Delaram Shahbodaghi; Tahereh Hosseinzadeh Nik; Mohammad Sadegh Ahmad Akhundi; Shahab Kavousinejad; Atefe Saffar Shahroudi
Abstract
Background: Due to significant effect of joint orthodontic and surgical treatment planning on the patients’ facial appearances, precise prediction of surgical outcomes is of great importance.
Objectives: The aim of this study was to determine the maxillary and mandibular centers of rotation and ...
Read More
Background: Due to significant effect of joint orthodontic and surgical treatment planning on the patients’ facial appearances, precise prediction of surgical outcomes is of great importance.
Objectives: The aim of this study was to determine the maxillary and mandibular centers of rotation and its distance to center of condyle (CC) in patients who underwent maxillary impaction surgery concomitant with mandibular advancement or setback surgery and also to determine the correlation between maxillary center of rotation (MxCR) with that of mandible (MnCR) and also the direction of rotation in distal and proximal segments of the mandible.
Methods: Preoperative and postoperative lateral cephalograms of 24 adult non-syndromic patients were studied. Using cephalometric tracings MxCR was located as the intersection of ANS-PNS (preoperative) and ANS’-PNS’ (postoperative) lines. MnCR was located using Reuleaux method, where perpendicular bisectors of B-B’ and Go-Go’ lines meet. Using statistical analysis of correlation and comparison, all the points’ coordinates and centers of rotation were compared. Results: The average distance of MnCR to CC was 10.45 cm and the average distance of MxCR to CC was 8.39 cm. MxCR and MnCR had positive correlation in horizontal plane and they had negative correlation in vertical plane but the correlation was insignificant (P > 0.05). In addition, there seemed to be no specific pattern in the direction of mandibular proximal and distal segments’ rotations.
Conclusions: The results showed that: (1) The center of rotation calculated for mandible after bimaxillary surgery was not located within the condylar area. But generally whenever MxCR was closer to ANS, MnCR was located more anteriorly. (2) In patients with decreased distance between MxCR and SN line, MnCR would be located more superiorly. Also, whenever MxCR had greater distance from condyle, the MnCR to condyle distance was greater too. (3) The direction of rotation in proximal and distal segments of mandible had no specific pattern.
Tahereh Hosseinzadeh Nik; Toktam Jalayer; Amine Beymouri; Atefe Saffar Shahroudi; Armin Eftekhari
Abstract
Background: Third molar impaction is a major problem facing the dental profession and its impacts on the dentition has long been a major concern. Third molar is the most frequently impacted tooth. The prevalence of mandibular third molar impaction has been reported from 18 to 32 percent which varies ...
Read More
Background: Third molar impaction is a major problem facing the dental profession and its impacts on the dentition has long been a major concern. Third molar is the most frequently impacted tooth. The prevalence of mandibular third molar impaction has been reported from 18 to 32 percent which varies between populations and races.
Objectives: This study was designed to determine the best retromolar space analysis from available methods with the highest correlation with mesio-distal width of mandibular third molar (MTM) in order to predict its eruption or impaction.
Patients and Methods: Measurements were carried out on digital panoramic radiographs of 98 Iranian patients. One hundred and seventy mandibular third molars were divided into 4 groups: impacted females, impacted males, erupted females and erupted males. Twenty eight points and 24 planes were marked on the radiographs: 11 points in relation to retromolar space analysis and the mesio-distal width of MTM; and 17 points in relation to some anatomic variables assumed to be related to MTM eruption or impaction. Using these landmarks, different methods were tested for analyzing the retromolar space and its relation to the width of the MTM. Student’s t-test was applied for comparison between erupted and impacted groups and ROC curve was drawn to determine the method with the highest specificity and sensitivity.
Results: Among the performed retromolar space analysis, the method that measured the distance between distal surface of second molar and the anterior border of ramus parallel to functional occlusal plane had the highest correlation with the MTM width. Also, the impact of some anatomic factors including posterior ramus height, upper body length, etc. on MTM eruption or impaction was observed.
Conclusions: Retromolar space analysis on panoramic radiographs can be a relatively precise predictor for mandibular third molar eruption or impaction. This study also supports the multifactorial concept about third molar impaction.
Tahereh Hosseinzadeh Nik; Fatemeh Gorjizadeh
Abstract
Hemifacial macrosomia (HFM) is the second most common facial congenital anomaly. Deficiency of hard and soft tissue on one side of the face is its obvious clinical finding, which can cause facial asymmetry. Hemifacial microsomia is described in three grades of severity, although grade II has two subgroups ...
Read More
Hemifacial macrosomia (HFM) is the second most common facial congenital anomaly. Deficiency of hard and soft tissue on one side of the face is its obvious clinical finding, which can cause facial asymmetry. Hemifacial microsomia is described in three grades of severity, although grade II has two subgroups (mild and severe). Many anomalies can be misdiagnosed with different grades of Hemifacial microsomia, e.g. Treacher Collins syndrome, traumatic postnatal deformity, Goldenhar syndrome, hemi mandibular elongation, Parry-Romberg syndrome, juvenile rheumatoid arthritis, Nager acrofacial dysostosis syndrome, post axial acrofacial dysostosis, muscle dysfunction, branchio-oto-renal syndrome and Maxillofacial dysostosis. The first step to treating patients with HFM, is an accurate diagnosis. Decision making for treatment planning of patients with HFM, is highly dependent on the severity of the deformity and patients age. In mild grades of the anomaly, functional therapy can improve facial and occlusal symmetry when they are young, but in more severe grades, imposition of orthopedic treatment, may be undesirable and waste of time. Early surgical interventions to encourage the growth in the affected condyle may be helpful in severe cases; however, consultation with the surgeon is advised to determine the patients who need early surgery. Distraction osteogenesis is a controversial treatment modality, which still needs more long-term studies.
Tahereh Hosseinzadeh Nik; Elham Sadat Emdadian Razavi; Afsaneh Modarresi; Mobina Mollaei
Abstract
Introduction: A possible treatment option for non-growing patients with vertical maxillary excess (VME), is superior repositioning of maxilla with or without mandibular surgery. After maxillary impaction, mandible rotates around a center. A common assumption at the time of cephalometric prediction, is ...
Read More
Introduction: A possible treatment option for non-growing patients with vertical maxillary excess (VME), is superior repositioning of maxilla with or without mandibular surgery. After maxillary impaction, mandible rotates around a center. A common assumption at the time of cephalometric prediction, is taking condyle as an unchangeable center of rotation. Any error in determination of center of mandibular autorotation (CMA) may lead to improper jaw positioning and unaesthetic results.
Materials and methods: In this study, before and after cephalometric radiographs from fourteen orthognathic patients with maxillary impaction were evaluated.
Results: showed that center of mandibular autorotation are not similar in different patients, partly because of individualized craniofacial morphology. Therefore, precise determination of center of mandibular autorotation is necessary for obtaining ideal results.
Esfandiar Akhavan Niaki; Tahereh HosseinZadeh Nik; B. Abbasian; Sedigheh SheikhZadeh
Abstract
Background and aim: G-axis which is defined by the angle between line S-N and S-G would be of great use in evaluation of the mandibular growth relative to other craniofacial structures the aim of this study was to evaluate the correlation of G-axis with vertical parameters in adult patients of different ...
Read More
Background and aim: G-axis which is defined by the angle between line S-N and S-G would be of great use in evaluation of the mandibular growth relative to other craniofacial structures the aim of this study was to evaluate the correlation of G-axis with vertical parameters in adult patients of different malocclusions.Materials and methods: Lateral cephalograms of 90 patients with different malocclusions, were traced for evaluation of some horizontal and vertical cephalometric facial parameters. The patients were classified into three groups of 30 on the basis of clinical examination, ANB angle and wits appraisal. Pearson correlation test were conducted to compare the correlation of G axis with vertical parameters in different malocclusions.Results: Y-axis length showed significant and positive correlation with G-axis length. G-axis length and lower facial height had positive significant correlation in three categories. No significant correlation was found between G-axis length and ANB angle or wits. Conclusion: Application of the Y-axis and G-vector simultaneously seem to be more useful in cephalometric evaluation of mandibular growth pattern than emphasis on one.
Atefe Saffar Shahroudi; Amir-Hossein Mirhashemi; Hassan Noroozi; Hannane Ghadirian; Tahereh Hosseinzadeh Nik
Abstract
One of the most important characteristic of dentition is dental arch form. In orthodontic treatment, it is crucial to understand each individual dental arch for diagnosis and treatment planning and try to preserve it throughout the treatment to achieve a higher stability. Additionally, it is important ...
Read More
One of the most important characteristic of dentition is dental arch form. In orthodontic treatment, it is crucial to understand each individual dental arch for diagnosis and treatment planning and try to preserve it throughout the treatment to achieve a higher stability. Additionally, it is important to maintain a wellestablished coordination between maxillary and mandibular dental arch to have a perfect functional occlusion. In orthodontics up to now, different definitions have been proposed for human dental arch form and methods for coordinating dental arches. The aim of this study was to gather and compare these concepts. The available data were categorized and discussed in five different domains: Arch Form (history and recent concepts), Factors affecting dental arch form, Characterization of arch form, Coordination of upper and lower arches and arch wire selection and arch form.
