Korean Journal of Orthodontics最新文献

Objective: This study aimed to evaluate the association between low tongue position (LTP) and the volume and dimensions of the nasopharyngeal, retropalatal, retroglossal, and hypopharyngeal segments of the upper airway.

Methods: A total of 194 subjects, including 91 males and 103 females were divided into a resting tongue position (RTP) group and a LTP group according to their tongue position. Subjects in the LTP group were divided into four subgroups (Q1, Q2, Q3, and Q4) according to the intraoral space volume. The 3D slicer software was used to measure the volume and minimum and average cross-sectional areas of each group. Airway differences between the RTP and LTP groups were analyzed to explore the association between tongue position and the upper airway.

Results: No significant differences were found in the airway dimensions between the RTP and LTP groups. For both retropalatal and retroglossal segments, the volume and average cross-sectional area were significantly greater in the patients with extremely low tongue position. Regression analysis showed that the retroglossal airway dimensions were positively correlated with the intraoral space volume and negatively correlated with A point-nasion-B point and palatal plane to mandibular plane. Males generally had larger retroglossal and hypopharyngeal airways than females.

Conclusions: Tongue position did not significantly influence upper airway volume or dimensions, except in the extremely LTP subgroup.

Objective: The aim of this study was to determine whether an association between study quality, other study characteristics, and Altmetric Attention Scores (AASs) existed in orthodontic studies.

Methods: The Scopus database was searched to identify orthodontic studies published between January 1, 2017, and December 31, 2019. Articles that satisfied the eligibility criteria were included in this study. Study characteristics, including study quality were extracted and entered into a pre-pilot data collection sheet. Descriptive statistics were calculated. On an exploratory basis, random forest and gradient boosting machine learning algorithms were used to examine the influence of article characteristics on AAS.

Results: In total, 586 studies with an AAS were analyzed. Overall, the mean AAS of the samples was 5. Twitter was the most popular social media platform for publicizing studies, accounting for 53.7%. In terms of study quality, only 19.1% of the studies were rated as having a high level of quality, with 41.8% of the studies deemed moderate quality. The type of social media platform, number of citations, impact factor, and study type were among the most influential characteristics of AAS in both models. In contrast, study quality was one of the least influential characteristics on the AAS.

Conclusions: Social media platforms contributed the most to the AAS for orthodontic studies, whereas study quality had little impact on the AAS.

Objective: To determine whether the gonial angle on digital panoramic radiographs is associated with vitamin D receptor (VDR) Taql polymorphism.

Methods: Genomic DNA samples were collected from the buccal mucosa of patients aged 26-43 years. TaqMan assay for single nucleotide polymorphism genotyping was used to detect the genotype of Taql polymorphism. The gonial angle was measured bilaterally on panoramic radiography. The normal gonial angle was fixed as 121.8°, and it represented the cutoff value for the high gonial angle (HGA) and low gonial angle (LGA) groups. Various genetic models were analyzed, namely dominant (homozygous [AA] vs. heterozygous [AG] + polymorphic [GG]), recessive (AA + AG vs. GG), and additive (AA + GG vs. AG), using the chi-squared test.

Results: The reliability of the gonial angle measurement was analyzed using a random sample (26%) of the tests, with the intra-examiner correlation showing an intra-class correlation coefficient of 0.99. The frequencies of the AA, AG, and GG genotypes of rs731236 polymorphism were 40.5%, 41.9%, and 17.6% in the HGA group and 21.8%, 51.0%, and 27.2% in the LGA group, respectively (P = 0.042). A statistically significant difference was observed in the allele frequencies between the two groups (P = 0.011). Moreover, a significant correlation was observed in the dominant genetic model.

Conclusions: Taql polymorphism in the VDR gene plays a critical role in the vertical growth of the mandible and decreased gonial angle.

Objective: To evaluate the effects of an electric toothbrush with vibrational frequencies of 125 Hz and 150 Hz on the orthodontic tooth movement (OTM) rate and the production of prostaglandin E2 (PGE2).

Methods: Out of thirty patients (aged 18-25 years; 16 females and 14 males), ten patients each formed Group A and B, who used electric toothbrushes with 125 Hz and 150 Hz vibrations, respectively. The remaining ten patients (Group C) served as the control group and did not use electric toothbrushes. The rate of OTM and levels of PGE2 using microcapillary pipettes were calculated before the start of retraction (T0), on the 30th day (T1), on the 60th day (T2), and on the 90th day (T3) from the start of retraction in all the groups.

Results: There was a statistically significant difference in the mean OTM values and PGE2 levels in all three groups at different time intervals, with the maximum difference seen in Group B compared to Group A and least in Group C at T1, T2 and T3.

Conclusions: The rate of OTM and levels of PGE2 were highest in patients who used an electric toothbrush with 150 Hz mechanical vibration compared to those who used an electric toothbrush with 125 Hz mechanical vibration and least in patients who did not use an electric toothbrush. Mechanical vibration led to an increase in the PGE2 levels and accelerated the OTM.

Objective: The aim of this retrospective study was to compare changes in hard tissue and soft tissue after the four first premolars were extracted with anterior teeth retraction according to the presence or absence of lip incompetence.

Methods: Patients who underwent the four first premolars were extracted with anterior teeth retraction were divided into competent (n = 20) and incompetent lip (n = 20) groups. Cephalometric measurements for hard tissue and soft tissue changes were performed pre-treatment and post-treatment.

Results: In the competent group, the upper and lower lips retreated by 2.88 mm and 4.28 mm, respectively, and in the incompetent group by 4.13 mm and 5.57 mm, respectively; the differences between the two groups were significant (p < 0.05). A strong positive correlation between retraction of the upper lip and upper incisors was observed in both groups (p < 0.05), whereas a correlation between retraction of the lower lip and lower incisors was only found in the incompetent group. A simple linear regression analysis showed that the pattern of lip retraction following the retraction of the anterior teeth was more predictable in the incompetent group than in the competent group.

Conclusions: These findings suggest that the initial evaluation of lip incompetence in patients with skeletal Class II is essential for the accurate prediction of the soft tissue changes following retraction of the anterior teeth in premolar extraction treatment. Therefore, sufficient explanation should be provided during patient consultations.

Objective: This study aimed to clarify differences in the positions of cone-beam computed tomography (CBCT) landmarks according to different midsagittal planes (MSPs) in patients with skeletal Class III facial asymmetry.

Methods: Pre-treatment CBCT data from 60 patients with skeletal Class III were used. The patients were classified into symmetric (menton deviations of < 2 mm) or asymmetric (menton deviations of > 4 mm) groups. Six MSPs were established based on previous studies, and three-dimensional analyses were performed for the planes in both the groups. The measurement outcomes were compared statistically.

Results: A statistically significant interaction (p < 0.01) was observed between MSPs and facial asymmetry. No significant differences were observed among MSPs in the symmetric group. However, significant differences in linear measurements were identified among MSPs in the asymmetric group. Specifically, the upper facial MSP revealed both maxillary and mandibular transverse asymmetries. On the other hand, anterior nasal spine (ANS)-associated MSP could not identify maxillary asymmetry. Furthermore, the menton deviation was approximately 3 mm lower when estimated using the ANS-associated MSP than that using upper facial MSP.

Conclusions: The choice of MSP can significantly affect treatment outcomes while diagnosing patients with asymmetry. Therefore, care should be taken when selecting MSP in clinical practice.

Objective: The evidence on the accuracy of bite registration using intraoral scanners is sparse. This study aimed to develop a new method for evaluating bite registration accuracy using intraoral scanners.

Methods: Two different types of models were used; 10 stone models and 10 with acrylic resin teeth. A triangular frame with cylindrical posts at each apex (one anterior and two posteriors) was digitally designed and manufactured using three-dimensional (3D) printing. Such a structure was fitted in the lingual space of each maxillary and mandibular model so that, in occlusion, the posts would contact their opposing counterparts, enforcing a small interocclusal gap between the two arches. This ensured no tooth interference and full contact between opposing posts. Bite registration accuracy was evaluated by measuring the distance between opposing posts, with small values indicating high-accuracy. Three intraoral scanners were used: Medit i500, Primescan, and Trios 4. Viewbox software was used to measure the distance between opposing posts and compute roll and pitch.

Results: The average maximum error in interocclusal registration exceeded 50 μm. Roll and pitch orientation errors ranged above 0.1 degrees, implying an additional interocclusal error of around 40 μm or more. The models with acrylic teeth exhibited higher errors.

Conclusions: A method that avoids the need for reference hardware and the imprecision of locating reference points on tooth surfaces, and offers simplicity in the assessment of bite registration with an intraoral scanner, was developed. These results suggest that intraoral scanners may exhibit clinically significant errors in reproducing the interocclusal relationships.

Objective: This study aimed to evaluate the zygomaticotemporal suture (ZTS) maturation, analyze the age distribution patterns of ZTS maturation stages, and investigate the relationship between ZTS and cervical vertebral maturation (CVM).

Methods: A total of 261 patients who underwent cone-beam computed tomography (112 males, mean age, 13.1 ± 3.3 years; 149 females, mean age, 13.7 ± 3.1 years) were examined to evaluate the ZTS stages. The ZTS stages were defined based on a modified method from previous studies on zygomaticomaxillary sutures. Differences between groups and correlations between indicators were analyzed using the Spearman correlation test, intraclass coefficient of correlation (ICC), one-way analysis of variance and rank sum test. Statistical significance was set at p < 0.05. The diagnostic value of CVM stages in identifying ZTS maturation stages was evaluated using positive likelihood ratios (LRs).

Results: A positive relationship was found between the ZTS and CVM stage (r = 0.747, ICC = 0.621, p < 0.01) and between the ZTS stage and chronological age (r = 0.727, ICC = 0.330, p < 0.01). Positive LRs > 10 were found for several cervical stages (CSs), including CS1 and CS2 for the diagnosis of stage B, CS1 to CS3 for the diagnosis of stages B and C, and CS6 for the diagnosis of stages D and E.

Conclusions: The ZTS maturation stage may be more relevant to the CVM stage than to the chronological age. The CVM stages can be good indicators for clinical decisions regarding maxillary protraction, except for CS4 and CS5.