Optoelectronic evaluation of indirect dental veneers interfaces

Dental indirect veneers have become the most functional and cost-effective method for providing high-aesthetic results whenever smile design enhancement is required. Yet, clinical failures have been reported due to the detachment of the veneers from the dental hard tissues, as well as to chipping and microleakage. Many experimental studies have been conducted in order to identify clinical and technical solutions for enhancing the adhesive and biomechanical properties of the veneers, by promoting the same classical, linear marginal contour of these particular indirect restorations. Thus, the aim of this study is to develop a novel design of the veneers deemed to augment the interfacial adhesive forces and, furthermore, to investigate the bonded interfaces by using optical coherence tomography

Investigation of firing temperature variation in ovens for ceramic-fused-to-metal dental prostheses using swept source optical coherence tomography

One of the most common fabrication techniques for dental ceramics is sintering, a process of heating of the ceramic to ensure densification. This occurs by viscous flow when the firing temperature is reached. Acceptable restorations require the alloy and ceramic to be chemically, thermally, mechanically, and aesthetically compatible. Thermal and mechanical compatibility include a fusing temperature of ceramic that does not cause distortion of the metal substructure. Decalibration of ovens used for firing of the ceramic layers for metal ceramic dental prostheses leads to stress and cracks in the veneering material, and ultimately to the failure of the restoration. 25 metal ceramic prostheses were made for this study. They were divided in five groups, each sintered at a different temperature: a group at the temperature prescribed by the producer, two groups at lower and two groups at higher temperatures set in the ceramic oven. An established noninvasive biomedical imaging method, swept source (SS) optical coherence tomography (OCT) was employed, in order to evaluate the modifications induced when using temperatures different from those prescribed for firing the samples. A quantitative assessment of the probes is performed by en-face OCT images, taken at constant depths inside the samples. The differences in granulation, thus in reflectivity allow for extracting rules-of-thumb to evaluate fast, by using only the prostheses currently produced the current calibration of the ceramic oven. OCT imaging can allow quick identification of the oven decalibration, to avoid producing dental prostheses with defects

Optical coherence tomography study regarding the enamel structure before and after debonding

Orthodontic treatments imply the use of different types of adhesives and brackets. However, concerns have been raised regarding the effect of these treatments on the structure of the involved teeth. The debonding process is especially regarded as a concern: due to the use of different pliers tensile and pulling forces the develop on the surface of the tooth. The finishing bur is also a concern. Optical Coherence Tomography (OCT), an emerging technology that performs transverse sections of biological systems has been used in order to obtain a more accurate assessment of enamel quality due to its wide applicability and to its non-invasive properties.OCT, analogous to ultrasound imaging(with the difference that it uses light instead of sound), provides cross-sectional images of the tissue structure on the micron scale, in vivo and in real time. Regarding fixed orthodontic treatments, patients are often subjected in the process to a high risk of enamel decalcification and carious processes. Demineralization usually occurs in the area adjacent to the orthodontic bracket location, where bacterial plaque control is difficult. Therefore, in this study we evaluate using OCT the degree of demineralisation produced in the enamel structure, following the removal of the orthodontic bracket. Also, the amount of adhesive remnants after the removal of the adhesive and the finishing of the dental surface with specific instrumentation is evaluated

Influence of the Printing Angle and Load Direction on Flexure Strength in 3D Printed Materials for Provisional Dental Restorations

The CAD/CAM techniques, especially additive manufacturing such as 3D printing, constitute an ever-growing part of obtaining different dental appliances and restorations. Of these, provisional restorations are of frequent use in daily dental practice and are the object of this study. Masticatory and parafunctional forces determine flexure on these prostheses. This study investigates the influence of the printing angle and loading direction of the applied force on the flexure strength of two commercially available printable resins—Detax Freeprint Temp and Nextdent MFH Vertex dental. Ten rectangular beam specimens printed at the angle of 0, 45 and 90 degrees were fabricated of each of these materials, with an addition of 10 at 0 degrees for the investigation of the load direction. Three-point bending tests were performed in a universal testing machine. Flexure strength, strain at break and Young’s modulus were determined and a statistical analysis was performed on the obtained data. According to the statistical analysis, the flexural strength has a significance dependence with respect to degrees of orientation, for both investigated materials

SELF-ASSESSMENT OF DENTAL PREPARATIONS IN THE PHANTOM HEAD WITH PREPCHECK – A QUESTIONNAIRE-BASED EVALUATION

Background: As part of pre-clinical teaching at Danube Private University (DPU), CAD/CAM systems (CEREC) are introduced in the third semester. In addition, students learn how to use software for self-assessment of their dental preparations in the phantom head (prepCheck). Objectives: The students’ perspective and feedback is important for the success of teaching modules, which is why their opinion of the prepCheck analysis app was evaluated by means of an anonymous questionnaire. Methods: A survey study was conducted with an anonymized questionnaire. This was followed by a descriptive statistical analysis of the ratings of the statements. Results: The use of prepCheck was predominantly evaluated positively and the learning content was positively received. The training of assessment skills as well as the promotion of study motivation, the acquisition of a better understanding and the optimized self-assessment through prepCheck could also be affirmed. However, prepCheck cannot replace teacher feedback. Conclusion: Besides traditional teaching and performance assessment by the teacher, prepCheck is positively perceived as an additional teaching and self-assessment method

Non-invasive imagistic investigations of repaired IPS Empress e.max all ceramic crowns

The present study is proposing to investigate through non-invasive techniques, the quality of repaired of all-ceramic crowns with ceramic material. 20 all-ceramic crowns made with IPS e.max Empress System. The ceramic component was removed with a grinding instrument from the buccal-incisal of each crown. The ceramic veneer was removed in order to simulate the fracture of the ceramic supra-structure. Defect's size was approximately 3Ã?3mm for all the specimens. In some cases the incisal margin was also removed. All the crowns were repaired with ceramic material VM7 (Vita) after the manufacturer's instructions. The repaired area was investigated through imagistic and also non-invasive techniques. The involved investigation systems are analyzing macroscopic and microscopic the repaired area. Optical Coherence Tomography Time Domain and X ray. Optical Coherence Tomography is an optical microscope which can scan the surface and deep layers of the investigated interface. X ray is useful in detecting macroscopic defects and gaps into the material mass. The quality of the repaired defects may be evaluated and some clinical indications can be made

ASSESMENT OF CROWN PREPARATIONS WITH “prepCheck” – A PILOT STUDY

Objectives The aim of the study was to find out to what extent subjective influences on the evaluation of crown preparations can be reduced by using “prepCheck” analysis software. Material and methods In the 3rd semester as part of the Curriculum Cerec, model tooth 36 was to be minimally invasively prepared in the phantom head to accommodate a fully anatomical, monolithically milled crown made of IPS e.max CAD (Ivoclar Vivadent AG, Schaan, Principality of Lichtenstein) material. In total 18 preparations were evaluated three times (two individual evaluations and one group evaluation) at intervals of three weeks. The model teeth were evaluated in two ways: (1) conventionally, visually and (2) using “prepCheck” analysis software. Cohen’s Kappa coefficient and Fleiss’ Kappa coefficient were used to compare the agreement between the assessments. Results Without the use of the analysis software, the overall results differed significantly. In the first assessment there was a strong agreement ( = 0.7) and in the second assessment after three weeks an adequate agreement ( = 0.4). While in all assessments with “prepCheck” a (nearly) perfect agreement was achieved ( = 1). Conclusion Using the “prepCheck” analysis software, compared to visual assessment, increases the failure rate while reducing intra- and inter-individual variability. PrepCheck is therefore a reliable instrument for evaluating preparations of model teeth, as it eliminates the human factor. At the same time, the software evaluates the preparations much more critically, which leads to higher failure rates. This can lead to demoralisation of the students. The sole use of the software for exam evaluation should therefore be critically examined; prepCheck is excellently suited as a self-assessment tool during practice times in the phantom

The dynamic of acetone effects to the superficial layer of acrylic teeth in Time Domain C Scan (En Face) OCT non invasive investigations

The investigation of the dynamics of acetone effects induced to the superficial layer of acrylic teeth with time domain C Scan OCT is the main reason of this study. Acetone is one of the organic solvents used in order to improve the adhesion of acrylic teeth to denture base resin. The ridge lap area of 20 acrylic second upper molars was milled to flat. Afterwards the molars with the milled ridge lap area were cut in two halves. The artificial teeth were randomly assigned in 2 groups.: Group 1. (control) (without treatment), Group 2. Acetone treatment. The both sample groups were submitted to OCT C Scan (En Face) investigation for 200 seconds. The dynamical changes, induced to the superficial layer of acrylic teeth by acetone, among which the superficial layer hardening, were captured with C Scan OCT, proving the fact that time domain C scan OCT could be used in order to investigate the dynamics of the effects of this organic solvent to the polymeric acrylic teeth substrate

Qualitative study of repaired metal ceramic crowns

The purpose of this study is to investigate the reparation of metal ceramic crowns with ceramic mass. 30 metal ceramic crowns which restore the upper first central incisor (2.1) were divided in three groups. Each group was repaired with a different ceramic material. Group 1- In Line (Ivoclar Vivadent) ceramic, the second group was repaired with D. Sign (Ivoclar Vivadent) and for the last group was used VMK. Master (Vita). All the repaired crowns were investigated through imagistic non-invasive methods. The metallic infrastructure of the samples was made from Ni-Cr alloy and the porcelain mass was Kiss (D. Sign). Defects were made on the buccal surface of each crown. The ceramic mass and the opaque were removed and the metallic infrastructure was exposed. Size defects has 3Ã?3mm and it is situated on incise and 1/3 medium buccal surface. The defect was made with a green grinding instrument under air-water cooling. All the samples were conditioned and repaired with ceramic mass. The reparations were investigated with two noninvasive imagistic methods Rx and Optical Coherence Tomography Time Domain in order to detect de reparation's defects. The investigation methods may spot the presence or absence defects localized at the interface between the two materials and those localized in the ceramic mass