According to the close proximity of hyoid bone with dentofacial structures and its muscular attachments, a probable relationship between it and different types of skeletal patterns is suspected.
The aim of this study is compare the position of hyoid bone in skeletal class I and class II patients.
In this study 50 cephalograms were divided into two groups, skeletal class I (1 ≤ ANB ≤ 4) and skeletal class II (ANB > 4), with 24 and 26 patients in each group, respectively. Horizontal and vertical position of hyoid bone were evaluated. SPSS software and student t-test were used to analyze the data.
According to the results of our study, there is no statistically significant difference between the hyoid bone position in skeletal class I and skeletal class II patients.
Since the hyoid bone position is similar in skeletal class I and class II patients, the skeletal pattern is not the only determinant of the position of hyoid bone.

The individual variations in patients with skeletal class III malocclusions affect the cephalometric indices e.g., the curve of cranial base and anteroposterior displacement of nasion and the SN inclination can affect the cephalometric indices such as the ANB angle. The aim of this study was to compare some cephalometric indices in skeletal class III with skeletal class I patients as control group. Samples in this Case-control study were 65 lateral cephalometric radiographs randomly selected before the orthodontic treatment. The samples were divided into two study and control groups with skeletal class III relationship (ANB<1) and skeletal class I relationship (2)

The main purpose of orthodontic treatment is normal positioning of teeth in three dimensional plans, including the mesiodistal inclination. In this study, mesiodistal axial inclination of posterior teeth in skeletal class II was evaluated and compared with that of posterior teeth in skeletal class I. Seventy-eight panoramic radiographs for subjects between 12 to 24 years old with skeletal class I and 78 panoramic radiographs for subjects between 12 to 19 years old with skeletal class II were selected. All of the subjects were in permanent dentition with no tooth missing, no tooth extraction, no impacted tooth, and no crowding in posterior teeth. Two reference lines were established over each radiograph: the upper one passing through the most inferior point of right and left orbits lower one passing through the right and left mental foramina. After that, the long axis of teeth was traced (the image of root canal in single-rooted teeth, mean image of buccal and palatal canals in upper premolars, mean image of mesial and distal canals in lower molars, and the image of palatal canal in upper molars.). The mean values for two skelotodental classes were analyzed using T-test. The results showed that there was significant difference between (P<0.05) mesiodistal axial inclination of teeth 15, 16, 17, 25, 26, and 27 in upper jaw in skeletal class II compared with that of the same teeth in skeletal class I, which was more mesially in skeletal class II. Mesiodistal axial inclination of teeth 36, 46, and 47 in lower jaw was more mesially in class II compared with that of the same teeth in class I. For other teeth there were no significant differences between two skeletodental classes (P>0.05). The mesiodistal axial inclination of upper molars and second premolars and lower molars in class II was more mesially compared with that of the same teeth in class I.

Severe skeletal class III malocclusions usually need a combined treatment of orthodontics and orthognathic surgery. Knowing about changes occurred following such treatments lead to improve facial esthetics and better treatment results.
This study was done to determine cephalometric changes of facial soft tissue after combined treatment in patients with skeletal class III problem.
25 patients with skeletal class III discrepancy who needed a combined treatment, were selected. Changes in nasolabial angle , upper lip and lower lip to E-line distance, angle of convexity , lip-chin-throat angle and lower anterior facial height were measured before and 6 - 12 months after surgery. Changes in parameters were analyzed with Paired t-test.
Upper lip to E-line distance (P Clinical changes in the soft tissue following a combination of orthodontic treatment and orthognathic surgery in patients with skeletal class III discrepancy are significant while these changes mostly improves esthetics of patient’s facial profile.

There is little information about the diagnostic ability of SNB and Facial angles in class II malocclusion. The aim of this study was to evaluate sensitivity and specificity of SNB and Facial angle in diagnosing anteroposterior position of mandible in patients with skeletal class II malocclusion. Pretreatment cephalograms of 76 patients with skeletal class II malocclusion were assessed in this study. Sensitivity and specificity of SNB and Facial angles were determined using SPSS and ROC (Receiver Operative Characteristics) curves. Sensitivity and specificity of Facial angle were 61 and 70 percent, respectively. The corresponding values for SNB angle were 40 and 86 percent. The highest sensitivity and specificity for SNB and Facial angles related to 75.5 and 79.5 degrees, respectively. The findings showed that in diagnosing mandibular anteroposterior position of class II patients, Facial angle is more sensitive and SNB angle is more specific. Moreover, it is suggested that in cephalometric analysis, patients with Facial and SNB angles less than 79.5 and 75.5 degree respectively, be assumed to have skeletal class II malocclusion.

There are several studies to evaluate lento-skeletal changes after treatment of skeletal class 2 malocclusion with Dr Farmand's functional appliance but in non of them facial harmony has been considered. The purpose of the present study is evaluation of facial harmony in addition to dentoskeletal changes after treatment with Dr Farmand 's functional appliance. Initial and final cephalograms of eighteen treated skeletal class 2 div 1 patients have been selected. All of them had been treated with Farmand's appliance before termination of growth spurt. Each cephalogram was separately traced two times. Means of before and after treatment data were compared with paired t-test. Skeletal class 2 relationship has been successfully corrected through decreasing ANB angle (1.88±1.75, p=0.00), 66 and angle of convexity(-1.47±1.21 , p=0.00), and Also dental changes (upper incisor retrusion and lower incisor protrusion) were occurred (decrease of U1 to SN was -4.77±4.71 , p=0.00 and increase in IMPA was +3.93±2.87 ,p=0.00). Soft tissue changes involved retrusion of upper lip to E-line (-2.86±1.88, p=0.00) and decrease of upper sulcus dept (-1.55±2.04, p=0.005) and lower sulcus dept (-2.44±1.85 ,p=0.00) which played an important role in improvement of facial harmony . Lower lip was placed more anteriorly relative to H-line (1.37±1.48 p=0.001) which is not desirable in profile harmony. Dr Farmand's functional appliance is effective in treating skeletal class 2 patients by producing skeletal as well as dental improvement. Soft tissue harmony also is improved but final position of lower lip must be regarded more carefully.

The facial esthetics after orthodontic treatment and orthognathic surgery may be affected by the patient’s natural head position. The purpose of this study was to evaluate the natural head position for the three skeletal classes of malocclusion. Our sample consisted of 102 lateral cephalometric radiographs of patients aged 15 to 18 years; class I (n=32), class II (n=40) and class III (n=30). Nine landmarks of the craniofacial skeleton and three landmarks of the cervical vertebrae were determined. Variables consisted of two angles for cervical posture (OPT/Hor and CVT/Hor), three angles for craniofacial posture (SN/Ver, PNS-ANS/Ver, and ML/Ver) and five for craniofacial angulation (SN/OPT, SN/CVT, PNS-ANS/OPT, PNS-ANS/CVT, ML/CVT). The data were analyzed statistically using ANOVA and post hoc tests. PNS-ANS/Ver and SN/Ver differed significantly (p<0.05) among the three groups. There were no significant differences between class I and class II malocclusions for the indicator angles of cranial posture except for ML/Ver. The SN/CVT was significantly different for class I compared to class III patients. A head posture camouflaging the underlying skeletal class III was observed in our population. A more forward head posture was observed in skeletal class III participants compared to skeletal class I and II and that class III patients tended to incline their head more ventral compared to class I participants. These findings may have implications for the amount of jaw movements during surgery particularly in patients with a class III malocclusion.

A main problem in the treatment of patients with skeletal Class III malocclusion is making the decision whether only orthodontic therapy or a combination of orthodontic therapy and surgery will solve the problem، which usually has to be made at a young age. The aim of this study was to evaluate the relationship between the frontal sinus surface area and size of mandible in adults to assess the possibility of the use of this anatomic structure as an indicator for prediction of mandibular growth in future studies. In this cross-sectional study، 71 cephalograms from a private orthodontic clinic were analyzed، consisting of 20 adults with skeletal Class I، 19 adults with skeletal Class II and 32 adult patients with skeletal Class III malocclusions of both male and female subjects. The surface area of the frontal sinus (mm2)، SNA، SNB، ANB، Wits، overjet، saddle angle، gonial angle، facial angle، mandibular length and body length were assessed on cephalograms. Pearson’s correlation test was used to assess the relationship between frontal sinus area and other cephalometric indices at a significant level of 0. 95. The results revealed significant direct relationships between frontal sinus size and SNB، gonial angle، facial angle، body length and mandibular length and inverse relationships with ANB، Wits and overjet. The frontal sinus area showed the highest correlations with mandibular length (r = 0. 69) and body length (r = 0. 60) (p value < 0. 0001). The frontal sinus surface area can possibly be used as an additional indicator for predicting the final mandibular size، with a valuable role in the diagnosis and treatment planning.

Nasopharyngeal space is estimated from a point on the posterior part of the soft palate till the nearest point on the wall of the pharynx and the aim of the present study was to study the nasopharyngeal indices in nasal breathers with class I and III malocclusions. This was a descriptive analytical study done by the case - control method on 35 lateral cephalometries of patients with skeletal Class III malocclusion as the study group and 30 lateral cephalometries of patients with skeletal Class I malocclusion as the control group. The population under study included patients referring to the orthodontic clinic and their age range was between 10 and 20 years. The lateral cephalometric radiographies were traced and data was analyzed using coefficient relation and t test. The bony height of the nasopharyngeal space had a statistically significant positive relationship with the anterior facial height. The bony area of nasopharyngeal space had a significant positive relationship with the anterior and lower facial height. There was no significant difference between the bony dimensions of the nasopharyngeal space and nasopharyngeal and oropharyngeal airway of the two groups. There was no significant difference between nasopharyngeal area parameters in skeletal Class I and Ill malocclusion. In nasal breather with skeletal Class III malocclusion, dimensions of nasopharyngeal area have no significant effect on facial growth pattern.

For many years, the conventional approach to orthognathic surgery which was orthodontic treatment prior to orthognathic surgery has been the accepted method of treatment for skeletal class III malocclusion patients. This review compared the dentoskeletal stability of treatment results between conventional orthognathic surgery methods with presurgical orthodontic treatment and surgery-first approach in skeletal class III patients. The study protocol was based on Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement for systematic review and meta-analysis. Electronic and manual searches for literature since 2011 were conducted. PubMed and Medline databases were accessed. Data extraction and analysis were performed by two independent individuals. Seven studies out of hundred-fourteen articles met the inclusion criteria and were selected for qualitative analysis. The included studies were 494 patients with skeletal class-III malocclusion. Stability of treatment was compared between surgery-first approach and conventionally treated patients. The statistical analysis confirmed that surgery-first approach did not show more stability compared with presurgical orthodontics. The surgery-first approach shortened the overall treatment duration. However, more skeletal stability in conventional treatment was assessed. Both surgery-first approach and conventional treatment with presurgical orthodontics resulted in favorable skeletal changes in class-III malocclusion patients. Moreover, these findings should be discussed further due to the variety of study designs, outcomes and biases. Current evidence in this field still needs to be expanded. The authors wish to see more well-designed randomized controlled trials with long-term follow ups to confirm the results.