Susceptibility artifacts induced by crowns of different materials with prepared teeth and titanium implants in magnetic resonance imaging

This study aimed to investigate the artifacts induced by crowns composed of different materials with prepared teeth and titanium implants. Resin, metal-ceramic, ceramic and zirconia crowns were fabricated and placed onto the prepared teeth on a human cadaver head or titanium implants with prosthesis abutments on a dry human mandible. The samples were scanned on a 1.5 T MRI apparatus, and artifact areas were defined as the signal intensity and signal loss adjacent to the prosthesis and measured by a threshold tool with ImageJ2x. Data were analyzed using SPSS 22.0. Resin, ceramic, zirconia, and precious metal-ceramic crowns barely produced artifacts on the cadaver skull (p > 0.999). By contrast, pure Ti and nonprecious metal-ceramic crowns created significant artifacts (p < 0.001). The average artifacts reduction of double Au-Pt and Ag-Pd metal-ceramic crowns combined with titanium implants and abutments was 79.49 mm2 (p < 0.001) and 74.17 mm2 (p < 0.001) respectively, while artifact areas were increased in double Co-Cr and Ni–Cr metal-ceramic crowns by 150.10 mm2 (p < 0.001) and 175.50 mm2 (p < 0.001) respectively. Zirconia, ceramic and precious metal-ceramic crowns induce less MRI artifacts after tooth preparation while precious metal-ceramic crowns alleviate artifacts in combination with titanium implants.

Aesthetic and functional rehabilitation in a patient with anterior skeletal open bite using lithium dissilicate glass-reinforced ceramic: a case report

The aim of this clinical report is to present the replacement of unsatisfactory metal-ceramic crowns of elements 12, 11, 21 and 22, by lithium disilicate glass-reinforced ceramic crowns in a patient with skeletal anterior open bite. A patient sought care at the Dental Hospital at the School of Dentistry of UFU, complaining of odor between the metal-ceramic crowns of the antero-superior teeth. After clinical and radiographic examination, invasion of the biological space was noticed, surgery was indicated in order to restore the biological space. After healing, the pre-existing cast metal posts were masked using an opaque composite resin and the teeth were reprepared for full all-ceramic crowns. Impressions were taken in two steps, using PVS associated to retraction cords. The ceramic copings were obtained in lithium disilicate ceramic, and the veneering was performed by stratification. After testing the ceramics crowns in relation to, fit, function and aesthetic results, cementation was completed using modified absolute isolation, followed by prophylaxis of preparations with pumice and saline, surface treatment of the ceramic restorations and luting using self-adhesive resin cement. Finally, an occlusal splint was produced to control the effects of bruxism and orofacial pain symptoms. The anterior open skeletal bite was a challenging factor for the rehabilitation of this patient; however, one must consider the entire process that the patient would undergo if choosing for orthognathic surgery, and the patient should be aware of the case limitations. In addition, the use of lithium disilicate glass-reinforced ceramics proved the versatility of this material for anterior aesthetic restorations.

Peg-Shaped Lateral Incisors Treated with Ceramic Three-Quarter Crown

In recent years, patients’ expectations are becoming higher in terms of esthetic dentistry. Having the ideal smile is becoming a purpose as the appearance of stars and famous persons have been undoubtedly improved through smile correction. Peg-shaped lateral incisors are a common dental form aberration which could distort the smile and may hamper patient psychology because of the smaller shape and size in disharmony with other teeth. Three-quarter ceramic veneers are a mini-invasive approach which could solve the esthetic problem of peg-shaped teeth and ensure patient’s satisfaction. The present paper was about a clinical case with peg-shaped lateral incisors treated with three-quarter ceramic crowns. It would also highlight the preparation particularities.

Polymer-Based Bioactive Luting Agents for Cementation of All-Ceramic Crowns: An SEM, EDX, Microleakage, Fracture Strength, and Color Stability Study

The aim of the study was to compare microleakage and fracture loads of all ceramic crowns luted with conventional polymer resins and polymeric bioactive cements and to assess the color stability of polymeric bioactive cements. Seventy-five extracted premolar teeth were tested for fracture loads and microleakage in all-ceramic crowns cemented with two types of polymeric bioactive cements and resin cements. In addition, the degree of color change for each cement with coffee was assessed. Thirty maxillary premolar teeth for fracture loads and thirty mandibular premolar teeth for microleakage were prepared; standardized teeth preparations were performed by a single experienced operator. All prepared specimens were randomly distributed to three groups (n = 20) based on the type of cement, Group 1: resin cement (Multilink N); Group 2: polymeric bioactive cement (ACTIVA); Group 3: polymeric bioactive cement (Ceramir). The cementation procedures for all cements (Multilink, ACTIVA, and Ceramir) were performed according to the manufacturers’ instructions. All specimens were aged using thermocycling for 30,000 cycles (5–55 °C, dwell time 30 s). These specimens were tested using the universal testing machine for fracture strength and with a micro-CT for microleakage. For the color stability evaluation, the cement specimens were immersed in coffee and evaluated with a spectrometer. Results: The highest and lowest means for fracture loads were observed in resin cements (49.5 ± 8.85) and Ceramir (39.8 ± 9.16), respectively. Ceramir (2.563 ± 0.71) showed the highest microleakage compared to resin (0.70 ± 0.75) and ACTIVA (0.61 ± 0.56). ACTIVA cements showed comparable fracture loads, microleakage, and stain resistance compared to resin cements.

Clinical Evaluation of Reduced-Thickness Monolithic Lithium-Disilicate Crowns: One-Year Follow-Up Results

Purpose: The purpose of this in vivo study was to investigate whether the less invasive approach (reduced thickness of the restoration) will result in a comparable risk of failure and similar aesthetic results, compared to conventional layered full porcelain crowns, and can, therefore, be used as a good alternative. Material and Methods: The tested ceramic was lithium-disilicate ceramic (IPS e.max). Forty-four patients with endodontically treated premolars or molars were randomized into two groups and provided with single crowns. One group received conventional all-ceramic crowns made from a lithium-disilicate core and hand-veneered aesthetic ceramic, while another group received full-contoured lithium-disilicate ceramic crowns with reduced wall thickness than manufactures recommendations. The teeth for conventional crowns were prepared with 1 mm rounded shoulder and 2 mm occlusal reduction, while teeth for monolithic crowns were prepared with 0.6 mm wide rounded shoulder and 1 mm occlusal reduction. All crowns were prepared by the same clinician and manufactured in the same laboratory by the same technician. The survival and aesthetics of the crowns were assessed by the independent clinician. Apart from this, patients’ aesthetic satisfaction was evaluated. The assessment was double blind as both the examiner and the patients did not know which type of crown was provided. The observation period was 36 months. Survival of the crowns was assessed using the modified United States Public Health Service (USPHS) criteria and aesthetics and participants’ aesthetic satisfaction with the crowns was evaluated using a visual analogue scale. Results: The one-year survival rate for layered crowns was 100% and for monolithic crowns 95.5%. The median patients’ aesthetic satisfaction with both crowns was 100%. Conclusions: The results indicate similar one-year survival rate of reduced-thickness monolithic lithium-disilicate crowns and conventional veneered crowns. Differences with patients’ satisfaction with the aesthetics of both crowns were not statistically significant and it can be said that the patients’ aesthetic satisfaction was the same for both crowns.

The Influence of Three Different Digital Cement Spacers on the Marginal Gap Adaptation of Zirconia-Reinforced Lithium Silicate Crowns Fabricated by CAD-CAM System

Background: This study compared the influence of three different radial spacers (60,90,120 microns) on the marginal gap adaptation by using computer-aided manufacturing (CAD-CAM) for producing monolithic zirconia reinforced lithium silicate (ZLS) ceramic crowns. Methods: A total of 45 abutment acrylic teeth were divided into three groups of different radial spacers (60, 90, and 120 microns). In each group 15 teeth were scanned by Omnicam intra oral scanner and ZLS crowns were ground. For each unit the marginal gap was evaluated at four regions of interest by scanning electronic microscope (SEM). To compare the marginal gap between the three groups a one-way ANOVA with post-hoc Bonferroni test was preformed (α = 0.05). Results: The marginal gap for a 60 microns (162.99 ± 16.25 µm) radial spacer was found significantly higher than 90 (41.85 ± 3.57 µm) and 120 (41.85 ± 5.3 µm) microns radial spacers (p < 0.05). Between 90- and 120-micron radial spacers no difference was obtained. (p < 0.05). Conclusions: A radial spacer of 60 microns showed a significantly higher marginal gap compared to 90 and 120 microns and was not clinically accepted (>120 microns). For both 90 and 120 microns the marginal gap was clinically accepted (<120 microns) with no difference between the groups. The radial spacer which should be optimum for CELTRA® DUO crowns is 90 microns.

Digital restoration of maxillary central incisors after trauma using an intraoral scanner and a CAD/CAM system in an 11-year-old

Background: Most dental trauma in children and adolescents involve anterior tooth fractures. Advancements in ceramics technology and in computer-aided design/computer-aided manufacturing (CAD/CAM) systems, have led to the technological abilities to produce single all-ceramic crowns with high biocompatibility, esthetics, and optimal mechanical properties. However, there is no information regarding the use of this technique in children. Case report:Treatment of extensive crown fractures on an 11 years old patient using a chairside CAD/CAM technology. The teeth were scanned and the restorations were fabricated using the manufacturing unit of the CAD/CAM system and glazed to the appropriate tooth color. At a follow up visits the restorations kept their strength and esthetic appearance (one year follow up). Conclusion: The digital restoration treatment is especially suitable for treating children with dental trauma. It has the advantage of better esthetic, functional and durable results compering to conventional restorations, and it often requires only a single session.