**8. Reconstruction techniques**

Different reconstruction techniques have been known and well documented for bony defects in the oral and maxillofacial area. Distraction osteogenesis and guided bone regeneration techniques, grafting procedures and especially autogenous bone grafting still are the treat‐ ments of choice in most alveolar bony defects. Soft tissue consideration and management should be borne in mind for successful stable results.

#### **8.1. Bone grafting**

"Any implanted material that promotes bone healing" is defined as a bone graft [24]. Ideally it must be: osteoconductive, osteoinductive and osteogenic.

**An osteoconductive capacity** means allowing or directing the new bone to form within the material structure.

**An osteoinductive capacity** describes supplying recruitment and/or differentiation factors for bone-forming cells by the grafting material.

**An osteogenic graft material** provides induced or inducible bone-forming cells.

Bone grafts are used not only for a defect facilitating healing but also for contour augmenta‐ tions. For this purpose more attention is directed towards the amount and rate of graft resorption. Graft incorporation is proportional to amount of graft resistance to resorption [24].

Bone grafts can be classified as:

**Autografts** (transferring bone in one human(,

**Allografts** (transferring inter-humans), and

**Xenografts** (transferring from other species, synthetic materials and any combination of them).

Autografts can be cancellous, cortical, corticocancellous, vascularized bone or aspirated bone marrow. The main advantage of autogenous bone is retention of at least some osteogenic cells without triggering the immune system. On the other hand donor site morbidity and limited amount are basic disadvantages. Ideally, the bone graft should be incorporated into the recipient bed; the space that the bone graft occupies should finally become viable bone with physiological remodeling mechanisms. Many factors are involved in the incorporation process namely the graft type, graft bed (recipient site), and interface in between. Graft related factors including the type of graft, porosity and mechanism of incorporation. Recipient site viability and vascularity are very important in any autogenous grafting procedures. Graft incorporation has been summarized by Bauer and Muschler in five steps [24[


**7.4. Rib graft**

nowadays [27].

**8.1. Bone grafting**

material structure.

overgrowth of the graft [27, 28].

**8. Reconstruction techniques**

522 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

should be borne in mind for successful stable results.

bone-forming cells by the grafting material.

**Autografts** (transferring bone in one human(,

**Allografts** (transferring inter-humans), and

Bone grafts can be classified as:

it must be: osteoconductive, osteoinductive and osteogenic.

Free rib bone was one of the first autogenous bone grafts used for reconstruction of mandibular defects. Osseous or osseochondral grafts can be harvested from fifth to seventh ribs. Although costochondral grafts remain popular for the treatment of mandibular ramus and condylar defects, the quality and quantity of rib bone make it less popular for jaw defect reconstruction

**Complications.** Postoperative chest wall pain, pleural injury leading to pneumothorax, and

Different reconstruction techniques have been known and well documented for bony defects in the oral and maxillofacial area. Distraction osteogenesis and guided bone regeneration techniques, grafting procedures and especially autogenous bone grafting still are the treat‐ ments of choice in most alveolar bony defects. Soft tissue consideration and management

"Any implanted material that promotes bone healing" is defined as a bone graft [24]. Ideally

**An osteoconductive capacity** means allowing or directing the new bone to form within the

**An osteoinductive capacity** describes supplying recruitment and/or differentiation factors for

Bone grafts are used not only for a defect facilitating healing but also for contour augmenta‐ tions. For this purpose more attention is directed towards the amount and rate of graft resorption. Graft incorporation is proportional to amount of graft resistance to resorption [24].

**Xenografts** (transferring from other species, synthetic materials and any combination of them).

Autografts can be cancellous, cortical, corticocancellous, vascularized bone or aspirated bone marrow. The main advantage of autogenous bone is retention of at least some osteogenic cells without triggering the immune system. On the other hand donor site morbidity and limited amount are basic disadvantages. Ideally, the bone graft should be incorporated into the

**An osteogenic graft material** provides induced or inducible bone-forming cells.


Graft stabilization is other critical issue in bone graft incorporation and vascularization. Instability leads to bone resorption and infection. Cancellous bone grafts can be packed in defect cavities. In these cases more graft material transfer, leads to more vital cells and increase in osteogenesis. Cortical or corticocancellous block grafts should be stabilized using fixation devices.

#### **8.2. Bone Grafting with intra oral donor sites (localized bone augmentation)**

#### *8.2.1. Symphysis block harvesting*

There are three basic approaches to access the mandibular symphysis for bone graft harvesting: 1) sulcular, 2) attached gingiva, or 3) vestibular. The advantages of sulcular and attached gingiva approaches are reductions in wound dehiscence and bleeding compared to the vestibular approach. Use of the sulcular approach is not advocated in pre-existing periodontal diseases or crowns. The vestibular approach is done through the mucosa 5 to 10 mm below the mucogingival junction; first by partial thickness dissection apically for 3mm to maintain 3mm of periosteum and mentalis muscle fibers on the bone side, which will be used to reattach the muscle fiber [29]. Below this level a full thickness incision is made and full thickness flap reflection is used. Careful attention must be paid to prevent trans-section of the mental nerve at the distal extent of the incision bilaterally (Figure 10).

It is suggested that at least 5 mm bone is maintain below the teeth apices, inferior border and bilaterally anterior to mental foramina. When a large bone block is needed, the anterior most portion of the symphysis the mental protuberance must be retained. If it is necessary to harvest two graft blocks from each side, leaving a 3mm midline connection to maintain support for the chin profile is necessary [30].The block graft can be osteotomized by a rotary bur, recipro‐ cating saw, or piezo instrument. Using rotary burs has disadvantages of losing some amount of bone in comparison to two other methods. Osteotomies should enter the inter-cortical layer, giving close attention not violate the lingual cortex. A fine osteotome or chisel can be used to

**Figure 10.** Full mucoperiosteal flap retracted to expose the donor site for harvesting symphyseal bone. Two osteotomy sites are determined on both sides and 3mm bone is maintained in between to support the chin profile.

reflect block bone graft from its bed. After block removal a hemostatic agent can be used in the donor site. Some clinicians prefer to fill the donor site with Freeze Dried Bone Allograft (FDBA), especially when a large block has been harvested. In the vestibular approach, when closing, a resorbable suture is first used to attach the mentalis muscle to the 3mm periosteal muscle layer left on the bone side.

#### *8.2.2. Lateral ramus block harvesting*

The approach to harvest bone graft from the lateral ramus can proceed two different ways: 1) Vestibular or 2) Sulcular. The vestibular approach has access through the area through vestibular incision on external oblique ridge. Advantage of this approach is lack of disturbing the periodontium of the adjacent teeth. The indication of sulcular approach is when recipient site is located nearby. The distal extent of the incision should not be more than occlusal plane to minimize the risk of facial nerve damage, bleeding and exposing buccal fat. Osteotomy is suggested to be performed in a defined sequence; superior cut, then anterior, then posterior and finally inferior cut (Figure 11).

The superior cut length and thickness is important. This cut is usually made approximately 4 mm medial to the external oblique ridge but can be performed up to 6 mm depending on the regional anatomy. It may be extended anteriorly to the distal area of the first molar, depending on the anatomy. The anterior and posterior vertical cuts are made in parallel to the predicted length and width of the bone graft block, and are limited by anatomic position of the man‐ dibular canal, which determines the harvesting block width. Complete cortical penetration of inferior osteotomy cut is avoided due to its proximity to the mandibular canal in many cases. An osteotome or a chisel can be used to remove the bone graft from its bed avoiding penetrating excessively to damage mandibular canal. Closing the incision usually is done without applying any graft or hemostatic agent.

**Figure 11. Intraoral approach to harvest the lateral ramus bone block. The .osteotomy line of the superior cut is seen Figure 11.** Intraoral approach to harvest the lateral ramus bone block. The osteotomy line of the superior cut is seen.

#### **8.3. Anterior iliac crest bone grafting** The superior cut length and thickness is important. This cut is usually made

reflect block bone graft from its bed. After block removal a hemostatic agent can be used in the donor site. Some clinicians prefer to fill the donor site with Freeze Dried Bone Allograft (FDBA), especially when a large block has been harvested. In the vestibular approach, when closing, a resorbable suture is first used to attach the mentalis muscle to the 3mm periosteal

**Figure 10.** Full mucoperiosteal flap retracted to expose the donor site for harvesting symphyseal bone. Two osteotomy

sites are determined on both sides and 3mm bone is maintained in between to support the chin profile.

The approach to harvest bone graft from the lateral ramus can proceed two different ways: 1) Vestibular or 2) Sulcular. The vestibular approach has access through the area through vestibular incision on external oblique ridge. Advantage of this approach is lack of disturbing the periodontium of the adjacent teeth. The indication of sulcular approach is when recipient site is located nearby. The distal extent of the incision should not be more than occlusal plane to minimize the risk of facial nerve damage, bleeding and exposing buccal fat. Osteotomy is suggested to be performed in a defined sequence; superior cut, then anterior, then posterior

The superior cut length and thickness is important. This cut is usually made approximately 4 mm medial to the external oblique ridge but can be performed up to 6 mm depending on the regional anatomy. It may be extended anteriorly to the distal area of the first molar, depending on the anatomy. The anterior and posterior vertical cuts are made in parallel to the predicted length and width of the bone graft block, and are limited by anatomic position of the man‐ dibular canal, which determines the harvesting block width. Complete cortical penetration of inferior osteotomy cut is avoided due to its proximity to the mandibular canal in many cases. An osteotome or a chisel can be used to remove the bone graft from its bed avoiding penetrating excessively to damage mandibular canal. Closing the incision usually is done without applying

muscle layer left on the bone side.

524 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

*8.2.2. Lateral ramus block harvesting*

and finally inferior cut (Figure 11).

any graft or hemostatic agent.

Anterior iliac crest bone grafts are common used grafts not only in maxillofacial surgery but also in orthopedic surgery. The iliac crest is almost subcutaneous and cortical or corticocan‐ cellous grafts in different shapes and size can be taken from this region simply and safety. The *anterior superior iliac spine (ASIS)*, is easily palpable which is located in the most anterior and superior portion of the crest. Posteriorly along the crest of the ilium in the widest portion is the iliac tubercle. The incision starts 2 cm posterior to ASIS and continues up to 8 cm along the crest. The neural branches, which are in risk of damage, are iliohypogastric, subcostal branches and lateral femoral cutaneous nerves. Retracting the skin medially and avoiding extending the incision posteriorly are suggested to decrease this risk. Dissecting laterally and violating iliotibial fascia is not recommended. Harvesting bone from iliac crest can be performed via different approaches including using a trephine device, monocortically and bicortically with different techniques (Figure 12). approximately 4 mm medial to the external oblique ridge but can be performed up to 6 mm depending on the regional anatomy. It may be extended anteriorly to the distal area of the first molar, depending on the anatomy. The anterior and posterior vertical cuts are made in parallel to the predicted length and width of the bone graft block, and are limited by anatomic position of the mandibular canal, which determines the harvesting block width. Complete cortical penetration of inferior osteotomy cut is avoided due to its proximity to the mandibular canal in many cases. An osteotome or a chisel can be used to remove the bone graft from its bed

Usually monocortical bone blocks are harvested from the medial surface with osteotomes or a saw. In young ages, the border portion of the iliac crest consists of chondral struc‐ ture which should be bypassed in the harvesting procedure. Closing the donor site is done in three layers, and a vacuum drain usually is placed. Minor complications of this bone graft harvesting included superficial infections, superficial seromas, and minor hemato‐ avoiding penetrating excessively to damage mandibular canal. Closing the .incision usually is done without applying any graft or hemostatic agent **Anterior iliac crest bone grafting** Anterior iliac crest bone grafts are common used grafts not only in

maxillofacial surgery but also in orthopedic surgery. The iliac crest is almost subcutaneous and cortical or corticocancellous grafts in different shapes and size can be taken from this region simply and safety. The *anterior superior iliac spine (ASIS)*, is easily palpable which is located in the most anterior and superior portion of the crest. Posteriorly along the crest of the ilium in the widest portion is the iliac tubercle. The incision starts 2 cm posterior to ASIS and continues up to 8 cm along the crest. The neural

**Figure 12.** Iliac bone graft harvesting procedure.

mas. Major complications are herniation of abdominal contents, vascular injuries, deep infections at the donor site, neurologic injuries, deep hematoma formation requiring surgical drainage, and iliac fractures [31].

#### **8.4. Placing the bone graft into the recipient site**

A moist environment with saline is suggested as a reservoir for the autogenous bone graft. Cortical or corticocancellous block grafts can be adjusted for recipient site with burs, saws or discs. The block should be prepared so that when placed in the recipient site it does not rock and fits snuggly and is in intimate contact with the underlying host bone bed. Fixation of the block graft is a principle issue. Screws and plates are devices, which can be used to achieve sufficient stability. Applying two screws is recommended and using the lag screw technique is suggested. The recipient bed and block graft may be penetrated to facilitate vascular ingrowths. Applying particulate bone graft around the bone block is usually advocated to maintain space for more osteogenesis. The graft structure is then covered with a barrier membrane to prevent soft tissue ingrowth into the integrating new bone especially when particulate materials are added. Tension free closure of the grafted site is critical to success.

#### **8.5. Anatomic repositioning**

#### *8.5.1. Distraction osteogenesis*

Distraction osteogenesis (DO) is a contemporary method that has been used in oral and maxillofacial defects. DO is a method to generate new bone by gradual separation of bone segments. In this procedure a distractor device is placed on two sides of an osteotomy site (Figure 13).

After a latency period the device is gradually activated and makes a gap between two bone segments. The new immature bone is generated between these two segments in the created gap. Then the device will not be activated for a period to give the new bone a time to mineralize

mas. Major complications are herniation of abdominal contents, vascular injuries, deep infections at the donor site, neurologic injuries, deep hematoma formation requiring surgical

A moist environment with saline is suggested as a reservoir for the autogenous bone graft. Cortical or corticocancellous block grafts can be adjusted for recipient site with burs, saws or discs. The block should be prepared so that when placed in the recipient site it does not rock and fits snuggly and is in intimate contact with the underlying host bone bed. Fixation of the block graft is a principle issue. Screws and plates are devices, which can be used to achieve sufficient stability. Applying two screws is recommended and using the lag screw technique is suggested. The recipient bed and block graft may be penetrated to facilitate vascular ingrowths. Applying particulate bone graft around the bone block is usually advocated to maintain space for more osteogenesis. The graft structure is then covered with a barrier membrane to prevent soft tissue ingrowth into the integrating new bone especially when particulate materials are added. Tension free closure of the grafted site is critical to success.

Distraction osteogenesis (DO) is a contemporary method that has been used in oral and maxillofacial defects. DO is a method to generate new bone by gradual separation of bone segments. In this procedure a distractor device is placed on two sides of an osteotomy site

After a latency period the device is gradually activated and makes a gap between two bone segments. The new immature bone is generated between these two segments in the created gap. Then the device will not be activated for a period to give the new bone a time to mineralize

drainage, and iliac fractures [31].

**Figure 12.** Iliac bone graft harvesting procedure.

526 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

**8.5. Anatomic repositioning**

*8.5.1. Distraction osteogenesis*

(Figure 13).

**8.4. Placing the bone graft into the recipient site**

**Figure 13.** A. Patient with premaxillary deficiency. B. The patient has lost his anterior incisal teeth due to an anterior maxillary defect. C. Intra-oral view of the premaxilla defect. D. DO device is inserted in the surgery phase.

and turn into mature bone. This is called the consolidation phase and is usually twice the activation period. After the consolidation period the device is removed. During the activation period the surrounding soft tissue grows simultaneously with the bone formation (Figure 14). This is why the DO is also called distraction histogenesis. DO devices are divided into two groups of intraoral and extraoral types each of which have certain indications.

**Indications.** DO was generally used in orthopedics years before being used in maxillofacial surgery. The most popular indication of DO is in hemifacial or hemimandibular microsomia. Actually DO was used in a case of hemicraniofacial microsomia successfully for the first time by McCarthy et al. in 1992 [32]. The most important indication of DO is in syndromes associated with congenital anomalies like cerebral palsy, hemifacial microsomia, Treacher–Collins syndrome, Pierre–Robin sequence, Nager syndrome and others. Investigations have shown the successful results of DO in such cases [33].

**DO in vertical dimension** is another important indication. Although new methods of bone grafting like fibular microvascular graft have been broadly used in these defects sometimes their use is restricted by the large size of the defect. In these large defects DO is a better technique to regenerate new bone and reconstruct the defect [34]. Sometimes the combination of microvascularized grafts with DO procedure is an ideal technique to reconstruct large defects especially defects caused by resection of pathologic lesions [7].

**Figure 14.** Inserted DO device is shown to generate new bone for reconstruction of the maxilla. The distractor device has been activated for months. The alveolar bone height has increased.

**DO in transverse dimension** is an interesting method being used in patients with arch constriction or an alveolar cleft. Reviews of the clinical studies about the use of DO in maxillary hypoplasia in patients with cleft lip and palate have shown the benefits of this technique as an alternative to orthognathic surgeries [35]. The important advantage of DO in these patients is unchanged or better velopharyngeal function. This method can be used in the mixed dentition period which is an advantage of this procedure comparing to orthognathic surgery procedures.

DO has been recently used in patients with midface hypoplasia in craniosynostosis like Crouzon, Apert, and Pfeiffer syndromes. Several investigations have evaluated this technique and compared it to LeFort III osteotomy [36, 37]. Although LeFort III osteotomy has been widely used to correct the maxillary retrusion, it is not possible to advance the midface a large amount. Lefort III-DO technique has been suggested in patients with great discrepancy; however trials have shown higher relapse of this method compared to the usual LeFort III osteotomy procedure. The advantage of LeFort III-DO technique is the lower risk for severe complications like cerebrospinal fluid leakage, meningitis, and infection.

**Advantages.**Simultaneous distraction of the soft tissue is a great advantage of this technique. The quality or quantity of the soft tissue bed makes the results of bone grafting unpredictable and reduces the success of the bone graft. In most cases DO obviates the need for bone grafting in the future. Morbidity of a donor site is also eliminated. The process of inserting and removing the device is less extensive as well.

**Disadvantages.**DO is a technique sensitive procedure and should be performed by an expert surgeon. The quality of the device is an important factor in success rate of the DO results. Loosening of the screws and displacement of the device may occur in some cases. DO proce‐ dures consist of two operations: one for insertion of the device and a second surgery to remove it. Sometimes a third surgery is needed in the future to achieve the perfect outcome especially when DO has been performed in a young patient. Unpredictable outcomes or malocclusion are inadvertent results. Motor and sensory nerve dysfunction is an untoward complication of DO. This complication is especially seen in DO of the mandible which may lead to permanent or transient weakness of marginal branch of facial nerve or hypoesthesia of inferior alveolar nerve. Scar formation and infection should be considered a more usual complication of DO.

#### **8.6. Nerve repositioning**

**DO in transverse dimension** is an interesting method being used in patients with arch constriction or an alveolar cleft. Reviews of the clinical studies about the use of DO in maxillary hypoplasia in patients with cleft lip and palate have shown the benefits of this technique as an alternative to orthognathic surgeries [35]. The important advantage of DO in these patients is unchanged or better velopharyngeal function. This method can be used in the mixed dentition period which is an advantage of this procedure comparing to orthognathic surgery procedures.

**Figure 14.** Inserted DO device is shown to generate new bone for reconstruction of the maxilla. The distractor device

DO has been recently used in patients with midface hypoplasia in craniosynostosis like Crouzon, Apert, and Pfeiffer syndromes. Several investigations have evaluated this technique and compared it to LeFort III osteotomy [36, 37]. Although LeFort III osteotomy has been widely used to correct the maxillary retrusion, it is not possible to advance the midface a large amount. Lefort III-DO technique has been suggested in patients with great discrepancy; however trials have shown higher relapse of this method compared to the usual LeFort III osteotomy procedure. The advantage of LeFort III-DO technique is the lower risk for severe

**Advantages.**Simultaneous distraction of the soft tissue is a great advantage of this technique. The quality or quantity of the soft tissue bed makes the results of bone grafting unpredictable and reduces the success of the bone graft. In most cases DO obviates the need for bone grafting in the future. Morbidity of a donor site is also eliminated. The process of inserting and

**Disadvantages.**DO is a technique sensitive procedure and should be performed by an expert surgeon. The quality of the device is an important factor in success rate of the DO results. Loosening of the screws and displacement of the device may occur in some cases. DO proce‐ dures consist of two operations: one for insertion of the device and a second surgery to remove it. Sometimes a third surgery is needed in the future to achieve the perfect outcome especially

complications like cerebrospinal fluid leakage, meningitis, and infection.

removing the device is less extensive as well.

has been activated for months. The alveolar bone height has increased.

528 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

Rehabilitation of edentulous patients is often complicated and requires special consideration. In edentulous patients with atrophic bone above the mandibular canal is insufficient; reposi‐ tioning the inferior alveolar nerve (IAN) is a treatment option. This treatment is done if the overall bone height is enough to place implant fixtures, but the IAN interferes with this procedure. Repositioning of IAN is done to move the nerve from the canal placing it in a new position (outside the bone).

**Nerve lateralization** is a procedure in which the IAN is exposed and retracted laterally while the surgeon is inserting the fixtures. Then the nerve is left to fall back against the inserted fixtures or the lateral cortex. In nerve transposition technique the IAN, mental nerve and incisive nerve are exposed by corticotomy of the bone surrounding the mental foramen. Then the IAN is transected from its junction with the incisive nerve. In this way the nerve is freed and its retraction is much easier. The IAN is replaced posteriorly after cutting the incisive nerve. The surgeon is able to install the implant fixture after distalization of the IAN (Figure 15).

**Figure 15.** A, Nerve lateralization in an atrophic mandible to eliminate the nerve interfering with implant surgery. B, The IAN is transposed from the mandibular canal to make space for installation the implants. C, Simultaneous implant installation is also possible in this technique.

**Indications**.The actual indication of IAN transposition or lateralization is in atrophic posterior mandible where remaining bone above the mandibular canal is less than 10 mm [38,39]. There is no actual contraindication of IAN transposition reported in the literature.

**Advantages.** The risk of damage to IAN during the installation of fixtures is reduced by retracting and repositioning the nerve. The surgeon is able to use a longer fixture which may engage the inferior cortex of the mandible. The fixtures have more stability due to their bicortical insertion. This procedure is performed simultaneously with implant fixture instal‐ lation with or without bone grafting.

**Disadvantages.** The risk of damage to the IAN is a prominent disadvantage of nerve trans‐ positioning; Traction on the nerve usually causes temporary sensory loss [40]. Mandibular fracture, implant loss, hemorrhage, and osteomyelitis are other possible complications in long implant installation, associated with the transposition and lateralization of the IAN [38, 41, 42].
