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.

Proinflammatory cytokine levels in saliva in patients with burning mouth syndrome before and after treatment with low-level laser therapy.

The aim of this study was to determine the levels of proinflammatory tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) cytokines in whole unstimulated saliva in subjects with burning mouth syndrome (BMS) before and after treatment with low-level laser therapy (LLLT). BMS is characterized by a continuous, painful burning sensation in a clinically normal-appearing oral mucosa. A sample consisting of 40 consecutive subjects was selected on a voluntary basis from the pool of patients who presented for diagnosis and treatment of BMS at the Oral Medicine Unit of the Faculty of Medicine of the University of Rijeka. For determination of salivary levels of TNF-α and IL-6, ELISA (Sigma Immunochemicals, St. Louis, MO, USA) was performed to determine the salivary levels of TNF-α and IL-6. After 4 weeks of LLLT, the salivary levels of TNF-α and IL-6 in the experimental group decreased significantly (p < 0.001). There was no significant difference in the experimental group regarding visual analogue scale.

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.

Influences of age and maxillary anterior teeth status on patient's satisfaction with dental appearance and tooth colour.

OBJECTIVES: To study the impact of age, gender, tooth colour and maxillary anterior teeth status on patient's satisfaction with their dental appearance. MATERIAL AND METHODS: A total of 259 Caucasian subjects participated in the study (119 men, mean age 56 years; 140 women, mean age 61 years) divided into three age groups (young <35 age; middle aged 35-54 age; old ≥55 age). Their maxillary anterior teeth status was classified into three groups: (1) natural teeth (NTG) group; (2) composite filling group (CFG) and (3) porcelain-fused-to-metal fixed prosthodontic restoration group (FPDG). The participants judged appearance and tooth colour using a scale with three categories: completely dissatisfied, moderately dissatisfied and completely satisfied. RESULTS: Almost half of the participants were completely satisfied with their dental appearance and tooth colour. Half of the 'young' and 'middle-aged' participants with natural maxillary anterior teeth were completely satisfied and half of the 'old' participants were moderately satisfied with their dental appearance and tooth colour. The majority of participants with composite restorations (45-51%) were moderately satisfied with their dental appearance, one-third of 'young' and 'middle-aged' participants were moderately satisfied or dissatisfied with their tooth colour and more than 70% of older participants were dissatisfied with their tooth colour (p > 0.05). CONCLUSIONS: Satisfaction with the appearance of the maxillary anterior teeth differed both between individuals of different age and different dental status.

Relations between anterior permanent teeth, dental arches and hard palate.

The width and length of the anterior teeth, the dimensions of the frontal dental arches and the dimensions of the hard palate were measured (24 men and 56 women, age range of 18-30 years). The results showed gender-related dimorphism only for the cervical width of the maxillary canine, which were wider in men, p < 0.05. The width-to-length ratios of the maxillary frontal teeth varied from 0.82 to 0.91. The tooth-to-tooth width ratios among different maxillary frontal teeth varied from 0.78 to 0.91. The sum of all anterior maxillary teeth widths was equal to the hamular width and to the distal maxillary arch width (p > 0.05), meaning that the sum of the frontal artificial teeth width may be selected upon the measurement of the hamular width on the hard palate. The ratios between the maxillary and the mandibular frontal dental arch dimensions are representative values for the skeletal class I.

3-D stress analysis in first maxillary premolar.

The aim of this study was to investigate the stress distribution in a 3-D model of two-rooted tooth (first maxillary premolar) under two different occlusal force vectors by using finite element analysis. In the first model overall force of 200 N was divided into three vectors (cusp to fossa occlusion), and in the second model overall force was divided into 4 vectors (cusp to fossa and cusp to marginal ridge occlusion). The greatest compressive stress was found at the dentino- enamel junction in the cervical area of the both models (about -200 MPa). The greatest tensile stress was found at the vestibular aspect of buccal cusp in second model (about +3 MPa) and in the central fossa of the both models (about +28 MPa). Results indicate that in the both types of occlusal loadings the stress distribution was mainly compression and compressive forces were predominant over tensile stresses. In the second model with 4 vectors, stresses generated in the tooth structure were higher compared to the stresses generated in the first model with 3 vectors.

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.