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.

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.

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.

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.

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.

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 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.

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.

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.

The effect of different bonding techniques on ceramic/ resin shear bond strength.

PURPOSE: To investigate the effect of different adhesives on the shear bond strength between a feldspathic machinable ceramic and a luting resin. MATERIALS AND METHODS: Seven groups of 20 ceramic specimens each were machined from Vita Mark II blocs. Their surfaces were uniformly treated with 1000-grit paper. Group 1 (control) was hydrofluoric-acid etched for 60 s, group 2 abraded with CoJet, and group 3 PyrosilPen-treated and silanized. Groups 4 and 5 were hydrofluoric-acid etched for 60 s and silanized with two experimental silanes. Variolink II was used as the luting resin for groups 1 to 5. Group 6 and 7 were phosphoric-acid etched for 15 s. Then group 6 was treated with Nexus and group 7 with the Panavia F 2.0 system. All specimens were stored dry for 24 h at 37 degrees C. Shear bond strength was measured prior to and after 5000 thermocycles (TC) between 5 degrees C and 55 degrees C in water. ANOVA was performed with p < or = 0.05. RESULTS: Shear bond strength values 24 h / TC in MPa (SD) were as follows: group 1: 11 (3.0)/ 12 (5.3), group 2: 22 (3.9) / 25 (7.3), group 3: 26 (9.0) / 30 (8.0), group 4: 12 (5.9) / 8 (2.0), group 5: 8 (2.4) / 7 (3.4), group 6: 16 (6.1) / 3 (1.6) and group 7: 16 (8.6) / 16 (4.3). Cojet (24 h, p < or = 0.0007 / TC, p < or = 0.0001) and PyrosilPen (24 h, p < or = 0.0001/ TC, p < or = 0.0001) showed significantly higher bond strength than the control but did not differ significantly from each other. No significant differences between the control and groups 4, 5, 6, and 7 were found. PyrosilPen (p < or = 0.0001) significantly performed best prior to and after TC. Bond strength of experimental silane A (p < or = 0.0499) and Nexus (p < or = 0.0002) significantly decreased after TC. CONCLUSION: Silicoating technology and tribochemistry are fast, trouble-free, and effective surface treatment methods for achieving very good bond strength between feldspathic ceramics and luting resins. Etching with H2F2 can thus be avoided.

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.

In vitro effect of light-emitting diode light polymerization on the color stability of three resin-based restorative materials.

OBJECTIVE: To investigate the color stability of resin-based restorative materials when polymerized with light-emitting diode (LED) curing light in the constant or exponential mode. MATERIAL AND METHODS: Eight specimens of Admira (AD), Compoglass F (CO), and Tetric EvoCeram (TE) constantly cured or exponentially cured with a high-powered LED curing light for 10, 20, or 60 s. The CIE-Lab values (L*, a*, b*) were measured prior to and after performing the water storage or color stability test according to EN ISO 7491 (Suntest). RESULTS: Statistical analysis showed significant changes in the color values after each of the aging processes, as well as between DeltaL, Deltaa, Deltab, and DeltaE of the materials, which were dependent on curing time, mode, and aging condition (p<0.05). CO performed very well during water storage, but AD and TE exceeded the clinically relevant limit DeltaE=1. After the Suntest and 180 d additional water storage, TE showed the highest mean (SD) DeltaE=4.4 (1.1) to 5.4 (1.9). Although AD and CO performed best in the constant mode, they exceeded DeltaE=1. All materials shifted to more red. CONCLUSIONS: The extent of discoloration depended on (a) the curing mode, (b) the curing time, and (c) the aging condition. Not all materials performed clinically acceptably in all tests; TE even showed unacceptable DeltaE>3.3. The optimal curing time was 20 s for both curing modes and all tested materials.

Prion protein (PrP) in human teeth: an unprecedented pointer to PrP's function.

Although prion protein's (PrP) involvement in transmission of degenerative neurological diseases has been subjected to considerable scrutiny, its physiological role is still obscure. The distribution of PrP in dental tissues was investigated using three different methods: immunohistochemistry, cell culture, and scanning electron microscopy. PrP knockout mice were found to have marked anomalies in dentin structure. In human teeth, cementoblasts and odontoblasts showed prominent staining for PrP at levels comparable to those of nerve fibers. Epithelial rests of Malassez, which are remnants of a cell type formerly forming enamel, were also positive. Thus, all PrP-positive cells in human dentition are in some way involved in calcified tissue formation. This suggests a previously undetected function of prion protein in healthy vertebrates as evidenced by an obvious phenotype in PrP knockout mice. Periodontal and pulpal tissue exposed by disease or trauma might represent a clinically relevant entry point for prions incorporated orally and thus a possible mode of infection.

Determination of the performance of various root canal disinfection methods after in situ carriage.

The aim of this study was to compare the antimicrobial performance of the Endox Endodontic System (Lysis Srl, Nova Milanese, Italy), MTAD (Dentsply Tulsa Dental, Tulsa, OK), sodium hypochlorite (NaOCl), and HealOzone (Kavo, Biberach, Germany). Seventy instrumented and initially sterile roots with open accesses and containing a paper point were carried by one volunteer in the oral cavity for 1 week. After removal, samples were taken for microbiological analysis. The root canals were then disinfected with the Endox Endodontic System, MTAD, 3% NaOCl, or HealOzone, and, thereafter, samples were repeated for microbiological analysis. The roots were then sealed and incubated for a further week, after which bacterial growth was again determined. After disinfection, there was a significant decrease in the absolute bacterial count between each disinfection method and the positive control group. There was no statistically significant difference between the NaOCl, MTAD, and HealOzone groups. The Endox device showed the least antibacterial effect with significant differences to MTAD and HealOzone. Bacterial regrowth after 1 week of incubation was detected in all samples of the control group, whereas test groups showed several bacteria-free samples.

Polymerization shrinkage and hygroscopic expansion of contemporary posterior resin-based filling materials--a comparative study.

OBJECTIVES: To investigate the polymerization shrinkage and hygroscopic expansion of contemporary posterior resin-based filling materials. METHODS: The densities of SureFil (SU), CeramXMono (CM), Clearfil AP-X (CF), Solitaire 2 (SO), TetricEvoCeram (TE), and Filtek P60 (FT) were measured using the Archimedes' principle prior to and 15min after curing for 20, 40 and 60s and after 1h, 24h, 7 d, and 30 d storage at 37 degrees C in water. Volumetric changes (DeltaV) in percent after polymerization and after each storage period in water were calculated from the changes of densities. Water sorption and solubility were determined after 30 d for all specimens and their curing times. Two-way ANOVA was calculated for shrinkage and repeated measures ANOVA was calculated for hygroscopic expansion (p<0.05). RESULTS: DeltaV depended on filler load but not on curing time (SU approximately -2.0%, CM approximately -2.6%, CF approximately -2.1%, SO approximately -3.3%, TE approximately -1.7%, FT approximately -1.8%). Hygroscopic expansion depended on water sorption and solubility. Except for SU, all materials showed DeltaV approximately +1% after water storage. CONCLUSION: Polymerization shrinkage depended on the type of resin-based filling material but not on curing time. Shrinkage was not compensated by hygroscopic expansion.

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.

Bacterial leakage in roots filled with different medicaments and sealed with Cavit.

The aim of this study was to evaluate the time required by four different root canal medications coupled with the temporary filling material Cavit (ESPE, Seefeld, Germany) to prevent penetration of bacteria into the root canal. There were 145 roots prepared in a standardized manner. Four groups with 15 samples each were dressed with calcium hydroxide (Ca(OH)(2)), a 5% chlorhexidine gel (CHX), a chloromono-campherphenolic compound (ChKM), and Ledermix (LM), respectively, and sealed with Cavit. Four control groups contained identical medications but the roots were left unsealed. The 25 remaining roots served as additional controls. A standard setup for bacterial leakage studies was chosen with Staphylococcus epidermidis as test strain. Cavit application resulted in a significantly better seal compared with the unsealed groups. In the Cavit-sealed groups, all groups differed significantly from one another except for the CHX and the ChKM groups. The Ca(OH)(2) medicated roots provided the longest protection (median of 36 days), followed by the Ledermix-group (27 days) and the CHX (18 days) or ChKM groups (19 days). It may be concluded that Cavit-sealed and medicated root canals do not provide adequate protection against bacterial leakage for more than 1 month.

The Basal phosphorylation sites of endothelial nitric oxide synthase at serine (Ser)1177, Ser116, and threonine (Thr)495 in rat molar epithelial rests of Malassez.

BACKGROUND: The epithelial rests of Malassez (ERM) are derived from the Hertwig's epithelial root sheath during tooth development. The ERM contain endothelial nitric oxide synthase (eNOS), but the existence of phosphorylation site/s of eNOS in the ERM is unclear. METHODS: Rat molars with periodontium were perfusion- and post-fixed, decalcified, and frozen-sectioned. Free-floating sections were incubated using antisera against total eNOS, eNOS phosphorylated at serine (Ser)1177, Ser116, and threonine (Thr)495. The signal intensities of t-eNOS, p-eNOS at Ser1177 and Ser116 in the ERM were measured by densitometry and statistically analyzed. RESULTS: In the ERM, localization of total eNOS and the phosphorylation sites of eNOS at Ser1177 and Ser116 were detected, while a basal localization of eNOS phosphorylated at Thr495 in the ERM was undetectable. For p-eNOS at Ser116 regional differences in phosphorylation were detected. CONCLUSIONS: The basal production of NO by eNOS in the ERM is modulated by phosphorylation of eNOS at Ser1177 and Ser116 residues, while the basal activity of the eNOS is not influenced by phosphorylation of eNOS at Thr495 residue. This provides evidence that phosphorylation plays a key role for regulation of the catalytic activity of eNOS.