Implant Placement in Extraction Sockets: A Short Review of the Literature and Presentation of a Series of Three Cases

Dental implant placement traditionally was advocated for healed extraction sites.1 However, with the development of a better understanding of the biologic principles of bone healing around dental implants, placement in fresh extraction sockets has also been tried and reported with a high degree of success,2 and such implants have been described as immediate implants.3 These are different from other similarly named implant procedures, namely, immediately loaded implants and delayed-immediate implants. Immediately loaded implants are provisionalized and/or functionally loaded at the time of placement, while delayed-immediate implants are placed after 6 to 8 weeks of extraction.4 

The following sections present a short review of the literature on immediate implants and a series of 3 cases treated with immediate implants. Some of the important practical points are discussed, and the step-by-step procedure is described.

The discrepancy between the form of a dental implant and the shape of the residual extraction socket is bound to lead to a situation in which there are voids between the implant and the walls of the socket. Histological evidence in animals, including monkeys5,^–9 and dogs,10,^–13 has confirmed that there is adequate bone-implant contact and that osteointegration is achieved in the case of immediate implants. This has also been confirmed by human histology.14 

As highlighted earlier, the presence of marginal voids and a lack of uniform contact between the implant surface and the socket walls are almost imperative with immediate implants. The use of guided bone regeneration for bone formation in critical size defects has been established.15 However, there is conflicting evidence on the use of guided bone regeneration for immediate implants.

A recent study described the healing of marginal gaps of standardized dimensions (width = 1–1.25 mm, height = 5 mm) around dental implants placed in nonextraction sites in dogs.16 Another report from the same group of authors showed that there was only a slight difference in the amount of bone fill with or without a collagenous membrane covering the marginal defect.17 The authors described the retention of the coagulum as being more important than the use of a collagen barrier membrane.

Nevertheless, some studies suggest that the use of bone grafting and barrier membrane at the time of placement of implants in sites with marginal voids may maintain soft tissue contour at a more coronal level by about 1 mm.18 Other authors have highlighted the importance of the width of the residual defect.14 It was noted that a residual defect of up to 1.5 mm wide healed as well as sites without any marginal void but that sites with voids wider than 1.5 mm had almost 50% less bone-to-implant contact.14 A subsequent report described favorable healing and bone-to-implant contact when a barrier membrane was used to cover voids ranging from 1.5 to 4 mm in width.19 It was further highlighted that the osteophilic nature of a grit-blasted and acid-etched implant surface may also have a contributory role in the healing of defects of critical width. Thus, it seems appropriate to graft marginal voids and bony dehiscences, particularly when they are about 2 mm or wider.

Four important factors are to be considered for closure over immediate implants20: (1) position and width of attached gingival, (2) buccal contour/volume of alveolar process, (3) configuration and level of the gingival margin, and (4) shape and size of the interdental papilla.

The following techniques have been reported in the literature to achieve closure over immediate implants: (1) coronally repositioned flap, (2) free gingival graft, (3) subepithelial connective tissue graft, (4) pedicled island flap, (5) pedicled palatal flap, and (6) membranes.

All of these techniques have pros and cons, and it is usually up to the surgeon's discretion to choose any one of them. However, it is not always imperative to completely submerge immediate implants and to have complete soft tissue coverage. Successful and uneventful healing of immediate transmucosal implants has also been reported.21^,22 However, it is extremely important to ensure strict postoperative plaque control.

Most of the available literature on the topic of immediate dental implants consists of case reports and series. There is a lack of long-term clinical trials. However, based on the available evidence, a recent review of the literature concluded that the outcomes of immediate implants, delayed implants, and implants placed in healed sites are comparable.4 

The proposed and perceived advantages of immediate implants include the following:

• reduction in overall treatment duration;

• maintenance of soft tissue profile;

• prevention of the bone loss in both vertical and horizontal directions;

• reduced number of surgeries, thus reducing the overall cost and morbidity;

• a significantly reduced period of wearing of an interim prosthesis that is usually removable and often objectionable to many patients hoping to receive a fixed implant–supported restoration; and

• possible emotionally traumatic loss of anterior teeth. In such cases, immediate implant placement and provisionalization may be a good treatment option.

In the opinion of the authors and based on the review of the literature, the following advantages and shortcomings of immediate implants are evident:

• The ideal modality for the treatment of marginal voids is subject to considerable controversy.

• The additional cost of associated grafting and use of barrier membrane offsets the perceived advantage that the cost is lower due to a lesser number of surgeries.

• More extensive soft tissue manipulation is required if the submerged healing protocol for immediate implants is to be used.

• The procedure may be technically more demanding.

A 50-year-old, medically healthy man was referred by the prosthodontist for implant placement at tooth 45. Clinical examination revealed the presence of root stump of tooth 45 that had been root filled. The tooth was deemed unrestorable because of apical curvature of the root, caries, and poor crown-root ratio (Figure 1). Periapical radiographs showed the presence of a small periapical radiolucency. On comparison with radiographs retrieved from the previous endodontist, it seemed that the size of the lesion was stable over almost 2 years. The periapical radiograph also revealed that the mental foramen was about 3 to 4 mm from the apex of the root (Figure 1).

After a detailed discussion of the procedure, the patient agreed to undergo extraction and immediate implant placement. Two grams of amoxicillin was prescribed to be taken 1 hour before surgery. Local anesthesia was achieved, and a wide-based, full-thickness buccal flap was reflected to identify the mental foramen. The root stump was carefully extracted after luxation with periotomes. The root stump was noted to be about 10 mm long. The socket was carefully modified with appropriate implant drills, and a 3.75-mm wide and 11.5-mm long Branemark implant (Nobel Biocare USA Inc, Yorba Linda, Calif) was placed. Insertion torque was in excess of 30 Ncm. Three threads on the buccal surface of the implant were exposed, and the thickness of the residual buccal crest was noted to be about 1 mm (Figure 2). Marginal voids of about 1.5 mm width were noted between the implant surface and the buccal and lingual cortices. The buccal surface and marginal voids were grafted with bovine anorganic hydroxyapatite (Bio-Oss, Geistlich AG, Wolhusen, Switzerland) and covered with a resorbable collagen barrier membrane (Bio Gide, Geistlich AG), such that the membrane extended at least 3 mm onto healthy bone and covered the occlusal surface completely (Figure 2). The buccal flap was coronally repositioned after horizontal periosteal releasing incision. Primary closure was achieved with interrupted 4/0 vicryl suture. Amoxicillin 500 mg 3 times a day (TDS) was prescribed for 1 week, and chlorhexidine mouthwash was prescribed for 3 weeks.

Subsequent healing was uneventful. Stage 2 surgery to uncover the implant was performed after a period of 4 months. The periapical radiograph showed adequate bone height up to the first thread. During the surgery, all the threads on the buccal surface were found to be covered with bone (Figure 3). The flap was apically repositioned to match the adjacent attached gingival level, and closure was achieved by 4/0 vicryl suture. The patient was then referred back to the prosthodontist, and the implant was restored with a porcelain fused-to-metal crown (Figure 3).

A 35-year-old medically healthy woman was referred by a prosthodontist for extraction of the root stump of tooth 44 and replacement with an implant. The patient was given an explanation of the procedure, and she consented to the immediate placement of implant. The patient was prescribed 2 g of amoxicillin to be taken 1 hour before surgery. After adequate local anesthesia, the buccal flap was reflected such that the vertical incisions were almost parallel (Figure 4). The root stump was carefully extracted with the help of periotomes. The extraction socket was modified to receive a tapered implant (Replace Select, Nobel Biocare USA Inc) of 4.3 mm diameter and 13 mm length. The length of implant was chosen to ensure engagement of at least 3 mm of bone beyond the apex of the extraction socket. The implant was placed about 3 mm apical to the gingival margin of the adjacent tooth. At least 2 coronal threads and the collar of the implant were exposed on the buccal, and the thickness of the residual buccal ridge was about 1 mm for almost half the length of the implant (Figure 5). The buccal surface was grafted with Bio Oss and covered with Bio Gide. The buccal flap was coronally repositioned after incising the periosteum horizontally. Primary closure was achieved by a crestal horizontal mattress suture and interrupted 4/0 silk sutures on the vertical releasing incision. The patient was asked to continue amoxicillin 500 mg TDS for 1 week and to use chlorhexidine mouthwash for the next 3 weeks. Sutures were removed after 2 weeks. Stage 2 surgery to uncover the implant was carried out after 4 months. The implant was found to be stable to hand tightening of the healing abutment. The patient was then referred back to the prosthodontist for the definitive prosthesis in the form of a porcelain fused-to-metal crown (Figure 6).

A 28-year-old, medically healthy woman presented with a traumatic fracture of tooth 42. The tooth was deemed unrestorable because of a subgingival fracture (Figure 7). The patient consented to the placement of implant immediately following extraction. A prescription for 2 g amoxicillin to be taken 1 hour before surgery was given. Buccal and lingual anesthesia was achieved, and the tooth was carefully extracted with the help of periotomes and the crestal bone was preserved. Based on clinical evaluation, the surgeon decided to place the implant without reflecting a buccal flap. However, during implant site preparation, the surgeon felt the vibrations of the drill under the buccal flap and suspected perforation of the buccal cortex (Figure 7). A full-thickness flap with slightly divergent vertical incisions was reflected. Perforation of the cortex was evident in the middle third of the osteotomy site. It was decided to proceed with implant placement since adequate bony housing was present. A Branemark implant of 3.75 mm diameter and 11.5 mm length was inserted and torqued to about 30 Ncm, and adequate primary stability was achieved. The buccal perforation was grafted with Bio Oss and covered with a Bio Gide membrane (Figure 8a). The buccal flap was coronally repositioned after adequate release of the buccal periosteum, and primary closure was achieved with interrupted 4/0 vicryl sutures (Figure 8b). The patient was instructed to take amoxicillin 500 mg TDS for 1 week and to use chlorhexidine mouthwash for 3 weeks. Subsequent healing was uneventful.

Stage 2 surgery to uncover the implant was carried out after 4 months. The buccal flap was repositioned apically to match the original mucogingival margin. Periapical radiographs confirmed preservation of adequate interproximal bone height (Figure 9).

In all the patients, the root stumps were deemed unrestorable. The extraction procedure was aided with periotomes to avoid excessive expansion of the extraction socket thereby jeopardizing the primary stability of implant. This also helped reduce trauma to the thin buccal cortices.

The periapical lesion in the case of patient 1 was deemed to be chronic in nature. This conclusion was based on the absence of any signs and symptoms of active infection. In addition, current periapical radiographs were compared with previous radiographs recorded about 2 years before. It was apparent that there was no increase in the size of the lesion. Successful immediate implants have been reported in the presence of chronic periapical pathosis in animal studies23 and human case series.24 It is thus important that at the site for immediate implantation with evidence of periapical pathosis, all possible care should be taken to ensure that the lesion is chronic in nature and active infection is ruled out.

Because of the proximity of the mental foramen in the case of patient 1, it was not possible to engage 3 mm of bone apical to the extraction socket, as has been proposed to achieve adequate primary stability.25^,26 However, the narrow form of the extraction socket and the cylindrical form of the implant ensured that adequate primary stability was achieved (Figure 2).

Preservation of proximal bone level and improvement in the contour of the buccal bone were made possible by grafting the site with a bone substitute and covering it with a resorbable collagen barrier membrane. This improved the esthetic outcomes of the procedure in all 3 cases. Although the evidence on the use of such procedures, or otherwise, is not still very clear, the authors feel that all possible efforts should be made to avoid any possible esthetic complications in the future.

In patient 2, the vertical releasing incisions were planned to be parallel. This was to aid coronal repositioning of the flap to achieve closure and prevent overlap of flap margins so as to avoid excessive scarring and irregular tissue contour (Figures 4 and 5). On the other hand, in patient 1, the vertical incisions were kept divergent to prevent trauma to the mental nerve and to have adequate access and visibility to identify the mental foramen (Figure 2). It is thus important to plan the flap design according to the needs of individual patients.

Preservation of crestal bone height has been proposed to be one of the major advantages of implants placed in extraction sockets. This is evident from periapical radiographs taken after stage 2 surgery and with the prosthesis in place (Figures 2 and 9).

In all 3 patients, a submerged healing protocol was used. This was primarily dictated by the choice of implant system by the prosthodontist. In all these cases, coronal repositioning of the buccal flap aided crestal closure. However, at the uncovering stage, the flap was again repositioned apically to its original location to match the contour of the existing mucogingival junction. Apical repositioning at this stage also ensures that an adequate amount of keratinized tissue will be present on the buccal surface of the implant (Figure 6).

All 3 patients were prescribed 2 g amoxicillin 1 hour before surgery and continued on 500 mg amoxicillin TDS for another week. It is important that when flaps are reflected, there is adequate antibiotic concentration in the body fluids to combat the insurgence of oral bacteria. In addition, when bone substitutes are used, they may get contaminated by oral microflora during placement. It is thus important that adequate antimicrobial concentration is present in surrounding tissue fluids to prevent infection of the bone grafts. Subsequent infection of the site is prevented by a daily dose of antibiotics and an antimicrobial mouthwash.

Based on the review of the existing literature, it is concluded that implant placement in fresh extraction sockets is a viable treatment option and may serve to reduce overall treatment time. Predictable healing may be achieved in cases of submerged as well as transmucosal implants placed in fresh extraction sockets.

The role of guided bone regeneration in the healing of marginal voids seems to be controversial. While adequate osteointegration is achieved with or without guided bone regeneration, evidence does suggest that the use of bone substitutes and barrier membranes may serve to maintain the level of gingival tissues and thus improve esthetic outcomes.

When soft tissue closure over immediate implants is achieved by coronal advancement of the buccal flap, it is important that at the time of uncovering of the implant, the flap should be repositioned apically to match the adjacent gingival contour.