Glauce Crivelaro do Nascimento

Time-dependent analysis of nociception and anxiety-like behavior in rats submitted to persistent inflammation of the temporomandibular joint

Temporomandibular disorder (TMD) is prevalent in dental clinics and can involve problems with the masticatory muscles or the temporomandibular joints (TMJ). The pain of TMD is frequently associated with inflammation in the TMJs, but its etiology is considered to be multifactorial and includes biologic, behavioral, environmental, social, emotional and cognitive factors. The purpose of this investigation was to evaluate the anxiety-like behavior in rats exposed to temporomandibular inflammation via injection of Freunds Adjuvant (CFA) with the elevated plus maze (EPM) and light/dark box (LDB) tests and to evaluate nociceptive behavior with the von Frey test at different periods. Moreover, this study measured TMJ inflammation using plasma extravasation (Evans blue test) and the intraarticular infiltration of polymorphonuclear neutrophils (myeloperoxidase quantification). The results showed that rats that were submitted to TMJ inflammation exhibited a decreased number of entries into the open arms of the EPM and a decrease in the time spent in the light compartment and in the number of transitions in the LDB. Additionally, the number of entries in closed arms in the EPM, used as indicator of locomotor activity, did not alter between treatments. Furthermore, increases in mechanical sensitivity and increases in plasma extravasation in the joint tissue occurred throughout the inflammation process, along with an increase in myeloperoxidase in the synovial fluid of TMJ. Our results suggest that the temporomandibular inflammation induced by CFA produced anxiety-like behaviors in rats and induced nociceptive behavior across different periods of inflammation.

Common positioning errors in panoramic radiography: A review

Professionals performing radiographic examinations are responsible for maintaining optimal image quality for accurate diagnoses. These professionals must competently execute techniques such as film manipulation and processing to minimize patient exposure to radiation. Improper performance by the professional and/or patient may result in a radiographic image of unsatisfactory quality that can also lead to a misdiagnosis and the development of an inadequate treatment plan. Currently, the most commonly performed extraoral examination is panoramic radiography. The invention of panoramic radiography has resulted in improvements in image quality with decreased exposure to radiation and at a low cost. However, this technique requires careful, accurate positioning of the patients teeth and surrounding maxillofacial bone structure within the focal trough. Therefore, we reviewed the literature for the most common types of positioning errors in panoramic radiography to suggest the correct techniques. We would also discuss how to determine if the most common positioning errors occurred in panoramic radiography, such as in the positioning of the patients head, tongue, chin, or body.

Herbal mouthwash containing extracts of Baccharis dracunculifolia as agent for the control of biofilm: clinical evaluation in humans.

Baccharis dracunculifolia DC (Asteraceae), popularly known as “alecrim-do-campo,” is largely distributed in South America, is shown to exhibit protective actions against gastric ulcers, has anti-inflammatory properties, and is hepatoprotective. Several essential oils obtained from Baccharis species possess biological activities, such as antimicrobial and antivirus activities. This randomized controlled trial evaluated the efficacy of B. dracunculifolia in the reduction of dental biofilm, comparing this natural product with other mouthwashes already known in the dental market. In measuring the time after use of mouthwash (t = 1), there was no difference between products (P = 0.602); that is, subjects in the study had a similar PI after the first use. After one week (t = 2), there was no difference between the four products evaluated (P = 0.674), so, all research individuals completed the study with a similar reduction in dental biofilm between themselves but it was different from initial state (Friedman test). It is possible to conclude that B. dracunculifolia had the same efficiency of the materials used to oral hygiene in reduction of dental plaque and, consequently, prevention of dental caries. Thus, we can consider B. dracunculifolia as a good candidate for new material to be implemented in dental care.

Muscle characterization of reactive oxygen species in oral diseases

Abstract Importance and objective. Reactive Oxygen Species (ROS) are oxygen-derived molecules that are unstable and highly reactive. They are important signaling mediators of biological processes. In contrast, excessive ROS generation, defective oxidant scavenging or both have been implicated in the pathogenesis of several conditions. This biological paradox of ROS function contributes to the integrity of cells and tissues. So, the aim of this review was examined for published literature related to ‘reactive oxygen species and dentistry and muscle’. Materials and methods. A PubMed search was performed by using the following key words: ‘reactive oxygen species and dentistry and muscle’. Results. Involvement of ROS in pathologic conditions can be highlighted in oral diseases like periodontitis, orofacial pain, temporomandibular disorders and oral cancer. Also, several studies have correlated the increase in ROS production with the initiation of the muscle fatigue process and the process of muscle injury. However, studies evaluating the relation of ROS and orofacial muscles, which can prove very important to understand the fatigue muscle in this region during oral movements, have not yet been conducted. Conclusions. It is concluded that the data on skeletal muscles, especially those of mastication, are not commonly published in this data source; therefore, further studies in this field are strongly recommended.

Chronic stress effects in contralateral medial pterygoid muscle of rats with occlusion alteration.

Temporomandibular disorder (TMD) has a high prevalence in our society, characterized by a severe pain condition of the masticatory muscles and temporomandibular joint. Despite the indication of multiple factor initiators of TMD, there is still controversy about its etiology and its pathophysiology is poorly understood. Using rats as experimental animals we investigated the effect of unpredictable chronic stress with or without unilateral molar extraction on the contralateral medial pterygoid muscle. Our hypothesis is that these two factors induce changes in morphology, oxidative metabolism and oxidative stress of muscle fibers. Young adult male Wistar rats (±200g) were divided into four groups: a group with extraction and unpredictable chronic stress (E+US); with extraction and without stress (E+C); without extraction and with unpredictable chronic stress (NO+US); and a control group without either extraction or stress (NO+C). The animals were subjected to unilateral extraction of the upper left molars, under intraperitoneal anesthesia with 4% Xylazine (10mg/kg) and 10% Ketamine (80mg/kg) on day zero. The rats of groups E+US and NO+US were submitted to different protocols of stress, from the 14th day after the extraction. The protocols were different every day for five consecutive days, which were repeated from the 6th day for five days more. Contralateral medial pterygoid muscles were obtained on the 24th day after the start of the experiment for morphological, metabolic, capillary density, and oxidative stress analysis. The data from capillary density showed a decrease of capillaries in animals subjected to dental extraction, compared with those without extraction and an increase of laminin expression in the group submitted to the unpredictable chronic stress when compared to the unexposed to stress. SDH test revealed a decrease of light fibers in the group submitted to unilateral extraction of molars, compared with this area in the control group. In E+US and NO+US groups, the deeply stained fibers increased compared to NO+C.·The exodontia factor was able to increase the ROS activity in muscle, whereas the stress factor does not significantly alter ROS in this tissue. It was concluded that both unpredictable chronic stress and the extraction induce metabolic and density of capillary changes in the contralateral medial pterygoid muscle to extraction, suggesting that these factors for a longer period of this experiment could induce muscle damage related to TMD.

Metabolic Changes in Masseter Muscle of Rats Submitted to Acute Stress Associated with Exodontia.

Clinical evidence has shown that stress may be associated with alterations in masticatory muscle functions. Morphological changes in masticatory muscles induced by occlusal alterations and associated with emotional stress are still lacking in the literature. The objective of this study was to evaluate the influence of acute stress on metabolic activity and oxidative stress of masseter muscles of rats subjected to occlusal modification through morphological and histochemical analyses. In this study, adult Wistar rats were divided into 4 groups: a group with extraction and acute stress (E+A); group with extraction and without stress (E+C); group without extraction and with acute stress (NO+A); and control group without both extraction and stress (NO+C). Masseter muscles were analyzed by Succinate Dehydrogenase (SDH), Nicotinamide Adenine Dinucleotide Diaphorase (NADH) and Reactive Oxygen Species (ROS) techniques. Statistical analyses and two-way ANOVA were applied, followed by Tukey-Kramer tests. In the SDH test, the E+C, E+A and NO+A groups showed a decrease in high desidrogenase activities fibers (P < 0.05), compared to the NO+C group. In the NADH test, there was no difference among the different groups. In the ROS test, in contrast, E+A, E+C and NO+A groups showed a decrease in ROS expression, compared to NO+C groups (P < 0.05). Modified dental occlusion and acute stress - which are important and prevalent problems that affect the general population - are important etiologic factors in metabolic plasticity and ROS levels of masseter muscles.

Metabolic and vascular pattern in medial pterygoid muscle is altered by chronic stress in an animal model of hypodontia

Psychological stress is an important perpetuating, worsening and risk factor for temporomandibular disorders of muscular or articular origin. Occlusion instability, by the way, is considered a risk factor of this pathology and can be reproduced in some experimental animal models. The exact physiologic mechanism underlying these relations however, remains unclear. Our purpose was to test the hypothesis that chronic stress and unilateral exodontia induce metabolic and vascular changes in the medial pterygoid muscle of rats. Adult Wistar rats were submitted to chronic unpredictable stress and/or unilateral exodontia and their plasma and medial pterygoid muscle were removed for analysis. The parameters evaluated included plasma levels of corticosterone, metabolic activity by succinate dehydrogenase, oxidative capacity by nicotinamide adenine dinucleotide diaphorase, capillary density by laminin and alfa-CD staining and reactive oxidative species production. Chronic unpredictable stress as an isolated factor, increased oxidative metabolism, capillary density and reactive oxygen species production at medial pterygoid muscle. Conversely, exodontia has a main effect in metabolism, promoting glycolytic transformation of muscle fibers. Association of both factors induced a major glycolytic pattern in muscle and vascular changes. Our findings provide insights into the mechanisms, possibly inducing metabolic and vascular alterations on medial pterygoid muscle of rats, by which chronic stress and occlusal instabilities might be involved as risk factors in the pathophysiology of temporomandibular disorders with muscular components.

The therapeutic potential of cystathionine gamma-lyase in temporomandibular inflammation-induced orofacial hypernociception

Hydrogen sulfide (H2S) is an endogenous neuromodulator produced mainly by the enzyme cystathionine gamma-lyase (CSE) in peripheral tissues. A pronociceptive role of endogenously produced H2S has been previously reported by our group in a model of orofacial inflammatory pain. Using the established persistent orofacial pain rat model induced by complete Freunds adjuvant (CFA) injection into temporomandibular joint (TMJ), we have now investigated the putative role of endogenous H2S modulating hypernociceptive responses. Additionally, plasmatic extravasation on TMJ was measured following different treatments by Evans blue dye quantification. Thus, rats were submitted to Von Frey and Formalin tests in orofacial region before and after pharmacological inhibition of the CSE-H2S system combined or not with CFA-induced TMJ inflammation. Pretreatment with CSE inhibitor, propargylglycine (PAG; 88.4 μmol/kg) reduced temporomandibular inflammatory pain when injected locally as well as systemically. In particular, local PAG injection seems to be more effective for hypernociceptive responses in orofacial persistent inflammation since its action is evidenced in the majority analyzed periods of the inflammatory process compared to its systemic use. Moreover, local injection seems to act on temporomandibular vascular permeability, evidenced by decreased plasmatic extravasation induced by local PAG administration. Our data are consistent with the notion that the endogenous synthetized gas H2S modulates persistent orofacial pain responses revealing the pharmacological importance of the CSE inhibitor as a possible therapeutic target for their control.

Nociceptive Response to l -DOPA-Induced Dyskinesia in Hemiparkinsonian Rats

Non-motor symptoms are increasingly identified to present clinical and diagnostic importance for Parkinson’s disease (PD). The multifactorial origin of pain in PD makes this symptom of great complexity. The dopamine precursor, l-DOPA (l-3,4-dihydroxyphenylalanine), the classic therapy for PD, seems to be effective in pain threshold; however, there are no studies correlating l-DOPA-induced dyskinesia (LID) and nociception development in experimental Parkinsonism. Here, we first investigated nociceptive responses in a 6-hydroxydopamine (6-OHDA)-lesioned rat model of Parkinson’s disease to a hind paw-induced persistent inflammation. Further, the effect of l-DOPA on nociception behavior at different times of treatment was investigated. Pain threshold was determined using von Frey and Hot Plate/Tail Flick tests. Dyskinesia was measured by abnormal involuntary movements (AIMs) induced by l-DOPA administration. This data is consistent to show that 6-OHDA-lesioned rats had reduced nociceptive thresholds compared to non-lesioned rats. Additionally, when these rats were exposed to a persistent inflammatory challenge, we observed increased hypernociceptive responses, namely hyperalgesia. l-DOPA treatment alleviated pain responses on days 1 and 7 of treatment, but not on day 15. During that period, we observed an inverse relationship between LID and nociception threshold in these rats, with a high LID rate corresponding to a reduced nociception threshold. Interestingly, pain responses resulting from CFA-induced inflammation were significantly enhanced during established dyskinesia. These data suggest a pro-algesic effect of l-DOPA-induced dyskinesia, which is confirmed by the correlation founded here between AIMs and nociceptive indexes. In conclusion, our results are consistent with the notion that central dopaminergic mechanism is directly involved in nociceptive responses in Parkinsonism condition.

The Therapeutic Use of Propolis Extract in Alveolar Bone Contaminated with Bacterial Endotoxin

Propolis is a resinous substance obtained by bees, whose antibacterial, anti-inflammatory, antiviral, antifungal, immune stimulant, and local anesthetic wound healing properties have been considered for clinical practice. In particular, its anti-inflammatory and antibacterial characteristic seems to be a novel target for infectious process from dental origin. This work aimed to evaluate the propolis antibacterial potential against a bacterial endotoxin on dental alveoli. First, some properties of green propolis extract were analyzed (in vitro): 1) physicochemical profile 2) Minimum Inhibitory Concentration (MIC) against endotoxin from Gram negative Escherichia coli, and 3) its immunoregulatory activity on leukocytes from the spleen of rats. Then, an inflammatory process was induced in rats by a contamination with lipopolysaccharide (LPS) that is recognized as an endotoxin. For this purpose, rats were subjected to extractions of maxillary first molars, right and left, which immediately had the right dental socket contaminated with 0.1L of LPS (100 μg/kg). After 14 days from exodontia, these individuals were divided in groups treated with Pure Propolis Extract (EPP) and groups without therapy. The contaminated alveolar bone or the same area from animals without inflammation-induced were removed for histological and immunohistochemical processing. Our data reveal an important therapeutic action from green propolis. In vitro tests indicated low cytotoxicity for this compound. By a hematoxilin and eosin analysis, the group infected and treated with propolis presented the alveoli with more new bone tissue, characterized by bony trabeculae circling small cavities filled by a loose connective tissue containing blood vessels. Additionally, a histochemical marker of osteoclasts, tartrateresistant acid phosphatase (TRAP), was used to determine the new bone formation rate. The propolis induced more TRAP formation on alveolar bone infected by LPS. Our findings highlight the potential of propolis to be applied in dental material.