Implant

The Immediate Dental Implant

Gordon L. Douglass, DDS, and Robert L. Merin DDS, MS

Copyright 2002 Journal of the California Dental Association.

Authors

Gordon L. Douglass, DDS, maintains a private practice in Sacramento, Calif.

Robert L. Merin, DDS, MS, is the immediate past president of the California Society of Periodontists. He is also a lecturer at the University of California at Los Angeles School of Dentistry and a consultant for the West Los Angeles Veterans Administration. He maintains a private practice in Woodland Hills, Calif. Dr. Merin is a diplomate of the American Board of Periodontology and a staff members of West Hills Hospital and Northridge Hospital.

Numerous clinical studies have shown that dental implants can be placed immediately in extraction sockets with success when sites are carefully selected. Dental implants have been placed at the time of extraction with a variety of techniques. All the techniques report survival rates of 94 percent to 100 percent over a varied healing period of three months to approximately seven years. This article will review clinical criteria for determining patient selection for immediate implants and the advantages and disadvantages of immediate implant placement.

During the past 10 years, numerous clinical studies have shown that dental implants can be placed immediately in extraction sockets with success when sites are carefully selected. Dental implants have been placed at the time of extraction with a variety of techniques including without augmentation, with bone grafting, with bone grafting and a barrier membrane, and with and without primary closure. The techniques report survival rates of 94 percent to 100 percent over a varied healing period of three months to approximately seven years.^1-7 Investigators have reported high success rates with all type of implants, including screw, cylinder, Hydroxylapatite-coated, tapered, and single-stage.

This article will review the important clinical criteria for determining patient selection for immediate implants and the advantages and disadvantages of immediate implant placement. It will also discuss the clinical steps for the placement of dental implants in extraction sockets. The single-tooth implant restoration has been the most common immediate implant application, but immediate implants have also been successfully utilized in full-arch restorations.⁸ Single-rooted teeth, predominately incisors and premolars, have been the most frequent sites for immediate implants; but a study by Schwartz-Arad and colleagues evaluated molar immediate implants and found a success rate similar to healed molar sites in carefully selected cases.⁹

Patient Evaluation

The first step in determining whether immediate implant placement is a reasonable clinical choice is evaluation of the potential implant site. Several classification systems have been proposed by a variety of authors, including Salamma, Gelb, and Becker.^10-12 All the systems provide criteria for evaluating the bony morphology for immediate implant placement. The ideal extraction site for immediate implant placement is one where there is little or no periodontal bone loss on the tooth that is to be extracted, such as a tooth with endodontic involvement, root fracture, root resorption, periapical pathology, root perforation, or unfavorable crown to root ratio(not due to periodontal bone loss). In all studies, the investigators chose bony three to four walls and sufficient bone to stabilize the implant. Most researchers report desiring at least 3 to 5 mm of bone beyond the apex and a bony length of 10 mm or greater for immediate implant placement (Figure 1). There is general consensus that bony defects with two and three walls missing or severe labial and circumferential defects are not suitable for immediate implant placement. Wilson showed that the horizontal or circumferential component of the peri-implant defect was a critical factor relating to the final amount of histologic bone-implant contact, and that horizontal defects of less than 1.5 mm do not need membranes to obtain histologic osseointegration¹³ (Figure 2).

Therefore, immediate implant placement should be limited to those defects that have three- and four-walled sockets, minimal periodontal bone resorption, sufficient bone to stabilize the implant, and minimal circumferential defects. Initial implant stability is the most critical factor in implant osseointegration, therefore an ideal site is one with significant alveolar bone around the socket enabling the implant to fill the socket space (Figure 3). Ivanoff and colleagues have shown that early mobility of implants greatly reduces their integration and clinical success.¹⁴

Clinical Procedure

Tooth Extraction

The first step in immediate implant placement after case selection is an atraumatic extraction. Every attempt should be made to minimize trauma to the alveolus during the extraction. The use of a minisurgical blade to make the initial sulcular incision around the tooth will facilitate separating the soft tissues from the root and cutting the periodontal ligament. In many cases, the sulcular incision will be the only incision needed. The periodontal ligaments can be further separated from the tooth with a periotome, which will help prevent fracture of the alveolus (Figure 4). Once the tooth has been loosened with the periotome, if there is adequate tooth structure, the tooth can be carefully removed with extraction forceps. If there is not adequate tooth structure to grip with forceps or rongeurs, then the extraction may be attempted with the periotome alone or by sectioning the root so that the remaining root fragments can be extracted without placing pressure on the alveolus. The socket is then debrided with curettes or rotary instruments. The resulting extraction socket is evaluated for osseous defects. If all four walls are intact and the circumferential defect is less than 1.5 mm, an implant well may be placed without the need for bone grafting or augmentation. If three or more walls are present or if the circumferential defect is greater than 1.5 mm, an implant may be placed; but bone grafting and protection of the socket with a membrane is recommended.

Implant Osteotomy

The next step is the preparation of the extraction area and the apical bone for the placement of the implant. The first step in the dental implant placement is the beginning of an osteotomy with a round bur or pilot drill. If the site is a maxillary anterior tooth, the osteotomy must be kept on the palatal aspect of the alveolus to prevent perforating the buccal plate. Once the osteotomy is complete to the desired depth with at least 3 to 5 mm of intimate implant to bone contact, an implant is placed. The implant must be stable within the osteotomy with no mobility. The implant may touch all of the bony walls of the extraction site but should not place undue pressure upon thin alveolar walls (Figure 5). Kohal and colleagues have shown that pressure of the implant on the bony walls of the alveolus can result in microfractures and early crestal bone loss.¹⁵ The ideal situation would be for the implant to be in contact with the socket without putting undue pressure on the socket walls unless the alveolus is very thick, leaving no gap between the occlusal part of the implant and surrounding socket walls (Figure 5). In other words, the postoperative radiographic appearance of an ideal immediate implant placement would look the same as a standard implant placement (Figure 6).

The Implant to Socket Wall Space

The space between the implant and socket wall has been an issue of concern and controversy. Studies have shown that close adaptation of the implant to socket wall promotes greater osseointegration^13,16 (Figure 7). Additionally, in areas where there is a wide space from the implant to socket wall, better bone healing is achieved when an occlusive membrane is placed over the socket. In clinical studies, investigators have utilized a wide variety of techniques -- including the use of a bone graft to fill the gap and/or the use of an occlusive membrane to prevent epithelial perforation into the space between the implant and the socket wall -- to aid in the healing of this space.^17-20 Bone healing in an implant osteotomy proceeds apical to coronal, therefore the coronal aspect becomes the most critical in the healing. An implant that appears to be clinically stable may have some fibrous tissue attachment at the coronal margin rather than true osseointegration, and this may not be detectable for a long time.

Current research favors the use of a barrier if a significant gap exists between the implant and the socket wall. Numerous occlusive barriers have been used, both resorbable and nonresorbable, to prevent epithelial migration into the socket area.^21,22 In early studies, woven e-PTFE membrane exposure was a significant complication of membrane placement.²³ Newer, more-stable resorbable membranes allow membrane exposure without complication. Certain barriers -- porcine collagen and freeze-dried dermas, and laminar freeze dried bone -- can be used in techniques that do not require primary closure²⁴ (Figure 8).

Historically, most clinical studies have used primary closure of the flaps over implants placed in extraction sites. Becker and Becker used the inner portion of e-PTFE membrane as an occlusive barrier over immediate implants in four patients without primary closure.²⁵ Rosenquist used a synthetic resorbable membrane as an occlusive barrier in 10 patients and a laminar freeze dried bone membrane as an occlusive barrier in 25 patients, without primary closure.¹⁰ The advantage of not having to obtain primary closure is the preservation of the gingival tissues (Figure 8f). The advantage of a resorbable membrane is that it does not have to be removed, and the collagen membranes and laminar freeze dried bone show excellent tissue compatibility. For single-stage implants, both resorbable and nonresorbable barriers have been used to cover the implant-to-socket-wall gap.^26-29

Another choice is to use a single-stage implant that extends into the gingival space, or a healing cap or custom healing component on a two-stage implant, all of which will now fill the soft tissue portion of the socket completely or partially (Figures 9 and 10). The concern arises when a significant gap exists between the implant and the socket and the implant structure or healing cap is going to extend through the socket. Research favors the use of an occlusive barrier or membrane to protect the healing socket area.³⁰

Postoperative Management

A temporary prosthesis, either removable or fixed, can be placed over the implants. However, a removable prosthesis should not put pressure on the implant or it will result in premature loading of the implant. Premature loading or vibration of dental implants has been shown to delay osseointegration and retard bone healing.

Recently, there have been studies evaluating immediate loading of immediate placed dental implants.³¹ This has primarily been done where there are four or more implants extending around a curve that are rigidly splinted together.³² The authors believe that it is premature to consider loading single implants at this time since there are significant variables that may retard implant healing. The placement of a temporary crown, even one that is out of function, transmits load to the implant. New implant surfaces have been approved by the Food and Drug Administration for loading as early as eight weeks so that the time from implant placement to the placement of a temporary crown has shortened significantly, but the greater size of the bone-to-implant gap around some immediate implants may require longer healing times. The early placement of a temporary crown on an implant and the experimentation with immediate loading should not be considered by those who do not have extensive experience in implant placement and prosthetics.

Soft Tissue Management

One of the most critical factors in implant restorative esthetics is the gingival form. The gingival tissues can be shaped and managed by the temporary prosthesis and by the provisional crown that is placed on the implant prior to placement of the final crown (Figure 11). In areas where single-stage implants or a healing cap can be used, the implant itself may help to support the gingival tissues and the interdental papillae, which are critical for implant esthetics (Figure 10). In the restoration of dental implants in the esthetic zone of the maxillary anterior teeth, it is recommended that a temporary crown be considered as part of the restorative treatment plan to help shape and form the peri-implant tissues prior to placement of the final crown (Figure 8g).

If it is possible to place the dental implant with minimal disruption of the peri-implant tissues and provide immediate support, the management of the tissues will be facilitated. The use of anatomic gingival formers or single-stage implants and the placement of implants without elevating a flap have significantly improved practitioners’ ability to readily achieve excellent peri-implant gingival form.

Advantages and Disadvantages

The primary advantages of immediate implant placement are the reduction in time of therapy, the reduction in surgical episodes, and preservation of the bone and gingival tissues. The greatest rate of bone resorption occurs during the first six months following tooth extraction unless an implant is placed or a socket augmentation procedure performed.³⁰ The early maintenance of gingival form will greatly facilitate the peri-implant gingival tissue esthetics by maintaining support for the interdental papillae (Figure 11).

The primary disadvantage of immediate implant placement is the fact that the clinician may not be able to place the implant at the time of extraction even though time has been scheduled. The patient must always be informed that although an immediate placement will be attempted, it is not guaranteed since there is always a possibility that factors such as ankylosis, bone fractures of facial plates, socket expansion during extraction, or extensive infection might make immediate placement impossible. These areas will require extraction socket healing and possible augmentation before an implant can be placed (Figures 12 and 13).

Conclusion

Dental implants that are immediately placed into carefully selected extraction sockets have high survival rates comparable to implants placed in healed sites. The immediate-placement implants provide significant advantages of less surgical procedures, shorter treatment time, and the facilitation of improved esthetics. There are significant areas of information that need to be clarified regarding the use of bone grafts and membranes around immediately placed implants and the size of the space between the implant and socket wall. Until these are clarified with evidence-based clinical studies, clinical judgment behooves dentists to use prudence in their case selection for immediate implants. There must be adequate bone to give implant stability, and the bony walls around implants should be intact on at least three of the four sides. However, with these caveats, the immediate implant has now become a significant part of implant therapy and provides for timely esthetic implant restorations.

References

1. Lazzara RJ, Immediate implant placement into extraction sites: Surgical and restorative advantages. Int J Periodont Restorative Dent 9:333-43, 1989.

2. Ashman A, An immediate tooth root replacement: An implant cylinder and synthetic bone combination. J Oral Implantol 16:28-38, 1990.

3. Parel SM, Triplett RG, Immediate fixture placement: A treatment planning alternative. Int J Oral Maxillofac Implants 5:337-45, 1990.

4. Barizilay I, Grasser GN, et al, Immediate implantation of a pure titanium implant into an extraction socket: Report of a pilot procedure. Int J Oral Maxillofac Implants 6:277-84, 1991.

5. Tolman DE, Keller EE, Endosseous implant placement immediately following dental extraction and alveoplasty: Preliminary report with 6 year follow-up. Int J Oral Maxillofac Implants 6:24-8, 1991.

6. Becker W, Becker BE, et al, Guided tissue regeneration for implants placed into extraction sockets: A study in dogs. J Periodontal 62:703-9, 1991.

7. Yukna RA, Clinical comparison of hydroxylapatite-coated titanium dental implants placed in fresh extraction sockets and healed extraction sites. J Periodontol 62:468-72, 1991.

8. Schwartz-Arad D, Chaushu G, Full-arch restoration of the jaw with fixed ceramometal prosthesis. Int J Oral Maxillofac Implants 13:819-25, 1998.

9. Schwartz-Arad D, Gorssman Y, Chaushu G, The clinical effectiveness of implants placed immediately into fresh extraction sites of molar teeth. J Periodontal 71:839-44, 2000.

10. Salama H, Salama M, The role of orthodontic extrusive remodeling in the enhancement of soft and hard tissue profiles prior to implant placement: A systematic approach to the management of extraction site defects. Int J Periodont Restorative Dent 13:313-33, 1993.

11. Gelb DA, Immediate implants surgery: Three-year retrospective evaluation of 50 consecutive cases. Int J Oral Maxillofac Implants 8:388-99, 1993.

12. Becker W, Dahlin C, et al, The use of ePTFE barrier membranes for bone promotion around titanium implants placed into extraction sockets: A prospective multicenter study. Int J Oral Maxillofac Implants 9:31-40, 1994.

13. Wilson TG, Schenk R, et al, Implants placed in immediate extraction sites: A report of histologic and histometric analyses of human biopsies. Int J Oral Maxillofac Implants 13:333-41, 1998.

14. Ivanoff C-J, Sennerby L, Lekholm U, Influence of initial implant integration of titanium implants. An experimental study in rabbits. Clin Oral Impl Res 7:120-7, 1996.

15. Kohal RJ, Hurzeler MB, et al, Custom-made root analogue titanium implants placed into extraction sockets. An experimental study in monkeys. Clin Oral Impl Res 8:386-92, 1997.

16. Lundgren D, Rylander H, et al, Healing-in of root analogue titanium implants placed in extraction sockets: An experimental study in the beagle dogs. Clin Oral Implants Res 3:136-44, 1992.

17. Todescan R, Pilliar RM, Melcher AH, A small animal model for investigating endosseous dental implants: Effect of graft materials on healing endosseous, porous-surfaced implants placed in a fresh extraction socket. Int J Oral Maxillofac Implants 2:217-23, 1987.

18. Becker W, Lynch SE, et al, A comparison of ePTFE membranes alone or in combination with platelet-derived growth factors and insulin-like growth factor-1 or demineralized freeze-dried bone in promoting bone formation around immediate extraction socket implants. J Periodontal 63:929-40, 1992..

19. Wilson TG, Guided tissue regeneration around dental implants in immediate and recent extraction sites: Initial observations. Int J Periodont Restorative Dent 12:184-93, 1992.

20. Lang NP, Bragger U, et al, Immediate transmucosal implants using the principle of guided tissue regeneration (I). Rationale, clinical procedures and 30 month results. Clin Oral Implants Res 5:154-63, 1994.

21. Gher ME, Quintero G, et al, Bone grafting and guided bone regeneration for immediate implants in humans. J Periodontal 65:881-91, 1994.

22. Sevor JJ, Meffert RM, Placement of implants into fresh extraction sites using a resorbable collagen membrane. Case reports. Practical Periodontology and Aesthetic Dentistry 4:35-41.

23. Celletti R, Davarpanah M, et al, Guided tissue regeneration around dental implants in immediate extraction sockets: Comparison of e-PTFE and a new titanium membrane. Int J Periodont Restorative Dent 14:243-53, 1994.

24. Becker W, Becker B, et al, Autogenous bone grafting of bone defects adjacent to implants placed into immediate extraction sockets in patients: A prospective study. Internat J Oral Maxillofac Implants 389-96, 1994.

25. Rosenquist B, A bioresorbable GTR membrane as occlusive barrier after placement of implants into fresh extraction sockets. A preliminary study. Submitted for publication, 1999.

26. Rosenquist B, Ahmed M, The immediate replacement of teeth by dental implants using homologous bone membranes to seal the sockets: Clinical and radiographic findings. Clin Oral Impl Res 11:572-82, 2000.

27. Cochran DL, Douglas HB, Augmentation of osseous tissue around nonsubmerged endosseous dental implants. Int J Periodontics Restorative Dent 13:506-19, 1993.

28. Bragger U, Hammerle CHF, Lang NP, Immediate transmucosal implants using the principle of guided tissue regeneration (II). A cross-sectional study comparing the clinical outcome 1 year after immediate and standard implant placement. Clin Oral Implants Res 7:268-76, 1996.

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Legends

Figure 1a. Preoperative radiograph of tooth #4.

Figure 1b. Immediately after ITI implant placement.

Figure 1c. Two and one-half years after placement. Note that tooth #3 has endodontic pathology (Implant prosthetics by James M. Herron, DDS, Woodland Hills, Calif.).

Figure 2. Close adaptation of an implant to the crestal socket wall, within 1.5 mm.

Figure 3a. Preoperative view of tooth #25.

Figure 3b. ITI narrow neck implant immediately after placement.

Figure 3c. Six months after placement (Implant prosthetics by Gregory W. Holve, DDS, Valley Village, Calif.).

Figure 4. Microsurgical scalpel (top) and periotome (bottom) can be used to help extract teeth.

Figures 5a through e. Implants are placed in extraction sites and extraction defects. Note that implants are placed at palatal aspect of the sockets with no pressure on the buccal place.

Figure 5g. The implants at uncovering.

Figure 5h. The final restorations.

Figures 6a through d. No. 11 is fractured, and #10 has irreversible mobility due to traumatic injury, which prohibits the replacement of the fixed bridge #11-15.

Figures 6e through g. Implants are placed in the extraction sites of #10 and #11 and in the #12 and #13 healed sites.

Figures 6h through k. The final implant restoration showing excellent preservation of the gingival form and no difference on the radiographs between the implants in the immediate and healed sites.

Figure 7a. Preoperative radiograph.

Figure 7b. Immediately after placement of ITI 4.8 mm implant.

Figure 7c. Ten months postoperative radiograph (Implant prosthetics by David M. Campbell, DDS, Woodland Hills, Calif.).

Figures 8a and b. Preoperative photo and radiograph showing #9 with a vertical fracture.

Figure 8c. A wide-diameter root form implant is placed, which reduces the distance between the socket walls and the implant.

Figures 8d and e. Two resorbable collagen membranes are placed, one on the buccal because of a narrow buccal late defect and one covering the implant, eliminating the need for primary closure.

Figure 8f. Healing at five weeks with preservation of gingival papillae.

Figure 8g. Temporary restoration helping shape the gingival form.

Figures 8h through j. The final restoration one year after completion.

Figure 9a. Preoperative view of tooth #21.

Figure 9b. ITI implant immediately after placement.

Figure 9c. Four months after placement. Note bone healing around neck of the implant.

Figure 10a and b. No. 7 fractured and nonrestorable.

Figures 10c and d. No. 7 an immediate implant is placed.

Figures 10d and e. Final restoration exhibiting the same gingival form as the original tooth.

Figure 11a. Preoperative #8 with a fractured root.

Figure 11b. Implant placement #8.

Figure 11c. Surgical site sutured with minimal displacement of the interdental papillae.

Figure 11d. Radiograph of implant #8.

Figures 11e and f. Temporary removable appliance used to shape and support the gingival papillae.

Figure 11g. Healing cap placed.

Figure 11h. Final crown with maintenance of interdental gingival form.

Figure 12a. Radiograph #8 shows a large radiolucency associated with a root fracture that precludes immediate implant placement.

Figure 12b through d. Extraction and augmentation of the socket.

Figures 12e and f. Healing and tissue support from the removable appliance.

Figures 12g through i. Implant placement eight months later.

Figure 12j. Implant site and uncovering.

Figures 12k and l. Implant restored with temporary crown 12 months from extraction. The two-stage approach takes considerably more time and more steps than immediate placement.

Figure 13a. Preoperative radiograph. Tooth #6 was not a good candidate for an immediate implant because the root fracture had caused too much vertical and horizontal bone loss on the facial bone.

Figure 13b. Preoperative photograph.

Figure 13c. Surgical view of missing facial bone.

Figure 13d. Photograph of extracted tooth.