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Objectives: The purpose of this study was to use Finite Element Method (FEM) to simulate various clinical protocols for maxillary protraction with micro-implants, which can provide skeletal changes without the use of surgery. We aim to analyze how location and direction force alters the skeletal effect. Analysis of the skeletal effects can be used to improve clinical protocols for treating class III patients.Methods: A 3-dimensional cranial mesh model with associated maxillary sutures was developed from CT images and Mimics modeling software. Utilizing ANSYS simulation software, protraction forces were applied at different locations and directions to simulate conventional facemask therapy; seven different maxillary protraction protocols utilizing micro-implants. Stress distribution and displacement were analyzed. Video animations and superimpositions were created to illustrate the skeletal effect from varying location and direction of force application.Results: Conventional facemask and facemask from anterior micro-implants at 15� below and 30� above the occlusal plane result in counter-clockwise rotation of the maxillary complex. In contrast, maxillary protraction at 45� below the occlusal plane with anterior or posterior micro-implants displayed clockwise rotation of the maxilla. At 30� below the occlusal plane, Facemask with palatal or anterior micro-implants translated the maxilla downward and forward, while protraction from posterior micro-implants closely resembled pure anterior protraction of the maxilla. Facemask without micro-implants resulted in higher internal stresses, suggesting force dissipation to bone rather than to the sutures. Conclusion: Location of micro-implant placement and direction of pull altered the skeletal response, changing the upward or downward displacement of the maxillary complex, maxillary incisor upward or downward movement, and amount of protraction. Brachyfacial class III patients with a deep bite would benefit from counter-clockwise rotation of the maxilla, resulting in bite opening. Dolicofacial patients with open bite tendency require protraction that minimizes maxillary downward movement. As a result, class III growth modification treatment with micro-implants can be customized for each patient to maximize clinical effectiveness.

The purpose of this study was to investigate the nature of stress distributions in the craniofacial sutures produced by orthopaedic maxillary protraction forces applied to the upper canines. A three-dimensional finite element model of the craniofacial complex was developed for finite element analysis. An anteriorly directed force of 1·0 kg was applied to the upper canines in three different directions, i.e. parallel, 30 degrees upwards and downwards to the functional occlusal plane. Normal stresses acting on the sutural systems were greatest when force was applied in the 30 degrees upward direction. Furthermore, relatively large compressive stresses were induced in the frontonasal and frontomaxillary sutures, indicating that forward and upward rotation of the nasomaxillary complex was produced with substantial distortion of the complex, by the forces applied in both parallel and 30 degrees upward directions. A 30 degrees downward force produced almost uniform tensile stresses in the zygomaticotemporal and zygomaticomaxillary sutures, with least compressive stresses in the frontonasal and frontomaxillary sutures located in the superior region of the complex. This would indicate a uniform stretch of the nasomaxillary complex in both anterior and inferior directions, With negligible distortion of the complex and would be appropriate for accelerating natural growth of the nasomaxillary complex.

Over the last 15 years, cleft lip and palate (CLP) patients with maxillary deficiency in the care of the Bergen CLP Team have received interceptive orthopedic treatment to correct anterior and posterior crossbites during the deciduous and mixed dentition periods. The present study comprises 72 subjects of various cleft types with anterior crossbite, treated to an acceptable positive overjet by maxillary protraction using a facial mask (Delaire). Lateral cephalograms were taken immediately before and after the active treatment periods. Individuals exhibiting a favorable (fair) skeletal response to the protraction were compared with those who revealed little, (poor) skeletal response. Two cephalometric variables were chosen for the evaluation of the sagittal skeletal treatment changes: (1) the sagittal maxillomandibular change (change of angle ss-n-sm [ANB]); and (2) the forward movement of the maxilla (change of distance NSP-maxp), where maxp (maxillary point) represents the anterior contour of maxilla and NSP is the perpendicular to the naslon-sella-line (NSL) through sella. A numerical change greater than or equal to the value 1.5 (degrees or mm, respectively) was classified as fair versus poor response revealing a change less than 1.5. Fair-response (favorable response) of sagittal maxillomandibular change was found in 63 % of the cases (mean increase of angle ANB was 3.3 degrees), more often when protraction started early. The length of maxilla was increased, the skeletal maxilla was moved forward 1.8 mm, the upper dentition advanced 3.6 mm, the occlusal line was clockwise rotated, and the anterior face height was increased. Similarly, fair-response of forward movement of maxilla was found in 44% of the cases (mean increase of distance NSP-maxp was 2.4 mm), more often when protraction was started early and after long treatment duration. The maxillary prognathism increased 1.8 degrees, the angle ANB increased 3 degrees, the length of maxilla increased 1.5 mm, and the upper dentition was advanced 3.7 mm. The anterior face height increased with counterclockwise rotation of the nasal line, whereas the occlusal line was clockwise rotated. A paired fair-response of both skeletal maxillomandibular change and skeletal forward movement of maxilla was found in 35% of the cases. During protraction the mean increase of maxillary prognathism was 2.1 degrees, the maxilla moved forward 3.1 mm, the maxillary dentition advanced 4.3 mm, the maxillary length increased 1.9 mm, the ANB angle increased 3.7 degrees, and the lower anterior facial height increased 3.4 mm.

Introduction: Treatment with Rapid Maxillary Expansion (RME) and Facemask Therapy (FM) has been reported as one of the most effective forms of treatment for patients with Class III malocclusion, with maxillary involvement. Objective: To evaluate the cephalometric changes in the facial tegumentary in patients with malocclusion of skeletal Class III with maxillary retrusion, with greater or less extent, immediately after orthopaedic therapy, with RME/FM. Methods: The treatments with RME/FM were performed by a single operator in a suitably selected sample (10 girls and 6 boys), whose the initial and final data were collected on two times (T0 and T1), evaluating cephalometric parameters and soft tissue. The experimental phase lasted about 12 months. The data were analyzed and compared statistically (Wilcoxon Test - SPSS 13.0), through descriptive analysis, on changes in facial tissue and bone, and dental conditions. Results: A significant increase in maxillary forward growth, inhibition of mandibular forward growth, and clockwise rotation of the mandible were observed. The maxillary incisors were significantly proclined and the mandibular incisors significantly retroclined. Conclusion: Changes produced in the midface were clinically and cephalometric observed, demonstrating anterior displacement of maxilla and point "A", improvement in facial convexity, correction of the anterior crossbite, increase in the overbite and overjet. However, more studies are needed, since the information in the literature are still inconclusive, given the divergent findings and consensus between authors. Introdução: O tratamento Ortodôntico com Expansão Rápida da Maxila (ERM) e Tração Reversa (TR) tem sido descrito na literatura como uma das mais eficazes formas de tratamento, para pacientes portadores de má oclusão de Classe III, com envolvimento maxilar. Objetivo: Avaliar as alterações cefalométricas e no tegumento da facial, em pacientes portadores de má oclusão de Classe III esquelética, com retrusão maxilar em maior ou menor grau, imediatamente após o tratamento com ERM/TR. Metodologia: Os tratamentos com ERM/TR foram realizados pelo pesquisador, em uma amostra convenientemente selecionada, sem distinção de gênero (10 meninas e 6 meninos), jovens, com necessidade de tratamento, onde os dados iniciais e finais foram coletados em dois momentos (T0 e T1), avaliando parâmetros cefalométricos ósseos e de tecidos moles. O período experimental foi de aproximadamente 12 meses. Os resultados foram analisados e comparados estatisticamente (Teste de Wilcoxon - SPSS 13.0), por meio de análises descritivas, quanto às alterações ósseas e no tegumento facial, e quanto às modificações dentárias. Resultados: Significante aumento no crescimento anterior da maxila, limitação do crescimento anterior da mandíbula, rotação mandibular no sentido horário. Incisivos maxilares foram significativamente proclinados e incisivos mandibulares retroinclinados. Conclusão: As alterações produzidas na face média foram clinica e cefalometricamente observadas, demonstrando anteriorização da maxila e do ponto A , melhora na convexidade facial, correção do cruzamento anterior, viabilização de sobremordida e sobressaliência positivas. Entretanto, mais estudos são necessários, visto que as informações existentes na literatura ainda são pouco conclusivas, dadas as divergências de achados e de consenso entre autores.

Contains fulltext : 96373.pdf (Publisher’s version ) (Open Access) OBJECTIVE: To evaluate the success rate of Bollard miniplate anchorage for bone anchored maxillary protraction (BAMP). MATERIALS AND METHODS: Twenty-five consecutive patients (mean age, 12.0 +/- 1.2 years; range, 8.7-14.8 years) with maxillary hypoplasia without congenital or acquired deformation were included in this study. A total of 100 Bollard modified miniplates were placed by the same surgeon. Ninety-nine miniplates were inserted under general anesthesia, and one was placed under local anesthesia because of initially soft bone conditions. Loading of the miniplates with 150 g elastics was initiated at 17.5 +/- 6.9 days (range, 11-38 days) after surgery. Mean follow-up was provided at 20.8 +/- 11.1 months (range, 6.5-46.2 months). RESULTS: The overall success rate of miniplate anchorage in terms of stability was 97%. During orthodontic loading, five miniplates showed signs of mobility. After interruption of loading over 2 months, two miniplates became stable again. However, a total of three miniplates needed to be removed and were successfully replaced under local anesthesia after a mean healing period of 3 months. CONCLUSION: Skeletal anchorage by means of Bollard modified miniplates is effective for BAMP. Success depends on proper presurgical patient counseling, minimal invasive surgery, good postsurgical instructions, and orthodontic follow-up. 01 november 2011

A simple yet innovative attaching the J-hook along with an rapid maxillary appliance for the protraction of maxilla is presented. The proposed method not only simplifies construction but also is equally effective.

To test the hypothesis that there is no difference in the active treatment effects for maxillary advancement induced by bone-anchored maxillary protraction (BAMP) and the active treatment effects for face mask in association with rapid maxillary expansion (RME/FM).This is a study on consecutively treated patients. The changes in dentoskeletal cephalometric variables from start of treatment (T1) to end of active treatment (T2) with an average T1-T2 interval of about 1 year were contrasted in a BAMP sample of 21 subjects with a RME/FM sample of 34 patients. All subjects were prepubertal at T1. Statistical comparison was performed with t-tests for independent samples.The BAMP protocol produced significantly larger maxillary advancement than the RME/FM therapy (with a difference of 2 mm to 3 mm). Mandibular sagittal changes were similar, while vertical changes were better controlled with BAMP. The sagittal intermaxillary relationships improved 2.5 mm more in the BAMP patients. Additional favorable outcomes of BAMP treatment were the lack of clockwise rotation of the mandible as well as a lack of retroclination of the lower incisors.The hypothesis is rejected. The BAMP protocol produced significantly larger maxillary advancement than the RME/FM therapy.

The aim of this study was to evaluate and compare the dentofacial effects of 1 week rapid palatal expansion (RPE) and activation-deactivation (A/D) RPE protocols with reverse headgear (RH). Two groups, each containing 15 subjects, were included in this study. In the RPE group (seven males and eight females, 11.94 ± 1.62 years), Hyrax screws were activated every 12 hours for 1 week. At the end of this period, RPE was stopped and the patients were instructed to wear the RH. In the A/D-RPE group (seven males and eight females, 11.34 ± 1.81 years), the screws were activated every 12 hours for 1 week. Subsequently, the screws were deactivated every 12 hours for 1 week followed by activation and deactivation for the following 2 weeks. After this protocol, the patients were instructed to use the RH. A total force of 700 g was applied to both groups for 16-18 hours/day for the first 3 months, for 12 hours/day for the second 3 months, and for 6 hours/day for the second 6 months. Lateral cephalometric films were taken before treatment (T1) and at the end of the first (T2) and second (T3) 6 months to evaluate the dentofacial changes. Intragroup differences of each landmark at T2-T1, T3-T2, and T3-T1 were analysed with a paired t-test (P < 0.016), and intergroup differences were compared with an independent t-test (P < 0.05). Anterior movement of point A (4.13 mm) for the A/D-RPE group was approximately twice of the RPE group (2.33 mm; P < 0.001). Backward movement of the mandible showed no significant difference between the groups. Anterior face height increases did not demonstrate significant differences between the groups. The pronounced anterior movement of point A demonstrates that the A/D-RPE procedure positively affects maxillary protraction.

To test the hypothesis that there is no difference between the effects of maxillary protraction on anterior crossbites in repaired unilateral cleft lip and palate (UCLP) and noncleft prepubertal boys.Eighteen operated UCLP boys with anterior crossbite (aged 9.54 +/- 1.21 years) were the experimental subjects. Eighteen noncleft boys with similar malocclusion (aged 9.75 +/- 1.46 years) were selected as a control group. A Hyrax appliance and reverse headgear were applied. Lateral cephalometric radiographs were taken before and after the treatment. Computerized cephalometric analysis and statistics were carried out.There were no significant differences in anterior movement of point A between the two groups (P.05). ANB increased by 3.82 degrees and A-Pg (FH) increased by 5.89 mm in the UCLP group. ANB increased by 2.68 degrees and A-Pg (FH) increased by 3.66 mm in the noncleft group. The change of sagittal skeletal intermaxillary relationships was significantly larger in the UCLP group than in the noncleft group (P.05). The change of lower lip in the UCLP group was less than in the noncleft group (P.05). : The hypothesis is rejected. The changes of sagittal skeletal intermaxillary relationship and mandibular clockwise rotation were larger in the operated UCLP patients than in the noncleft subjects. The amount of the lower lip retrusion was significantly less in the UCLP patients.

Introduction The purpose of this finite element study was to evaluate biomechanically 2 treatment modalities—maxillary protraction alone and in combination with maxillary expansion—by comparing the displacement of various craniofacial structures. Methods Two 3-dimensional analytical models were developed from sequential computed tomography scan images taken at 2.5-mm intervals of a dry young skull. AutoCAD software (2004 version, Autodesk, San Rafael, Calif) and ANSYS software (version 10, Belcan Engineering Group, Cincinnati, Ohio) were used. The model consisted of 108,799 solid 10 node 92 elements, 193,633 nodes, and 580,899 degrees of freedom. In the first model, maxillary protraction forces were simulated by applying 1 kg of anterior force 30° downward to the palatal plane. In the second model, a 4-mm midpalatal suture opening and maxillary protraction were simulated. Results Forward displacement of the nasomaxillary complex with upward and forward rotation was observed with maxillary protraction alone. No rotational tendency was noted when protraction was carried out with 4 mm of transverse expansion. A tendency for anterior maxillary constriction after maxillary protraction was evident. The amounts of displacement in the frontal, vertical, and lateral directions with midpalatal suture opening were greater compared with no opening of the midpalatal suture. The forward and downward displacements of the nasomaxillary complex with maxillary protraction and maxillary expansion more closely approximated the natural growth direction of the maxilla. Conclusions Displacements of craniofacial structures were more favorable for the treatment of skeletal Class III maxillary retrognathia when maxillary protraction was used with maxillary expansion. Hence, biomechanically, maxillary protraction combined with maxillary expansion appears to be a superior treatment modality for the treatment of maxillary retrognathia than maxillary protraction alone.

Maxillary protraction is recommended for patients with skeletal Class III malocclusion diagnosed with maxillary deficiency. The major goal of the protraction is to correct maxillary discrepancy with a skeletal alteration rather than dental movements. However, loss of the dental anchorage has been reported beside the skeletal effects with facemask therapy using tooth-borne anchorage. The use of miniscrews and miniplates became popular as an anchorage instead of conventional tooth-borne appliances. Studies evaluating the second-phase treatment results and stability of bone-anchored maxillary protraction are needed in literature. This case report presents the treatment of 11 and 12-year-old two boys with Class III malocclusion due to maxillary deficiency. Both cases were treated with fixed appliances subsequent to maxillary protraction with miniplates. Maxillary skeletal effects were increased, and undesired dentoalveolar effects were reduced by the facemask therapy with skeletal anchorage. The occlusion and the facial profile were effectively improved, with good stability after fixed appliances.

summary The aim of this study was to investigate the treatment effects on the maxillofacial complex by maxillary protraction combined with chin cup therapy among growing children. An effective geometric morphometric assessment of cephalometric radiographs, using Procrustes analysis and thin-plate spline analysis, was applied to evaluate shape change in the craniofacial and midfacial configurations of a treated sample of 20 children with skeletal Class III malocclusion. This was compared with matched untreated skeletal Class III controls. Marked treatment induced change involved the maxilla and the mandible. Major deformation consisted of forward advancement of the maxillary complex with negligible rotation of the palatal plane and a forward direction of growth of the mandibular condyle associated with a restriction in sagittal advancement of the chin. Considerable dentoalveolar components contributed to the correction of anterior crossbite. Further detailed study of skeletofacial remodelling in response to maxillary protraction in other skeletal components, including the cranial base and the mandibular complex that contribute to Class III skeletal discrepancies, is warranted.

A patient with skeletal Class III malocclusion was treated in 2 phases during the early permanent dentition. In phase 1, maxillary protraction was combined with rapid palatal expansion; in phase 2, fixed appliances were placed. The results were good posttreatment, and, 1 year later, a favorable growth tendency could be observed. This report shows that treatment for a patient with skeletal Class III malocclusion can be started in the early permanent dentition, with very good final results.

The skeletal Class III malocclusion though comparatively small in incidence is one of the most difficult malocclusion to treat. It can be due to maxillary retrognathism, mandibular prognathism or both. Reverse pull Headgear or Face Mask have been used for early maxillary protraction. Face mask therapy has been shown to improve the skeletal relationship. The article presents a case report of the skeletal class III treated using a Face mask and Reverse Twin block appliance.

Objective This study investigated the treatment effects of maxillary protraction combined with chin-cap therapy in complete unilateral cleft lip and palate patients at the deciduous and early mixed dentition stages. Method Twenty-six Japanese children (10 boys and 16 girls) with complete unilateral cleft lip and palate were examined. All had undergone pushback operations for palatal repair at approximately 18 months of age. Maxillary protraction began between 5 and 7 years of age and continued for 10 to 38 months. Lateral cephalograms were used to analyze skeletal changes during the first and second years of treatment, and the relationship between pretreatment midfacial morphology and forward displacement of the maxilla during the first year was investigated. Results and Conclusions During the first year of treatment, the mean increase in the ANB angle for all cases was 2.37°. The forward displacement of the maxilla varied considerably, from 0.23 mm to 3.03 mm. The treatment response was significantly smaller in the second year, and no benefit from treatment longer than 1 year was established. The amount of maxillary forward displacement was significantly correlated with the pretreatment posterior upper facial height. Patients with smaller posterior upper facial height showed a poorer treatment response, whereas patients with a greater posterior upper facial height responded better to treatment. Individual differences in maxillary growth acceleration may be related to growth inhibition associated with post-surgical scar tissue on the palates.

This study evaluated the treatment response and posttreatment follow-up of children with Class III malocclusions treated with palatal expansion and reverse-pull face mask to the maxilla. The sample included 22 white children, 9 boys and 13 girls. Treatment began at a mean age of 9.8 years (range 5.6 to 13.3 years) and lasted 0.7 years (range 0.3 to 1.3 years). With a protraction force of 600 to 800 gm, the patients were treated until a 2 mm positive overjet had been attained. Radiographs were taken before treatment (T1), immediately after face mask treatment (T2), and 1.4 years after treatment (T3). An age and sex matched sample of untreated white schoolchildren served as normal controls. The results showed that the anterior maxilla was protracted forward 1.6 mm per year more than normal. The posterior maxilla dropped inferiorly more than the anterior maxilla. The mandible was rotated downward and backward, while the lower incisors were uprighted. The effects on the mandible were attributed to a significant chincup effect exerted by the face mask. After treatment, the maxilla relapsed relatively backward in the anterior and upward in the posterior, negating some of the treatment results. The mandible resumed a normal growth direction, and the lower incisors flared more than normal.

Four miniscrews were placed into the available inter-root area, two in the posterior and the other two in the anterior region in the maxilla as skeletal anchorage for facemask protraction in a girl 11 years and 11 months old with maxillary retrusion. No tooth support was used for the protraction of the maxilla. Applying orthopedic forces directly to the maxilla resulted in a 2 mm maxillary advancement. Undesired skeletal and dental effects of facemask therapy were eliminated with this new technique. Skeletodental changes in response to the miniscrew-anchored facemask treatment are reported in the present case.

Facemask therapy/reverse pull headgear is the popular method for maxillary protraction in maxillary deficient adolescence cases. Furthermore, various protraction methods and appliances have been developed, and evaluated extensively for their clinical efficiency. Their effectiveness enhanced with optimum orthopedic force magnitude and low-load deflection rate (LDR) and force constancy over a period of time. With the advent of NiTi springs or springs prepared from thinner wires, force decay has been markedly reduced. For use of NiTi, clinician has to depend upon prefabricated closed coil springs, which are expensive. Open-coil orthopedic traction spring (OCOTS) is developed utilizing 0.012 Australian stainless steel wire for orthopedic traction. This paper describes fabrication and clinical application of OCOTS, with numerous advantages. It sustains low LDR with optimum force magnitude. Its design is adjustable for desired length and force level. It is fail-safe for both activation and deactivation (i.e., it cannot be overstretched or over activated, and decompression limit of open-coil is also controlled by the operator).

Sixty subjects with ages ranging from 8 to 13 years were divided into two groups according to the intraoral appliances used. Group I consisted of 47 subjects with rapid palatal expansion (RPE) appliances and group II consisted of 13 subjects with labiolingual appliances (La/Li). Group I was subdivided into three subgroups by age and two subgroups by the timing of the protraction. The cephalometric radiographs of all subjects were analyzed before and after correction of anterior crossbite. The following results were obtained: (1) After maxillary protraction, the maxilla and maxillary dentitions moved forward and downward, and the mandible and mandibular dentitions moved backward and downward. (2) The maxilla moved more forward in the RPE group, compared with La/Li group. (3) The palatal plane angle decreased more in the protraction-during-palatal-expansion group than protraction-after-palatal-expansion group. (4) Age did not show any statistically significant difference.

Objective: The purpose of this study was to evaluate the validity of the 3-dimensional (3D) superimposition method of digital models in patients who received treatment with rapid maxillary expansion (RME) and maxillary protraction headgear. Methods: The material consisted of pre- and post-treatment maxillary dental casts and lateral cephalograms of 30 patients, who underwent RME and maxillary protraction headgear treatment. Digital models were superimposed using the palate as a reference area. The movement of the maxillary central incisor and the first molar was measured on superimposed cephalograms and 3D digital models. To determine whether any difference existed between the 2 measuring techniques, intra-class correlation (ICC) and Bland-Altman plots were analyzed. Results: The measurements on the 3D digital models and cephalograms showed a very high correlation in the antero-posterior direction (ICC, 0.956 for central incisor and 0.941 for first molar) and a moderate correlation in the vertical direction (ICC, 0.748 for central incisor and 0.717 for first molar). Conclusions: The 3D model superimposition method using the palate as a reference area is as clinically reliable for assessing antero-posterior tooth movement as cephalometric superimposition, even in cases treated with orthopedic appliances, such as RME and maxillary protraction headgear.

Objective: A national survey was conducted to assess orthodontic residents’ current concepts and knowledge of cleft lip and palate (CLP) management in Korea. Methods: A questionnaire consisting of 7 categories and 36 question items was distributed to 16 senior chief residents of orthodontic department at 11 dental university hospitals and 5 medical university hospitals in Korea. All respondents completed the questionnaires and returned them. Results: All of the respondents reported that they belonged to an interdisciplinary team. Nineteen percent indicated that they use presurgical infant orthopedic (PSIO) appliances. The percentage of respondents who reported they were ‘unsure’ about the methods about for cleft repair operation method was relatively high. Eighty-six percent reported that the orthodontic treatment was started at the deciduous or mixed dentition. Various answers were given regarding the amount of maxillary expansion for alveolar bone graft and the estimates of spontaneous or forced eruption of the upper canine. Sixty-seven percent reported use of a rapid maxillary expansion appliance as an anchorage device for maxillary protraction with a facemask. There was consensus among respondents regarding daily wearing time, duration of treatment, and amount of orthopedic force. Various estimates were given for the relapse percentage after maxillary advancement distraction osteogenesis (MADO). Most respondents did not have sufficient experience with MADO. Conclusions: These findings suggest that education about the concepts and methods of PSIO and surgical repair, consensus regarding orthodontic management protocols, and additional MADO experience are needed in order to improve the quality of CLP management in Korean orthodontic residents.

Titanium implants were placed surgically into the maxillary, zygomatic, frontal, and occipital bones of four pigtail monkeys. After a 4-month healing period, the implants were exposed and abutments were placed. Extraoral traction appliances were then attached to the abutments. The cranial implants were used to support the framework of the traction appliance; those in the facial bones were used to attach springs that delivered a protraction force. The application of force varied among animals. In animal A, the force was applied to the maxilla. In animal B, the force was applied to the zygomatic bones. Animals C and D had force applied to both the maxillary and zygomatic bones. A tensile force of 600 gm per side was maintained until approximately 8 mm of maxillary anterior displacement had occurred. This amount of movement required 12 weeks of force application in animals A and B, and 18 weeks in animals C and D. Cephalometric and dry skull analyses showed that the amount of skeletal protraction was significant. The findings also demonstrated that it was possible to control the direction of maxillary protraction. The facial implants remained immobile throughout the experiment.

The deformational effects on the human skull resulting from maxillary protraction were examined by means of strain gauges and displacement transducers. A maxillary protraction appliance was used that included a reverse headgear attached to the maxillary first molars. The protraction forces that were applied to this appliance were parallel to the occlusal plane at the following locations: the height of the maxillary arch, 5 mm above the palatal plane, and 10 mm above the Frankfort horizontal plane. The results indicated that protraction forces at the level of the maxillary arch produced an anterior rotation and forward movement of the maxilla, protraction forces 10 mm above the Frankfort horizontal plane produced a posterior rotation of the maxilla with a forward movement of nasion, and protraction forces 5 mm above the palatal plane produced a combination of parallel forward movement and a very slight anterior rotation of the maxilla. Moreover, constriction of the anterior part of the palate occurred in all cases.

OZET: Delaire-Verdon turu yuz maski maksillanin protraksiyonunda kullanilan etkin bir ekstra-oral ortopedik apareydir. Klinigimizde, ozellikle damak yarikli olgularda, maksiller gelisimi stimule etmek amaci ile ortopedik yuz maskindan yararlanmaktayiz. Bu yazimizda Delaire-Verdon turu yuz maskinin, hastadan alinan olcuye uygun olarak hazirlanmasi amaci ile gelistirdigimiz pratik ve ekonomik bir yapim teknigi tanitilmaktadir. Bu yontemle, hasta yuzune tam uyum saglayan ekstra-oral aparey ve gelistirdigimiz kolay uygulanabilir intra-oral ankraj sistemi, kanimizca tedavinin hasta tarafindan tolere edilebilmesini kolaylastirmaktadir.

The purpose of this study was to investigate the effect of directions of extraoral maxillary protraction forces on biomechanical changes in the craniofacial complex, using the three-dimensional finite element method (FEM). A three-dimensional FEM model was developed on the basis of a young, human dry skull. The model consisted of 2918 nodes and 1776 solid elements. An anteriorly directed 1.0 Kg force was applied to the buccal surface of the maxillary first molar in directions varying from −90 to 90 degrees to the occlusal plane. The displacement pattern of the entire craniofacial complex was evaluated. Further, the stress distributions were determined in three transverse planes associated with parallel, and 30 degrees upward and downward forces. As the force direction was more upward, repositioning of the craniofacial complex became larger in both the horizontal and vertical directions. Displacements were most translatory in loading with the forces applied in the directions ranging from −45 to −30 degrees to the occlusal plane. High stress levels were observed in the nasomaxillary complex and its surrounding structures. However, the patterns of stress distribution within the complex were different for three loading conditions. A downward protraction force produced the most uniform stress distribution. It is shown that the force direction plays an important role in determining the repositioning and the stress distributions in the craniofacial complex.

Background The aim of the present work was to evaluate the stress magnitudes and directions along the midpalatal suture in the maxillary protraction therapy. Methods The geometry of the maxilla and teeth were digitally reconstructed based on computer tomography images obtained from the skull of a girl in a mixed dentition stage with skeletal and dental class III malocclusion. An appliance commonly used for rapid palatal expansion (RPE) was also digitally modeled for anchorage of the protraction force and meshed for finite element analysis. The maxillary protraction was simulated applying 600 cN (300 cN for each side) directed 30° forward and downward to the maxillary occlusal plane. Results The principal stresses, through the force application, exhibited similar distribution patterns. A higher stress area was observed in the region of the midpalatal suture located in front of the incisive canal. All the sections showed vectors of compressive nature. Conclusions Because of the compressive nature of the stresses distributed along the midpalatal suture in the maxillary protraction therapy simulation, which is opposite to the natural growth transversal tendency, maxillary expansion is advisable in clinical cases.

The objective is to evaluate the effects of maxillary protraction by means of a bimaxillary bone anchorage as well as its progress by fixing mini plates in patients with Bilateral Cleft Lip and Palate Sequela, based on the protocol of Clerck and Cha et al. HGO CM La Raza and the Technological University of Mexico UNITEC.