The different types of implants and materials
Introduction : Dental implants come in a wide range of morphologies. The implant must integrate with its bone environment and soft tissues to best guide their adaptation to the future prosthesis.
Implants differ in their shape, surface condition and prosthetic connection system.
1-The choice of implants depends
-available bone volume,
-bone quality
-aesthetic imperatives
-mechanical constraints
-residual prosthetic space
2-Different types of implants
A- Shape of implants: we define implant morphology according to:
-the shape of the body (cylindrical or conical)
-the shape of the collar (cylindrical or flared)
-its architecture (in one part or in two parts)
A-section of an implant
- implant body
a-Shape of the implant body
1- Cylindrical screw implants or standard screws: Cylindrical implants have a threaded body (external thread over the entire height of its body) and are offered by manufacturers in different lengths and different diameters (corresponding to the external diameter of the coils). Their neck generally has a smooth surface 1 to 3 mm high.
These implants can have either a cervical diameter identical to the body of the implant or a cervical flare and a truncated and secant apex.
The choice of the standard screw implant shape with a flared cervical plateau is preferred because it improves the primary stability of the implant in the case of low-density bone or immediate extraction-implantation.
Some implants have a greater cervical flare and are particularly indicated for molar rehabilitation, in cases where the crestal bone volume does not allow the placement of a large diameter implant, because they improve function and aesthetics.
The body of the implant is perfectly cylindrical and the corresponding drills are also cylindrical. This shape allows for considerable room for maneuver during drilling as well as during implant positioning. The position of the implant in its socket is easily modifiable. An implant that is too buried can be unscrewed by half a turn if a more coronal position is deemed more useful, without causing significant harm to primary stability.
2-cylindro-conical or (anatomical) or (radicular) screw implant: these implants have a diameter that decreases from the neck to the apex. Their shape, which is similar to that of a natural root, is particularly interesting in cases of extraction followed by immediate implantation or in the presence of vestibular concavity, radicular convergence or anatomical obstacle (maxillary sinus, mental foramen, mandibular canal). The diameter of the implant body decreases in the coronal-apical direction.
This shape requires the use of specific surgical drills to give a conical shape to the bone site.
The advantage of this implant is that the conical volume fits more easily into a concave crest or between two converging roots. This shape therefore broadens the scope of indications for standard implant treatment.
In these cases where the apical bone volume is restricted, the use of such implants often allows the placement of short implants or the use of bone volume techniques without compromising aesthetic and prosthetic requirements.
3-Stepped implant: it is presented in the form of a succession of conical parts of decreasing diameters. This form is still currently retained because it allows adaptation to certain immediate extraction-implantation situations. The form is closer to that of a dental root. It constitutes an intermediate stage between the cylindrical form and the conical form.
The different types of implants and materials
Cylindrical body of the implant Conical implant Stepped implant
External collar internal collar
b-The coils : the coils constitute an important part of the implant body, they generally extend at the apex according to an identical or different screw thread. They participate in the primary stability of the implant obtained by the pressure exerted between them and the bone.
Their shape dictates the self-tapping or non-tapping insertion mode . Those that have undergone sandblasting during their surface treatment become rounded and lose their cutting edges.
c-screw pitch : at the implant level, the screw pitch varies between 0.6 and 1.25 mm. At the micro-thread of the neck it is 0.2 or 0.3 mm. The smaller the screw pitch, the longer the time required to screw the implant.
The different types of implants and materials
Geometry of the coils Width of the screw thread
Symmetrical turns Asymmetrical turns 0.6mm 0.8mm
d-apex : this part of the implant can be either active (secant) or passive (rounded).
1-rounded apex : the geometry of the apex is rounded. Its lack of aggressiveness does not allow progression in the implant pocket at the end of the stroke.
It is often associated with its non-self-tapping character.
A rounded apex is particularly indicated when the apical part of the implant is brought into contact with a fragile structure such as the sinus membrane.
2-working apex : the working apex is secant. It generates the screw thread and allows the implant housing to be tapped when placing the implant. If the lodge is too small to receive the implant, it is still possible to progress apically until it is fully seated.
e-Diameter: the classification of implants is done according to three diameter classes:
-Small less than 3.5mm
-Standard from 3.75 to 4.5 mm
-Larger than 4.5mm
- Standard diameter implant: This is the implant diameter used since the 1980s. It is the reference diameter that can be used in most clinical situations. (3.75 3.8 4.0 4.1 4.5)
- Small diameter implant: this is an implant that has less mechanical resistance. It should therefore only be used in specific situations.
-a reduced interdental bone space
-a thin alveolar ridge
-a limited cervical prosthetic diameter
It is contraindicated if the mechanical stress is significant.
This implant, compared to the standard diameter implant of the same shape and length, has less primary stability, which makes its use difficult in low-density bone. In practice, the characteristics of these implants limit them to replacing mandibular and maxillary lateral incisors. (3.25 3.3 3.5)
- Large diameter implant: this type of implant has three major advantages:
-an increase in the prosthetic seating surface by increasing the diameter of the neck
-an increase in mechanical resistance by increasing the overall diameter of the implant.
-an increase in the bone/implant interface and therefore in primary stability.
This implant then responds to certain specific situations:
-insufficient bone quality
-insufficient crestal height
-tooth loss of molars
-unitary edentulism
-immediate implantation after extraction
-immediate implantation of an implant.
Indication: This type of implant is mainly indicated for molar replacement when the crestal volume and prosthetic space allow it.(5 6 7)
- implant neck
1-transgingival implant : the concept of the single-part implant comes from the Swiss school, it is also called monobloc and has the particularity of having a long neck which does not stop at the level of the bone crest but which extends through the gum.
The prosthetic pillar is then much shorter and the junction between this pillar and the implant is made in a supracerstal position.
In a two-part system, the prosthetic abutment can be selected and modified after implant placement. The transgingival system allows for simplification of the prosthetic steps but does not provide this flexibility. For these different reasons, it is rather indicated at the level of the posterior sectors.
2-Flared neck implant : The flared neck implant, like the transgingival implant, has a neck and apex identical to those of the standard implant. Only the neck differs in its flare, which makes it possible to obtain:
-a wider prosthetic base, meeting prosthetic requirements in the presence of thin crests, bony concavities or root proximity
-better primary stability, which is indicated in low density bone or in cases of immediate loading
-a wider cortical anchorage, facilitating immediate implantation after extraction. The wide neck closes the extraction site and allows peripheral bone anchorage.
-an improvement in mechanical properties by increasing the contact surface between the prosthetic abutment and the implant neck. This reduces the risks of unscrewing and fractures of screws or implants.
3-straight collar : the height of the collar varies between 0.75 to 1.5mm depending on the manufacturer. The diameters of the collar and the base of the prosthetic abutment do not differ.
4-wide XP type collar : this XP shape (for extra large Platform) is the first variant compared to the straight collar. The widening of the collar leads to the widening of the diameter of the prosthetic base compared to that of the implant body. This shape meets the prosthetic requirements of wide teeth. However, they allow implantation in a site that is not compatible with the insertion of a large diameter implant, for example a molar site in the presence of a thin crest or a bony site with concavities or near a root.
5-neck incorporating Platform-switching : another more recent variant of the widened neck implant presents a widening of the implant neck without changing the diameter of the prosthetic base in relation to the implant diameter. The implant therefore simply presents a bulge at the level of its neck. 6-neck presenting micro-spires : instead of being flat, the neck presents micro-spires. Their external diameter and their screw pitch vary according to the manufacturers. They seem to participate in a better retention of the crestal bone and the latter remains closer to the crestal level of the placement.
The different types of implants and materials
Flared collar straight collar
B-Morphology of the implant connection
The connection system depends on the morphology of the implant neck . It must ensure the anti-rotation properties necessary for the production of a single prosthesis or the placement of an angled stump.
The connection is called external or internal: hexagon: external hexagon, internal hexagon, internal connection of various geometric shapes such as fluted triangle, octagon or Morse cone ensure the stabilization of the different prosthetic parts whose fixation is achieved by screwing thanks to an internal thread present on all implants.
The elements that will be connected to the implants can be either screwed or transscrewed.
All two-stage implant systems use a machined connection type. This is a snap fit between a male and female part that connects the prosthetic abutment to the endosseous implant body.
NB : when the female part is located at the level of the prosthetic pillar, the connection is said to be external. When it is located at the level of the implant, the connection is said to be internal.
When the interlocking allows precise positioning of the prosthetic abutment and prevents any rotation of the abutment in the implant, the connection is said to be anti-rotational.
If the junction does not provide precise indexing of the angular positioning of the pillar, it is then referred to as a non-anti-rotational junction.
The durability of the junction is ensured by a screwing system, generally independent of the implant or the abutment.
Connection type:
There are different types of implant connections that allow the intermediate abutment to be connected to the implant body.
1-External hexagonal connection : This is the oldest since it was already present on the first Branemark implants: it is a plate surmounted in its center by a hexagon, associated with a central screw thread. The abutment is fitted onto the hexagon and screwed using a gold or titanium screw. An X-ray is necessary to check the adaptation of the different elements.
2-internal connection : various types exist
Internal polygon: if initially this system seemed to cause a weakening of the implant neck, modifications of the alloy used and an improvement of the mechanical properties have stabilized it. This system is easier to handle, the control X-rays of the adaptation of the different parts are not obligatory.
a -Morse taper:
- Pure Morse taper : this is a very robust assembly but does not provide a positioning reference for the abutment. It is associated with a specific management of impressions and a slightly different prosthetic logic. In fact, the abutments cannot be modified in the prosthesis laboratory and then repositioned in the mouth because their position varies depending on the tightening torque.
- Anti-rotation modified Morse taper : to solve the positioning problem, an intermediate system combining Morse taper and polygon for positioning identification has appeared. It allows precise identification of the positioning of the abutment on the implant . Communication with the prosthesis laboratory is facilitated. The abutments can be prepared in the laboratory.
b -internal hexagon: the internal connection has an internal hexagon shape. This type is simpler than the external hexagon and facilitates prosthetic manipulation.
c – internal polygon: an audible and tactile click can be added to better understand the correct and complete seating of the prosthetic part.
d – various forms: always in accordance with the principle of internal connection, other forms have emerged in order to try to stand out for commercial purposes. They do not present any proven advantages.
The different types of materials
Implants are usually made of pure titanium or titanium alloy.
The different types of implants and materials
Bibliography:
– Patrick MISSIKA, Anne BENHAMOU, Isabelle KLEINFINGER Access to implantology collection JPIO edition Cdp
-Ashook Sethi, Thomas Kaus clinical implantology diagnostics, surgery and restorative techniques for aesthetic and functional harmony Quintessence international
–MITHRIDADE DAVARPANAH, BORIS JAKUBOXCZ-KOHEN,MIHAELA CARAMAN, MYRIAM KEBIR-QUELIN Implants in dentistry Cdp edition
-M. DAVARPANAH, S.SZMUKLER-MONCLER, PMKHOURY, B. JAKUBOWICZ-KOHEN, H. MARTINEZ. Manual of clinical implantology Concept, protocols and recent innovation 2nd edition
The different types of implants and materials
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