INTRODUCTION:
The aim of this study was to test the null hypothesis that increased irregularity of the mandibular incisors is associated with a reduction in the alveolar support on cone-beam computed tomographic sections.
METHODS:
From a sample of 1100 digital volumetric tomographs, 125 tomographs of subjects with Class I malocclusion (mean age, 21.6 ± 4.8 years) were selected for this study. An irregularity index was used to categorize these tomographs as having mild, moderate, or severe crowding. All tomographs were taken by using an iCAT (Imaging Sciences International, Hatfield, Pa) imaging device. The following parameters we . . .re measured on the sections corresponding to the 4 mandibular incisors with the iCAT software: height, thickness, and area of the entire symphysis; height, thickness, and area of the cancellous bone of the symphysis; and distance between the vestibular and lingual cortices. For the statistical evaluation, independent samples t test, analysis of variance, and the Tukey HSD test were used at an alpha level 0.05. The Pearson correlation coefficient and a simple linear regression were calculated to determine the relationship between mandibular anterior bony support and incisor crowding.
RESULTS:
Almost all mandibular anterior bone measurements were greater in the male subjects than in the female subjects (height of the mandibular symphysis, P
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Objective: To test the hypotheses that (1) there is no difference in mandibular asymmetry between
the crossbite and normal side in a unilateral crossbite group (UCG) and between the right and left
sides in a bilateral crossbite group (BCG) and a control group (CG); and (2) there is no significant
difference in mandibular asymmetry among crossbite groups and control group.
Materials and Methods: The cone-beam computed tomography scans of three groups were
studied: (1) 15 patients (6 male, 9 female; mean age: 13.51 6 2.03 years) with unilateral posterior
crossbite; (2) 15 patients (8 male, 7 female; mean age: 13.36 6 2.12 years) . . . with bilateral posterior
crossbite; and (3) 15 patients (8 male, 7 female; mean age: 13.46 6 1.53 years) as a control group.
Fourteen parameters (eight linear, three surface, and three volumetric) were measured. Side
comparisons were analyzed with paired samples t-test, and for the intergroup comparison, analysis
of variance (ANOVA) and Tukey tests were used at the P , .05 level.
Results: According to side comparisons, no statistically significant difference was found in the
UCG. There were statistically significant differences in hemimandibular (P 5 .008) and ramal (P 5
.004) volumes for the BCG and in ramal height (P 5 .024) and body length (P 5 .021) for the CG.
Intergroup comparisons revealed significant differences in hemimandibular (P 5 .002) and body
volume (P , .001) for the normal side of the UCG and left sides of the other groups, and in angular
unit length (P 5 .025) and condylar width (P 5 .007) for the crossbite side of the UCG and the right
sides of the other groups.
Conclusions: Contrary to UCG, CG and BCG were found to have side-specific asymmetry.
Skeletal components of the mandible have significant asymmetry among the crossbite groups and
the CG
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Objective: To determine whether there is any difference between the cleft and non-cleft sides of the mandible
in unilateral cleft lip and palate (UCLP) patients, or the right and left sides in control patients; and
to determine if there is any difference between the mandibular asymmetry of UCLP patients and that of
control patients. Methods: We examined cone-beam computed tomography (CBCT) scans of 15 patients
with UCLP and 15 age- and gender-matched control patients. We evaluated 8 linear, 3 surface, and 3 volumetric
measurements and compared the cleft/non-cleft sides of UCLP patients and the right/left sides of
controls. Res . . .ults: There were no statistically significant gender differences in any linear, surface, or volumetric
measurement. The single significant side-to-side difference in UCLP patients was a longer coronoid
unit on the cleft side than on the non-cleft side (p = 0.046). Body volume was significantly lower in the
UCLP group than in the control group (p = 0.008). Conclusions: In general, UCLP patients have symmetrical
mandibles, although the coronoid unit length is significantly longer on the cleft side than on the
non-cleft side. UCLP patients and controls differed only in body volume
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Objective: To test the null hypothesis that the presence of alveolar defects (dehiscence and
fenestration) was not different among patients with different vertical growth patterns.
Materials and Methods: A total of 1872 teeth in 26 hyper-divergent (mean age: 24.4 6 4.8 years),
27 hypo-divergent (mean age: 25.1 6 4.5 years), and 25 normo-divergent (mean age: 23.6 6
4.1 years) patients with no previous orthodontic treatment were evaluated using cone-beam
computed tomography. Axial and cross-sectional views were evaluated with regard to whether
dehiscence and/or fenestration on buccal and lingual surfaces existed or not. For stat . . .istical
analysis, the Pearson chi-square test was used at a P , .05 significance level.
Results: According to the statistical analysis, the hypo-divergent group (6.56%) had lower
dehiscence prevalence than the hyper-divergent (8.35%) and normo-divergent (8.18%) groups
(P 5 .004). Higher prevalences of dehiscence and fenestration were found on buccal sides in all
vertical growth patterns. While fenestration was a common finding for the maxillary alveolar region,
dehiscence was a common finding in the mandible in all groups.
Conclusion: The null hypothesis was rejected. Although the prevalence of fenestrations was not
different, significant differences for dehiscences were found in patients with different vertical growth
patterns
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Objective: To evaluate the root resorption after rapid maxillary expansion (RME) via cone-beam
computed tomography (CBCT).
Materials and Methods: Records of 25 patients who had undergone RME with tooth-borne
banded expander were obtained from the archive of the orthodontic department. CBCT data were
reconstructed with surface and volume rendering, and the volumetric images were manipulated to
display the root surfaces from various orientations. On these three-dimensional images, permanent
first molars and first and second premolars were segmented, and their roots were isolated.
Volumes of roots were calculated. The difference . . . between pre-expansion and postexpansion root
volumes was statistically evaluated with a paired-samples t-test. Also, the percentage of root
volume loss was calculated for each root and statistically compared with each other with one-way
analysis of variance at the P , .05 level.
Results: The difference between the pre-expansion and postexpansion root volumes was
statistically significant for all roots investigated. Maximum volume decrease was observed for the
mesiobuccal root of first molar teeth (18.60 mm3). It was determined that the distobuccal root of first
molar teeth was less affected from the expansion procedure (9.47 mm3). No statistically significant
difference was found for the percentage of root volume loss.
Conclusion: Following RME treatment, significant root volume loss was observed for all
investigated posterior teeth. However, the percentage of volume loss was not statistically different
among roots. (Angle Orthod. 2012;82:488–494.
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Objective: To evaluate the changes in cortical bone thickness, alveolar bone
height, and the incidence of dehiscence and fenestration in the surrounding
alveolar bone of posterior teeth after rapid maxillary expansion (RME) treatment
using cone-beam computed tomography (CBCT). Methods: The CBCT records of
20 subjects (9 boys, mean age: 13.97 ± 1.17 years; 11 girls, mean age: 13.53 ±
2.12 year) that underwent RME were selected from the archives. CBCT scans had
been taken before (T1) and after (T2) the RME. Moreover, 10 of the subjects had
6-month retention (T3) records. We used the CBCT data to evaluate the buccal
and . . . palatal aspects of the canines, first and second premolars, and the first
molars at 3 vertical levels. The cortical bone thickness and alveolar bone height
at T1 and T2 were evaluated with the paired-samples t-test or the Wilcoxon
signed-rank test. Repeated measure ANOVA or the Friedman test was used to
evaluate the statistical significance at T1, T2, and T3. Statistical significance was
set at p < 0.05. Results: The buccal cortical bone thickness decreased gradually
from baseline to the end of the retention period. After expansion, the buccal
alveolar bone height was reduced significantly; however, this change was not
statistically significant after the 6-month retention period. During the course
of the treatment, the incidence of dehiscence and fenestration increased and
decreased, respectively. Conclusions: RME may have detrimental effects on the
supporting alveolar bone, since the thickness and height of the buccal alveolar
bone decreased during the retention period
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Objective: This study aimed at evaluating the changes in mandibular arch widths and buccolingual inclinations of mandibular posterior teeth after rapid maxillary expansion (RME). Methods: Baseline and post expansion cone-beam computed tomographic (CBCT) images of patients who initially had bilateral posterior cross-bite and underwent RME with a banded type expander were assessed in this study. The patients included 9 boys (mean age: 13.97 1.17 years) and 11 girls (mean age: 13.53 2.12 years). Images obtained 6 months after retention were available for 10 of these patients. Eighteen angular and 43 linear measurements were performed f . . .or the maxilla and mandible. The measurements were performed on frontally clipped images at the following time points; before expansion (T1), after expansion (T2), and after retention (T3). Statistical significance was assessed with paired sample t test at 0.05. Results: T1 T2 comparisons showed statistically significant post RME increases for all measurements; similarly, T2 T1 and T3 T1 comparisons showed statistically significant changes. The maxillary linear and angular measurements showed decreases after expansion, and mandibular linear and angular measurements increased after retention. Conclusion: All mandibular arch widths increased and mandibular posterior teeth were uprighted after RME procedure
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Introduction: The aim of this study was to determine the peri-miniscrew implant crevicular fluid receptor
activator of nuclear factor-lB ligand (RANKL) and osteoprotegerin (OPG) levels around loaded and unloaded
miniscrew implants at different time intervals. Methods: Twenty loaded and 16 unloaded miniscrew implants
were included in this study. All miniscrew implants were placed bilaterally between the maxillary second premolars
and first molars as anchorage units for canine distalization. Peri-miniscrew implant crevicular fluid was taken
from the mesiobuccal aspects of the loaded and unloaded miniscrew implants before loading; . . . at 24, 48, and 168
hours; and on day 30 after force application. Enzyme-linked immunosorbent assay kits were used to determine
RANKL and OPG levels in the peri-miniscrew implant crevicular fluid samples. Wilcoxon, Mann-Whitney U, and
Spearman correlation tests were used for statistical evaluations at the P\0.05 level. Results: Although the total
amount of OPG was not different between the groups, the total amount of RANKL was significantly elevated in
the loaded miniscrew implant group (P\0.05) at all time periods. Peri-miniscrew implant crevicular fluid volume
was the highest at 48 hours in the loaded group. Also, the OPG/RANKL ratio in the peri-miniscrew implant
crevicular fluid was significantly decreased in the loaded miniscrew implant group. Conclusions: The OPG
and RANKL levels vary around loaded and unloaded miniscrew implants as a result of force application
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