Basics of Corrective Jaw Surgery

by Wendall Mascarenhas, DDS, MD, FRCD(C); Brian Farrell, DDS, MD, FACS

Orthognathic surgery (OGS), often referred to as “corrective jaw surgery,” includes a variety of procedures that can help manage malocclusion, constricted airway, and esthetics.

OGS can be beneficial for functional concerns such as temporomandibular dysfunction from repetitive posturing of the jaw necessary with limited tooth contact that leads to muscle aches and osteoarthritis of the joints. Difficulty chewing completely through food from an openbite malocclusion and periodontal concerns on the palate adjacent to a deepbite relationship or recession from a narrow transverse arch form are additional areas where OGS may be beneficial. Another functional concern that can arise from a dentofacial deformity is a narrow airway space posterior to the tongue creating obstructive sleep apnea. Obstructive sleep apnea often leads to cardiac and respiratory concerns in addition to mental fatigue such as daytime sleepiness and altered thinking.

Although OGS has been around for decades, continued evolution in technology, digital surgical planning, and anesthesia have transformed the surgical workflow and improved outcomes. What was once a long and arduous procedure that often required lengthy hospitalization is now routinely done in ambulatory settings as an outpatient procedure. OGS has an extremely high patient satisfaction rate (90%), with 88.2% of patients saying they would do the surgery again and 94.1% reporting they would recommend it to someone else.1

OGS generally involves three procedures to orient the upper and lower jaw into a balanced and harmonious position to establish an ideal occlusion, facial balance and increase patency of the airway. The three procedures are the Lefort 1 osteotomy (LF1), bilateral sagittal split osteotomy (BSSO), and genioplasty. By using one or more of these procedures, almost any movement of the maxilla and mandible is possible, and patients can experience dramatic improvements to their function, breathing, and facial appearance.

A Lefort 1 ostetomy is a horizontal osteotomy of the maxilla superior to the roots of the dentition and inferior to the infraorbital nerve. It is performed through an intraoral vestibular incision, and after mobilization it allows the maxilla to be moved in any direction. The most common procedure is a Lefort 1 advancement to move the maxilla anteriorly, increasing midface projection and incisal show on smile. (Fig. 1a-d)

Fig. 1A

 Lefort 1 advancement of the maxilla resulting in an improved occlusion, profile, and esthetics.
Lefort 1 advancement of the maxilla resulting in an improved occlusion, profile, and esthetics.

Fig. 1B

 Lefort 1 advancement of the maxilla resulting in an improved occlusion, profile, and esthetics.
Lefort 1 advancement of the maxilla resulting in an improved occlusion, profile, and esthetics.

Fig. 1C

 Lefort 1 advancement of the maxilla resulting in an improved occlusion, profile, and esthetics.
Lefort 1 advancement of the maxilla resulting in an improved occlusion, profile, and esthetics.

Fig. 1D

 Lefort 1 advancement of the maxilla resulting in an improved occlusion, profile, and esthetics.
Lefort 1 advancement of the maxilla resulting in an improved occlusion, profile, and esthetics.

A BSSO is the most common mandibular surgery and involves performing a sagittal osteotomy within the ramus. Once the mandible is “split” bilaterally, the distal tooth-bearing segment can be advanced or set back into the desired position typically determined through virtual surgical planning (VSP). Rigid fixation, with miniplates and screws, is used to stabilize the osteotomy and allow opening and closing of the jaw immediately (patients are not wired together as in years past). The most common orthognathic procedure is advancement of the lower jaw that often results in dramatic improvements to a patient’s profile, occlusion, and airway. (Fig. 2a-d)

Fig. 2A

2A-D. BSSO advancement of the mandible resulting in an improved profile, esthetics, and airway
BSSO advancement of the mandible resulting in an improved profile, esthetics, and airway

Fig. 2B

BSSO advancement of the mandible resulting in an improved profile, esthetics, and airway
BSSO advancement of the mandible resulting in an improved profile, esthetics, and airway

Fig. 2C

BSSO advancement of the mandible resulting in an improved profile, esthetics, and airway
BSSO advancement of the mandible resulting in an improved profile, esthetics, and airway

Fig. 2D

BSSO advancement of the mandible resulting in an improved profile, esthetics, and airway
BSSO advancement of the mandible resulting in an improved profile, esthetics, and airway

A genioplasty is a bony cut of the inferior border of the anterior mandible. Mobilization of the chin allows the bone to be repositioned in multiple dimensions to improve facial balance, symmetry, and proportion. Advancement is the most common form of genioplasty as repositioning of the chin forward can improve the profile esthetically and is functionally advantageous improving lip competence, particularly when the lower face is vertically excessive. (Fig. 3a-3b)

Fig. 3A

. Isolated genioplasty
advancement, improving the patient’s profile as well as reducing mentalis strain and reported lip incompetence.
Isolated genioplasty advancement, improving the patient’s profile as well as reducing mentalis strain and reported lip incompetence.

Fig. 3B

. Isolated genioplasty
advancement, improving the patient’s profile as well as reducing mentalis strain and reported lip incompetence.
Isolated genioplasty advancement, improving the patient’s profile as well as reducing mentalis strain and reported lip incompetence.

Traditional surgical planning can be divided into “single jaw” or “double jaw” cases with focus on the occlusion, facial balance, and smile esthetics; in particular the position of the maxillary central incisors. Isolating the surgical procedure to a single jaw requires the opposing dentition and associated skeleton to be in ideal position with regards to anterior/posterior positioning, transverse dimension, vertical position, and symmetry. In single jaw cases, the maxilla OR mandible is moved and set into the final occlusion based on the reference of the opposing arch through fabrication of a splint.

In double jaw surgery, both the maxilla AND mandible are moved through reference of the opposite jaw. Surgery is initiated to passively mobilize the initial jaw to allow the tooth bearing segment to be repositioned based on the reference of the opposing stable dentition through an “intermediate” splint. Once the initial jaw has been fixated and the movement confirmed through verification into the splint, surgery can proceed to the second jaw. The second jaw is now mobilized to the desired occlusion through reference of jaw previously completed with a “final” splint.

Genioplasties can be performed concomitantly with single or double jaw surgery (known as a “triple jaw” when added to a double jaw procedure). By combining movements of the maxilla, mandible, and chin, patients can experience dramatic improvement in their occlusion and facial balance. (Fig. 4a-f)

Fig. 4A

Combination surgery involving both the upper and lower jaws, dramatically improving her occlusion, function, and smile.
Combination surgery involving both the upper and lower jaws, dramatically improving her occlusion, function, and smile.

Fig. 4B

Combination surgery involving both the upper and lower jaws, dramatically improving her occlusion, function, and smile.
Combination surgery involving both the upper and lower jaws, dramatically improving her occlusion, function, and smile.

Fig. 4C

Combination surgery involving both the upper and lower jaws, dramatically improving her occlusion, function, and smile
Combination surgery involving both the upper and lower jaws, dramatically improving her occlusion, function, and smile

Fig. 4D

Combination surgery involving both the upper and lower jaws, dramatically improving her occlusion, function, and smile
Combination surgery involving both the upper and lower jaws, dramatically improving her occlusion, function, and smile

Fig. 4E

Combination surgery involving both the upper and lower jaws, dramatically improving her occlusion, function, and smile
Combination surgery involving both the upper and lower jaws, dramatically improving her occlusion, function, and smile

Fig. 4F

Combination surgery involving both the upper and lower jaws, dramatically improving her occlusion, function, and smile
Combination surgery involving both the upper and lower jaws, dramatically improving her occlusion, function, and smile

Prior to evolution of digital dentistry, isolated single jaw surgeries involved laboratory time with stone models fabricated from alginate impressions. These models were mounted on a Galetti articulator to haptically establish the desired occlusion followed by creation of an acrylic splint. (Fig. 5) Surgeries that encompassed both the maxilla and mandible were traditionally completed by transferring the malocclusion to a semi-adjustable articulator through facebow transfer and a centric relation bite. (Fig. 6) Traditional model surgery was labor intensive, prone to errors throughout the work up and there was a loss of perspective of the skeleton and face when limited to only the visualizing the dentition on a lab bench. Error can be introduced throughout the surgical work up through inaccurate impressions, models, facebow record, centric relation record altering the mounting, improper model surgery or within the splint fabrication stages. Even a minute error at each stage can compound and lead to a dramatically different surgical result. This is further exacerbated for more challenging cases such as facial asymmetry or those that require significant occlusal plane changes as traditional model surgery does not provide perspective of the dentofacial deformity.2

Fig. 5

 Traditional single jaw surgery involving mounted stone models on a Galetti articulator and fabrication of an acrylic splint.
Traditional single jaw surgery involving mounted stone models on a Galetti articulator and fabrication of an acrylic splint.

Fig. 6

Traditional model surgery involving a semi-adjustable articulator, stone models, and manual surgical movements of the casts.
Traditional model surgery involving a semi-adjustable articulator, stone models, and manual surgical movements of the casts.

Computer assisted surgical simulation (CASS) has evolved through advances in imaging and technology and is widely regarded as the standard of care for management of dentofacial deformities. CASS, cone beam computed tomography (CBCT) and intra-oral scanning (IOS) are used to establish a digital workflow and greatly reduce the amount of time required to plan a case.3 In addition, by eliminating the need for a facebow record, alginate impressions, stone pour ups, and articulator use, the error induced in the planning process is reduced.4,5 (Fig. 7)
The expanded perspective provided with virtual surgical planning of both the malocclusion AND skeletal deformity has improved treatment planning, preoperative insight into surgical management and intraoperative efficiency that results in better overall outcomes.

Fig. 7

Virtual surgical planning allowing three dimensional analysis of the facial skeleton, profile, and final occlusal setup.
Virtual surgical planning allowing three dimensional analysis of the facial skeleton, profile, and final occlusal setup.

Advancements in recovery after orthognathic surgery have come a long way over the decades. The most common fear of patients when the topic of jaw surgery is mentioned is that they will be “wired shut” for 6 weeks. Although this was routine practice in the age of wire fixation, the advent of rigid fixation via titanium plates and screws has rendered this practice extremely rare, if not extinct. Patient’s now leave the operating room with nothing more than light guiding elastics, allowing them to speak, open their mouth, and drink immediately post-operatively. Patient’s still follow a liquid diet post-operatively, which slowly progresses to a non-chew diet and then normal diet over a period of 6 weeks. Patients often take at least 2 weeks off from school or work, but commonly resume light activities in the third week after surgery as the calories get more substantial and “life” resumes.

Although most orthodontic cases do not require surgery, orthognathic surgery is a proven procedure that can offer great improvement to patient’s occlusion, facial profile, airway, and esthetics. What was once a very daunting procedure and recovery has become a routine operation performed hundreds of times a year by some oral and maxillofacial surgeons. Modernizing the digital workup and surgical planning has resulted in faster, more accurate surgery whilst still retaining the principles upon which the surgery was intended. In Canada, we are fortunate that the majority of costs are covered by public provincial health care plans, and patients are usually required to pay only for their orthodontic treatment and a small work-up fee associated with CASS. Portions of this work-up fee are often covered for patients who have private insurance, and this is something that can be discussed with the surgeon directly during the patient’s initial consultation visit.

Oral Health welcomes this original article.

References

  1. Keefe SH, Keefe MG, Hui B, Pogrel MA. Patient motivation and satisfaction from orthognathic surgery-a case series. Oral Surg Oral Med Oral Pathol Oral Radiol. 135(2):e15-e24, 2023
  2. Sharifi A, Jones R, Ayoub A, Moos K, Walker F, Khambay B, McHugh S. How accurate is model planning for orthognathic surgery? Int. J. Oral Maxillofac. Surg. 37: 1089–1093, 2008
  3. McCormick SU, Drew SJ: Virtual Model Surgery for Efficient Performance. J Oral Maxillofac Surg 69:638-644, 2011
  4. Hsu SS, Gateno J, Bell RB, Hirsch DL, Markiewicz MR, Teichgraeber JF, Zhou X, Xia JJ. Accuracy of a computer-aided surgical simulation protocol for orthognathic surgery: a prospective multicenter study. J Oral Maxillofac Surg 71(1):128-42, 2013
  5. Zhang N, Liu S, Hu Z, Hu J, Zhu S, Li Y. Accuracy of virtual surgical planning in two-jaw orthognathic surgery: comparison of planned and actual results. Oral Surg Oral Med Oral Pathol Oral Radiol. 122(2):143-51, 2016

About the Authors

Dr. Wendall Mascarenhas, is an Oral and Maxillofacial Surgeon who maintains a private practice in Brampton, ON. He is an Assistant Professor, University of Toronto, and an attending staff with the OMFS training program at Mt. Sinai Hospital. He is a supervisor of the Surgical Orthodontic clinic where he trains orthodontic and OMFS residents in orthognathic surgery.

Dr. Brian Farrell, is an Oral and Maxillofacial Surgeon who maintains a large group practice based in Charlotte, NC. He is the fellowship director for the Carolina’s Centre for Oral and Facial Surgery, and has lectured internationally on orthognathic surgery.

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