**5. Bone harvesting from intraoral donor sites**

#### **5.1. The chin**

**•** Relation of augmentation and defect region (internal; inside the contour and external,

Anterior and posterior parts of the mandible and maxilla have different bone qualities; hence they have different regenerative capacities [7]. The length of the defect affects the degree of vascularization. In vertical defects with no sufficient width to accept implants, the augmenta‐ tion procedure becomes complicated because both dimensions require restoration [8]. It has been suggested that a wide bony defect base has greater capacity for bone regeneration compared to a narrow base defect [7]. The number of surrounding bony walls around the defect

Different classifications to describe alveolar ridge defects have been documented [9-11]. Seibert et al. classified the defects of the alveolar ridge based on dimension in which the resorption had occurred: horizontal defects (class I, 33%), vertical defects (class II, 3%) and the most

Some similar classifications were suggested by other investigators according to the morphol‐ ogy of the alveolar bone defects. A classification published by Wang and Al-Shammari, the defects were subdivided in: horizontal, vertical, and combined [12]. Each group was further classified based on the amount of the deficiency.Studer (1996) documented the first quantita‐ tive classification of alveolar defects based on predicting need to reconstruct deficiencies, with

**Figure 2.** A, Interdental partial edentulism. Class A: two-wall defect. The arrows show the defect walls. B, Free end

The Cologne classification of alveolar ridge defects uses orientation of the defect (horizontal, vertical, combined and sinus area) reconstruction needs associated with the defect (small: < 4 mm, medium: 4-8 mm large: > 8 mm) [8].Khojasteh et al. in 2013 in a literature review stressed the clinical importance of recipient site characteristics for vertical ridge augmentation con‐ cluded that information regarding the characteristics of the initial vertical defect is not comprehensively incorporated in most of the studies [8]. They proposed a classification with regard to the number of surrounding bony walls (A: Two-wall defects, B: One-wall defects, C:

**•** Defect base width and number of residual bony walls surrounding the defect

is mentioned in the literature as stabilization for the initial blood clot [8].

common variant mixed horizontal and vertical defects (class III, 56%) [10].

classes defined as < 3 mm, 3–6 mm and > 6 mm [8].

partial edentulism. Class B: one-wall defect (arrow).

outside the ridge contour)

516 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

Cortical or corticocancellous block graft in sizes up to 4 cm can be harvested from the man‐ dibular symphysis area intraorally (Figure 3). The mandibular symphysis as a donor site has been documented to provide sufficient bone to reconstruct alveolar ridge defects 4-6 mm in horizontal and up to 4 mm in vertical dimensions and can cover a span up to 3 teeth in length [13]. The available block graft may be harvested from this site is 10 mm (height) 15 mm (width), 6 mm (thickness), with an average volume of 860 cc [14]. The symphysis can provide over 50% larger graft volume in comparison to the lateral ramus region [15]. The typical symphysis corticocancellous bone graft consists of 65% cortical bone and 36% cancellous bone [14]. Because of slow resorption rate of chin grafts, it can also be used as an onlay graft for facial defects.

**Figure 3.** Block bone graft harvested from the mandibular symphysis

#### **5.2. Lateral ramus**

The mandibular lateral ramus or retro-molar region is advocated for corticocancellous bone harvesting with approximately 100% cortical composition (Figure 4).

**Figure 4.** Block bone graft harvested from mandibular lateral ramus area.

A buccal shelf block graft can provide sufficient bone to reconstruct alveolar defects 2-3 teeth in length. Horizontal and vertical defects up to 3 to 4 mm can be augmented from this donor site [16, 17]. The maximum dimensions of ramus cortical bone blocks are 4mm (thickness) 15 mm width and 35 mm in length depending on the regional anatomy. The clinical access, position of the inferior alveolar canal, molar teeth, and width of the posterior mandible are factors limiting the amount of possible graft that may be harvested [16, 17]. The morbidity of this region has been reported lower than the mandibular symphysis region [15].

#### **5.3. Maxillary tuberosity**

Among intra-oral donor sites, the maxillary tuberosity typically provides a smaller amount of bone (Figure 5).

**Figure 5.** Block bone graft harvested from the maxillary tuberosity.

This region is usually used for harvesting cancellous bone to fill defects and for sinus lifting procedures. Existence of the 3rd molar in this site decreases the available bone for harvesting. Other anatomical limitations for using this site include: the maxillary sinus, pterygoid plates and the greater palatine canal.

#### **5.4. Anterior palate**

**5.2. Lateral ramus**

**5.3. Maxillary tuberosity**

bone (Figure 5).

The mandibular lateral ramus or retro-molar region is advocated for corticocancellous bone

A buccal shelf block graft can provide sufficient bone to reconstruct alveolar defects 2-3 teeth in length. Horizontal and vertical defects up to 3 to 4 mm can be augmented from this donor site [16, 17]. The maximum dimensions of ramus cortical bone blocks are 4mm (thickness) 15 mm width and 35 mm in length depending on the regional anatomy. The clinical access, position of the inferior alveolar canal, molar teeth, and width of the posterior mandible are factors limiting the amount of possible graft that may be harvested [16, 17]. The morbidity of

Among intra-oral donor sites, the maxillary tuberosity typically provides a smaller amount of

this region has been reported lower than the mandibular symphysis region [15].

harvesting with approximately 100% cortical composition (Figure 4).

518 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

**Figure 4.** Block bone graft harvested from mandibular lateral ramus area.

**Figure 5.** Block bone graft harvested from the maxillary tuberosity.

This area is used as a donor site usually for anterior maxillary reconstruction, especially when an impacted canine is imbedded in this region (Figure 6).

**Figure 6.** A, palatal flap is retracted and the donor site for harvesting palatal bone graft is exposed. B, block bone graft harvested from the anterior palate.

The corticocancellous block, cancellous or crescent-shaped grafts can be harvested from this site. The average amount of bone in this area in dentate patients is 2 cc and 2.4 in edentulous patients [18].
