The success of orthodontic treatment is closely related to facial appearance improvement. A balanced soft tissue profile is an important factor to achieve during orthodontic treatment . This type of malocclusion is frequently reported as the irregularity that alters facial proportions, symmetry, and balance. Thus, correction of facial features will lead not only to facial profile correction, but also to long-term psychosocial well-being of patients . Orthodontic treatment modifies the position, length, and relation between skeletal and dentoalveolar structures, and subsequently, facial expressions and esthetics are modified and enhanced (these effects are shown in Figs. 1 and 2). Facial harmony can often be described as dependent on morphological relations, and proportions between three facial structures: nose, lips, and chin . The facial profile consists of five facial prominences: the forehead, nose, lips, chin, and submental-cervical region. The interrelationship between these various components of the facial profile plays an important role in the perception of facial esthetics . Relations between these structures are presented using angular measurements in the photogrammetric analysis in this investigation.
The nasomental angle (N-Prn-Pg), or nasal prominence angle, is in the range between 20 and 30 degrees in Class I patients , whereas in Class II Patients, the value is increased. In this study, the nasomental angle showed a statistically significant decrease in the non-extraction group of patients, although it was not clinically relevant (-1º). This favorable outcome could have occurred as a result of anterior movement of the soft tissue point pogonion (Pg). This movement promoted positive changes on the soft tissue profile and was reported also by doRego et al. .
Significant improvements in facial profile were recorded in the first group of patients (treated with the Herbst appliance without extractions). In particular, the nasolabial (Cm-Sn-Ls) and mentolabial (Li-Sm-Pg) angles showed significant increase after the treatment. The nasolabial angle (Cm-Sn-Ls) can be changed with both orthodontic and surgical treatment. It plays an important role in a facial profile appearance, and in some cases, it can be used as a guideline for the extraction decision. According to a study by Bergman , regardless of the type of treatment needed for the patients (whether it is surgical or orthodontic correction), this angle should be 102 ± 8 degrees. After orthodontic treatment, this angle increased significantly, since the upper lip moved backwards and downwards, and its prominence has been decreased, mostly due to retrusion of the upper incisors. The nasolabial angle also showed a significant increase in the second group of patients, treated with premolar extractions. The increase of this angle was reported also by Iared et al.  who confirmed that a backward movement of the upper lip occurred because of orthodontic treatment with extraction of premolars.
The mentolabial angle (Li–Sm–Pg) also showed great variability. A more pronounced mentolabial angle can be seen in Class II and vertical maxillary deficiency cases. In both groups of patients, this angle has been increased after the treatment, as a result of achieving a balanced dentoalveolar relation, due to upper incisors retrusion .
Significant improvements in facial profile concerning chin and upper lip balance were recorded in the first group of patients. In particular, the angle determining the projection of the upper lip to the chin (N-Pg-Ls), as well as the upper lip angle (Sn–Ls–Pg), showed a significant reduction. This result is related to a less pronounced upper lip. The value of these angles showed a statistical significance in the non-extraction group, given the fact that point Pg moved forward, while point Ls moved backward, which is an expected result of treatment with the Herbst appliance . Moreover, this is also a result of decreasing of the upper lip prominence, as a consequence of upper incisors retrusion, in a ratio of 1:3. Many authors confirmed the relation between upper lip position and upper incisors retrusion, in the ratio of 1:3 [25, 26]. Furthermore, esthetical modification depends on upper and lower incisors position, as well as on the change of the position and development of the lower jaw .
The angle N-Pg-Ls showed a statistically significant difference comparing the two groups of patients. The lower lip is the adjacent esthetic subunit to the chin, and its features play an important role in determining facial esthetics in the lower third of the face . As such, the prominence of the lower lip may influence the perception of chin prominence and thus the overall management plan in terms of camouflage vs orthognathic surgery and extraction vs non-extraction decisions [22, 29, 30].
Therefore, a change in the lower lip position and consequent change in the lip/chin relation influences facial esthetics, as these entities determine the profile type. As mentioned, the facial profile in patients with this type of malocclusion is altered and considered unattractive before the treatment. As a result of improvement of these proportions and of the profile, the esthetic perception is changed from unattractive to attractive, which is one of the main reasons why patients seek orthodontic treatment .
The profile angles are used to assess convexity or concavity of the facial profile. The angle of facial convexity excluding the nose or facial angle (G-Sn-Pg) is supposed to be in a range of 165–175 degrees . This angle is decreased in Class II and increased in Class III. In our sample, all patients had a decreased value of this angle before the treatment. After the treatment, the facial angle was increased in both groups of patients, however, not significantly. The favorable outcome, not statistically significant, yet esthetically relevant, was the profile strengthening caused by reduction of facial convexity, which is previously one of the main reasons of patients’ dissatisfaction .
Godt et al.  also described this angle as one of the most important in determining patient’s skeletal class.
The angle of facial convexity including the nose or total facial angle (N-Prn-Pg) showed a statistically significant difference comparing the two groups of patients. This result can also be related to the previously mentioned effect of the Herbst appliance - forward movement of the point Pg .
It is of high importance to analyze the patients’ profile before the treatment, in order to establish the most desirable treatment results. In some cases, there are limitations in treatment outcomes induced by facial features, their proportions and expressiveness (for instance, size and position of the chin and nose prior to treatment). Many authors compared different orthodontic treatments to establish if and how they influence the facial esthetics and overall appearance. Some of them found no statistical significance between different treatment protocols and improving the facial esthetics [22, 30]. Nevertheless, many factors should be carefully evaluated before starting the orthodontic treatment . At the end of the treatment, patients show satisfaction with their facial esthetic improvement, mostly judged by the influence of the environment and contemporary beauty canons.