***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: OBJECTIVE To compare the treatment effects of maxillary anterior teeth retraction with mini-implant anchorage in young adults with Class II division 1 malocclusion undergoing extraction of the maxillary first premolars with similar patients treated by a fixed functional appliance . MATERIAL S AND METHODS Thirty-four young adult female patients ( mean age 16.5 ± 3.2 years , overjet ≥ 6 mm ) with a Class II division 1 malocclusion were divided into two groups : group 1 ( G1 ) , in which overjet correction was obtained with a fixed functional appliance ( FFA ) , and group 2 ( G2 ) , in which upper first premolars were extracted , followed by space closure with MIs as anchor units  . Dentoskeletal and soft tissue changes were analyzed on lateral cephalograms taken before ( T1 ) and after ( T2 ) correction of the overjet . RESULTS Both methods were useful in improving the overjet and interincisal relationships . Extrusion and mesial movement of the lower molar , together with lower incisor proclination , were noted in G1 . G2 showed distalization and intrusion of the upper molar . The nasio-labial angle became more obtuse in G2 , while lower lip protrusion was seen for G1 . CONCLUSIONS The two treatment protocol s provided adequate dental compensation for the Class II malocclusion , but did not correct the skeletal discrepancy . There were significant differences in the dental and soft tissue treatment effects between the two treatment protocol INTRODUCTION The esthetic impact of the soft-tissue profile might play a major role in deciding on premolar extraction or non extraction treatment , particularly in borderline patients . The purpose of this study was to compare the esthetic impact of extraction and non extraction therapy on Korean patients . METHODS Panels of 50 dentists and 50 laypersons evaluated r and omly presented pretreatment and posttreatment soft-tissue profiles of 50 extraction and 50 non extraction patients .  As subjects in this study , borderline patients were selected based on their initial diagnostic records . Two panels were asked to compare the pretreatment and posttreatment profile tracings and to quantify their perceptions of the esthetic impact of treatment change using a visual analog scale . RESULTS Premolar extraction patients showed greater improvement in facial profile compared with non extraction patients , regardless of the panel . Based on the results of regression analysis to determine the degree of lip protrusion at which the retraction that commonly follows premolar extraction would be needed , the intersection was about 3.0 mm behind the Ricketts ' E-line ; this is far behind the Korean norm . CONCLUSIONS The results indicate that premolar extraction is more beneficial than non extraction treatment in terms of facial profile improvement in Korean borderline patients BACKGROUND No r and omized controlled trial has tried to compare treatment outcomes between the sliding en-masse retraction of upper anterior teeth supported by mini-implants and the two-step sliding retraction technique employing conventional anchorage devices . OBJECTIVE To evaluate skeletal , dental , and soft tissue changes following anterior teeth retraction . DESIGN AND SETTING Parallel-groups r and omized controlled trial on patients with class II division 1 malocclusion treated at the University of Al-Baath Dental School in Hamah , Syria between July 2011 and May 2013 . PARTICIPANTS One hundred and thirty-three patients with an upper dentoalveolar protrusion were evaluated and 80 patients fulfilled the inclusion criteria . R and omization was performed using computer-generated tables ; allocation was concealed using sequentially numbered opaque and sealed envelopes . Fifty-six participants were analysed ( mean age 22.34 ± 4.56 years ) . They were r and omly distributed into two groups with 28 patients in each group ( 1:1 allocation ratio ) . INTERVENTION Following first premolar extraction , space closure was accomplished using either the en-masse technique with mini-implants or the two-step technique with transpalatal arches ( TPAs ) . MAIN OUTCOME MEASURE The antero-posterior displacements of upper incisal edges and upper first molars were measured on lateral cephalograms at three assessment times . Assessor blinding was employed . RESULTS A bodily retraction ( -4.42 mm ; P < 0.001 ) with a slight intrusion ( -1.53 mm ; P < 0.001 ) of the upper anterior teeth was achieved in the mini-implants group , whereas upper anterior teeth retraction was achieved by controlled palatal tipping in the TPA group . CONCLUSIONS When retracting anterior teeth in patients with moderate to severe protrusion , the en-masse retraction based on mini-implants anchorage gave superior results compared to the two-step retraction based on conventional anchorage in terms of speed , dental changes , anchorage loss , and aesthetic outcomes Objective : The objective of this study was to establish whether and how premolar extraction affects the soft tissue profile and incisor inclination in patients with Angle Class II , Division 1 malocclusion . Our primary intention was to identify differences between patients who had four premolars extracted and those who had only two upper premolars removed during camouflage treatment .  Our control group consisted of patients with an Angle Class II , Division 1 treated without extraction s.  Material s and Methods : These patients ’ lateral cephalograms were cephalometrically analyzed before and after treatment . Computer-assisted analysis of the data using Onyx Ceph ® was followed by a single-factor variance analysis ( one-way ANOVA ) . Results : Our results demonstrate that patients who have undergone camouflage treatment exhibit significantly more retruded upper central incisors than those with extraction s in both jaws , and that their upper incisors are highly significantly more retruded and their m and ibles significantly more retrognathic than those of patients who have not undergone extraction therapy . Conclusion : We did not observe that the patients ’ profiles did become worse after extraction therapy . ZusammenfassungZiel : Es soll dargestellt werden , ob und wie sich eine Prämolarenextraktion auf das Weichteilprofil und die Schneidezahnneigung bei Patienten mit Angle-Klasse II,1 auswirkt . Vor allem sollen Unterschiede zwischen Patienten , bei denen vier Prämolaren extrahiert wurden , und Patienten , denen i m Rahmen einer Camouflage-Beh and lung nur zwei Prämolaren i m Oberkiefer entfernt wurden , ermittelt werden . Als Vergleichsgruppe dienen Patienten mit einer Angle-Klasse II,1 , die ohne Extraktionen beh and elt wurden . Material und Method ik : Die Fernröntgenseitenbilder dieser Patienten wurden vor und nach der Beh and lung kephalometrisch ausgewertet . I m Anschluss an die computergestützte Auswertung der Date n mit Onyx Ceph ® erfolgte eine einfaktorielle Varianzanalyse ( Oneway ANOVA).Ergebnisse : Die Ergebnisse zeigen , dass Patienten mit Camouflage-Beh and lung nach Therapie signifikant retrudierter stehende obere mittlere Schneidezähne als Patienten mit Extraktionen in beiden Kiefern haben und dass sie höchst signifikant retrudierter stehende obere Schneidezähne sowie signifikant retrognather liegende Unterkiefer als Patienten ohne Extraktionstherapie aufweisen . Schlussfolgerung : Eine Profilverschlechterung nach Extraktionstherapie konnte nicht nachgewiesen werden Soft-tissue profiles were examined in 160 orthodontic patients treated with removal of four first premolars . Records of 10- to 30-year-old patients were selected at r and om from five sources : patients treated by Charles H. Tweed on file at the Tweed Foundation , patients treated with the Begg technique by the Kesling-Rocke group , patients from two practice s with pretorqued , preangulated edgewise appliances , and patients with premolars enucleated at an early age . The mean changes for the total sample included an increase of 5.2 degrees in the nasolabial angle , and retraction of the upper and lower lips 3.4 and 3.6 mm to the E line , respectively . For different measurements , between 5 % and 25 % of the sample had values indicating more protrusive lips after treatment . In comparisons among groups , the Tweed patients generally exhibited the greatest lower lip retraction . When profile changes were compared to values representing normal ( or " ideal " ) facial esthetics , it was evident that extraction of four first premolars generally did not result in a " dished-in " profile . Approximately 10 % to 15 % of cases could be defined as excessively flat after treatment . Eighty percent to 90 % of patients treated by extraction of four first premolars had soft-tissue measurements that suggested the profile was improved by treatment or remained satisfactory throughout treatment INTRODUCTION A prospect i ve r and omized study was design ed to compare the skeletal , dental , and soft-tissue profile changes in Class I borderline patients treated with extraction and non extraction  by means of the air-rotor stripping ( ARS ) technique and to compare the treatment times . METHODS Twenty-six borderline patients with balanced and orthognathic facial profiles were r and omly divided into 2 groups . In the first group , 13 subjects with a mean age of 18.1 + /- 3.7 years and mean maxillary and m and ibular crowding of 5.7 + /- 1.5 and 5.9 + /- 1.4 mm , respectively , were treated by removal of 4 premolars with minimum anchorage . In the second group , 13 subjects with a mean age of 17.8 + /- 2.4 years and mean maxillary and m and ibular crowding of 5.0 + /- 1.3 and 5.9 + /- 1.3 mm , respectively , were treated with ARS .  Lateral cephalometric radiographs and dental models taken before and after treatment were evaluated . RESULTS The initial skeletal , dental , and profile characteristics of both groups were similar . In the first group , the maxillary and m and ibular incisors were slightly retracted , whereas lip positions did not change . In the non extraction group , maintenance of maxillary incisor position , slight protrusion of the m and ibular incisors and the upper and lower lips were observed at the end of treatment . The nasolabial angle decreased significantly . Because of postpubertal growth of the nose and the chin , the lips appeared slightly retrusive after extraction therapy , whereas lip protrusion was compensated in the non extraction group . The main soft-tissue profile differences between the 2 groups were 1 to 1.5 mm more retruded upper and lower lip positions in the extraction patients , but both groups had well-balanced and desirable facial esthetics with all profile measurements within normal limits . Non extraction therapy with ARS reduced treatment time by 8 months . CONCLUSIONS Both extraction and ARS combined with non extraction therapies are effective treatment alternatives for Class I borderline patients with good facial profile and moderate dental crowding This investigation was design ed to compare the esthetic effects of extraction and non extraction treatments .  Panels of 58 laypersons and 42 dentists evaluated r and omly presented pre- and posttreatment profiles of 70 extraction and 50 non extraction Class I and II Caucasian patients . The sample s were similar at the outset ; however , at the end of treatment , the extraction patients ' faces were , on average , 1.8 mm " flatter " than the faces of non extraction subjects . The flatter faces were preferred by both panels , dentists more so than laypersons . In general , non extraction treatment was seen as having little effect on the profile , whereas the perceived effect of extraction treatment was a statistically significant function of initial soft tissue protrusion-the greater the initial protrusion , the greater the benefit . The point at which a reduction in protrusion produces a perceived improvement was explored by way of regression analysis . Both panels saw extraction as being potentially beneficial when the lips were more protrusive than 2 to 3 mm behind Ricketts ' E-plane . It is concluded that extraction treatment can produce improved facial esthetics for many patients who present with some combination of crowding and protrusion Aim : It was the aim of this clinical study to compare the skeletal and dentoalveolar effects as well as those on the profile of three different treatment approaches in Class II patients ( camouflage orthodontics , dentofacial orthopedics , and combined orthodontic and surgical treatment ) . Patients and Method : Our study cohort consisted of 60 young adults presenting a skeletal Class II , Division 1 malocclusion : 20 patients whose overjet was reduced by camouflage following premolar extraction , 20 patients whose occlusions were corrected by placement of a fixed functional orthopedic appliance , and 20 who underwent orthognathic surgery ( bilateral sagittal split osteotomy of the m and ible without genioplasty ) .  We documented the therapeutic progress using cephalometry . Results : Each patient group achieved a reduction in overjet via their respective treatment . While no treatment-related changes in the maxillary area were assessable , the effects on the m and ible differed . We observed advancement of the bony chin and an increase in m and ibular length in the sagittal-diagonal dimension in the surgical and functional orthopedic groups . However , the extent of the treatment-related changes was significant only in the group of patients that had undergone orthognathic surgery .  Only the surgical group presented changes in vertical relationships . Incisor repositioning as an outcome of the respective treatments differed fundamentally , with those in the surgical group revealing significant protrusion of the upper incisors . The maxillary incisors were retruded and m and ibular incisors proclined in the functional orthopedic group , whereas the upper and lower incisors both retruded significantly in the extraction group . Softtissue remodeling bore no linear relationship to treatment-induced skeletal and dental effects . Still , orthognathic surgery led to the most marked profile changes . Treatment using fixed functional orthopedic appliances reduced the convexity of the soft-tissue profile at least moderately . Camouflage orthodontics , on the other h and , result ed in an increase in the nas 
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Retrusion of the upper and lower lips were also verified , with less retraction of the lower lip in 2-premolar extraction groups .
When Class II division 1 malocclusion is treated with premolar extraction s , the NLA increases and the lips are retracted .
However , there is less retraction of the lower lip in the 2-maxillary premolar extraction protocol