The current study aimed to quantify the length progression of enamel microcracks (EMCs) after debonding metal and ceramic brackets, implementing OCT as a diagnostic tool. The secondary objectives included a three-dimensional assessment of EMC width and depth and the formation of new EMCs. OCT imaging was performed on 16 extracted human premolars before bonding and after debonding. Debonding was conducted with a universal Instron machine, with ARI values recorded. Additionally, 2D and 3D OCT images were employed to detect EMC formation and progression. Enface images quantified the length, width, and number of EMCs, and the length and width were analyzed using Image J (1.54f) and MATLAB (R2014b), respectively. Sagittal cross-sectional images were used for EMC depth analysis. A paired t-test showed significant differences in the length, width, and number of EMCs after debonding (p-value < 0.05), while the Wilcoxon non-parametric test indicated significant EMC depth changes (p-value < 0.05). No significant results were identified for the EMC number in ceramic brackets and EMC depth in metal brackets. Three-dimensional OCT imaging monitored existing EMCs at higher risk of progression and detected new EMCs following orthodontic bracket debonding. This study provides novel insights into EMC progression regarding the length, width, depth, and number after debonding.

This study evaluated the fit and thickness of aligners at tooth embrasures, comparing three-dimensional (3D)-printed and thermoformed aligners. Thirty aligners—3D-printed (no-offset and 0.05 mm offset) and thermoformed—were fabricated and mounted on a maxillary dental model. All aligners were scanned using microcomputed tomography. Embrasure gap distance and thickness were measured at coronal and cervical levels, and ratios reflecting aligner fit and thickness changes after fabrication were calculated. The Kruskal–Wallis and Mann–Whitney U tests were used for group and vertical level comparisons. The 0.05 mm offset 3D-printed aligners exhibited significantly smaller embrasure gaps than the no-offset 3D-printed and thermoformed aligners, with no significant differences between coronal and cervical levels. The other groups showed larger gaps at the cervical level. The embrasure fit ratio was higher in the 0.05 mm offset 3D-printed group (73–93

This case report presents a treatment approach which combines clear aligners and skeletal anchorage, mainly micro-implants, to address crowding and lip protrusion in a middle-aged adult who presented with multiple prosthetic restorations. Tooth movements were strategically staged in a virtual setup, beginning with canine retraction using micro-implants to resolve anterior crowding, followed by en-masse distalisation of the dentition. For refinement, additional in-house aligners were employed alongside fixed auxiliaries. The total treatment duration was 9 months, demonstrating high time efficiency. Cone beam computed tomography superimposition indicated posterior tooth distalisation, slight dental arch expansion, and predominantly tipping movements of the distalised teeth. This approach of total arch distalisation rather than conventional sequential distalisation, proved to be temporally efficient against equivalent treatment results. Further research is warranted to improve biomechanical predictability and develop standardised treatment protocols.

Root movements and the rotation of a round-shaped tooth are known to be particularly challenging using clear aligners. This case report describes effective and efficient hybrid mechanics, combining aligners and a micro-implant uprighting cantilever, to correct a rotated and angulated mandibular canine. A 28-year-old male patient sought treatment for moderate crowding and presented with a severely rotated and angulated right mandibular canine, which required significant root movement to correct. Despite 12.5 months of treatment using a bracketless wire in resin slots plus clear aligners, the canine rotation and angulation remained uncorrected. Consequently, a nickel–titanium cantilever supported by a micro-implant was added to the aligner treatment. The desired mesial-out crown rotation and distal root movement of the canine occurred in 5.5 months. Adding an auxiliary cantilever when treating severely rotated and angulated teeth in clear aligner treatment is worthy of consideration.

Objectives:To assess mandibular lingual bone thickness changes after molar distalization with microimplants and during retention. Materials and Methods:Twenty-one patients (10 men, 11 women; mean age: 20.5 ± 4.9 years) who underwent mandibular molar distalization with microimplants were included. Cone-beam computed tomography images at pretreatment (T0), posttreatment (T1), and retention (T2) were used to measure posterior space available and lingual bone thickness distal to the mandibular second molar at 0-, 2-, 4-, and 6-mm levels apical to the root furcation. Repeated measures analysis of variance with Bonferroni correction was applied to compare T0, T1, and T2 measurements. Pearson's correlation analysis assessed the relationship between lingual bone thickness change and other variables. Results:The mandibular second molar moved distally by 3.0 mm at crown level, and 1.2-1.8 mm at root level, after treatment. Posterior space available decreased significantly with root-cortex contact or radiographic lingual bone dehiscence observed at 6-mm root level. After retention, reduced cortical bone thickness increased significantly; however, T2 lingual bone thickness was less than T0. Although the decrease in lingual bone thickness at 6-mm root level correlated with crown and root distal movement after treatment, the increase in bone thickness during retention was not associated with tooth movement, patient age, or retention duration. Conclusions:Mandibular lingual bone thickness noticeably decreased after molar distalization with microimplants. After retention, significant bone recovery formation was observed at the thinned lingual cortex or radiographic bone dehiscence.

Objective This study aimed to compare the validity of the mental foramen (MF) and gonion (Go) as landmarks for a mandibular horizontal plane by assessing their vertical positions and line angulations. Methods Ninety cone-beam computed tomography scans of skeletal Class III adult patients were included. The patients were divided into two main groups: symmetry (n=30) and asymmetry groups (n=60). The asymmetry group was subdivided into the roll (n=30) and non-roll types (n=30). A three-dimensional co-ordinate system was established using the best-fit mirroring superimposition of the mandibular body. Landmark positions of the MF and Go were analysed and line angulations were calculated using their coordinates. Results The Go line angulation relative to the x-axis in the mandibular co-ordinate system was significantly greater than the MF line angulation in both groups and asymmetry types (P<0.05). The difference between the Go line and the MF line angulations was significantly greater in the roll type than in the non-roll type. The bilateral vertical discrepancy in Go position was significantly greater than that of MF for both groups and asymmetry types. Conclusions The bilateral vertical discrepancy of the MF was significantly smaller than that of Go in symmetrically positioned mandibles. The mandibular roll may be assessed differently when using MF-based versus Go-based mandibular planes.

OBJECTIVES:To compare mandibular incisor compensation relative to Menton (Me) deviation between skeletal Class III patients with roll- and yaw-dominant mandibular asymmetries. MATERIALS AND METHODS:Sixty skeletal Class III patients (21.62 ± 2.69 years) with facial asymmetry were divided into roll- or yaw-dominant asymmetry groups. Mandibular skeletal and incisor measurements were carried out using cone-beam computed tomography data, and values were compared between the two asymmetry groups or between moderate and severe asymmetry subgroups using independent t-test or Mann-Whitney U-test. The relationship between skeletal and dental measurements was assessed using Pearson correlation coefficient. RESULTS:Relative to the mandibular midsagittal plane, the yaw-dominant group presented significantly greater mandibular dental midline deviation in distance (LI-mid deviation, 2.15 mm) and angulation (4.20°) toward the nondeviated side than the roll-dominant group (P < .001). The ratio of amount of LI-mid deviation to Me deviation was significantly greater in the yaw-dominant group (26.44%) than in the roll-dominant group (1.76%; P < .001). In the yaw-dominant group, the LI-mid deviation was significantly greater in the severe asymmetry subgroup than in the moderate asymmetry subgroup, and the amount of mandibular incisor compensation was positively correlated with Me deviation and mandibular yaw. CONCLUSIONS:Mandibular incisor compensation differed significantly between the roll- and yaw-dominant asymmetry groups. The yaw-dominant group demonstrated significant mandibular dental midline deviation, and dental compensation of the anterior teeth was positively correlated with Me deviation and mandibular yaw.

OBJECTIVES:To investigate the difference in labial and palatal alveolar bone thickness and height during the retention period after incisor retraction treatment with microimplant. MATERIALS AND METHODS:A sample of 21 patients (mean age: 17.80 ± 4.38 years) who underwent incisor retraction treatment using microimplants after premolar extraction was investigated. The cone-beam computed tomography images at pretreatment, posttreatment, and retention were used to measure anterior alveolar bone thickness (labial, palatal, and total; at three vertical levels) and height (labial and palatal) and differences in the incisor position during treatment or retention. Repeated-measures analysis of variance with Bonferroni correction was performed to compare the variables at T0, T1, and T2. RESULTS:The maxillary central incisor moved posteriorly by approximately 8.0 mm along with intrusive movement of 1.8 mm after treatment. The alveolar bone thickness significantly decreased on the palatal side and increased on the labial side after treatment. Thereafter, the palatal bone thickness significantly increased and labial bone thickness decreased during the retention period. The palatal interdental bone depressed by incisor retraction showed substantial bone deposition after retention. CONCLUSIONS:Radiographic palatal bone dehiscences on the incisor root and palatal bone depression between the incisor roots were apparent after treatment. This palatal bone loss around the incisor roots noticeably recovered with newly formed bone during retention.

Introduction: This study evaluated the influence of facial width on the perception of lip protrusion and investigated the concordance between 2 -dimensional (2D) profile images and 3 -dimensional (3D) video clips in assessing lip protrusion. Methods: An Asian female standard head model was created using 3D modeling software. Eight head models were constructed by modifying the standard head model in terms of facial width (broad, neutral, and slim) and lip protrusion (retrusive, straight, and protrusive). Overall, 97 Asian raters rated the lip protrusion from the 2D profiles and 3D rotation video clips of the 9 models. Results: No significant differences were found in the perception of lip protrusion in terms of sex, age, or occupation. Compared with the 2D profiles, the 3D video clips were rated as more protrusive in 8 of the 9 head models, with the retrusive broad, retrusive neutral, straight broad, and straight slim faces showing statistical significance ( P <0.01). The rating is significantly higher in slim faces than in broad faces across the 3 groups of 2D profiles ( P <0.01). For 3D video clips, the rating was higher in slim faces than in broad faces in all 3 groups, whereas differences were significant in the straight and protrusive groups only ( P <0.01). Conclusions: In this study, 3D video clips were more sensitive to the perception of lip protrusion than were 2D profiles to some extent. The lips were rated relatively more protrusive in a slim face than in a broad face. Therefore, the relationship between facial width and lip protrusion should be considered in orthodontic treatment goals and treatment plans.

Introduction: Insertion torque is the amount of torque exerted on the implant to tighten into the bone. We investigated whether insertion torque values could be correlated with the strain level in the peri-implant cortical bone resulting from mini-implant insertion. Methods: The insertion of a standard size mini-implant (phi 1.4 mm x 7 mm) into maxillary alveolar bone was simulated using the finite element method. A total of 3600 calculation steps were employed to numerically reproduce the mini-implant insertion process and analyze the insertion torque and strain distribution in bone. Special attention was given to the relationship between insertion torque values and strain level in the cortical bone at the final tightening. The strain level was quantified using the following 3 strain parameters: (1) average insertion strain, (2) peak insertion strain recorded near the mini-implant thread tips, and (3) the size of the damage zone in the cortical bone. Correlations between the insertion torque values and these 3 parameters were analyzed using linear regression. Direct proportionality and strong correlation were found between the insertion torque values and each of the 3 strain parameters: average insertion strain (r(2) = 0.91), peak insertion strain (r(2) = 0.91), and the size of damage zone (r(2) = 0.90) in the peri-implant cortical bone. Conclusions: The results of this finite element method study demonstrated that insertion torque could serve as a reliable indicator of the strain level in the peri-implant cortical bone resulting from mini-implant insertion.

Abstract Background Skeletal anchorage has made it possible to perform complex orthodontic tooth movements that are difficult or even impossible to achieve with conventional orthodontic treatment. Mandibular buccal shelf miniscrews, used for distalization, play a particularly important role in treatment of Class III malocclusion. Unfortunately, stability of the miniscrews placed in the mandible is still considered at higher risk of failure compared to other intraoral locations. The aim of our study was to determine the influence of the miniscrew size on their long-term stability, occurrence of oral mucosa inflammation and pain lasting over 48 h after implantation. Methods 184 Absoanchor® miniscrews (Dentos, South Korea) in two sizes: SH2018-10 (length 10 mm, ø 1.8–2.0 mm) and SH1514-08 (length 8 mm, ø 1.4–1.5 mm) were inserted in the mandibular buccal shelf in 92 Caucasians aged 20–50 years, diagnosed with Class III malocclusion that required en-masse distalization of the mandibular dentition. Data was statistically analyzed with the level of significance set at p = .05. Results 91.3% of the SH2018-10 and 75% of the SH1514-08 miniscrews were stable, and this difference was statistically significant (p < .05). Inflammation of the oral mucosa was noticed around both types of miniscrews and affected 50% of the SH2018-10 and 26.09% of the SH1514-08 group (p < .05). Pain lasting longer than 48 h after implantation was related to 60.87% and 20.65% of the SH2018-10 and the SH1514-08 miniscrews (p < .05), respectively. Inflammation associated with larger SH2018-10 miniscrews did not affect their stability (p > .05), contrary to the SH1514-08 ones (p < .05). When inflammation was present, the overall success rate declined to 64.29%, from 94.74% noted for TADs without inflammation. According to the log-rank test, smaller TADs failed significantly sooner than the larger ones (p = .002). Conclusion Larger SH2018-10 miniscrews are the anchorage of choice for the mandibular buccal shelf, despite triggering inflammation and long-lasting pain significantly more often than the smaller ones. Therefore, this issue should be discussed with every patient prior to miniscrew use. Trial registration ID: ClinicalTrials.gov Identifier: NCT05280678 Date of Registration: 15/03/2022. Retrospectively registered.

Abstract Background The current study aimed to evaluate factors affecting the long-term stability of microimplants using removal torque and the correlation between removal torque and clinical variables. Materials and methods This research evaluated 703 microimplants placed in 354 patients (mean age: 30.4 ± 12.1 years). The removal torque was evaluated according to various clinical variables including sex, age, placement site, microimplant size, and placement method (self-drilling versus pre-drilling). Pearson correlation and stepwise multiple linear regression analyses were performed to investigate different variables and their association with removal torque. Results The mean removal torque was significantly higher in the mandible (4.46 N cm) than in the maxilla (3.73 N cm). The values in the posterior teeth/retromolar areas were significantly higher than those in the anterior teeth area. There were no significant difference in terms of sex. Teenagers had a lower removal torque than older adults in the mandible, but not in the maxilla. Microimplants with a greater length and diameter, except for those with a greater diameter in the maxilla, was associated with a higher removal torque. Regardless of placement torque, the removal torque convergently reached approximately 4 N cm in both placement methods. The removal torque was significantly correlated with screw length in the self-drilling group and with diameter in the pre-drilling group. Conclusions Removal torque was related with placement site, age, placement method, and length and diameter of microimplants.

Idiopathic condylar resorption (ICR) is a rare, destructive temporomandibular joint disease characterised by progressive resorption of the condyles. This case report presents a record of an orthodontically treated patient with ICR with favourable posttreatment remodelling of the condyles. An 18-year-old woman sought treatment for ICR. A severe Class II high-angle facial pattern with resorption of bilateral condyles was evident. The treatment plan was determined after careful examination of condylar radiographs and comprised forward rotation of the mandible through full-arch intrusion with microimplants after extraction of the four premolars. The treatment was completed in 35 months, and the patient was noted to have a straight profile, good interdigitation and slightly increased condylar volume. Two years after retention, the condyles were stable, and the patient’s profile and occlusion remained acceptable despite a mild relapse of the mandibular position. ICR was successfully corrected with orthodontic treatment. Counter-clockwise mechanics applied during the ICR remission period not only improved facial aesthetics but were also suitable for condylar unloading.

This study was performed to identify optimal microimplant sites in the mandibular retromolar area by measurement and analysis of cortical bone thickness and density. Forty-nine records of cone-beam computed tomography were selected from 173 patients. Invivo 5.2 software was used to measure the thickness and density of 25 sites on a mesh in the mandibular retromolar area. Pearson correlation, Spearman correlation, and binary logistic regression analyses were performed to explore correlations between retromolar measurements and patient characteristics. The LSD test was used to identify optimal microimplant sites in this area. One-way ANOVA, with post hoc SNK test, was used to compare optimal microimplant sites among the retromolar area, the distobuccal bone of the second molar, and a location between the first and second molars. The mean thickness and density of mandibular retromolar cortical bone were 2.35 +/- 0.76 mm and 530.49 +/- 188.83 HU, respectively. In the mandibular retromolar area, the thickness and density of cortical bone increased from the lingual to buccal sides, and from the distal to mesial. Among 25 sites, S5C1 had the greatest thickness and density; it exhibited greater thickness and density, compared with the distobuccal bone of the second molar and the site between the first and second molars. For distal uprighting of mesially tipped molars, we recommend placement of microimplants into the retromolar distobuccal site; for distalization of mandibular dentition, we recommend placement of microimplants into the retromolar mesiobuccal site (S5C1) or 2 mm from the mesial direction of the second molar distobuccal site (B).

INTRODUCTION:This study aimed to evaluate maxillary skeletal and dental yaw in patients with skeletal Class III facial asymmetry and investigate its correlation with menton deviation. METHODS:Initial cone-beam computed tomography data from 60 patients with skeletal Class III malocclusion were used. There were 30 patients in both the symmetrical group (menton deviation <2 mm) and the asymmetrical group (menton deviation >4 mm). After reconstruction of 3-dimensional (3D) cone-beam computed tomography data, maxillary yaw and 3D positions of skeletal and dental landmarks were measured and compared between the groups. After that, correlations between menton deviation and the other variables were assessed. RESULTS:No significant difference was noted in maxillary skeletal and dental yaw between the 2 groups. In the assessment of 3D positions, translation of the maxillary bone and maxillary dentition toward the menton deviation was observed (P <0.01). Maxillary skeletal and dental yaw was not significantly correlated with menton deviation in the asymmetrical group. CONCLUSIONS:Maxillary skeletal and dental yaw was not evident in either group. Therefore, when planning maxillary surgery for patients with skeletal Class III facial asymmetry malocclusion, it may be appropriate to shift the focus of decompensation from maxillary yaw to maxillary translation.

Severe mandibular deficiency caused by temporomandibular joint (TMJ) ankyloses produces functional and aesthetic problems that require complicated long-term treatment. In this case report, we describe the benefits of using microimplant mechanics for controlling the direction of distraction during distraction osteogenesis and for performing the movement of teeth. We also present its remarkable results and long-term stability. A 20-year-old girl presented with a convex profile due to severe mandibular retrognathia after a history of several TMJ surgeries for bilateral TMJ ankyloses. Mandibular distraction osteogenesis (MDO) was performed, and elastics were placed between the microimplants to control the direction of distraction. Subsequently, after retraction of the maxillary anterior teeth and distalisation of the whole mandibular dentition, the facial profile was markedly improved, and good interdigitation was obtained. The six-year follow-up retention and overall stability were satisfactory with good interdigitation and jaw function.

Phase change and fluorescence properties of the polydiphenylacetylene derivative, poly[1-phenyl-2-(p-trimethysilyl) phenylacetylene] (PTMSDPA), were investigated according to the thermally induced phase separation (TIPS) method. 1,4-dioxane was selected as the theta solvent from solvents having solubility parameters similar to that of the polymer, and the phase diagram of the solution of PTMSDPA/1,4-dioxane was derived using the cloud-point method. A critical point appeared at a concentration of 0.88x10(-2) M and a temperature of 51.6 degrees C as the theta condition. During the cooling process, a significant fluorescence enhancement occurred near the critical point, because collision quenching and vibration relaxation in the polymer chain, which causes non-radiative emission decay, are restrained by the abrupt phase separation between the polymer and the solvent. This study provides a tentative method for producing highly fluorescent nanoparticles and microporous membranes by applying TIPS to fluorescent conjugated polymers.