ABSTRACT
BACKGROUND: Overdenture supported by two to four implants located in the mandibular mental foramen area has been widely used in edentulous patients. However, in patients with severe mandibular resorption, it is a challenging to insert conventional implants. Mini-implants are a better choice in these cases. OBJECTIVE: To compare and analyze the biomechanical characteristics of conventional and mini-implants supported mandibular complete overdenture and to reveal the influence of different implant repair methods on implants and its surrounding tissues. METHODS: The cone beam CT data of a healthy patient scheduled to receive complete edentulous implant supported overdenture was obtained. CT data of the patient, implant and attachment data were imported into the software to create four models: 2 normal implants, 4 normal implants, 4 mini implants, and 5 mini implants supported mandibular overdentures respectively. The overdenture was bilaterally subjected to a vertical load of 150 N. The displacement and stress of implants and the stress of bone were compared. RESULTS AND CONCLUSION: For all models, the lowest and highest maximum values of stress in bone were obtained from 4 normal implant model (2.71 MPa) and 4 mini implant model (7.93 MPa). The lowest and highest maximum values of displacement in implant were obtained from 4 normal implant model (1.37 µm) and 2 normal implant model (1.57 µm). Moreover, the lowest and highest maximum values of stress in implant were demonstrated from 4 normal implant model (12.90 MPa) and 4 mini implant model (22.17 MPa). The biomechanical values of mini implant models were higher than those of conventional models. The biomechanical values of all models were below the critical limits. The distribution was more homogenous and the maximum values of displacement in the implant, stress in implant and stress in bone were reduced as the number of implants increased. Three-dimensional finite element analysis revealed that mandibular overdenture supported by four or five mini implants is a reliable treatment option.
ABSTRACT
Purpose: The purpose of this research was to compare stress distribution on the bone between single implant‑retained and two‑implant‑retained mandibular overdentures using three‑dimensional (3D) finite element analysis. Materials and Methods: Two 3D finite element models were designed. The first model included single implant‑supported mandibular overdenture placed in the midline of the mandible while the second model included two‑implant‑supported mandibular overdenture placed in the intra‑foramen region, retained by ball attachment of the same diameter. The bone was modeled on the D2 bone depending on the classification given by Misch. A computed tomography scan of the mandible was used to model the bone by plotting the key points on the graph and generating the identical key points on the ANSYS Software (ANSYS, Inc., USA). The implant was modeled using appropriate dimensions as provided by the manufacturer. Stresses were calculated based on the von Mises criteria. Results: Stresses produced in the hard bone (HB) and soft bone (SB) were higher in single implant‑retained mandibular overdenture while stresses produced around the denture as well as implant were higher in two‑implant‑retained mandibular overdenture. Conclusion: Within the limitations of the study, it had been seen that stresses produced were the highest on HB and SB in single implant‑retained mandibular overdenture while stresses produced across the denture as well as implant were the highest in two‑implant‑retained mandibular overdenture.
ABSTRACT
PURPOSE: To present a literature review on implant overdentures after a brief survey of bone loss after extraction of all teeth. MATERIALS AND METHODS: Papers on alveolar bone loss and implant overdentures have been studied for a narrative review. RESULTS: Bone loss of the alveolar process after tooth extraction occurs with great individual variation, impossible to predict at the time of extraction. The simplest way to prevent bone loss is to avoid extraction of all teeth. To keep a few teeth and use them or their roots for a tooth or root-supported overdenture substantially reduces bone loss. Jaws with implant-supported prostheses show less bone loss than jaws with conventional dentures. Mandibular 2-implant overdentures provide patients with better outcomes than do conventional dentures, regarding satisfaction, chewing ability and oral-health-related quality of life. There is no strong evidence for the superiority of one overdenture retention-system over the others regarding patient satisfaction, survival, peri-implant bone loss and relevant clinical factors. Mandibular single midline implant overdentures have shown promising results but long-term results are not yet available. For a maxillary overdenture 4 to 6 implants splinted with a bar provide high survival both for implants and overdenture. CONCLUSION: In edentulous mandibles, 2-implant overdentures provide excellent long-term success and survival, including patient satisfaction and improved oral functions. To further reduce the costs a single midline implant overdenture can be a promising option. In the maxilla, overdentures supported on 4 to 6 implants splinted with a bar have demonstrated good functional results.
Subject(s)
Humans , Alveolar Bone Loss , Alveolar Process , Denture, Overlay , Dentures , Jaw , Jaw, Edentulous , Mandible , Mastication , Maxilla , Patient Satisfaction , Prostheses and Implants , Quality of Life , Splints , Tooth , Tooth ExtractionABSTRACT
Objetivo: avaliar e comparar o nível de satisfação de pacientes que receberam próteses totais convencionais (PTC) ou overdentures implantorretidas (OIR) estabilizadas com attachment bola na região mandibular. Material e Métodos: aplicação de questionário composto por fatores de satisfação (adaptação, retenção, mastigação, fonética, conforto, condições de higienização, estética e autoestima) e por níveis de satisfação (insatisfeito, satisfeito e muito satisfeito), em 124 pacientes com idade média de 55 anos, divididos em dois grupos: grupo PTC (n = 60) e grupo OIR (n = 64). Resultados: os dados obtidos foram analisados através de análise estatística descritiva e inferencial (teste de Mann-Whitney) e mostraram que os pacientes que receberam OIR demonstraram maior satisfação em todos os fatores avaliados (p < 0,05). Conclusão: a OIR proporciona maior satisfação aos pacientes quando comparada com a PTC; no entanto, há necessidade de mais estudos comparativos em relação a seleção das amostras e aplicação de outros instrumentos de avaliação
Objective: the aim of this study was to evaluate and compare satisfaction levels of patients receiving conventional dentures (CDS) or implant-retained mandibular overdentures (IROVD) with ball attachments. Material and Methods: one-hundred and twenty four patients (mean age 55 years) were divided into two groups: CD (n = 60) and IROVD (n = 64). A questionnaire consisting of several factors (adaptation, retention, chewing, phonetics, comfort, oral hygiene, esthetics, and self-esteem) and levels of satisfaction (unsatisfied, satisfied, and very satisfied) was applied. Descriptive and inferential statistics (Mann-Whitney) were performed. Results: IROVD patients demonstrated greater satisfaction for all factors evaluated (p < 0.05). Conclusion: the IROVD provides better results than CDS. However, there is a need for more comparative studies regarding sample selection and the use of other evaluation instruments.
Subject(s)
Humans , Male , Female , Middle Aged , Denture, Complete , Patient SatisfactionABSTRACT
objective: To observe the effectiveness of vertical easy ball attachments (VEBA) in removable partial denture with metal base. Methods: Removable partial denture was retained with one or two sets of VEBA attached to full metal crown or porcelain fused to metal crown in 12 patients and 6～24 month clinical follow up was carried out. Results: All removable partial dentures retained with VEBA had good retention, stabilization, function and esthetic outcome, all the patients were greatly satisfied. Conclusion: VEBA has strong retentive force and protects abutments, it is a promising retainer in removable partial denture.
ABSTRACT
One of the biggest clinical problems of osseointegrated implant prosthesis is the excessive stress caused by bite forces which are transfered directly into the bone through the osseointegrated implant fixtures. So several biodynamic problems occur when there is an excessive fatigue stress. The factors of stress distribution are the number, kind, position, arrangement of the implants, and the distance between the implants, and the kind, quality of superstructure prosthesis and connection type between the rest implant and the superstructure. Recently, a distal short additional implant, socalled rest implant, is employed to reduced the stresses in conventional cantilevered prostheses. This study was undertaken to analyze the stresses transfered by osseointegrated implant cantilevered prostheses depending upon the number and the position of implants, the presence of rest implant, and the type of their connection. Three dimensional finite element analysis was attempted using ANSIS ver. 5.3 program under IBM INDIGO computer. The results were as follows 1. The rest implant influenced on the pattern of stress distribution on the anterior area of the mandible and the superstructure. 2. In the group employing the rest implants, the fixed type of connection between the rest implant and the superstructure was more stable than the ball attachment type on the stress distribution. 3. In the group employing the ball attachment between the rest implant and the superstructure, the case with 4-implants(on canine, premolar) was little more stable than the case with 6-implants and the case with 4-implants (on incisor, premolar) on the stress distribution. 4. In the cantilevered group, the case with 4-implants(on incisor, premolar) and the case with 6-implants were more stable than the case with 4-implants (on canine, premolar) on the stress distribution. 5. In all of the group, the case with 6-implants and the fixed type of connection was the most stable and the case with 4-implants (on canine, premolar) was the most unstable on the stress distribution.