Socket Augmentation: Rationale and Technique Hom-Lay Wang, DDS, MSD,* Koichi Kiyonobu, DDS, PhD,† and Rodrigo F. Neiva, DDS‡ ooth extraction results in alveo- The consequences of exodontia should not be acutely infected and be lar bone loss as a result of re- include alveolar bone resorption and completely free of any soft tissue frag- sorption of the edentulous T ultimately atrophy to basal bone of the ments before any grafting or augmen- ridge.1–4 An average of 40% to 60% of original height and width is expected edentulous site/ridges. Ridge resorp- tation is attempted. Socket bleeding to be lost after tooth extraction, with tion proceeds quickly after tooth ex- that mixes with the grafting material the greatest loss happening within the traction and significantly reduces the seems essential for success of this pro- first 2 years.5–9 This can negatively possibility of placing implants without cedure. Various types of bone grafting influence bone volume that is needed grafting procedures. The aims of this materials have been suggested for this for future dental implant placement. article are to describe the rationale purpose, and some have shown prom- Research has demonstrated that the al- behind alveolar ridge augmentation ising results. Coverage of the grafted veolar ridge at the maxillary anterior procedures aimed at preserving or extraction site with wound dressing area can be reduced by 23% in the first minimizing the edentulous ridge vol- materials, coronal flap advancement, 6 months after exodontia, and an ad- ume loss. Because the goal of these or even barrier membranes may en- ditional 11% in the following 5 approaches is to preserve bone, ex- hance wound stability and an undis- years.10 In the posterior mandible, re- sorption happens primarily in the buc- odontia should be performed to pre- turbed healing process. Future con- cal/labial direction, resulting in a lin- serve as much of the alveolar process trolled clinical trials are necessary to gual displacement of alveolar crest.10 as possible. After severance of the determine the ideal regimen for socket The rate of reduction of residual alve- supra- and subcrestal fibrous attach- augmentation. (Implant Dent 2004; olar ridges has shown to be greater in ment using scalpels and periotomes, 13:286–296) mandibular (0.4 mm/year) than in elevation of the tooth frequently al- Key Words: alveolar ridge augmenta- maxillary arches (0.1 mm/year).11 As a lows extraction with minimal socket tion, socket preservation, exodontia, consequence, alveolar ridge atrophy wall damage. Extraction sockets dental implants may prohibit optimal implant place- ment, compromising the final esthetic and functional outcomes.12 traction sockets.16–18 Generally, these sorbable barrier membranes and ex- Augmentation of the residual al- procedures are primarily aimed at pre- tractions alone. At 6 months, signifi- veolar socket at the time of tooth ex- serving the current bone level and cantly less crestal bone loss (Ϫ0.38 traction (ie, socket augmentation, hopefully regenerating new bone. mm vs. Ϫ1.50 mm), more internal socket preservation, ridge preserva- This article presents the rationale socket fill (Ϫ5.81 mm vs. Ϫ3.94 mm), tion) has been evaluated in many stud- behind socket augmentation for future 13–15 and less horizontal ridge resorption ies. Multiple bone graft regimens implant placement and describes a (Ϫ1.31 mm vs. Ϫ4.56 mm) were and techniques have been suggested to technique that has shown to not only found in the membrane group than in minimize alveolar ridge atrophy and to facilitate tooth extraction with mini- the control group.19 As this study sug- evaluate new bone growth within ex- mal damage to the surrounding ana- gested, successful early alveolar ridge tomic structures, but also to improve augmentation (preservation) proce- alveolar bone quality and quantity. *Professor and Director of Graduate Periodontics, Department dures may reduce, or eliminate, the of Periodontics/Prevention/Geriatrics, School of Dentistry, University of Michigan, Ann Arbor, MI. need for future ridge augmentation. †Private practice, Tokyo, Japan; and formal Visiting Research Fellow, Department of Periodontics/Prevention/Geriatrics, RATIONALE Bone healing and subsequent new School of Dentistry, University of Michigan, Ann Arbor, MI. ‡Clinical Assistant Professor, Department of The rationale for alveolar ridge bone formation after grafting take Periodontics/Prevention/Geriatrics, School of Dentistry, University of Michigan, Ann Arbor, MI. preservation relies on the knowledge place through osteogenesis, osteoin- that alveolar ridge resorption is an un- duction, and/or osteoconduction.20–22 ISSN 1056-6163/04/01304-286 1 Implant Dentistry avoidable sequela of tooth loss. Lek- Osteogenic graft materials supply via- Volume 13 • Number 4 Copyright © 2004 by Lippincott Williams & Wilkins ovic et al. compared the outcome of ble osteoblasts that form new bone, DOI: 10.1097/01.id.0000148559.57890.86 alveolar ridge preservation using ab- whereas osteoinductive grafts stimu- 286 SOCKET AUGMENTATION late pluripotential mesenchymal cells ridge atrophy have been made.43–46 lial and connective tissue attachments to differentiate into osteoblasts that These grafting materials have shown to the tooth surface. Utilization of can form new bone. Osteoconductive to not only aid in osteoconduction of sharp instruments for this purpose graft materials, however, merely act as osteogenic cells by preserving the minimizes trauma and loss of the gin- a lattice for cell growth, permitting space and excluding unwanted cells gival tissues. osteoblasts from the wound margins to from the wound, but also to promote Periotomes are then applied to infiltrate the defect and migrate across formation new bone.47–50 Iasella et al. sever the subcrestal attachment appa- the graft.23 Autologous grafts are con- conducted a randomized, controlled, ratus. Straight periotomes are indi- sidered to be the ideal material for masked clinical trial in 24 patients. cated for use on single-rooted teeth, bone grafting procedures because it Subjects received either extraction whereas angled periotomes allow ac- possesses osteogenic, osteoinductive, alone or socket augmentation using cess to posterior multirooted teeth. and osteoconductive properties.24 tetracycline hydrated freeze-dried These instruments are used in a similar Transplantation of living cells in- bone allograft (FDBA) and a collagen manner for extraction of intact teeth or creases the possibility of retained cell membrane. Histologic analysis dem- removal of retained root fragments. viability and graft revasculariza- onstrated greater bone formation in The instrument is used first to com- tion.25–28 In addition, autologous grafts augmented sites after a 6-month heal- plete rupture of the gingival fibers at do not present a risk of disease trans- ing period. The most predictable the cervical area of the tooth (Fig. 1a). mission because donor and recipient maintenance of ridge width, height, During this procedure, the long axis of are the same individual.29 However, and position was achieved when a the blade should be angled converging they do increase the risk of additional socket augmentation procedure was at approximately 20° from the tooth pain, infection, and donor site morbid- used.50 However, some reports have long axis. This maneuver ensures that ity because an additional surgical pro- shown negative results when a alveo- the tip of the periotome blade is lo- cedure is necessary for harvesting.23 lar ridge preservation was attempted, cated within the crest of the alveolar Hence, bone substitutes have gained possibly as a result of use of inade- bone only, thus preventing the blade increasing acceptance as alternatives quate techniques and/or materials.51–54 from sliding out of the ridge and lac- to autologous bone for patients requir- For example, Zubillaga et al. evalu- erating the gingiva. The blade is thrust ing bone augmentation in an effort to ated a combination of demineralized to the depth of the gingival sulcus and decrease the morbidity associated with freeze-dried bone allograft (Re- the gingival attachment is severed cir- autologous graft harvesting.30 Allo- genafill; Regeneration Technologies, cumferentially. It is necessary to re- grafts, xenografts, and alloplasts come Inc., Alachua, FL) and a bioabsorb- peat this procedure to ensure that all in many forms, and data support their able membrane (Resolut XT; W.L. gingival fibers are severed. The instru- safety, clinical applicability, and low Gore & Associates, Inc., Flagstaff, ment is then inserted into the peri- antigenicity.31 Bone graft materials AZ) for socket augmentation. The odontal ligament space and moved re- have been used to augment bony de- negative results observed were attrib- peatedly in a mesiodistal direction, on fects adjacent to dental implants and to uted to the slow resorption of the gel- the whole circumference of the root, repair chronic extraction socket de- atin carrier of the graft material.54 severing the periodontal ligament im- fects, with and without the use of bar- mediately below the alveolar crest. rier membranes.32–34 When combined The periotome is then pushed further with barrier membranes, bone graft TECHNIQUE down into the periodontal ligament to- materials have also shown to prevent After a complete medical history ward the root apex. It is possible to collapse of the barrier membrane.35–38 has been reviewed, and no contraindi- reach up to two thirds of the root Xenografts and alloplasts