Dental implant is the device with which a single or multiple missing teeth can be replaced even if support is not there. In this the support is taken from the underlying bone instead of the adjacent teeth unlike fixed bridges. Even complete dentures can be given above the implants even if the severe bone loss is there.
Basically there are two types of dental implants. In some the implants are put inside the bone but some times the thickness or height of the bone is insufficient, so implants can not be put inside the bone. In that case some times implants are put on the bone. The basic two types of dental implants are
1) Endosteal or Root Form Dental Implant
2) Subperiosteal Dental Implant
Endosteal Implants of dental implant is put directly in the bone. It is the most common type of dental implant used in dentistry. It is also called as the root form dental implant as in this type of dental implant the part which is placed inside the bone acts as the root of the natural tooth. They are available in different width varying from 3.2mm to 7mm and are available in different lengths varying from 10mm to18 mm. The width and length is decided by the dentist depending upon the width and the height of the bone and the type and the number of teeth to be replaced. The process of putting the dental implant is two step procedures. In first step a hole is drilled in the bone according to the size of the implant and then the root part of the dental implant is inserted.
Then the gums are sutured above this and patient is asked to wait for 2 to 3 months in which recall evaluation is done to see whether the implant has properly fused with the bone or nor. The process of fusing the implant with the bone is called as the osseointegration. When the dentist is sure that the osseointegration is complete then the second step is done. In which a small incision is given in the gums were the implant is put. The implant is exposed and the abutment part is attached. After this the dentist takes the impression and gets the crown made which is fused o the implant. Some dentist likes to put the Endosteal dental implant as the one step procedure. In one step procedure the only difference is the part of the implant o which the abutment is placed is kept above the gum margin. So that when the healing is completed and the abutment has to be attached then the second incision is not given to expose the dental implant as it is already above the gum margin. Now which procedure should be done depends upon the dentist. Some are comfortable with the two step procedure and some are happy with the one step procedure. The success and failure of the implant does not depend upon this.
Some times when the dentist feels that the bone height is not ideal he do some special surgeries before giving the dental implants these are
Bone Grafting - in this if the height of the bone is insufficient then bone is taken from some other part like jaw or the hip bone is used. Some times synthetic bone graft material is also used.
Tissue Regeneration - A artificial membrane can be placed near the bone edge to enhance the proper healing after the bone graft.
After these surgeries when the bone height and thickness is ideal the Endosteal dental implant is put.
Subperiosteal Dental Implant – Some times the bone structure is badly atrophied. Not only it is atrophied but the bone structure is limited to the extent that bone grafting can not be done. In that case subperiosteal bone graft is given which is individually made and is very light weight. It is a metal frame work which has multiple posts which come out of the gum tissues and is put on the remaining bone. The dentist has to decide where it can be put depending upon the site and the condition of the bone. It can be used to replace the multiple teeth or even complete denture can be given above this. After it is put the natural bone and the tissue covers it and give it extra stability.
Ramus Frame Implant - Some time when the lower jaw bone is severely resorbed and is unable to give any kind of retention then there is another alternative known as Ramus frame implant. It is in between the Subperiosteal and the plate form. These are prefabricated and can be moulded according to the anatomy. It is given on both sides on the ramus of the bone posteriorly. The part which shows the opening is inside the bone but the metal bar is outside in the oral cavity towards the tongue and holds the denture.
Intramucosal Implant – This is another type which is not used very often known as Intramucosal Implant. It is used to give extra retention and stability to the removable dentures. In this a mushroom shaped attachment is attached on the gum side of the denture and it fits in the indentations which are made I the soft tissue it increases the retention of the removable dentures.
Dental Implants come in different shapes and textures.
Materials for Dental Implants
Different materials are used for dental implants but in dentistry most commonly used dental implant is of Titanium as it is most compatible witht he dental tissues and inert. The various materials used for dental implants are as under.
3. Alloys of titanium/ aluminium/ vanadium
4. Cobalt,/ chromium/ molibidnum
5. Aluminium oxide
7. Silicon rubber
8. PMMA( polymetyhl methacrylate)
Components of Dental Implant
2. Cover screw
3. Healing abutment
5. Impression posts
6. Laboratory analogs
7. Waxing sleeves
8. Prosthesis retaining screws
Functions of Dental Implant
Implant Body - It is a portion of implant system within the bone.
Cover Screw - It seals the occlusal surface of the implant during osseointrgration( the interface between the alloplastic material and the living tissue)
Healing Abutment - It is a cover attathed to the implant which is used to maintain the opening through the tissue until the restoration is completed.
Abutments - They are the components of the implant system that screw directly into the implant.There are diiferent types of abutments available like standard,fixed, angled, tapered and nonsegmented.
Impresssion Posts - They are the component used during the impression procedure to transfer the position of the implant to the cast.
Lab Analog - Made to represent exactly the top of the implant fixture in the laboratory cast.
Waxing Sleeves - They are attatched to the abutment by the relating screw on the laboratory model.
Prosthesis Retaining Screw - Screw used to secure a screw- retained metal framework.