title: Maxillary "All-On-Four" treatment using zygomatic implants. A mechanical analysis.
abstract: OBJECTIVE
  Zygomatic implants may be used for dental rehabilitation in atrophic maxillae. The aim of this study was to establish experimentally the areas of stress distribution using 2 kinds of "All-On-Four" maxillary procedures.
  
  
  METHODS
  The best position to insert the implants was selected using polyurethane craniomaxillary models and surgical guides were made. Group 1 was designed with two posterior zygomatic implants and two conventional anterior implants, and group 2 with two posterior zygomatic implants and two anterior zygomatic implants. A titanium bar was built to link the 4 implants in both groups. Photoelastic replicas of these models were made and the implants were inserted using the surgical guides. An Instrom 4411 testing machine was used to perform a unilateral compressive loading at the level of the right first molar until 2mm of displacement was obtained.
  
  
  RESULTS
  Group 1 showed a high strain concentration in the right lateral orbital region at the level of the apex of the zygomatic implant. Less strain was noticed at the apical levels of the conventional implants in the anterior sector and of the contralateral zygomatic implant. Group 2 showed high strains in the lateral inferior orbital area. The load was low in the alveolar bone sector.
  
  
  CONCLUSIONS
  Zygomatic bone and paranasal structures are loaded at high levels when zygomatic implants are used to stabilize a full maxillary prosthodontic rehabilitation on 4 implants. The use of 4 zygomatic implants loads the alveolar bone to a lower extent and seems better suited from a mechanical point of view than the use of 2 zygomatic implants.
authors.affiliation: Division of oral and maxillofacial surgery, State University of Campinas, Piracicaba, Brazil.
authors.forename: P H
authors.initials: PH
authors.lastname: de Moraes
authors.affiliation: Division of oral and maxillofacial surgery, Universidad de La Frontera, Claro Solar 415-A, Temuco, Chile; Center for biomedical research, Universidad Autónoma de Chile, Temuco, Chile. Electronic address: sergio.olate@ufrontera.cl.
authors.forename: S
authors.initials: S
authors.lastname: Olate
authors.affiliation: Division of prosthesis and periodontics, State University of Campinas, Piracicaba, Brazil.
authors.forename: M de Arruda
authors.initials: Mde A
authors.lastname: Nóbilo
authors.affiliation: Division of oral and maxillofacial surgery, State University of Campinas, Piracicaba, Brazil.
authors.forename: L
authors.initials: L
authors.lastname: Asprino
authors.affiliation: Division of oral and maxillofacial surgery, State University of Campinas, Piracicaba, Brazil.
authors.forename: M
authors.initials: M
authors.lastname: de Moraes
authors.affiliation: Division of oral and maxillofacial surgery, State University of Campinas, Piracicaba, Brazil.
authors.forename: J de Albergaría
authors.initials: Jde A
authors.lastname: Barbosa
mesh_terms: D001696:Biomechanical Phenomena; D003758:Dental Implantation, Endosseous / Q000295:instrumentation* / Q000379:methods*; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported / Q000009:adverse effects; D006801:Humans; D007575:Jaw, Edentulous / Q000601:surgery; D008422:Materials Testing / Q000379:methods; D008437:Maxilla / Q000601:surgery*; D013314:Stress, Mechanical; D015050:Zygoma / Q000601:surgery*
keywords: Dental implants; Implants dentaires; Mechanical; Stress; Stress mécanique; Zygomas