**2. Chin modification**

The creation or restoration of an esthetically pleasing facial contour can encompass many surgical approaches. Several surgical techniques are available for correcting and giving harmony to the lower third of the face.[1] In this respect, some well-known techniques seek to correct the shape and size of the chin using different kinds of chin implants or osteotomies in an effort to move it and change its spatial location, thus determining a new facial contour.

#### **2.1. Augmentation genioplasty**

Genioplasty (anterior horizontal mandibular osteotomy) means a plastic procedure on the chin that involves both bony components (ie, anterior portion of the base of the mandible) and the soft tissue component.The procedure can be performed either alone or as an adjunct to other orthognathic and facial plastic surgeries. Either direct osteoplasty and soft tissue correction or implantation of an alloplastic material/cartilage/bone has been recommended for genioplasty. Since 1942, with first sliding advancement genioplasty that was described by Hofer, various genioplasty techniques with various indications, advantages, and disadvantages have been developed for correction of microgenia and macrogenia. In recent chapter we did not focused on augmentation genioplasty techniques.The readers can update their knowledge by review‐ ing the other chapters or books.

#### **2.2. Reduction genioplasty**

In the event of anterior mandibular bony excess different surgical approaches can be used. Each have their own limitations and disadvantages. For instance simple burring down removal of bony excess from anterior mandible through an intraoperative approach will usually result in an abnormal appearance and is not the best choice of treatment.

Reduction genioplasty surgical procedure results in narrowing or shortening of the chin. However, the literature lacks data about the best technique, indications, complications, and long-term results. The soft tissue envelope of the chin area usually follows the genial osseous movement approximately 90% or more, but the predictability ratio of horizontal reduction genioplasty is limited; it follows approximately 50% to 60%.[1] Reduction genioplasty surgical procedure results in narrowing or shortening of the chin. However, the

literature lacks data about the best technique, indications, complications, and long-term results.

approximately 90% or more, but the predictability ratio of horizontal reduction genioplasty is

The soft tissue envelope of the chin area usually follows the genial osseous movement

**Figure 1.** reduction genioplasty technique described by Ukan and park.

**Figure 1.** reduction genioplasty technique described by Ukan and park.

+

limited; it follows approximately 50% to 60%.1

**• Paranasal modification**

Piriform augmentation osteotomies **• Mandibular Angle modification**

160 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

Angle augmentation osteotomies

Malar augmentation osteotomies

Frontal Bossing reduction techniques

The creation or restoration of an esthetically pleasing facial contour can encompass many surgical approaches. Several surgical techniques are available for correcting and giving harmony to the lower third of the face.[1] In this respect, some well-known techniques seek to correct the shape and size of the chin using different kinds of chin implants or osteotomies in an effort to move it and change its spatial location, thus determining a new facial contour.

Genioplasty (anterior horizontal mandibular osteotomy) means a plastic procedure on the chin that involves both bony components (ie, anterior portion of the base of the mandible) and the soft tissue component.The procedure can be performed either alone or as an adjunct to other orthognathic and facial plastic surgeries. Either direct osteoplasty and soft tissue correction or implantation of an alloplastic material/cartilage/bone has been recommended for genioplasty. Since 1942, with first sliding advancement genioplasty that was described by Hofer, various genioplasty techniques with various indications, advantages, and disadvantages have been developed for correction of microgenia and macrogenia. In recent chapter we did not focused on augmentation genioplasty techniques.The readers can update their knowledge by review‐

In the event of anterior mandibular bony excess different surgical approaches can be used. Each have their own limitations and disadvantages. For instance simple burring down removal of bony excess from anterior mandible through an intraoperative approach will usually result

in an abnormal appearance and is not the best choice of treatment.

Angle reduction oeteotomies

Malar reduction osteotomies

**• Forehead modification**

**2. Chin modification**

**2.1. Augmentation genioplasty**

ing the other chapters or books.

**2.2. Reduction genioplasty**

**• Malar modification**

**Figure 2.** Horizontal T genioplasty and modified reduction genioplasty techniques.

asymmetry or unesthetic results could be increased(fig.1).1

**Figure 2.** Horizontal T genioplasty and modified reduction genioplasty techniques.

To date, only 2 articles have been published about the narrowing of the chin by use of this technique.Minor step-off at the chin-mandible junction and mild transient numbness of the lower lip, jowls, and bunching of the chin were reported as the most common complications of this technique. Because the lingual muscle is released, there is a risk of avascular necrosis of the distal segments, and the chin prominence should be minimally degloved to prevent this To date, only 2 articles have been published about the narrowing of the chin by use of this technique.Minor step-off at the chin-mandible junction and mild transient numbness of the lower lip, jowls, and bunching of the chin were reported as the most common complications of this technique. Because the lingual muscle is released, there is a risk of avascular necrosis

complication. Furthermore, because the mid-symphysis area is removed, the chance of

T osteotomy were also described but is not used widely(fig.2).10,46In 2013 we described1,47 a novel technique to reduce the prominent chin 3-dimentionally(fig.3).This new genioplasty (Zigzag genioplasty) makes it possible to decrease the vertical and transverse dimension of the chin alone or simultaneously, symmetrically or asymmetrically. This genioplasty alsomakesit possible to decrease the mental sagittal projection,if indicated, and simultaneously reduce the mandibular body height. Zigzag genioplasty allows one to properly correct excess of the chin(3-

another techniques such as horizontal

of the distal segments, and the chin prominence should be minimally degloved to prevent this complication. Furthermore, because the mid-symphysis area is removed, the chance of asymmetry or unesthetic results could be increased(fig.1).[1] another techniques such as horizontal T osteotomy were also described but is not used widely(fig.2).[10, 46]In 2013 we described[1, 47] a novel technique to reduce the prominent chin 3-dimentionally(fig.3).This new genioplasty (Zigzag genioplasty) makes it possible to decrease the vertical and transverse dimension of the chin alone or simultaneously, symmetrically or asymmetrically. This genioplasty alsomakesit possible to decrease the mental sagittal projection,if indicated, and simultaneously reduce the mandibular body height. Zigzag genioplasty allows one to properly correct excess of the chin(3-dimensionally), avoiding the need for muscular repositioning (except sometimes in types III and IV)(fig.4).A simple geometric calculation allows one to mobilize the chin in a vertical, horizontal, and sagittal direction,according to the needs of each patient. Furthermore, this design preserves the suprahyoid muscle attachmentsand the most important anatomic portion of symphysis area; narrowing the wide chin by this technique provides an esthetic and natural facial look.[1, 47]

**Figure 3.** Zigzag osteotomy design is based on the displacement of 2 bone fragments on the slopes of an inclined plane with a superior-medial direction. The degree of inclination for these slopes (the α and β- angles) will be estimated presurgically according to ; the extent of the vertical and transverse displacement wanted for a given case, mandibular symphysis height and width, the size of remained bone fragments after ostectomy, the need for conventional or ex‐ tended (to the mandibular body) reduction, the position of anterior mandibular teeth apices, the position of mental foramina and symmetrical or asymmetrical reduction.The posterior edges of the osteotomy, either could be finished just beneath the mental foramina (obtuse degree of inclination) or extended to the Anti-Gonial notch(acute degree of inclination),especially in such cases that, simultaneous reduction of inferior mandibular body osteotomy must be done, also. The amount of β-angle must be equal bilaterally except in asymmetrical cases.The anterior edge of the osteotomy which is extended medially from canine root apices (with a distance of 5 mm) to the mid-symphysis area, either could be extended above the inferior border(especially; in such cases which simultaneous advancement or set back should be done) or beyond it.As the same manner to posterior edge, the degree of inclination in the anterior part (the α-angle) could be determined pre-surgically,and must be equal in both sides except in asymmetrical cases.[from Keyhan et al. Zigzag genioplasty: a new technique for 3-dimensional reduction genioplasty. *Br J Oral Maxillofac Surg*.2013]

Advanced Adjunct Orthosurgical Esthetic Prodedures http://dx.doi.org/10.5772/59088 163

of the distal segments, and the chin prominence should be minimally degloved to prevent this complication. Furthermore, because the mid-symphysis area is removed, the chance of asymmetry or unesthetic results could be increased(fig.1).[1] another techniques such as horizontal T osteotomy were also described but is not used widely(fig.2).[10, 46]In 2013 we described[1, 47] a novel technique to reduce the prominent chin 3-dimentionally(fig.3).This new genioplasty (Zigzag genioplasty) makes it possible to decrease the vertical and transverse dimension of the chin alone or simultaneously, symmetrically or asymmetrically. This genioplasty alsomakesit possible to decrease the mental sagittal projection,if indicated, and simultaneously reduce the mandibular body height. Zigzag genioplasty allows one to properly correct excess of the chin(3-dimensionally), avoiding the need for muscular repositioning (except sometimes in types III and IV)(fig.4).A simple geometric calculation allows one to mobilize the chin in a vertical, horizontal, and sagittal direction,according to the needs of each patient. Furthermore, this design preserves the suprahyoid muscle attachmentsand the most important anatomic portion of symphysis area; narrowing the wide chin by this technique

**Figure 3.** Zigzag osteotomy design is based on the displacement of 2 bone fragments on the slopes of an inclined plane with a superior-medial direction. The degree of inclination for these slopes (the α and β- angles) will be estimated presurgically according to ; the extent of the vertical and transverse displacement wanted for a given case, mandibular symphysis height and width, the size of remained bone fragments after ostectomy, the need for conventional or ex‐ tended (to the mandibular body) reduction, the position of anterior mandibular teeth apices, the position of mental foramina and symmetrical or asymmetrical reduction.The posterior edges of the osteotomy, either could be finished just beneath the mental foramina (obtuse degree of inclination) or extended to the Anti-Gonial notch(acute degree of inclination),especially in such cases that, simultaneous reduction of inferior mandibular body osteotomy must be done, also. The amount of β-angle must be equal bilaterally except in asymmetrical cases.The anterior edge of the osteotomy which is extended medially from canine root apices (with a distance of 5 mm) to the mid-symphysis area, either could be extended above the inferior border(especially; in such cases which simultaneous advancement or set back should be done) or beyond it.As the same manner to posterior edge, the degree of inclination in the anterior part (the α-angle) could be determined pre-surgically,and must be equal in both sides except in asymmetrical cases.[from Keyhan et al.

Zigzag genioplasty: a new technique for 3-dimensional reduction genioplasty. *Br J Oral Maxillofac Surg*.2013]

provides an esthetic and natural facial look.[1, 47]

162 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

**Figure 4.** Schematic views of osteotomy design modifications of zigzag genioplasty technique (type I-VII). The anterior edge of the osteotomy could either be extended above the inferior border or beyond it. The posterior edges of the os‐ teotomy, could either be finished just beneath the mental foramina or extended up to the Anti-Gonial notch. For pure chin narrowing with minimal reduction in vertical dimension, bone removal just near the strut of bone in the middle should be done, and if vertical reduction is planned as well, bone strips should be removed above both posterior and anterior slobs. [from keyhan et.al. Zigzag genioplasty; patients evaluation, technique modifications and review of the literature. Br J oral amxillofac surg.2013] Figure reprinted with permission from The Br J oral amxillofac surg.

**Figure 5.** A simple geometric calculation allows one to mobilize the chin in a vertical, horizontal andsagittal direction, according to the needs of each patient the design of the planed osteotomy can be trace on the tracing paper and a sur‐ gical guide can be made simply.

**Figure 6.** A 29 years old man who underwent zigzag genioplasty(type III) in combination with rhinoplasty,buccal fat pad lifting[48],malar prosthesis and paranasal augmentation.a,b,c,d) Incision of the oral mucosa was performed 5 to 7 mm labial to the depth of the vestibule and directed horizontally. Then, the muco-periosteal flap was released, and the mental nerve was exposed. The chin prominence was degloved, and the lingual muscle attachments were maintained for blood supply. The osteotomy sites (type III) were marked with a surgical marker and the ostectomy was done with reciprocal saw and fissure bur In the next step, bone strips were removed bilaterally and the osteotomy was continued bilaterally, after down-fracturing, the interferences were removed,with high accuracy in maintain lingual pedicle tis‐ sues, detached supra-hyoids muscles was secured to the bone strut and medial and superior displacement was per‐ formed with the traction of two 10 centimeter wires.e) 2 L-shape miniplates were used for fixation.Any bone irregularity could be removed with round bur although, most often they could be remodeled post operatively. Vestib‐ ular incision was closed with 3-0 vicryl sutures.f,g)pre-operative views.h,i)post-operative views, simultaneous rhino‐ plasty and malar and para-nasal augmentation were performed also. [from keyhan et.al. Zigzag genioplasty ;patients evaluation,technique modifications and review of the literature. Am J Cosmetic surg,2013].**Figure reprinted with per‐ mission from The American Journal of Cosmetic Surgery**.
