Comparison of the flexural strength of printed and milled denture base materials.

BACKGROUND: To evaluate the flexural strength of digitally milled and printed denture base materials. METHODS: The materials tested were Lucitone 199 denture base disc (Dentsply Sirona), AvaDent denture base puck (AvaDent), KeyMill denture base disc (Keystone), Lucitone digital print denture base resin (Dentsply Sirona), Formlab denture base resin (Formlabs), and Dentca base resin II (Dentca). Sixty bar-shaped specimens of each material were prepared for flexural strength testing and were divided into five groups: control, thermocycled, fatigue cycled, and repair using two different materials. The flexural strength and modulus were tested using a 3-point bend test performed on an Instron Universal Testing Machine with a 1kN load cell. The specimens were centered under a loading apparatus with a perpendicular alignment. The loading rate was a crosshead speed of 0.5 mm/min. Each specimen was loaded with a force until failure occurred. A one-way ANOVA test was used to analyze the data, followed by Tukey's HSD test (α = 0.05). RESULTS: The milled materials exhibited higher flexural strength than the printed materials. Thermocycling and fatigue reduce the flexural strengths of printed and milled materials. The repaired groups exhibited flexural strengths of 32.80% and 30.67% of the original flexural strengths of printed and milled materials, respectively. Nevertheless, the type of repair material affected the flexural strength of the printed materials; the composite resin exhibited higher flexural strength values than the acrylic resin. CONCLUSIONS: The milled denture base materials showed higher flexural strength than the printed ones.

Fracture Strength of Endocrowns Fabricated From Three Different Computer-Aided Design/Computer-Aided Manufacturing Ceramic Materials: An In-Vitro Study.

INTRODUCTION: Endocrown restorations have increased in popularity in recent years due to the advancement of both adhesive and restorative materials. The clinical success of endocrowns depends on several factors, including preparation design, material selection, fracture resistance, and marginal adaptation. The aim of this in vitro study was to compare the fracture strength of endocrown restorations fabricated from three different computer-aided design (CAD)/computer-aided manufacturing (CAM) materials. METHODS: Thirty extracted mandibular first molars were selected. The teeth underwent conventional root canal treatment before being prepared for endocrown restoration. The teeth were allocated to three groups (n=10), corresponding to each of the three ceramic materials used to fabricate the endocrowns they would receive. The ceramic materials used were zirconia-reinforced lithium silicate glass-ceramic (VITA Suprinity, VITA Zahnfabrik, Bad Säckingen, Germany), polymer-infiltrated hybrid ceramic (VITA Enamic, VITA Zahnfabrik, Bad Säckingen, Germany), and lithium disilicate glass-ceramic (IPS e.max CAD, Ivoclar Vivadent, Schaan, Liechtenstein). The specimens were scanned, and the digital impressions were transferred into design software to construct the endocrowns. The endocrowns were then milled and cemented. A universal testing machine (5969L3504, Instron, USA) was used for the fracture strength test at a crosshead speed of 1 mm/min until catastrophic failure occurred. Statistical analysis was performed using IBM Corp. Released 2015. IBM SPSS Statistics for Windows, Version 23.0. Armonk, NY: IBM Corp. RESULTS: The one-way analysis of the variance test indicated a significant difference in the fracture strength between the different ceramic groups tested (P=0.037). The Tukey posthoc test showed that the IPS e.max CAD group had marginally higher fracture strength values than the VITA Enamic group (P=055). No significant differences in fracture strength values were found between the VITA Enamic and VITA Suprinity groups or between the VITA Suprinity and IPS e.max CAD groups (P>0.05). CONCLUSION: The reported fracture strength values for all the tested materials were higher than the strength required to resist masticatory forces. Therefore, endocrowns fabricated using VITA Enamic, IPS e.max CAD, and VITA Suprinity CAD/CAM materials present restorations with a clinically acceptable fracture strength.

A Comparative Study of the Marginal Fit of Endocrowns Fabricated From Three Different Computer-Aided Design/Computer-Aided Manufacturing (CAD/CAM) Ceramic Materials: An In Vitro Study.

INTRODUCTION: The marginal seal and adaptation are important factors for successful restoration. An inadequate marginal seal can lead to bacterial microleakage, plaque accumulation, and eventually treatment failure This in vitro study aimed to compare the marginal gap of endocrowns fabricated from three different computer-aided design/computer-aided manufacturing (CAD/CAM) ceramic materials. METHODS: Thirty extracted mandibular molars were selected for the study. Endocrown preparations were completed after root canal treatment. Teeth were divided into three groups to receive endocrowns fabricated of lithium disilicate ceramic (IPS-e.max CAD, Ivoclar Vivadent AG, Schaan, Liechtenstein), zirconia-reinforced lithium silicate ceramic (VITA Suprinity®, VITA Zahnfabrik, Bad Säckingen, Germany), and polymer-infiltrated ceramic (VITA Enamic®, VITA Zahnfabrik). The digital impressions were transferred to the design software to construct the endocrowns. The endocrowns were milled and cemented. The marginal fit was examined using a digital camera stereomicroscope at a magnification of 80X. Images were transferred to Image-J software (National Institutes of Health, Bethesda, Maryland, United States) to measure the marginal gap. RESULTS: One-way ANOVA showed a significant difference in the marginal gap between the different ceramic groups (P=0.006). Tukey's Honest Significant Difference (HSD) post-hoc test showed that VITA Suprinity had significantly higher gap width values than VITA Enamic (P=0.005). No significant differences in gap width values were found between VITA Enamic and IPS e.max CAD or between VITA Suprinity and IPS e.max CAD (P>0.05). CONCLUSION: The marginal gap of endocrown restorations varies with different CAD/CAM materials (zirconia-reinforced lithium silicate glass-ceramic, polymer-infiltrated hybrid ceramic, and lithium disilicate glass-ceramic), but are all within clinically acceptable marginal gap width.

Prosthetically Driven Computer-Guided 1-Piece Zirconia Implant Placement and Restoration Replacing Missing Central Incisor: A Case Report.

Currently, the gold standard material of choice for dental implants is the commercially available pure titanium and titanium alloys. However, this material may have suboptimal anterior esthetic outcome due to the dark grayish burnout. To enhance the esthetic outcomes, zirconium dioxide materials, with reported long-term success in medical uses and tooth-like color, were introduced as a dental implant material. This case report describes the fully guided planning and placement of a 1-piece zirconia implant replacing a missing central incisor. A 21-year-old nonsmoker male patient in excellent general health, presented with a missing tooth #9 (maxillary left central incisor). Straumann PURE (4.1 × 10 mm) Ceramic implant was placed. Three months post-surgery, the soft tissue architecture has been achieved and stabilized, and the healing was satisfactory around the zirconia implant and provisional restoration. The final layered zirconia crown was fabricated. A 2-step cementation technique was used to minimize the excess cement during the final delivery of the crown. After delivery of the final restoration, the patient was followed after 1, 3, 6, and 12 months.

Radiographic Analysis of Posts Performed by Undergraduate Dental Students: A Cross-Sectional Study.

INTRODUCTION: Post and core restorations for endodontically treated teeth must meet certain prosthetic criteria to ensure the success of the final restoration. The aim of this study is to evaluate the quality of posts performed by dental students at King Abdulaziz University Dental Hospital (KAUDH), Jeddah, Saudi Arabia, utilizing periapical radiographs and whether the prosthetic criteria were strictly met by students. MATERIALS AND METHODS: This cross-sectional study included 661 digital periapical radiographs of posts performed by 6th-year dental students from September 2018 to April 2019. The assessment included the following factors: patient's age, patient's gender, tooth type, and arch. Post-related factors including post type, shape, diameter, length, and status of the remaining gutta percha were also evaluated. Statistical analysis was performed using SPSS. Descriptive statistics were generated, and the association between different variables was determined using chi-square test at p<0.05. RESULTS: Posts were used to restore maxillary teeth (67%), and were particularly placed in premolars (44%). The majority of used posts were prefabricated tapered fiber posts (90%). The results were as follows: post diameter equal to one-third of root diameter, 50% met criterion; post length equal to two-thirds of root length, 33%; post length equal to or more than crown height, 93%; absence of space between gutta percha (GP) and post, 74%; and length of the remaining GP equal to 3-5 mm, 68%. Overall, 11% of the posts met all the ideal prosthetics criteria. CONCLUSION: Most qualities of post and core restorations that were radiographically assessed were found to be acceptable and within the recommended prosthodontic criteria.

Conventional and Digital Workflow Planning for Maxillary Teeth Restoration with Porcelain Laminate Veneers: A Clinical Report.

Nowadays, media-influenced patients have the desire to "extremely rapidly" alter their teeth to "ideal" and "too bright" ones. Although some esthetically demanding cases need to be thoroughly planned and treated through prolonged phases, other cases can be handled quickly. In such cases, we can witness the impact of many computer software programs for digital smile design that have penetrated clinical practice. This clinical report describes a conventional and digital step-by-step treatment workflow for restoring anterior maxillary teeth with porcelain laminate veneers. Two digital smile design software (GPS and Nemo DSD 3D) were utilized and compared with the conventional workflow. Feldspathic veneers were chosen for their superior optical properties. Case complexity and operator's experience played a significant role in the selection between the conventional and digital workflow. The advanced digital programs, while having many advantages, are not necessarily superior to the traditional technique. The digital smile design programs used in this case demonstrated an effective and predictable workflow. They can achieve comprehensive digital smile design with a satisfactory esthetic outcome, yet the conventional workflow gave conservative and esthetically pleasing results.

Comparative Evaluation of the Translucency of Monolithic Zirconia.

AIMS AND OBJECTIVES: New techniques are being developed to invent zirconia with high translucency and better esthetics leading to the development of several brands of monolithic zirconia. The aim of this study is to compare the translucency of three brands of zirconia available for the fabrication of monolithic restorations. MATERIALS AND METHODS: An in vitro study was designed to compare the translucency of three brands of zirconia available for the fabrication of monolithic restorations: Zirlux Zirconia (Vivadent Ivoclar), Zenostar Zr Translucent Zirconia (Weiland), and BruxZir Zirconia (Glidewell). All specimens were prepared to 0.5 mm thickness. Thirty zirconia specimens from each material were finished and polished. After drying, specimens were fired according to the manufacturers' recommendations. A spectrophotometer (Color i5) was used for the translucency test. Each specimen was presented at the view port permitting the light to hit the center of the specimen. Results were saved into the software until all measurements were completed. The data were then transferred to an Excel sheet where translucency parameters were calculated. The one-way analysis of variance (ANOVA) test and the post hoc Bonferroni test were performed to analyze the results. RESULTS: The one-way ANOVA test revealed that there was a statistically significant difference between the groups. This study showed lower translucency of BruxZir in comparison to Zenostar and Zirlux when tested under standardized conditions. CONCLUSION: There is a statistically significant difference in the translucency between the different brands of zirconia available for monolithic restoration fabrication. CLINICAL SIGNIFICANCE: Different brands of zirconia have different degrees of translucency. Material selection should be customized in each case.

Management and Restoration of an Implant With Irreversibly Damaged Internal Threads: A Clinical Report.

This report describes a method to restore an implant with irreversibly damaged internal threads. The remaining fractured post from the previous restoration was removed using a combination of an impression coping and an end-cutting bur. An elastomeric impression of the internal surface of the damaged implant, as well as the position of the adjacent implant, was made for fabrication of a new cast post and core and an implant supported 2-unit ceramometal splinted prosthesis.