## 4 Discussion  
It was the main scope of this narrative review to assess the quality of the available information on the treatment strategies and indications to treatment in Skeletal Class II and Class III adult borderline patients. At the present time, poor-quality data and incomplete information are available on the \"best practice regime\" that should be adopted in adult skeletal borderline patients. The small and non-homogeneous sample sizes, lack of sample size estimation, absence of similar comparison groups at the pre-treatment stage, and the variability or absence of follow-up data were some of the main shortcomings. As we expected, surgical treatment was found to better improve cephalometric skeletal values, whereas camouflage treatment resulted primarily in dento-alveolar movements both in Class II and Class III cases. Extraction treatments (both in camouflage and combined surgical treatment) were not necessarily associated with ideal values for incisor position and inclination, especially with regard to Class III borderline cases. Contrarily, clinical expertise and adoption of specific biomechanics are key factors for a successful treatment [10; 18; 29]. All studies lacked an appropriate analysis of the facial soft tissue, limiting their evaluation to sagittal cephalometric changes. Since there is wide inter-individual soft tissue variation, the use of complete 3D soft-tissue evaluation is necessary, including analysis of facial shapes and volumes, and of the soft tissue biotype and thickness, which would result in a more robust Discriminant Analysis of treatment results. Self-perceived esthetics after camouflage and surgical treatment do not seem to be significantly different, although recent improvements in surgical techniques may provide enhancement in surgical treatment outcomes. Most of the reviewed studies present outdated clinical data, primarily planned on 2D analysis, both for the surgical and for the orthodontic clinical settings. It is plausible that a new data comparison between a borderline surgical pool and comparable camouflage patients, based on a 3D quantitative and qualitative assessment, would add new insights. Several cephalometric variables are suggested to be clinically useful, such as the Wits appraisal for sagittal discrepancy, which is preferable to the SNB-angle because it relates the maxilla and mandible to the occlusal plane, independently by the craniofacial reference. Thus, any jaw rotation relative to the cranial reference plane does not affect the severity of the jaw disharmony [14; 17; 26; 28]. Skeletal convexity (N-A-Pg) and soft tissue convexity including the nose (N0-Pn-PogO) and excluding the nose (NO-Sn-PogO), should also be considered [14]. Orthognathic surgery is preferred when there is an OVJ >10 mm, a mandibular length <70 mm, Pg-Na of approximately 18 mm, and a facial height >125 mm [2]. The true vertical sub-nasal line should be adopted for soft-tissue profile evaluation because it is independent of the position of chin and nose, thus being preferable to the E-line. In borderline skeletal Class III malocclusions, the Holdaway Angle and Wits Appraisal seem to be the main cephalometric parameters to discriminate between camouflage orthodontic treatment or orthognathic surgical treatment [17; 26; 28]. However, a disparity in threshold values exists among studies, and it is probably due to different sample sizes, ethnicities, and selective parameters at baseline. Further [16], it has been suggested that the combination of the Wits Appraisal, lower incisor inclination, and inter-incisal angle are indicative of treatment selection. From the present review, it emerged that self-image perception and potential esthetic improvement should be considered as the most important parameters in treatment decisions. However, esthetic assessment tends to be poorly structured, with differences in perception between surgeons, orthodontists, and lay-people.