Luis Huanca Ghislanzoni; Roberta Lione; Lorenzo Franchi; Paola Cozza
Abstract
Background: The effects of rapid maxillary expansion (RME) have been widely studied with classic bidimensional imaging.Objectives: The study aimed to determine immediate post-expansion effect of RME with three-dimensional imaging.Methods: Computed tomography (CT) low dose scan records were taken for ...
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Background: The effects of rapid maxillary expansion (RME) have been widely studied with classic bidimensional imaging.Objectives: The study aimed to determine immediate post-expansion effect of RME with three-dimensional imaging.Methods: Computed tomography (CT) low dose scan records were taken for three patients before applying RME (T0), and immediately after the end of the active expansion phase (T1). For one patient a CT scan was available also at T2, at time of RME removal. Image analysis was done in 4 steps: segmentation of the face skull, model construction and exportation of .stl surface shells, cranial base superimpositions and colorimetric maps overlay. Results: There were differences in the bone adaptations to RME, but it was possible to identify some common trends in the three patients. All of the three patients showed a pattern of forward movement of the maxilla associated to the suture opening. Patients 1 and 3 demonstrated also a downward movement of the maxilla, which was not visible on patient 2. As a sagittal advancement of almost 6 mm, as visible in patients 1 and 3, was not possible due to growth in only two weeks, all bony changes could be attributed to the RME. For patient 1, the bony changes present at T1, were still present at T2, while the suture was closed.Conclusions: A pattern of forward immediate displacement of the maxilla with respect to the cranial base was consistently noticed in three patients. The vomer bone maintained a connection with one half of the maxilla when the suture opened.
Fariborz Amini; Reyhaneh Hedayat
Abstract
Aim: The main goal of this research was to evaluate the sagittal and vertical effects of Hyrax (tooth born) and Haas (tooth-tissue born) rapid palatal expanders on dentoskeletal structures of patients with maxillary constriction characterized by bilateral posterior cross bite.
Materials and methods: ...
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Aim: The main goal of this research was to evaluate the sagittal and vertical effects of Hyrax (tooth born) and Haas (tooth-tissue born) rapid palatal expanders on dentoskeletal structures of patients with maxillary constriction characterized by bilateral posterior cross bite.
Materials and methods: A nonrondomized clinical trail of 22 patients 12 to 14 years old (mean age 12.5 years) with maxillary constriction, who were divided into two groups, was undertaken. Group-I consisted of 11 patients who received treatment by Hyrax type rapid palatal expander (RPE). Group- II composed 0111 patients who received treatment by Haas RPE. Two lateral cephalograms were taken, one before and the other after the palatal cusps of the upper posterior teeth reached the buccal cusps of lower posteriors consequent to expansion. The activation period lasted from 12-16 days with a mean value of 13.5 days. On each lateral cephalogram 8 linear and 10 angular parameters were measured, recorded and compared to a nearest of 0.5 mm and 0.5 degree respectively. Statistical analyses were performed using Kolomogrovsmirnov and paired t-test. A student t-test was used for comparison of two group.
Results: In both groups significant increases in lower anterior facial height were observed. The value (ANS-ME) was increased 1.30mm in Hyrax (P=0.009) and 1.80mm in Haas group (P=0.032). Statistically neither of the appliances showed a significant effects on sagital position of the maxilla. The mandible was rotated downward and backwards. SNB angle decreases 0.65 and 0.43 degrees in Hyrax and Haas group respectively. ANB angle was increased by means of 0.60 degree (p= 0.030) in Hyrax and 0.53 degree (p=0.08) in Haas group.
Conclussion: The maxilla kept its position sagitally, pre to post treatments, but showed inferior displacement in both groups. The mandible displayed a tendency to rotate downward and backward in both groups. Upper anteriors tipped palatally. (IJO 2006; 1: 61 - 65)
