a growing number of reports related to this pathological entity. ONJ usually appears following oral surgical and dental procedures but sometimes occur spontaneously. These cases are mostly seen and treated by dentists and oral surgeons. The aim of this study was to discuss the frequency, characteristics, risk factors, management and histopathological features of ZA induced ONJ based on the literature and illustrated with five own cases. Thirty-two patients with MM who received ZA for a median period of 26.5 +/- 18.7 months (min: 5 months, max: 76 months) were evaluated. ONJ was detected in five patients and mean drug duration time was 34 months. The frequency was 15% and the patients were usually symptomatic. There was no significant difference in terms of the duration of ZA in patients with and without ONJ. Management of these established cases were performed with medical treatment, minor debridement, sequestrectomy, and combining bone resection with autologous platelet rich plasma. Our data indicate that ZA therapy has a major role in the development of ONJ a fact that should be considered by physicians treating MM patients.

Ibandronate uptake in the jaw is similar to long bones and vertebrae in the rat

Intravenous bisphosphonates may be involved in the development of osteonecrosis of the jaw (ONJ). However, a mechanistic causality has not been demonstrated. To evaluate whether there is higher drug uptake by the jaw versus other bones that might be involved in ONJ pathogenesis, we performed a pilot experiment comparing ibandronate uptake in rat mandible, femur, and lumbar vertebrae after repeated administration. Rats (n = 1/group) received daily subcutaneous injections of ibandronate in doses ranging from 0.003 to 0.3 mg/kg/day for 9 days. Five days after the last injection, the animals were killed and the right femur, lumbar vertebrae L3-L5, and the right mandible were removed. After cleaning and drying, bone dry weight was recorded, and ibandronate concentration was determined in whole-bone hydrolyzates by gas chromatography mass spectrometry. Concentrations of ibandronate increased dose-dependently in all bones with similar concentrations per bone at each dose level ranging from values below quantification limit (low dose) up to approximately 10 ng ibandronate/mg bone dry weight (high dose). In this rat study, there was a relatively similar bisphosphonate uptake between the femur and lumbar vertebrae bones whereas the uptake in the jaw was statistically smaller with regard to the absolute values (P < 0.05). Thus, there is no suggestion of preferential bisphosphonate uptake in the jaw.

Bisphosphonate-related osteonecrosis of the jaws: a call for multidisciplinary approaches

Bisphosphonates have been prescribed for the treatments of oncologic and metabolic bone diseases to inhibit bone resorption of osteoclasts. However, in recent years, the increased numbers of cases diagnosed with exposed and necrotic bone localized in the jawbones associated with bisphosphonate use have been reported, mostly in patients with multiple myeloma or bone metastases who received long-term intravenous bisphosphonate treatments. The strong association between patients receiving dentoalveolar surgery and the incidence of this complication highlights the need for multidisciplinary approaches and necessitates the close attention from a team of health care personnel. The present review summarizes the current knowledge on etiology, risk factors, clinical presentations, and recommended preventive measures and managements for afflicted patients. In light of recent available data and because stanterdized management strategies have not been well established, prevention seems to be of paramount benefit to this group of patients.

Bisphosphonate-related osteonecrosis of the jaws (ONJ): a report of two cases

Osteonecrosis of thejaw (ONJ) is strongly associated with the use of aminobisphosphonates. Herein, the authors report two cases of ONJ after intravenous bisphosphonate therapy including clinical presentations, X-ray, and pathological findings. Since there is no definite treatment for ONJ, the focus should be on prevention with a dental evaluation for all patients before starting bisphosphonates.

The muscarinic receptor antagonist tropicamide suppresses tremulous jaw movements in a rodent model of parkinsonian tremor: possible role of M4 receptors

RATIONALE

Nonselective muscarinic acetylcholine antagonists have been used for several years as antiparkinsonian drugs. However, there are at least five subtypes of muscarinic receptor (M1-5). Neostriatal M4 receptors have been implicated in aspects of motor function, and it has been suggested that M4 antagonists could be used as treatments for parkinsonism.

OBJECTIVE

Currently, there is a lack of highly selective M4 antagonists that readily penetrate the blood brain barrier. Thus, the present studies focused upon the effects of tropicamide, a muscarinic acetylcholine receptor antagonist with moderate binding selectivity for the M4 receptor subtype.

MATERIALS AND METHODS

Tremulous jaw movements were used as a model of parkinsonian tremor in these studies, and the effects of tropicamide were compared with those of the nonselective muscarinic antagonist atropine.

RESULTS

Tropicamide suppressed the tremulous jaw movements induced by the muscarinic agonist pilocarpine and the dopamine antagonist pimozide. Analysis of the dose-response curves indicated that tropicamide showed approximately the same potency as atropine for suppression of pilocarpine-induced jaw movements but was more potent than atropine on the suppression of pimozide-induced jaw movements. In contrast, atropine was more potent than tropicamide in terms of impairing performance on visual stimulus detection and delayed nonmatch-to-position tasks.

CONCLUSIONS

These studies demonstrate that tropicamide, which currently is used clinically for ophthalmic purposes, can exert actions that are consistent with antiparkinsonian effects. Moreover, the different pattern of effects shown by tropicamide compared to those of atropine on motor vs cognitive tasks could be due to the modest M4 selectivity shown by tropicamide.

Is bisphosphonate-associated osteonecrosis of the jaw caused by soft tissue toxicity?

Osteonecrosis of the jaw (ONJ) is a complication of high-dose bisphosphonate use, characterized by the finding of exposed bone in the oral cavity. It has been assumed that the primary lesion lies in bone and is related to over-suppression of bone turnover, but it is unclear why such a lesion should present with loss of the soft tissue covering of the mandible or maxilla as the primary clinical feature. A possible explanation of this paradox is that bisphosphonate is accumulated in bone in concentrations sufficient to be directly toxic to the oral epithelium. This would result in the failure of healing of soft tissue lesions (such as those caused by invasive dental procedures or by subclinical trauma from dentures) leading to secondary infection of the underlying bone. This model would explain why bone resection is unhelpful in managing this problem, suggests that low bone turnover caused by non-bisphosphonate drugs should not cause the same problem, and raises the possibility that agents which reverse bisphosphonate effects in vitro might have a role in the management of ONJ.

Imaging findings of bisphosphonate-associated osteonecrosis of the jaws

BACKGROUND AND PURPOSE

Bisphosphonates are drugs that decrease bone turnover by inhibiting osteoclast activity. An association between the use of bisphosphonates and osteonecrosis of the maxilla and mandible has recently been described. This study describes the imaging findings of bisphosphonate-associated osteonecrosis of the jaws.

MATERIALS AND METHODS

This is a retrospective series of 15 clinically diagnosed patients, identified at 3 centers. Eleven patients were women, of whom 6 had breast cancer, 3 had osteoporosis, and 2 had multiple myeloma. Of the 4 male patients, 2 had prostate cancer, 1 had multiple myeloma, and 1 had osteoporosis. The age range of the patients was 52-85 years (average, 68 years). The mandible was the clinical site of involvement in 11 patients, and the maxilla was involved in 4 patients. Imaging consisted of orthopantomograms in 14 patients, CT scans in 5 patients, and radionuclide bone scan in 1 patient. Nine patients had sequential imaging. Two radiologists reviewed the images.

RESULTS

All of the patients had a degree of osseous sclerosis, most commonly involving the alveolar margin, but lamina dura thickening and full-thickness sclerosis were also observed. The sclerotic change encroached on the mandibular canal in 3 patients. Less commonly encountered findings included poorly healing or nonhealing extraction sockets, periapical lucencies, widening of the periodontal ligament space, osteolysis, sequestra, oroantral fistula, soft tissue thickening, and periosteal new bone formation.

CONCLUSIONS

The most common finding in bisphosphonate-associated osteonecrosis was osseous sclerosis. This varied from subtle thickening of the lamina dura and alveolar crest to attenuated osteopetrosis-like sclerosis.

[Osteonecrosis of the jaws by using bisphosphonates]

The new generation of bisphosphonates are often used in the treatment of osteoporosis or for certain tumors with bone defects. Between the period of September 2005 and May 2006 we have treated 8 patients at our clinic with a bisphosphonate-induced osteonecrosis in the maxillofacial region. All of these patients went through intravenous bisphosphonate treatment earlier. We have chosen two cases, where the appearance of side effects can be named as typical. Based upon the increasing number of international articles reporting and our own experiences in this matter, we would like to draw attention to the importance of prevention in treating these patients. In case of symptoms, if temporary suspension of the bisphosphonate therapy does not have severe consequences, combination of surgical and long-term antibiotic therapy could be the solution.

Involvement of apoptotic cell death and cell cycle perturbation in retinoic acid-induced cleft palate in mice

Retinoic acid (RA), a metabolite of vitamin A, plays a key role in a variety of biological processes and is essential for normal embryonic development. On the other hand, exogenous RA could cause cleft palate in offspring when it is given to pregnant animals at either the early or late phases of palatogenesis, but the pathogenetic mechanism of cleft palate caused by excess RA remains not fully elucidated. The aim of the present study was to investigate the effects of excess of RA on early palatogenesis in mouse fetuses and analyze the teratogenic mechanism, especially at the stage prior to palatal shelf elevation. We gave all-trans RA (100 mg/kg) orally to E11.5 ICR pregnant mice and observed the changes occurring in the palatal shelves of their fetuses. It was found that apoptotic cell death increased not only in the epithelium of the palatal shelves but also in the tongue primordium, which might affect tongue withdrawal movement during palatogenesis and impair the horizontal elevation of palatal shelves. In addition, RA was found to prevent the G(1)/S progression of palatal mesenchymal cells through upregulation of p21(Cip1), leading to Rb hypophospholylation. Thus, RA appears to cause G(1) arrest in palatal mesenchymal cells in a similar manner as in various cancer and embryonic cells. It is likely that apoptotic cell death and cell cycle disruption are involved in cleft palate formation induced by RA.

Osteochemonecrosis of jaws and bisphosphonates

Osteochemonecrosis of the jaws is a well described side effect of bisphosphonate therapy. Bisphosphonates are non metabolised analogues of pyrophosphate that are capable of localizing to bone, slowing both rate of growth and rate of dissolution therefore reducing the rate of bone turnover. Although the exact mechanism is not clear but it has been established that bisphosphonates target osteoclast, inhibiting their function in several ways: There are two types of bisphosphonates. The first are oral preparations of bisphosphonates, which include Alendronate and Risedronate. They are indicated for the treatment of osteoporosis. They are considered as lower risk of osteochemonecrosis. The second are administered intravenously. Pamindronate is a first generation bisphosphonate; 90 mg administered intravenouly over 2-24 hours every 3-4 weeks. The next generation of intravenous bisphosphonate is Zoldronic acid, which is more effective than Pamidronate in controlling hypercalcaemia of bone and reducing the skeletal related events in patients with metastatic breast cancer, multiple myeloma, hypercalcaemia of malignancy, paget's disease and bone metastasis from prostate and lung cancer.

Biochemical characterization of collagen in alveolar mucosa and attached gingiva of pig

Alveolar mucosa and attached gingiva are two continuous but functionally distinct connective tissues covering alveolar bone of the jaw. In this study, the major matrix component of these tissues, collagen, was biochemically characterized and compared. The tissues were obtained from mature pigs and analyzed for collagen content, amino acid composition, collagen types, collagen cross-linking, and gene expression. We found that alveolar mucosa is primarily composed of fibrillar collagens and the collagen content is higher than attached gingiva. The content of type III relative to type I collagen was higher in alveolar mucosa when compared with attached gingiva. The collagen cross-linking pattern also was distinct between the two tissues demonstrating that alveolar mucosa contained fewer reducible cross-links but more non-reducible cross-links in comparison to attached gingiva. The mRNA expression level of type I collagen in alveolar mucosa was significantly lower than that of attached gingiva. These results indicate that alveolar mucosa is a fibrillar collagen-rich tissue and, in comparison to gingival tissue, re-models slowly.

Dopamine and adenosine receptor interaction as basis for the treatment of Parkinson's disease

Preclinical evidence strongly indicate that adenosine A(2A) receptor antagonists represent a promising class of drugs for the treatment of motor deficits associated to Parkinson's disease. The effects of adenosine A(2A) receptor antagonists were here assessed in a rat model of parkinsonian tremor induced by cholinomimetic drugs by evaluating the counteraction of tremulous jaw movements. Systemic administration of the A(2A) antagonist SCH 58261 dose-dependently reduced the magnitude of perioral tremor induced by the acetylcholinesterase inhibitor tacrine (2.5 mg/kg). Furthermore, intrastriatal infusion of SCH BT2 (5 microg/microl), a water-soluble analogue of SCH 58261, antagonized tacrine-induced jaw movements with a maximal effect in the ventrolateral striatum. On the other hand, SCH 58261 (5 mg/kg) was ineffective in blocking tremulous jaw movements stimulated by the direct muscarinic agonist pilocarpine (1 mg/kg). Taken together, these results indicate that A(2A) antagonists reduce parkinsonian tremor stimulated in rats by tacrine and that the striatum is deeply involved in the observed effect. Moreover, the ineffectiveness of SCH 58261 in blocking pilocarpine-stimulated perioral tremor suggests that the antitremorigenic effects of A(2A) antagonists described here are not related to a direct action on muscarinic receptor. The prospective of providing additional antitremor benefits considerably enhances the therapeutic potential of A(2A) antagonists.

Role of melanin in mechanical properties of Glycera jaws

The remarkable mechanical prowess of the jaws of the bloodworm Glycera dibranchiata appears to be a consequence of a robust cross-linked network of organic molecules, notably melanin and proteins, as well as small amounts of unmineralized Cu and a Cu-based mineral. The present study focuses on the role of melanin. Mechanical properties of untreated jaws and the constituent melanin are probed through nanoindentation, both in air and underwater. Complementary information is obtained from density and porosity measurements and attempts at Cu removal from the jaws using EDTA, an effective metal chelator in most biological systems. In near-tip regions of the jaws, mechanical properties attain the highest values and diminish only slightly when wet (by 15-25%), in contrast to the behavior of other organic biomaterials. The melanin constituent contributes significantly to the mechanical integrity of the jaw; its hardness and elastic modulus are about half those of untreated jaws. Although melanin may be the dominant shape-determining component of the structure, it remains to be shown whether jaw assembly is mediated by protein deposition on a melanin scaffold or, conversely, by melanin deposition on a protein scaffold. The inability of EDTA to chelate Cu from the jaws and the relatively high density of the jaws and the melanin support the notion of a highly cross-linked molecular structure. Finally, based on the metric H(3)/E(2) (H being hardness and E the Young's modulus), the results suggest that the abrasion resistance of the jaws is superior to all engineering polymers and competitive with the hardest metallic alloys.

Impairment of lower jaw growth in developing zebrafish exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin and reduced hedgehog expression

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) has been shown to cause a multitude of detrimental effects to developing zebrafish (Danio rerio). Previously, we demonstrated that jaw growth was impaired by TCDD exposure, but the exact mechanism underlying these malformations remained unknown. In the present study, we investigated the involvement of hedgehog genes and their downstream signaling in TCDD-mediated jaw malformation. We demonstrate that the developing lower jaw expresses sonic hedgehog a (shha), sonic hedgehog b (shhb) and their receptors, patched1 (ptc1) and patched2 (ptc2), as well as the downstream transcription factors, gli1 and gli2a. Loss of Hh signaling in mutants (sonic you) and larvae treated with a Hh inhibitor (cyclopamine), resulted in similar effects as those caused by TCDD. Moreover, TCDD exposure caused downregulation of shha and shhb in a manner dependent on aryl hydrocarbon receptor 2 (ahr2). Although this suggested an involvement of Hh signaling in TCDD-mediated impairment of jaw growth, we did not observe downregulation of ptc1 and ptc2, receptors dependent on Hh signaling. Furthermore, while the overall occurrence of apoptosis in the developing jaw was minimal, it was significantly increased in larvae treated with cyclopamine. In contrast, both TCDD and cyclopamine markedly reduced immunoreactivity against phosphorylated histone 3, a cell proliferation marker in the developing jaw. Taken together, our data suggest that Ahr2-mediated downregulation of Hh signaling, leading to a failure of cell proliferation, contributes to TCDD induced inhibition of lower jaw growth. TCDD may impair jaw growth through other pathway(s) in addition to Hh signaling.