ABSTRACT
RESUMEN: Factores como el tipo de resina compuesta y sistema de matrices son clave para lograr una adecuada intensidad del punto contacto, la cual puede determinar el éxito de una restauración clase II. Con el objetivo de comparar la intensidad del punto de contacto obtenida en restauraciones de resina clase II, cuando se usan diferentes consistencias de resinas compuestas y sistemas de matrices en estudios in vitro, se realizó una revisión sistemática según la pauta PRISMA. Los estudios fueron seleccionados a través de una estrategia de búsqueda para cada base de datos electrónica (MEDLINE/ PubMed, Scopus, Web of Science y EBSCO host). En cada artículo seleccionado, se tabularon: autor/año, tamaño muestral, diente utilizado y preparación cavitaria, tipo de resina compuesta, tipo de sistema matriz e intensidad del punto de contacto (resultado medido en Newton). La calidad metodológica se analizó mediante una pauta modificada para estudios in vitro. De 90 artículos, un total de 5 artículos reunieron los criterios de selección y fueron incluidos. De estos cinco artículos, sól o dos artículos estudiaron la influencia de la consistencia de la resina compuesta y los sistemas de matrices en forma simultánea. El riesgo de sesgo para los estudios fue bajo para 1 artículo, medio para 2 y alto para los otros 2 artículos. No se obtiene la misma intensidad de punto de contacto entre diferentes consistencias de resina compuesta y distintos sistemas de matrices, ya que los mayores valores se obtuvieron al utilizar matrices seccionales combinadas con anillo de separación y resinas compuestas de mayor viscosidad.
ABSTRACT: Factors such as the type of composite resin and matrix system are key to achieving an adequate proximal contact tightness, which can determine the success of a class II restoration.To compare the proximal contact tightness obtained in class II resin restorations, when different consistencies of composite resins and matrix systems are used, on in vitro studies. The systematic review was carried out according to the PRISMA Statement guidelines. The studies were selected through a search strategy for each electronic database (MEDLINE/PubMed, Scopus, Web of Science and EBSCO host). In each selected article, the following were tabulated: author/year, sample size, tooth used and cavity preparation, type of composite resin, type of matrix system and proximal contact tightness (result measured in Newton). The methodological quality was analyzed using a modified guideline for in vitro studies. Of 90 articles, a total of 5 articles met the selection criteria and were included. Of these five articles, only two articles studied the influence of the consistency of the composite resin and the matrix systems simultaneously. One of the articles was a low risk of bias, two of medium and two of high. The same proximal contact tightness is not obtained between different consistencies of composite resin and different matrix systems, since the highest values were obtained when using sectional matrices combined with a separation ring and composite resins of higher viscosity.
ABSTRACT
STATEMENT OF PROBLEM: Several prosthetic options are available for the restoration of multiple adjacent implants. A passively fitting prosthesis has been considered a prerequisite for the success and maintenance of osseointegration. Passivity is a particular concern with multiple implants because of documented inaccuracies in the casting and soldering process. One way to avoid this problem is to restore the implants individually, however, the restorations of individual adjacent impants requires careful adjustment of interproximal contacts. PURPOSE: The purpose of this study was to compare the stress distribution pattern and amount surrounding Bicon implants with individual crowns and splinted restorations. MATERIAL AND METHOD: A photoelastic model of a human partially edentulous left mandible with 3 Bicon implants(4*1 mm) was fabricated. For non-splinted restorations, individual crowns were fabricated on 3 abutments (4.0*6.5 mm, 0 degree, 2.0 mm post, Bicon Inc., Boston, USA) After the units were cemented, 4 levels of interproximal contact tightness were evaluated: open, ideal (8 micrometershim stock drags without tearing), medium(40 micrometer), and heavy(80 micrometer). Splinted 3-unit fixed partial dentures were fabricated and cemented to the model. Changes in stress distribution under simulated non-loaded and loaded conditions(7.5, 15, 30 lb) were analyzed with a circular polaricope. RESULTS: 1. Stresses were distributed around the entire body of fin in Bicon implants. 2. Splinted restorations were useful for distribution of stress around implants especially with higher loads. 3. By increasing the contact tightness between the individually restored three implants, the stress increased in the coronal portion of implants. CONCLUSIONS: Ideal adjustment of the contact tightness was important to reduce the stresses around individually restored Bicon implants.
Subject(s)
Humans , Crowns , Denture, Partial, Fixed , Mandible , Osseointegration , Prostheses and Implants , SplintsABSTRACT
STATEMENT OF PROBLEM: A difficulty in achieving a passive-fitting prosthesis can be overcome by individual crown restoation of multiple implants. But individualized crown has another difficulty in control of contact tightness and stress distribution. PURPOSE: This in vitro study is to evaluate the stress distribution and the magnitude in the supporting tissues around Endopore implants with different crown lengths, interproximal contact tightness, and the splinting effects. MATERIAL & METHODS: Three Endopore implants(4.1*9 mm) were placed in the mandibular posterior edentulous area distal to the canine and photoelastic model was made with PL-2 resin(Measurements Group, Raleigh, USA). Restorations were fabricated in two crown lengths: 9, 13 mm. For non-splinted restorations, individual crowns were fabricated on three custom-milled titanium abutments. After the units were cemented, 4 levels of interproximal contact tightness were evaluated: open, ideal(8 micrometershim stock drags without tearing), medium(40 micrometer), and heavy(80 micrometer). For splinted restorations, 3-unit fixed partial dentures were fabricated. This study was examined under simulated non-loaded and loaded conditions(6.8 kg). Photoelastic stress analysis was carried out to measure the fringe order around the implant supporting structure. RESULTS: 1. When restorations were not splinted, the more interproximal contact tightness was increased among the three implants, the more stress was shown in the cervical region of each implant. When crown length was increased, stresses tended to increase in the apex of implants but there were little differences in stress fringes. 2. When nonsplinted restorations were loaded on the first or third implant, stresses were increased in the apex and cervical region of loaded implant. Regardless of interproximal contact tightness level, stresses were not distributed among the three implants. But with tighter interproximal contact, stresses were increased in the cervical region of loaded first or third implant. 3. When the nonsplinted restorations were not loaded, there were little stresses on the supporting structure of implants, but low level stresses were shown in the splinted restorations even after sectioning and soldering. 4. With splinted restorations, there were little differences in stresses between different crown lengths. When splinted restorations were loaded, stresses were increased slightly on the loaded implant, but relatively even stress distribution occurred among the three implants. CONCLUSIONS: Splinting the crowns of adjacent implants is recommended for Endopore implants under the overloading situation.