RESUMO
PURPOSE: To assess the effects of tilted external hexagon implants and splinted restorations in terms of stress distribution on the bone tissue, implants, and prosthetic screws, using three-dimensional finite element analysis. MATERIALS AND METHODS: Six models were used to simulate a posterior maxilla bone block (type IV) from the first premolar to the first molar. Each model included three 4.1-mm-diameter external hexagon implants with varying inclinations (0°, 17°, and 30°) and crown designs (splinted and nonsplinted restorations). The forces applied were as follows: 400 N axially (50 N for each slope of the cusp) and 200 N obliquely (45° only on the buccal slope of the cusp). Stress distribution on the implants and prosthetic screw was evaluated using Von Mises stress, while the maximum principal stress was used to evaluate the stress distribution in the bone tissue. RESULTS: The oblique load increased the stress on all the structures in all the models. Increased inclination of the implants resulted in higher stress concentration in the bone tissue, implants, and prosthetic screws. However, splinted restorations contributed to reduction of the stress for the oblique loading, mainly in the bone tissue and prosthetic screw of the first molar, as the stress was shared between the first and second premolar restorations. CONCLUSIONS: Tilted implants increased proportionally the stress on bone tissue and prosthetic screws of models. Additionally, splinting restorations reduced the stress concentration area in the simulated bone tissue, implants, and prosthetic screws in the first molar, as the stress was shared with the adjacent implants.
Assuntos
Implantes Dentários , Maxila , Análise de Elementos Finitos , Maxila/cirurgia , Prótese Dentária Fixada por Implante/métodos , Análise do Estresse Dentário , Estresse Mecânico , Fenômenos BiomecânicosRESUMO
STATEMENT OF PROBLEM: Whether providing an occlusal device for a patient with bruxism and an implant-supported fixed dental prosthesis leads to improved biomechanics is unclear. PURPOSE: The purpose of this 3D finite element analysis (FEA) study was to evaluate the biomechanical behavior of 3-unit implant-supported prostheses under parafunctional forces with and without an occlusal device. MATERIALS AND METHODS: Eight 3D models consisting of a posterior (type IV) maxillary bone block with 3 external hexagon implants (Ø4.0×7.0 mm) and 3-unit implant-supported prostheses with different crown connections (splinted or unsplinted) and an occlusal device under functional and parafunctional loading were simulated. The abutment screws were evaluated by von Mises stress maps, and the bone tissue by maximum principal stress and microstrain maps by using a finite element software program. RESULTS: An occlusal device improved the biomechanical behavior of the prostheses by reducing stress in the abutment screws and stress and strain in the bone tissue. However, the use of an occlusal device was not sufficiently effective to negate the biomechanical benefit of splinting. CONCLUSIONS: The use of splinted crowns in the posterior maxillary region with an occlusal device was the most effective method of reducing stress in the abutment screws and stress and strain in the bone tissue when parafunction was modeled.
Assuntos
Implantes Dentários , Prótese Dentária Fixada por Implante , Fenômenos Biomecânicos , Coroas , Planejamento de Prótese Dentária , Análise do Estresse Dentário , Análise de Elementos Finitos , Humanos , Estresse MecânicoRESUMO
CONTEXT: Is it possible that the irrigating solutions can have the potential to cause post-operative pain? Unfortunately, the current literature does not provide clear guidance. AIM: The purpose of this systematic review and meta-analysis was to comprehensively review two different irrigation solutions (sodium hypochlorite and chlorhexidine) regarding the post-operative pain after endodontic treatment. SETTINGS AND DESIGN: This study was prepared according to the Cochrane criteria for creating a systematic review and meta-analysis and confirms the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. MATERIAL AND METHODS: This search was conducted in the PubMed/MEDLINE, SCOPUS and Cochrane Library databases until February 2018 to answer the In [(Population) what is the effect of (Intervention) on (Outcome), compared with (Comparison) Intervention] (PICO) question: could sodium hypochlorite cause more post-operative pain than chlorhexidine in teeth subjected to endodontic treatment? The primary outcome was overall post-operative pain after 24 h. RESULTS: After applying the inclusion and exclusion criteria, three randomized clinical trials fulfilled the eligibility criteria, and two were subjected to the meta-analysis. There was no difference in post-operative pain between the tested irrigating solutions. CONCLUSIONS: There are few studies published in the current literature; therefore, additional randomized clinical studies are required to on this topic to help clinicians make the best decision concerning treatment.