The clinical relevance and correlation between the initial straight length to the first curvature in human second maxillary premolars.

The aim of this study was to evaluate the straight lengths of the root canal of human second maxillary premolars using standardized radiological techniques in vitro. The distances were examined starting from the cemento-enamel junction (CEJ) to the appearance of a curvature. In particular recommendations which may facilitate decision making with regard to the length of post systems after successful endodontic treatment should be available. Extracted human second maxillary premolars (n = 210) were used; teeth with root caries, artificial crowns, extensive fillings or with previous endodontic treatment were excluded from this investigation. The teeth were fixed in a specially developed device with standardized and reproducible distances and digital radiographs using the parallel technique were made. A descriptive statistical analysis and the calculation of the cumulative frequencies were made. The values for the distance starting from the CEJ to a first curvature were as follows: a) For right second premolars: median value=10.3 mm (min.: 5 mm; max.: 15.8 mm) and mean value= 10.4 SD+/- 2.6 mm; b) left second premolars: median value =10.2 mm (min.: 5 mm; max.: 17 mm) and mean value =10.3 mm SD +/-2.2 mm. Based on our data, high number of second maxillary premolars showed a curvature (30.4%) 9 mm apically from the CEJ. These findings should be taken into consideration for endodontic treatments and post insertions.

Survival rate of endodontically treated teeth in relation to conservative vs post insertion techniques -- a retrospective study.

AIMS AND METHODS: The purpose of this retrospective, non-randomised cohort study was to evaluate the success rate of 775 endodontically treated teeth depending on the restoration type. A total of 508 patients with 775 endodontically treated teeth were examined during at least 12 months. The radiographic controls, time span between root canal filling and definitive restoration, restoration material type, inserted post system type and the occurrence of possible endodontically as well as restorative post-operative complications were recorded. RESULTS: 18.3% of the 775 investigated teeth were incisors and canines, 33.5% were premolars and 48.2% molars. Pre-fabricated and casted metal post systems were used only in 15.6% of the endodontically treated teeth (18.4% incisors and canines, 44.8% premolars, 36.8% molars). 6.6% of the teeth had endodontically related symptoms or severe complications, whereas in 13.2% of the teeth restored with metal posts showed complications, such as root or crown fractures. The Cox-Regression analysis showed that teeth restored with a post system had a statistically significant higher failure rate (p = 0.044) than those which had been restored without posts. CONCLUSIONS: The results showed a high success rate for endodontically treated teeth when the final restoration was placed within a short period of time (two weeks). A higher tooth loss was observed when metal post systems were employed suggesting that precaution is recommended when these types of posts are inserted.

Effect of calcium hydroxide and chlorhexidine based gutta-percha points on gingival fibroblasts and epithelial tumor cells.

AIMS AND METHODS: The aim of the present study was to demonstrate the possible effect of different endodontic calcium hydroxide and chlorhexidine-based gutta-percha points, on two different human cell culture systems. Two different calcium hydroxide (Roeko, Langenau, Germany) and one chlorhexidine (Activ Point/Roeko, Langenau, Germany) gutta-percha points were tested with gingival fibroblasts and epithelial tumor cells over a period of six days (n = 12). Conventional gutta-percha points (VDW, Munich, Germany) and cells that were not exposed to any substances served as controls (n = 12). Study parameters included cell vitality, cell count, protein synthesis and cell proliferation. RESULTS: All tested materials induced cell growth specific alterations. Chlorhexidine-based gutta-percha points showed a significant lower protein synthesis with both, gingival fibroblasts (0.013 +/- 0.009 mg/ml) and epithelial tumor cells (0.07 +/- 0.039 mg/ml), when compared with the controls (p > 0.05). Protein synthesis increase of the epithelial tumor cells (0.581 +/- 0.013 mg/ml, control) was observed with the conventional gutta-percha points (0.688 +/- 0.078 mg/ml) and with both gutta-percha points containing different calcium hydroxide-based formulations (0.776 +/- 0.115 and 0.7 +/- 0.047 mg/ ml). CONCLUSIONS: Under the conditions of this study, chlorhexidine containing gutta-percha points showed the highest effect on cell growth inhibition. No significant differences were observed between the tested material and the two different cell culture types.

Effect of apical root-end filling materials on gingival fibroblasts.

AIM: To determine the influence of root-end filling materials on specific cellular responses of gingival fibroblasts (GF). METHODOLOGY: The reactions of cells in contact with mineral trioxide aggregate (MTA), amalgam and a chemically inert titanium alloy were determined based on the assessment of prostaglandin (PGE2) release with and without arachidonic acid stimulation, protein and lactate synthesis, and cell proliferation. Cells cultured without test materials served as controls (100%). RESULTS: The fibroblasts showed a highly significant decrease in protein synthesis when in contact with amalgam (61.8 +/- 13.6%); MTA (91.2 +/- 5.9%) and titanium (92.4 +/- 4.7%) had little effect on this parameter. The rate of cell proliferation in contact with MTA (98.0 +/- 1.6%) and titanium (97.9 +/- 7.4%) was only slightly influenced and showed similar values to that of the controls after 96 h of incubation. On the contrary, a significant and continuous reduction in the rate of cell proliferation was observed for cells in contact with amalgam (61.0 +/- 2.5%) after 96 h. No significant increases in lactate synthesis values were registered for any of the materials (MTA 101.8 +/- 1.7%, titanium 94.8 +/- 8.6% and amalgam 105.8 +/- 10.3%). There was a significant decrease in PGE2 synthesis potential when cells were in contact with amalgam (85.2 +/- 3.5%). In comparison to the controls, titanium and MTA resulted in an elevated level of cellular PGE2 synthesis (titanium: 131.6 +/- 19.1%; MTA: 147.3 +/- 18.9%). The cell cultures stimulated with arachidonic acid (10-5 m) showed no significant differences with any material (MTA: 88.8 +/- 17.6%, titanium: 97.6 +/- 14.4%, amalgam: 85.5 +/- 16.8%). CONCLUSIONS: MTA demonstrated cellular responses similar to those of titanium. Amalgam showed an irritation rate higher than that of MTA and titanium.

Dimensional variability of nonstandardized greater taper finger spreaders with matching gutta-percha points.

AIM: The purpose of this research was to determine the compatibility and dimensional variability between nonstandardized gutta-percha points and matching finger spreaders. METHODOLOGY: The diameters of nonstandardized gutta-percha points (n = 15) and matching finger spreaders (n = 15) from different manufacturers (Kerr, Dentsply Maillefer, Vereignigte Dentalwerke and Roeko) were determined and statistically analysed using a profile projector under a magnification of 50 x (+/- 0.002 mm). RESULTS: The dimensions of the finger spreaders and gutta-percha cones were inconsistent. Of the 29 groups of nonstandardized gutta-percha cones evaluated, 22 had standard deviations larger than 0.020 at D1. The standard deviations at D11 were greater than at D1, with the exception of those manufactured by Roeko. Overall, nonstandardized gutta-percha cones made by VDW had the greatest dimensional consistency within each size group; the largest variations were seen in the Dentsply Maillefer gutta-percha points. The 13 sizes of nonstandardized finger spreaders were more consistent. CONCLUSIONS: The results of this study show that corresponding sizes of nonstandardized finger spreaders and gutta-percha cones have statistically significant differences. There were large dimensional variations within sizes and discrepancies between the nominal size and actual size. Thus, these discrepancies may cause problems during root canal filling.

Canal transportation caused by a new instrumentation technique and three standard techniques.

The ability of three different enlarging techniques (balanced force concept, step-back, and recapitulation) and a prototype system to maintain the original canal path during root canal preparation were compared, in vitro, with a theoretical ideally prepared root canal. Measurements were made at the concave and convex sides of the canal at four different levels (1, 4, 5, and 7 mm from apical, respectively). Simulated root canals embedded in clear casting resin and an enlarging computer-supported device were used for this study. The results showed that none of the enlarging techniques used in this study was able to prepare a canal ideally. The prototype system, at level 1, showed an ideal amount of material removed from the concave side and less, in comparison with the other techniques, from the convex side of the canals. The same tendencies persisted at all levels, with the exception of the level 4 concave side.

Microleakage of gold casting repairs with different materials as quantified by a helium gas system.

Inadequate adaptation of a filling material to a gold crown can promote the passage of bacteria; thus, recontamination of sound dentin and/or the pulp canal space is feasible. The aim of this study was to determine the marginal microleakage between two different amalgams (Tytin and Valiant PHD-XT), three different composites (Tetric, Charisma, and Polofil Molar), and one glass-ionomer cement (Ketac Silver) and gold cast crowns using a helium gas microleakage method. In order to standardize the research parameters, gold washers with standardized dimensions were used as study models together with a helium leakage testing device. Standardized cavities were filled according to the manufacturers' recommendations with the different materials. The amount of helium passing the marginal interface between the fillings and cavities was measured with a mass spectrometer 48 hours after the fillings were placed and 100, 1000, and 2000 thermocycles (5 degrees C-55 degrees C). The results showed that amalgam allowed the least microleakage. Ketac Silver showed the greatest microleakage. Statistically significant differences were found between the composites and both amalgams and Ketac Silver between the 48-hour and 100-thermocycling groups. Yet, Ketac Silver showed a significant ascending tendency when compared to the composites and amalgams after 100, 1000, and 2000 thermocycles.

[The reliability of apical x-ray pictures in the diagnosis of mandibular bone lesions. A review of the literature and in-vitro study]. / Zuverlässigkeit apikaler Röntgenaufnahmen bei der Diagnostik von Unterkieferknochenläsionen. Literaturübersicht und In-vitro-Untersuchung.

Using 6 macerated human anatomical preparations of mandibular jaw regions with either front teeth or premolars and molars, the radiological detectability of artificial periapical bone lesions was evaluated in relation to the size of the lesions and to the angle of x-ray projection. The artificial lesions were enlarged stepwise until distinct radiological visibility was attained. For each step of enlargement, x-ray pictures were taken with orthoradial as well as with at 25 degrees mesially and distally excentered projections. All x-ray pictures were evaluated by 6 dentists. The following results were obtained: The size of a periapical bone lesion, at which it is becoming radiologically detectable, varies between the different regions of the lower jaw. Isolated spongiosa lesions being larger than 3 mm in diameter are most often detectable at mandibular front teeth and premolars. Isolated spongiosa lesions at mandibular molars are generally non-detectable. Atypical lesions, e.g. discontinuities of bony structures are particularly difficult to detect radiologically. There were no statistically significant differences in lesion detectability between x-rays of different angle projections.

The influence of different engine-driven, sound ultrasound systems and the Canal Master on root canal preparation: an in vitro study.

Different methods and automated devices have been developed to accomplish the enlarging and debriding of root canals. The occurrence of undesired effects on the root canal walls was compared in vitro between a theoretically ideally shaped canal and the Canal Leader, Canal Finder, 3000 Endo Sonic Air, Cavi Endo 25, Enac System, Piezon Master 400 and the Canal Master. Clear casting resin models were used for this purpose. A photographic double exposure was used to superimpose the images of the original canals on the enlarged canals, thus enabling measurement of the material removed. Measurements were made at six different points. Significance was defined at the 5% level (P = 0.05). All instruments and/or devices, with the exception of the Cavi Endo 25, enlarged the convex side of the canals significantly greater at level 1 in comparison to the ideal. On the concave side, significantly smaller differences were found between the ideal and the results of all the enlarging devices, with the exception of the Canal Master. On the convex side at level 2, the Canal Leader, Canal Finder, Cavi Endo, Enac System and Endo Sonic Air showed no statistical differences between ideal and effective material removal. The Piezon Master showed significantly lower material removal in comparison to the ideal. The Canal Master demonstrated statistically higher differences when compared with the ideal.(ABSTRACT TRUNCATED AT 250 WORDS)