***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 mesial movement of upper first molars during maxillary canine retraction using a pre-adjusted edgewise appliance provided by anchorage reinforcement and a transpalatal arch or mini-screw implant . Design R and omized clinical trial . Setting Department of Orthodontics and Dentofacial Orthopedics , Armed Forces Medical College , Pune , India . Subjects and methods From a cohort of subjects requiring the extraction of both upper first premolars and pre-adjusted edgewise appliances to correct their malocclusion , a total of 30 were r and omly allocated to receive two different forms of anchorage reinforcement : Group A – receiving mini-screw implant and Group B – receiving a transpalatal arch Group A subjects received titanium mini-screw implants placed at the start of treatment between the maxillary second premolar and maxillary first molar . Maxillary second premolars were secured to the mini-screw implants using of 0·010-inch stainless steel ligature wire . Group B subjects received a custom-made transpalatal arch which was soldered to maxillary first molar b and s. Active canine retraction was initiated in both groups on placement of a 0·019 × 0·025-inch stainless steel archwire using nickel titanium closed coil springs . Outcome measures Mesial movement of the upper first molars as measured on pre- ( T1 ) and post-treatment ( T2 ) lateral skull radiographs . Results The results showed that in Group A the mean mesial movement of the first molars between T1 and T2 was 0·0 mm ( SD 0·02 ; P = 0·90 ) , whereas in Group B there was a mean forward movement of the first maolars of 2·48 mm ( SD 0·71 ; P<0·001 ) . Conclusion In this trial , mini-screw implants placed prior to levelling and aligning were able to provide absolute anchorage during maxillary canine retraction , in contrast to a transpalatal arch Flaws in the design , conduct , analysis , and reporting of r and omised trials can cause the effect of an intervention to be underestimated or overestimated . The Cochrane Collaboration ’s tool for assessing risk of bias aims to make the process clearer and more The aim of this trial was to evaluate whether a Nance or Goshgarian palatal arch was most effective for prevention of mesial drift , distal tipping , prevention of mesio-palatal rotation of the upper first permanent molars , and patient comfort and ease of removal .  Patients were recruited from a district general hospital and a specialist orthodontic practice and r and omly allocated to a Goshgarian ( n = 29 ) or a Nance ( n = 28 ) group . Pre-treatment study models ( T1 ) were taken followed by the placement of the palatal arch , premolar extraction s , and upper and lower fixed appliances . The clinical end point was 6 months ( T2 ) , at which time , an impression for an upper study model was taken . The amount of upper first permanent molar mesial movement , distal tipping , and mesio-palatal rotation was measured by scanning T1 and T2 study models and then using a software program to calculate molar changes . In addition , the patients recorded their discomfort scores using a seven-point Likert scale at each recall visit . Forty-nine patients ( 86 per cent ) completed the trial . t-tests were used to compare molar movements between the Goshgarian and Nance palatal arch groups . There were no statistically significant differences between the palatal arches in terms of prevention of mesial drift or distal tipping ( P > 0.05 ) . There was a statistically significant difference in the amount of molar rotation between the arch types , with both exhibiting some disto-palatal rotation even though they were not activated for this movement . The Goshgarian palatal arch produced marginally more disto-palatal rotation than the Nance arch ( P = 0.02 ) , although this may not be considered clinical ly significant . A Mann-Whitney test revealed that there was also a statistically significant difference in pain scores between the Goshgarian and the Nance arch , with the latter being associated with more discomfort ( P = 0.001 ) . This trial did not support any preference in the use of the Goshgarian or Nance palatal arch , unless the slightly reduced patient discomfort with the Goshgarian arch is considered significant INTRODUCTION The objective of this pilot r and omized clinical trial was to investigate the relative effectiveness of anchorage conservation of en-masse and 2-step retraction techniques during maximum anchorage treatment in patients with Angle Class I and Class II malocclusions . METHODS Sixty-four growing subjects ( 25 boys , 39 girls ; 10.2 - 15.9 years old ) who required maximum anchorage were r and omized to 2 treatment techniques : en-masse retraction ( n = 32 ) and 2-step retraction ( n = 32 ) ; the groups were stratified by sex and starting age . Each patient was treated by a full-time clinic instructor experienced in the use of both retraction techniques at the orthodontic clinic of Peking University School of Stomatology in China . All patients used headgear , and most had transpalatal appliances . Lateral cephalograms taken before treatment and at the end of treatment were used to evaluate treatment-associated changes . Differences in maxillary molar mesial displacement and maxillary incisor retraction were measured with the before and after treatment tracings superimposed on the anatomic best fit of the palatal structures . Differences in mesial displacement of the maxillary first molar were compared between the 2 treatment techniques , between sexes , and between different starting-age groups . RESULTS Average mesial displacement of the maxillary first molar was slightly less in the en-masse group than in the 2-step group ( mean , -0.36 mm ; 95 % CI , -1.42 to 0.71 mm ) . The average mesial displacement of the maxillary first molar for both treatment groups pooled ( n = 63 , because 1 patient was lost to follow-up ) was 4.3 ± 2.1 mm ( mean ± st and ard deviation ) . Boys had significantly more mesial displacement than girls ( mean difference , 1.3 mm ; P < 0.03 ) . Younger adolescents had significantly more mesial displacement than older adolescents ( mean difference , 1.3 mm ; P < 0.02 ) . CONCLUSIONS Average mesial displacement of the maxillary first molar  with 2-step retraction was slightly greater than that for en-masse retraction , but the difference did not reach statistical significance . This finding appears to contradict the belief of many clinicians that 2-step canine retraction is more effective than en-masse retraction in preventing clinical ly meaningful anchorage loss Background and Objective : When treating pronounced dentoalveolar compensation of a skeletal Class III malocclusion , preoperative decompensation frequently requires the extraction of maxillary lateral teeth and retraction of the incisors . In this context , maximum anchorage of the maxillary molars is frequently necessary to attain the significant increase in negative overjet that is desired . The aim of this study was to compare the quality of conventional and skeletal molar anchorage using mini-implants in association with pre-operative decompensation . Patients and Methods : Pre-operative decompensation involved the symmetric extraction of two lateral teeth from the maxilla as well as retraction of the front teeth in each of 20 patients with a marked skeletal Class III . The molar anchorage half of the patients received was conventional ( transpalatal arch ) while the other half were treated with skeletal anchorage via mini-implants inserted in the anterior palate . Study models were prepared and analyzed using a 3D scanner before and after space closure ( OrthoProof ) . We analyzed the bilateral degree of mesial molar migration and change in the transversal dimension ( DigiModel software ) . Results : All patients demonstrated mesial migration of the upper molars as a response to the load on the anchorage unit . The 4.21 mm ( ± 1.17 mm ) anchorage loss associated with conventional anchorage was greater than that of skeletal anchorage in the anterior palate ( 2.05 mm [ ± 1.39 mm ] ) . We observed a tendency towards transversal expansion in the molar region according to the design and thickness of the transpalatal arch . Conclusions : Skeletal molar anchorage proved to be more effective than the conventional anchorage . Hence , skeletal anchorage is preferable , especially when patients are in serious need of preoperative decompensation . The anterior palate has proven to be an advantageous region for insertion in conjunction with the correct mechanics . ZusammenfassungFragestellung : Bei ausgeprägten dentoalveolären Kompensationen einer skelettalen Klasse III ist i m Rahmen der prächirurgischen Dekompensation oftmals die Extraktion von Oberkiefer-Seitenzähnen mit Retraktion der Front indiziert . Die in diesem Rahmen gewünschte signifikante Vergrößerung der negativen sagittalen Frontzahnstufe erfordert oft eine maximale Verankerung der Oberkiefermolaren . Ziel dieser Studie war der Vergleich der Qualität der konventionellen und skelettalen Molarenverankerung mittels Mini-Implantaten i m Rahmen der präoperativen Dekompensation . Patienten und Method ik : Bei 20 Patienten mit einer ausgeprägten skelettalen Klasse III wurden zur präoperativen Dekompensation symmetrisch jeweils zwei Seitenzähne i m Oberkiefer extrahiert sowie eine Frontretraktion durchgeführt . Die Molarenverankerung erfolgte bei der einen Hälfte der Patienten jeweils mittels konventioneller Verankerung ( Transpalatinalbogen ) und bei der and eren Hälfte skelettal mittels Mini-Implantaten i m anterioren Gaumen . Vor und nach dem Lückenschluss wurden Studienmodelle angefertigt und mittels eines 3D-Scanners ( Ortho-Proof ) vermessen . Sowohl das beidseitige Ausmaß der Mesialw and erung der Molaren als auch eine Veränderung in der Transversalen wurden ausgewertet ( DigiModel Software).Ergebnisse : Bei allen Patienten kam es bei Belastung der Verankerungseinheit zu einer Mesialw and erung der Oberkiefermolaren . Bei konventioneller Verankerung war der Verankerungsverlust mit 4,21 mm ( ± 1,17 mm ) größer als bei skelettaler Verankerung i m anterioren Gaumen mit 2,05 mm ( ± 1,39 mm ) . Je nach Design und Stärke des Transpalatinalbogens zeigte sich eine Tendenz zur transversalen Erweiterung i m Molarenbereich . Schlussfolgerungen : Die skelettale Molarenverankerung zeigte eine höhere Effektivität als die konventionelle Verankerung . Insbesondere bei Patienten mit einem großen Bedarf an präoperativer Dekompensation sollte daher der skelettalen Verankerung der Vorzug gegeben werden . Der anteriore Gaumen erwies sich in Kombination mit einer geeigneten Mechanik für diese Aufgabe als vorteilhafte Insertionsregion The purpose of this study was to compare the differences in cephalometric parameters after active orthodontic treatment applying mini-screw implants ( G1 ) or transpalatal arches ( G2 ) as anchorage in adult patients with bialveolar dental protrusion needing extraction of four premolars . A total of 34 Chinese patients ( 18 - 33 years ) with bialveolar dental protrusion were r and omly assigned to G1 and G2 . Sliding mechanics and en-masse retraction of anterior teeth were applied to close extraction spaces . The changes in skeletal , dental and soft tissues were analyzed in both groups on lateral cephalograms before and after active orthodontic treatment . Independent sample s and paired- sample s t-tests were utilized to analyze the morphological changes in both groups . ANB angle was decreased in G1 and remained unchanged in G2 ( P < 0.05 ) . Upper incisors were retracted more in G1 than in G2 ( P < 0.01 ) . Upper incisors and molars were intruded in G1 , but extruded in G2 ( P < 0.01 ) . Although the upper molars were found with no significant distalization ( P > 0.05 ) , there existed molars distalization in some patients . However , the maxillary molars in G2 were mesialized ( P < 0.01 ) . The intrusion of upper molars in G1 result ed in counterclockwise rotation of the m and ible and decrease of SN-MP angle ( P < 0.01 ) . Upper lip linear measurements including UL-Y and UL-E were decreased more in G1 than in G2 ( P < 0.05 ) . Mini-screw implants provide absolute anchorage in vertical and sagittal directions . Better dental , skeletal and soft tissue changes could be achieved by mini-screw implants especially in hyperdivergent patients . Skeletal anchorage should be routinely recommended in patients with bialveolar dental protrusion Tooth stability is one of the most changing parameters in age . The aim of the present study has been to clarify the therapeutic benefit of the osseointegrated palatal implant ( PI ) supported anchorage in adolescents compared with conventional dental anchorage ( DA ) in extraction cases requiring ' maximum anchorage ' in growing patients following the post pubertal growth spurt . Thirty patients ( 14.22±1.37 years ) selected with homogeneous facial skeletal characteristics were divided in two groups . In the PI group , Orthosystem ( ® ) implants were placed into the palate for anchorage and the transpalatal arch ( TPA ) was fixed to the implant and to the molar b and s. In the DA group maximal anchorage was provided by a TPA and a utility arch . Super-elastic spring was used for canine- and contraction arch for incisor retraction . An insignificant difference was observed between the groups as to the duration of the canine retraction . In the PI group , the duration of the front retraction and the total treatment time was shorter compared to the DA 
    Output:
    
Based on mostly moderate risk of bias and with some certainty level , TPA alone should not be recommended to provide maximum anchorage during retraction of anterior teeth in extraction cases