H a rd a n d So f t Ti s s u e Surgical Complications in Dental Implantology Shahid R. Aziz, DMD, MD KEYWORDS Hard tissue Soft tissue Implant Complications Nerve injury Peri-implantitis
KEY POINTS
No matter what measures are taken, doctors will sometimes falter, and it isn’t reasonable to ask that we achieve perfection. What is reasonable is to ask (is) that we never cease to aim for it. —Atul Gawande, Complications: A Surgeon’s Notes on an Imperfect Science
INTRODUCTION As with all surgical procedures, complications will occur. One can expect that the longer one is in surgical practice, the more procedures performed, there will be complications. Dental implantology is no different. The purpose of this article is to discuss surgical complications associated with the placement of dental implants, specifically focusing on how they occur (etiology), as well as their management and prevention. Dental implant surgical complications can be classified into those of hard and soft tissues.
Soft Tissue Complications Mandibular nerve injury The third branch of the trigeminal nerve (mandibular nerve or inferior alveolar nerve, IAN) is at constant risk of injury secondary to any mandibular
oral and maxillofacial surgical procedure. This nerve provides sensation to the lower lip and chin, as well as innervating the associated dentition. It also provides motor innervation for the muscles of mastication and sensation to the tongue. Injury to the IAN can result in partial or complete paresthesia, analgesia, anesthesia, or in rare cases dysesthesia, to the structures it innervates.1 The incidence of IAN injury secondary to dental implant surgery is variable, with a range of 0% to 44% in the literature.2 The etiology of IAN injury is usually associated with inadequate planning or overzealous implant placement, with injury occurring as a result of either miscalculation of nerve position from the preoperative radiographic assessment or injury via placing implant drills or fixture too apical into the nerve canal. In rare cases, the IAN can be injured from local anesthetic injection (injection injury) or retraction of the gingival flap causing stretching of the mental nerve (terminal branch of the IAN). In the edentulous/atrophic mandible, the mental foramen may be located at the crest of the alveolar ridge, and it can be at a higher risk of being traumatized from incision and flap elevation. Prevention of IAN injury is directly related to proper and thorough preoperative implant planning.
Department of Oral and Maxillofacial Surgery, Rutgers School of Dental Medicine, 110 Bergen Street, Room B854, Newark, NJ 07103, USA E-mail address: [email protected] Oral Maxillofacial Surg Clin N Am - (2015) -–http://dx.doi.org/10.1016/j.coms.2015.01.006 1042-3699/15/$ – see front matter Ó 2015 Elsevier Inc. All rights reserved.
oralmaxsurgery.theclinics.com
Complications can be avoided with proper surgical technique and treatment planning. Soft tissue complications include nerve injury, flapless surgical complications, and sinus complications. Hard tissue complications include complications from bone grafting and peri-implantitis.
2
Aziz Ideally Cone beam computerized tomograms (CBCTs) or conventional computed tomography (CT) scans can be utilized as part of the treatment planning phase to not only plan for implant size, location, and vector of placement, but also to identify and avoid the mandibular canal. Proper measurements and the use of implant planning software are all excellent tools in planning ideal implant placement that avoids injury to the IAN. If a panoramic radiograph is used, the surgeon must be able to adequately visualize the course of the IAN in the mandibular body and parasymphysis regions. When measuring the distance of the alveolar ridge to mandibular nerve canal, one must factor in up to a 25% magnification (magnification factor of 1.25) on the panoramic radiograph. As such, clinical bone height can be more adequately planned by dividing radiographic bone height by the magnification factor (usually 1.25) according to the formula: Clinical bone height 5 radiographic bone height/ magnification factor For example, if the measured radiographic bone height is 13 mm, dividing by 1.25 gives a clinical measurement of 10.4 mm, then the use of an implant fixture less than 10.4 mm will ensure that the IAN will be protected. Intraoperatively, utilizing CT-based surgical guides (presurgically fabricated based on CT evaluation during the treatment planning phase with precise CT-based placement of the dental implant with depth control away from IAN) can also protect the IAN. Other options include taking radiographs step by step during the procedure with either a drill or positioning locator in place to ensure that the drilling has not gone more apical than planned. If radiographically the IAN canal is violated or it appears that a drill has gone too apical, options include using shorter drills for a shorter implant, aborting the procedure with or without a bone graft, or
redirecting fixture placement. If the radiograph indicates that the canal is violated, clinical assessment can give clues to extent of injury (if any). Violation or injury to the IAN will cause electric shock like pain in even those with good nerve block; the appearance of significant (though transient) bleeding may occur out of osteotomy. Use of local infiltatration as opposed to nerve block can also maintain patient feedback while drilling in the posterior mandible. Topical dexamethasone has been suggested to reduce inflammation in the site of injury. If there is witnessed gross injury to the mandibular canal or IAN, then immediate referral to a microsurgery specialist for treatment is indicated. An immediate postoperative panoramic radiograph must be taken to assess the placement of the implant(s). If the IAN canal appears encroached, the implant must be backed out or removed. If the implant appears positioned clear of the canal, but the patient has a consistent paresthesia that has not improved within 2 to 3 days after surgery, it is reasonable to either observe or obtain a CBCT to assess if the canal was damaged during placement. If there appears to be damage to the canal (most likely from overzealous drilling) referral to a microsurgery specialist is indicated. If there is no injury to the canal, but the paresthesia persists and the implant appears close to the canal, backing out or removing the implant is indicated. If there does not appear to be encroachment of the implant on or injury to the mandibular canal, postoperative edema maybe the cause of the paresthesia, and a course of corticosteroids may be helpful. If there appears to be no improvement, then consideration of an injection injury must be considered and referral to a microsurgery specialist (Fig. 1). Sinus/nasal floor perforation Perforation of the maxillary sinus and nasal floor occur, usually secondary to poor planning or
Fig. 1. (A) Panoramic radiograph of implant placed into right mandibular canal. (B) Buccal plate bone window created with implant into mandibular canal and neurovascular bundle. (C) Coronal CT scan with implant into canal. (Courtesy of Dr Vincent Ziccardi, Newark, NJ.)
Surgical Complications in Dental Implantology surgical technique. However, in both cases, the degree of perforation dictates treatment. If the perforation occurs with the pilot drill and is minor, often shortening the length of the subsequent osteotomies is enough to avoid significant damage to the underlying membrane. Larger perforations may be treated via internal sinus lifts or placing collagen membrane or infusing rhBMP graft (Medtronic, Minneapolis, Minnesota) at the apex of the osteotomy. In the situation of large perforations, abortion of the placement of the implant is required, replaced with collagen membrane placement at the apex of the osteotomy with bone grafting to avoid sinus complications. Nasal floor perforations may be associated with minor nasal bleeding, which is often transient. In both situations, sinus precautions postoperatively, as well as appropriate antibiotic coverage, is indicated. Displacement of the implant into the maxillary sinus demands immediate foreign body removal. If unable to remove through the existing implant osteotomy, a Caldwell-Luc approach is indicated for retrieval of a displaced implant. Sinus precautions (antibiotics with sinus flora coverage and decongestants) are indicated for 7 to 10 days after the procedure (Fig. 2). Flapless surgery complications The flapless surgical technique is designed to minimize surgical bleeding and postoperative discomfort. Placement typically utilizes a tissue punch to remove gingiva in the area of implant placement. A major disadvantage of this technique is not being able to fully appreciate the anatomy of the alveolar bone. This is a blind surgical technique; perforation of the buccal or lingual/palatal cortices may occur without the surgeon’s knowledge, compromising the fixture. Further, the inability to visualize the crestal bone may result in implants that are too shallow or placed too deep, creating prosthetic problems. Prevention of these
complications is primarily through proper patient selection and good implant treatment planning. Preoperative CBCT with virtual surgical planning for implant placement is often indicated. Assessment of the alveolar width of the ridge and associated curvature can be done via a CBCT. A virtual surgically planned implant guide can eliminate many of these problems as well as ensure placement of the implant into the presurgically determined ideal position and depth. Plain dental radiographs immediately following implant placement prior to closure can also help determine whether ideal vertical placement of the implant has been achieved; if placed too shallow or deep, the implant position can be adjusted.
Hard Tissue Complications Complications of recipient site in autogenous bone grafting Autogenous bone grafting of atrophic alveolar ridges in preparation for implant reconstruction is a standard of care in oral and maxillofacial surgery. There are multiple donor sites, including iliac crest, calvarium, rib, tibia, as well as intraoral sites (eg, mandibular symphysis, mandibular ramus, and maxillary tuberosity). Techniques of harvest and complications specific to harvest are beyond the scope of this article. However, complications of the recipient site will be discussed. Recipient site complications can be broken down into 4 areas:
Graft contamination Wound dehiscence Infection Resorption
Graft contamination is usually associated with poor handling after harvest. Maintaining principles of sterility is integral to successful graft placement. Once the graft is harvested, avoid using gloves to manipulate the graft; rather transport graft via a
Fig. 2. (A) Displacement of implant at time of placement into right maxillary sinus. (B) Radiographic presentation at time of retrieval via Caldwell–Luc approach. (C) Caldwell Luc approach used for retrieval resulting in Oro-antral fistula requiring second procedure to correct.
3
4
Aziz secure clamp or forcep from the donor site to a sterile normal saline-filled container. Utilization of sterile water or other transport medium fluids can cause osmotic cell lysis of the graft.3 If the graft become contaminated, it is best to discard and reharvest. Wound dehiscence is tantamount to graft failure due to saliva contamination. Incision line dehiscence usually occurs as a result of lack of a tension-free closure or sharp edges of the graft perforating the overlying soft tissue. Considerations prior to grafting include evaluating the soft tissue envelope of recipient area, specifically considering the quality and amount of keratinized mucosa, tissue thickness, and presence of scar tissue. It is important to remember that bone grafting increases volume of underlying bone in the grafted site; evaluating the soft tissue prior to grafting is essential to ensure that the recipient site soft tissue can accommodate the bone graft in a tension-free fashion. In situations where it is suspected that the soft tissue quantity or quality may be questionable, soft tissue grafting or tissue expansion procedures may be indicated. This may provide better quality keratinized tissue in the recipient site (palatal grafts are ideal to increase keratinized tissue). Other issues associated with wound dehiscence include incision design. Ideally, most incisions should be placed on the crest of the alveolar ridge, as this allows for maximal blood supply to the flap. Flaps placed too buccal, palatal, or lingual may have decreased vascular supply, risking necrosis of the flap.4 Another issue to consider is that by extending existing tissue to cover graft sites, there may be resulting obliteration of the associated vestibule; as such, patients should be made aware of need for a secondary vestibuloplasty as needed. Smoking or existing prosthesis irritation can also be associated with incision dehiscence. When a dehiscence occurs, treatment options are often based on degree of dehiscence. Small pin-point dehiscences can often be easily managed by local wound care (warm salt water rinses and good hygiene). Larger dehiscences may require nonalcohol-based rinses (alcoholbased rinses can be toxic to nonvascularized bone grafts), local wound care, oral antibiotics to minimize infection risk, and/or debulking of the graft to allow for primary closure. Necrotic graft material should be debrided (Fig. 3). Infections of bone grafts are often associated with poor sterile technique. Prevention of infection is paramount for success of the graft. Appropriate antibiotic coverage intraoperatively and postoperatively is indicated, as is good hygiene and judicious use of alcohol-free oral rinses.
Fig. 3. Dehiscence of soft tissue over graft resulting in graft exposure to oral cavity and subsequent failure. (Courtesy of Dr Hani Braidy, Newark, NJ.)
Resorption of bone grafts is common and often has to do with lack of revascularization, often secondary to salivary contamination from wound dehiscence. Cortical bone typically acts as an osteoconductive scaffold for new bone formation. Cancellous bone cells produce bone osteoid, or new bone. The cancellous portion of grafts revascularize much more rapidly than cortical bone.5 Further, more porous cortical grafts are found to resorb more when compared with denser cortical grafts. Preparing the recipient bed is important to facilitate revascularization. Perforation of the graft site releases growth factors and improves revascularization of the graft. Block grafts require rigid fixation for revascularization. Micromovement can lead to poor revascularization. Fixation can usually be accomplished using a lag screw technique with small titanium screws. When there is resorption of a bone, graft options are limited to trying to use a smaller implant versus regrafting (Fig. 4). Peri-implantitis “Peri-implantitis is a inflammatory process causing destruction of the hard and soft tissue surround the dental implant.”6 This results in loss of soft tissue and hard tissue support around the dental implant. The etiology is associated with a bacterial biofilm coating the implant. This film has been shown to attach and colonize within minutes to an hour after placement and then exponentially proliferate.7 Bacteria are usually part of the normal oral flora. The inflammatory response to this biofilm is what causes the bone loss and soft tissue loss. Clinically, implants associated with periimplantitis can be clinically stable with only radiographic evidence of bone loss, or symptomatic: mobility of implant, purulent or sero-sanguinous
Surgical Complications in Dental Implantology
Fig. 4. (A) Immediate postoperative panoramic radiograph of symphyseal graft harvested to reconstruct buccal defect in tooth #19/20 site. (B) Resorption of graft; sharp edge or superior aspect of graft resulting in wound dehiscence and subsequent resorption of graft.
drainage, foul odor, gingival bleeding, or rarely, pain. In addition, surrounding tissues may appear edematous or tender on examination. On radiographs, there is loss of alveolar bone height; the degree will indicate presence or absence of mobility to the implant. Prevention of peri-implantitis is primarily on the patient’s shoulders to maintain excellent oral hygiene. The surgeon, however, needs to educate the patient on hygiene importance and procedure; further the surgeon and patient must work in concert with the general dentist/dental hygienist in maintaining placed implants and preventing periimplantitis. Furthermore, once the endosseous implants have been restored, it is the responsibility of the restorative dentist to ensure that the dental prosthesis is easily cleansable and does not create areas for plaque build-up around the implants. Endosseous implants developing peri-implantitis (clinical suppuration or bone loss radiographically) that are still immobile should be attended to quickly to prevent their failure. Strategies often are based on the degree of bone loss or probing depth. Minimal bone loss and probing depths of less than
4 mm usually require plaque and calculus removal, polishing of the implant crown, and increased oral hygiene visits annually. Mild bone loss and probing depths of 4 to 6 mm require, in addition to increased hygiene visits, chlorhexidine rinses daily or the application of chlorhexidine gels to the affected area. Applying citric acid directly to the exposed implant threads can be considered to detoxify the area. Typically, daily rinsing should be continued until improvement (decreased probing depths) is noted. If probing depths increase beyond 6 mm of significant bone loss (implant still stable), then in addition to hygiene and rinsing, systemic antibiotics focused on gram-negative coverage (metronidazole) is administered for 10 days. Once the any suppuration, edema, and/or infection has resolved, it is reasonable to consider guided tissue regenerative procedures with allogenic bone grafting to restore bone height around the implant.8 If the implant is restored, the restoration should be taken out of occlusion to minimize functional loads. Mobility of implants results in implant failure, and removal is required with possible bone grafting if desired (Fig. 5).
Fig. 5. (A) Panoramic radiograph at time of placement of implant. (B) Three months after placement greater than 50% bone loss.
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6
Aziz REFERENCES 1. Hassani AA, Aighamdi AS. Inferior alveolar nerve injury in implant dentistry: diagnosis, causes, prevention, and management. J Oral Implantol 2010;36:401–7. 2. Misch C, Resnick R. Mandibular neurosensory impairment following dental implant surgery. Management and protocol. Oral Health J 2012;12:1–12. 3. Steiner M, Ramp WK. Short term storage of freshly harvested bone. J Oral Maxillofac Surg 1988;46:868–71. 4. Whetzel TP, Sanders CJ. Arterial anatomy of the oral cavity: an analysis of vascular territories. Plast Reconstr Surg 1997;100:582–7.
5. Manson PN. Facial bone healing and bone grafts. A review of clinical physiology. Clin Plast Surg 1994; 21:331–48. 6. Mombelli A. Microbiology and antimicrobial therapy of peri-implantitis. Periodontol 2000 2002;28: 177–89. 7. Furst MM, Salvi GE, Lang NP, et al. Bacterial colonization immediately after installation on oral titanium implants. Clin Oral Implants Res 2007;18:501–8. 8. Lang NP, Tonetti MS. Peri-implantitis; etiology, pathogenesis, prevention, and therapy. Chapter 7. In: Froum S, editor. Dental implant complication. Ames (IA): Wiley-Blackwell; 2010. p. 119–31.
KEY POINTS
No matter what measures are taken, doctors will sometimes falter, and it isn’t reasonable to ask that we achieve perfection. What is reasonable is to ask (is) that we never cease to aim for it. —Atul Gawande, Complications: A Surgeon’s Notes on an Imperfect Science
INTRODUCTION As with all surgical procedures, complications will occur. One can expect that the longer one is in surgical practice, the more procedures performed, there will be complications. Dental implantology is no different. The purpose of this article is to discuss surgical complications associated with the placement of dental implants, specifically focusing on how they occur (etiology), as well as their management and prevention. Dental implant surgical complications can be classified into those of hard and soft tissues.
Soft Tissue Complications Mandibular nerve injury The third branch of the trigeminal nerve (mandibular nerve or inferior alveolar nerve, IAN) is at constant risk of injury secondary to any mandibular
oral and maxillofacial surgical procedure. This nerve provides sensation to the lower lip and chin, as well as innervating the associated dentition. It also provides motor innervation for the muscles of mastication and sensation to the tongue. Injury to the IAN can result in partial or complete paresthesia, analgesia, anesthesia, or in rare cases dysesthesia, to the structures it innervates.1 The incidence of IAN injury secondary to dental implant surgery is variable, with a range of 0% to 44% in the literature.2 The etiology of IAN injury is usually associated with inadequate planning or overzealous implant placement, with injury occurring as a result of either miscalculation of nerve position from the preoperative radiographic assessment or injury via placing implant drills or fixture too apical into the nerve canal. In rare cases, the IAN can be injured from local anesthetic injection (injection injury) or retraction of the gingival flap causing stretching of the mental nerve (terminal branch of the IAN). In the edentulous/atrophic mandible, the mental foramen may be located at the crest of the alveolar ridge, and it can be at a higher risk of being traumatized from incision and flap elevation. Prevention of IAN injury is directly related to proper and thorough preoperative implant planning.
Department of Oral and Maxillofacial Surgery, Rutgers School of Dental Medicine, 110 Bergen Street, Room B854, Newark, NJ 07103, USA E-mail address: [email protected] Oral Maxillofacial Surg Clin N Am - (2015) -–http://dx.doi.org/10.1016/j.coms.2015.01.006 1042-3699/15/$ – see front matter Ó 2015 Elsevier Inc. All rights reserved.
oralmaxsurgery.theclinics.com
Complications can be avoided with proper surgical technique and treatment planning. Soft tissue complications include nerve injury, flapless surgical complications, and sinus complications. Hard tissue complications include complications from bone grafting and peri-implantitis.
2
Aziz Ideally Cone beam computerized tomograms (CBCTs) or conventional computed tomography (CT) scans can be utilized as part of the treatment planning phase to not only plan for implant size, location, and vector of placement, but also to identify and avoid the mandibular canal. Proper measurements and the use of implant planning software are all excellent tools in planning ideal implant placement that avoids injury to the IAN. If a panoramic radiograph is used, the surgeon must be able to adequately visualize the course of the IAN in the mandibular body and parasymphysis regions. When measuring the distance of the alveolar ridge to mandibular nerve canal, one must factor in up to a 25% magnification (magnification factor of 1.25) on the panoramic radiograph. As such, clinical bone height can be more adequately planned by dividing radiographic bone height by the magnification factor (usually 1.25) according to the formula: Clinical bone height 5 radiographic bone height/ magnification factor For example, if the measured radiographic bone height is 13 mm, dividing by 1.25 gives a clinical measurement of 10.4 mm, then the use of an implant fixture less than 10.4 mm will ensure that the IAN will be protected. Intraoperatively, utilizing CT-based surgical guides (presurgically fabricated based on CT evaluation during the treatment planning phase with precise CT-based placement of the dental implant with depth control away from IAN) can also protect the IAN. Other options include taking radiographs step by step during the procedure with either a drill or positioning locator in place to ensure that the drilling has not gone more apical than planned. If radiographically the IAN canal is violated or it appears that a drill has gone too apical, options include using shorter drills for a shorter implant, aborting the procedure with or without a bone graft, or
redirecting fixture placement. If the radiograph indicates that the canal is violated, clinical assessment can give clues to extent of injury (if any). Violation or injury to the IAN will cause electric shock like pain in even those with good nerve block; the appearance of significant (though transient) bleeding may occur out of osteotomy. Use of local infiltatration as opposed to nerve block can also maintain patient feedback while drilling in the posterior mandible. Topical dexamethasone has been suggested to reduce inflammation in the site of injury. If there is witnessed gross injury to the mandibular canal or IAN, then immediate referral to a microsurgery specialist for treatment is indicated. An immediate postoperative panoramic radiograph must be taken to assess the placement of the implant(s). If the IAN canal appears encroached, the implant must be backed out or removed. If the implant appears positioned clear of the canal, but the patient has a consistent paresthesia that has not improved within 2 to 3 days after surgery, it is reasonable to either observe or obtain a CBCT to assess if the canal was damaged during placement. If there appears to be damage to the canal (most likely from overzealous drilling) referral to a microsurgery specialist is indicated. If there is no injury to the canal, but the paresthesia persists and the implant appears close to the canal, backing out or removing the implant is indicated. If there does not appear to be encroachment of the implant on or injury to the mandibular canal, postoperative edema maybe the cause of the paresthesia, and a course of corticosteroids may be helpful. If there appears to be no improvement, then consideration of an injection injury must be considered and referral to a microsurgery specialist (Fig. 1). Sinus/nasal floor perforation Perforation of the maxillary sinus and nasal floor occur, usually secondary to poor planning or
Fig. 1. (A) Panoramic radiograph of implant placed into right mandibular canal. (B) Buccal plate bone window created with implant into mandibular canal and neurovascular bundle. (C) Coronal CT scan with implant into canal. (Courtesy of Dr Vincent Ziccardi, Newark, NJ.)
Surgical Complications in Dental Implantology surgical technique. However, in both cases, the degree of perforation dictates treatment. If the perforation occurs with the pilot drill and is minor, often shortening the length of the subsequent osteotomies is enough to avoid significant damage to the underlying membrane. Larger perforations may be treated via internal sinus lifts or placing collagen membrane or infusing rhBMP graft (Medtronic, Minneapolis, Minnesota) at the apex of the osteotomy. In the situation of large perforations, abortion of the placement of the implant is required, replaced with collagen membrane placement at the apex of the osteotomy with bone grafting to avoid sinus complications. Nasal floor perforations may be associated with minor nasal bleeding, which is often transient. In both situations, sinus precautions postoperatively, as well as appropriate antibiotic coverage, is indicated. Displacement of the implant into the maxillary sinus demands immediate foreign body removal. If unable to remove through the existing implant osteotomy, a Caldwell-Luc approach is indicated for retrieval of a displaced implant. Sinus precautions (antibiotics with sinus flora coverage and decongestants) are indicated for 7 to 10 days after the procedure (Fig. 2). Flapless surgery complications The flapless surgical technique is designed to minimize surgical bleeding and postoperative discomfort. Placement typically utilizes a tissue punch to remove gingiva in the area of implant placement. A major disadvantage of this technique is not being able to fully appreciate the anatomy of the alveolar bone. This is a blind surgical technique; perforation of the buccal or lingual/palatal cortices may occur without the surgeon’s knowledge, compromising the fixture. Further, the inability to visualize the crestal bone may result in implants that are too shallow or placed too deep, creating prosthetic problems. Prevention of these
complications is primarily through proper patient selection and good implant treatment planning. Preoperative CBCT with virtual surgical planning for implant placement is often indicated. Assessment of the alveolar width of the ridge and associated curvature can be done via a CBCT. A virtual surgically planned implant guide can eliminate many of these problems as well as ensure placement of the implant into the presurgically determined ideal position and depth. Plain dental radiographs immediately following implant placement prior to closure can also help determine whether ideal vertical placement of the implant has been achieved; if placed too shallow or deep, the implant position can be adjusted.
Hard Tissue Complications Complications of recipient site in autogenous bone grafting Autogenous bone grafting of atrophic alveolar ridges in preparation for implant reconstruction is a standard of care in oral and maxillofacial surgery. There are multiple donor sites, including iliac crest, calvarium, rib, tibia, as well as intraoral sites (eg, mandibular symphysis, mandibular ramus, and maxillary tuberosity). Techniques of harvest and complications specific to harvest are beyond the scope of this article. However, complications of the recipient site will be discussed. Recipient site complications can be broken down into 4 areas:
Graft contamination Wound dehiscence Infection Resorption
Graft contamination is usually associated with poor handling after harvest. Maintaining principles of sterility is integral to successful graft placement. Once the graft is harvested, avoid using gloves to manipulate the graft; rather transport graft via a
Fig. 2. (A) Displacement of implant at time of placement into right maxillary sinus. (B) Radiographic presentation at time of retrieval via Caldwell–Luc approach. (C) Caldwell Luc approach used for retrieval resulting in Oro-antral fistula requiring second procedure to correct.
3
4
Aziz secure clamp or forcep from the donor site to a sterile normal saline-filled container. Utilization of sterile water or other transport medium fluids can cause osmotic cell lysis of the graft.3 If the graft become contaminated, it is best to discard and reharvest. Wound dehiscence is tantamount to graft failure due to saliva contamination. Incision line dehiscence usually occurs as a result of lack of a tension-free closure or sharp edges of the graft perforating the overlying soft tissue. Considerations prior to grafting include evaluating the soft tissue envelope of recipient area, specifically considering the quality and amount of keratinized mucosa, tissue thickness, and presence of scar tissue. It is important to remember that bone grafting increases volume of underlying bone in the grafted site; evaluating the soft tissue prior to grafting is essential to ensure that the recipient site soft tissue can accommodate the bone graft in a tension-free fashion. In situations where it is suspected that the soft tissue quantity or quality may be questionable, soft tissue grafting or tissue expansion procedures may be indicated. This may provide better quality keratinized tissue in the recipient site (palatal grafts are ideal to increase keratinized tissue). Other issues associated with wound dehiscence include incision design. Ideally, most incisions should be placed on the crest of the alveolar ridge, as this allows for maximal blood supply to the flap. Flaps placed too buccal, palatal, or lingual may have decreased vascular supply, risking necrosis of the flap.4 Another issue to consider is that by extending existing tissue to cover graft sites, there may be resulting obliteration of the associated vestibule; as such, patients should be made aware of need for a secondary vestibuloplasty as needed. Smoking or existing prosthesis irritation can also be associated with incision dehiscence. When a dehiscence occurs, treatment options are often based on degree of dehiscence. Small pin-point dehiscences can often be easily managed by local wound care (warm salt water rinses and good hygiene). Larger dehiscences may require nonalcohol-based rinses (alcoholbased rinses can be toxic to nonvascularized bone grafts), local wound care, oral antibiotics to minimize infection risk, and/or debulking of the graft to allow for primary closure. Necrotic graft material should be debrided (Fig. 3). Infections of bone grafts are often associated with poor sterile technique. Prevention of infection is paramount for success of the graft. Appropriate antibiotic coverage intraoperatively and postoperatively is indicated, as is good hygiene and judicious use of alcohol-free oral rinses.
Fig. 3. Dehiscence of soft tissue over graft resulting in graft exposure to oral cavity and subsequent failure. (Courtesy of Dr Hani Braidy, Newark, NJ.)
Resorption of bone grafts is common and often has to do with lack of revascularization, often secondary to salivary contamination from wound dehiscence. Cortical bone typically acts as an osteoconductive scaffold for new bone formation. Cancellous bone cells produce bone osteoid, or new bone. The cancellous portion of grafts revascularize much more rapidly than cortical bone.5 Further, more porous cortical grafts are found to resorb more when compared with denser cortical grafts. Preparing the recipient bed is important to facilitate revascularization. Perforation of the graft site releases growth factors and improves revascularization of the graft. Block grafts require rigid fixation for revascularization. Micromovement can lead to poor revascularization. Fixation can usually be accomplished using a lag screw technique with small titanium screws. When there is resorption of a bone, graft options are limited to trying to use a smaller implant versus regrafting (Fig. 4). Peri-implantitis “Peri-implantitis is a inflammatory process causing destruction of the hard and soft tissue surround the dental implant.”6 This results in loss of soft tissue and hard tissue support around the dental implant. The etiology is associated with a bacterial biofilm coating the implant. This film has been shown to attach and colonize within minutes to an hour after placement and then exponentially proliferate.7 Bacteria are usually part of the normal oral flora. The inflammatory response to this biofilm is what causes the bone loss and soft tissue loss. Clinically, implants associated with periimplantitis can be clinically stable with only radiographic evidence of bone loss, or symptomatic: mobility of implant, purulent or sero-sanguinous
Surgical Complications in Dental Implantology
Fig. 4. (A) Immediate postoperative panoramic radiograph of symphyseal graft harvested to reconstruct buccal defect in tooth #19/20 site. (B) Resorption of graft; sharp edge or superior aspect of graft resulting in wound dehiscence and subsequent resorption of graft.
drainage, foul odor, gingival bleeding, or rarely, pain. In addition, surrounding tissues may appear edematous or tender on examination. On radiographs, there is loss of alveolar bone height; the degree will indicate presence or absence of mobility to the implant. Prevention of peri-implantitis is primarily on the patient’s shoulders to maintain excellent oral hygiene. The surgeon, however, needs to educate the patient on hygiene importance and procedure; further the surgeon and patient must work in concert with the general dentist/dental hygienist in maintaining placed implants and preventing periimplantitis. Furthermore, once the endosseous implants have been restored, it is the responsibility of the restorative dentist to ensure that the dental prosthesis is easily cleansable and does not create areas for plaque build-up around the implants. Endosseous implants developing peri-implantitis (clinical suppuration or bone loss radiographically) that are still immobile should be attended to quickly to prevent their failure. Strategies often are based on the degree of bone loss or probing depth. Minimal bone loss and probing depths of less than
4 mm usually require plaque and calculus removal, polishing of the implant crown, and increased oral hygiene visits annually. Mild bone loss and probing depths of 4 to 6 mm require, in addition to increased hygiene visits, chlorhexidine rinses daily or the application of chlorhexidine gels to the affected area. Applying citric acid directly to the exposed implant threads can be considered to detoxify the area. Typically, daily rinsing should be continued until improvement (decreased probing depths) is noted. If probing depths increase beyond 6 mm of significant bone loss (implant still stable), then in addition to hygiene and rinsing, systemic antibiotics focused on gram-negative coverage (metronidazole) is administered for 10 days. Once the any suppuration, edema, and/or infection has resolved, it is reasonable to consider guided tissue regenerative procedures with allogenic bone grafting to restore bone height around the implant.8 If the implant is restored, the restoration should be taken out of occlusion to minimize functional loads. Mobility of implants results in implant failure, and removal is required with possible bone grafting if desired (Fig. 5).
Fig. 5. (A) Panoramic radiograph at time of placement of implant. (B) Three months after placement greater than 50% bone loss.
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Aziz REFERENCES 1. Hassani AA, Aighamdi AS. Inferior alveolar nerve injury in implant dentistry: diagnosis, causes, prevention, and management. J Oral Implantol 2010;36:401–7. 2. Misch C, Resnick R. Mandibular neurosensory impairment following dental implant surgery. Management and protocol. Oral Health J 2012;12:1–12. 3. Steiner M, Ramp WK. Short term storage of freshly harvested bone. J Oral Maxillofac Surg 1988;46:868–71. 4. Whetzel TP, Sanders CJ. Arterial anatomy of the oral cavity: an analysis of vascular territories. Plast Reconstr Surg 1997;100:582–7.
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