• 대한구순구개열학회지
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• 제15권2호
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• pp.51-60
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• 2012

Craniofacial sutures absorb the stress transferred to skull. It was reported the cells of craniofacial sutures respond to exogenetic factors to be involved in growth control mechanism. In this study, we constructed a finite element model composed of cortical bone, cancellous bone, suture, PDL, and teeth by using CT images of a growing patient, simulating maxillary expansion to evaluate the effects of the thickness of sutures and type of maxillary expansion appliance on stress distribution in circummaxillary sutures.

• 대한치과교정학회지
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• 제41권3호
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• pp.200-210
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• 2011

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: $13.97{\pm}1.17$ years) and 11 girls (mean age: $13.53{\pm}2.12$ years). Images obtained 6 months after retention were available for 10 of these patients. Eighteen angular and 43 linear measurements were performed for 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 $p$ < 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.

• 대한치과교정학회지
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• 제43권2호
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• pp.83-95
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• 2013

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: $13.97{\pm}1.17$ years; 11 girls, mean age: $13.53{\pm}2.12$ 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.

• 대한치과교정학회지
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• 제42권5호
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• pp.235-241
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• 2012

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.

• 대한치과교정학회지
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• 제34권1호
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• pp.23-31
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• 2004

본 연구의 목적은 다수의 연구들로부터 추출한 각각의 결과를 체계적이고 객관적인 방법으로 병합, 개관하는 통계분석법인 메타분석을 이용하여 상악확장술에서의 견치간 폭경과 대구치간 폭경의 확장 및 급속과 완속 확장에서의 확장량과 재발량을 비교하는 것이었다. 메드라인 검색을 통해 1979년부터 2000년까지의 문헌들 중 사람을 대상으로 상악확장술의 효과에 관해 조사한 문헌 388개를 찾은 후 논문 선택 및 제외 범주에 따라 최종적으로 7개의 문헌을 선정하여 메타분석을 시행하여 다음과 같은 결과를 얻었다. 1. 상악확장술에 의한 상악 제 1대구치간 폭경은 평균 6.0mm의 확장되었으며, 보정 후 측정에서 평균 4.8mm가 유지되어 평균 $20.0\%(1.2mm)$의 재발경향을 보였다. 2. 상악 견치간 폭경은 제 1대구치간 폭경의 확장보다 2.3mm적은 평균 3.7mm확장되었으며, 보정 후 측정에서 평균 2.6mm가 유지되어 평균 $29.7\%(1.1mm)$의 재발경향을 보였다. 3. 급속 상악확장술과 완속 상악확장술의 치료효과의 차이는 확장량과 보정 후 재발량 및 유지량에서 $6\%$ 미만(0.1-0.3mm)이었다. 그러나 상악 견치간 및 제1대구치간 폭경 변화에 있어서 두 방법 간에 골격성 및 치성 확장량의 비율에서 차이가 있을 수 있다.

• Imaging Science in Dentistry
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• 제43권2호
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• pp.85-90
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• 2013

Purpose: This study was performed to determine the buccal alveolar bone thickness following rapid maxillary expansion (RME) using cone-beam computed tomography (CBCT). Materials and Methods: Twenty-four individuals (15 females, 9 males; 13.9 years) that underwent RME therapy were included. Each patient had CBCT images available before (T1), after (T2), and 2 to 3 years after (T3) maxillary expansion therapy. Coronal multiplanar reconstruction images were used to measure the linear transverse dimensions, inclinations of teeth, and thickness of the buccal alveolar bone. One-way ANOVA analysis was used to compare the changes between the three times of imaging. Pairwise comparisons were made with the Bonferroni method. The level of significance was established at p<0.05. Results: The mean changes between the points in time yielded significant differences for both molar and premolar transverse measurements between T1 and T2 (p<0.05) and between T1 and T3 (p<0.05). When evaluating the effect of maxillary expansion on the amount of buccal alveolar bone, a decrease between T1 and T2 and an increase between T2 and T3 were found in the buccal bone thickness of both the maxillary first premolars and maxillary first molars. However, these changes were not significant. Similar changes were observed for the angular measurements. Conclusion: RME resulted in non-significant reduction of buccal bone between T1 and T2. These changes were reversible in the long-term with no evident deleterious effects on the alveolar buccal bone.

• 대한치과교정학회지
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• 제34권6호
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• pp.526-536
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• 2004

본 연구는 급속상악확대술 시행 후 보정기간중에 지대치의 압박측 치근흡수에 불화나트륨의 경구 투여가 영향을 미치는지를 알아보기 위하여 시행되었다. 이차성징을 아직 나타내지 않은 10마리 소아기 암캐에 견치를 주지대치로 사용하는 주조형 상악 확대장치를 제작, 장착하였다 상악확대장치는 20일간에 걸쳐 5mm 확장시켰으며, 교합면 방사선사진을 이용하여 정중구개봉합의 이개를 확인하였다. 실험동물은 실험군 5 마리와 대조군 5 마리로 나뉘었으며, 보정기간 중 실험군에는 2.2 mg/kg/day의 불화나트륨 (불소로서 1.0mg/kg/day)을 캅셀제의 형태로 1 일 2 회로 나누어 단독 경구 투여하였다. 실험동물들을 보정 후 0 일, 15 일, 30 일, 45 일, 및 60 일째에 각 군당 한 마리씩 배정하여 충분한 마취로 희생시킨 후 상악골을 절취하였다. 이후 실험동물의 좌측 상악 견치의 압박측 치근표면과 압박측 견치 협면을 덮고 있던 골 조직의 치아측 표면을 주사전자현미경을 이용하여 관찰하였다. 본 실험에서 압박측 치근표면을 관찰한 결과 45일 보정군과 60일 보정군의 대조군에서 흡수소와가 발현되는 빈도가 높았다. 지대치 압박측 치근을 덮는 골면에 나타나는 흡수소와의 발현은 30일의 보정기간 이후부터 실험군에서 적게 나타남을 알 수 있었다. 차후 급속상악확대술을 시행하는 경우 효과적인 NaF의 투여시기와 용량에 대한 검증이 필요하리라 생각된다.

• 한국정밀공학회지
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• 제27권2호
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• pp.40-49
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• 2010

The Purpose of this paper is to weld a rapid palatal expander using a continuous wave Nd:YAG laser. The rapid palatal expander has become a useful treatment method for severe maxillary transverse deficiencies and posterior crossbites. Rapid maxillary expansion is a well-established method to correct transverse maxillary deficiency and arch length discrepancy. The major process parameters studied in the present laser welding experiment were the positions of focus, laser power and travel speed of laser beam. We measured the fusion zone size and its shape using an optical microscope for the observation of cross-sectional area and tension stress of a rapid palatal expander welded. Through the experimental investigation, the optimum speeds and power of laser without deficiencies of weld cross-sectional area were obtained.

• 대한치과교정학회지
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• 제54권1호
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• pp.59-68
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• 2024

Objective: To investigate the long-term effects of maxillary skeletal expander (MSE) treatment on functional breathing. Methods: Objective measures of breathing, the peak nasal inspiratory flow (PNIF), and peak oral inspiratory flow (POIF), and subjective measures of breathing, the visual analog scale (VAS) and nasal obstruction symptom evaluation (NOSE) survey, were used to investigate the long-term effects of MSE in functional breathing. Seventeen patients, mean age 19.4 ± 3.9 years treated at the UCLA Orthodontics Clinic were assessed on their functional breathing at 3 timepoints: pre-expansion (T0), post-expansion (T1), and post-orthodontic treatment (T2). Results: Immediately after expansion (T1), all the objective functional breathing values were significantly increased in comparison to T0 (P < 0.05). The VAS total, VAS right and VAS left were significantly lower at T1 in comparison to T0 (P < 0.05). At 26.8 ± 3.9 months after MSE expansion (T2), PNIF total, PNIF right, PNIF left, and POIF were significantly higher when compared to T0 (P < 0.05). Also, VAS total, VAS right and VAS left were significantly lower at T2 when compared to T0 (P < 0.05). Additionally, there was a positive correlation between PNIF and the magnitude of expansion at anterior nasal spine and zygomaticomaxillary point (ZMA). There was a positive correlation between total VAS and the magnitude of expansion at the ZMA. There were no significant changes for the NOSE subjective breathing measurement at all time comparisons. Conclusions: Overall, MSE treatment produces an increased objective and subjective airway improvement that continues to remain stable in the long-term post expansion.

• 대한치과교정학회지
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• 제49권4호
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• pp.235-245
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• 2019

Objective: This study examined bone microstructure restoration after rapid maxillary expansion (RME) with and without corticotomy over multiple retention periods. Methods: Eighteen male Dorper sheep were randomly distributed into three groups (n = 6 each group): group 1, RME with corticotomy on the buccal and palatal sides; group 2, conventional RME treatment; and group 3, no treatment. Post-RME, trabecular bone microstructure and new bone formation were evaluated by using microcomputed tomography (microCT) and histomorphometry after a 4- or 12-week retention period. Intergroup differences in bone quality and bone remodeling were analyzed by using two-way analysis of variance with Bonferroni post-hoc test. Results: The bone volume fraction (bone volume [BV]/total volume [TV]) values relative to the control in groups 1 and 2 were 54.40% to 69.88% after the 4-week retention period and returned to approximately 80% after the 12-week retention period. The pooled BV/TV values of the banded teeth in groups 1 and 2 were significantly lower than those of the control after the 4-week retention period (p < 0.05). However, after the 12-week retention period, the pooled BV/TV values in group 2 were significantly lower than those in groups 1 and 3 (p < 0.05). Histomorphological analysis showed that the new bone formation area in group 1 was approximately two to three times of those in group 2 and control. Conclusions: Corticotomy significantly enhanced the restoration of bone quality after the retention periods for banded teeth. This benefit might result from the increased new bone formation after corticotomy.