Skeletal balance, functional occlusion, and facial harmony are common goals in orthodontics and orthognathic surgery. However, the boundary line for the decision between orthodontic and surgical treatment remains very controversial in adult borderline patients. Up to 10% of orthodontically treated patients are borderline and may have been treated either way (both with camouflage and orthognathic surgery) ^[1]. Cassidy ^[2] defines “borderline cases” as those patients who were similar in respect to the characteristics on which the orthodontic/surgical decision appeared to have been based. The decision-making process is influenced by different variables, such as facial esthetics, patient desires, values and cultural differences, orthodontist background and preferences, surgical expertise, and financial considerations ^[3][4]. The introduction of 3-Dimensional (3D) imaging and computer-aided surgical planning have improved accuracy and prediction in surgical outcomes ^[5][6]. Moreover, they have enhanced new protocol regimes that are promising in that they can potentially reduce the overall treatment time and obtain immediate improvement in facial esthetics, greater patient satisfaction, and improved cooperation during postoperative orthodontic treatment ^[7][8]. Conversely, the recent application of Temporary Anchorage Devices (TADs) and 3D technologies have significantly improved the orthodontic field by facilitating dental movements that were previously only achievable by means of orthognathic surgery ^[9]. Complex malocclusions can be resolved through orthodontic treatment by means of TADs, driving the more complicated movements such as molar intrusion, distalization, and molar protraction ^[9]. However, according to a recent systematic review on Class III camouflage orthodontic treatment by Sakoda et al., most of this recent information is derived from case reports and expert opinions, which lack stronger evidence and predictable clinical reproducibility ^[10]. In addition, recent interest in patient satisfaction during health care provision has grown significantly. Patients’ perceptions and expectations have become increasingly important in justifying health services delivery and ensuring overall health care quality ^[9]. A recent systematic review concludes that final esthetic outcome, perceived social benefits, type of orthognathic surgery, sex, and changes in patient self-concept during treatment were associated with satisfaction. Treatment length, sensation of functional impairment and/or dysfunction after surgery, and perceived omitted information about surgical risks were associated with patient dissatisfaction ^[11].

Historically, Proffit and Ackerman introduced the “envelope of discrepancy” concept. The Profitt diagram illustrates the quantitative relationship of three basic treatment possibilities for a skeletal discrepancy. When a moderate discrepancy exists and there is no growth potential, orthodontic camouflage could be applied by displacing the teeth to obtain proper function despite the jaw relationship, which produces a dental compensation for the skeletal discrepancy. However, the envelope outlines the sagittal limits of hard tissue changes towards an ideal occlusion, but does not include transversal limits in skeletal discrepancy, soft tissue evaluation and patients’ complaints, resulting in an incomplete method of treatment decision in borderline cases ^[4][12].

It is suggested that orthodontic camouflage of skeletal malocclusions would have acceptable results if there were an average or short facial pattern, mild anteroposterior jaw discrepancy, dental crowding lower than 4–6 mm, normal soft tissue features (nose, lips, chin), and no transverse skeletal problems. Poor results would be expected with the following: a long vertical facial pattern, moderate or severe antero-posterior jaw discrepancy, dental crowding greater than 4–6 mm, exaggerated facial features, and a transverse skeletal discrepancy. As a rule, skeletal Class II conditions are more suitable for a camouflage correction compared with those of skeletal Class III ^[12][13].

At present, few studies have compared the outcomes between surgical and orthodontic camouflage treatments for adult skeletal borderline patients. Previous research has adopted different hard and soft-tissue cephalometric parameters both in Class II and Class III skeletal borderline to define criteria for pre-treatment selection. However, no consensus was obtained concerning the best assessment method. The current data are mostly derived from retrospective studies with moderate to low scientific evidence. No randomized clinical trials have been undertaken comparing the surgical and the orthodontic camouflage options, owing to the difficulty in patient recruitment, for ethical reasons. Prospective studies are rare due to the excessive cost and study length. Finally, a few studies have reported long-term follow up that could evaluate which treatment modality would be more stable overtime ^[14].

2. Class II

There are two treatment options in Class II borderline post-pubertal correction: orthodontic camouflage with or without genioplasty and orthodontic-surgical correction through single jaw or bimaxillary surgery. In orthodontic camouflage treatment, the goal is to mask the skeletal discrepancy through dental compensation. When extractions are required, they are generally done in the upper arch (first premolars) to correct the overjet and/or the protrusion of the upper incisors ^[14]. In addition, the use of functional appliances, advocated in younger patient to enhance mandibular growth modification, have been reported in adult patients to change dental position only ^[15][16]. Conversely, orthodontic–surgical treatment aims to correct the underlying skeletal deformity. Dental decompensation is a fundamental prerequisite in the orthodontic-first approach, while with a surgery-first protocol, it should be considered an absolute objective of post-surgery orthodontics for treatment stability. Previous experience suggests that there are flaws in the process of selecting treatment options ^[16]. According to the available literature, there are no clear guidelines on the best treatment approach for Class II adult borderline patients ^[14].

Study Design and Treatment Interventions

Concerning skeletal Class II patients, researchers found 6 non-randomized clinical trials (N-RCT) and one systematic review (Table 1). All studies are retrospective cephalometric studies which compare orthodontic-only intervention and orthodontic–surgical intervention through skeletal, dental, and soft tissue cephalometric changes from baseline to the end of treatment (Table 2). Some studies added dental cast measurements and patient and/or clinician retrospective evaluation of outcomes of facial soft tissue by the clinician and/or patient satisfaction. Four studies ^{[2][15][17][18]} reported a variable period of follow-up. The most represented malocclusion was Class II Division 1, and the primary surgical intervention undertaken was mandibular advancement. Compared to other surgery procedures, bimaxilary surgery was reported as a treatment option in very few studies. In a 1992 retrospective study, Proffit et al. ^[15] compared the short-term (1-year post treatment) outcomes (33 patients treated with orthodontics-only, and 57 with surgery and orthodontics) by evaluating whether the final measurement values fell within the normal range, as well as the quantitative amount of correction produced relative to an “ideal” value. Also, a group of judges rated esthetic changes from frontal and profile photographs. Whether or not most patients in both groups achieved acceptable changes in the occlusal parameters, overall surgical treatment resulted in greater improvement for most criteria (cephalometric skeletal, dental, and soft tissue); in particular, a significantly greater percentage of the “ideal” goal was achieved for the ANB Angle, maxillary incisor position, soft tissue A-B difference, and overjet (OVJ). Esthetic changes determined by orthodontic treatment were small (ratings remained unchanged), whereas those determined by surgical treatment were substantial, especially in patients with the lowest initial ratings. It is important to point out that in this study no attempt was made to match the groups; at baseline, the orthodontic group presented less severe skeletal conditions and a more pleasant facial soft tissue. In addition, orthodontic treatment strategy and mechanics were different among the groups, and this could account for different outcomes at the end of treatments. Camouflage treatment seems more effective in those patients who initially have pleasant facial esthetics, as orthodontic treatment alone can be accomplished without detriment to facial esthetics. The more severe the mandibular deficiency, the greater the OVJ and the poorer the facial esthetics, the more likely it is that the patient benefits from surgery. In 1993, Cassidy et al. ^[2] compared long-term effects of orthodontic and surgical treatment. By using a discriminant analysis, they identified two homogeneous groups of patients with moderately severe skeletal Class II malocclusion, morphologically similar, thus susceptible both to orthodontics-only camouflage treatment (27 subjects, with/without extractions) or mandibular advancement (28 subjects). They evaluated skeletal and dental changes through lateral cephalograms and dental cast analysis, assessment of profile esthetics, and temporomandibular functionality. Results showed no significant differences in patient profile evaluation and no significant differences in craniomandibular functionality and incisor stability. At recall (7.1-years after orthodontic treatment and 4.7 years after surgery), the camouflage treatment group’s relapse was minor and concerned incisor uprighting and a loss of some overbite (OVB) correction. Decision analysis and utility scales were used to calibrate patient preference by measuring the risk that borderline patients were willing to assume to achieve a desired outcome; it was found that orthodontic treatment had a better payoff, whereas surgery was preferable in more severe skeletal discrepancies. In a 2003 N-RCT, Mihalik et al. ^[17] evaluated long-term (from 1-year up to >5 years) skeletal and soft tissue changes, occlusal stability, and patient satisfaction with treatment in a sample of 31 adult patients treated with orthodontic camouflage (involving dental extractions) or orthognathic surgery. Data collection included cephalometric variables, dental casts, intraoral and extraoral photographs, self-evaluation forms, and satisfaction questionnaires. Results showed that OVB change was similar between the groups, and it was related to incisor over-eruption and post-treatment incisor irregularity. Surgery patients were twice as likely to have a long-term increased OVJ, which was due to dental compensation related to late soft tissue changes and post-surgery skeletal remodeling. In this study, camouflage patients have, in general, less severe problems than those treated surgically, as well as fewer functional and/or temporomandibular joint problems. The greater amount of change produced by surgery contributes to the greater prevalence of long-term changes in surgery patients. The overall satisfaction with treatment was comparable within groups, but patients who underwent mandibular advancement were significantly more positive about their appearance. Mihalik, therefore, suggested that the ideal patient for camouflage should have good initial facial esthetics, with an increased OVJ related to maxillary incisor protrusion rather than skeletal mandibular retrusion. A greater mandibular deficiency and a large OVJ have an increased need for surgery in order to obtain satisfactory clinical correction. In conclusion, the way that patients perceive the severity of their problem is a key in the decision-making process to elect for surgery rather than a camouflage plan or no treatment. In a 2004 N-RCT by Ruf et al. ^[19] the efficacy of the Herbst appliance (a fixed Class II corrector), used in 23 adult patients with borderline skeletal Class II Division 1, was compared to a similar group of 46 adult patients treated with non-extraction mandibular advancement by means of bilateral sagittal split osteotomy (BSSO). The surgery group showed greater changes in mandibular advancement, with reduction in SNB, SNPg, ANB, and Wits Appraisal; increased anterior facial height, profile convexity reduction, retrusion of upper lip, and Class II molar correction, whereas SNA changes were comparable for both groups. As expected, these changes showed the same direction except for the mandibular plane angle (increased in the surgery group) and the posterior facial height (smaller in the surgery group). The data suggest that, whereas occlusion can be successfully corrected by the means of a Herbst Appliance, chin projection and facial esthetics cannot. If the patient’s main goal is to greatly improve facial profile, BSSO or advancement genioplasty only (if the main complaint is chin prominence) are a better option. The absence of a follow-up and over-representation of women in both samples are some important limits of this study. Moreover, it would have been useful to compare these results to those from a third group of patients, treated with an orthodontic camouflage plan involving dental extraction.

3. Class III

3.2. Class III

Borderline Class III Camouflage treatment can be carried out by different approaches and may include dental extractions (most commonly lower premolars and lower incisors), distalization of the mandibular dentition, and use of Class III intermaxillary elastics ^[10]. Successful camouflage treatment consists of dentoalveolar compensations, which mask the underlying skeletal problem while allowing for an improvement in occlusion, function, and esthetics. On the other hand, surgical–orthodontic treatment varies according to skeletal sagittal and vertical discrepancy. It could consist in one-jaw surgery: mandibular set-back or maxillary advancement, or in bimaxillary surgical procedures. Genioplasty could be combined with either surgery. The main objective of combined orthodontic and orthognathic surgery treatment is to correct the skeletal discrepancy, establish optimal function, and improve facial balance and harmony. This often involves the correction of the main dental and skeletal variables to a range of accepted cephalometric values. The surgical-first protocol, when indicated, has recently been favored over the orthodontic-first protocol in Class III conditions because it is more stable and psychologically favorable for the patient ^[7][8].