Making use of three-dimensional models of teeth, manufactured by stereolithographic technology, in practical teaching of endodontics.

INTRODUCTION: Making use of 3D printed teeth models in teaching students offers an innovative approach. The mistakes made by the students at the access cavity stage were assessed with the aid of 3D models, and their overall, hands-on learning progress was evaluated. MATERIAL AND METHODS: Ninety 3D models of teeth were constructed using stereolithographic technology and then randomly divided into 9 groups. One dentistry student was randomly assigned to each group and then performed primary access cavity in 10 identical 3D models. Then the teeth were evaluated in the order of their preparation, relative to the model tooth. RESULTS: The material of 14 (15.5%) out of 90 teeth models sustained significant damage during the preparation. As regards the remaining 76 (84.5%) 3D models, the students committed the greatest number of mistakes on the incisors, and fewer on the molars and the least in the premolars. The difference in the number of errors between particular groups of teeth was statistically significant (P = .0001). The number of errors committed in subsequent repetitions amongst all students was significantly different for the incisors (P = .00215) and premolars (P = .00383), whereas insignificant in the case of molars (P = .77116). CONCLUSIONS: Thanks to perfect representation of teeth anatomy; making use of 3D models in the teaching of endodontics may well be recommended as holding substantial potential in improving overall quality of training at the pre-clinical stage, with a view to appreciably reducing overall risk of encountering complications during the actual clinical work.

The influence of a selected desensitizer on marginal microleakage of a class V composite restoration subjected to thermocycles: an in vitro study.

INTRODUCTION: Dentin hypersensitivity is a painful clinical condition. The frequency of its occurrence varies from 8 to 57%, depending on tested group and different methods of investigations. Recommended desensitizing agents have different mechanism of action and effectiveness. We are still looking for solutions that will improve their effectiveness and simultaneously allow for wider use of e.g. as a base material, counteracting postoperative hypersensitivity, reducing marginal microleakage. The aim of the study was to assess the effect of a selected desensitizing agent occluding dentin tubules with calcium hydroxyapatite on marginal microleakage formation of a class V composite restorations subjected to thermocycles. MATERIALS AND METHODS: In study it was used 40 molars and premolars, which were alternately assigned into two groups. In both groups standardized cavities were prepared. In the study group (study group - SG) before application of bonding agent Teethmate Desensitizer (f. Kuraray, Noritake Dental Inc., Okayama, Japan) was used. In the control group (control group - CG) OptiBond All-in-one (f. Kerr, Bioggio, Switzerland) bonding agent was used and cavities were filled using composite material Gradia Direct (f. GC Europe N.V., Leuven, Belgium). After storage in saline, teeth were subjected to 600 thermocycles, passive dye penetration test was done, teeth were cut in the area of filling, according to its long axis. Under light microscope magnification value of microleakage was measured and marginal microleakage rate (M) was counted. The results of the tests were statistically analyzed using the package STATISTICA 12.0 (StatSoft, USA). RESULTS: The average value of M for the SG group was 0.46 (min 0.05, max 0.76, SD 0.226) and for CG was 0.22 (min 0, max 0.74, SD 0.235). The differences between M values were statistically significant (p = 0.0094). CONCLUSION: A reduction in the number of retention sites for the bonding system, facilitates the formation of microleakage in the experimental conditions and reduces the degree of adhesion of the composite material to the hard tissues of the tooth.