Immediate Implant Placement : Current Concepts

Immediate implants following extraction has become an increasingly popular strategy to preserve bone and reduce treatment duration. This technique also improves aesthetics by preserving the soft tissues. Immediate implant placement is technically challenging and should only be undertaken by clinicians with considerable experience in implant dentistry, both surgically and prosthetically. The purpose of this article is to provide a general review about immediate implant placements and to summarise various aspects in which this technique can


INTRODUCTION
Replacement of missing teeth using dental implants has proven to be a popular, successful and predictable treatment procedure.Over the years, different implant placement protocols have evolved in order to achieve easier and quicker surgical techniques.Immediate placement of a dental implant in an extraction socket was initially described more than 30 years ago by Schulte and Heimke in 1976. 1 Lazzara 2 later in 1989 reintroduced the method of immediate implant placement into fresh extraction sockets with three case reports.
Since then, the percentage of partially edentulous patients in implant dentistry has significantly increased.Today, the immediate implant placements predominate in regular dental practice, particularly the single missing tooth 3,4 as the healing period of about six months post extraction prior to implant placement is not an attractive option any more to According to both the osseous and soft tissue levels of the potential site at the time of extraction, Garber classified into: The four treatment options for post-extraction implant placement as defined by the International Team for immediately following extraction of a tooth which must be combined in most patients with a bone grafting technique to eliminate peri-implant bone defects. 10 abundance of literature supports the placement of immediate implants and almost all studies report high survival rates of immediate implants from 92-100% however case selection is necessary. 11

POST-EXTRACTION RIDGE RESORPTION
Dimensional changes of hard tissue 12 1.The inflammatory phase: It starts with the formation of the blood clot.Inflammatory cells migrate to the site to "clean" it before the formation of a new tissue in 2 to 3 days.After 4 to 5 days inflammatory cells, vascular sprouts and immature fibroblasts form a granulation tissue which is gradually replaced with provisional connective tissue matrix that is rich in collagen fibers and cells.

The proliferative phase:
There is an appearance of osteoid calcification, which begins at the base and at the periphery of the socket.The bone matrix appears

Dimensional changes of soft tissue
Immediate implant placement may cause mild gingival recession 16,17 and regardless of the periodontal biotype, a soft tissue defect (in width) is noted.Marginal tissue recession is more evident on implants which are positioned bucally and on gingiva with thin biotype. 18Immediate implants placed along with connective tissue grafts have shown less than 1 mm of marginal tissue discrepancy. 19wever, a recent systematic review by Lee et al, have not found any significant advantage of using connective tissue grafts towards reducing gingival recession. 20Hence, more studies are required to advocate the combined use of soft tissue grafts and immediate implants.ADVANTAGES 24,25 • Reduction in the number of surgical interventions  with regards to soft and hard tissues be followed. 32acement of a wide diameter or a wide platform implants should be avoided in the aesthetic zone sites.Usually, maxillary central incisors, cuspids, and premolars and also mandibular cuspids and premolars are treated with implants having a diameter of approximately four mm.
Implants in the region of lateral incisors and mandibular incisors should not to exceed a diameter of 3.5 mm. 33e clinical guidelines for immediate implant placement protocol are summarised in Table 1.

IMMEDIATE IMPLANTS IN THE POSTERIOR REGION
In the posterior region, implant placement in the root socket can lead to a non-ideal restorative position.This may result in mechanical overload and failure of the implant.In addition, the resulting structure of the restoration may render oral hygiene more difficult, which enhances the risk for periimplantitis.To avoid these potential problems, studies 29 have suggested placing the implant into the inter-radicular bone and augmenting the remaining socket with graft material and a membrane.Although there is limited data on the the long-term performance in published literature, 29,34 the use of immediate molar implants appears to be a valid treatment in the hands of skilled clinicians.Given the complexity of the procedure, clinicians should follow strict guidelines to minimise the risk of complications/failures.
Based on the current literature, the following guidelines are recommended for the implant placement in the posterior region (Table 2): 34

SOCKET PRESERVATION
Most extractions are done with no regard for maintaining the alveolar ridge.Whether due to caries, trauma or advanced periodontal disease, tooth extraction and subsequent healing of the socket commonly result in osseous deformities of the alveolar ridge, including reduced height and reduced width of the residual ridge. 35There is more Joseph and Kitichai reported an alternative approach in a case utilising a retained proximal root fragment to maintain the inter-implant papilla. 37

PROVISIONALISATION
Fabricating provisional restoration allows us to have an idea for definitive crown as similar to the natural tooth that was present earlier.Moreover, it also helps to reform the interdental papilla between the implant supported crown and the natural tooth.Light-cured composite can be used at the base of the provisional restoration to create an emergence profile as it causes less soft tissue irritation.
Elimination of the auto polymerised acrylic resin monomer is responsible for soft tissue irritation with the acrylic resins. 38,39The provisional restoration should be designed so as to minimize pressure on the surgical site, optimize space for the gingival tissues, and control occlusal loading of the implant during the initial stages of osseointegration. 40

JUMPING DISTANCE
The space between the implant periphery and surrounding bone is called the gap or jumping distance. 41The gap consists of two dimensions: Horizontal defect width and vertical The main objective of immediate implant placement is to provide an osseointegrated fixture suitable for an aesthetic and functional restoration.Bone fill in the gap between the implant and the peripheral bone is important.The buccal aspect of an implant is of great concern, especially in the aesthetic zone, because the buccal bony plate is usually thin 42,43 and its resorption can result in soft tissue recession. 44The objective of the surgical management of the buccal gap is optimal bone fill in the gap, most coronal level of bone-to-implant contact and the least amount of buccal bone loss and soft-tissue recession. 45e initial bone wall thickness before the immediate implantation associated with guided bone regeneration may influence bone formation. 46Intrabony defects are partially or completely remodeled (healed) without further intervention. 47A lateral gap of 1 to 1.25 mm could heal spontaneously with formation of a new bone, however the addition of a membrane would not improve the healing process. 47In cases of severe defect, the choice between an immediate implantation associated with guided bone regeneration or a delayed implantation should be evaluated.
The decision criteria for the surgeon are related to the possibility of complete site closure and if not obtained, the risk of membrane exposure may lead to graft complications and implant failure. 48The filling of the gap remained between the implant and the buccal bone plate with autogenous bone graft could be resorbed. 49Bovine hydroxyapatite material could reduce bone resorption in the buccal aspect of the implant. 50Partial bone formation occurs when space is filled by Beta-TCP, however, no scientific evidence of superiority of one material over another has been yet established. 51imal experiments with injection of mesenchymal cells of the umbilical cord in the case of a severe peri-implant bone defect have shown their ability to promote formation of new bone. 52

TECHNIQUES USED IN IMMEDIATE IMPLANT PLACEMENT SURGERY
It is always safe to start with a pilot drill, as there is a risk to slip into the socket and perforate the buccal bone plate because of the hardness of the palatal wall.To avoid this problem, two techniques can be used: 53 1. Round bur technique: The drilling is initiated with a small round bur about 1/3 of the apex on the palatal wall of the socket.The drilling is then carried out keeping a palatal direction with respect to the tooth axis.This technique is indicated in cases of immediate implantation without or with minimal tissue loss (Figure 1).From a biologic point of view, the main advantage of a flapless procedure is preservation of the periosteum and supraperiostal and as a result the blood supply to the alveolar bone is maintained. 57,58Some clinical studies suggest that flapless surgery prevents marginal bone loss.

8 weeks 3 . 16 weeks 4 .
Implantology (ITI) in two ITI Consensus Conferences (2003 and 2008) 9 are: 1. Immediate implant placement: same day of extraction 2. Early implant placement with soft tissue healing:4-Early implant placement with partial bone healing:12-Late implant placement with complete bone healing: >6 months Immediate implant placement may be defined as implant placement immediately following tooth extraction and as a part of the same surgical procedure, or as implant placement

Treatment duration is reduced • 27 •
Bone width and height of the alveolar bone is preserved, enabling maximal utilisation of bone-implant surface area • Ideal orientation of the implant can be achieved • Preservation of bone at the extraction site • Soft tissue aesthetics can be maintained • Better patient acceptance DISADVANTAGES 26,Risk of partial alveolar bone resorption due to a pathologic process or to a traumatic damage during the extraction • Difficulty to achieve a primary stability • Gap between implant surface and socket wall • Additional cost in cases of guided bone regeneration • Difficulty to predict the final position of the implant • Difficulty to achieve a complete closure of the implant site • Need to raise a flap in order to cover the implant if two stage procedures is preferred INDICATIONS 28 substantial horizontal bone loss than vertical bone loss after tooth extraction.The buccal aspect generally displays more resorption than the lingual/ palatal aspect.There is an observed resorption pattern of rapid reduction in the first 3-6 months, followed by gradual reduction thereafter, throughout life.Socket preservation may serve to improve the aesthetic and functional outcomes.Socket preservation techniques are beneficial in preserving alveolar hard and soft tissues.When intact or nearly intact extraction sockets are present, an immediate implant placement technique offers the advantages of the socket preservation technique and reduces the time required to achieve a final restoration.Socket shield technique: In 2010, Hürzeler et al introduced a new method, the socket shield technique, in which a partial root fragment was retained around an immediately placed implant with the aim of avoiding tissue alterations after tooth extraction. 36Histologic evaluation in beagle dogs showed no resorption of the root fragment and new cementum formed on the implant surface.Their clinical case demonstrated excellent buccal tissue preservation and clinically successful osseointegration of the implant.

Table 1 :
Clinical guidelines for aesthetic outcomes.

Table 2 :
Clinical guidelines for immediate implant placement in posterior region.The term "jumping distance" refers to the ability of bone to bridge the horizontal gap and fill the void.
Dhami et al : Immediate Implant Placement: Current Concepts 59,60SUMMARY Immediate implant placement is a reliable technique with implant success rates comparable to those obtained by conventional protocols.It allows a significant comfort to the patient, a reduction of the healing duration and a preservation of the gingival architecture; which optimises the aesthetic outcomes.However proper case selection, diagnosis and treatment planning, clinical expertise, meticulous post-operative care preceded by a good surgical and prosthetic protocol are very essential for the long term success of the immediate implants.