Influence of prosthetic index structures and implant materials on stress distribution in implant restorations: a three-dimensional finite element analysis.

BACKGROUND: Mechanical complications affect the stability of implant restorations and are a key concern for clinicians, especially with the frequent introduction of new implant designs featuring various structures and materials. This study evaluated the effect of different prosthetic index structure types and implant materials on the stress distribution of implant restorations using both in silico and in vitro methods. METHODS: Four finite element analysis (FEA) models of implant restorations were created, incorporating two prosthetic index structures (cross-fit (CF) and torc-fit (TF)) and two implant materials (titanium and titanium-zirconium). A static load was applied to each group. An in vitro study using digital image correlation (DIC) with a research scenario identical to that of the FEA was conducted for validation. The primary strain, sensitivity index, and equivalent von Mises stress were used to evaluate the outcomes. RESULTS: Changing the implant material from titanium to titanium-zirconium did not significantly affect the stress distribution or maximum stress value of other components, except for the implant itself. In the CF group, implants with a lower elastic modulus increased the stress on the screw. The TF group showed better stress distribution on the abutment and a lower stress value on the screw. The TF group demonstrated similar sensitivity for all components. DIC analysis revealed significant differences between TF-TiZr and CF-Ti in terms of the maximum (P < 0.001) and minimum principal strains (P < 0.05) on the implants and the minimum principal strains on the investment materials in both groups (P < 0.001). CONCLUSIONS: Changes in the implant material significantly affected the maximum stress of the implant. The TF group exhibited better structural integrity and reliability.

Advances in ceramics for tooth repair: From bench to chairside.

OBJECTIVES: To give a comprehensive review of advancement in dental ceramics, fabrication methods, and the challenges associated with clinical application. DATA, SOURCES AND STUDY SELECTION: Researches on chemical composition, biomechanical behaviors, optical properties, bonding strategies and fabrication methods were included. The search of articles was independently conducted by two authors in the PubMed, Scopus, Medline and Web of Science. CONCLUSIONS: Dental ceramics have shown significant advancements in terms of esthetics and function. However, improving fracture toughness without compromising optical properties remains a challenge. Repairing fractured zirconia or glass-matrix ceramic prostheses with the same material is difficult due to the sintering process. Developing innovative bonding techniques that provide strong and long-lasting bonding strength between ceramics and tooth structures poses a recurring obstacle. CLINICAL SIGNIFICANCE: Despite the emergence of dental ceramics and fabrication techniques, certain limitations such as susceptibility to brittleness and fracture still exist. Therefore, the current review provided valuable information around the advanced dental ceramics in tooth repair. The laboratory test data and the clinical outcome are also presented in details, aiming to guide clinicians in making informed decisions regarding ceramic restorations.

Three-dimensionally printed implant surgical guide-related experience, knowledge, attitude, and professional behaviors among 2028 dentists in China: A cross-sectional study.

STATEMENT OF PROBLEM: Research on the current place of 3-dimensionally printed implant surgical guides (3D-ISGs) among practicing dentists worldwide is lacking, with little research focused on dentists' experience, knowledge, attitude, or professional behavior related to 3D-ISG or on the main obstacle to adoption. PURPOSE: The purpose of this cross-sectional study was to identify the adoption of 3D-ISG in dental practice in China and to determine factors that influence its further application and dentists' attitudes and willingness. MATERIAL AND METHODS: Semistructured questionnaires were sent to a sample of Chinese dentists composed of users and nonusers of 3D-ISG. The questionnaires were displayed and distributed through a professional online survey system (http://www.wjx.cn) and a social media platform (WeChat). The responses were analyzed with multivariable generalized equations, and the effect of various demographic variables was determined, including dentist experience, academic degree, and type of practice (public or private). RESULTS: A total of 2028 valid questionnaires were collected. In dental practice, 39.3% of the respondents used 3D-ISG. Respondents with a PhD (62.4%) used the 3D-ISG more than twice as frequently as respondents with a junior college degree or below (31.8%). The majority of the members of implantology departments (81.7%) applied 3D-ISG, but doctors in other departments used it at a rate of less than half. The 3D-ISG was most frequently used in the maxillary anterior area (78.4%), followed by the edentulous maxilla and mandible (61.0% and 60.5%, respectively). The main barriers were high initial cost, complex and time-consuming digital design, and lack of expertise in the proper use of 3D-ISG. CONCLUSIONS: Most dentists did not use 3D-ISG in dental practice. The 3D-ISG application rate was significantly associated with sex, academic degree, years of dental practice, department, monthly income, and type of healthcare facility. To improve the popularity of 3D-ISG, particularly among dentists without advanced degrees, it would be important to optimize the digital design software program and provide sufficient training.

Prefabricating Implant-supported Interim Prosthesis from CBCT Scans: a Case Report of Digital Immediate Implant Restoration.

This clinical report describes the immediate implant placement and restoration for a 47-yearold woman with a protruded and loose maxillary right central incisor. The treatment included minimally invasive extraction, flapless immediate implant placement using a fully guided surgical template, and immediate implant-supported provisionalisation. The interim anatomical prosthesis was fabricated in advance based on preoperative CBCT scans, and the digital technique made it possible to integrate data precisely from different sources. After 6 months of provisionalisation, satisfactory gingival aesthetic and functional improvements were achieved, followed by a definitive screw-retained zirconia restoration. Thus, application of a complete digital workflow could reduce chairside time and create an optimal emergence profile that matches the residual bone architecture of the extraction sites with minimal interference.

Effect of universal adhesive and silane pretreatment on bond durability of metal brackets to dental glass ceramics.

This study aimed to investigate the effect of universal adhesive and silane pretreatment on the bond durability of metal brackets to dental glass ceramics. Eighty lithium disilicate glass ceramic specimens were randomly assigned to one of four groups (n = 20) defined by the pretreatment and adhesive used: (i) Adper Single Bond 2; (ii) silane + Adper Single Bond 2; (iii) Single Bond Universal; and (iv) silane +Single Bond Universal. Maxillary central incisor metal brackets were bonded on the ceramic surfaces with resin composite. A shear bond strength test was conducted after 24 h of water storage and after 10,000 thermocycles. Adhesive remnant index scoring and field-emission scanning electron microscopy were performed to determine adhesives remaining on the ceramic surfaces and the ceramic ultrastructure following bracket debonding, respectively. After 10,000 thermocycles, specimens treated with Single Bond Universal preserved an appropriate bond strength between brackets and glass ceramics and showed minimum ceramic surface damage following bracket debonding, which was not the case in the other three groups. The application of a silane-containing universal adhesive without silane pretreatment achieves adequate durability of the bond of metal brackets to dental glass ceramics and allows safe debonding, which may aid in optimizing the effectiveness for orthodontic treatment.