LEC 18 Dental Material Dental Implants Dr. Zainab Al-Raheem Dental implant: is medical device, made of one or more biomaterials that is placed in the mandible or maxilla to support a reconstruction of missing teeth. Types of implants 1- Sub-periosteal implants Implants which are typically lie on top of the jaw bone but underneath gum tissue. The important distinction is that they usually do not penetrate into jaw. This type of implant used in complete denture This type is placed under the periosteum and against bone, rather than within alveolar bone. This modality is used in cases of advanced alveolar resorption in which the volume of the residual bone available is insufficient for the insertion of an endosteal implant. The sub-periosteal implant is retained by periostael integration, in which the outer layer of the periosteum provides dense fibrous envelopment and anchors the implant to bone through Sharpey’s Fibers and also by retentive undercut features of implant design. Total sub-periostael implants are for patients who have lost all of their teeth in one arch. Such treatment is not considered main stream but can be performed after experience with a number of unilateral or inter-dental cases. Properties of sub-periosteal implant I. Designed where residual bone is less than 8 mm II. Mainly in mandible and less fro maxilla III. Support an over denture IV. Need computer generated model V. Cobalt chromium, stainless steel, or titanium alloy 2- Trans-osseous implants Implants which are similar in definition to endosseous implants in that they are surgically inserted into the jaw bone. However, these implants actually penetrate the entire jaw so that they emerge opposite to entry site, usually at the bottom of the chin. It is used mostly in case of flat lower ridge. A reconstructive device placed through a sub-mental incision and attached to the mandible with multiple fixation and two transosteal screws to support a full arch prosthesis. Transostael implants are the most surgically invasive technique sensitive. They are limited to the mandible. Although transosteal implants have proven safety and efficiency. Properties I. At least 10mm bone height needed II. Only in the mandible III. External incision of the sub-mental region IV. 5-7 parallel holes in base of mandible with only 2 pins appear in the mouth V. Usually support an over denture 1 3- Endosseous implants Implants that are surgically inserted into the jaw bone. The endosteal dental implant defined as device placed into the alveolar and/or basal bone of the mandible or maxilla and transecting only one cortical plate. It is used for partial and single tooth replacement. Endosteal implants are placed within fully or partially edentulous alveolar ridges with sufficient residual bone available to accommodate the selected configuration. Some ednosteal implants are attached to components for retention of a fixed or removable prosthesis. Endosteal implant systems are commonly referred to as one stage or two stages There are three forms of endosseous implants: I. Blade (or plate) form II. Ramus frame implant III. Root form implants Blade (or Plate) form implants 2 Ramus frame implant Root from implant 3 Root form implants - Root form implants are designed to resemble the shape of a natural tooth root. They are usually circular in cross section. Root from can be threaded, smooth, stepped, parallel sided or tapered, and can be joined to a variety of components for retention of a prosthesis As a rule, root froms must achieve osseointegration to succeed. Therefore, they are placed in a nonfunctional state during healing until they osseoinegtrated. A root form can be placed anywhere in the mandible or maxilla where there is sufficeient bone available. Mechanical structure of root form implant 1- The fixture: is the component which is surgically placed into the jawbone, it is made of pure titanium with machined threads on the outer surface as well as inner channel. 2- The cover screw: it is screwed into the top of the fixture to prevent down growth of soft and hard tissue into the internal threaded area. It acts as a seal on the coronal portion of the fixture. 3- The abutment: it is the transmucosal component which is connected into the fixture using an abutment screw. It is made of titanium in a cylindrical shape. 4- The abutment screw: inserted through the abutment and threads into the fixture to connect the two components 5- The gold cylinder: an integral part of the final prosthesis, it is connected to the abutment with gold screw. 6- The gold screw: inserted through the gold cylinder and threads into the abutment screw to connect the gild cylinder and abutment. Mechanical structure of root form implant 4 Osseointegration: is defined as "the formation of a direct interface between an implant and bone, without intervening soft tissue". Osseointegrated implant: is a type of implant defined as "an endosteal implant containing pores into which osteoblasts and supporting connective tissue can migrate" Bioactive retention can be achieved in cases where the implant is coated with bioactive materials such as hydroxyapatite. These bioactive materials stimulate bone formation leading to a physico-chemical bond. The implant is ankylosed with the bone. 5 6
