Differences in facial soft tissue deviations in Class III patients with different types of mandibular asymmetry: A cone-beam computed tomography study / 대한치과교정학회지

Objective@#This study assessed the differences in soft tissue deviations of the nose, lips, and chin between different mandibular asymmetry types in Class III patients. @*Methods@#Cone-beam computed tomography data from 90 Class III patients with moderate-to-severe facial asymmetry were investigated. The sample was divided into three groups based on the extent of mandibular rolling, yawing, and translation. Soft tissue landmarks on the nose, lips, and chin were investigated vertically, transversely, and anteroposteriorly. A paired t test was performed to compare variables between the deviated (Dv) and nondeviated (NDv) sides, and one-way analysis of variance with Tukey’s post-hoc test was performed for intergroup comparisons. Pearson’s correlation coefficient was calculated to assess the relationship between the soft and hard tissue deviations. @*Results@#The roll-dominant group showed significantly greater differences in the vertical positions of the soft tissue landmarks between the Dv and NDv than other groups (P < 0.05), whereas the yaw-dominant group exhibited larger differences in the transverse and anteroposterior directions (P < 0.05). Moreover, transverse lip cant was correlated with the menton (Me) deviation and mandibular rolling in the roll-dominant group (P < 0.001); the angulation of the nasal bridge or philtrum was correlated with the Me deviation and mandibular yawing in the yaw-dominant group (P < 0.01). @*Conclusions@#The threedimensional deviations of facial soft tissue differed based on the mandibular asymmetry types in Class III patients with similar amounts of Me deviation. A precise understanding of soft tissue deviation in each asymmetry type would help achieve satisfactory facial esthetics.

Differences in positions of cone-beam computed tomography landmarks in patients with skeletal Class III facial asymmetry according to midsagittal planes / 대한치과교정학회지

Objective@#This study aimed to clarify differences in the positions of cone-beam computed tomography (CBCT) landmarks according to different midsagittal planes (MSPs) in patients with skeletal Class III facial asymmetry. @*Methods@#Pre-treatment CBCT data from 60 patients with skeletal Class III were used.The patients were classified into symmetric (menton deviations of 4 mm) groups. Six MSPs were established based on previous studies, and three-dimensional analyses were performed for the planes in both the groups. The measurement outcomes were compared statistically. @*Results@#A statistically significant interaction (p < 0.01) was observed between MSPs and facial asymmetry. No significant differences were observed among MSPs in the symmetric group. However, significant differences in linear measurements were identified among MSPs in the asymmetric group. Specifically, the upper facial MSP revealed both maxillary and mandibular transverse asymmetries. On the other hand, anterior nasal spine (ANS)-associated MSP could not identify maxillary asymmetry. Furthermore, the menton deviation was approximately 3 mm lower when estimated using the ANS-associated MSP than that using upper facial MSP. @*Conclusions@#The choice of MSP can significantly affect treatment outcomes while diagnosing patients with asymmetry. Therefore, care should be taken when selecting MSP in clinical practice.

Influence of late removal after treatment on the removal torque of microimplants / 대한치과교정학회지

Objective@#To compare the removal torque of microimplants upon post-use removal and post-retention removal and to assess the influencing factors. @*Methods@#The sample group included 241 patients (age, 30.25 ± 12.2 years) with 568 microimplants. They were divided into the post-use (microimplants removed immediately after use or treatment) and post-retention (microimplants removed during the retention period) removal groups. The removal torque in both groups was assessed according to sex, age, placement site and method, and microimplant size. Pearson correlation and multiple linear regression analyses were performed for evaluating variables influencing the removal torque. @*Results@#The mean period of total in-bone stay of microimplants in the postretention removal group (1,237 days) was approximately two times longer than that in the post-use removal group (656.28 days). The removal torques in the post-retention removal group (range, 4–5 N cm) were also higher than those in the post-use removal group. The mandible and pre-drilling groups demonstrated higher placement and removal torques than did the maxilla and no-drilling groups, respectively. In the no-drilling post-use removal group, the placement torque and microimplant length positively correlated with the removal torque. In the post-retention removal group, unloading in-bone stay period and microimplant diameter positively correlated with the removal torque in the no-drilling and pre-drilling methods, respectively. @*Conclusions@#The removal torques differed according to the orthodontic loading and removal time of microimplants. With prolonged retention of microimplants inserted using the no-drilling method, the removal torque was clinically acceptable and positively correlated with the unloading in-bone stay period.

Estimation of the prevalence of malocclusion on the basis of nationwide oral health examinations of pre-adolescent and adolescent students during 2012–2017 / 대한치과교정학회지

Objective@#To investigate the prevalence of malocclusion with respect to grade, sex, and year among Korean pre-adolescent and adolescent students during 2012–2017. @*Methods@#A total of 165,996 students (first grade [E1, 6–7 years of age], fourth grade [E4, 9–10 years], seventh grade [M1, 12–13 years], and tenth grade [H1, 15–16 years]) were selected by stratified sampling method and underwent the nationwide oral health examination performed by the Ministry of Education, Republic of Korea. The malocclusion assessments based on dentists’ judgments were “no malocclusion,” “needs orthodontic treatment (N-OTx),” and “under orthodontic treatment (U-OTx).” The sum of N-OTx and U-OTx cases was determined as the number of students with malocclusion. After analyzing the prevalence of malocclusion according to grade, sex, and year-by-year differences, Pearson correlation analyses and two-way analyses of variance were performed. @*Results@#The prevalence of malocclusion was 18.7%, which increased with the grades (E1 [8.3%] 0.05) without significant correlation (E1, ρ = 0.129; E4, ρ = –0.495; M1, ρ = 0.406; H1, ρ = –0.383; all p > 0.05). The prevalence of malocclusion within each grade group over the six-year period was more prominent in the female (p < 0.0001). @*Conclusions@#Further studies are necessary to modify the malocclusion assessment method to account for specific types of malocclusion in pre-adolescent and adolescent students.

Surface characteristics and mechanical behavior of retrieved orthodontic microimplants / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

OBJECTIVES@#To observe the surface characteristics and mechanical behavior of retrieved microimplants under clinically simulating experimental conditions and to investigate the feasibility of reuse of microimplants.@*MATERIALS AND METHODS@#The microimplants, inserted at different angles, were retrieved from the patients (RMIP) and the artificial bone (RMIA). Surface characteristics, including morphologic changes of tips and thread edges, length reduction, and surface compositional variation, were evaluated using a field emission scanning electron microscope, a stereoscopic microscope, and energy-dispersive X-ray spectroscopy, respectively. Mechanical behavior comprising maximum insertion torque (MIT) and insertion time was tested with the artificial bone under clinically simulating conditions.@*RESULTS@#The tips and thread edges were worn out to various degrees in retrieved microimplants and thin deposits were observed on the surface in the RMIP group. Traces of foreign elements, such as iron, sulphur, and calcium, were detected on the surface of RMIP. Both MIT and insertion time of retrieved microimplants were increased compared to their initial use, and were much greater in RMIP. The increases of MIT were seen in all groups inserted at the insertion angle of 45° compared with 90°, although the differences were not statistically significant.@*CONCLUSIONS@#Retrieved microimplants exhibited different degrees of changes on surface characteristics and mechanical behavior, with more changes in RMIP. The reuse of microimplants for immediate relocation in the same patient may be acceptable; however, postponed relocation and allogeneic reuse of microimplants are not recommended in clinical practice.

Subclinical Central Lymph Node Metastasis in Papillary Thyroid Microcarcinoma Evaluated as cT1aN0 by Preoperative Imaging Study / 대한갑상선학회지

BACKGROUND AND OBJECTIVES: Papillary thyroid microcarcinoma (PTMC) generally has a highly favorable prognosis, however reports show a 30-65% prevalence of subclinical central lymph node metastasis. Therefore, the role of elective central neck dissection in PTMC treatment remains controversial. Our study focused on preoperative features of clinically lymph node negative and intracapsular (cT1aN0) PTMC and the correlation of these features with subclinical central lymph node metastasis. MATERIALS AND METHODS: Of 584 PTC patients who underwent thyroidectomy at the Kosin University Gospel Hospital from January 2009 to July 2011, 219 patients with cT1aN0 PTMC were reviewed retrospectively. Pathologic results were reviewed and various clinicopathologic prognostic factors were investigated. RESULTS: Postoperative pathology report revealed capsular invasion of primary tumor in 77 patients (35.2%) and subclinical central lymph node metastasis in 62 patients (28.3%). Tumor of the isthmic location was an independent predictor of subclinical central lymph node metastasis by multivariate analysis while multifocality showed borderline significance. The presence of extrathyroidal extension (ETE), multifocality, and cervical lymph node metastasis were significantly related to PTMC of isthmus. Seven of the 14 subjects with PTMC of the isthmus (50%) had pretracheal lymph node metastasis showing significant correlation (p=0.001). CONCLUSION: Despite the absence of ETE and lymph node metastasis in the preoperative imaging studies, higher risk of subclinical central lymph node metastasis should be considered in PTMC with multifocality and tumor of the isthmus.

Direct and indirect bonding of wire retainers to bovine enamel using three resin systems: shear bond strength comparisons / 대한치과교정학회지

OBJECTIVE: We compared the shear bond strength (SBS) of lingual retainers bonded to bovine enamel with three different resins using direct and indirect methods. METHODS: Both ends of pre-fabricated twisted ligature wires were bonded to bovine enamel surfaces using Light-Core, Tetric N-Flow, or Transbond XT. Phosphoric acid-etched enamel surfaces were primed with One-Step prior to bonding with Light-Core or Tetric N-Flow. Transbond XT primer was used prior to bonding with Transbond XT. After 24 hours in water at 37degrees C, we performed SBS tests on the samples. We also assigned adhesive remnant index (ARI) scores after debonding and predicted the clinical performance of materials and bonding techniques from Weibull analyses. RESULTS: Direct bonding produced significantly higher SBS values than indirect bonding for all materials. The SBS for Light-Core was significantly higher than that for Tetric N-Flow, and there was no significant difference between the direct bonding SBS of Transbond XT and that of Light-Core. Weibull analysis indicated Light-Core performed better than other indirectly bonded resins. CONCLUSIONS: When the SBS of a wire retainer is of primary concern, direct bonding methods are superior to indirect bonding methods. Light-Core may perform better than Transbond XT or Tetric N-Flow when bonded indirectly.

Finite element analysis of peri-implant bone stresses induced by root contact of orthodontic microimplant / 대한치과교정학회지

OBJECTIVE: The aim of this study was to evaluate the biomechanical aspects of peri-implant bone upon root contact of orthodontic microimplant. METHODS: Axisymmetric finite element modeling scheme was used to analyze the compressive strength of the orthodontic microimplant (Absoanchor SH1312-7, Dentos Inc., Daegu, Korea) placed into inter-radicular bone covered by 1 mm thick cortical bone, with its apical tip contacting adjacent root surface. A stepwise analysis technique was adopted to simulate the response of peri-implant bone. Areas of the bone that were subject to higher stresses than the maximum compressive strength (in case of cancellous bone) or threshold stress of 54.8MPa, which was assumed to impair the physiological remodeling of cortical bone, were removed from the FE mesh in a stepwise manner. For comparison, a control model was analyzed which simulated normal orthodontic force of 5 N at the head of the microimplant. RESULTS: Stresses in cancellous bone were high enough to cause mechanical failure across its entire thickness. Stresses in cortical bone were more likely to cause resorptive bone remodeling than mechanical failure. The overloaded zone, initially located at the lower part of cortical plate, proliferated upward in a positive feedback mode, unaffected by stress redistribution, until the whole thickness was engaged. CONCLUSIONS: Stresses induced around a microimplant by root contact may lead to a irreversible loss of microimplant stability.

Optimization of orthodontic microimplant thread design / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to optimize the thread pattern of orthodontic microimplants. METHODS: In search of an optimal thread for orthodontic microimplants, an objective function stability quotient (SQ) was built and solved which will help increase the stability and torsional strength of microimplants while reducing the bone damage during insertion. Selecting the AbsoAnchor SH1312-7 microimplant (Dentos Inc., Daegu, Korea) as a control, and using the thread height (h) and pitch (p) as design parameters, new thread designs with optimal combination of h and p combination were developed. Design soundness of the new threads were examined through insertion strain analyses using 3D finite element simulation, torque test, and clinical test. RESULTS: Solving the function SQ, four new models with optimized thread designs were developed (h200p6, h225p7, h250p8, and h275p8). Finite element analysis has shown that these new designs may cause less bone damage during insertion. The torsional strength of two models h200p6 and h225p7 were significantly higher than the control. On the other hand, clinical test of models h200p6 and h250p8 had similar success rates when compared to the control. CONCLUSIONS: Overall, the new thread designs exhibited better performance than the control which indicated that the optimization methodology may be a useful tool when designing orthodontic microimplant threads.

A Case of Surgical Treatment for Sialolithiasis in Stensen's Duct Using Ultrasonography / 대한이비인후과학회지

In this report, we introduce a case of surgical treatment for Stensen's duct stone with ultrasonography. A 49-year-old female patient presented with postprandial swelling in the right infraauricular lesion. Upon confirming the swelling as the Stensen's duct stone on the computed tomography scan, the sialolith was surgically removed using the transcutaneous procedure. Using ultrasonography, we found the exact location of the stone and removed it without any facial nerve injury. The case clearly demonstrated that the Stensen's duct stone canbe removed more easily and safely with ultrasonography.

Qualitative and quantitative evaluation of root injury risk potentially burdening insertion of miniscrew implants / 대한치과교정학회지

OBJECTIVE: Microscrew implants (MSIs) offer many advantages, but some complications are known to occur during their insertion. One of the most commonly reported complications is root injury. Our aim was to identify factors associated with root injury and to evaluate their qualitative and quantitative values. METHODS: Thirty-five orthodontists placed MSIs (AbsoAnchor(R), Dentos Co. Ltd, Daegu, Korea) in the upper jaw of typodonts, labially between the second premolar and the first molar, in low and high vertical positions. Root contacts were counted, and distances between MSI apices and roots were measured. Fear level of the orthodontists was surveyed before and after the experiment. Wilcoxon's test, chi-square test, and Mann-Whitney test were used for statistical analysis. RESULTS: Overall root contact rate of MSI insertion was 23.57%. The root contact rate was significantly higher in MSIs inserted at 90degrees (45.71%) than at 30degrees (1.43%). The distance between the dental root and MSI also increased significantly in MSIs inserted at 30degrees. Mean fear level before MSI insertion (4.6) significantly decreased after insertion (3.2); the causative factors were risk of injury to dental root and maxillary sinus or mandibular canal. CONCLUSIONS: Root injury is relatively rare, and oblique angulation reduces the risk of root and MSI contact.

Hearing Results after Tympanoplasty Type I with Cartilage-Perichondrium Composite Island Graft / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Many materials such as fascia, perichondrium and cartilage are used for reconstruction of the tympanic membrane in middle ear surgery. Because of its stiffness, cartilage is resistant to resorption and retraction. However, cartilage grafts result in increased acoustic impedance, so its use has caused controversies as to the acoustic transfer aspect. The aim of this study is to assess hearing results after cartilage tympanoplasty and after fascia tympanoplasty. SUBJECTS AND METHOD: This study included 74 patients who had received tympanoplasty type I between 2007 and 2009, of whom 44 received cartilage and 30 fascia. The middle ear risk index was used to statistically compare the preoperative state of the two groups. Preoperative and six months- postoperative air-bone gaps at the frequency 0.5, 1, 2 and 3 kHz were assessed. RESULTS: Both groups were statistically similar with respect to the severity of middle ear pathology and the preoperative hearing levels. Overall postoperative hearing results showed air-bone gaps (ABG) < or =20 dB in 73% for the fascia group and 71% for the cartilage group. The mean postoperative gains in ABG were 8.97 dB for the fascia group and 10.84 dB for the cartilage group. There were no statistically significant differences in the postoperative frequency specific gains in ABG between the two groups. CONCLUSION: These results demonstrate that hearing results after cartilage tympanoplasty are comparable to those after fascia tympanoplasty. Although cartilage is the ideal grafting material in problem cases, a more liberal application might be suggested in such cases as in tympanoplasty type I without fear of impairing hearing.

Evaluation of potency of panoramic radiography for estimating the position of maxillary impacted canines using 3D CT / 대한치과교정학회지

OBJECTIVE: The aim of this study was to evaluate the potency of panoramic radiography for the detection of maxillary impacted canines. METHODS: Twenty-five patients were selected, comprised of 7 males (mean age: 10.9 years, range: 8.5 - 14.5 years) and 18 females (mean age: 10.9 years, range: 8.2 - 15.7 years). In total, thirty-five maxillary impacted canines were estimated. The position of the canine and root resorption of adjacent teeth were evaluated on panoramic radiography and 3D CT. RESULTS: Except for angulation to the occlusal plane, the other parameters, such as tooth length, crown width, vertical distance and lateral shift showed larger values on panoramic radiography compared to 3D CT. In palatally impacted cases, the angulation of canine was smaller, and the vertical distance to the occlusal place was larger on panoramic radiography than 3D CT. For labially impacted canines, tooth length, crown width, and angulation to the occlusal plane were similar for the two methods. The sensitivity for detecting root resorption on panoramic radiography was calculated as being 33.3% of 3D CT. CONCLUSIONS: The position of labially impacted canines can be effectively estimated using panoramic radiography, but palatally impacted canines need further investigation such as 3D CT for proper diagnosis.

Cephalometric differences in obstructive sleep apnea between obese and non-obese Korean male patients / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to compare the cephalometric measurements of obese and non-obese Korean male patients with obstructive sleep apnea syndrome (OSA). METHODS: Eighty-seven adults who had visited the Sleep Disorder Clinic Center in Keimyung University, Daegu, Korea were examined and evaluated with polysomnography (PSG) and lateral cephalogram. They were divided into 4 groups (non-obese simple snorers, obese simple snorers, non-obese OSA patients, obese OSA patients) according to AHI (Apnea-Hypopnea Index) and BMI (Body Mass Index). RESULTS: The obese OSA group had the highest AHI among the 4 groups. The non-obese OSA group had a significantly steeper mandibular angle and shorter tongue length than the obese OSA group. The hyoid bone of the obese OSA group was positioned anterior and inferior as compared with the non-obese OSA group. Multiple regression analysis showed that tongue length in the obese OSA group and retroposition of hyoid bone in the non-obese OSA group were significant determinants for the severity of AHI. CONCLUSIONS: From a cephalometric point of view, the obese and non-obese pateints with OSA may be characterized by different pathogeneses. Therefore, they have to be managed by individualized treatment. For the obese OSA patients, weight control must be advised as a first choice and for the non-obese OSA patients, oral appliance, nasal CPAP, UPPP and others could be chosen according to the obstructive sites.

Histologic and biomechanical characteristics of orthodontic self-drilling and self-tapping microscrew implants / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to compare the histological and biomechanical characteristics of self-tapping and self-drilling microscrew implants. METHODS: 112 microscrew implants (56 self-drilling and 56 self-tapping) were placed into the tibia of 28 rabbits. The implants were loaded immediately with no force, light (100 gm), or heavy force (200 gm) with nickel-titanium coil springs. The animals were sacrificed at 3- and 5-weeks after placement and histologic and histomorphometric analysis were performed under a microscope. RESULTS: All microscrew implants stayed firm throughout the experiment. There was no significant difference between self-drilling and self-tapping microscrew implants both in peak insertion and removal torques. Histologic examinations showed there were more defects in the self-tapping than the self-drilling microscrew implants, and newly formed immature bone was increased at the interface in the self-tapping 5-week group. There was proliferation of bone towards the outer surface of the implant and/or toward the marrow space in the self-drilling group. Histologically, self-drilling microscrew implants provided more bone contact initially but the two methods became similar at 5 weeks. CONCLUSION: These results indicate the two methods can be used for microscrew implant placement, but when using self-tapping microscrew implants, it seems better to use light force in the early stages.

Comparison of histologic observation and insertional and removal torque values between titanium grade 2 and 4 microimplants / 대한치과교정학회지

The purpose of this study was to evaluate the light microscopic features and the maximum insertional and removal torque value of microimplants, made from titanium grade 2 or 4, in the tibia of 6 rabbits. First, the maximum torque values of microimplants at implantation were measured. After 2, 8, and 12 weeks of healing time, the microimplant-containing segments of tibia of 2 rabbits were removed and the maximum removal torque of each microimplant were measured. Comparisons of histologic examination and insertional and removal torque values were carried out for the two groups of microimplants. Removal torque values were significantly increased in both groups after 8 and 12 weeks as compared to 2 weeks after implantation. Other values measured did not show any statistically significant differences and there were no histological differences between grade 2 and 4 titanium. Based on these results, this study showed that there were no significant differences between grade 2 and 4 titanium. It seems better to use grade 4 titanium for making microimplants because grade 4 titanium is mechanically harder than grade 2 titanium and has similar retention.

The treatment of an impacted canine related with a miniplate inserted for mandibular fracture / 대한치과교정학회지

This case report describes the treatment of an impacted tooth in relation to pediatric mandibular fracture. A 10-year-old girl presented with an impacted mandibular canine related with a miniplate in the left mandibular body area. An ordinary surgical traction ended in failure. Good occlusion was established by removal of the miniplate. It would be considered important to make an exact diagnosis of the cause and remove the mechanical obstruction instantly for successful orthodontic treatment of an impacted tooth.

Clinical study on success rate of microscrew implants for orthodontic anchorage / 대한치과교정학회지

To provide some guideline for microscrew implants, 73 patients that received a total of 180 mini- or microscrew implants were scrutinized. The overall success rate was 93.3% (168 among 180 mini- or microscrew implants) and the mean period of utilization was 15.8 months. Microscrew implants in the UB group (maxillary buccal area) succeeded at a rate of 94.6% (87 among 92), mini- or microscrew implants in the LB group (mandibular buccal area) succeeded 96.6% of the time (56 out of 58), while microscrew implants in the UP group (maxillary palatal area) had a 100% success rate (11 out of 11), and mini- or microscrew implants in the LR group (retromolar area) succeeded in 73.7% of cases (14 among 19). This study might indicate that microscrew implants can be used successfully as orthodontic anchorage in daily orthodontic practice.

An anatomical study using CT images for the implantation of micro-implants / 대한치과교정학회지

Surgical microscrews were introduced and used as one method to provide absolute anchorage. Some clinicians implanted microscrews or miniscrews into the basal bone below the roots of the teeth to evade damage to the roots. Because the implanted microscrews were positioned too low the applied force was insufficient to retract the anterior teeth or protract the posterior teeth, and the use of microscrews or miniscrews seemed limited in applying vertical force. However Park implanted microscrews(micro-implants (1.2 mm in diameter)) into the alveolar bone between the roots of the posterior teeth to change the direction of the applied force toward increasing horizontal component of the force. Moreover, these microscrew implants were positioned in the alveolar bone between the roots without causing discernable damage to the roots. This study was performed to provide guidelines and anatomic data to assist in the determination of the safe location for micro-implants. By measuring the CT images from 21 patients, anatomical data were obtained which were then used as a guide to determine the location for the implantation of micro-implants. The thickness of the cortical bones at the alveaolar bone region increased from the anterior to the posterior teeth area. The mandibular posterior teeth area showed thicker cortical bone. A greater distance was observed in distance between the second premolar root and first molar root in the upper arch, between the first molar root and the second molar root in the lower arch. The alveolar bone of the posterior teeth area is considered the best site for the implantation of micro-implants.

A new protocol of the sliding mechanics with micro-implant anchorage(M.I.A.) / 대한치과교정학회지

Anchorage plays an important role in orthodontic treatment. Because of limited anchorage potential and acceptance problems of intra- or extraoral anchorage aids, endosseous implants have been suggested and used. However, clinicians have hesitated to use endosseous implants as orthodontic anchorage because of limited implantation space, high cost, and long waiting period for osseointegration. Titanium miniscrews and microscrews were introduced as orthodontic anchorage due to their many advantages such as ease of insertion and removal, low cost, immediate loading, and their ability to be placed in any area of the alveolar bone. In this study, a skeletal Class II patient was treated with sliding mechanics using M.I.A.(micro-implant anchorage). The maxillary micro-implants provide anchorage for retraction of the upper anterior teeth. The mandibular micro-implants induced uprighting and intrusion of the lower molars. The upward and forward movement of the chin followed. This resulted in an increase of the SNB angle, and a decrease of the ANB angle. The micro-implants remained firm and stable throughout treatment. This new approach to the treatment of skeletal class II malocclusion has the following characteristics: . Independent of patient cooperation. . Shorter treatment time due to the simultaneous retraction of the six anterior teeth . Early change of facial profile motivating greater cooperation from patients These results indicate that the M.I.A. can be used as anchorage for orthodontic treatment. The use of M.I.A. with sliding mechanics in the treatment of skeletal Class II malocclusion increases the treatment simplicity and efficiency.