Validity of Medical Insurance Guidelines for Orthognathic Surgery

Abstract

Purpose

The purpose of this study was to assess the validity of orthognathic surgery guidelines used by the major American medical insurance companies.

Materials and Methods

This study assessed the validity of the orthognathic surgery guidelines used by Aetna, Anthem Blue Cross Blue Shield (BCBS), Cigna, Humana, and UnitedHealthcare (UHC). To evaluate the validity, we calculated the approval and denial rates of the 5 guidelines when we used them to assess the medical necessity for a control group of carefully selected patients. Patients were included in the control group if they met the criteria of a 'prudent provider,' crafted for this study. All rejected cases were analyzed to determine the root cause of the denials. The validity of the guidelines was also ascertained by determining their completeness and correctness.

Results

The current study proves that no insurance guideline is in agreement with the criteria of a 'prudent provider'. When applied to carefully chosen patients, the requirements of BCBS, Aetna, Humana, and Cigna produce modest rejection rates of 6-12%. UHC is an outlier. Its guideline rejects 86% of patients, a rate about 7 times higher than its peers. Insurance guidelines disqualified patients for 3 different reasons: (1) no significant jaw deformity, (2) no demonstrable health impairment, and (3) the etiology of the condition is not a covered benefit. Additional evaluations demonstrate that the private insurance guidelines are incomplete and, at times ,incorrect.

Conclusion

This study shows that the orthognathic surgery guidelines used by the major American medical insurance plans need revision. The most consequential flaw was considering etiology in judging medical necessity. Fortunately, only one company adopted this policy. Moreover, all guidelines have omissions and errors in the way jaw deformity is determined and how health impairment is determined.

Introduction

Some people are born with jaw deformities; others develop the anomalies during their lifetime. Jaw deformities can affect the shape, size, position, orientation, and symmetry of the maxilla and mandible.¹ Depending on how the jaws are affected, the malformations may produce one or more anatomic derangements: malocclusion, narrowing of the airways, and facial disfigurement. The anatomic derangements may disrupt the health of an individual by hindering jaw function, by promoting oral injury, or by initiating or aggravating a disease. Jaw deformities require treatment when they affect the health of the patient—health being a state of complete physical, mental and social well-being, and not merely the absence of disease or infirmity.²

Many patients with jaw deformities can be treated with orthodontics; others require orthognathic surgery. It has been estimated that 5% of the United States (US) population requires these operations.³

In the US, the majority of the population (67%) receives health services through private insurance plans.⁴ Private plans limit orthognathic surgeries to those patients who have coverage and meet their criteria for medical necessity.^5-9 In practice, however, their guidelines produce frequent denials.^5-9 When inappropriate, the denials harm providers, payers, and patients alike. In the case of providers, incorrect denials cause frustration and additional uncompensated work. For third-party payers, improper rejections infuriate clients, anger providers, and increase administrative costs. Concerning patients, the denials delay treatment, prevent cure, and increase costs.

Our observation is that most inappropriate denials result from imprecise medical necessity guidelines. Therefore, an unbiased assessment of current guidelines is needed. The purpose of this study was to assess the validity of the orthognathic surgery guidelines used by the major American medical insurance companies—validity meaning the quality of being logical or factually sound.

Materials and Methods

This retrospective study was conducted at Houston Methodist Hospital in Houston, Texas, after receiving an Institutional Review Board approval (PRO00025630). The study assessed the validity of the orthognathic surgery guidelines used by the major American medical insurance companies: Aetna, Anthem Blue Cross Blue Shield (BCBS), Cigna, Humana, and UnitedHealthcare (UHC). To evaluate the validity, we calculated the approval and denial rates of the 5 insurance guidelines when we used them to assess the medical necessity for a control group of carefully selected patients.

All rejected cases (sentinel events) were analyzed to determine the root cause of the denials. The validity of the guidelines was also assessed by ascertaining their completeness and correctness. These characteristics were determined by comparing each insurance guideline with a yardstick guideline we crafted for a prudent provider. A prudent provider is the average judicious provider that practices the standard of care of his/her community.¹⁰

Before patient selection, the investigators met to uncover the criteria of prudent providers. The group of investigators included an orthodontic graduate student (SS), an oral and maxillofacial surgery fellow (KC), a senior academic orthodontist (JE), and a senior academic oral and maxillofacial surgeon (JG).

The group adopted the American Medical Association's definition of medical necessity: Health care services or products that a prudent physician would provide to a patient for the purpose of preventing, diagnosing or treating an illness, injury, disease or its symptoms in a manner that is: (a) in accordance with generally accepted standards of medical practice; (b) clinically appropriate in terms of type, frequency, extent, site, and duration; and (c) not primarily for the economic benefit of the health plans and purchasers or for the convenience of the patient, treating physician, or other health care provider.¹¹

After review of all pertinent literature^12-83 at several consensus meetings, the group agreed to the following criteria for orthognathic surgery: (1) One or both jaws are deformed; that is, the jaw configuration prevents the normal articulation of teeth, narrows the airway, or disfigures the face. (2) The deformity impairs health by impairing function, by promoting injury, or by causing or aggravating a disease. (3) There is no equally effective, less complicated treatment. (4) The surgery is appropriate for the patient. These criteria became the inclusion criteria for the study.

The search for patients in our medical records was limited to patients seen after June 2018, by a single provider (JG). In June 2018, we had developed, for our clinical practice, a single data collection form that amalgamated all the information required by the different insurance guidelines. This document was added to our orthognathic consultation template, part of our electronic medical record system. We only selected orthognathic surgery consults from a single provider because he was meticulous at measuring and recording all the data fields in the form. In addition to collecting data from the clinical notes, we also collected the cephalometric analyses. Patients were added to the study group if their medical records were complete, and they met our criteria for orthognathic surgery. We studied 110 patients that met the research criteria.

To determine approval or denial according to the different insurance guidelines, we developed scoring grids for each insurance company. Because orthognathic surgery can be deemed medically necessary under guidelines for orthognathic surgery, obstructive sleep apnea, or temporomandibular joint disorders, the grids combined the 3 separate guidelines.^{6-9, 84-94} A single calibrated investigator (SS), not familiar with the patients, reviewed the de-identified clinical records and scored each patient according to the 5 payers' guidelines. The assessment of the clinical records was objective. No subjective assessments were allowed. Only those anatomical and functional derangements that were unambiguously documented in the medical records were scored.

All data were collected and analyzed in Microsoft Excel. Descriptive statistics were used to present the findings.

Results

The sample population had a median age of 20 years, with a range of 12 to 57 years. The age distribution of the test population was skewed (Fig. 1). Most patients were adolescents and young adults. Fifty-five percent of the patients were females. The patients had different types of jaw deformities (Fig. 2); most had more than one type of malformation.

Figure 1.

Age distribution of the test population

Figure 2.

Jaw deformities in the test population

We applied the insurance criteria of 5 different insurance companies to 110 patients that met the prudent provider criteria for orthognathic surgery—a total of 550 evaluations. In 139 instances (25%), the insurance guidelines denied coverage.

The approval and rejection rates of the different insurance guidelines can be seen in Fig. 3. All insurance guidelines approved fewer patients than prudent providers. BCBS, Aetna, Humana, and Cigna had similar approval rates (88 - 94%). UHC was a significant outlier. It only approved 14% of patients, a rate nearly 6.5 times lower than their peers.

Figure 3.

Approval and denial rates

Insurance guidelines denied patients for 3 different reasons: (1) no significant deformity, (2) no demonstrable health impairment, and (3) the etiology of the condition was not a covered benefit (Table 1).

Table 1.

Number of Denials by Reason

	No Significant Deformity	No health impairment	Etiology not covered	Total
UHC	3	5	90	98
Cigna	1	12	0	13
Aetna	1	10	0	11
Humana	5	8	0	13
BCBS	1	6	0	7
TOTAL	11	41	90	142

No Significant Deformity

According to the guidelines of one or more insurance companies, 5 patients failed to qualify for orthognathic surgery because their deformities were not significant. In this group of 5 sentinel patients, we identify 3 scenarios (Table 2).

Table 2.

Surgery Denied Because No Significant Deformity

Scenarios	Humana	UHC	BCBS	Cigna	Aetna
A-P skeletal discrepancy hidden by the malocclusion	•	•	•	•	•
Bimaxillary retrusion with normal occlusion and OSAS	•
Excessive maxillary vertical displacement	•

(•) denied

The first case is that of patients with substantial anteroposterior jaw discrepancies that were not revealed by assessing the occlusion. The situation comes to life in one of our patients. The patient had symptomatic mandibular retrognathia, but all the insurance guidelines rejected his surgery because the incisal overjet of 4 mm was below the qualifying threshold of 5 mm. However, the patient had a large skeletal (anteroposterior) discrepancy. The ANB angle was 9.4 degrees; the Wits Appraisal was 10.3 mm; and Maxillary Convexity was 13.1 mm—all greater than 2 standard deviations from the mean. In this patient, the overjet was only 4 mm because the lower incisors were compensated in severe labioversion. The treating orthodontist had determined that he could not correct the excessive overjet without surgery. Notwithstanding, all insurance guidelines denied the operation because none consider skeletal measurements in the assessment of prognathism or retrognathism.

The other situation that causes denial is that of patients with bimaxillary retrusion, obstructive sleep apnea, and normal occlusion. Two patients embodied this scenario. One had moderate OSAS, the other severe. Both patients were rejected by the Humana guideline, but approved by the others. The rejecting guideline required an occlusal discrepancy for medical necessity and did not consider the skeletal dysplasia.

The last scenario is that of patients with excessive maxillary downward displacement (i.e., vertical maxillary excess). The situation was personified by 2 patients that were rejected by the Humana guideline, but approved by the others. Humana does not have a metric to assess the vertical maxillary position.

We also evaluated the insurance guidelines for their ability to assess all types of jaw deformities. We began the investigation by listing all possible diagnoses related to jaw deformities. Then, we searched the guidelines for any metric—dental or skeletal—that could potentially support the diagnosis (Table 3). The most encompassing guidelines were Aetna's and Cigna's; however, they only had criteria for 73% of the items. Next, were UHC with 65%, BCBC with 62%, and Humana with 54%.

Table 3.

Severity of Deformity Criteria

	Aetna		Cigna		UHC		BCBS		Humana
CRITERIA TYPE	Dental	Skeletal	Dental	Skeletal	Dental	Skeletal	Dental	Skeletal	Dental	Skeletal
Anterior Open Bite	•	•	•	•	•	•	•	•	•
Posterior Open Bite	•	--	•	--	•	--	•	--	•	--
Supraeruption of Posterior Teeth	•	--	•	--	•	--	•	--	•	--
Jaw Hyperplasia	•	•	•	•	•		•		•
Jaw Hypoplasia	•	•	•	•	•		•		•
Retrognathism	•		•		•		•		•
Prognathism	•		•		•		•		•
Laterognathia	•	•	•	•	•	•	•	•	•	•
Excessive Vertical Displacement		•		•		•		•
Insufficient Vertical Displacement		•		•		•
Asymmetry		•		•		•		•		•
Pitch Malrotation
Yaw Malrotation	○	○	○	○	○	○	○	○	○	○
Roll Malrotation	○	○	○	○	○	○	○	○	○	○

(•) included in the guideline; (--) not Applicable; (○) indirectly covered under asymmetry; ( ) missing

No Health Impairment

Thirteen of 110 patients were denied surgery by one or more insurance companies because the deformity did not impair their health (Table 4). Two of the patients were refused surgery despite having 2 qualifying reasons.

Table 4.

Surgery Denied Because No Health Impairment

Surgery denied because …	Aetna	BCBS	Cigna	Humana	UHC
… altered body image, reduced quality of life, and poor self-esteem were not considered	•	•	•	•	•
… oral injuries caused by malocclusion were not considered	•		•	•
… speech distortion in the absence of cleft lip and palate was not considered	•
… speech distortion was not assessed by a speech-language pathologist		•	•
… mild OSAS, even when symptomatic, was not considered					•

(•) denied

Among the 13 rejected patients, we found 5 different reasons for the denial. The first reason was that facial disfigurement, even when it affects the patients' health (altered body image, reduced quality of life, and poor self-esteem), is not a qualifying impairment in the insurance guidelines. The guidelines consider facial disfigurement a cosmetic problem. The second reason for denial was that oral injuries (e.g., biting the hard palate or the cheeks) are not recognized by 3 payers: Aetna, Cigna, and Humana. This lapse caused the rejection of 4 patients. The third reason was that speech distortion, in the absence of cleft lip and palate, is not a qualifying impairment. Only Aetna used this criterium, which affected 2 patients. The fourth reason was that a speech-language pathologist had not assessed the patient's speech impediment. Anthem-BCBS and Cigna require this higher standard of proof that was not sought by our prudent providers. This requirement affected 2 patients. The fifth reason was that UHC disqualifies patients with mild OSAS (AHI or RDI ≥5 and < 15) from orthognathic surgery, even when they are symptomatic, have comorbidities, have failed medical therapy, or have failed phase I surgeries. UHC denied 2 patients for this reason.

We also assessed the payers' guidelines to measure how thoroughly they cover the health conditions that are affected by jaw deformities. Table 5 presents the results. In the first column, we list 15 health items that are associated with jaw deformities. No insurance guideline considered all possible health conditions (Table 5). The most encompassing guidelines were those of UHC and BCBS, covering 47% of items. Humana and Cigna covered 33% of items, and Aetna 26%. Besides, some payers have prerequisites for covered items. Aetna considers speech impairment only for those patients with cleft lip and palate. UHC finds OSAS a medical necessity for orthognathic surgery only for patients with moderate and severe disease.

Table 5.

Impairments of Health Related to Jaw Deformities

	UHC	BCBS	HUMANA	CIGNA	Aetna
Function
Mastication	•	•	•	•	•
Speech	•	○	•	○	◊
Swallowing	•	•	•	•
Breathing			•		•
In society (altered body image, reduced quality of life, or poor self-esteem)
Injury
Biting (wounding) palate	•	•
Biting lip	•	•
Biting cheeks	•	•
Dental attrition
Dental fractures
Disease
OSAS	□	•	•	•	•
Myofascial Pain				•
TMJ internal derangement
TMJ arthritis
Chronic gingivitis from oral breathing

(•) Covered; (○) If determined by SLP; (◊) Only in cleft patients; (□) Only in moderate or severe OSAS

The Etiology of the Condition Was Not a Covered Benefit

In the study, UHC was the only payer that disqualified patients because of the etiology of the jaw deformity (Table 1). Their guideline rejected 90 patients for this reason. UHC considers orthognathic surgery medically necessary only when the jaw deformity results from a congenital anomaly, an acute traumatic injury, tumors, and cysts. All other causes are not covered unless the deformity causes obstructive sleep apnea.⁶

Discussion

Key Results

The current study proves that no insurance guideline is in agreement with a 'prudent provider.' When applied to carefully chosen patients, the criteria of BCBS, Aetna, Humana, and Cigna produce modest rejection rates of 6-12%. UHC is an outlier. Its guide rejects 86% of patients, a rate many times higher than its peers. Insurance guidelines disqualified patients for 3 different reasons: (1) no significant jaw deformity, (2) no demonstrable health impairment, and (3) the etiology of the condition is not a covered benefit (Fig. 4). Additional analyses demonstrated vast shortcomings in the current guidelines. We discuss them below under the interpretation of results.

Figure 4.

Reason for denial

Limitations

When assessing the results of this study, the reader should consider the following limitations. First, the private insurance guidelines, we assessed, were active in 2018. Some may have been updated since. Second, Blue Cross Blue Shield is a national association of 36 independent, community-based, and locally operated companies.⁹⁵ Many local companies have their medical necessity guidelines. For this study, however, we selected the Anthem's guidelines because Anthem is the largest company in the BCBS Association.⁹⁶ Third, the language of some of the guidelines is broad. For example, Humana considers a functional impairment any "direct and measurable reduction in physical performance of an organ or body part." ⁵ When the guidelines were broad, we assumed that any reasonable inclusion would be covered. In practice, however, the plan may be more restrictive.

Finally, in interpreting the results of this study, the reader should appreciate the difference between medical necessity and coverage; our study examined the first and not the second. On the one hand, coverage is the list of benefits included in the insurance policy (i.e., what is included and what is excluded). On the other hand, medical necessity (for an insurance carrier) is the decision by a health plan that treatment is necessary for the health of the beneficiary. ⁹⁷ Unfortunately, some private policies exclude orthognathic surgery.^{6, 7, 92} Patients with these policies receive automatic rejections, never getting a determination of medical necessity.

Interpretation of Results

As mentioned above, UHC's guideline rejects patients at a rate many times higher than their peers. Why the difference? UHC is the only company that disqualifies patients based on the origin of the jaw deformity. According to UHC, orthognathic surgery is medically necessary only when the jaw deformity is congenital, or when it results from an acute traumatic injury, tumor, or cyst. Other jaw deformities are deemed medically necessary only if they cause obstructive sleep apnea.⁶

UHC's rule excludes 3 large groups of patients: (1) those with inherited jaw dysplasias that do not manifest at birth (e.g., mandibular prognathism), (2) those that are caused by abnormal function (e.g., an anterior open bite from oral breathing), and (3) those that are caused by diseases (e.g., micrognathia from juvenile idiopathic arthritis). This inequity creates incongruous situations that we can best illustrate with examples.

First, let us consider 2 patients. One was born with Treacher Collins Syndrome; another develops juvenile idiopathic arthritis (JIA) at age 3. In both conditions, the mandible fails to grow, in Treacher Collins because the condylar cartilage (growth site) never forms, in JIA, because it is destroyed in early life. Both patients will have micrognathia and impaired mastication for the rest of their lives. Although both patients have the same problem, UHC's guidelines will approve treatment for the first, but not for the second.

Another example follows. The first patient is born with hemifacial microsomia; the second develops unilateral condylar hyperplasia in adolescence. In early adulthood, both patients have equivalent jaw deformities: mandibular asymmetry and maxillary malrotation (canting), yet UHC guideline will approve the first, but will deny the second.

The above situations are unfortunate. Furthermore, they do not occur elsewhere in medicine. Our healthcare system does not discriminate against patients because of the etiology of their conditions. Thin patients with type 2 diabetes get the same benefits as those who are obese. Smokers and non-smokers alike receive treatments for COPD and lung cancer. Therefore, we encourage UHC to revise its guidelines. It must follow the community standard.

In the present study, the second most common reason for denial is no demonstrable health impairment (27% of all denials). Within this category, we found 5 different explanations for refusal. The first explanation is that altered body image, reduced quality of life, and poor self-esteem because of facial disfigurement did not qualify patients for surgery. Prudent providers, however, have no choice but to consider facial disfigurement as an indication for orthognathic surgery, when it affects the health of the patient. Our job is to restore health to our patients, and health is the state of complete physical, mental and social well-being, not merely the absence of disease or infirmity.²

The face serves a dual role as both a biological organ and an organ of identity.⁹⁸ As important as its physiological functions is the key role of the face in identity.⁹⁸ The face is the primary means by which humans recognize and interact with each other.^{98, 99} Whether congenital or acquired, facial disfigurement can have profound psychosocial implications, including altered body image, reduced quality of life, and poor self-esteem. ^{98, 100-103}

Interestingly, a couple of guidelines accept the impact of facial disfigurement in a veiled manner, by making exceptions for patients with congenital facial deformities (e.g., Robin Sequence, Treacher Collins Syndrome, hemifacial microsomia, and craniofacial synostosis).^{5, 6} Private payers, however, fail to appreciate that patients with postnatal deformities (e.g., unilateral condylar hyperplasia, JIA, TMJ ankylosis, and mandibular prognathism) can have disfigurements that are as distressing, or more devastating than those seen in some congenital conditions.

There is also a difference between cosmetic and reconstructive surgeries. Cosmetic surgery is any operation that is done to enhance the appearance of a normal structure (e.g., rejuvenating an aged face).¹⁰⁴ In contrast, reconstructive surgery is any operation that corrects abnormal anatomy.¹⁰⁵ Consequently, we must deduce that orthognathic surgery could never be cosmetic because it is done to correct abnormal form (i.e., deformity).

The second explanation for the denial, due to no demonstrable health impairment, is that oral injuries caused by malocclusion (e.g., biting soft-tissues, fracturing teeth, dental attrition) were not considered. Three insurance guidelines ignore this problem (Aetna, Cigna, and Humana), and none considered hard-tissue injuries. Hence, we recommend they add these health impairments to their guidelines.

The third explanation for denial was that a speech impediment, in the absence of cleft lip and palate, does not qualify a patient for surgery. This criterium, unique to Aetna, goes against current knowledge. Certain malocclusions (i.e., excessive overjet, anterior crossbite, and anterior open bite) can hinder normal speech, by causing misarticulations.^30-32 Cleft status does not change this fact. When patients misarticulate because they cannot compensate for a malocclusion—and the deformity cannot be corrected with orthodontics—recommending orthognathic surgery is reasonable. Besides, the most frequent speech problems in cleft lip and palate patients cannot be corrected with orthognathic surgery. Such problems are hypernasality and compensatory misarticulations (e.g., glottal stops, nasal fricatives, and pharyngeal fricatives). ^{106, 107}

The fourth explanation for the denial, related to no health impairment, was that a speech-language pathologist had not assessed the speech disorder. BCBS and Aetna required this higher standard of proof. As prudent providers, we have no qualm with this request, but we did not include it in our criteria because we felt competent in making this assessment.

The fifth and last reason was that UHC does not approve orthognathic surgery for patients with mild OSAS (AHI or RDI ≥5 and < 15), even when they are symptomatic, have comorbidities, have failed medical therapy, or have failed other surgeries. This policy is contrary to the recommendations of The American Academy of Sleep Medicine (AASM) and the Center for Medicare and Medicaid Services (CMS). Both entities recommend treating patients with mild OSAS who are symptomatic or have comorbid conditions.^{108, 109, 110, 111}

Besides the above problems, no private insurance guideline considers the age of the OSAS patient in deciding medical necessity. OSAS in the young, however, is different from that of the adult.^{109, 112-114} For example, the AHI thresholds are different. In pediatrics, any AHI over 1 is abnormal; in adults, the threshold is 5. In pediatrics, the divide for severe disease is 10; in adults, it is 30.¹¹² Moreover, in pediatrics, primary treatment is surgical, for a cure (e.g., adenotonsillectomy, rapid maxillary expansion, jaw advancement).¹¹² In adults, primary treatment is medical for control a chronic condition (e.g., positive airway pressure, oral appliances).^{109, 112-114}

Unfortunately, the boundary between the pediatric and adult populations is unsettled. Some experts apply pediatric criteria to all patients under 18. Others make the separation at 13.¹¹² The controversy is consequential because many patients that need orthognathic surgery are in the grey zone of adolescence. This predicament is an artifact of medicine. Physiologic sleep and sleep-disordered-breathing do not change drastically at a given birthday. Thus, prudent providers can make a strong case for primary orthognathic surgery in adolescent patients with OSAS and craniofacial disproportions.¹¹³ Curing these patients in early life must be superior to managing their chronic conditions for 60 years.¹¹⁴

Now that we have discussed the 2 most common reasons for private insurance plan denial (etiology not covered and no health impairment), we should consider the third and last reason: no significant deformity. Rejections in this category occurred because the current insurance guidelines are underdeveloped (Table 3).

Skilled clinicians can diagnose a jaw deformity as effortlessly as a layperson can recognize a portrait of Abraham Lincoln. For an expert clinician, every deformed face is famous. The diagnosis is intuitive and involves pattern recognition. To avoid provider bias, however, guidelines for medical necessity discount the provider's intuition in favor of objective criteria.

To spot a jaw deformity, the objective criteria must assess the structure of the jaws (bones) and the arrangement of the teeth. Abnormal bone configurations signal a jaw deformity. Likewise, deviations of the occlusion that cannot be explained by intra-arch misalignment. A common belief is that jaw deformities invariably affect the dental occlusion. This notion is a misconception. A bone deformity can affect a single jaw, both jaws unequally, or both jaws in a parallel fashion. The first two conditions create discrepancies in the matching configurations of the upper and lower jaws, resulting in malocclusion. The last condition causes no discrepancy and does not change the bite. Therefore, objective diagnostic criteria for jaw deformities must use measurements of bone architecture, not only assessments of the occlusion. Moreover, the chosen metrics must be optimal for each of the 14 possible jaw deformity diagnoses (Table 3).

The current standard considers a jaw to be deformed if 'any' cephalometric measurement deviates more than 'two standard deviations from published norms (mean). ^{7, 9, 115} This practice is flawed, for several reasons. First, the rule assumes all that cephalometric measurements are equally effective at detecting deformity. They are not. Some cephalometric measurements are better than others at identifying particular deformities.^116-118

The second problem is that the cut–off values that separate normal from deformed have been set at 2 standard deviations from the mean. Here is an example. Consider using the SNB angle to measure the anteroposterior position of the lower jaw. Assume the SNB mean is 80° with a standard deviation of 3.5°. Under the current standard, a jaw will be diagnosed as retruded if the SNB angle is smaller than 73° and protruded if the angle is greater than 87°. Under this scheme, 2.5% of the population will be deemed to have mandibular retrognathism and the same percentage prognathism. This figure comes about because, for a normally distributed population, two standard deviations encompass 95% of individuals, with half of the excluded 5% residing at the low end of the distribution, and the other half (2.5%) at the high end. If we repeat this exercise with all possible cephalometric measurements, we will conclude that all types of jaw deformities have an equal prevalence, of precisely 2.5%. This conclusion does not correspond to reality. The NHANES III study shows that in America, 13.4% of the population has an overjet greater than 5 mm, 5.7% a reverse overjet, 3.3% an open bite, 15.2% a deep bite, and 9.5% a crossbite.¹¹⁹ Different types of jaw deformities have different prevalences, all of them higher than 2.5%.

The last problem with the current standard is that it does not recognize the fallibility of the diagnostic test. No cephalometric or clinical measurement can cleanly separate normal from abnormal. Like any other diagnostic test in medicine, cephalometric and clinical measures have unique sensitivities and specificities. More importantly, they have different positive and negative predictive values when applied to a patient population.¹²⁰

Besides the above issues, there is the particular problem of diagnosing deformities of vertical maxillary position. Measuring position requires a frame of reference, and the frame of reference from which vertical maxillary position is measured is the free-edge of the upper lip (Stomium). Surprisingly, no guideline uses this standard metric.

Generalizability

The findings of this study could be used to improve the guidelines of private insurance plans, governmental plans, and those of professional organizations. We propose the following road map.

Orthognathic surgery should be defined as the surgical correction of jaw deformities, of shape, size, position, orientation, and symmetry. Orthognathic surgery is not: (1) surgery that corrects deformities of jaw integrity, like the repair of an alveolar cleft, or the reconstruction of a missing mandibular condyle; (2) the repair of a local swelling caused by a cyst, tumor, or bone dysplasia; (3) the lengthening or relocation of the jaws when the jaws are not deformed, like in maxillomandibular advancement for obstructive sleep apnea; or (4) a surgical technique. Operations like a LeFort I osteotomy, a vertical ramus osteotomy, and a sagittal split are used in orthognathic surgery. Still, they are not themselves orthognathic surgery, for these techniques can be used for other purposes (e.g., removing a tumor, or correcting TMJ internal derangement).

The criteria for orthognathic surgery should be: (1) one or both jaws are deformed, that is, the jaw configuration prevents the normal articulation of teeth, narrows the airway, or disfigures the face; (2) the deformity impairs health by impairing function, by promoting injury, or by causing or aggravating a disease; (3) there is no equally effective, less complicated treatment; (4) the surgery is appropriate for the patient; (5) the etiology of the deformity is irrelevant.

The deformity, per se, can be identified using objective physical and cephalometric measurements. However, the metrics used for these assessments must: (1) be capable of detecting the particular structural abnormality; (2) be good or excellent at assessing the specific deformity; (3) use cut-off values that are ideal separators of abnormal against normal; (4) have adequate predicted values when applied to the population; (6) come with full disclosure of the test limitations. If objective measurements cannot meet these requirements, guidelines should defer the determination of significant deformity to expert clinicians.

Guidelines should also recognize that jaw deformities can impair health by marring function, by promoting injury, or by causing or aggravating a disease. Functional impairments include (1) ineffective mastication; (2) altered speech—misarticulations and hyponasality in severe maxillary hypoplasia; (3) dysphagia or choking from poorly masticated solid food; (4) breathing problems from increased resistance to nasal airflow (seen in maxillary hypoplasia), or obstructive sleep apnea; and (5) poor function in society because of altered body image, reduced quality-of-life, or poor self-esteem.

Oral injures related to jaw deformity include (1) biting the hard palate mucosa and the lower lip in distoclusion; (2) biting the upper lip in mesioclusion; (3) biting the cheeks in posterior crossbite, (4) fracturing incisal edges in edge to edge occlusion; (5) fracturing posterior teeth from lack of anterior guidance and (6) severe dental attrition from pathologic dental contacts.

Diseases that can be caused or be aggravated by jaw deformities include (1) OSAS; (2) myofascial pain; (3) TMJ disc disorders; (4) TMJ arthritis; (5) chronic gingivitis from oral breathing.