Na-Young Chang

Root proximity and cortical bone thickness effects on the success rate of orthodontic micro-implants using cone beam computed tomography.

OBJECTIVE To evaluate factors (root proximity and cortical bone thickness) affecting the success rate of orthodontic micro-implants (OMIs) using cone-beam computed tomography (CBCT) images. MATERIALS AND METHODS We examined 172 OMIs (1.2-1.3 mm in diameter, 8 mm in length) implanted into the maxillary buccal alveolar bone of 94 patients (33 men, 61 women) with malocclusion. Root proximity and cortical bone thickness were measured, and the correlations between these measurements and OMI success rates were evaluated. RESULTS The overall success rate was 90.7% (156/172). The success rate increased as the distance between the root surface and OMI increased, showing a highly significant statistical correlation (P < .05). As the cortical bone thickness increased, the success rate increased, showing a slight, nonsignificant correlation (P > .05). Thus, the success rate of OMIs was affected more significantly by root proximity than cortical bone thickness. CONCLUSIONS When inserting OMIs, increasing the distance from the OMI to the root surface will significantly improve success rates.

Placement angle effects on the success rate of orthodontic microimplants and other factors with cone-beam computed tomography

INTRODUCTION The purpose of this study was to evaluate the effect of placement angles on the success rate of orthodontic microimplants and other factors with cone-beam computed tomography images. METHODS We examined 228 orthodontic microimplants implanted into the maxillary buccal alveolar bone of 130 patients (33 men, 97 women) with malocclusion. Vertical placement angle, horizontal placement angle, root proximity, and cortical bone thickness were measured, and the correlations between these measurements and orthodontic microimplant success rates and the correlations among the measurements were evaluated. RESULTS The overall success rate was 87.7% (200 of 228). The orthodontic microimplant success rate statistically significantly increased as root proximity (distance from the orthodontic microimplant to the root surface) increased (P <0.05), but there were no statistical significances between placement angles and success rates, and cortical bone thickness and success rate (P >0.05). Correlations between placement angles and root proximity showed no statistical significance (P >0.05), but correlations between vertical placement angle and cortical bone thickness (P <0.001) and between horizontal placement angle and cortical bone thickness (P <0.01) showed statistical significance. A statistically significant (negative) correlation was found between vertical and horizontal placement angles (P <0.001). CONCLUSIONS The success rate of orthodontic microimplants is not affected by placement angles and is more significantly affected by root proximity than by cortical bone thickness. Cortical bone thickness is affected by placement angles, but root proximity is not affected by placement angles.

Bone density effects on the success rate of orthodontic microimplants evaluated with cone-beam computed tomography.

INTRODUCTION The purpose of this study was to evaluate the effect of bone densities on the success rate of orthodontic microimplants with cone-beam computed tomography images. METHODS We examined 127 orthodontic microimplants implanted into the maxillary buccal alveolar bone of 71 patients (53 female, 18 male; mean age, 19.2 years) with malocclusion. The cortical, cancellous, and total bone densities were measured with Simplant Pro 2011 software (version 13; Materialise, Leuven, Belgium), and the correlations between these measurements and the orthodontic microimplant success rates were evaluated with cone-beam computed tomography. RESULTS The overall success rate was 85.0% (108 of 127). Sex, age, and side of placement were not significant factors for success in the results (P >0.05). The density of the cortical bone increased apically (3, 5, and 7 mm) from the alveolar crest, but in the cancellous bone it decreased. Whereas the orthodontic microimplant success rates significantly increased as cancellous bone density and total bone density increased (P <0.01), cortical bone density did not have a significant effect on the success rate (P >0.05). CONCLUSIONS The success rate of orthodontic microimplants significantly increased with higher cancellous and total bone densities, whereas cortical bone density did not have a significant effect.

Relationship between maturation indices and morphology of the midpalatal suture obtained using cone-beam computed tomography images

Objective The purpose of this study was to determine whether predicting maturation of the midpalatal suture is possible by classifying its morphology on cone-beam computed tomography (CBCT) images and to investigate relationships with other developmental age indices. Methods The morphology of the midpalatal suture was assessed by using CBCT images of 99 patients. Axial plane images of the midpalatal suture were classified into five stages according to the classification scheme. To make the assessment more accurate, the morphology and fusion of the midpalatal suture were additionally investigated on coronal cross-sectional planar images and volume-rendered images. Bone age was evaluated using the hand and wrist method (HWM) and cervical vertebrae method (CVM); dental age (Hellmans index), sex, and chronological age were also assessed. To evaluate relationships among variables, Spearmans rho rank test was performed along with crosstabs using contingency coefficients. Results The HWM and CVM showed strong correlations with the maturation stage of the midpalatal suture, while other indices showed relatively weak correlations (p < 0.01). Through crosstabs, the HWM and CVM showed high association values with CBCT stage; the HWM demonstrated slightly higher values (p < 0.0001). Based on the HWM, the midpalatal suture was not fused until stage 6 in both sexes. Conclusions Among developmental age indices, the HWM and CVM showed strong correlations and high associations, suggesting that they can be useful in assessing maturation of the midpalatal suture.

Comparison of the bonding strengths of second- and third-generation light-emitting diode light-curing units.

Objective With the introduction of third-generation light-emitting diodes (LEDs) in dental practice, it is necessary to compare their bracket-bonding effects, safety, and efficacy with those of the second-generation units. Methods In this study, 80 extracted human premolars were randomly divided into eight groups of 10 samples each. Metal or polycrystalline ceramic brackets were bonded on the teeth using second- or third-generation LED light-curing units (LCUs), according to the manufacturers’ instructions. The shear bond strengths were measured using the universal testing machine, and the adhesive remnant index (ARI) was scored by assessing the residual resin on the surfaces of debonded teeth using a scanning electron microscope. In addition, curing times were also measured. Results The shear bond strengths in all experimental groups were higher than the acceptable clinical shear bond strengths, regardless of the curing unit used. In both LED LCU groups, all ceramic bracket groups showed significantly higher shear bond strengths than did the metal bracket groups except the plasma emulation group which showed no significant difference. When comparing units within the same bracket type, no differences in shear bond strength were observed between the second- and third-generation unit groups. Additionally, no significant differences were observed among the groups for the ARI. Conclusions The bracket-bonding effects and ARIs of second- and third-generation LED LCUs showed few differences, and most were without statistical significance; however, the curing time was shorter for the second-generation unit.

Evaluation of factors influencing the success rate of orthodontic microimplants using panoramic radiographs

Objective The purpose of this study was to investigate factors influencing the success rate of orthodontic microimplants (OMIs) using panoramic radiographs (PRs). Methods We examined 160 OMIs inserted bilaterally in the maxillary buccal alveolar bone between the second premolars and first molars of 80 patients (51 women, 29 men; mean age, 18.0 ± 6.1 years) undergoing treatment for malocclusion. The angulation and position of OMIs, as well as other parameters, were measured on PRs. The correlation between each measurement and the OMI success rate was then evaluated. Results The overall success rate was 85.0% (136/160). Age was found to be a significant predictor of implant success (p < 0.05), while sex, side of placement, extraction, and position of the OMI tip were not significant predictors (p > 0.05). The highest success rate was observed for OMIs with tips positioned on the interradicular midline (IRML; central position). Univariate analyses revealed that the OMI success rate significantly increased with an increase in the OMI length and placement height of OMI (p = 0.001). However, in simultaneous analyses, only length remained significant (p = 0.027). Root proximity, distance between the OMI tip and IRML, interradicular distance, alveolar crest width, distance between the OMI head and IRML, and placement angle were not factors for success. Correlations between the placement angle and all other measurements except root proximity were statistically significant (p < 0.05). Conclusions Our findings suggest that OMIs positioned more apically with a lesser angulation, as observed on PRs, exhibit high success rates.

Mandibular condyle bone density in adolescents with varying skeletal patterns evaluated using cone-beam computed tomography: A potential predictive tool

Introduction: The aim of this study was to evaluate the bone density of mandibular condyles in adolescents with varying skeletal patterns using cone‐beam computed tomography. The null hypothesis was that there is no difference in the bone density of mandibular condyles in adolescents across various facial height ratios, ANB angle classifications, sexes, and age categories. Methods: We divided 120 adolescent patients, 56 boys and 64 girls, into 3 groups according to 3 criteria: (1) age (early, 10 to <14 years; middle, 14 to <17 years; late, 17 to <20 years); (2) facial height ratio or Jarabak quotient (hyperdivergent: facial height ratio, <62%; normovergent: facial height ratio, 62% to ≤65%; and hypodivergent: facial height ratio, >65%); and (3) ANB angle classification (Class I, 1° to ≤4°; Class II, (>4°); and Class III, <1°). The total, cortical, and cancellous bone densities were measured and compared on the axial slice with the largest mediolateral diameter of the mandibular condyle using C‐mode cone‐beam computed tomography. Results: Cortical bone density increased as age increased and showed statistically significant differences between the early and middle (P = 0.041) and the early and late adolescent groups (P = 0.031). Condylar bone density increased as facial height ratio decreased, and cancellous bone density showed statistically significant differences between the hyperdivergent and hypodivergent groups (P = 0.038). The cortical, cancellous, and total bone densities increased as ANB angle increased and showed statistically significant differences between the Class II and Class III groups (P = 0.022, P = 0.006, and P = 0.003, respectively). Conclusions: The null hypothesis was rejected. Condylar bone density increased as facial height ratio decreased and ANB angle increased. These findings may be useful in predicting the vertical and horizontal skeletal growth patterns of growing adolescents. HighlightsWe used CBCT to evaluate bone density of mandibular condyles in adolescents.Condylar bone density increased as facial height ratio decreased and ANB angle increased.ANB was a significant factor in predicting bone density.These findings may help predict vertical and horizontal skeletal growth patterns.

Effects of acid etching and calcium chloride immersion on removal torque and bone-cutting ability of orthodontic mini-implants

Introduction: The 2‐fold purpose of this study was to evaluate the effects of acid etching and calcium chloride immersion on removal torque and the bone‐cutting ability of orthodontic mini‐implants (OMIs). Methods: For the removal torque part of the study, 3 types of OMIs (titanium alloy) were evaluated in a rabbit model: OMIs with acid surface etching with and without calcium chloride immersion (ECG and EG, respectively) and a control group (CG), in which the OMIs had an untreated, machined surface. We inserted 126 OMIs (42 OMIs per type) into both tibias of 21 male rabbits (5 months of age) with body weights of 3.0 to 3.5 kg. Removal torque was evaluated after 1, 4, and 7 weeks. To determine the OMIs’ bone‐cutting ability, total insertion time to place an OMI 6 mm into artificial bone was measured (6 OMIs per group). Results: Removal torque values for the EG (3.97 ± 0.52 Ncm) and ECG (4.21 ± 0.44 Ncm) were statistically and significantly higher than those of the CG (3.02 ± 0.53 Ncm) 1 week after implantation (P <0.05). The ECG (6.54 ± 0.50, 6.61 ± 0.66 Ncm) showed the highest removal torque value followed by the EG (5.68 ± 0.58, 5.89 ± 0.70 Ncm) and CG (3.43 ± 0.62, 3.38 ± 0.54 Ncm) at 4 and 7 weeks after implantation (P <0.05). Removal torque did not change over time with the CG, but with the ECG and EG, it was significantly higher in weeks 4 and 7 than in week 1 (P <0.05). Total insertion time was significantly greater for the EG than for the ECG and CG (P <0.05). Conclusions: Treating OMIs with a calcium chloride solution improved the initial bone reaction by preventing contamination of the implant surface, and increasing the surface roughness of OMIs by acid etching enhanced their stability without decreasing the bone‐cutting ability compared with OMIs without surface treatment. HIGHLIGHTSRemoval torque and bone cutting ability of mini‐implants were investigated in rabbits.Mini‐implants were acid etched, and some were also immersed in calcium chloride.Removal torque was lower in the control group than in the acid‐etched groups.In the acid‐etched groups, removal torques were higher at 4 and 7 weeks than at 1 week.

Effectiveness of pulsed electromagnetic field for pain caused by placement of initial orthodontic wire in female orthodontic patients: A preliminary single-blind randomized clinical trial

Introduction: The purpose of this 2‐arm parallel trial was to assess the effects of pulsed electromagnetic field (PEMF) on the reduction of pain caused by initial orthodontic tooth movement. Methods: Thirty‐three female patients (mean age, 16.8 ± 3.8 years) who began orthodontic treatment using fixed appliances were examined. In the pilot study, male patients were less likely to use the PEMF device (epatchQ; Speed Dental, Seoul, Korea) and answer a survey consistently, so eligibility criteria were female patients who were periodontally and systemically healthy at the initiation of treatment and had no history of dental pain in the prior 2 weeks or who used no medications (anti‐inflammatory or analgesic drugs) during the experiment period. Each patient had brackets bonded on the maxillary teeth, and a 0.014‐in nickel‐titanium archwire was tied with elastomeric rings. Their maxillary arches were randomly divided into left and right sides in a split‐mouth design: a normal PEMF device (experimental group) was used on 1 side, and a PEMF device with an inversely inserted battery (placebo group) was used on the opposite side of the arch for 7 hours on 3 consecutive nights. A Google survey link was sent to the patients’ mobile phones via text message, and they were instructed to record their current pain on the survey. The survey was sent a total of 6 times after insertion of the initial archwire at 0 (T0), 2 (T1), 6 (T2), 24 (T3), 48 (T4), and 72 (T5) hours. Patients recorded the degree of pain in resting and clenching states using a numeric rating scale (NRS) from 1 (no pain) to 10 (worst pain). PEMF devices were used after T2. Generalized linear mixed models, along with ancillary pairwise analyses, were used to model and evaluate the differences in pain reported over 72 hours. Results: The NRS scores did not differ across the groups during the before‐PEMF phase for resting (mean difference, −0.07; 95% confidence interval [CI], −0.73 to 0.59; P = 0.842) and clenching (mean difference, −0.28; 95% CI, −1.11 to 0.56, P = 0.513). During the after‐PEMF phase, NRS scores in the experimental group were significantly lower than those in the placebo group during both resting (mean difference, −1.46; 95% CI, −2.06 to −0.85; P = <0.001) and clenching (mean difference, −1.88; 95% CI, −2.74 to −1.02, P = <0.001). The NRS scores did not differ across the groups during the before‐PEMF phase for either state but were significantly lower in the experimental group than in the placebo group at T3, T4, and T5 (P <0.01). The average NRS score in the clenching state was significantly greater than in the resting state. Conclusions: PEMF was effective in reducing orthodontic pain caused by initial archwire placement. Registration: The trial was not registered. Protocol: The protocol was not published before trial commencement. HighlightsPulsed electromagnetic field was used to relieve pain of orthodontic tooth movement.Average pain scores were greater in clenching state compared with resting state.PEMF relieved pain 24, 48, and 72 hours after placement of the initial archwires.PEMF may be effective in reducing pain caused by initial orthodontic tooth movement.

Orthodontic Treatment of Maxillary Incisors with Severe Root Resorption Caused by Bilateral Canine Impaction in a Class II Division 1 Patient

This case report shows the successful alignment of bilateral impacted maxillary canines. A 12-year-old male with the chief complaint of the protrusion of his maxillary anterior teeth happened to have bilateral maxillary canine impaction on the labial side of his maxillary incisors. Four maxillary incisors showed severe root resorption because of the impacted canines. The patient was diagnosed as skeletal Class II malocclusion with proclined maxillary incisors. The impacted canine was carefully retracted using sectional buccal arch wires to avoid further root resorption of the maxillary incisors. To distalize the maxillary dentition, two palatal miniscrews were used. After 25 months of treatment, the maxillary canines were well aligned without any additional root resorption of the maxillary incisors.