TRANSITIONAL PROSTHESIS AND IMPLANT PROSTHESIS (General)
I- Terminology
1 Temporary prosthesis
The temporary prosthesis is a new or old modified prosthesis worn during the periods of osseointegration or development of the definitive prosthesis.
Temporary prostheses are never well adapted. Their inadequacies do not allow in any way the adaptation to the future wearing of a worn implant prosthesis.
This means that this type of prosthesis does not use implants as a pillar allowing prosthetic stabilization during the bone healing phases. Its essential role lies mainly in compensating for edentulism by rehabilitating the masticatory system without using the implant system.
In these cases, it is then a question of:
• removable prostheses whose intrados is fitted with delayed-setting resins.
• standard prostheses or new prostheses, fixed (tooth-supported), but adapted to the consequences of implant placement, in this sense an arrangement will be made at the peri-implant area (clearing of the intrados of the pontics for example).
2 Transitional prosthesis
A transitional prosthesis is a “prosthesis worn after or in place of a temporary prosthesis and whose design is specially adapted to learning access to cleaning, aesthetics and bone remodeling after osseointegration”.
The design of this type of prosthesis (shapes, dimensions, anchoring methods, etc.) is close to the final prosthesis. It is this which will allow the final changes to be made to the final prosthesis by validating:
– shape, shade and position of the teeth as well as the occlusion
– hygiene maintenance control and modification to facilitate access to cleaning
– phonetics control
– maintenance of osteointegration: role in the formation and reorganization of mature bone promoted by more progressive functional stress on the support tissue
3 Waiting prosthesis
It is a prosthesis designed like the definitive prosthesis but with fewer or narrower extension teeth and which is worn during the bone remodeling period after osseointegration.
It is a prosthesis substantially identical to the definitive prosthesis but where the functional loads are reduced. They are put in place in cases of progressive loading when the implants or bone foundations are not worthy of trust.
absolute.
II- The different temporization prostheses used in implantology
The transitional prosthesis allows for progressive muscular and articular, aesthetic, phonetic and psychological conditioning of the patient and provides us with all the requirements necessary for the creation of the definitive prosthesis.
We will consider the different timing possibilities:
Removable temporary prosthesis,
Fixed temporary tooth-supported prosthesis,
Fixed implant-supported temporary prosthesis
1 REMOVABLE TEMPORIZATION PROSTHESES
Indications
The temporary removable prosthesis is the simplest solution technically because it adapts to all clinical situations:
– single tooth loss
– complete edentulism
– partial posterior edentulism
– partial recessed tooth loss of small or large extent (greater than 5 teeth).
It will be developed very quickly after the extractions or better before, according to the principle of the post-extraction prosthesis so that the patient remains edentulous for as little time as possible. We can also consider using the patient’s usual prosthesis. He will accept the transitional phase more easily.
Metal frame prostheses can only be kept if the alterations to the intrados allow for a sufficiently large spacing and do not weaken the prosthesis.
If the prosthesis fractures, it will transmit iatrogenic forces that are detrimental to osseointegration.
Benefits
• It adapts to all clinical situations
• Its speed of execution allows the practitioner to put it in place immediately after the extractions. It will have been carried out previously, according to the principles of immediate prosthesis
• In resin, it represents a reduced financial cost
• It does not require preparation of existing residual teeth
• It allows easy oral hygiene.
TRANSITIONAL PROSTHESIS AND IMPLANT PROSTHESIS (General)
Disadvantages
• The removable character
. Modifications must be made to the intrados of the temporary prosthesis in relation to the implants in order to avoid any mechanical stress.
2 DENTO-BEARED TEMPORIZATION PROSTHESES
A very large number of patients wish to have a fixed temporary prosthesis while waiting for an implant-supported bridge. Depending on the tooth loss to be restored, the use of the fixed temporary prosthesis will be more or less easy and will sometimes involve a modification of the treatment plan with a significant extension of its duration.
3 IMPLANT-BEARED TEMPORIZATION PROSTHESES
The implant-supported temporization prosthesis allows the management of the pre-implant period and the osseointegration period,
Immediate loading processes eliminate the waiting period: the implants are fully functional from the day of placement. The prosthesis that covers them is only an exact copy of the final prosthesis.
3.1 Immediate temporization prostheses
The purpose of this type of restoration will be to restore an aesthetic function and will have no functional purpose.
Conditions of implementation
– The implant must have excellent primary stability on the day of placement.
– The occlusal anatomy of the temporary prostheses will be free from any contact with other antagonistic occlusal reliefs.
Benefits
• Patients leave the surgical procedure with a temporary prosthesis that allows for optimal aesthetic restoration.
• Soft tissue healing is guided by the transitional prosthesis for better final prosthetic integration.
Disadvantages
This type of temporary restoration is only possible when there is no functional contact. The patient should then be warned not to interpose the prosthesis during masticatory functions in particular.
Immediate charging
Immediate loading involves placing the prosthetic part and putting it into function immediately after implant placement. The prosthetic element will be either a transitional prosthesis or the definitive prosthesis.
The principle of immediate loading violates two fundamental rules of the implant approach according to Brânemark PI:
• Covering of implants by the mucosa during their placement.
• The implants become functional after a healing period of 3 to 6 months.
III- Implant prostheses
A. Transscrewed implant-supported prosthesis
This type of prosthesis is defined as a restoration screwed either directly onto the implants or onto intermediate elements (abutments) themselves screwed onto the implants.
The fixed transscrew prosthesis can be made by a one- or two-stage restoration depending on the clinical case and the choice of the implant system. An abutment with an anti-rotational device is essential for the creation of a single-unit restoration. An abutment without an anti-rotational device can be used for the creation of a multiple-unit restoration.
TRANSITIONAL PROSTHESIS AND IMPLANT PROSTHESIS (General)
a- Advantages
This prosthesis has several advantages:
Removal is made easier if necessary (screw change, abutment mobility);
Clinical hindsight is significant (numerous publications)
The gold screw in the prosthesis may signal a biomechanical problem
In fact, its unscrewing alerts you to a prosthetic complication (occlusal problem, functional overload);
The absence of sealing cement during the placement of the prosthesis prevents any risk of peri-implant aggression (fusion of cement under the mucosa).
b) Disadvantages
- Surgical
The position of the access shaft often limits the surgeon’s field of action (incompatibility of the two surgical and prosthetic axes) depending on the available bone volume .
- Aesthetics
The occlusal anatomy is altered by the presence of screw access holes.
The anatomical emergence profile is sometimes difficult to achieve.
In the anterior maxillary sector, the inclination of the alveolar crest can cause the screw to emerge on the vestibular surface
- Functional
The occlusal morphology is altered. The difficulty of occlusal adjustment is more or less important depending on the size of the access well.
- Biomechanics
There is a high risk of unscrewing for the prosthesis screw. Indeed, it is tightened to 10 Ncm.
The risk of fracture of the ceramic is greater than for a non-screwed prosthesis, this is due to the ceramic/composite junction.
- Techniques
Is difficult to achieve with a large number of implants.
Production difficulties arise in the presence of limited prosthetic space (only direct restoration on implants is then possible).
The temporary prosthesis is difficult to make
c. Devices of transscrewed prostheses
Two main types of transscrewed prostheses are distinguished;
A- the single-stage prosthesis , whose cervical limit rests on the implant and not on the “internal” abutment. This is a “monobloc” prosthetic restoration directly transscrewed onto the implants and usable in anterior aesthetic cases and in posterior cases with small prosthetic space . It requires that the emergence orifice of the screw be located in the center of the occlusal surface.
Indications for this technique
– Single or multiple restoration;
– Anterior and posterior restoration;
– Aesthetic restoration with thin gums;
– Soft tissue thickness less than 2mm (gingival height);
– Low inter-arch prosthetic space (minimum possible 4mm);
– Access well to the occlusal screw (transscrewing possible).
B – the two-stage prosthesis , the cervical limit of which rests on the intermediate pillar and not on the implant.
This is a solution in which the crown and its cervical limit rest entirely on the abutment and not on the implant. This technique can be used in anterior and posterior cases when the prosthetic space is sufficient and the height and thickness of the soft tissues are significant. It requires that the access well be occlusal.
Indications for transgingival abutments:
– Single or multiple restorations;
– Anterior or posterior restorations
– Cosmetic restorations
– Low prosthetic space (minimum possible: 6mm);
– Soft tissue height greater than or equal to 2mm (gingival height);
– Correction of convergent or divergent implant axes
Limit of transgingival abutments:
– Screw thread orifice too vestibular or lingual (visibility, weakening of the ceramic);
– Implant axes with convergence or divergence greater than 35°;
– Gingival height less than 2mm;
– Interarch space less than 6.5mm.
TRANSITIONAL PROSTHESIS AND IMPLANT PROSTHESIS (General)
B. Sealed implant-supported prosthesis
The sealed prosthesis is defined as a restoration sealed on intermediate elements (abutments) transscrewed on the implants . The sealed prosthesis can be made by a one- or two-stage restoration depending on the clinical case and the choice of the implant system.
The single-stage sealed prosthesis is composed of :
-a standard internal conical titanium abutment, straight or angled, which is screwed or transscrewed;
-a crown with a metal or ceramic frame frame , the peripheral limit of which
fits perfectly to the implant. The crown is retained by sealing.
The two-stage sealed prosthesis includes:
– a transgingival titanium prosthetic abutment screwed or transscrewed onto the implant;
– a crown with a metal or ceramic framework, the peripheral limit of which fits perfectly to the shoulder of the implant abutment. The crown is retained by sealing.
a) Advantages
This prosthesis has many advantages:
– The absence of access wells for the abutment screws allows the surfaces of the crowns to be
identical to conventional ones. This offers a double advantage, namely:
– an improvement in aesthetics mainly at the level of the occlusal surfaces of the mandibular teeth;
– a possibility of balancing and occlusal adjustment identical to that of the fixed prosthesis.
– The necessary spacing for the bonding material facilitates passive adaptation of the reinforcement
– The aesthetic result can be optimized by adapting the emergence profile;
– Removal is made easier if necessary (sealing with temporary cement);
– Clinical hindsight is significant (numerous publications).
b) Disadvantages
The disadvantages are significantly fewer than those of the transscrewed prosthesis.
– The sealing cement, during crown placement, may cause irritation of the peri-implant mucosa in the event of fusion or incomplete elimination in the soft tissues.
-In case of unscrewing of the abutment screw, it is sometimes necessary to cut the crown despite the use of a temporary sealing cement;
-Maintenance and disassembly of prostheses are difficult to perform.