Materials for interocclusal records and their ability to reproduce a 3-dimensional jaw relationship

PURPOSE: The purpose of this study was to determine if accuracy and dimensional stability of vinyl polysiloxanes and irreversible hydrocolloids stabilized by a tray used for fixed prosthodontics, removable partial, and complete denture cases are comparable to those of waxes and record rims and if storage time (24 hours or 6 days) affects dimensional stability of the tested materials. MATERIALS AND METHODS: Two waxes, two record rims, three vinyl polysiloxanes, and one irreversible hydrocolloid (alginate) were examined. Three pairs of master casts with measuring steel rods were mounted on an articulator (initial position). Five records were made of each material, and the upper cast was remounted after 24 hours or 6 days so that deviations from the initial position could be measured. RESULTS: Vinyl polysiloxanes reinforced by a stabilization tray were the most accurate materials able to reproduce a settled interocclusal position. Mounting casts (fixed prosthodontics cases) without records gave accuracy similar to wax records. Record rims used for removable partial and complete denture cases produced lesser accuracy than vinyl polysiloxanes and irreversible hydrocolloid stabilized by a tray. Accuracy was not significantly affected by storage time. CONCLUSION: The results show that accuracy of vinyl polysiloxanes and irreversible hydrocolloids reinforced by a tray is superior to that of record rims with regard to the complete denture case and is among the most accurate with regard to the removable partial denture case. For fixed prosthodontics, however, reinforcement is unnecessary.     

The clinical assessment of oral dryness is a significant predictor of salivary gland hypofunction

OBJECTIVES: To compare subjective complaints of xerostomia and salivary gland dysfunction and a clinical assessment of oral dryness with an objective measurement of salivary gland dysfunction, in a group of UK patients attending a Dry Mouth Clinic. The aim of the study was to identify signs and symptoms that may be of predictive value for salivary gland hypofunction (SGH) in clinical practice. METHODS: This prospective study investigated 214 patients who attended a Dry Mouth Clinic, held at Liverpool University Dental Hospital. Patients gave a history of xerostomia for a minimum of 6 months and were asked standardised questions to subjectively assess oral dysfunction. The oral mucosa was then clinically assessed for dryness and sialometry was performed. Unstimulated whole saliva flow rates (UFR) of < 0.2 ml min-1 were considered to be indicative of SGH. RESULTS: One or more symptoms of oral dysfunction were reported in 178 (83%) patients, in addition to xerostomia. The clinician diagnosed oral dryness in 105 patients. Objective evidence of SGH was found in 125 (58%) of patients. The clinicians' subjective assessment of oral dryness was indicative of a reduced UFR (P < 0.0001) and a significant predictor of an UFR < 0.2 ml min-1 using logistic regression analysis (odds ratio 9.6; 95% CI 4.8 and 19.3). The mean UFR of patients who reported symptoms of oral dysfunction was significantly lower than the mean UFR of patients who reported no oral dysfunction. Using logistic and multiple regression analyses, symptoms of oral dysfunction were not found to be significant predictors of either an UFR < 0.2 ml min-1 or a reduced UFR. CONCLUSIONS: The clinical assessment of oral dryness was a significant predictor of SGH, in this selected group of patients. Patients who complain of xerostomia may have additional symptoms of oral dysfunction indicative of a reduced UFR.     

Palatal angioleiomyoma. A clinical case

A case of angioleiomyoma localized at the level of the soft palate is reported. The 31-year-old patient presented a non-pathognomonic clinical picture and the anamnestic finding of the relatively slow growth of the neoformation raised problems of differential diagnosis in relation to benign growth and lesion of a non-neoplastic nature. The differential diagnosis was only obtained with histological examination of biopsy material.     

Possible regulation of epidermal growth factor-receptor tyrosine autophosphorylation by calcium and G proteins in chemically permeabilized rat UMR106 cells

A model using chemically permeabilized cells was developed to examine mechanisms that regulate protein tyrosine phosphorylation in osteoblastic cells. Using either permeabilized UMR106 osteoblastic or A431 (reference) cells, epidermal growth factor (EGF)-induced cellular tyrosine phosphorylation, and whether there are previously unrecognized interactions between this transduction pathway and Ca2+- or G protein-dependent signalling pathways, were investigated. Both permeabilized cell types, when maintained in non-supplemented cytoplasmic substitution solution (basic CSS), responded to EGF (1-100 ng/ml) with dose-dependent increases in tyrosine phosphorylation. A complex and time-dependent pattern of phosphotyrosine-containing proteins resulted, but the profile of tyrosine phosphorylated proteins was appreciably less complex than in intact cells. Supplementation of basic CSS with MgATP restored the normal complexity of the profiles for EGF-induced tyrosine phosphorylation proteins in both permeabilized cell lines and produced a more sustained accumulation of phosphoprotein products in A431 cells. Adding Ca2+ (< or = 10(-6) M), with or without exogenous MgATP, dose-dependently attenuated EGF-induced tyrosine phosphorylation of EGF receptors (EGFR) and other substrates in UMR106 cells, but was less effective in A431 cells. In both cell types, genistein, an inhibitor of tyrosine kinases, was more effective in attenuating EGF-induced receptor tyrosine phosphorylation in permeabilized cells. Similarly, orthovanadate, an inhibitor of protein tyrosine phosphatases, stimulated the accumulation of phosphoprotein products more effectively in permeabilized cells. Thus, the permeabilization preserves many features of intact cells while facilitating manipulation of intracellular conditions. NaF reproducibly produced a significant vanadate-like action in permeabilized cells that was somewhat stronger than its effect on intact cells. In contrast, the well-known inhibition of tyrosine phosphorylation by phorbol 12-myristate 13-acetate (PMA) was less effective in permeabilized cells than in intact cells; these actions of PMA were Ca2+-dependent. In addition, guanylyl-imidodiphosphate (Gpp(NH)p) attenuated tyrosine phosphorylation in UMR106 cells, and this effect was specifically blocked by guanosine 5'-O-(2-thiodiphosphate) (GDPbetas). These results strongly suggest that there is crosstalk between EGFR-activated tyrosine phosphorylation/dephosphorylation pathways and both Ca2+- and G protein-mediated pathways in UMR106 cells, revealing a previously unrecognized modulation of EGF signalling in osteoblast-like cells that contrasts with the simpler regulatory mechanisms found in A431 cells.     

Esthetic outcome of implant-supported single-tooth replacements assessed by the patient and by prosthodontists

PURPOSE: The objective of this study was to assess and compare patients' and clinicians' judgments of the esthetic outcome of implant-supported single-tooth replacements. MATERIALS AND METHODS: In all, 29 patients with 41 single implant-supported crowns in the maxillary anterior region participated in the study. The esthetic outcome of the implant-supported crowns was assessed by the patients and by 5 prosthodontists by means of a questionnaire in which various esthetics-related variables were addressed and responded to using visual analogue scales. Multiple regression analyses were used to evaluate the influence of the variables on the "overall satisfaction" with the implant-supported crown. RESULTS: Most variables in the patients' assessments revealed mean values above 90% and median values close to 100%. No single factor used in the multiple regression analysis was found to influence a patient's satisfaction with appearance of the crown at a statistically significant level. The clinicians' degree of satisfaction was for all variables lower than that of the patients. In 89% of the cases the clinicians could correctly locate the single implant-supported crown. Among the variables assessed, surrounding soft tissue appearance and form of the crown had the strongest influence on the clinician's overall satisfaction with the appearance of the crown. CONCLUSION: Appreciation of the esthetic outcome of the single implant-supported crowns was rated higher by the patients than by the prosthodontists. Furthermore, factors considered by professionals to be of significance for the esthetic result of the restorative treatment may not be of decisive importance for the patient's satisfaction.     

Evaluation of antibacterial activity of three dentin primers using an in vitro tooth model

This study compared the antibacterial activities of three dentin primers and investigated a newly designed experimental system using a bovine tooth model method for evaluating antibacterial activity by comparing this method with a conventional disk diffusion method. The antibacterial activities of SA primer in Clearfil Liner Bond, LB primer in Clearfil Liner Bond II, and ED primer in Panavia 21 were evaluated using the conventional disk diffusion method. The 50 microliters aliquot of each primer was applied to three sterilized paper disks, then placed onto Tryptic Soy agar plates already inoculated with Streptococcus mutans. After anaerobic incubation for 48 hours, the diffusion of antibacterial components was determined using the inhibition zone produced around the paper disk. The diameter of the inhibition zones was measured and the average calculated. Standardized cavities (diameter 5.0 mm, depth 3.0 mm) were prepared on the labial surfaces of bovine teeth and inoculated with S mutans (10(6) CFU/microliter) following sterilization by 60Co gamma rays (50 KGy). The teeth were divided into four groups: SA primer, LB primer, ED primer, and a control group. Except for the control teeth, the cavity preparations were treated with the respective dentin primers, and then firmly sealed with a temporary sealing material. The teeth were placed in bottles containing melted Tryptic Soy agar. Five ml of Tryptic Soy broth was then added to the surface of the hardened Tryptic Soy agar. After 1 week's incubation of the teeth in the bottles at 37 degrees C, the number of bacteria remaining in each cavity was counted, except for eight specimens, which were used for SEM observation. The ED primer showed the widest inhibition zone in the disk diffusion test, which was significantly different from the other primers. Using the bovine tooth model, all dentin primers showed antibacterial activity, with significant differences found among the four groups. The results indicated that ED primer had the strongest antibacterial effect among the three primers.     

CAD/CAM-copings for partial coverage

Aim of the study was to evaluate the Computer Integrated Ceramic Reconstruction (CICERO)-system and the Ceramic Reconstruction (CEREC)-system for the production of all ceramic copings for partial coverage. Posterior teeth were prepared and the stone dies were made. Accuracy analyses were performed on ceramic restorations made by means of the CICERO and by means of the CEREC technique. The marginal gaps were compared to that of a control cast metal restoration. The results demonstrate that the marginal gaps of the CICERO and CEREC copings varied respectively for the premolar 58-80 microns (mean 69 microns) and 71-91 microns (mean 81 microns). For the upper molar 63-92 microns (mean 78 microns) and 68-110 microns (mean 89 microns) and for the lower molar 54-98 microns (mean 76 microns) and 73-99 microns (mean 86 microns). Control cast metal partial coverage restorations showed marginal gaps of 33, 49 and 41 microns. It is concluded that computers can produce copings for partial coverage preparations on stone dies with a mean marginal gap for CICERO copings of 74 microns and for CEREC copings of 85 microns. These values were obtained before optimizing the marginal fit by means of porcelain veneering.     

Sjögren's syndrome. Consequences for oral health

Sj?gren's syndrome is an auto-immune disease involving exocrine glands causing amongst others xerostomia and dry eyes. Many other tissues may be affected as well. Early recognition of this disease may help to alleviate signs and symptoms and is, thus, important. The aim of this paper is to provide the dentist with knowledge to enable him to timely diagnose the oral component of Sj?gren's syndrome as well as to give guidelines for the treatment.     

Heterotransplantation of human neoplasms.

The heterotransplantation of 39 solid human neoplasms into athymic and asplenic-athymic mice resulted in the successful growth of 28 of the transplants. However, only 17 of the tumors could be maintained in serial passage. Metastasis or local infiltration by the transplanted tumors was not observed. Melanomas and colorectal carcinomas grew well whereas other types grew poorly or not at all. Possible factors responsible for the poor growth or lack of growth are discussed. The rapid growth of a melanoma in newborn mice in contrast with the slow growth of the same tumor in adult mice suggests a new experimental approach for transplantation of malignancies which previously have been difficult to establish.