A study of the bond strength and color of ultralow-fusing porcelain

PURPOSE: The purpose of this study was to investigate the effects of different bonding agents, surface roughness, and acid pickling on the bond strength and color of ultralow-fusing porcelain fused to gold alloy. MATERIALS AND METHODS: Porcelain-metal specimens were made to 25 mm x 3 mm x 0.5 mm with a 1-mm porcelain thickness. A 3-point bending test was used to evaluate the bond strength. The color of the porcelain was measured using a dental chromameter, and the data were processed in the CIE Lab system. The color difference (delta E*) was calculated for the tested groups. RESULTS: Good bond strength and color could be achieved regardless of the use and type of bonding agent. Surface roughness and acid pickling had more effect on the bond strength than on color. CONCLUSION: The type of the bonding agent, surface roughness, and acid pickling influenced the bond strength but had minimal effects on the color of ultralow-fusing porcelain. This ultralow-fusing porcelain could produce a color closer to the Vita shade than the conventional low-fusing porcelain.     

Conscious survey of dental patients. 1. Questionnaire related to general dentistry (in the case of the new patients of the Nippon Dental University Hospital)

Increased information on dentistry in the mass media in recent years may have caused changes in patients' attitudes toward dental care. To better understand patient' attitudes, we conducted a questionnaire survey of patients on the first visit to our hospital. Of 384 responses, 196 were eligible for statistical analysis. The following findings were obtained. 1. Among the motives for visiting a dental clinic, "Manifestation of pain or symptoms" was given by majority (85.7%) of respondents, followed by "detection of abnormality" (20.4%). The percentage of patients wanting treatment of "any part suggested by the dentist" was highest (35.7%), followed by those expecting "treatment including cleaning" (30.1%). The above results indicate that patients still tend to visit a clinical after subjective symptoms appear and leave the content of treatment to the dentist. However, an increasing number of patients appear to be concerned with their oral condition and visit a clinic before manifestation of symptoms. 2. Among factors in selecting their dentist, "expertise" obtained the highest percentage, 87.2%, followed by "providing prompt treatment" (38.8%) and "trying to avoid pain" (32.1%), in that order. Dissatisfaction with dentists was described as "no explanation of treatment" in 57.1%, "lack of sympathetic attitude" in 38.3% and "easily resorts to tooth extraction" in 35.4%. These results suggest that patients expect good human relations with their dentists, sufficient explanations of treatments and sympathetic consideration, as well as expertise. 3. The majority of patients (85.7%) hoped to receive instructions on oral hygiene and to be increased interest in information above prophylaxis. Meeting their needs will remain a future issue for dentists.     

Teeth contacting habit as a contributing factor to chronic pain in patients with temporomandibular disorders

Many different factors are known to cause and perpetuate the symptoms of temporomandibular disorders (TMD). However, the roles of parafunctional factors have not been clearly elucidated. We found one of these habits in the clinical setting. This parafunctional habit involves daily light touching of the upper and lower teeth, when the mouth is closed. We named this habit Teeth Contacting Habit (TCH). [OBJECTIVES] To investigate the following hypotheses: 1) TCH is associated with perpetuation of chronic pain of TMD patients; 2) TCH is associated with other behavioral factors. [METHODS] Two hundred and twenty-nine TMD outpatients with chronic pain were analyzed with multivariate logistic regression models. [RESULTS] TCH was found in 52.4% of patients. Patients with TCH and pain lasting for more than four months were less likely to experience improvements in pain at the first visit (OR = 1.944, p = 0.043). Other factors associated with TCH were as follows: unilateral chewing (OR = 2.802) and involvement in a precision job (OR = 2.195). [CONCLUSION] TCH can prolong TMD pain and is associated with other behavioral factors.     

Levels of soluble cytokine factors in temporomandibular joint effusions seen on magnetic resonance images

OBJECTIVE: To elucidate the correlations between joint effusion (JE) on T2-weighted magnetic resonance images (MRI) of the temporomandibular joint (TMJ) and the levels of various cytokine receptors, cytokine antagonists, and protein in the synovial fluid of patients with temporomandibular joint disorders (TMD). STUDY DESIGN: Fifty-five TMJs of 55 patients with TMD were scanned by MRI, and synovial fluid samples were obtained on the same day. The grade of JE was evaluated on a scale of 0 to 3: Grades 0 and 1 indicated absence, and grades 2 and 3 indicated the presence of JE. Correlations were evaluated between JE and the concentrations of soluble tumor necrosis factor receptors I and II (sTNFR-I and sTNFR-II, respectively), IL-6 soluble receptor (IL-6sR), IL-1 soluble receptor type II, and IL-1 receptor antagonist and protein in the synovial fluid of patients with TMD. RESULTS: The concentrations of sTNFR-I and protein in the group with JE (18 joints) were significantly higher than in the group without JE (37 joints). In addition, there were significant positive correlations between the grade of JE and the levels of sTNFR-I, sTNFR-II, and protein. CONCLUSIONS: sTNFRs and protein may play important roles in the pathogenesis of TMD. These mediators seem to influence the expression of JE, which may reflect synovial inflammation of the TMJ.     

Dipeptide utilization by the periodontal pathogens Porphyromonas gingivalis, Prevotella intermedia, Prevotella nigrescens and Fusobacterium nucleatum

Porphyromonas gingivalis, Prevotella intermedia, Prevotella nigrescens and Fusobacterium nucleatum, which can frequently be isolated from periodontal pockets, preferentially utilize proteins and peptides as growth substrates. In this study, we determined the size of peptide that is preferentially utilized as a source of energy and material for cell growth by P. gingivalis, P. intermedia, P. nigrescens and F. nucleatum using various sizes of poly amino acids consisting of two to approximately 100 molecules of aspartate or glutamate. Resting cells of P. gingivalis, P. intermedia and P. nigrescens utilized aspartylaspartate, while cells of P. gingivalis and F. nucleatum utilized glutamylglutamate. The addition of aspartylaspartate to the culture medium increased the growth of P. gingivalis, P. intermedia and P. nigrescens, while the addition of glutamylglutamate promoted the growth of P. gingivalis and F. nucleatum. These results clearly indicate that dipeptides such as aspartylaspartate and glutamylglutamate can be utilized as growth substrates for P. gingivalis, P. intermedia, P. nigrescens and F. nucleatum.     

Effect of bruxism-like activity on the salivary Chromogranin A as a stress marker

Summary  The aim of this study was to determine whether measuring salivary chromogranin A (CgA) is useful in assessing individual stress levels and whether bruxism-like activity influences the salivary CgA level. From 44 adult healthy volunteers, we collected saliva samples with and without a stress condition (loud unpleasant sound). We assayed salivary samples with an ELISA to determine the content of CgA. We investigated also the effect of bruxism-like activity on salivary CgA production during stress. There were three patterns (group A, B, C) of response to the stressor on salivary CgA. They showed different responses and different effects of bruxism-like activity. This study shows the possibility of evaluating stress levels of individuals by measuring salivary CgA. Salivary CgA responds to psychosomatic stress. Bruxism-like activity prevented a stress-induced increase of salivary CgA in group A and B (75% of subjects), suggested that the reaction of the sympathetic-adrenomedullary system is regulated by the bruxism-like activity of the masticatory organ. The effect of bruxism-like activity in group C (high baseline of salivary CgA) was different from the effect in group A and B. Correspondence: S. Sato, Dept. of Craniofacial Growth Development Dentistry, Division Orthodontics, Kanagawa Dental College, 82 Inaoka-cho, Yokosuka, 238-8580 Japan