Biomedical subjects

C Dobó-Nagy

Publications and source records attributed to C Dobó-Nagy.

4 recordsLinked to original sources

PubMed2006

The influence of root canal shape on the sealing ability of two root canal sealers.

AIM: To evaluate the influence of root canal form on the sealing ability of two root canal sealers. METHODOLOGY: Twenty radiographically confirmed straight and 20 curved root canals were prepared with a stepback hand filing technique. Root canal aberrations created during preparation were determined by the use of double exposure radiographic technique. The prepared canals were filled with lateral condensation of gutta-percha and one or other of two root canal sealers (Pulp Canal Sealer and Sealapex). Leakage along the apical 10 mm of roots was measured with a fluid transport model at 1, 3, 6, 9 and 12-month intervals. RESULTS: There were no statistically significant differences between straight and curved root canals (P > 0.05) for prevalence of root canal transportation. The prevalence of apical transportation was 80% in the straight and 85% in the curved root canals. A complete seal was more frequently observed in straight canals compared with curved canals. Utilizing the pi* index, analysis showed the filling with Sealapex allowed more leakage than Pulp Canal Sealer at 1 year. CONCLUSION: Under the conditions of the study, root canal form influenced short-term sealing ability. In the long-term the seal was affected by the sealer rather than root canal form.

Analysis of Variance↗

PubMed2003

Measurement of periapical pressure created by occlusal loading.

AIM: To develop an in vitro model in which the pressure in the periapical tissues can be measured during loading. METHODOLOGY: Extracted human maxillary central incisors were embedded in resin blocks that had physical characteristics similar to those of bone and periodontal ligament. Each tooth was loaded with 20, 40, 50, 60, 75, 85, 100, 200, 300 and 450 N vertical forces from the incisal edge of the crown on three consecutive occasions. A minute resistor embedded in the periapical space was used to detect apical pressure changes during occlusal loading. The ratio of apical pressure changes (DeltaP) to the loading force changes (DeltaF) was calculated. RESULTS: The periapical pressure detected was in direct proportion to the loading force. The mean value of DeltaP/DeltaF was 5.994 kPa N-1 (SD = 2.04). CONCLUSIONS: Direct proportionality was found between the coronal loading and the apical hydrostatic pressure. The DeltaP/DeltaF ratio determined in this study makes it easier to estimate the apical hydrostatic pressure values during occlusal loading of single-rooted teeth. In this study, the apical pressure generated under occlusal loading was the same magnitude as that estimated with the finite element method.

Alveolar Process↗

PubMed2002

A comparison of the shaping characteristics of two nickel-titanium endodontic hand instruments.

AIM: The purpose of this study was to compare the shaping characteristics of Ni-Ti K-files and Ni-Ti S-files manipulated by hand. METHODOLOGY: A total of 60 extracted human roots were embedded in resin blocks. The embedded roots were divided into three groups: (i) roots with straight; (ii) apically curved; and (iii) continuously curved canals. Each of the three groups was randomly divided into two subgroups; one subgroup in each group was prepared with Ni-Ti K-files and the other with Ni-Ti S-files. The files were used with a step-back technique and enlarged so that the master apical file was size 30, and the canals were stepped back to size 40. The performance of the files was assessed by the superimposition of projected radiographs taken in bucco-lingual and mesio-distal directions before and after the preparation. The results were analysed statistically using analysis of covariance and Duncan's multiple range test. RESULTS: Although canal preparation using Ni-Ti K-files was quicker, there were no statistically significant differences between file types. The Ni-Ti S-file removed significantly more material at the most coronal level (P < 0.05). There were minor differences between instruments at the apical level. Only in the proximal view of apically curved canals prepared with Ni-Ti S-files was significantly more dentine removed from the outer aspect of the curvature (P < 0.05). At the middle level (wide danger zone) the Ni-Ti S-files removed more dentine from the inner aspect of the curvature in those roots with apically curved canals. CONCLUSIONS: Under the conditions of this study, preparation with Ni-Ti K-files produced more appropriate shapes in roots with apically curved canals than Ni-Ti S-files.

Analysis of Variance↗

PubMed2000

A computerized method for mathematical description of three-dimensional root canal axis.

Knowledge of the three-dimensional (3D) morphology of root canals is important for successful endodontic treatment. The objective of the present study was to determine the 3D root canal axis mathematically. Two views (mesiodistal and buccolingual) of digitized images were taken from extracted natural human teeth. Geometric reconstruction to standardize projection geometry was conducted on images. Because 90-degree turn-around image pairs are Monge images of a given root canal, these Monge images were positioned using photogrammetric methods. Each well-ordered axis pair of a given root canal was put into a common coordinate system resulting in 3D polynomial function of the actual root canal. On the basis of the results gained using 10 samples evaluated with the Friedman statistical test, this description seems to be reproducible. The 3D representation of the root canal may help the clinicians in choosing the optimal instruments and shaping techniques. The root canal axis that is described by the 3D function forms a basis for determination of curvature values and torsion values in each of the axis points. Evaluating these values may also yield a new type of classification.

Algorithms↗