The role of P2X3 receptors in bilateral masseter muscle allodynia in rats.

AIM: To determine the relationship between bilateral allodynia induced by masseter inflammation and P2X3 receptor expression changes in trigeminal ganglia (TRG) and the influence of intramasseteric P2X3 antagonist administration on bilateral masseter allodynia. METHODS: To induce bilateral allodynia, rats received a unilateral injection of complete Freund's adjuvant (CFA) into the masseter muscle. Bilateral head withdrawal threshold (HWT) was measured 4 days later. Behavioral measurements were followed by bilateral masseter muscle and TRG dissection. Masseter tissue was evaluated histopathologically and TRG tissue was analyzed for P2X3 receptor mRNA expression by using quantitative real-time polymerase chain reaction (PCR) analysis. To assess the P2X3 receptor involvement in nocifensive behavior, two doses (6 and 60 µg/50 µL) of selective P2X3 antagonist A-317491 were administrated into the inflamed masseter muscle 4 days after the CFA injection. Bilateral HWT was measured at 15-, 30-, 60-, and 120-minute time points. RESULTS: HWT was bilaterally reduced after the CFA injection (P<0.001). Intramasseteric inflammation was confirmed ipsilaterally to the CFA injection. Quantitative real-time PCR analysis demonstrated enhanced P2X3 expression in TRG ipsilaterally to CFA administration (P<0.01). In comparison with controls, the dose of 6 µg of A-317491 significantly increased bilateral HWT at 15-, 30-, and 60-minute time points after the A-317491 administration (P<0.001), whereas the dose of 60 µg of A-317491 was efficient at all time points ipsilaterally (P=0.004) and at 15-, 30-, and 60-minute time points contralaterally (P<0.001). CONCLUSION: Unilateral masseter inflammation can induce bilateral allodynia in rats. The study provided evidence that P2X3 receptors can functionally influence masseter muscle allodynia and suggested that P2X3 receptors expressed in TRG neurons are involved in masseter inflammatory pain conditions.

TRPV1 channel-mediated bilateral allodynia induced by unilateral masseter muscle inflammation in rats.

Pain in masticatory muscles is among the most prominent symptoms of temperomandibular disorders (TMDs) that have diverse and complex etiology. A common complaint of TMD is that unilateral pain of craniofacial muscle can cause a widespread of bilateral pain sensation, although the underlying mechanism remains unknown. To investigate whether unilateral inflammation of masseter muscle can cause a bilateral allodynia, we generated masseter muscle inflammation induced by unilateral injection of complete Freund's adjuvant (CFA) in rats, and measured the bilateral head withdrawal threshold at different time points using a von Frey anesthesiometer. After behavioral assessment, both right and left trigeminal ganglia (TRG) were dissected and examined for histopathology and transient receptor potential vanilloid 1 (TRPV1) mRNA expression using quantitative real-time PCR analysis. A significant increase in TRPV1 mRNA expression occurred in TRG ipsilateral to CFA injected masseter muscle, whereas no significant alteration in TRPV1 occurred in the contralateral TRG. Interestingly, central injection of TRPV1 antagonist 5-iodoresiniferatoxin into the hippocampus significantly attenuated the head withdrawal response of both CFA injected and non-CFA injected contralateral masseter muscle. Our findings show that unilateral inflammation of masseter muscle is capable of inducing bilateral allodynia in rats. Upregulation of TRPV1 at the TRG level is due to nociception caused by inflammation, whereas contralateral nocifensive behavior in masticatory muscle nociception is likely mediated by central TRPV1, pointing to the involvement of altered information processing in higher centers.

Alterations in the masseter muscle and plasma IL-6 level following experimentally induced occlusal interference and chronic stress--a study in rats.

This study was undertaken to examine the alteration of masseter and plasma interleukin-6 after inducing occlusal interference and chronic stress. Male Wistar rats were submitted to chronic stress procedure, exposed to occlusal interference, or exposed to both mentioned procedures. Whole blood and masseter tissue were collected to determine interleukin-6 level, measured by means of ELISA. Masseter pain was evaluated using the orofacial formalin test. Masseter interleukin-6 level was significantly higher in animals submitted to combination of occlusal interference and chronic stress than in the control group (p<0.05). There was positive and significant correlation between pain response and masseter interleukin-6 level (r=0.5741; p<0.0003). No significant differences in plasma interleukin-6 level were found between groups (p>0.05), as well as no correlation with pain (p>0.05). Combination of occlusal interference and chronic stress leads to strong local reaction characterized by high levels of masseter interleukine-6. High concentrations of muscle interleukin-6 and its correlation with pain point to inflammatory background of masticatory muscle pain.

Implant prosthetic rehabilitation of the patients with mandibular resection following oral malignoma surgery.

Patient underwent mandibular resection due to surgical therapy of oropharingeal malignoma. Facial asymmetry and cosmetic distortion are frequent consequences of such interventions, which may also include deviation and intrusion of the mandible, motor and sensory disorders, abnormal intermaxillary relations and malocclusion. Implant-supported prosthesis could be an optimal solution to prosthodontic treatment of such patients. However, there is a problem in determination of stable (interocclusal) intermaxillary relations. This article describes the choice of therapy and procedures undertaken in prosthetic rehabilitation of a patient who underwent mandibular resection and radiotherapy with supported prosthesis retained with four implants.

Multivariate analysis of different factors affecting the patient general satisfaction with complete dentures.

The aim of the study was to investigate different factors that affect the level of patient's general satisfaction with maxillary and mandibular complete dentures (CDs) using a multivariate analysis. A total of 100 CD wearers participated in this study. There were 46 men (37-77 years old; mean age 62.6 +/- 9.2) and 54 women (34-77 years old; mean age 60.9 +/- 9.3). In the questionnaire the patients answered the questions regarding gender, age, number of previous CDs worn, the present dentures' age and denture-wearing habits. Participants rated the level of their satisfaction with the esthetics, retention, speech, mastication, sense of taste, comfort and general satisfaction with their CDs. More than 70% of the examined patients claimed all the examined variables to be the best-score category. Of the 9 factors examined, satisfaction with the mastication and esthetics, denture-wearing habits and satisfaction with retention in the maxilla explained the variability of the patients's general satisfaction with their CDs by 72%. Satisfaction with the mastication, denture-wearing habits and satisfaction with speech and comfort in mandible explained the variability of the patients's general satisfaction with their CDs by 79%. These findings suggest that the general patient satisfaction with maxillary CDs is related more to the mastication and retention abilities, as well as with esthetics and denture-wearing habits, while in the mandible CDs is related to mastication and speaking abilities, denture-wearing habits and comfort of wearing.

Masticatory muscle and temporomandibular joint pain in Croatian war veterans with posttraumatic stress disorder.

The aim of this study was to investigate the prevalence and intensity of masticatory muscle and temporomandibular joint (TMJ) pain in Croatian war veterans with posttraumatic stress disorder (PTSD). The examined group consisted of 100 Croatian war veterans, in whom PTSD had previously been diagnosed. Patients were compared with 92 subjects who had not taken part in the war and in whom PTSD was excluded by psychiatric examination. The clinical examination consisted of palpation of the masticatory muscles, the prominent neck musculature, and TMJ. The examination technique used and the definition of items were previously tested for reliability and validity. 93% of the subjects with PTSD had masticatory muscle tenderness compared to 45.65% of the subjects in the control group (chi2 = 51.46, p < 0.0001). The most frequent painful location in the subjects with PTSD was the left lateral pterygoid site in 88%, and in subjects of the control group the right lateral pterygoid site in 28.26% of cases. The most painful location in the PTSD group was the left lateral pterygoid site in 72%, and in the control group the left posterior digastric in 4.35% of cases. 58% of the subjects with PTSD had TMJ tenderness compared to 3.26% of subjects in the control group (chi2 = 66.23, p < 0.0001). The most frequent painful location of TMJ in both groups was the left posterior capsule; in the PTSD group 38% and in subjects in the control group 2.17% of cases. The most painful location was the left posterior capsule in 28% of subjects with PTSD, while not one subject in the control group reported severe painful sensitivity. The very high frequency and intensity of pain in subjects with PTSD confirms the effect of stress on muscle and joint sensitivity, i.e. perception of pain.

A new classification of resin-based aesthetic adhesive materials.

The purpose of this article is to illustrate a new classification of resin based aesthetic materials laying on the characterization of their matrix and their filler morphology. Four samples per material have been prepared for SEM evaluation. Each sample has been treated with chloroform to dissolve its matrix in order to evidence the filler morphology. A general schema of four different matrix systems which characterize the material's level of hydrophobicity can be put in evidence. The subsequent filler analysis individuates a more complex schema based on filler size and construction. A new classification based on matrix nature and filler morphology has been proposed. Based on this concept mechanical and aesthetic characteristics of the materials can be presumed.

Influence of mechanical and chemical degradation on surface gloss of resin composite materials.

PURPOSE: To determine the changes in surface gloss of different composite materials after simulation of mechanical and chemical aging mechanisms. METHODS: 36 specimens were fabricated for each material and polished with 120-, 220-, 500-, 1200-, 2400- and 4000- grit SiC abrasive paper, respectively. Gloss measurements were made with a glossmeter (Novo-Curve) prior to testing procedures. Specimens of each material were randomly divided into three groups. Group 1 was conditioned for 7 days at 37 degrees C in 75% ethanol aqueous solution. Group 2 was immersed in fluoride gel (Elmex Gelée) at 37 degrees C for 1 hour. Group 3 was subjected to simulated toothbrushing with an electric toothbrush while being immersed in toothpaste. Surface gloss measurements were made subsequently. RESULTS: Significant difference between surface gloss of the composite materials tested were detected after simulated brushing (Kruskal Wallis, P < 0.05). With the exception of Filtek Silorane, all composite materials tested were significantly affected by immersion in Elmex Gelèe (Wilcoxon signed-rank test, P < 0.05). Immersion in 75% alcohol aqueous solution significantly affected surface gloss except natural enamel and Durafill (Wilcoxon signed-rank test, P< 0.05).

Influence of chronic stress and oclusal interference on masseter muscle pain in rat.

This study aimed to investigate the individual effects of chronic stress and occlusal interference, as well as their combined influence on masseter muscle pain. Experiments were performed on 28 male Wistar rats. Animals were submitted to chronic stress procedure, exposed to occlusal interference, or exposed to both mantioned procedures. At the end of the procedure animals were submitted to orofacial formalin test, and nociceptive behavioral response was evaluated. Statisticaly significant difference of nociceptive behavioral response in chronicaly stressed rats and in the animals with occlusal interference in comparation to the control group were not obtained (p > 0.05). In contrast, nociceptive behavioral response was significantly increased in rats submitted to both of experimental procedures (p < 0.01). These findings suggest that only combination of occlusal interference and chronic stress influence masseter muscle pain.

A Cross-Sectional Study of the Influence of Tooth Color Elements on Satisfaction with Smile Esthetics.

PURPOSE: This study investigated the influence of tooth color on patients' satisfaction with the esthetics of their smiles. MATERIALS AND METHODS: A shade guide was used to determine the color of the maxillary anterior teeth in 671 participants. Self-reported satisfaction was assessed through five criteria: tooth appearance, color, shape, and position and appearance of the gingiva. The Psychosocial Impact of Dental Aesthetics Questionnaire and an Oral Impact on Daily Performances questionnaire were also used. RESULTS: The predictors of higher patient satisfaction were lower chroma, higher lightness, and uniform color of all maxillary anterior teeth. These are significant but weak predictors of satisfaction with smile esthetics. CONCLUSION: Color has a low level of influence on satisfaction with a smile's esthetics.

The prevalence of temporomandibular disorders in war veterans with post-traumatic stress disorder.

The purposes of this study were to assess the prevalence of temporomandibular disorders in Croatian war veterans suffering from post-traumatic stress disorder (PTSD) and to analyze the impact of the disease on mandibular function. One hundred eighty-two male subjects participated in the study. The examined group consisted of 94 subjects who had taken part in the war in Croatia and for whom PTSD had previously been diagnosed. Patients were compared with an age- and gender-matched group of subjects who had not taken part in the war and for whom PTSD was excluded by means of a psychiatric examination. The study used a clinical examination and standard questionnaire. Statistically significant differences were found in almost all measured parameters. With regard to restricted movements, overbite, and overjet, the differences obtained did not have clinical significance. The most significant differences were found in the parameters of pain. Headache was experienced by 63.83% of the subjects with PTSD, facial pain by 12.77%, and pain in the region of the jaw by 10.64%. Headache was the most intense pain, with an average intensity of 4.92 on a scale of 0 to 10. Pain on loading, temporomandibular joint clicking, and intrameatal tenderness were more prevalent in the PTSD group than in the healthy control group. The study supports the concept that PTSD patients are at increased risk for the development of temporomandibular disorder symptoms.

Early and late effects of X-irradiation on submandibular gland: a morphological study in mice.

BACKGROUND: Radiotherapy for head and neck cancers causes permanent salivary gland dysfunction and xerostomia. The aim of this study was to determine changes in mice submandibular glands after X-irradiation. METHODS: The submandibular glands of male C57BL/6 mice were locally X-irradiated in the head and neck region with a single dose of 7.5 or 15 Gy and analyzed morphologically and morphometrically at 1, 3, 6, 10, 40, and 90 days after irradiation. RESULTS: Two phases of gland reaction to irradiation have been noted. The first, early phase is observed up to 10 days after irradiation. The second, late phase was observed 90 days after irradiation. Also, a dose-related effect was noticed. The most prominent morphological changes were pyknotic nuclei, vacuolization of acinar cells and lysis of acini and granular convoluted tubules. Changes were detected at 3 and 6 days after irradiation followed by tissue regeneration. Ninety days after irradiation, prominent pathological changes (vacuolization and pyknotic nuclei of acinar cells, lysis of acini and granular convoluted tubules and edema) were detected, but the most remarkable change was disseminated mononuclear infiltration. Also, a statistically significant reduction in number of acinar cells was detected in both irradiated glands. CONCLUSIONS: Occurrence of disseminated mononuclear infiltration in gland during late post-irradiation phase makes the mouse model potentially better than the rat model for investigation of irradiation-induced salivary gland damage.

Oral health status and temporomandibular disorders in multiple sclerosis patients.

Multiple sclerosis (MS) is an inflammatory disease of unknown etiology involving the central nervous system. Certain clinical manifestations affect the oro-facial region. Three in particular should be of interest to the dentist: trigeminal neuralgia, sensory neuropathy of the trigeminal nerve and facial palsy. The aim of this study was to determine the oral health status, the frequency of subjective symptoms and temporomandibular disorders (TMD) subtype according to Research diagnostic criteria for temporomandibular disorders (RDC/TMD) among MS patients. Examinees in this study were 50 patients suffering from MS, who were at least once treated during their disease in the Clinic Hospital Center, Rijeka, Clinic for Neurology. All examinees had to meet the diagnostic criteria for clinically and laboratory confirmed MS, according to Poser. The results show the difference in mean DMFT (decayed, missing, filled teeth) between MS and the control group. The number of decayed and missing teeth was higher, but the number of filled teeth was significantly lower in MS group. Eighty-two per cent of the subjects with MS had a least one symptom of dysfunction compared with 24% of the subjects in the healthy control group. In the present study, pain, the pain during mouth opening, the difficulty with mouth opening and temporomandibular joint (TMJ) sounds were more commonly reported in the MS group than in the control group. This study shows a statistically significant excess of dental caries and temporomandibular disorders among MS patients compared with the control group. These results suggest that MS is a possible etiological factor in temporomandibular disorders.

CO-OCCURRENCE OF CHRONIC HEAD, FACE AND NECK PAIN, AND DEPRESSION IN WAR VETERANS WITH POST-TRAUMATIC STRESS DISORDER.

This study investigated the relationship between chronic head, face and neck pain, and the level of depression in Croatian war veterans with post-traumatic stress disorder (PTSD). The presence of self-reported pain, pain on digital palpation, and pain severity in masticatory and neck muscles, temporomandibular joints and sinuses, as well as the level of depression were assessed in a group of war veterans with PTSD (n=52). Control groups consisted of war veterans without PTSD (n=50) and healthy men that were not engaged in war actions and were free from PTSD (n=50). The number of self-reported pain and number of painful sites were correlated with the level of depression. More self-reported pain and painful sites were recorded in the group of war veterans with PTSD as compared with either war veterans without PTSD or healthy men. Furthermore, PTSD patients mostly suffered from severe depression. There was a statistically significant positive correlation between all investigated pain parameters and level of depression. As the most important finding, the present study demonstrated chronic head, face and neck pain to be related to depression in PTSD patients.

The effect of frequent removable partial denture wearing on alveolar bone resorption.

AIM: To determine the influence of frequent removable partial denture (RPD) wearing on the alveolar bone density changes around the abutment teeth. METHODS: Fifty examinees of both genders, wearing partial dentures, were included in the study. Thirty one of the examinees (62%) were wearing the dentures 24 hours a day, while nineteen (34%) of them were wearing them only during the day. The changes in the bone density around the abutment teeth were determined by the intraoral microdensitometry method. Standard retroalveolar radiographs were performed twice. The first one before the removable partial denture delivery and the second one after a period of three-month denture wearing. A copper step wedge consisting of five steps (0.1-0.5 mm) was attached to the radiograph in order to calibrate it. Seven points, regions of interest (ROI) close to the root of the abutment tooth, all ten pixels in size, were selected on each radiograph. Grey areas in the regions of interest were measured and converted into the copper step wedge thickness equivalents in order to estimate the change in the alveolar bone density and measure the difference in alveolar bone density between two radiographs. RESULTS: The results indicated that there is not any statistically relevant change (t-value less than 2,011; t(49,0.05) / F less than 4,0426; F0.05(1,48)) in the alveolar bone density depending on the frequency of removable partial denture wearing. CONCLUSION: The frequency of removable partial denture wearing does not cause any changes in the alveolar bone density around the abutment teeth in the period of three-month denture wearing.

Dive-related fatalities among tourist and local divers in the northern Croatian littoral (1980-2010).

BACKGROUND: The aim of the study was to retrospectively analyze diving fatalities occurring in Primorje-Gorski Kotar County (northern Croatian littoral), Croatia between 1980 and 2010 in order to identify differences between fatally injured tourist and resident divers, as well as temporal changes in the frequency of diver deaths. METHODS: Medico-legal and police reports of 47 consecutive fatal diving cases were reviewed to determine the frequency of death among divers in relation to year and month of death, age, sex, nationality, organization of diving, diving type, and health condition. RESULTS: The majority of victims were foreign citizens (59.6%) most of whom fell victim to scuba diving (70.4%). It was found that 79% of resident divers succumbed during free-diving. The number of diving fatalities increased significantly in the last three decades, especially among free-divers. Of the victims, 93% were males, usually belonging to younger age groups with tourist divers being significantly older than local divers. And 31.9% of divers, mostly tourists, showed signs of acute, chronic, or congenital pathological conditions. CONCLUSION: Fatally injured foreign divers differ from resident diver fatalities in diving method and age. Tourists are the group most at risk while scuba diving according to the Croatian sample. Occupational scuba divers and free-divers are the group most at risk among resident divers. This study is an important tool in uncovering the most common victims of diving and the related risk factors. It also highlights the problems present in the legal and medical monitoring of recreational divers and discusses possible pre-event, event, and post-event preventive actions that could lead to reduced mortality rates in divers.

Factors influencing a patient's decision to choose the type of treatment to improve dental esthetics.

BACKGROUND/AIM: Interest in dental esthetics has increased rapidly during the last few decades among both patients and dentists, and the creation of a natural dental appearance has become an important task in all fields of dentistry, especially in prosthodontics and restorative dentistry. The aim of this research was to investigate factors influencing a patient's decision to choose the type of treatment to improve dental esthetics. METHODS: A total of 700 Caucasian subjects participated in the cross-sectional study (261 men, 439 women, aged 18-86 years, mean age 46.2 +/- 18.6). The study included clinical examination and a self-administrated questionnaire based on self-perceived esthetics, satisfaction with the appearance of their maxillary anterior teeth and previous dental experience. Multiple logistic regression was used in statistical analysis. RESULTS: Hiding teeth during smile was the most important predictor for choosing fixed prosthetic restorations (OR 9.1), followed by self-perceived bad fixed prosthesis, malpositioned teeth and female gender (OR 2.9, 2.4, and 1.5, respectively). The increase in satisfaction with dental appearance and previous orthodontic therapy reduced chances for seeking prosthetic therapy (each OR 0.4). The significant predictors for bleaching choosing were hiding teeth during smiling, already done bleaching, female gender, lower levels of satisfaction with dental appearance and the absence of the previous orthodontic therapy (OR 5.8, 2.4, 1.8, 0.5 and 0.4, respecitively). Hiding teeth during smile, self-perceived malposition and crowding, and lower levels of satisfaction, were significant predictors for choosing orthodontic treatment (OR 3.1, 2.4, 2.2 and 0.6, respectively). None of current dental statuses was statistically significant predictor for choosing prosthodontic, bleeching nor orthodontic therapy. CONCLUSION: The psychological elements and female gender are the main predictors of seeking dental therapy. Understanding the prevalence of dissatisfaction with the present esthetics and desired treatments to improve esthetics can be a guide for strategies for intervention to improve esthetics.