Electrophysiological properties of fast- and slow-adapting units and their generator potentials of the frog tongue

The purpose of this study was to determine the stimulus response properties of fast and slow adapting units in the fungiform papillae of the frog tongue. Secondly, fast- and slow- adapting generator potentials were recorded from fast and slow-adapting mechanoreceptors in the single fungiform papilla glossopharyngeal nerve preparations, respectively. Results I. Impulse response properties of fast- and slow-adapting units 1) Most of the fungiform papillae were innervated by both fast- and slow-adapting units. Fast-adapting units evoked 1-4 impulses to each stimulus and the adaptation time was less than 17.5 msec. Slow-adapting units evoked 27.8 +/- 8.0 impulses (range: 11-49 impulses n = 18) during a pressure stimulation of 3 sec, and the adaptation time was 1.64 +/- 0.73 sec (range: 0.53-2.86 sec, n = 18). 2) Threshold, latency and absolute refractory period for fast-adapting units were 7.0 +/- 1.9 microns (range: 3.0-11.8 microns, n = 189), 2.31 +/- 1.29 msec (range: 0.85-6.80 msec, n = 31) and 2.9 +/- 1.0 msec (range: 1.8-5.6 msec, n = 33), respectively. Those for slow-adapting units were 4.6 +/- 1.8 microns (range: 2.0-11.8 microns, n = 152), 13.54 +/- 11.29 msec (range: 2.00-54.00 msec, n = 35) and 6.5 +/- 3.6 msec (range: 1.9-19.6 msec, n = 35), respectively. 3) A fast-adapting unit innervated 5.1 +/- 2.5 fungiform papillae (range: 1-13 fungiform papillae, n = 58) and the receptive area was 0.342 +/- 0.312 mm2 (range: 0.005-1.548 mm2, n = 55). A slow-adapting unit innervated 3.3 +/- 2.0 fungiform papillae (range: 1-12 fungiform papillae, n = 50) and the receptive area was 0.158 +/- 0.144 mm2 (range: 0.006-0.616 mm2, n = 29). 4) Conduction velocity of the fast-adapting unit was 23.0 +/- 3.1 m/sec (range: 15.0-30.6 m/sec, n = 528) and that of the slow-adapting unit was 12.8 +/- 2.2 m/sec (range: 4.4-21.1 m/sec, n = 495). The conduction velocity was calculated from the time necessary to conduct at two different points of the nerve fiber. 5) The upper limits of fast- and slow-adapting units for vibratory stimulation were 62.7 +/- 10.5 Hz (range: 50-80 Hz, n = 15) and 34.5 +/- 9.6 Hz (range: 15-45 Hz, n = 10), respectively. II.(ABSTRACT TRUNCATED AT 400 WORDS)     

Nifedipine and cyclosporin affect fibroblast calcium and gingiva

It has been stated that cyclosporin and nifedipine produce gingival overgrowth. However, the specific pathogenic mechanism remains uncertain. We used an experimental rat model to test the hypothesis that changes in collagen metabolism and numbers of gingival blood vessels are not mediated by intracellular calcium concentration (ratiometric Fura-2 AM measurement) in gingival fibroblasts. In the cyclosporin group, both width (364.2 +/- 67.5 mum) and microvessel density (number of vessels/mm(2), stained with anti-CD34 antibody) (41.6 +/- 5.1) of gingiva were statistically different when compared with those in the control group (width = 184.3 +/- 35.2 mum, microvessel density = 19.6 +/- 2.4). The nifedipine group showed the highest content of collagen (proportion of total stroma occupied by collagen, stained with Picro-Mallory) (nifedipine group = 66.3 +/- 9.4, cyclosporin group = 55.2 +/- 7.9, control group = 30.1 +/- 10.2). Freshly cultured fibroblasts from the cyclosporin group exhibited higher ratiometric values of fluorescence than did both the control and nifedipine groups (p = 0.03). Our results support the hypothesis that changes in gingival collagen metabolism are not mediated by calcium intracellular oscillations.     

Kinematic and kinetic observations on ballistic depression and elevation of the human mandible

To study mandibular motions with respect to time (kinematics) and the forces causing and resulting from these motions (kinetics), four subjects generated rapid depression and elevation of the mandible (displacement of 0.224 m; peak velocity of 0.237 m s(-1) during depression and 0.269 m s(-1) during elevation). The motion of depression (duration of 0.195 s; kinetic energy of 2.072 x 10(-3) J) could be divided into a phase of acceleration (2.742 m s(-2); +/- 0.28 gn) and a phase of deceleration (2.264 m s(-2); - 0.23 gn), and the terminal excess kinetic energy of depression was absorbed and dissipated by, primarily, the temporomandibular joint. Similarly, the ensuing motion of elevation (duration of 0.182 s; kinetic energy of 2.948 x 10(-3) J) could be divided into a phase of acceleration (3.498 m s(-2); + 0.36 gn) and a phase of deceleration (2.931 m s(-2); -0.30 gn), and the terminal excess kinetic energy of elevation was absorbed and dissipated by, primarily, the dentitions and, secondarily, by the temporomandibular joint. Rapid depression of the mandible appeared to be under the central control of a preprogrammed motor command, and ensuing rapid elevation of the mandible appeared to be under the peripheral control of a segmental and/or transcortical reflex. During rapid depression and elevation of the mandible, the anterior suprahyoid, anterior temporalis, and sternocleidomastoid muscles were myoelectrically active 56%, 73%, and 71% of the time, respectively, and myomechanically active 42%, 59%, and 57% of the time, respectively. Over a follow-up period of 12 months, the studied mandibular motions did not cause injury to the dentitions and temporomandibular joint.     

Levels of lipid peroxides and antioxidants in smokers and nonsmokers

BACKGROUND AND OBJECTIVE: The aim of the study was to evaluate the relationship between cigarette smoking and periodontal damage in terms of the levels of free radicals and antioxidants. MATERIAL AND METHODS: Thirty-five healthy subjects in the age group 25-56 yr and with chronic moderate inflammatory periodontal disease (attachment loss of 3-4 mm) were selected. All subjects were matched with respect to the clinical parameters plaque index, gingival index and attachment loss. Of the 35 subjects, 25 were smokers (smoking a minimum of 15 cigarettes/day) and 10 were nonsmokers. Smokers were subdivided into three subgroups: group I (10 subjects smoking 15-20 cigarettes/day); group II (10 subjects smoking 21-30 cigarettes/day) and group III (five subjects smoking > 50 cigarettes/day). Gingival tissue (obtained during Modified Widman surgery) and blood samples were collected from each of the subjects and analyzed for the following parameters: lipid peroxide, superoxide dismutase, catalase, glutathione and total thiol. RESULTS: The level of lipid peroxide was lowest in nonsmokers (2.242 +/- 0.775 in tissue and 1.352 +/- 0.414 in blood) and highest in smokers smoking > 50 cigarettes/day (6.81 +/- 1.971 in tissue and 4.96 +/- 0.890 in blood), both in tissue and in blood. The increase was statistically significant in all groups, except in tissue of group I smokers. Catalase showed a similar trend, where the levels increased from 0.245 +/- 0.043 in controls to 0.610 +/- 0.076 in group III smokers for tissue, and from 0.231 +/- 0.040 in controls to 0.568 +/- 0.104 in group III smokers for blood. The increase was statistically significant for all groups. Total thiol levels were also higher in smokers than in controls (0.222 +/- 0.050 in controls vs. 0.480 +/- 0.072 in group III smokers in tissue; 0.297 +/- 0.078 in controls vs. 0.617 +/- 0.042 in group III smokers in blood). Except for group I in both tissue and blood, the increase was statistically significant. The superoxide dismutase (SOD) level was higher in nonsmokers (2.406 +/- 0.477 in tissue and 2.611 +/- 0.508 in blood) than in group III smokers (1.072 +/- 0.367 in tissue and 0.938 +/- 0.367 in blood), both in tissue and in blood, but this was significant only in the case of blood and for group III smokers in tissue. The glutathione level in tissue was consistently lower in smokers than in controls, showing a decrease from 121.208 +/- 37.367 in controls to 46.426 +/- 14.750 in group III smokers, but the decrease was not significant in group I smokers. In the case of blood, the glutathione level dropped from 262.074 +/- 68.751 in controls to 154.242 +/- 51.721 in group III smokers, but was statistically significant only for group III smokers. CONCLUSION: The study results show that smoking increases the level of free radicals in periodontal tissues, which in turn may be responsible for the destruction seen in periodontal diseases.     

Analysis of arylsulfatases A and B, acid phosphatase, lactate dehydrogenase, and aspartate transaminase in chronic periapical lesions of endodontic origin

Attempts were made to detect and measure the activities of arylsulfatases. A&B acid phosphatase, lactate dehydrogenase, and glutamate oxaloacetate transaminase (aspartate transaminase) enzymes in human chronic lesions of endodontic origin. Thirteen periapical lesions of endodontic origin and 11 noninflamed control periapical tissues were obtained. The specimens were carried to the laboratory on liquid nitrogen and kept at -70 degrees C. Samples were thawed, homogenized, and then assayed for enzyme activities. The specific activities of arylsulfatase A (nmol/hr/mg protein) were 55.0+/-10.7 (chronic lesions) vs. 3.4+/-2.2 (controls) (p < 0.01). Arylsulfatase B specific activities (nmol/hr/mg protein) were 50.3+/-6.4 (chronic lesions) vs 91.8+/-18.4 (controls). Total acid phosphatase activities (mU/mg protein) were 45.8+/-6.6 (chronic lesions) vs. 26.8+/-3.1 (controls). Lactate dehydrogenase activities (Berger-Broida units/mg protein) of the chronic periapical lesions were significantly higher than the control group (362+/-63.2) vs. (140+/-46.0) (p < 0.05). There was no significant difference between the specific activities of aspartate transaminase in chronic lesions and the control group (68.0+/-14.5) vs. (53.0+/-10.4) mU/mg protein).     

Expression profile of matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs in mature human odontoblasts and pulp tissue

Previous studies have demonstrated that (at least) matrix metalloproteinase (MMP)-2, -8, -9, -14 and -20 are expressed by human odontoblasts. Here, we analysed the expression of 19 MMPs and their specific tissue inhibitors (TIMP)-1, -2 and -3) -1, -2 and -3 in mature human odontoblasts and pulp tissue. Since MMP-20 is almost exclusively expressed by the dentin-pulp complex cells, we further analysed the effect of transforming growth factor (TGF)-beta1 and bone morphogenetic protein (BMPs)-2 on its expression. Matrix metalloproteinase-9 served as a positive control for growth factor responsiveness. It was found that MMP-1, -2, -9, -10, -11, -13, -14, -15, -16, -17, -19, -20 and -23, in addition to TIMP-1, -2 and -3 were expressed by both odontoblasts and pulp tissue. Neither MMP-3 nor MMP-12 were expressed in odontoblasts or pulp tissue, and MMP-7, -8, -24 and -25 were expressed only in the odontoblasts; MMP-2, -10, -11, -14 and -20 were expressed more abundantly by odontoblasts, whereas pulp tissue expressed more MMP-13 and MMP-17. Transforming growth factor-beta1 (1 ng ml(-1)) and BMP-2 (100 ng ml(-1)) did not markedly affect MMP-20 mRNA expression. In contrast, TGF-beta1 alone and with BMP-2 significantly upregulated MMP-9 mRNA by 2.4-fold and by 2.6-fold, respectively, in odontoblasts, while in pulp tissue no effects could be detected. The wide-scale expression of MMPs and TIMPs by mature human odontoblasts and pulp tissue suggests that they may participate in dentin matrix organization prior to mineralization, and that growth factors may further control dentin matrix modeling by differentially regulating individual MMPs.     

Identification and regulation of K+ and Cl- channels in human parotid acinar cells.

The properties of K+ channels in these cells were studied using patch-clamp methods. Two channels, with conductances of 165+/-13 pS (n=6) and 30+/-1 pS (n=3), were identified in single-channel experiments. In cell-attached patches the reversal potentials were -67+/-8 and -74+/-2 mV for the large and small conductance channel, respectively, suggesting that both channels are K+-selective. The large conductance channel was also shown to be K+-selective in inside-out patches. The open probability (P(o)) of this channel was increased at depolarizing potentials and by increasing intracellular Ca2+ concentration ([Ca2+]i). These properties suggest that the large conductance channel is a 'maxi' Ca2+-activated K+ channel (BK(Ca)). The small conductance channel was not observed in inside-out patches. Carbachol (CCh; 10(-5) M) activated the BK(Ca) channel, but not the small conductance channel, in cell-attached patches. CCh also caused a dose-dependent increase in [Ca2+]i measured by fura-2 in microspectrofluorimetric studies, with a half-maximal response at approximately 3x10(-6) M. Neither isoproterenol (10(-5) M) nor substance P (10(-6) M) affected K+-channel activity or [Ca2+]i. In whole-cell experiments, CCh caused an increase in outward current. Charybdotoxin (10(-7) M), a BK(Ca) blocker, inhibited a large component of the CCh-induced current. A large component of the charybdotoxin-insensitive current may be carried by Ca2+-activated Cl- channels, which were also observed in human parotid acinar cells. The results indicate that BK(Ca) channels make a significant contribution to the whole-cell conductance in human parotid acinar cells.     

Longitudinal scintigraphic study of parotid and submandibular gland function after total body irradiation in children and adolescents

OBJECTIVE: Total body irradiation (TBI) and cyclophosphamide (CY) during allogeneic stem cell transplantation (ASCT) cause salivary gland dysfunction in children. The aim of this investigation was to study the scintigraphic functional changes over time of the parotid and submandibular glands in children and young adults one year after treatment with CY and TBI at ASCT. METHODS: Salivary gland scintigraphy (SGS) was performed before ASCT, and 3-6 months and 12 months after ASCT. The three male patients who fulfilled the scintigraphic study had a mean age (+/- SD) of 17.3 +/- 9.8 years at ASCT. RESULTS: The parotid secretion capacity (SPar) was 83.5 +/- 3.2% before ASCT and 48.5 +/- 25.8% during the next 3-6 months (P < 0.05). The SPar did not increase (48.1 +/- 12.4%) during the rest of the first year after ASCT. The submandibular emptying capacity (SSub) was 91.3 +/- 12.9% before ASCT and 35.4 +/- 2.3% after 3-6 months (P < 0.05). The SSub was 87.9 +/- 17.9% one year after ASCT. CONCLUSIONS: The parotid glands were more sensitive to irradiation since they did not recover lost capacity to secrete saliva, while the submandibular glands recovered the secretion capacity at the one-year follow-up.     

Enamel demineralization in primary and permanent teeth

Although enamel demineralization is important for our understanding of caries formation, no consensus has been reached regarding the possible differences in susceptibility of primary and permanent enamel. We used the constant composition (CC) technique to investigate the acid-induced demineralization of these tissues at a relative undersaturation with respect to hydroxyapatite (HAP) of 0.902, pH = 4.5, and ionic strength = 0.15 mol L(-1). The demineralization rates showed significant differences, primary enamel having the greater susceptibility to dissolution during an initial linear stage: 1.5 +/- 0.5 x 10(-10) mol mm(-2) min(-1) compared with 2.6 +/- 0.5 x 10(-11) mol mm(-2) min(-1) for permanent enamel. During the reactions, we observed nanosized crystallites which attached to the enamel surfaces or escaped into the bulk solution. These nanosized crystallites were kinetically protected against further dissolution, even though the solutions remained undersaturated. It is hypothesized that they may contribute to the remarkable mechanical and dynamic characteristics of enamel.     

The bonding area of intra- and extra-coronal tooth preparations

PURPOSE: To assess the accuracy of preparation surface area measurements (mm2) using the Cerec digital mouth camera in vitro and to analyze a collection of 514 Cerec camera in vivo optical impressions of preparations from 274 patients according to the size of preparation/bonding area (mm2) METHODS: The surface area (mm2) of model preparations with known dimensions namely of one occlusal (1) and one mesio-occluso-distal (2) cavity as well as of one central incisor (3) and one molar (4) crown preparation was calculated from linear (a) design dimensions, (b) slide-gauge and (c) coordinate-measuring-machine data as benchmark measurements and from repeated (n=10) (d) laser-scan (control), (e) Cerec-camera mounted on a support, (f) handheld Cerec-camera measurements. Data of (d), (e) and (f) was statistically analyzed. From a collection of data sets clinically recorded with the Cerec camera, the surface areas of 514 preparations from 274 patients were analyzed according to the type of tooth and type of preparation. RESULTS: Occlusal cavity mm2 data 1(d) 48 +/- 0.4, 1(e) 48 +/- 0.2, 1(f) 48 +/- 0.6 and mod cavity mm2 data 2(d) 137 +/- 2, 2(e) 138 +/- 1, 2(f) 138 +/- 4 did not differ between (d), (e) and (f) (P> 0.05) confirming the hypothesis for inlay cavities. Incisor crown preparation mm2 data 3(d) 82+0.4 differed (P< 0.001) from 3(e) 85 +/- 0.2 and 3(f) 85 +/- 0.6 as well as molar crown preparation mm2 data 4(d) 133 +/- 0.6 differed by 3.5% (P< 0.001) from 4(e) 137 +/- 0.4 and 4f) 138 +/- 1. Clinical cavity and crown preparation area data obtained from in vivo Cerec camera recordings differentiated between type of tooth and type of cavity. 2D data of "classic", "reduced" and "endo" type crown preparations did not differentiate clearly.     

Relationship between Candida and nocturnal denture wear: quantitative study

The purpose of this study was to evaluate the relationship between Candida and denture wear during the night. Twenty-four edentulous volunteers were randomly divided into two groups. Group I (GI, n = 11) was composed of volunteers who wore their complete dentures day and night and Group II (GII, n = 13) was composed of volunteers who wore their complete dentures only during the day. Three examination periods were performed for both groups. In GI, the first examination (A) was carried out after overnight denture wearing. Subsequent examinations were conducted after one (B) and seven nights (C) without denture use during sleep. In GII, the first (A) was done without previous use during sleep, and the following were carried out after one (B) and seven nights (C) of overnight denture wearing. Total unstimulated saliva was collected in a sterile container and cultured in duplicate inside Petri dishes. The values of colony forming units (CFU mL(-1) +/- s.d.) were obtained: GI A - 10.1 x 10(3) +/- 1.2 x 10(4), B - 2.0 x 10(3) +/- 2.6 x 10(3), and C - 2.6 x 10(3) +/- 5.9 x 10(3) and GII: A - 0.4 x 10(3) +/- 0.6 x 10(3), B - 9.4 x 10(3) +/- 17.7 x 10(3) and C - 6.3 x 10(3) +/- 15.3 x 10(3). The mean counts for Candida sp. were expressed as log (CFU + 1) mL(-1) and statistical significance of differences among groups was tested by anova (alpha = 0.05). Multiple comparisons were performed according to Bonferroni test and indicated significant differences between A-B and A-C, but not between B and C for both groups. It was concluded that there is a significant relationship between continuous denture wear and Candida sp.     

Comparison of the number and diameter of dentinal tubules in human and bovine dentine by scanning electron microscopic investigation

Detailed information on dentine structure is essential for interpreting data from investigations on dentine-adhesive materials. The purpose here was to compare the number and diameter of dentinal tubules at similarly prepared surfaces of bovine permanent central incisors and human deciduous and third molars. In bovine teeth, crowns and roots were used; in human samples only the crowns were investigated. Tubule density in the middle layer was higher in bovine root (BR) dentine (number of tubules per mm(2)+/-SD: 23, 760+/-2453) than in human deciduous (HD) (18,243+/-3845), human permanent (HP) (18,781+/-5855), and bovine coronal (BC) (17, 310+/-2140) dentine. The corresponding values for the deep layer were 23,738+/-4457 (BR), 24,162+/-5338 (HD), 21,343+/-7290 (HP), and 20,980+/-4198 (BC). No significant differences were found for the number of dentinal tubules in bovine coronal dentine compared to the dentine of human deciduous and permanent molars. The mean diameter of bovine dentinal tubules was slightly, but not significantly, higher than in human dentine (middle layer/deep layer+/-SD): BC, 2. 85 microm+/-0.18/3.50 microm+/-0.33; BR, 3.10 microm+/-0.33/3.23 microm+/-0.30; HD, 2.55 microm+/-0.16/2.82 microm+/-0.28; HP, 2.65 microm+/-0.19/2.90 microm+/-0.22. These findings demonstrate that corresponding coronal dentine layers of human deciduous and permanent molars, and of bovine central incisors, are not significantly different in their number of tubules per mm(2) and their tubule diameter, whereas tubule density in bovine root dentine is significantly higher. These results suggest that provided standardized preparations are used, bovine incisor crown dentine is a suitable substitute for human molar dentine in adhesion studies.     

Variability of the diameter and taper of size #30, 0.04 gutta-percha cones

The purpose of this investigation was to examine variability of gutta-percha (GP) cone tip diameter (D(0)) and taper among five different brands of #30, 0.04 GP cones (n = 15/brand). Mean percent D(0) difference from the manufacturer's reported (nominal) diameter of Maillefer (-15.42 +/- 7.16%) and Lexicon (-12.76 +/- 4.98%) were significantly different (p < or = 0.05) from Maxima (3.18 +/- 7.06%), Diadent (3.62 +/- 11.37%), and K(3) (7.27 +/- 7.84%), which were not significantly different from each other but exhibited diameters larger than the nominal diameter as indicated by positive values. Mean taper percent difference of Maxima (-3.00 +/- 3.80%) was significantly different (p < or = 0.05) from Lexicon (3.67 +/- 3.64%) and Maillefer (6.67 +/- 3.49%), with comparisons to Diadent (-0.17 +/- 6.37%) and K(3) (1.50 +/- 6.93%) not significantly different (p > 0.05) from each other or any other brand. Based on the evidence, there is significant variability between GP cone brands for both diameter and taper, with Maxima and Diadent, respectively, exhibiting the smallest mean difference from manufacturer's nominal tip diameter and taper. However, the high standard deviation values associated with most of the diameter and taper differences from nominal values also suggest high variability within individual brands.     

Growth factor levels in platelet-rich plasma and correlations with donor age, sex, and platelet count.

INTRODUCTION: Platelet-rich plasma contains autologous thrombocyte growth factors and might be promising for acceleration of dentoalveolar bone regeneration. In this study, it was analysed for platelet counts and growth factor concentrations. MATERIAL AND METHOD: Platelet-rich plasma was isolated by discontinuous cell separation from 158 healthy men and 55 women aged 17-62 years. One hundred and fifteen specimens (stratified for age and gender of the donor) were analysed for growth factor concentrations and platelet count. RESULTS: The platelet count in platelet-rich plasma (1,407,640+/-320,100/microl) was 5 times higher than in donor blood (266,040+/-60,530/microl). Platelet-derived growth factor AB (117+/-63 ng/ml), transforming growth factor (TGF) beta -1 (169+/-84 ng/ml), and insulin-like growth factor (IGF) I (84+/-23 ng/ml) were found in large amounts, while platelet-derived growth factor (PDGF) BB (10+/-8 ng/ml) and transforming growth factor beta -2 (0.4+/-0.3 ng/ml) were found in small amounts only. The growth factor content was not well correlated with the platelet count in whole blood nor with the platelet-rich plasma (r(p)=0.35). No influence of gender or age on platelet count or growth factor concentrations was discovered (except IGF-I). CONCLUSIONS: While there was substantial variation in the growth factor content of platelet-rich plasma, the factors influencing this are still worthy of further investigation. Furthermore, a technique whereby the growth factor content could be rapidly assessed in platelet-rich plasma may be of therapeutic benefit.     

Marginal and internal fit of all-ceramic CAD/CAM crown-copings on chamfer preparations

Evaluation of the marginal and internal fit of all-ceramic molar crown-copings hypothesizing that Computer Aided Design/Computer Aided Manufacturing (CAD/CAM) fabrication shows the same accuracy of fit as conventional techniques. A set of six individual crown preparations was duplicated 12 times yielding 72 plaster dies. Slip-cast (In-Ceram Zirconia), heat-pressing (Empress II) and CAD/CAM crown-copings (Cerec inLab, DCS, Decim and Procera) were seated on 12 dies each. Marginal and internal gap width was measured in the SEM at 120x magnification. Marginal gap of slip-cast (25 +/- 18 microm) was significantly (P < 0.05) smaller than that of Empress II (44 +/- 23 microm) copings. Procera (17 +/- 16 microm) and Decim (23 +/- 17 microm) did not differ (P > 0.05) from slip-cast (25 +/- 18 microm) but were smaller (P < 0.001/P < 0.01) than Empress II (44 +/- 23 microm) and Cerec inLab (43 +/- 23 microm) (P < 0.001/P < 0.05). DCS (33 +/- 20 microm) did not differ (P > 0.05) from any of the others. The internal mid-orobuccal gap width of Procera (136 +/- 68 microm) was larger (P < 0.001) than that of Decim (81 +/- 30 microm) and slip-cast (94 +/- 84 microm) (P < 0.05) while Empress II (105 +/- 53 microm), DCS (110 +/- 79 microm) and Cerec inLab (114 +/- 58 microm) did not differ significantly (P > 0.05) from Decim, Procera and slip-cast. Internal mesiodistal gap width was similar. The fit of conventional and CAD/CAM all-ceramic molar crown-copings covered the same range of gap width confirming the assumed hypothesis.     

Influence of light energy and power density on the microhardness of two nanohybrid composites

The purpose of this study was to investigate the role of light parameters on nanohybrid composite curing. Two nanohybrid resins were cured by two light-emitting diode (LED) devices and by one quartz-tungsten-halogen (QTH) device using different combinations of energy density and power density (8 J cm(-2) and 400 mW cm(-2); 8 J cm(-2) and 1,000 mW cm(-2); 16 J cm(-2) and 400 mW cm(-2); and 16 J cm(-2)-1,000 mW cm(-2)). The effects of these combinations on polymerization were assessed by measuring the Vickers microhardness. Data differed for the two composites and varied according to the light parameters and the nature of the curing device. For both resins, an energy density of 16 J cm(-2) yielded the best microhardness values at both the top and the bottom of the sample, independently of the power density. When using a lower energy density of 8 J cm(-2), a modulated power density was required to achieve proper curing at the bottom of the sample: 8 J cm(-2) and 400 mW cm(-2) induced greater values at the bottom surface. At an energy density of 16 J cm(-2), the power density was not relevant (no significant differences were found between 400 and 1,000 mW cm(-2)), except when the emission spectra of the light-curing units (LCUs) did not match exactly with the absorption spectra of the photoinitators included in the resins (greatest values with 16 J cm(-2) and 1,000 mW cm(-2)). These results suggest that above a certain energy density threshold, the power density may not significantly influence the polymerization kinetics.     

The role of iNOS and PHOX in periapical bone resorption

Nitric oxide (NO) and reactive oxygen species (ROS) are key molecules in resistance to pathogens. Little is known about their role in pathogenesis of periapical lesions. To address this issue, we induced periapical lesions in mice lacking nitric oxide synthase (iNOS(-/-)) or phagocyte oxidase (PHOX(-/-)). iNOS(-/-) mice expressed higher levels of IL-1β, TNF-α, RANK, RANKL, and MCP-1 than C57BL/6 and PHOX(-/-). Apical thickening of the periodontal ligament was also greater in iNOS(-/-) compared with other groups. Interestingly, ROS production did not interfere in periapical lesion progression, but seemed to be essential for the appearance of multinucleated TRAP-positive cells. Thus, periapical lesion progression in iNOS(-/-) was associated with an imbalance of pro-inflammatory cytokines (IL-1β and TNF-α), bone-resorptive modulators (RANK and RANKL), and MCP-1. We conclude that NO, but not ROS, controls progression of bone resorption in a murine experimental model of apical periodontitis.     

H3 and H3.3 histone mRNA amounts and ratio in oral squamous cell carcinoma and leukoplakia

Histone variants (e.g. H3) play an important role in chromatin structure and gene expression regulation of normal cells. Aims of this study were to: (1) estimate H3 and H3.3 histone mRNA expressions and their ratio in oral squamous cell carcinoma (OSCC) and oral leukoplakia (OL); (2) investigate whether H3 and H3.3 variants could play a role in the pathogenesis of OSCC and OL, also conditionally to HPV infection, age, gender, and main habits (tobacco smoking and alcohol drinking) in human beings studied. Twenty-three cases of OSCC and 20 cases of OL were examined in lesion site (LS) and juxtaposed clinically undamaged site (JUS) by RT-PCR for H3 and H3.3 histone mRNA; 13 healthy oral mucosa samples (HS) were investigated in a single site as controls. HPV DNA presence was investigated in the respective exfoliated oral mucosa cells by nested PCR (nPCR: MY09-MY11/GP5-GP6). The data showed that both H3 and H3.3 histone mRNA crude concentrations are higher in OSCC (LS = 2901 +/- 459 ng of H3; JUS = 2699 +/- 658 ng of H3; LS = 3190 +/- 411 ng of H3.3; JUS = 2596 +/- 755 ng of H3.3) than those in OL (LS = 2095 +/- 349 ng of H3; JUS = 2192 +/- 897 ng of H3; LS = 2076 +/- 911 ng of H3.3; JUS = 1880 +/- 654 ng of H3.3) and in HS (2579 +/- 959 ng of H3; 2300 +/- 758 ng of H3.3), although not reaching any statistical significance. Interestingly, ratio of H3/H3.3 mRNA amounts decrease both in OSCC (0.99) and OL (1.009) vs HS (1.121). No association was found for H3 and H3.3 histone mRNA expressions in OSCC and OL with respect to HPV infection and the social-demographical variables considered (P > 0.2). The overall higher expression of H3.3 in damaged tissues up to the ratio inversion in OSCC especially in HPV+ alcohol drinkers (60.0%) represents the most interesting finding, in consideration of the proven ability of alcohol to act as permeability enhancer of human oral mucosa, to alter the mucosal structure and by this dynamics could favour the penetration through the epithelial layers of HPV.     

Glucocorticoids induced the production and gene expression of IL-1alpha through AP-1 and partially NF-kappaB activation in murine epidermal cells

To investigate the mechanism of the glucocorticoids-induced augmentation of skin response, we have recently reported the modulatory effect of glucocorticoids on the regulation of cytokines production in keratinocytes stimulated with various chemicals in vitro through both NF-kappaB and AP-1 activation. Further to clarify the mechanism in the glucocorticoids-induced augmentation of cytokines production from keratinocytes, we examined the effect of glucocorticoids to keratinocytes without chemical stimulation. Glucocorticoids 10(-4) M inhibited the production of IL-1alpha from Pam 212 cells. However, lower concentration (10(-8)-10(-10) M) of glucocorticoids significantly enhanced the production of IL-1alpha by Pam 212 cells at both the protein and mRNA levels. In contrast, glucocorticoids had no effect on the production of either TNF-alhpa, IL-6, nor GM-CSF by Pam 212 cells cultured for 6 h. Electrophoretic mobility shift assays (EMSA) revealed that 10(-10)-10(-12) M glucocorticoids induced the NF-kappaB activation in Pam 212 cells, however, augmented AP-1 activation by 10(-8)-10(-10) M of glucocorticoids was observed in Pam 212 cells. Furthermore, pyrrolidine dithiocarbamate (PDTC) partially inhibited the IL-1alpha production and completely inhibited NF-kappaB expression by Pam 212 cells. On the other hand, MAP-kinase inhibitors (PD98059, SB202190) completely abrogated not only AP-1 activation but the low concentration glucocorticoids-induced IL-1alpha production. These data indicated that lower concentration of glucocorticoids induced the augmentation of IL-1alpha production from keratinocytes mediated through the AP-1 pathway and partially through NF-kappaB pathway.     

Immune status of oral lichen planus and squamous cell cancer patients-T subgroup cells evaluation in PBL]

The levels of T-subgroup cells for 30 oral lichen planus(LP) and 25 cancers are reported.15 health are constracted.The results are as follows:Health OKT value T(3) 62.8+/-1.81,T(4) 44.4+/-7.34,T(8) 25.5+/-0.71,T(4)/T(8) 1.79+/-0.13;OLP OKT value:T(3) 53.2+/-1.92,T(4) 40.2+/-1.9, T(8)38.61+/-2.2, T(4)/T(8) 1.10+/-0.07,Cancer value 52.9+/-1.9,40.2+/-2.3,36.4+/-2.05,1.17+/-0.09. Both group of patients were compared with health.The level of OKT(3) OKT(4)/OKT(8) was decreased significantly(0.001),but OKT(8) qA increased significantly(0.001).This shows that T cell immune function is decreased in the oral LP and cancer patients.