American Journal of Orthodontics and Dentofacial Orthopedics最新文献

Introduction: This study aimed to investigate the polymerization shrinkage of composite attachments and changes in attachment templates during bonding in clear aligner treatments.

Methods: A total of 24 extracted teeth were divided into 4 groups, and plaster models were digitized. Attachment templates were produced with beveled attachments on premolars and rectangular attachments on molars. Polymerizations used a halogen curing light (800 milliwatts per square centimeter [mW/cm²] for 20 seconds) and light-emitting diode (LED) curing light in 3 modes (1000 mW/cm² for 20 seconds, 1000 mW/cm² for 10 seconds, and 3200 mW/cm² for 3 seconds). The curing distance was 5 mm, and temperature changes were recorded with a thermal camera. Microcomputed tomography scanning measured volumetric and linear attachments before and after polymerization. Statistical analyses employed a 1-way analysis of variance with Bonferroni corrected Tukey post-hoc for multiple comparisons and the Kruskal-Wallis test for temperature change.

Results: Significant differences (P <0.001) were found in temperature among curing lights. The highest temperature was in the LED unit-extra mode, and the lowest was in the halogen curing unit. The LED unit for 20 seconds caused the highest temperature change. A significant difference (P = 0.048) in occlusal attachment length was found between the LED unit for 20 seconds and the LED unit-extra mode. Polymerization resulted in increased attachment template thickness across all groups, with significant changes noted in the halogen unit, LED unit for 20 seconds, and LED unit-extra mode.

Conclusions: Temperature generated during polymerization varied between halogen and LED curing lights. Significant differences were found in attachment length at the occlusal level and template thickness postpolymerization. Preferences in attachment bonding protocols may affect the clinical precision of clear aligner treatments.

Introduction: This study aimed to compare and evaluate time-dependent biofilm formation and microbial adhesion on 6 different clear aligner systems: Invisalign (Align Technology, San Jose, Calif), Clarity (3M ESPE Maplewood, Minn), ClearCorrect (Institut Straumann AG, Basel, Switzerland), Smartee (Smartee Denti-Technology, Shanghai, China), Orthero (Orthero, Istanbul, Turkey) and Graphy (Graphy Inc, Seoul, South Korea).

Methods: Streptococcus mutans (ATCC 25175) and Lactobacillus acidophilus (ATCC 4356) were used to evaluate the microbial adhesion and biofilm formation on orthodontic clear aligners at the 0, 24, 48, 72, 96, 120, 168, and 240 hours. Two-way repeated measures analysis of variance (Greenhouse-Geisser) test and post-hoc Bonferroni T2 tests were used for statistical evaluation. The statistical significance level was set at P <0.05.

Results: It was found that more bacterial formation occurred on ClearCorrect than on Smartee at 120, 168, and 240 hours (P <0.05). It was observed more biofilm formation at 168 hours on Graphy than on Smartee (P <0.05). It was found that S mutans + L acidophilus formed more biofilm at 120 and 168 hours on Graphy than on Invisalign (P <0.05).

Conclusions: Elevated biofilm formation across all materials carries substantial clinical implications. Orthodontists and patients should remain aware of the increased risk of microbial colonization with extended aligner usage.

Introduction: This study aimed to (1) examine the cross-sectional area (CSA) of the masseter muscle in relation to bruxism and (2) investigate if there are gender-related differences in the masseter muscle in a population-based magnetic resonance imaging (MRI) study.

Methods: The study included 720 subjects aged 30-89 years (391 women and 329 men) from the Study of Health in Pomerania, a cross-sectional population-based study assessing the prevalence and incidence of common population-relevant diseases and their risk factors in Northeastern Germany. The participants underwent both a whole-body MRI and a full oral examination. The CSAs of the masseter muscles on both sides were measured from MRI images. The presence or absence of awake and/or sleep grinding and clenching, unilateral chewing, and other parafunctional activities were obtained from the dental interview. Linear and ordinal logistic regression models were used to examine the associations between the CSAs of the masseter, bruxism, and gender.

Results: The frequency of bruxism and reports of muscle or joint pain were significantly higher in women. The analysis revealed that a larger masseter CSA was significantly associated with bruxism only in men. The larger CSA was manifested only in the higher frequency bruxers.

Conclusions: Bruxism had heterogeneous effects on the masseter muscle between genders. Although a higher prevalence of bruxism was reported by women, the larger CSA of the masseter muscle was significantly higher in bruxing men but not in women. This study emphasizes the need for a gender-specific approach when evaluating the clinical implications of bruxism on the masseter muscle.

Introduction: The dentoskeletal effects of clear aligner treatment (CAT) with Invisalign vs temporary skeletal anchorage device-anchored Sydney intrusion spring (SIS) were compared in consecutively treated growing patients with anterior open bite using cone-beam computed tomography scans.

Methods: Fifteen adolescents treated exclusively with Invisalign, and 14 with SIS (first-phase treatment) were assessed retrospectively. Rigid-wise, voxel-based registration of pretreatment and posttreatment cone-beam computed tomography scans were performed using the anterior cranial base, maxillary plane, and mandibular body as reference regions. Treatment outcomes were compared between groups using median regression modeling.

Results: Molar intrusion and incisor extrusion (millimeters), as well as buccolingual inclination changes (°), were not expressed as prescribed in the ClinChecks for Invisalign. Both treatment modalities resulted in similar improvement of anterior open bite; however, via different mechanics. Compared with CAT, SIS demonstrated significantly greater intrusion of the maxillary first molars when measured from the mesiobuccal (16: 2.09 mm [95% confidence interval {CI}, 1.05-3.12]; 26: 2.98 mm [95% CI, 2.00-3.96]) and palatal cusps (16: 2.08 mm [95% CI, 1.15-3.01], 26: 2.83 mm [95% CI, 1.92-3.74]) and less extrusion of the maxillary incisors (12: -1.30 mm [95% CI, -2.13 to -0.47], 11: -1.30 mm [95% CI, -2.40 to -0.20], 21: -0.92 mm [95% CI, -1.73 to -0.12], 22: -0.85 mm [95% CI, -1.71 to -0.00]). There was weak evidence of association with less extrusion of the mandibular incisors using SIS. Maxillary and mandibular incisors tipped lingually in both groups with no statistical difference across groups.

Conclusions: SIS demonstrated greater maxillary molar intrusion, whereas CAT was associated with incisor extrusion.

Introduction: The primary objective of this study was to assess the 3-dimensional position of the mandibular canal (MC) in different craniofacial patterns to know about the safe placement of temporary skeletal anchorage devices using cone-beam computed tomography (CBCT). The secondary objectives were to assess sex differences and correlate the MC position with various factors.

Methods: This prospective, observational study was conducted on 90 patients, divided into 3 groups based on the sagittal pattern: skeletal Class I, Class II, and Class III. Similarly, based on the growth pattern of the patients, the sample was divided into 3 groups: horizontal, average, and vertical growth pattern. The skeletal and growth patterns were assessed using lateral cephalograms, and the position of the MC was assessed using CBCT. The position of the MC was assessed in 3 regions: the distal surface of the second molar (region 1), the interdental area between the first and second molars (region 2), and the interdental area between the first molar and second premolar (region 3). Data were subjected to statistical analysis.

Results: The statistically significant differences were noticed in the buccolingual position of MC in regions 2 and 3 in different skeletal patterns, whereas no statistically significant differences were noticed for the superoinferior position. In region 1, the MC was positioned closest to the alveolar crest among vertical growers. No statistically significant sex differences were observed between groups. A statistically significant positive correlation was observed between the buccolingual position of the MC and the skeletal pattern.

Conclusions: It is essential to know the 3-dimensional position of the MC in different craniofacial patterns using CBCT for safe placement of temporary skeletal anchorage devices.

Introduction: A novel method was established for the staging of midpalatal suture (MPS) ossification based on a pseudocoloring stack of anterior and posterior MPS coronal slices obtained by cone-beam computed tomography (CBCT).

Methods: CBCT scans of 240 subjects aged 5-35 years were pseudocolor processed. The slice thickness of stacked anterior and posterior coronal observation planes was set at 5.0 mm. The ossification status of both anterior or posterior MPS was classified as the tunnel, partially ossified, or ossified type. MPSs were classified into 5 stages: stage I, anterior and posterior MPSs are the tunnel type; stage II, anterior and posterior MPSs are the tunnel and partially ossified type, respectively; stage III, anterior and posterior MPSs are the partially ossified type; stage IV, anterior and posterior MPSs are the tunnel or partially ossified type and ossified type, respectively; and stage V, anterior and posterior MPSs are the ossified type. The weighted κ value was used to assess the intraexaminer and interexaminer agreement of the MPS classifications.

Results: Intraexaminer and interexaminer reliability of the proposed staging method was substantial. The largest proportions of patients aged 5-15 years and 16-35 years were classified as stages I and III, respectively. Among adults, 31.0% of males and 7.1% of females were classified as stage I or II.

Conclusions: The pseudocolor imaging technique and the stack of CBCT slices provide relatively intuitive and comprehensive information on MPS ossification. The novel classification of MPS ossification is expected to serve as an indication of the necessity of surgical intervention for maxillary expansion treatment.

Introduction: This study aimed to evaluate maxillary dental midline shifts and mandibular asymmetries created in different amounts and directions on photographs taken from 7 different angles by different groups and to determine acceptable esthetic limits.

Methods: Photographs of a female model in a social smile position were taken from 7 different angles (0° [frontal], 15°, 30°, and 45° on the right and left sides) and digitally modified for maxillary dental and mandibular midline deviations at specified degrees using Adobe Photoshop. To enable participants to evaluate the photographs sequentially, the photographs were transformed into videos using Adobe Premiere Pro software. The videos were rated by 188 participants (48 orthodontists; 49 dentists; 45 esthetic, plastic, and reconstructive surgeons; and 46 laypersons) using the visual analog scale (VAS) in a survey. An analysis of variance test was used to compare VAS scores among raters, and the Bonferroni test was used to compare VAS scores among the groups.

Results: The threshold for the acceptability of maxillary dental midline shifts was 2 mm for orthodontists; dentists; and esthetic, plastic, and reconstructive surgeons but 4 mm for laypersons. Although laypersons were unable to perceive changes in mandibular asymmetry between 0°-6°, the threshold was 3° for other groups. For participants in which mandibular asymmetries and maxillary dental midline shifts were in opposite directions, the threshold for all groups was 6°. For participants in which lower jaw asymmetries and maxillary dental midline shifts were in the same direction, the threshold value for orthodontists was 6°. Other groups could not perceive variables related to asymmetry.

Conclusions: More sensitive esthetic assessments can be made by evaluating smile esthetics from different angles. Mandibular asymmetries are considered more esthetically acceptable than maxillary dental midline shifts. In mandibular asymmetry and maxillary dental midline shifts, deviations in the same direction are more esthetically acceptable than deviations in opposite directions. Orthodontists are able to notice small changes in mandibular asymmetry.

Introduction: This study evaluated the dentoskeletal effects of miniscrew-anchored maxillary protraction, which included a mandibular anchorage bar and a night facemask in adolescents.

Methods: A total of 20 growing patients with Class III malocclusion and maxillary deficiency were treated with a hybrid hyrax expander with 2 miniscrews in the maxilla and a mandibular anchor bar supported in 2 miniscrews in the anterior region of the mandible. Class III elastics were used from the maxillary first molars to the mandibular anchorage bar, joining the mandibular miniscrews installed between permanent incisors and canines. The variables that met the presuppositions of a parametric analysis were analyzed using the paired t test, and the remaining variables were analyzed using the nonparametric Wilcoxon paired test.

Results: The final sample included 17 subjects (4 females and 13 males; initial age, 12.3 ± 1.2 years). The results demonstrated a significant increase in Wits appraisal (mm), ANB (°), SNA (°), N perp-A (mm), Co-A (mm), Co-Gn (mm), AFAI (mm), molar relationship (mm), overjet (mm), U6-vertical Pt (mm), L1-NB (mm) and U1-L1 (°) (P <0.05).

Conclusions: The study showed that miniscrew-anchored maxillary protraction associated with facemasks and mandibular anchorage bars produces positive skeletal effects in adolescents while also favoring the control of dental effects.

Introduction: This study aimed to assess the effect of the mandibular second molars on the stress distribution and initial displacements during leveling the curve of Spee using different archwire thicknesses and materials by means of finite element analysis.

Methods: After construction of all anatomic structures, including the mandibular alveolar bone, periodontal ligament, and dentition, 0.022-in slot brackets and 0.022 × 0.028-in molar tubes were placed on the buccal surfaces of the teeth. Different archwires were modeled, with 2 different thicknesses (0.016-in and 0.017 × 0.025-in) and 3 different materials (nickel-titanium, stainless steel, and titanium molybdenum). Two different models were created: The mandibular dentition (1) with and (2) without second molars. The initial teeth movements and periodontal ligament stress distribution after leveling were analyzed for each of the models and archwires.

Results: The initial stress levels with all archwires were higher when the second molars were also included. The highest von Mises stresses were 16.75 N/mm² with the 0.017 × 0.025-in stainless steel archwire. Periodontal stresses were mostly concentrated in the apical area of the incisors. The tendency of labial tipping increased with the attachment of second molars. Thicker archwires with all materials were noticed to enhance the anterior tipping of the incisors. In both scenarios, the least movement occurred on the x-axis.

Conclusions: The inclusion of the second molars enhanced the stress level and the initial anterior tipping of the incisors. However, the bonding of the second molars did not have any effect on the initial displacement in the transverse direction for all the archwires used. As the archwire dimension increased, higher stress values were observed on the whole mandibular dentition.

Introduction: This study aimed to evaluate the short-term and long-term skeletal and dental asymmetry with miniscrew-assisted rapid palatal expansion (MARPE), rapid palatal expansion (RPE), and control group using cone-beam computed tomography (CBCT) analysis.

Methods: A total of 180 CBCT scans were analyzed for 60 patients divided into 3 groups: MARPE (mean age 13.7 ± 1.74 years), RPE (mean age 13.9 ± 1.14 years), and control (mean age 13.3 ± 1.49 years). CBCT scans were recorded at 3 points: pretreatment (T1), postexpansion (T2), and posttreatment (T3). The anterior nasal spine, posterior nasal spine, zygomaticomaxillary point, anterior nasal cavity width, posterior nasal cavity width (PNCW), external maxillary width, palatal width, and molar inclination were measured on the left and right sides in all CBCT scans. In addition, maxillary molar width (MMW) and maxillary canine width were also evaluated on the left and right sides. Statistical analysis was performed, and the parameters were tested within the groups from T1 to T2 and T1 to T3 using a paired t test. The mean changes were then compared among the 3 groups by a mixed analysis of variance test.

Results: The RPE group showed significantly greater MMW on the left and right sides at T2 (P <0.05). MARPE and RPE led to a significant increase in the anterior nasal spine (right and left), zygomaticomaxillary point (right and left), anterior nasal cavity width (right and left), PNCW (right and left), external maxillary width (right and left), palatal width (right and left), MMW (right and left), maxillary canine width (right and left), and posterior nasal spine (left) at T2 compared with control (P <0.05). RPE led to a significant increase in the molar inclination (right and left) compared with MARPE and controls at T2. In the long term, the PNCW (right and left) was greater in MARPE compared with RPE and controls (P <0.05).

Conclusions: Within-group comparisons showed that there was no significant asymmetry in the MARPE and control group in the short and long term. The asymmetry for the RPE group was isolated to the MMW in the short term but not observed in the long term, and the magnitude of the asymmetry was clinically not significant.