**1.1 Classification of defect morphology**

Classification of the defect morphology is as follows [5]:


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**Figure 3.**

*Alveolar Ridge Augmentation Techniques in Implant Dentistry*

*DOI: http://dx.doi.org/10.5772/intechopen.94285*

**2. Guided bone regeneration**

*clinical scenario may not always be straight-forward.*

augmentation of [8]:

**Figure 2.**

Guided bone regeneration (GBR) is a procedure utilizing barrier membranes

to create adequate space for new bone formation. Use of barrier membranes avoids soft tissue collapse and non-osteogenic cell migration into the bone defect [8]. It also facilitates an ideal environment for bone formation by providing space maintenance, stabilization of graft materials and prevention of soft tissue ingrowth (**Figure 3**) [9]. Guided bone regeneration can is indicated for the

*Schematic representation of a five-walled bone defect. A reduce in the number of any walls renders corresponding wall-numbered bone defect. Translation of this wall-wall-number defect classification to the* 

*Guided bone regeneration (GBR) procedure create and maintain a space via a semi-permiable barrier membrane which the blood cloth will occupy and allow the proliferation of the bone-producing cells.*

*Alveolar Ridge Augmentation Techniques in Implant Dentistry DOI: http://dx.doi.org/10.5772/intechopen.94285*

#### **Figure 2.**

*Oral and Maxillofacial Surgery*

A large variety of bone augmentation techniques can be applied in the presence of bone defects. Guided bone regeneration, ridge splitting, distraction osteogenesis, maxillary sinus lifting and autogenous onlay block bone grafting are main techniques which have successful outcomes in reconstruction of bone defects. This chapter

Defect morphology plays a critical role when choosing the type of augmentation procedure to perform. Number of surrounding bony walls are important when an augmentation is planned, because vascularization and healing properties are provided by these walls to the augmentation site. Therefore, defects with less amount

• *Thick five bony wall defect* is usually a tooth extraction socket. This type of defects have most of the important keys for a predictable bone regeneration process. Defect size is small, therefore regeneration by particulate bone grafts is possible. Surrounding five bony walls provide space maintenance and stabilize the blood clot along with the graft particulates. Torn blood vessels post-extraction accelerates the regeneration by releasing growth factors to the site. Augmentation of five bony wall defect is preservation of the residual alveolar ridge. Any resorbable graft material can be used in this type of bone defect depending on the desired healing period until the implant

• Regeneration of *four to five bony wall defect* is impaired since vascularization from bony walls is reduced and partially replaced by soft tissue vascularization. When the buccal wall is missing post-extraction, space maintenance is no longer possible by the socket itself. Soft tissue tends to grow into the socket, therefore use of a barrier membrane along with particulate bone grafts is necessary to regain the ideal volume and contour of bone. Any resorbable bone graft material can be preferred in this case. When one of the lateral walls is missing following extraction, repair of this wall can be faciliated with socket preservation procedure at the time of extraction. Otherwise, during the healing period residual bone resorption may occur to an extend that requires

• Treatment of *two to three bony wall defect* is similar to the treatment of four bony wall defect. Since the defect size is bigger in this type, use of autogenous bone grafts is required for their osteogenic properties. It's recommended to combine autografts with other resorbable graft materials to avoid rapid resorption and provide enough space while new bone regenerates. Resorbable barrier membranes can be supported with tenting screws or titanium reinforced non-resorbable membranes can be preferred in this type of defects as

it requires more stability and space maintenance for longer periods.

• *One bony wall defect* is the most challenging defect type. Vascularization and regeneration potential of this defect is very low. Bone volume that needs to be regenerated is at high levels. For predictable outcomes, it's recommended to fixate onlay bone blocks to the host bone in this type of severe bone atrophies. There are studies reporting better outcomes with utilizing both onlay bone block grafting and guided bone regeneration at the same time [7] (**Figure 2**).

reviews alveolar ridge augmentation techniques in brief [1–4].

of remaining bony walls are considered to be complex [5, 6].

Classification of the defect morphology is as follows [5]:

**1.1 Classification of defect morphology**

further augmentation procedures.

placement.

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*Schematic representation of a five-walled bone defect. A reduce in the number of any walls renders corresponding wall-numbered bone defect. Translation of this wall-wall-number defect classification to the clinical scenario may not always be straight-forward.*

#### **2. Guided bone regeneration**

Guided bone regeneration (GBR) is a procedure utilizing barrier membranes to create adequate space for new bone formation. Use of barrier membranes avoids soft tissue collapse and non-osteogenic cell migration into the bone defect [8]. It also facilitates an ideal environment for bone formation by providing space maintenance, stabilization of graft materials and prevention of soft tissue ingrowth (**Figure 3**) [9]. Guided bone regeneration can is indicated for the augmentation of [8]:

#### **Figure 3.**

*Guided bone regeneration (GBR) procedure create and maintain a space via a semi-permiable barrier membrane which the blood cloth will occupy and allow the proliferation of the bone-producing cells.*


Over a decade, autogenous bone block grafting was the standard procedure in augmentation of bone defects. Due to its' invasive harvesting technique, morbidity at the donor site and limited availability, new techniques are developed. With rapid progress in biomaterials, GBR became one of the safest and most common techniques as it's less invasive and causes less discomfort post-operatively. Particulate grafts used in the procedure can easily be adapted into complex defect geometries [2, 5]. Urban et al. demonstrated a new bone formation of 5.45 mm vertically as a mean value when GBR protocol is performed utilizing xenograft and autogenous particulate graft mix with d-PTFE membranes [10]. Still, GBR has its own technique-sensitive challenges and is need to be practiced meticulously.

To achieve successful and repetitive outcomes, guided bone regeneration has 4 key principles: P-A-S-S [2, 8].

*Primary wound closure* is an important key factor for an optimal healing and success. In the augmentation sites, biomaterials and membranes increase the tissue volume so it becomes harder to close the wound without tension.

To provide a tension-free closure, incision design must be considered carefully.


*Angiogenesis* provide nutrients and oxygen to the augmentation site and enhances healing process in this way. To ensure an ideal angiogenesis, patients must be examined thoroughly in terms of systemic diseases which affect healing mechanisms such as diabetes mellitus and osteoporosis. In these cases, an internist or an endocrinologist may be consulted if necessary. Any uncontrolled systemic disease should be taken into consideration as a contraindication. Smoking habits also reduce vascularization and proper blood supply in the surgical site. Measures like using local anesthetics without vasoconstrictors or encouraging patients to regulate their smoking cycles can be taken.

*Space creation and maintenance* prevents soft tissue collapse to the surgical site thus osteogenic cells can proliferate and gradually form bone tissue. Biomaterials and particulate grafts along with barrier membranes can be used for this process. While barrier membranes prevent migration of soft tissue cells to the regeneration space, bone grafts and biomaterials provide structural strength. Depending on the type of barrier membrane in use, tenting poles can be used to provide additional strength.

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*Alveolar Ridge Augmentation Techniques in Implant Dentistry*

*Stability of wound clot* is essential for optimal healing since the blood clot provides lots of growth factors to the surgical site. Primary wound closure and barrier membranes, acting as a roof to the regeneration site, contribute in stabilizing the blood clot. Recent studies show that barrier membranes need to be fixated with pins or screws to provide enough stability also to the graft materials, otherwise up to

A barrier membrane is an essential component in guided bone regeneration procedures. Various membranes with different features are available on the market [12]. Barrier membranes should fulfill some basic requirements to be safely utilized

• *Biocompability:* Host tissue and membrane should be biologically compatible

• *Space-maintenance:* Barrier membrane must avoid any collapse and maintain

• *Barrier function:* Preventing soft tissue cells from migrating to regeneration site

• *Stability:* Membranes must have mechanical strength and proper physical properties which protects the regeneration site during healing period.

• *Degradability:* Ideally a membrane should degrade at a time rate matching the

There are two main groups of membranes: resorbable and non-resorbable [7].

Using resorbable membranes eliminates the second surgical intervention for membrane removal after healing and in this way decreases morbidity. Less complications occur with resorbable membranes compared to the non-resorbable ones. These membranes can easily be manipulated and adapted to the defect since they don't have any reinforcements with high elastic modulus. On the other hand, when compared to non-resorbable membranes they are more prone to collapse which lowers the maintained space. Bone graft substitutes and additional tools like tenting poles can be used along with resorbable membranes to increase stability. One major drawback of these membranes is varied and sometimes unpredictable resorption

Resorbable membranes can be classified as natural and synthetic (**Figure 4**).

• *Non-cross-linking resorbable collagen membranes* are made of native collagen, have high levels of biocompability. They well-integrate into tissues and rapidly become vascularized. However, non-cross-linking resorbable membranes may resorp earlier than the required time for regeneration and lose their barrier functions. Cellular activity of host bone, membrane properties and possible exposures affect the biodegradation time. If any exposure occurs within the membrane, soft tissue spontaneously covers the exposed area in most cases. Bone grafts may resorp causing a decrease in the expected bone formation, though [3, 13].

%40 of graft content is lost until the patient leaves the clinic [11, 12].

*DOI: http://dx.doi.org/10.5772/intechopen.94285*

**2.1 Barrier membranes**

in dental applications [3].

regeneration period.

*2.1.1 Resorbable membranes*

avoiding any foreign body reactions.

space during the regeneration period.

is an essential feature for membranes.

rates which directly affect new bone formation [13–15].

*Stability of wound clot* is essential for optimal healing since the blood clot provides lots of growth factors to the surgical site. Primary wound closure and barrier membranes, acting as a roof to the regeneration site, contribute in stabilizing the blood clot. Recent studies show that barrier membranes need to be fixated with pins or screws to provide enough stability also to the graft materials, otherwise up to %40 of graft content is lost until the patient leaves the clinic [11, 12].
