**3. Bone grafting drawbacks**

### **3.1. Preservation of the alveolar socket**

Socket preservation procedure serves to maintain the alveolar bone existing volume including height and width by delivering graft materials into the alveolar socket after extraction and to enhance new bone formation inside the socket. Various techniques and materials have been applied and so far they have shown favorable results. Complications may either be caused by surgical procedures or treatment planning. Excessive amounts of graft should be avoided. Graft materials should gently be compacted keeping adequate between its particles to allow revascularization and penetration of proteins and growth factors. Furthermore the flap design has to be considered regarding the augmentation site specially in critical sites such as esthetic zone. Park and Wang introduced the mucogingival pouch flap design to preserve the papil‐ la,improve graft retention and reduce exposure of the membrane. However in case that the interdental space is less than 6mm, the mucogingival pouch flap may threaten the overall blood supply of the flap caused by the vertical releasing incision. Thus wise treatment planning is needed to avoid possible complications. Disappearance and contamination of the grafts placed inside the dental socket may be expectable. Membranes used for GBR also strengthen the risk of exposure and infection. Froum evaluated the healing of sockets underwent preservation using hydroxyapatite and nonabsorbable inorganic bovine bone mineral covered by either ePTFE membrane or acellular dermal matrix allograft. Having not adequately covered the socket with soft tissue, 1 of 8 sockets covered by acellular dermal matrix and 6 of 8 sockets covered by ePTFE exhibited exposure of membranes which consequently led to early removal of the membranes because of potential infection. Reduction of facial facial keratinized tissue followed by primary closure itself can be considered as a complication. Though this can be avoided by wise treatment planning and allowing the socket to heal for 6 to 8 weeks in advance before grafting. Recently formed keratinized tissue growing over the dental socket will provide adequate coverage without giving away the facial width.

### **3.2. Guided bone regeneration or ridge augmentation**

Guided bone regeneration (GBR) was proved to be effective in regenerating new bone on alveolar ridges with atrophies both vertically and horizontally accompanied with membranes. Much the same as onlay bone graft which also acts as a space maintainer, GBR may serve similar complications related to the use of onlay grafts. Furthermore, GBR may also include the use of membrane and sometimes microscrews. Thus, complications that pertain to GBR may vary such as membrane exposure, microscrew exposure and infection. Critical inflam‐ matory reactions have also been recorded. The prevalence of flap sloughing associated with nonabsorbable membranes was high. Exposure of fixation screw or membrane may often lead to local inflammations accompanied with decreased new bone formation. There have been arguments over the significance of early membrane exposure on regenerative outcome of guided tissue regeneration and GBR operations. Several studies have reported that the responses were better when the membranes remained submerged while some other studies cast doubt on this issue.

#### **3.3. Monocortical onlay grafts**

spongiform encephalopathy transmission with bovine xenograft reckoned to be less than that

Thus, the risk of disease transmission from an allograft or xenograft is almost zero as long as the disinfection/sterilization protocols are followed by manufacturers. The world health organization affirmed that bone is classified as type IV (no transmission) for prion diseases. Therefore all currently available bone graft materials are secure and reliable concerning disease

Socket preservation procedure serves to maintain the alveolar bone existing volume including height and width by delivering graft materials into the alveolar socket after extraction and to enhance new bone formation inside the socket. Various techniques and materials have been applied and so far they have shown favorable results. Complications may either be caused by surgical procedures or treatment planning. Excessive amounts of graft should be avoided. Graft materials should gently be compacted keeping adequate between its particles to allow revascularization and penetration of proteins and growth factors. Furthermore the flap design has to be considered regarding the augmentation site specially in critical sites such as esthetic zone. Park and Wang introduced the mucogingival pouch flap design to preserve the papil‐ la,improve graft retention and reduce exposure of the membrane. However in case that the interdental space is less than 6mm, the mucogingival pouch flap may threaten the overall blood supply of the flap caused by the vertical releasing incision. Thus wise treatment planning is needed to avoid possible complications. Disappearance and contamination of the grafts placed inside the dental socket may be expectable. Membranes used for GBR also strengthen the risk of exposure and infection. Froum evaluated the healing of sockets underwent preservation using hydroxyapatite and nonabsorbable inorganic bovine bone mineral covered by either ePTFE membrane or acellular dermal matrix allograft. Having not adequately covered the socket with soft tissue, 1 of 8 sockets covered by acellular dermal matrix and 6 of 8 sockets covered by ePTFE exhibited exposure of membranes which consequently led to early removal of the membranes because of potential infection. Reduction of facial facial keratinized tissue followed by primary closure itself can be considered as a complication. Though this can be avoided by wise treatment planning and allowing the socket to heal for 6 to 8 weeks in advance before grafting. Recently formed keratinized tissue growing over the dental socket will provide

Guided bone regeneration (GBR) was proved to be effective in regenerating new bone on alveolar ridges with atrophies both vertically and horizontally accompanied with membranes. Much the same as onlay bone graft which also acts as a space maintainer, GBR may serve similar complications related to the use of onlay grafts. Furthermore, GBR may also include

of being hit by lightning.

transmission potential.

**3. Bone grafting drawbacks**

**3.1. Preservation of the alveolar socket**

570 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

adequate coverage without giving away the facial width.

**3.2. Guided bone regeneration or ridge augmentation**

Complications with regard to ridge augmentation using the onlay bone grafts mainly include infection, opening of the incision line, bone fracture, Nerve malfunction, rupture of mucosa over the implant, loss of portion of the bone graft, dehiscence of the wound and graft move‐ ment. While the most common complication is the incision line opening that leads to contam‐ ination of graft, delay in vascularization and loss of graft material, the most deleterious outcome on survival of implants in the augmentation site is related to wound dehiscence.The prevalence of unintentional skin/mucosa perforation was 5.2% for mandible as augmentation site with onlay bone graft and the incidence for infection occurred in 1 of the 11 patients(9.1%) that resulted in partial loss of graft. Infection of the graft can be caused by endogenous bacteria, deprived aseptic surgical technique or inadequacy of primary closure. Antibiotics were used to prevent bacterial infection and to enhance collagen formation. However it was found that tetracycline arrests the bone formation chelating calcium at the graft. Thus, other antibiotics such as penicillin or clindamycin have been suggested.

#### **3.4. Sinus lifting**

Sinus lifting procedure is performed when there is insufficient height for implant placement by lifting the Schneiderian membrane apically with bone grafting materials at the posterior maxillary edentulous ridge. Perforation of the Schneiderian membrane, opening of the incision line, sinusitis, formation of cysts, misplacement of graft particles and mucosal dehiscence are complications with regard to sinus lift procedures. Perforation of sinus membrane can either be pre existing or be caused by tearing during the operation and its prevalence has been reported ranging from 10% to 34%. Sinus perforation can be managed using an absorbable membrane. Pathologic conditions affiliated with paranasal sinuses are very prevalent. More than 31 million people around the world suffer from sinusitis each year. The infection of sinus may potentially cause critical complications such as sinusitis, orbital cellulitis, meningitis, cavernous sinus thrombosis and osteomyelitis. The incidence of acute sinusitis is reported to be around 3%. Moreover sinusitis may result in more complicated situations. Loss of bone graft particles and sequestrae is not prevalent but possible. Failure of Branemark implants at the grafted sites after a mean period of 32 months was 6.7%. A comprehensive pre operative assessment is important to detect any existing pathologic condition in maxillary sinus. This surely can reduce the risk of mucus and bacterial infection in the surgical field and compro‐ mising bone healing. Moreover due to vicinity of the maxillary sinus to vital structures such as brain, cavernous sinus, etc, post-operative complications can be critical and life threatening.
