Forward Movement Of Maxilla Research Articles

The effects of 3-D Screw on the nasomaxillary complex in skeletal class III malocclusion

Aim of the study is to evaluate the Stress distribution and displacement of various structures of nasomaxillary complex with 3- D screw in skeletal class III malocclusion. An analytical model was developed from a human skull of a 15-year-old male. CT scan images of the skull were taken in axial direction parallel to the F-H plane, which was processed using Mimics software, required portion of the skull & 3-D screw appliance was converted into geometric model using reverse engineering technique. ANSYS software was used to solve the mathematical equation. Contour plots of the displacement and stresses were obtained from the results of the analysis performed. Maximum transverse displacement was 3.18mm at the permanent first maxillary teeth. Maximum antero-posterior displacement was 1.26mm at the anterior part of zygomatic bone and 1.35mm of displacement frontozygomatic suture. maximum vertical displacement was 2.81 mm representing the inferior and medial portion of the nasal bone and indicating downward displacement. Pyramidal displacement of maxilla was evident. Apex of pyramid faced towards nasal bone and base was located on the oral side. There was downward, forward movement of maxilla with a tendency toward posterior rotation. Maximum von Mises stresses were found along midpalatal, zygomaticomaxillary, nasomaxillary, frontozygomatic sutures.

Association between Lateral Cephalometric Changes in X-Y Coordinate System and Profile Changes among Skeletal Class III Patients after Orthognathic Surgery.

BACKGROUNDSince aesthetic issues are the most important causes of referring skeletal class III patients to surgeons, investigating the impact of orthognathic surgeries on improving patient profiles increases the quality of treatment and quality of life. METHODSIn a retrospective observational-analytical study, 25 patients older than 18 years with class III skeletal malocclusion who had gone under both orthodontic and double-jaw orthognathic treatment were enrolled. Cephalometric imaging interval was before and at least 6 months after surgery. By defining a number of points and coordinate axes (X-Y), a criterion for comparing hard and soft tissue changes was obtained. These measurements were coordinated, linear and angular. The quantitative data were compared with data obtained using the Likert Scale Questionnaire by means of electronic “Google Forms” that was completed by orthodontists (n=5) and maxillofacial surgeons (n=5) to rank improvement in post-surgical profiles for both cephalometry and photography from poor to pleasant. Spearman Correlation Analysis was conducted between the quantitative and qualitative data.RESULTSVertical changes of point B and horizontal changes of point PNS showed correlation with improvement of patient profile. Changes in N-Pog line (R=-0.4), mandibular plane angle (R=-0.4) and nasolabial angle (NLA) (R=0.38) were significantly correlated with improvement of profiles. CONCLUSIONIn orthognathic double-jaw surgery on patients with skeletal Class III, forward movement of maxilla, upward positioning of mandible (decreasing anterior facial height), decreasing mandibular plane angle and increasing nasolabial angle would result in a better profile.

Stability of orthodontic treatment in the patients with cleft lip and palate

Severe maxillary deficiency is often seen in cleft lip and palate patients due to multiple factors such as congenital defect, traumatic effect of surgeries and constriction of scar tissue, which causes moderate to severe crowding and anterior and posterior crossbite. Orthodontic treatment is usually difficult and time consuming. Upper arch expansion and maxillary protraction are often carried out to release transverse and sagittal intermaxillary discrepancy. Orthodontic treatment for cleft patients is different from that of non-cleft patients. Special management is needed and the stability of treatment should be considered. Relapse usually occurred after upper arch expansion especially in canine and premolar area. Over expansion should be cautious and orthognathic surgery may reduce the unstability of expansion. Maxillary protraction can improve the facial esthetics of the children with cleft. Alveolar bone grafting could improve the protraction effect and reduce the side effect such as clockwise mandibular rotation and upper incisor proclination. Forward movement of maxilla by protration is stable and continuous growth of the mandible is the most liable factor causing relapse. High mandibular angle and over growth of mandible are the risk factors of unstability of maxillary protraction.

Effective treatment plan for maxillary protraction: Is the bone age useful to determine the treatment plan?

A major skeletal effect of reverse-pull headgear is a forward movement of maxilla, via remodeling of the circummaxillary sutures. We hypothesized that an evaluation of bone age would help to determine the effective planning and optimum timing using reverse-pull headgear. Differences in the cephalometric measurements between the initiation of treatment and after 1 year of treatment were calculated from 60 Japanese patients in mixed dentition with skeletal Class III malocclusions. Bone age was appraised by the Tanner-Whitehouse 2 method using hand-wrist radiographs at the initiation of treatment. The control groups (mean chronologic age, male 10.3 years and female 9.6 years) were treated by lingual arch and/or chincup, and the reverse-pull headgear groups (mean chronologic age, male 9.7 years and female 9.4 years) by reverse-pull headgear. The forward movement of the maxilla and increase in the palatal length were larger in the bone age-based younger male reverse-pull headgear subgroup than in the bone age-based older male reverse-pull headgear subgroup. The increase of SNA in the male reverse-pull headgear group was significantly larger than that of the female reverse-pull headgear group, which had a more mature skeletal status than the former. In the male reverse-pull headgear group, the forward movement of the maxilla and increase in the palatal length showed significant inverse correlation with the bone age, but not with the chronologic age. These results support our hypothesis that the bone age is a useful clinical indicator to determine the effective treatment plan with reverse-pull headgear. (Am J Orthod Dentofacial Orthop 2000;118:55-62)

Intercanine Widening and Sagittal Effect of Maxillary Transverse Expansion in Patients with Cleft Lip and Palate during the Deciduous and Mixed Dentitions

Since 1977 cleft lip and palate (CLP) patients with maxillary deficiency have received an interceptive orthopedic treatment consisting of (a) transverse expansion, (b) protraction, and (c) fixed retention. Ideally the treatment should be completed early enough to permit spontaneous eruption of the maxillary permanent incisors into normal occlusion without orthodontic intervention. The early transverse expansion considerably increases space so that unerupted malpositioned incisors spread out spontaneously, creating optimal conditions for eruption and root formation. Dental diagnosis in the cleft areas is made easier. Posterior crossbites in 112 CLP patients were expanded with a modified quad-helix appliance cemented with four bands in the deciduous or mixed dentition. Intercanine widening was about 3 mm per month regardless of cleft type. Several authors have claimed that transverse expansion of the upper jaw will increase sagittal overjet. Other authors have not found such an effect. The sagittal effect on the maxilla was studied in 68 CLP patients who had received transverse expansion. Analysis of the lateral cephalograms revealed no significant sagittal dentofacial maxillary treatment effects involving forward movement of maxilla, but a downward clockwise rotation of the mandible was found.