I Osteointegration:
Osseointegration has allowed dental implants to achieve a long-term success rate of 95 percent. This method, developed by Branmark et al. in 1969, is based on six general principles, the first three concerning the implant itself (materials, shape, surface condition), the other three are the way it is used by the surgeon (bone milling, aseptic conditions, loading time). Long-term maintenance of osseointegration depends on the design of the prosthesis and especially on the occlusion.
I.1) Definition of osteointegration:
It is the direct anatomical and functional junction between the remodeled living bone and the loaded implant surface.
I.2) the peri-implant bone response:
Bone has a high potential for regeneration around the implant, after the placement of an implant, a zone of necrosis of approximately 1mm always appears around the implant.
The first step:
This is a healing stage and the replacement of non-living peri-implant tissue by immature bone, of the trabecular type. It is therefore not very resistant to mastication forces.
The second step:
Reworking of this bone, the spaces between the immature bone networks will be covered with mature bone (lamellar), the majority of the bone/implant space will thus be filled with bone tissue. A non-bone surface will remain in contact with the implant which will require a period of approximately 18 weeks to be filled with compact bone.
I.3) factors determining osteointegration:
I.3.1) strict operative asepsis:
Non-contamination of the implant, because if the oxide layer of the implant is contaminated, cell adhesion is compromised.
I.3.2) Primary stability:
This is a crucial factor in achieving osseointegration, stability is largely achieved at the marginal and apical parts of the implant, engaged in the bone cortices. The cancellous bone must have a high proportion of trabeculae to contribute to the support of the implant. A primary anchorage greater than or equal to 25Ncm should ideally be achieved. The initial biomechanical stability prevents micromovements of the implant.
I.3.3) atraumatic surgery:
- Temperature control:
If the surgery is traumatic, the released proteins cannot withstand the increase in temperature and are destroyed. Clinically, if the temperature is higher than 47°C for one minute, it is classically considered that healing may be compromised. To meet these strict conditions, boring instruments of increasing diameter, blank and sterile, are used at speeds lower than 2000 rpm.
- Implant insertion forces:
Excessive insertion forces can induce peri-implant bone resorption. Careful implant placement to ensure good stability is therefore recommended.
I.3.4) Biocompatibility of implant materials:
Pure Titanium, Nobium and Tantalum are materials known for their biocompatibility which is probably linked to the oxide layer which covers them. The latter is very adherent, very stable in the body environment. It has excellent resistance to corrosion.
Commercially pure titanium is the most documented biomaterial in oral implantology, microscopic observations have shown that the titanium/bone interface is devoid of fibrous tissue.
Osteointegration
I.3.5) The shape of the implant:
The functionality of screw implants, without complications, has been demonstrated. Indeed, the presence of screw threads increases the contact surface between the implant and the bone, improves initial stability, resistance to shear forces and the distribution of forces in the bone tissue.
I.3.6) Implant surface condition:
The microporosities obtained after implant surface treatment allow adequate cellular adhesion and consequently an increase in anchoring.
I.3.7) host-related factors:
Patient’s health status, lifestyle habits (tobacco, alcohol), quality and quantity of soft tissues and hard tissues.
I.3.8) bone quantity and quality:
The bone response around an implant is different depending on the type of bone involved, there are several classifications of bone quality and quantity.
- Classification according to bone quality:
The most used being that proposed by Lekholm in 1985, 4 types of bones:
- Type 1: Dense, the clinician does not feel the sensitive delimitation between the cortical part and the spongy part
- Type II: Normal, the clinician clearly feels the transition from the cortex to a less resistant bone
- Type III: Low density, the cortex and the spongy part offer little resistance, they are easily passed.
- Classification according to the quantity of bone:
The classification of Cawood and Howell 1988 is based on the available bone height and includes 6 stages or classes.
- class I: toothed arch
- Class II: bone height after avulsion
- Class III: rounded crest of normal height and thickness
- Class IV: very thin ridges of normal height
- Class V: very resorbed flat ridge
- class VI: negative ridge with basal bone resorption.
I.4) Evaluation of osteointegration:
I.4.1) the Torque:
This value is given when the implant is placed, using a torque wrench; it reflects the primary stability of the implant at a given time. But this mechanical stability, reduced over time, is replaced by biological stability.
Torque therefore does not allow us to assess the evolution of stability over time because this measurement is not reproducible.
I.4.2) Analysis of the resonance frequency:
A part adapted to the connection of the implant or the abutment is screwed . The probe in contact with this part will transfer a frequency which itself has a resonance and will give a value measured by the probe in return. The resonance frequency is directly correlated to the deflection rigidity of the interface between the bone and the implant. When the connection part moves, it will transmit the result of the movement of the implant relative to the bone.
The greater the osseointegration, the less deflection there is and the higher the stability quotient of the implant will be.
Unlike insertion torque, ISQ measurements can be performed multiple times during treatment.
Osteointegration
I.5) Implant success criteria:
Implant success refers to an implant that fulfills its function for many years, meeting functional, psychological and physiological criteria, the most used success criteria are those of Albrektsson and AL:
- Clinics: Immobility of the implant, clear sound on percussion, absence of infectious syndrome, absence of permanent paresthesias
- Radiological: Absence of peri-implant radiolucent image, vertical bone loss less than 0.2mm per year after the first year of implant operation.
II. Mucointegration:
The term “peri-implant mucosa” refers to the soft tissues surrounding the implant.
Secondarily to the closure of the mucoperiosteal flap following implant placement, healing of the soft tissues results in the formation of a peri-implant attachment. This mucosa constitutes a waterproof sleeve that protects the peri-implant bone from the oral environment, thus preserving osseointegration.
The presence of keratinized gingiva is a success factor because it improves the prognosis, and brings advantages: It improves aesthetic integration, conditions the emergence profile; masks the implant-prosthesis connection, acts as a barrier against inflammation, improves the maintenance and stability of the marginal gingiva, resists mechanical aggression, facilitates plaque control and maintenance. The absence of keratinized peri-implant mucosa therefore increases the susceptibility to plaque-induced tissue destruction.
Dental crowns are used to restore the shape and function of a damaged tooth.
Bruxism, or teeth grinding, can cause premature wear and often requires wearing a retainer at night.
Dental abscesses are painful infections that require prompt treatment to avoid complications. Gum grafting is a surgical procedure that can treat gum recession. Dentists use composite materials for fillings because they match the natural color of the teeth.
A diet high in sugar increases the risk of developing tooth decay.
Pediatric dental care is essential to establish good hygiene habits from an early age.