Implants in Postextraction Sites

At the 3rd ITI Consensus Conference in 2003, it was recognized that descriptive terms for the time points for implant placement after tooth extraction encountered in the dental literature were imprecise, and therefore open to interpretation. A classification system for timing of implant placement after tooth extraction was therefore proposed, based on desired clinical outcomes during healing rather than on descriptive terms or rigid time frames following extraction(1).

• Type 1 refers to the placement of an implant into a tooth socket concurrently with the extraction
• Type 2 refers to the placement of an implant after substantial soft tissue healing has taken place, but before any clinically significant bone fill occurs within the socket
• Type 3 is placement of an implant following significant clinical and/or radiographic bone fill of the socket
• Type 4 is placement of the implant into a fully healed site.

In spite of this new classification system, descriptive terms have remained in use since 2003. Therefore, to avoid ambiguity and misinterpretation of the various time points for implant placement after tooth extraction, the descriptive terminology in the ITI Treatment Guide, Volume 3, was adopted for this Consensus Conference(2). The following additional terms were defined:

• Postextraction implant placement: Used to collectively describe type 1, type 2, and type 3 implant placements.
• Early implant placement: Used to collectively describe type 2 and type 3 implant placements.
• Peri-implant defect: The space between the exposed implant surface and the inner surface of the walls of a fresh or healing extraction socket.
• Ridge preservation: A procedure to minimize vertical and horizontal ridge alterations in postextraction sites.

References:(1) Hämmerle CH, Chen ST,Wilson TG Jr.Consensus statements and recommended clinical procedures regarding the placement of implants in extraction sockets. Int J Oral Maxillofac Implants 2004;19(suppl):26–28.

(2) Chen S, Buser D. Implants in post-extraction sites: A literature update. In: Buser D, Belser U, Wismeijer D (eds). ITI Treatment Guide, vol 3: Implants in Extraction Sockets. Berlin: Quintessence, 2008:9–15.

Healing and Regenerative Outcomes

• Modeling of the ridge after extraction continues to occur following implant placement.
• Bone augmentation procedures are effective in promoting bone regeneration with immediate and early implant placement.
• Bone augmentation procedures may compensate for modeling changes and may improve ridge contours.
• Bone augmentation procedures are more successful with immediate and early implant placement than with late placement.

Survival Outcomes

• The survival rates of postextraction implants are high and comparable to those of implants placed in healed sites.

Esthetic Outcomes

• Immediate implant placement is associated with risk of mucosal recession.
• Risk indicators include thin tissue biotype, thin facial bone, dehiscence of the facial bone, and malposition of the implant.
• Based on esthetic indices, 80% of immediate implant sites demonstrate satisfactory outcomes.

Ridge Preservation

• Ridge preservation procedures following tooth extraction result in a greater orofacial dimension of bone than when no ridge preservation procedures are performed.

Advantages and Disadvantages of Immediate Implant Placement (Type 1)

With immediate implant placement (type 1), combining tooth extraction and implant placement reduces the number of surgical procedures that the patient needs to undergo. The peri-implant defect usually presents as a two- or three-walled defect, which is amenable to simultaneous bone augmentation techniques. In addition, there is an opportunity to attach a provisional restoration to the implant soon after placement so that the patient avoids the need for an interim removable prosthesis. However, these advantages are counteracted by the increased technical difficulty of preparing the osteotomy to allow the implant to be placed with initial stability and in a good prosthetic position. There is also an increased risk of mucosal recession, which may compromise soft tissue esthetic outcomes. Additional hard and soft tissue augmentation procedures are usually required to overcome this risk, further increasing the technical demands of the procedure. Although grafting of the peri-implant defect with particulate bone or bone substitutes is readily achieved, grafting of the external surface of the facial bone is more demanding due to the convexity of the bone wall. If primary soft tissue closure is required, the lack of soft tissue increases the difficulty of attaining tension-free closure. Flap advancement may alter the mucogingival line. Clinicians should be mindful of the fact that bone modeling following tooth extraction is unpredictable. This may potentially lead to suboptimal bone regenerative outcomes and unpredictable dimensional changes.

Advantages

• Extraction and implant placement are combined in the same surgical procedure
• Reduced overall treatment time compared to types 2, 3, and 4
• Peri-implant defects often present as two- or three-walled defects, which are favorable for simultaneous bone augmentation procedures

Disadvantages

• Morphology of the site may increase the difficulty of placing an implant in an ideal position
• Morphology of the site may compromise initial implant stability
• Lack of soft tissue volume makes attainment of tension-free primary closure more difficult
• Increased risk of marginal mucosal recession
• Inability to predict bone modeling may compromise outcomes

Advantages and Disadvantages of Early Implant Placement (Type 2)

With early implant placement (type 2), healing of the soft tissues increases the volume of mucosa at the site. This facilitates manipulation of the surgical flaps and allows flap advancement for partial submergence of the implant or primary closure to be more readily achieved. In areas of high esthetic importance, the increased volume of soft tissue may enhance soft tissue esthetic outcomes. In the 4- to 8-week period following tooth extraction, slight flattening of the facial bone wall is commonly observed.This facilitates grafting of the facial surface of the bone with bone substitutes possessing low rates of substitution. These grafts may serve to limit long-term dimensional changes of the ridge. As there is minimal bone regeneration within the socket at this time point, periimplant defects are usually still present. However, the defects usually present with two or three intact walls, which are amenable to simultaneous bone augmentation techniques. The lack of bone regeneration within the socket may increase the difficulty of attaining initial stability of the implant. This approach allows pathology associated with the extracted tooth to resolve prior to implant placement.

Advantages

• Reduced treatment time
• Additional soft tissue volume allows for easier attainment of tension-free closure
• Additional soft tissue volume may enhance soft tissue esthetic outcomes
• Flattening of facial bone contours facilitates grafting of the facial surface of the bone
• Peri-implant defects often present as two- or three-walled defects, which are favorable for simultaneous bone augmentation procedures
• Allows for resolution of pathology associated with the extracted tooth

Disadvantages

• Two surgical procedures are required
• Morphology of the site may compromise initial implant stability

Advantages and Disadvantages of Early Implant Placement (Type 3)

For early implant placement (type 3), partial bone healing in the socket usually allows implant stability to be more readily attained compared to type 1 and type 2 placement. The soft tissues are usually fully healed, allowing tension-free closure of the site. The increased volume of soft tissue may enhance soft tissue esthetic outcomes. However, it should be noted that modeling of the bone is more advanced than with type 2 implant placement. The socket walls exhibit varying degrees of resorption that may limit the volume available for implant placement. Peri-implant defects may still be present, but they are usually reduced in orofacial dimension. Two- and three-walled defects are amenable to simultaneous bone augmentation procedures. Flattening of the facial bone facilitates grafting of the facial surface with bone substitutes, a procedure usually necessary for augmentation of ridge contour. With Type 3 placement, the increased time from tooth extraction allows healing of extended pathological defects to take place.

Advantages

• Partial bone healing usually allows implant stability to be more readily attained
• Additional soft tissue volume allows for easier attainment of tension-free closure
• Additional soft tissue volume may enhance soft tissue-esthetic outcomes
• Peri-implant defects often present as two- or three-walled defects, which are
• Favorable for simultaneous bone augmentation procedures
• Flattening of facial bone contours facilitates grafting of the facial of the bone
• Allows for resolution of pathology associated with the extracted tooth

Disadvantages

• Two surgical procedures are required
• Extended treatment time as compared to type 1 and type 2 placement
• Socket walls exhibit varying amounts of resorption
• Increased horizontal bone resorption may limit the volume of bone for implant placement

Advantages and Disadvantages of Late Implant Placement (Type 4)

In late implant placement (type 4), the socket walls exhibit the greatest amount of resorption. Although the soft tissues are fully healed and manipulation of the surgical flaps is facilitated, ongoing modeling and horizontal resorption increases the risk of there being insufficient bone volume to place the implant. Additionally, there is a greater risk that peri-implant defects will present as no- or one-wall defects, compared to immediate and early implant placement.

Advantages

• Bone healing usually allows implant stability to be readily attained
• Additional soft tissue volume allows for easier attainment of tension-free closure
• Additional soft tissue volume may enhance soft tissue esthetic outcomes
• Allows for resolution of pathology associated with the extracted tooth

Disadvantages

• Two surgical procedures are required
• Extended treatment time compared to type 1, type 2, and type 3 placement
• Socket walls exhibit greatest amounts of resorption
• Greatest chance of increased bone resorption limiting the volume of bone for implant placement

• The clinician has the option of placing implants immediately, early, or late following tooth extraction. The advantages and disadvantages of each approach need to be carefully considered in order to reduce the risk of complications. Therefore, to ensure optimum outcomes, a proper risk assessment of the patient and site should be undertaken. This includes an esthetic risk assessment3 in areas of esthetic importance.
• Whenever implants are placed in postextraction sites, the need for regenerative therapy must always be assessed. Bone augmentation is recommended to compensate for bone modeling, and to optimize functional and esthetic outcomes. In all four placement protocols the ability to attain primary stability in the appropriate restorative position is a requirement. Presence of an acute infection is an absolute contraindication.
• Immediate implant placement (type 1) may be considered in patients and sites with a low esthetic risk profile(1). This includes single-tooth sites with thick tissue biotypes and with thick and intact facial bone walls.
• Early implant placement with soft tissue healing (type 2) may be considered in the majority of sites due to an increased volume of soft tissue available. Early implant placement with partial bone healing (type 3) may be considered if primary stability of the implant in the correct restorative position cannot be achieved with type 2 placement.
• In sites where extensive bone modeling is anticipated, late implant placement (type 4) is the least desirable option. When Type 4 implant placement is indicated, ridge preservation procedures using low-substitution–rate graft materials and membranes are recommended. Such indications include the growing patient, where primary stability cannot be achieved with type 1, 2, or 3 placements due to anatomical restrictions, or when a delay in implant treatment is anticipated.

References:(1) Martin WC, Morton D, Buser D. Diagnostic factors for esthetic risk assessment. In: Buser D, Belser U, Wismeijer D (eds). ITI Treatment Guide, vol 1: Implant Therapy in the Esthetic Zone - Single-Tooth Replacements. Berlin: Quintessence, 2007:11–20.