Intracanal use of heated rinsing solutions: A pilot study.

OBJECTIVE: The tissue-dissolving and bactericidal activity of sodium hypochlorite (NaOCl) can be increased by warming the NaOCl solution without concurrently increasing its toxicity. The present study was set up to determine if and to what extent a heated liquid reaches the apical region. METHOD AND MATERIALS: A temperature sensor was introduced from the apical aspect into a human canine 22 mm in length prepared to size 40.04. At 37°C in the incubator the canal was irrigated with water 10 times each at temperatures of 10°C, 21°C, 45°C, 60°C, and 37°C (control group). The apical temperature curve was recorded with a one-second resolution from the time the irrigation started until at least 2 minutes after its end. RESULTS: None of the measurements yielded the same temperature in the apical region as that of the coronally introduced liquid. At 60°C, a maximum value of 52.2°C ±â€¯1.39°C, and at 10°C, a minimum value of 16.09°C ±â€¯0.39°C, was achieved apically. At 1 minute after the end of active rinse cycle, the temperature at the apical probe differed only 4.8°C to 0.9°C ±â€¯1.41°C from the initial value (about 37°C). Only with the cold 10°C solution was the temperature difference higher, at 7.5°C ±â€¯2.14°C. CONCLUSION: The benefit of heating irrigants accrues primarily during the period of active rinsing; immediately after the end of the rinsing cycle, body temperature is reached again. A positive aspect to be noted is that an irrigant stored at room temperature is quickly warmed to 37°C in the root canal by the temperature of the body.

Investigation of the oral status and microorganisms in children with phenylketonuria and type 1 diabetes.

OBJECTIVE: The aim of this study was to investigate the oral parameters that influence the caries risk and risk of developing periodontal disease in children with phenylketonuria (PKU) and type 1 diabetes compared to healthy children. MATERIAL AND METHODS: Two hundred and thirty-eight children between the ages of 3 and 18 years were recruited in the PKU, diabetes and healthy group. The decayed, missing and filled surfaces (dmfs/DMFS) index, papillary bleeding index (PBI) and the Silness & Löe Index were assessed. Quantitative real-time polymerase chain reaction (PCR) was used for the detection of Streptococcus mutans (Sm), Lactobacillus casei (Lca), Lactobacillus species (Lac), Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg) and Tannerella forsythensis (Tf). RESULTS: A statistically significant difference in the dmfs index value was found between the three groups. The mean dmfs index value for the PKU children (4.18) was found to be relatively high. Comparing the three groups, diabetics showed statistically significant higher values for the Silness and Löe Index. Comparing the diabetics to just the healthy children, the diabetics revealed a small statistically significant difference in the PBI score. A statistically significant difference was found between Lac, Lca and Pg in the three groups. Counts of Lac were the lowest in the PKU children. The diabetics showed the highest counts of Lca but lowest for Pg. CONCLUSIONS: Comparing the three groups, children with PKU revealed a higher caries experience in their primary dentition. While the diabetic children showed a lower one in their primary dentition, they were found to possess a slightly higher risk of developing periodontal disease. CLINICAL RELEVANCE: It is proposed that both groups of child patients be encouraged to seek early dental advice and be incorporated in a meticulous prevention programme.

Nuclear expression of p27(Kip1) is associated with in vivo differentiation of adult human odontoblasts.

INTRODUCTION: Odontoblasts are terminally differentiated cells of ectomesenchymal origin that produce the dentin. Differentiated odontoblasts cannot be identified yet by a single phenotypic marker protein; therefore, a combination of markers is currently used. Up-regulation of the cyclin-dependent kinase inhibitor p27(Kip1) has been associated with exit from the cell cycle and terminal differentiation of mammalian cells. Immunoreactivity for p27(Kip1) protein was shown in many adult mouse tissues, but no information is available on the expression of p27(Kip1) in mammalian dental pulp. METHODS: Healthy and carious adult human molars with reparative dentin formation were decalcified, cryoprotected, frozen embedded, and frozen sectioned. The expression of p27(Kip1) and nestin in cells of adult human dental pulp was analyzed by immunohistochemistry using free floating sections. RESULTS: p27(Kip1) showed strong nuclear expression in many differentiated human molar odontoblasts at the odontoblastic layer. Most cells of the cell-rich zone displayed low levels of p27(Kip1) despite the fact that preodontoblasts localized in the cell-rich zone of the subodontoblastic layer have been identified as quiescent cells. The nuclear expression of p27(Kip1) in stromal cells of the dental pulp was variable, indicating that subpopulations of these cells were in distinct states of differentiation. Odontoblasts generating reparative dentin showed comparable nuclear expression of p27(Kip1) in comparison with odontoblasts synthesizing primary/secondary dentin. This result indicates that odontoblasts synthesizing primary/secondary or reparative dentin exhibit a similar differentiation status. CONCLUSIONS: Our findings show that increased expression of nuclear p27(Kip1) occurred during differentiation from preodontoblasts to odontoblasts in adult healthy and carious molars. p27(Kip1) can be used as a novel nuclear marker protein for differentiated human odontoblasts in vivo.

Transcription factor CREB is phosphorylated in human molar odontoblasts and cementoblasts in vivo.

A wide variety of stimuli can trigger activation of the transcription factor CREB (cAMP-responsive element binding protein), pointing toward a central role for CREB in the integration of various signaling inputs. No data are available on the expression and phosphorylation of CREB in mammalian teeth. Using immunohistochemical analysis of free-floating sections, we show here that CREB was strongly expressed and phosphorylated at Ser-133 within the nucleus of a subpopulation of adult human molar odontoblasts. Many dental pulp stromal cells and periodontal ligament fibroblasts expressed CREB and showed phosphorylation of CREB at Ser-133. In addition, cementoblasts displayed nuclear expression and phosphorylation of CREB at Ser-133. The epithelial rests of Malassez revealed strong nuclear expression of CREB, but phosphorylation at Ser-133 was variable. Our results provide the first evidence that the constitutively phosphorylated transcription factor CREB is involved in the biomineralization process of adult human molar odontoblasts and cementoblasts.

Bacterial viability on surface-modified resin-based dental restorative materials.

UNLABELLED: The purpose of the present investigation was to investigate the viability of early colonizers on the surfaces of resin-based dental restorative materials modified with low-surface tension active agents in comparison with the unmodified material. A novel polymeric sorption material, loaded with two low-surface tension γ(L) active agents (hydroxyfunctional polydimethylsiloxane and polydimethylsiloxane) or a polymerizable active agent (silicone polyether acrylate), was used to modify commonly formulated experimental dental resin composites. The non-modified resin was used as the standard (ST). The viability of Actinomyces naeslundii, Actinomyces viscosus, Streptococcus mitis, Streptococcus oralis, and Streptococcus sanguinis on water-stored, polished, and human saliva pellicle-coated specimens was determined using a fluorescence microscope after 8 and 24h. Total, vital, and non-vital cells were calculated from the microscopic images by counting pixels per colour. Means, standard deviations, univariate ANOVA and multiple comparisons with post hoc Scheffé's tests were calculated. t-Test was done to compare 8-h and 24-h bacteria counts. For all tests p<0.05 was chosen. NULL HYPOTHESIS: the test materials and the standard did not differ either in the total bacterial counts or in the respective bacterium's viability after 8 or 24h. The test materials modified with the silicone polyether acrylate showed lower total bacteria count after 8 or 24h than ST. But all test materials had significantly fewer vital cells after 8 or 24h compared to ST. The contact angle did not influence bacterial adhesion, but low total SFE and a low polar term of SFE resulted in fewer bacteria. The material's chemistry also affected the total and vital cell counts. Different bacteria viabilities needed to be explored to obtain relevant information regarding bacterial adhesion on dental composite resins. The novel sorption material loaded with low γ(L) active agents or with a low γ(L) polymerizable silicone polyether acrylate used to modify the chemistry of the test materials was appropriate to reduce bacterial adhesion or cell viability, respectively.

Histone deacetylases 2 and 9 are coexpressed and nuclear localized in human molar odontoblasts in vivo.

Histone deacetylases (HDACs) are components of nuclear multiprotein complexes that deacetylate histones and perform important roles in repression of transcription.Using specific rabbit mAbs, we analyzed by immune histochemistry and confocal immunofluorescence analysis the expression and subcellular localization of HDAC1­4 and HDAC9 in sections of adult human third molars. HDAC2 and HDAC9 were expressed in some pulpal cells and strongly expressed in the majority of mature odontoblasts.In contrast, only weak expression of HDAC1, HDAC3 and HDAC4 was observed. Confocal immunofluorescence analysis together with the DNA stain DRAQ5 revealed that HDAC2 and HDAC9 were coexpressed within the odontoblast nucleus, but localized to distinct subnuclear structures.In contrast to the current point of view, HDAC2 is strongly expressed in a terminally differentiated cell type.Our results imply that class I and II HDACs are involved in the transcriptional regulation of human odontoblasts in vivo.

Therapies most frequently used for the management of bruxism by a sample of German dentists.

STATEMENT OF PROBLEM: At present, there is little information available on how practicing dentists manage bruxism patients with respect to conservative, reversible techniques as compared to irreversible techniques. PURPOSE: The purpose of this study was to determine the most commonly applied therapies used for the management of bruxism by German general dentists (GDs) and dental specialists. In addition, efforts were made to gather information on the knowledge and opinion of GDs and specialists regarding the role of occlusal interferences, in particular, on the development of sleep bruxism. MATERIAL AND METHODS: A 13-item questionnaire was developed and mailed to all active members of the statutory dental insurance providers of the German North Rhine (n=5500; 2006 roster) and the German Westphalia-Lippe area (n=4984; 2006 roster). Group differences were statistically analyzed using chi-square tests for the qualitative variables and Mann-Whitney U tests for the quantitative variables (α=.05). RESULTS: Occlusal splints were by far the most frequently prescribed therapy for the management of bruxism, followed by relaxation techniques, occlusal equilibration, physiotherapy, and prosthodontic reconstruction. The occlusal stabilization splint with canine protected articulation was the splint type most often prescribed, whereas respondents used unadjusted soft splints for approximately 8% of their bruxism patients. Comparison of the opinions of all responding practicing dentists with that of experts in regard to the statement that "sleep bruxism is caused by occlusal interferences" showed a significant difference between the 2 groups (P=.021). Eighty-five percent of the experts disagreed with this statement, and only 47.7% of the practicing dentists had the same opinion as the experts. CONCLUSIONS: Most practicing dentists seem to concur with current scientific recommendations, and express the opinion that the management of bruxism should predominantly be conservative and reversible; however, the findings of the present survey reveal diverse differences between GDs and dental specialists concerning the most frequently prescribed therapies. Moreover, the discrepancies detected in some areas, such as the use of irreversible techniques or the use of unadjusted soft splints, emphasize the need to more promptly transfer new knowledge in the field of bruxism from researchers to practicing dentists.

Efficacy of a novel pacifier in the prevention of anterior open bite.

PURPOSE: The purpose of this study was to test a novel pacifier (Dentistar) regarding the development of anterior open bite in infants. METHODS: One hundred twenty-nine newborn children were randomly assigned to 2 experimental groups: NUK (N; N =73); and Dentistar (D; N=56. Children (N=42) who did not use a pacifier served as the control (C). At 10- to 26-months old, the children were re-examined (via a blind operator) regarding the existence of an anterior open bite. RESULTS: One hundred twenty-one toddlers (66 females, 55 males) were included in the final analysis (N: N=42; D: N=43; C: N=36). The mean age was 15.9 (±3.9 SD) months. In Group N, 16 children (38%) showed an anterior open bite, 2 (5%) in Group D, and 0 in Group C. The incidence of open bites was significantly less in Groups D and C vs N (chi-square test, P<.001). No significant difference was found between D and C. CONCLUSION: Pacifier use may promote open bites in 16-month-old infants. Compared to a commonly used pacifier, the Dentistar caused almost no anterior open bites and, therefore, can be recommended for children younger than 16 months old.

A new approach to influence contact angle and surface free energy of resin-based dental restorative materials.

The purpose of the present study was to identify novel delivery systems and active agents which increase the water contact angle and reduce the surface free energy when added to resin-based dental restorative materials. Two delivery systems based on zeolite or novel polymeric hollow beads (Poly-Pore), loaded with two low surface tension active agents (hydroxy functional polydimethylsiloxane and polydimethylsiloxane) or a polymerizable active agent (silicone polyether acrylate) were used to modify commonly formulated experimental dental resin composites. The non-modified resin was used as a standard (ST). Flexural strength, flexural modulus, water sorption, solubility, polymerization shrinkage, surface roughness Ra, contact angle θ, total surface free energy γS, and the apolar γSLW, polar γSAB, Lewis acid γS+ and base γS- components, and the active agents surface tensions γL were determined (P<0.05). The active agents did not differ in γL. The modified materials had significantly higher θ but significantly lower γS, γSAB and γS- than the ST. A Poly-Pore/polydimethyl siloxane delivery system yielded the highest θ (110.9±3.5°) acceptable physical properties and the lowest values for γSLW and γS-. Among the modified materials the polymerizable materials containing active agents had the lowest γAB and the highest γS+ and γS-. Although not significant, both of the zeolite delivery systems yielded higher γSLW, γS+ and γS- but lower γSAB than the Poly-Pore delivery systems. Poly-Pore based delivery systems highly loaded with low surface tension active agents were found not to influence the physical properties but to significantly increase the water contact angle and thus reduce surface free energy of dental resin composites.

Physical properties of self-, dual-, and light-cured direct core materials.

The objective of this study is to evaluate flexural strength, flexural modulus, compressive strength, curing temperature, curing depth, volumetric shrinkage, water sorption, and hygroscopic expansion of two self-, three dual-, and three light-curing resin-based core materials. Flexural strength and water sorption were measured according to ISO 4049, flexural modulus, compressive strength, curing temperature, and curing depth according to well-proven, literature-known methods, and the volumetric behavior was determined by the Archimedes' principle. ANOVA was calculated to find differences between the materials' properties, and correlation of water sorption and hygroscopic expansion was analysed according to Pearson (p < 0.05). Clearfil Photo Core demonstrated the highest flexural strength (125 ± 12 MPa) and curing depth (15.2 ± 0.1 mm) and had the highest flexural modulus (≈12.6 ± 1.2 GPa) concertedly with Multicore HB. The best compressive strength was measured for Voco Rebilda SC and Clearfil DC Core Auto (≈260 ± 10 MPa). Encore SuperCure Contrast had the lowest water sorption (11.8 ± 3.3 µg mm(-3)) and hygroscopic expansion (0.0 ± 0.2 vol.%). Clearfil Photo Core and Encore SuperCure Contrast demonstrated the lowest shrinkage (≈2.1 ± 0.1 vol.%). Water sorption and hygroscopic expansion had a very strong positive correlation. The investigated core materials significantly differed in the tested properties. The performance of the materials depended on their formulation, as well as on the respective curing process.

The Ca(2+)-binding protein calretinin is selectively enriched in a subpopulation of the epithelial rests of Malassez.

During tooth development, the inner and outer enamel epithelia fuse by mitotic activity to produce a bilayered epithelial sheath termed Hertwig's epithelial root sheath (HERS). The epithelial rests of Malassez (ERM) are the developmental residues of HERS and remain in the adult periodontal ligament (PDL). Although the cellular regulation of the Ca(2+)-binding proteins parvalbumin, calbindin-D28k, and calretinin has been reported in the inner and outer enamel epithelia during tooth development, an involvement of Ca(2+)-binding proteins in the ERM has not so far been characterized. Among the three Ca(2+)-binding proteins tested (calbindin D28k, parvalbumin, calretinin), we have only been able to detect calretinin in a subpopulation of adult rat molar ERM, by using quantitative immunohistochemical and confocal immunofluorescence techniques. TrkA (a marker for ERM) is present in numerous epithelial cell clusters, whereas calretinin has been localized in the cytosol and perinuclear region of a subpopulation of TrkA-positive cells. We conclude that, in inner and outer enamel epithelial cells, Ca(2+) is regulated by calbindin, parvalbumin, and calretinin during tooth development, whereas in the ERM of adult PDL, Ca(2+) is regulated only by calretinin. The expression of Ca(2+)-binding proteins is restricted in a developmental manner in the ERM.

The masticatory contractile load induced expression and activation of Akt1/PKBalpha in muscle fibers at the myotendinous junction within muscle-tendon-bone unit.

The cell specific detection of enzyme activation in response to the physiological contractile load within muscle-tendon-bone unit is essential for understanding of the mechanical forces transmission from muscle cells via tendon to the bone. The hypothesis that the physiological mechanical loading regulates activation of Akt1/PKBalpha at Thr308 and at Ser473 in muscle fibers within muscle-tendon-bone unit was tested using quantitative immunohistochemistry, confocal double fluorescence analysis, and immunoblot analysis. In comparison to the staining intensities in peripheral regions of the muscle fibers, Akt1/PKBalpha was detected with a higher staining intensity in muscle fibers at the myotendinous junction (MTJ) areas. In muscle fibers at the MTJ areas, Akt1/PKBalpha is dually phosphorylated at Thr308 and Ser473. The immunohistochemical results were confirmed by immunoblot analysis. We conclude that contractile load generated by masticatory muscles induces local domain-dependent expression of Akt1/PKBalpha as well as activation by dually phosphorylation at Thr308 and Ser473 in muscle fibers at the MTJ areas within muscle-tendon-bone unit.

Effect of Energy Density on the Physical Properties of Resin-Based Restorative Materials when Polymerized with Quartz-Tungsten Halogen or LED-Light.

OBJECTIVES: The purpose of this study was to evaluate flexural strengths, moduli, and maximum deflection of Clearfil AP-X (APX) and Ceram-X Mono (CXM) when cured with a quartz-tungsten halogen (QTH) or an LED-light (LED). METHODS: Specimens were made according to ISO 4049 and cured with QTH or LED for 10, 20 or 60s. Flexural strength, modulus, and deflection were determined after 24 h water storage at 37 degrees C and after thermocycling. Statistical significance was P<.05. RESULTS: Flexural strength did not depend on energy density or curing light and was significantly higher for APX than for CXM but decreased after thermocycling for both materials. Modulus and deflection depended on energy density. Modulus was significantly higher for APX than for CXM and increased for APX but decreased for CXM after thermocycling. Deflection decreased with increasing energy density and decreased after thermocycling. Though energy density did not influence flexural strength, it positively correlated with flexural modulus and negatively with maximum deflection. CONCLUSIONS: Energy density did not influence flexural strength but modulus and deflection. Thermocycling affected all material properties. The LED was as effective as the QTH.

Correlation between stress, stress-coping and current sleep bruxism.

BACKGROUND: Stress is discussed as a potential factor in the development of sleep bruxism (SB). The aim of this study was to investigate whether specific stress-factors correlate with SB-activity. METHODS: Sixty-nine subjects, of which 48 were SB-patients, completed three German questionnaires assessing different stress-parameters and stress-coping-strategies: Short questionnaire for recognition of stress-factors (Kurzer Fragebogen zur Erfassung von Belastungen, KFB), Questionnaire for recuperation and strain (Erholungs-Belastungs-Fragebogen, EBF-24 A/3) and the stress-coping questionnaire (Stressverarbeitungsfragebogen-78, SVF-78). The diagnosis of SB was based on the clinical criteria of the American Academy of Sleep Medicine (AASM). The degree of SB-activity was measured by the Bruxcore-Bruxism-Monitoring-Device (BBMD, Bruxcore, Boston, USA), worn for five consecutive nights and analyzed using a computer-based method. Non-parametric Spearman correlation coefficients, rho, were calculated between the psychometric data and the amount of SB-activity measured by a pixel score of the BBMD. RESULTS: Significant correlations were found for 'daily problems' (r = 0.461, p < 0.01), 'trouble at work' (r = 0.293), 'fatigue' (r = 0.288), 'physical problems' (r = 0.288) and the coping-strategy 'escape' (r = 0.295) (all p < 0.05). CONCLUSIONS: Within the limitations of this study it could be shown that subjects with high SB-activity tend to feel more stressed at work and in their daily life, which in turn might influence their physical state. These subjects also seem to deal with stress in a negative way. However, due to the rather low to almost moderate correlation coefficients and the descriptive character of the study, further investigations are necessary to examine a possible causal relationship.

Impact of replacing Bis-GMA and TEGDMA by other commercially available monomers on the properties of resin-based composites.

PURPOSE: To evaluate important material properties of six experimental resin-based restorative materials (EXP) with systematically modified resin matrices using conventional and alternative monomers in comparison with an experimental standard (ST). MATERIALS AND METHODS: Commercially available monomers were selected according to their molecular weight, functionality, viscosity, and polymerization shrinkage. ST, 71wt% filler, matrix UDMA/Bis-GMA/TTEGDMA and six EXPs with modified organic matrices but the same filler content were manufactured. Flexural strength, flexural modulus, water sorption, solubility and polymerization shrinkage of all EXPs were measured and compared with the results of ST. RESULTS: ANOVA (p<0.05) revealed significant differences among the materials and all investigated properties. Bis-GMA and UDMA were substituted by alternative monomers without losing flexural strength or modulus. Replacing the diluting monomer TTEGDMA with alternative monomers resulted in increased flexural strength. None of the experimental products with modified matrices showed increased water sorption or solubility but some even performed better than ST. Increased hygroscopic expansion and reduced shrinkage were achieved using a very hydrophilic monomer but no significant differences of water sorption and solubility in comparison with ST were found. CONCLUSION: The results indicated that there are monomers commercially available providing the same or even better properties than conventional matrices.

Effect of exposure time on the color stability of resin-based restorative materials when polymerized with quartz-tungsten halogen and LED light.

The objective of this study was to investigate the effect of exposure time on color stability of resin-based restorative materials when polymerized with quartz-tungsten halogen light (QTH) or light-emitting diode light (LED). Eight samples of Ceram-X Mono, Dyract eXtra, and Tetric EvoCeram each were cured for 10, 20, and 60 s with QTH or LED. The CIE-Lab values (L*, a*, b*) were measured prior to and after performing water storage or a Suntest, and ΔL, Δa, Δb, and ΔE were calculated. Statistical analysis (p < 0.05) showed significant changes of the color values after each of the aging processes as well as between ΔL, Δa, Δb, and ΔE of the materials in dependence of the curing device, exposure time, aging condition, and material formulation. LED performed similarly or even better with 10-s exposure time than QTH with 20 s. No improvement of color stability was achieved with increasing exposure time of 60 s either for LED or for QTH. Exposure time, emission spectrum of the light-curing device, as well as the individual material formulation influence color stability. There is apparently an exposure time above which the individual material formulation, especially type and amount of photoinitiator or synergist, dominate the color stability.

Comparative clinical study of the effectiveness of three different bleaching methods.

OBJECTIVE: The current study assessed the efficacy of three current bleaching methods. METHODS: Seventy-five healthy subjects (45 female; 30 male) with anterior teeth, having a Vita Shade score of A2 or darker, participated in the study. The subjects were randomly assigned to one of three treatment groups: Group A: home-bleaching (illumine Home, 10% carbamide peroxide, trays, overnight, for two weeks), Group B: in-office bleaching (Illumine Office, 15% hydrogen peroxide, trays for 45 minutes, three times over three weeks), Group C: Whitestrips (strips, twice a day, 30 minutes each for two weeks). Following the screening visit, three weeks prior to the baseline examination, all subjects received a dental prophylaxis. The color of the teeth was determined using a colorimeter (ShadeEye NCC) and a custom-made stent at baseline (E0), immediately after completion of the bleaching (E3) and three months after treatment (E4). All subjects received oral hygiene instructions and a toothbrush and toothpaste for oral home care during the study period. The change of tooth color was determined for each treatment regimen between baseline and E3 and baseline and E4 and was statistically analyzed performing the Kruskal Wallis test and the Mann-Whitney-U test. The significance level was set atp < 0.01. RESULTS: The dropout rate was 0%. Mean (SD) deltaE* (overall color change) from baseline to immediately after treatment was 6.57 (2.13) for Group A, 5.77 (1.72) for Group B and 3.58 (1.57) for Group C. The mean (SD) tooth color change from baseline to three months after treatment deltaE* was: 4.98 (1.34) for Group A, 4.59 (1.42) for Group B and 2.99 (1.39) for Group C. Significant differences were found between home bleaching and Whitestrips, as well as between in-office bleaching and Whitestrips, but not between home-bleaching and in-office bleaching during the same time. CONCLUSION: Using an objective color measurement device, home bleaching and in-office bleaching were found to be superior to Whitestrips. Home bleaching and in-office bleaching were equally efficient for bleaching teeth and maintaining the results for up to three months.

Effect of a 5000 ppm fluoride toothpaste and a 250 ppm fluoride mouth rinse on the demineralisation of dentin surfaces.

BACKGROUND: The purpose of this study was to test the null hypothesis that there is no difference between the effect of (1) a 5000 ppm fluoride toothpaste, and (2) a 250 ppm fluoride mouth rinse on demineralized human dentin surfaces, against the alternative hypothesis of a difference. FINDINGS: Dentin specimens were obtained from the cervical regions of 45 extracted human third molars. Half the surface of each specimen was sealed with a self-etching adhesive system and served as the reference surface. The dentin specimens were randomly assigned to one of the three groups, 5000 ppm fluoride toothpaste (Duraphat), 250 ppm fluoride mouth rinse (Meridol) and distilled water (negative control).An intraoral appliance was made for one volunteer. In each test cycle, 15 specimens were inserted in the appliance and worn for 24 hours a day, over a period of three weeks.Once daily, the appliance was immersed in the agent being tested; either toothpaste slurry, mouth rinse or distilled water for 60 seconds.Demineralization was assessed in terms of lesion depth (microm) and mineral loss (vol. % x microm) by transversal microradiography. Data analysis was accomplished using Kolmogorov-Smirnov test and ANOVA (SPSS 12.0).Statistically significant differences for mineral loss and lesion depth were found between the toothpaste and the mouth rinse as well as between the toothpaste and the control group, but not between the mouth rinse and the control group. CONCLUSION: Within the limitations of this study, the results suggest that treatment of demineralised dentin with a toothpaste containing 5000 ppm fluoride may considerably reduce mineral loss and lesion depth on exposed dentin.

The constitutive activation of extracellular signal-regulated kinase 1 and 2 in periodontal ligament nerve fibers.

BACKGROUND: The extracellular signal-regulated kinases 1 and 2 (ERK1/2) have been implicated in the inflammation-dependent sensitization of nociceptors. Because the periodontal ligament (PDL) contains numerous nociceptors and mechanoceptors, phosphorylation of ERK1/2 was investigated in nerve fibers of the PDL to elucidate the role of constitutive local activation of ERK1/2 in peripheral sensitization. METHODS: Decalcified free-floating sections of rat molars with PDL were incubated using total (t)-ERK1/2 and phosphorylated (p)-ERK1/2 antibodies. For identification of nerve fibers in the PDL, double staining was performed using protein gene product 9.5 (PGP 9.5) with p-ERK1/2. To test whether p-ERK1/2 activated in sensory and mechanoreceptive terminals, double incubations were performed using p-ERK1/2 with calcitonin gene-related peptide (CGRP) and with calretinin. Labeled nerve fibers were quantified by the point-counting method. RESULTS: In cervical, midroot, and apical zones of the PDL, t-ERK1/2- and p-ERK1/2-labeled nerve fibers were found in close association with blood vessels. The p-ERK1/2-labeled free nerve fibers were often detected in cervical and apical areas of the PDL. In nerve fibers of the PDL, p-ERK1/2 was colocalized with PGP 9.5, CGRP, and calretinin. CONCLUSIONS: The perivascular distribution of t-ERK1/2 and p-ERK1/2 in nerve fibers in the PDL is compatible with a role for the constitutive activation of ERK1/2 in the neural regulation of blood vessels in the PDL. The colocalizations of p-ERK1/2 with CGRP and calretinin indicate that ERK1/2 is constitutively activated in a subpopulation of sensory and mechanoreceptive nerve terminals in the PDL.

Long-term survival of Cerec restorations: a 10-year study.

This clinical retrospective study assessed the longevity of CAD-CAM ceramic restorations (Cerec) inserted into the cavities of 95 patients in a private practice in Berlin, Germany. Three hundred and eight ceramic restorations were inserted into cavities in the posterior teeth of 95 patients between 1992 and 1994. One operator placed all restorations in a single sitting. Seventy-four patients, including 226 restorations, returned to the practice for a final examination at the end of 10 years. Reasons for non-attendance include relocation (15), death (2) and personal reasons (4). Again, all examinations were performed by a single examiner, however, not the same dentist who initially treated the patients. Out of the 226 restorations, 39 had been inserted in Class I cavities and 187 in Class II cavities (84 two-surfaces, 103 three or more surfaces). In the latter group, one cusp was replaced in 20 cases and two cusps in three cases. All the restorations were fabricated using Cerec 1 (46 Dicor, 180 Vita Mark II) and cemented adhesively with Vita Cerec Duo Cement in combination with Syntac Classic under a rubber dam. Kaplan-Meier survival analysis was calculated under the following failure-criteria: (1) secondary decay, (2) any kind of loss of the restoration, (3) fracture of the restoration, (4) tooth fracture and (5) marginal gap reaching dentin or base material. For statistical analysis, SPSS 12.0 was used. The survival rate was 94.7% (12 failures) after five years and 85.7% (23 failures) after 10 years. The results of the current study show that the survival rate of Cerec 1 restorations, as applied in this study, are comparable with the survival rates of cast gold restorations.