open bite is considered as a deviation in the vertical relationship of the maxillary and mandibular dental arches , characterized by a lack of contact between opposing segments of teeth . open bite develops because of interaction of many etiologic factors , both hereditary and environmental in nature . treatment of skeletal open bite is regarded as one of the most complicated and challenging treatments in the orthodontic specialty . control of the vertical dimension and the height of the posterior dentoalveolar regions is considered the most important factor in successfully treating patients with skeletal open bite and hyperdivergency . for the correction of anterior open bite with a steep mandible and excessive molar height , intrusion of the posterior teeth is generally the best option . however , intrusion of the molar teeth is quite difficult to obtain with traditional mechanics . in recent years , temporary anchorage devices ( tads ) have been increasingly used for skeletal open bite patients because they provide absolute molar intrusion , which used to be impossible with traditional orthodontic mechanics combined with intra- or extra - oral anchorage . moreover , with the use of tads , the vertical correction of the posterior dentoalveolar region without unfavorable side effects has become possible . the infrazygomatic crest has been used successfully to provide skeletal anchorage for the intrusion of the maxillary posterior teeth . on this subject , several case reports have already been published . however , leading research articles have lacked sufficient sample sizes , some of them have lacked matched untreated controls , and some of them were retrospective , observational studies and not randomized clinical trials . to the best of our knowledge , there have been no randomized , controlled trials evaluating the efficiency of tads in the treatment of skeletal anterior open bites . therefore , the aims of the current study were to evaluate the effects of tads in the treatment of skeletal open bites and to compare the results with untreated controls . this study was approved by the ethics committee of the faculty of medicine of suleyman demirel university . written informed consent was provided by the patients and their parents before evaluation . required sample size for 0.90 power of the study three most affected variables ( sn / gogn , n - me , and ans - me ) were selected , and minimum required sample sizes were 12 , 22 , and 24 . we decided to begin the study with forty patients , and the achieved power was 0.99 . subjects meeting the following criteria were included in the study : 
 no systemic diseaseno previous orthodontic treatmentpermanent dentition stageminimum of 2 mm of anterior open bite . 
  no previous orthodontic treatment permanent dentition stage minimum of 2 mm of anterior open bite . a total of forty patients were randomly assigned to two groups of twenty each . each case the mean chronological age for the treatment group ( 14 female , 6 male ) was 16.68  2.80 years old , compared to 16.63  2.83 years old for the control group ( 11 female , 9 male ) [ table 1 ] . the materials of this study consisted of eighty lateral cephalometric films and eighty dental casts obtained before ( t1 ) and at the end of the treatment or of the observation period ( t2 ) . the mean observation period for the treatment group was 1.00  0.31 years , compared to 0.95  0.14 years for the control group [ table 1 ] . baseline characteristics and statistical comparison of the groups a rigid hyrax appliance was used to avoid unintentional buccal tipping of the posterior teeth by the intrusive forces . the appliance was adapted at least 3 mm away from the palate [ figure 1 ] . the transpalatal arch with hyrax screws used in the study a local anesthetic was infiltrated bilaterally at the zygomatic process areas . the surgical method , as previously described by erverdi et al . , was made along the zygomatic buttress and ending at the mucogingival junction . by means of blunt dissection , three - hole titanium miniplates ( trimed , ankara , turkey ) were adjusted to fit the contour of the infrazygomatic crest , and they were fixed with 7 and 9 mm screws ( trimed , ankara , turkey ) [ figure 2 ] . the patients were advised and instructed how to brush and to rinse with 0.2% chlorhexidine . the steps of the surgical procedure orthodontic brackets with 0.018-inch slot size were bonded on the upper first and second premolar teeth and attached to the transpalatal arch ( tpa ) by 0.016  0.022-inch stainless steel partial arch wires . nickel - titanium closed coil springs were used to deliver approximately 200 g of intrusive force from the miniplates to the posterior teeth . a total of 19 landmarks were identified on each cephalogram , and the treatment and normal growth changes between t1 and t2 were evaluated by 2 angular and 20 linear measurements , for a total of 22 measurements [ table 2 ] . all of the measurements were performed with dolphin imaging system ( dolphin imaging and management solutions , chatsworth , ca , usa ) . description of the linear and angular measurements the total and local structural superimposition method of bjrk and skieller was used to assess changes during the study period . a sella - nasion line was used as a horizontal reference line ( x ) in the total structural superimposition . this perpendicular line was extended parallel 28 mm to the left , and all of the horizontal dimensional measurements were ensured to be positive values . this extended vertical line was used as a vertical reference line ( y ) [ figure 3 ] . the total superimposition measurements the ans - pns line was used to evaluate the maxillary dentoalveolar changes according to their basal structures . the ans - pns line was used as a horizontal reference line , and a perpendicular line passing through the pns was drawn to the horizontal axis , which was used as a vertical reference line [ figure 4 ] . the maxillary and mandibular local superimposition measurements the go - gn line was used as a horizontal reference line in the mandibular local superimposition . a vertical reference line was drawn from the gonion perpendicular to the horizontal reference line [ figure 4 ] . the coordinate systems constructed on the first cephalogram ( t1 ) were transferred to the second cephalogram ( t2 ) , and measurements were performed accordingly . interpremolar and intermolar widths [ table 2 ] were measured on plaster models with digital calipers to the nearest 0.01 mm . all of the statistical analyses were performed using spss software , version 15.0 for windows ( spss inc . , a rigid hyrax appliance was used to avoid unintentional buccal tipping of the posterior teeth by the intrusive forces . the appliance was adapted at least 3 mm away from the palate [ figure 1 ] . the transpalatal arch with hyrax screws used in the study a local anesthetic was infiltrated bilaterally at the zygomatic process areas . the surgical method , as previously described by erverdi et al . , was made along the zygomatic buttress and ending at the mucogingival junction . by means of blunt dissection three - hole titanium miniplates ( trimed , ankara , turkey ) were adjusted to fit the contour of the infrazygomatic crest , and they were fixed with 7 and 9 mm screws ( trimed , ankara , turkey ) [ figure 2 ] . the patients were advised and instructed how to brush and to rinse with 0.2% chlorhexidine . the steps of the surgical procedure orthodontic brackets with 0.018-inch slot size were bonded on the upper first and second premolar teeth and attached to the transpalatal arch ( tpa ) by 0.016  0.022-inch stainless steel partial arch wires . nickel - titanium closed coil springs were used to deliver approximately 200 g of intrusive force from the miniplates to the posterior teeth . a total of 19 landmarks were identified on each cephalogram , and the treatment and normal growth changes between t1 and t2 were evaluated by 2 angular and 20 linear measurements , for a total of 22 measurements [ table 2 ] . all of the measurements were performed with dolphin imaging system ( dolphin imaging and management solutions , chatsworth , ca , usa ) . description of the linear and angular measurements the total and local structural superimposition method of bjrk and skieller was used to assess changes during the study period . a sella - nasion line was used as a horizontal reference line ( x ) in the total structural superimposition . this perpendicular line was extended parallel 28 mm to the left , and all of the horizontal dimensional measurements were ensured to be positive values . this extended vertical line was used as a vertical reference line ( y ) [ figure 3 ] . the total superimposition measurements the ans - pns line was used to evaluate the maxillary dentoalveolar changes according to their basal structures . the ans - pns line was used as a horizontal reference line , and a perpendicular line passing through the pns was drawn to the horizontal axis , which was used as a vertical reference line [ figure 4 ] . the maxillary and mandibular local superimposition measurements the go - gn line was used as a horizontal reference line in the mandibular local superimposition . a vertical reference line was drawn from the gonion perpendicular to the horizontal reference line [ figure 4 ] . the coordinate systems constructed on the first cephalogram ( t1 ) were transferred to the second cephalogram ( t2 ) , and measurements were performed accordingly . interpremolar and intermolar widths [ table 2 ] were measured on plaster models with digital calipers to the nearest 0.01 mm . all of the statistical analyses were performed using spss software , version 15.0 for windows ( spss inc . , to calculate the method error of the study , twenty of the eighty lateral cephalometric films were selected randomly , and both the tracings and measurements were repeated . statistical comparisons of the groups at t1 revealed no statistically significant differences in any of the measurements ( p > 0.05 ) . these results showed that the treatment and control groups were fully matched and almost identical [ table 1 ] . the statistical intergroup comparison of the differences of the measurements ( t2-t1 ) is shown in table 3 . statistically significant differences were found between the groups in bx , by , sn / gogn , ax - bx , u6x , u6y , overjet , overbite , sn / occp , n - me , ans - me , s - go / n - me , interpremolar width , and intermolar width ( p < 0.05 ) . statistical comparison of the differences ( t2-t1 ) between the groups in the treatment group , statistically significant upper molar intrusion ( mean  standard deviation [ sd ] , 3.59  1.34 ; 95% confidence interval [ ci ] , 2.964.22 ) , posterior rotation of the occlusal plane ( mean  sd , 3.42  2.17 ; 95% ci , 2.394.43 ) , anterior rotation of the mandible ( mean  sd , 2.25  1.91 ; 95% ci , 1.363.14 ) . and resultant overbite improvement ( mean  sd , 4.82  1.53 ; 95% ci , 4.105.53 ) were found ( p < 0.05 ) . significant reductions in total anterior ( mean  sd , 2.38  2.60 ; 95% ci , 1.163.60 ) and lower anterior face heights ( mean  sd , 3.30  1.68 ; 95% ci , 2.514.09 ) were determined ( p < 0.05 ) . tads have opened up a new era in the management of severe dentofacial deformities , in which surgery had been the only option . with the successful intrusion of the maxillary molars , the mandible automatically rotates anteriorly , resulting in open - bite closure . a study by umemori et al . first demonstrated the effective intrusion of mandibular molars when titanium miniplates were used for anchorage in humans . later , erverdi et al . suggested that the zygomatic buttress area was an ideal anchorage site for maxillary molar intrusion , and they reported the successful closure of anterior open bites . in our study , the appliance and the mechanics successfully intruded the upper molars . this amount of intrusion , to a large extent , was obtained by buccal intrusive forces . however , to a lesser extent , the tpas might have contributed additional intermittent intrusive force of the tongue onto the molars . mesial movement of the molars by 1.52 mm was found in treatment group . as reported by furst et al . , infrazygomatic crest areas could be located in different mesiodistal positions in each individual . the location can cause some mesially directed forces acting on the molars , as well as mesial migration . moreover , the location of the most proximal loop of the plate could also cause unfavorable mesiodistal angulation during the intrusion . after intrusion of the molars , autorotation of the mandible has been reported by several authors . this result was also true for our study because intrusion of the maxillary molars caused a significant anterior rotation of the mandible . the mandibular plane closed by an average of 2.25 , resulting in 3 mm of upward and forward movement of the chin . this distance is the desired movement because significant mandibular posterior rotation and accompanying increases in anterior face heights are common characteristics of skeletal open bites . our results showed that a significant amount of reduction occurred in the lower anterior face height , resulting in a more balanced facial profile . the significant amount of decrease in the ax - bx measurement revealed that the maxillary - mandibular skeletal base discrepancy was also treated with molar intrusion . when molars are intruded , the mandible rotates anteriorly , and the chin prominence increases . therefore , we suggest that molar intrusion using tads could be very useful in treating class ii open bite cases with chin deficiency . in the treatment of skeletal open bite , the most important treatment goal is to obtain a positive overbite . in our study , the net gain in overbite was 4.8 mm , and this amount of correction was only attained by the intrusion of the maxillary molars . no extrusive forces were applied to the anterior teeth , which is very important because elongation of the anterior teeth provides unaesthetic results and leaves the skeletal component of the deformity unchanged . moreover when we evaluated transversal changes in maxillary arches , we noted small increases in the interpremolar and intermolar widths . the amount of expansion in the molar region was only 0.5 mm , which is clinically insignificant . ifter suggested using tpas with two rigid arches to prevent vestibule inclination of the molar teeth during intrusion . moreover , using hyrax screws provided the advantage that the orthodontist could counteract the buccal forces by reversely activating the screw if undesirable expansion occurred . a limitation of the present study was the presenting of short - term results immediately after the intrusion stage . posttreatment , postretention , and long - term follow - up are needed to determine clearly whether the results and obtained overbite were stable or not . mild to moderate skeletal anterior open bites can be easily treated with tads without orthognathic surgerywith the rigid anchorage of miniplates , true molar intrusion of up to 4 mm was achievedwith molar intrusion , anterior rotation of the mandible and significant reduction in anterior face heights were determinedrigid tpa with hyrax screws maintained the transverse dimension in the molar area . mild to moderate skeletal anterior open bites can be easily treated with tads without orthognathic surgery with the rigid anchorage of miniplates , true molar intrusion of up to 4 mm was achieved with molar intrusion , anterior rotation of the mandible and significant reduction in anterior face heights were determined rigid tpa with hyrax screws maintained the transverse dimension in the molar area .
objective : the aims of this study were to evaluate the effects of temporary anchorage devices ( tads ) in the treatment of skeletal open bites and to compare the results with untreated controls.materials and methods : a total of forty patients with skeletal anterior open bites were assigned to two groups of twenty each . 
 the mean chronological age for the treatment group ( 14 female , 6 male ) was 16.68  2.80 years old , compared with 16.63  2.83 years old for the control group ( 11 female , 9 male ) . 
 titanium miniplates fixed bilaterally to the infrazygomatic crest area were used as tads and intrusive forces were applied to the posterior teeth with ni - ti coil springs . the treatment and normal growth changes were evaluated using 24 measurements ( 2 angular , 22 linear).results : statistically significant differences were found between the groups in bx , by , sn / gogn , ax - bx , u6x , u6y , overjet , overbite , sn / occp , n - me , ans - me , s - go / n - me , interpremolar width , and intermolar width ( p < 0.05 ) . in the treatment group , 
 statistically significant upper molar intrusion ( mean  standard deviation [ sd ] , 3.59  1.34 ; 95% confidence interval [ ci ] , 2.964.22 ) , posterior rotation of the occlusal plane ( mean  sd , 3.42  2.17 ; 95% ci , 2.394.43 ) , anterior rotation of the mandible ( mean  sd , 2.25  1.91 ; 95% ci , 1.363.14 ) , and resultant overbite improvement ( mean  sd , 4.82  1.53 ; 95% ci , 4.105.53 ) were found ( p < 0.05).conclusions : mild to moderate skeletal anterior open bites could easily be treated with tads without orthognathic surgery . with the rigid anchorage of miniplates , true molar intrusion of up to 4 
 mm was achieved . with molar intrusion , anterior rotation of the mandible and a significant reduction in anterior face height were determined .