When patients request dental implant treatment or are identified as candidates for implant therapy, they often present with failing teeth that need to be removed or have recently been extracted. Once a tooth has been removed, dynamic physiological and dimensional changes take place during the healing phase that may influence the choice of the best time to place an implant. These dimensional changes are clearly visible in the clinical situation of the site eight weeks after tooth extraction. There are several time points following tooth extraction that may be considered for the placement of dental implants. Each time point has advantages and disadvantages. The clinician is in a unique position to be able to prescribe the time for implant placement following tooth extraction in order to maximize the advantages and to achieve successful long-term outcomes. An understanding of the factors that are important in determining the timing of implant placement is an essential part of the treatment planning process. These factors will be presented in this module.

Once you have completed this ITI Academy module, you should be able to define the different time points for implant placement after tooth extraction and describe the differences between these time points, list the advantages and disadvantages of each time point and list the clinical criteria for selecting the time point most appropriate for the clinical case, as recommended by the ITI.

At the third ITI consensus conference in 2003, it was acknowledged that the terminology routinely used to describe the various time points for implant placement after tooth extraction was imprecise. Terms such as early, delayed and late implant placement were open to interpretation, making it difficult to compare the outcomes from clinical studies. Recommendations for rigid time points were also unhelpful, as great variability can be observed in the healing response when teeth are extracted, as can be seen in these two clinical images. The ITI therefore recommended a classification system that was based on the desired clinical outcome during the post-extraction healing period, rather than on descriptive terminology or fixed time frames. This classification will now be described.

Type 1 implant placement or "immediate implant placement", as it is commonly referred to, is defined as the placement of an implant into a tooth socket immediately following extraction of the tooth. At this time point, the desired clinical outcome is a non-healed extraction socket. The healing time is typically zero days since implantation takes place in the same surgical procedure as the extraction.

Type 2, or "early implant placement with soft tissue healing", refers to the placement of an implant when complete soft tissue coverage over the socket has occurred. At this time point, there is usually limited bone fill within the extraction socket. The desired clinical outcome is therefore substantial soft tissue healing over the socket. On the clinical image taken eight weeks after extraction of the central incisor, most of the soft tissue has healed, except for a small area at the center of the socket which has not completely matured. This image is typical for Type 2 implant placement. As a general observation, the time required for soft tissue healing to take place ranges from four to eight weeks, depending upon the size of the socket and extent of infection present at the time of extraction.

Type 3 describes implant placement following significant bone fill of the socket. At this stage, implant placement is still considered to be at an early time point after tooth extraction. It is referred to descriptively as "early implant placement with partial bone healing". The desired clinical outcome of partial bone healing in the socket is usually determined radiographically. This process can take from twelve to sixteen weeks after extraction, depending upon the morphology of the socket and the extent of apical pathology and bone loss associated with the removed tooth. The clinical image shows the degree of healing at a lower molar site twelve weeks after extraction. The cone beam computed tomography or CBCT image confirms that the bone has partially healed within the extraction socket.

Type 4 is also referred to as late implant placement and is the fourth and final time point for implant placement. It is defined as implant placement into a fully healed site. In most cases, a healing period of six months or longer is required for a socket to be fully healed. The images show a maxillary central incisor site a couple of years after removal of the tooth. The cone beam CT scan confirms that the ridge has fully healed.

Definition of Time Points, Key Learning Points: Implants may be placed at various time points following the removal of the tooth. The classification of the timing of implant placement is based on the desired clinical outcome after healing. These outcomes include a non-healed socket, soft tissue healing, partial bone healing or a completely healed site.

Next, we will focus on each time point for implant placement after tooth extraction and its clinical advantages and disadvantages. It is important to understand these advantages and disadvantages in order to determine the optimal time point to place an implant for a given case.

With Type 1 placement, the extraction of the tooth and the placement of the implant are combined in the same surgical procedure as seen in the clinical images. This time point has several advantages. There is less morbidity for the patient since only one surgical procedure is performed. The overall treatment time is reduced compared to early and late implant placement.

At the time of tooth extraction, the socket walls have not yet undergone resorption. The peri-implant defects usually present as two- or three-wall defects. Implants placed at this time point are positioned within the socket and lie within the envelope of the alveolar bone. The diagram illustrates an occlusal view of an implant placed into a maxillary central incisor site. The implant has been placed palatally and is in contact with the palatal wall of the socket. The proximal and facial bone walls of the socket are intact and together form three bone walls around the implant.

Two- and three-wall peri-implant defects have also been shown to have a favorable defect configuration for simultaneous bone augmentation. This diagram illustrates the occlusal view of an implant placed into a socket that has lost a part of the facial bone wall. In this situation, the proximal bone walls are intact. The peri-implant defect therefore has only two bone walls - a mesial and a distal wall. This defect configuration still remains favorable for simultaneous bone augmentation procedures as the two remaining bone walls are able to contain and protect particulate bone grafts. In addition they provide bone progenitor cells from the marrow spaces.

In selected clinical situations, a provisional crown may be attached to the implant immediately after placement, thereby providing a fixed provisional restoration during the healing phase. This bypasses the need for a removable interim prosthesis and can be an advantage for the patient particularly when replacing maxillary anterior teeth.

Despite these advantages, however, there are significant disadvantages to Type 1 implant placement. The surgical placement is technically demanding as the morphology of the site increases the difficulty of placing the implant into an ideal restorative position. For example, and as shown in the diagram of an implant-supported reconstruction in the anterior maxilla, the implant needs to be placed into the palatal bone wall of the socket to be in the correct orofacial position. The dense bundle bone that lines the socket increases the technical difficulty of preparing the implant site and also increases the risk of the implant deflecting too far towards the facial aspect. Seen here as a red dotted line, the axis of the implant is positioned too far to the facial side compared to the ideal axial position, which is shown as a white line. Such an implant position may lead to soft tissue recession.

The morphology of the socket, particularly of multi-root teeth, may also increase the complexity of implant site preparation. The number of roots, the socket shape and dimensions can make it difficult to achieve initial implant stability, as demonstrated in this diagram.

A significant disadvantage of Type 1 placement is the lack of soft tissue over the extraction site. If grafting material has been placed into the socket around the implant there is usually a need for primary closure to protect the material. Additional procedures need to be performed, such as advancing the facial flap and soft tissue socket sealing techniques. These extra steps increase the complexity of the procedure.

It is not possible to predict the extent of bone modeling and resorption that occurs following Type 1 placement. Horizontal and vertical resorption of the facial crestal bone takes place following tooth removal. The thinner this bone is, the greater the extent of the horizontal and vertical dimensional changes. The consequence of this may be recession of the midfacial peri-implant mucosa.

Even with the placement of an implant and a bone graft into the peri-implant defect, resorption of the facial bone wall will still take place. The images demonstrate the possible consequences of bone modeling and resorption. In the left diagram an implant has been placed into an extraction socket. The facial bone defect has been grafted with a bone substitute that is shown as a grey structure. The right diagram demonstrates a situation where the facial bone has resorbed even in the presence of the bone graft. The facial bone wall has undergone a loss of both height and thickness.

With Type 1 implant placement, the clinician cannot be certain that complete regeneration has taken place within the socket when the implant is prosthetically restored. The only way to verify that bone regeneration has taken place is to perform a surgical re-entry procedure. Most clinicians, however, do not routinely perform a re-entry procedure, as the additional surgical intervention can cause recession of the mucosa. In this clinical example, a re-entry procedure was performed 18 months after Type 1 placement. A lack of bone formation within the original socket and peri-implant defect are clearly visible. The patient developed a peri-implant infection because the exposed part of the implant became contaminated with plaque.

Type 2 implant placement is performed after a healing period of four to eight weeks and has several advantages. The first advantage is that any pathology associated with the extracted tooth has time to resolve. The clinician can be certain that the implant is placed into a site that is free of inflammatory or infective processes. The second and most significant advantage of Type 2 implant placement is that the mucosa heals over the extraction socket with an increase in soft tissue volume. This allows the clinician to achieve tension-free wound closure more easily than with Type 1 placement. Tension-free wound closure is required when simultaneous bone augmentation procedures are performed. In this case, significant inflammation is associated with a maxillary left canine that is undergoing external cervical root resorption. Eight weeks after tooth extraction the inflammation has resolved and the soft tissues have fully healed over the socket. The additional soft tissue volume is a great advantage when placing implants in esthetically critical areas. A thick band of mucosa on the facial aspect of an implant restoration is a prerequisite for successful and stable soft tissue esthetics. A very good esthetic outcome has been achieved in this case.

At this time point of four to eight weeks after tooth extraction, some horizontal resorption of the ridge has occurred and the edges of the bone defects have rounded off slightly as seen in the schematic drawing. However, the peri-implant defects encountered usually still present as two- or three-wall defects and remain favorable for simultaneous bone augmentation procedures.

The slight horizontal resorption causes a flattening of the facial bone contour. This provides space to graft the facial bone surface with bone substitutes that have a low substitution rate and are dimensionally stable over time. This resorption characteristic is regarded as important to maintain healthy bone support and in esthetic areas, to reconstruct and maintain the contour of the ridge.

The clinical case shows an implant that has been placed in a Type 2 procedure and has a residual dehiscence bone defect. A bone substitute has been placed onto the facial aspect of the implant. The material has not only been used to reconstruct bone on the exposed part of the implant surface, but also to recreate the contour of the ridge. This has been achieved by extending the bone substitute over the bone on either side of the implant. Flattening of the ridge facilitates this procedure by providing space for the grafting material. The grafting material should have a low substitution rate so that it remains dimensionally stable over time.

The disadvantage of Type 2 placement is the need for two surgical procedures; the first is performed to extract the tooth and the second to place the implant four to eight weeks later. The extraction, however, can often be done without the elevation of a surgical flap to reduce the overall surgical morbidity for the patient. It should be noted that in multi-rooted sites or teeth with extended apical bone defects, insufficient bone regeneration within the extraction socket may make it difficult to place an implant with primary stability using a Type 2 approach. The radiograph shows an extended apical defect associated with the maxillary right central incisor. With Type 2 placement, there is a high risk that the bone may not heal sufficiently to allow an implant to be placed with adequate stability. In situations like this, extending the healing time to allow Type 3 placement may be more appropriate.

Type 3 implant placement is performed twelve to sixteen weeks after tooth extraction. The main advantage of this approach is that sufficient bone has formed in the extraction socket to allow implant stability to be more readily attained. This is particularly relevant for multi-rooted sockets or for teeth with large apical bone defects. With partial regeneration of bone in the socket, there is a better chance of anchoring the implant with sufficient stability to ensure that the integration process is not disturbed.

This clinical case demonstrates the placement of an implant into a mandibular molar site. At the time of extraction, the mesial and distal root sockets are clearly evident. The site was left to heal for twelve weeks. At surgical re-entry after twelve weeks of healing, the extraction site is almost completely filled with bone. This bone fill allows the implant site to be prepared with adequate surrounding bone walls. The implant has been placed in an ideal position and with sufficient primary stability. A bone graft was not required.

The other advantages of Type 3 placement are similar to the ones for Type 2 placement: Any pathology related to the extraction site has had sufficient time to resolve completely. The fully healed soft tissues allow tension-free wound closure and improved esthetic outcomes. Residual peri-implant defects will still present as two- and three-wall defects in most cases and the flattening of the ridge facilitates the reconstruction of the original ridge contour with the help of bone substitutes.

At this time point, however, further horizontal resorption of the ridge will occur. The extent of the resorption can vary considerably between patients and sites. This case illustrates a maxillary lateral incisor with a large apical defect. Fourteen weeks after extraction, the radiographic examination reveals that bone has begun to grow into the socket. This increases the chances of achieving sufficient implant stability when the implant is inserted. However, the clinical image shows that significant horizontal resorption of the ridge has occurred at this time point. Therefore with Type 3 placement, the increased horizontal resorption at this time point increases the risk that there may not be enough bone volume to allow the implant to be placed in the correct restorative position. It may be necessary to consider a staged augmentation approach, which means a bone augmentation is performed as a first step and is then followed by the placement of the implant several months later as a second step. Although two surgical appointments are usually required for Type 3 placement, this increases to three surgical appointments if a staged augmentation procedure is required. Another disadvantage of Type 3 placement is that the overall treatment time is extended compared to Type 1 and Type 2 placement.

With Type 4 placement, the bone and soft tissues have fully healed, which allows primary implant stability to be readily achieved. The advantages of Type 2 and Type 3 placement are carried through to Type 4 placement. These include resolution of any pathology associated with the extracted tooth, better chances of achieving primary implant stability, and additional soft tissue volume allowing for tension-free wound closure and flap management to enhance esthetic outcomes.

The disadvantages of Type 4 placement, however, are significant. With this extended treatment time, the alveolar bone exhibits the greatest amount of resorption of any of the preceding placement times. There is the greatest risk that this resorption will limit the amount of bone available to place implants. In this clinical case, there was insufficient bone to place an implant in the maxillary left lateral incisor site. A bone graft consisting of an autologous cortical block combined with particulate bovine bone mineral was used to augment the facial volume of the ridge. The graft required six months to mature before a second surgical procedure was performed to place the implant. After six months, the ridge displayed adequate bone volume and an implant was placed in a good three-dimensional prosthodontic position. Type 4 placement therefore has the highest risk of requiring a staged bone augmentation procedure to prepare the site for implant placement.

Advantages and Disadvantages of Time Points, Key Learning Points: With Type 1 or immediate implant placement, extraction and implant placement are combined in the same surgical procedure. The peri-implant defects will usually present as two-or three-wall defects. Under certain clinical conditions, a provisional crown may be attached immediately to the implant, thereby avoiding the need for a removable interim prosthesis. The disadvantages of Type 1 placement include the socket morphology that may compromise implant position and stability, lack of soft tissue volume to facilitate wound closure and to enhance esthetics and inability to predict the extent of bone modeling and defect fill following the placement of the implant.

For Type 2 placement, the advantages include resolution of pathology, an increase in soft tissue volume, favorable peri-implant defect morphology with two- and three-wall defects, and flattening of the ridge which allows grafting of the external surface of the ridge for contour augmentation. The disadvantages of Type 2 placement are that two surgical procedures are required, and that residual defects in the bone may not allow the implant to be placed with sufficient primary stability.

With Type 3 placement, partial healing of the bone within the socket allows implant stability to be more readily achieved. All the advantages of Type 2 placement including the resolution of pathological processes, increased soft tissue volume, favorable peri-implant defect morphology and flattening of the ridge are present. The main disadvantage of Type 3 placement is that the increased horizontal resorption seen at this time point can reduce the bone volume to an extent that an implant cannot be placed in the correct restorative position. This may necessitate staged bone augmentation prior to the placement of the implant. Treatment time is extended, compared to Type 1 and Type 2 placement.

The alveolar ridge is completely healed when Type 4 placement is undertaken. The healed bone allows implant stability to be readily achieved. All the advantages of Type 3 placement are present. The disadvantages, however, are mainly a result of the extensive resorption of the ridge that can occur at this time point. Another disadvantage is the overall treatment time, which is the longest of the four types.

In the following you will learn about the clinical guidelines recommended by the ITI to achieve predictable outcomes with implant placement after tooth extraction. To ensure optimal results and to reduce the risk of complications with implant placement post-extraction, as a general principle a proper risk assessment of the patient and the site need to be undertaken as a first step. In areas of esthetic importance, an Esthetic Risk Assessment should also be undertaken as part of the diagnostic process.

Type 1 or immediate implant placement may be considered when the following clinical conditions are met: Sites with a low esthetic risk profile. This includes posterior teeth, or anterior teeth in patients with a low lip line. It is preferable that the site has a thick gingiva. Thick soft tissues are more robust and less likely to recede following surgical manipulation. The site should also have thick facial bone walls, as can be seen in this clinical image. Evaluating the thickness of the facial bone can be difficult and may require adjunctive diagnostic information including cone beam computed tomography imaging. Extraction sites with thick facial bone may demonstrate a lower propensity for crestal bone resorption. The sites should also have intact facial bone walls. The condition of the facial bone can be diagnosed clinically. Deep periodontal probing or sinus formation on the facial aspect of the tooth to be extracted generally indicates damage or loss of the facial bone wall of the socket. Sites with pre-existing damage to the facial bone are at a greater risk of soft tissue recession even with adjunctive bone augmentation procedures. To be successful with Type 1 implant placement, the clinician needs to be able to correctly evaluate the risk factors and select the case for treatment.

Type 2 implant placement may be considered in most clinical situations. They include both thin or thick gingiva, thin or thick facial bone walls, intact or damaged facial bone walls as well as the presence of pathologies. Due to the soft tissue healing and the increased volume of mucosa, surgical procedures are facilitated and esthetic outcomes can be achieved more reliably. The only situation in which Type 2 placement may not be appropriate is where primary stability of the implant may be compromised due to the morphology of the healing socket or the presence of extended apical defects which have not healed sufficiently.

Type 3 placement allowing a healing period of eight to twelve weeks is usually recommended when extra time is needed for bone healing to take place within the socket and if there is a concern that implant stability cannot be achieved with a Type 1 or Type 2 approach. The radiographs illustrate two examples where Type 3 placement is indicated. In the image on the left, a maxillary lateral incisor site has an extended apical defect due to a cyst. In the image on the right, a maxillary first molar in the first quadrant has a complicated root morphology. Here an extended healing period will be required to ensure adequate bone regeneration within the socket.

Type 4 or late implant placement is generally not recommended due to the risk of extensive resorption of the ridge post-extraction. If Type 4 placement is considered, a ridge preservation procedure using a slow resorbing bone substitute to fill the fresh extraction socket should be considered. This is an effective way of maintaining the dimensions of the ridge to allow implants to be placed at a later time. The clinical image demonstrates grafting of the extraction socket with a bovine bone mineral in a patient who is too young to receive an implant. The aim is to maintain the dimensions of the ridge so that an implant can be placed a few years later when the patient is older.

Clinical Criteria for Case Selection, Key Learning Points: Specific clinical conditions should be present when selecting Type 1 implant placement after tooth extraction. The site should have low esthetic risk and the gingival tissues should be thick. The facial bone should also be thick and undamaged. Under these conditions, Type 1 placement can be performed with a low risk of complications. In contrast, Type 2 placement can be considered in most clinical situations. No specific clinical criteria are required other than achieving primary stability when the implant is placed. In situations where primary stability cannot be achieved with certainty, a Type 3 approach should be considered. Type 4 placement is not recommended as a routine treatment approach, as the disadvantages associated with resorption of the ridge outweigh the clinical advantages.

Module "Timing of Implant Placement after Tooth Extraction", summary: Implants can be placed at any time point after tooth extraction. Each time point has specific clinical advantages and disadvantages that should be carefully considered. The clinician should select the time point that provides optimal outcomes with minimum risk.