Reconstruction of the pelvic girdle and hindlimb musculature of the early tetanurans Piatnitzkysauridae (Theropoda, Megalosauroidea).

Piatnitzkysauridae were Jurassic theropods that represented the earliest diverging branch of Megalosauroidea, being one of the earliest lineages to have evolved moderate body size. This clade's typical body size and some unusual anatomical features raise questions about locomotor function and specializations to aid in body support; and other palaeobiological issues. Biomechanical models and simulations can illuminate how extinct animals may have moved, but require anatomical data as inputs. With a phylogenetic context, osteological evidence, and neontological data on anatomy, it is possible to infer the musculature of extinct taxa. Here, we reconstructed the hindlimb musculature of Piatnitzkysauridae (Condorraptor, Marshosaurus, and Piatnitzkysaurus). We chose this clade for future usage in biomechanics, for comparisons with myological reconstructions of other theropods, and for the resulting evolutionary implications of our reconstructions; differential preservation affects these inferences, so we discuss these issues as well. We considered 32 muscles in total: for Piatnitzkysaurus, the attachments of 29 muscles could be inferred based on the osteological correlates; meanwhile, in Condorraptor and Marshosaurus, we respectively inferred 21 and 12 muscles. We found great anatomical similarity within Piatnitzkysauridae, but differences such as the origin of M. ambiens and size of M. caudofemoralis brevis are present. Similarities were evident with Aves, such as the division of the M. iliofemoralis externus and M. iliotrochantericus caudalis and a broad depression for the M. gastrocnemius pars medialis origin on the cnemial crest. Nevertheless, we infer plesiomorphic features such as the origins of M. puboischiofemoralis internus 1 around the "cuppedicus" fossa and M. ischiotrochantericus medially on the ischium. As the first attempt to reconstruct muscles in early tetanurans, our study allows a more complete understanding of myological evolution in theropod pelvic appendages.

Heating of metallic orthodontic devices during anti-aging treatment with vacuum and electromagnetic fields: In vitro study.

BACKGROUND: The physical appearance of an individual plays a primary role as it influences the opinion of the viewer. For this reason, orthodontic therapy to improve perceived aesthetics is in high demand among patients. This factor, combined with the increase in the number of non-invasive facial aesthetic treatments, has led to the need to understand potential risk factors in the application of medical devices to the perioral skin in patients with fixed orthodontic appliances. The aim of this study was to evaluate in vitro heating of the orthodontic bracket following electromagnetic fields and negative pressure (V-EMF) used as an anti-aging treatment. METHODS: Two different types of titanium alloy wires, one made of "beta-Titanium" alloy and the other "Ni-Ti" (DW Lingual Systems GmbH-Bad Essen-Germany) were used. The orthodontic wires and brackets mounted on a resin mouth were covered with porcine muscle tissue, then subjected to anti-aging therapy with a Bi-one LifeTouchTherapy medical device (Expo Italia Srl-Florence-Italy) which generates a combination of vacuum and electromagnetic fields (V-EMF) already adopted for antiaging therapy. During administration of the therapy, the orthodontic brackets and porcine tissue were thermally monitored using a Wavetek Materman TMD90 thermal probe (Willtek Communications GmbH-Germany). In total 20 orthodontic mouths were used, 10 with Beta Titanium wires and 10 with Nickel Titanium wires. RESULTS: A temperature increase of about 1°C was recorded in each group. The outcome of the present research shows that the absolute temperatures measured on orthodontic appliances, which, despite having a slightly different curve, both show an increase in temperature of 1.1°C at the end of the session, thus falling well within the safety range of 2°C as specified by the standard CENELEC EN 45502-1. Therefore, V-EMF therapy can be considered safe for the entire dental system and for metal prostheses, which tend to heat up at most as much as biological tissue (+0.9°C/1.1°C vs. 1.1°C/1.1°C). CONCLUSION: In conclusion, anti-aging therapy with V-EMF causes a thermal increase on orthodontic brackets that is not harmful to pulp health.

Bleaching versus color change resistant adhesive in the discoloration of bracket-bonded tooth surfaces: an in vitro study.

OBJECTIVES: The aim of this study was to compare the effect of office bleaching of teeth bonded with Transbond XTTM (3M Unitek, Monrovia, CA, USA) (TRXT) and the use of color change resistant Orthocem (FGM, Joinville, Brazil) in bracket bonding on coffee-induced enamel discoloration. MATERIALS AND METHODS: Eighty premolars were distributed in equal numbers (n = 20) to group 1 (TRXT + distilled water), group 2 (TRXT + coffee solution), group 3 (TRXT + coffee solution + bleaching), and group 4 (Orthocem + coffee solution). Color was measured using a SpectroShade Micro (MHT, International, Verona, Italy) device at the beginning (T0), after coloring (T1), after bleaching (T1B), and after debonding (T2). ΔE color change values were calculated as T1-T0, T1B-T0 and T2-T0 differences. The conformity of the data to the normal distribution was examined with the Shapiro-Wilk test. Multiple comparisons were made with Tamhane's T2 test and Tukey's HSD test using one-way analysis of variance in the comparison of normally distributed data, and multiple comparisons were made with Dunn's test using the Kruskal-Wallis H test for comparison of non-normally distributed data. The significance level was set at p < 0.050. RESULTS: A statistically significant (p < 0.001) difference was found between the T1-T0 and T2-T0 stages for group 1-4 ΔE values. A statistically significant (p < 0.001) difference was also found when the T1B-T0 ΔE values of group 3 were compared with the T1-T0 ΔE values of groups 1, 2, and 4. CONCLUSIONS: After coffee-induced enamel discoloration, bleaching of teeth bonded with TRXT produced acceptable color difference of the incisal, middle, and gingival regions of the crown. In teeth bonded with Orthocem, acceptable color difference was seen only in the middle of the crown. CLINICAL RELEVANCE: The presented study will guide the clinician on how enamel discoloration side effect of fixed orthodontic appliance can reduce.

Deep learning for virtual orthodontic bracket removal: tool establishment and application.

OBJECTIVE: We aimed to develop a tool for virtual orthodontic bracket removal based on deep learning algorithms for feature extraction from bonded teeth and to demonstrate its application in a bracket position assessment scenario. MATERIALS AND METHODS: Our segmentation network for virtual bracket removal was trained using dataset A, containing 978 bonded teeth, 20 original teeth, and 20 brackets generated by scanners. The accuracy and segmentation time of the network were tested by dataset B, which included an additional 118 bonded teeth without knowing the original tooth morphology. This tool was then applied for bracket position assessment. The clinical crown center, bracket center, and orientations of separated teeth and brackets were extracted for analyzing the linear distribution and angular deviation of bonded brackets. RESULTS: This tool performed virtual bracket removal in 2.9 ms per tooth with accuracies of 98.93% and 97.42% (P < 0.01) in datasets A and B, respectively. The tooth surface and bracket characteristics were extracted and used to evaluate the results of manually bonded brackets by 49 orthodontists. Personal preferences for bracket angulation and bracket distribution were displayed graphically and tabularly. CONCLUSIONS: The tool's efficiency and precision are satisfactory, and it can be operated without original tooth data. It can be used to display the bonding deviation in the bracket position assessment scenario. CLINICAL SIGNIFICANCE: With the aid of this tool, unnecessary bracket removal can be avoided when evaluating bracket positions and modifying treatment plans. It has the potential to produce retainers and orthodontic devices prior to tooth debonding.

Effect of fence tray matching care on excess adhesive and bracket placement accuracy for orthodontic bonding: an in vitro study.

OBJECTIVE: This study aimed to evaluate the effect of fence tray matching care (FTMC) in bracket bonding by measuring excess adhesive, as well as linear and angular deviations, and by comparing it with the half-wrapped tray (HWT). MATERIALS AND METHODS: An intraoral scanner was used to acquire data on the maxillary dental arch of a patient with periodontitis.Furthermore, 20 maxillary dental arch models were 3D printed. Using 3Shape, PlastyCAD software, and 3D printing technology, 10 FTMC (method I) and HWT (method II) were obtained. By preoperative preparation, intraoperative coordination, and postoperative measurement, the brackets were transferred from the trays to the 3D-printed maxillary dental arch models. Additionally, the bracket's excess adhesive as well as linear and angular deviations were measured, and the differences between the two methods were analyzed. RESULTS: Excess adhesive was observed in both methods, with FTMC showing less adhesive (P< 0.001), with a statistical difference. Furthermore, HWT's vertical, tip and torque, which was significantly greater than FTMC (P< 0.05), with no statistical difference among other respects. The study data of incisors, canines, and premolars, showed that the premolars had more adhesive residue and were more likely to have linear and angular deviations. CONCLUSIONS: The FTMC had higher bracket bonding effect in comparison to HWT, and the adhesive residue, linear and angular deviations are smaller. The fence tray offers an intuitive view of the precise bonding of the bracket, and can remove excess adhesive to prevent white spot lesions via care, providing a different bonding method for clinical applications.

The orthodontic treatment and the periodontal status of patients.

OBJECTIVE: Aim: To review and analyze modern professional literature on the impact of orthodontic treatment of maxillofacial anomalies on the periodontal status of patients, in particular, the subsiqent pathogenetic mechanisms of the development of periodontal diseases in this category of patients. PATIENTS AND METHODS: Materials and Methods: Bibliometric and analytical methods were used data from international scientific sources in the field of studying the impact of orthodontic treatment on the state of periodontal tissues were used. Conclusions: Patients undergoing orthodontic treatment need the increased attention to the state of periodontal tissues and regular high-quality both professional and individual oral hygiene. A comprehensive approach to treatment and preventive measures for periodontal diseases, taking into account all pathogenetic links of their development in this category of patients, aims not only to keep the periodontium healthy, but also to ensure successful completion of orthodontic treatment. Taking into account consideration the periodontal status of patients allows individual correction of the treatment plan to increase its clinical effectiveness both in the early and in the long term.

Flash-free and conventional adhesive ceramic brackets in patients undergoing orthodontic treatment: A systematic review and meta-analysis.

To investigate whether flash-free adhesive ceramic brackets (FFA) have a better clinical performance than conventional adhesive ceramic brackets (CVA) in patients undergoing multi-bracket orthodontic treatment. PubMed, CENTRAL, Web of Science, Scopus, Embase, CNKI and Grey-literature were searched without restrictions up to January 2022. Both randomized controlled trials (RCTs) and controlled clinical trials (CCTs) were included. Risk of bias assessment was performed using the RoB 2.0 and ROBINS-I cochrane risk of bias tools. Eight articles, for seven studies, were included in this systematic review, and four split-mouth trials (SMT) were included in the meta-analysis. A random-effects meta-analysis found a statistically significant faster bonding time with FFA (mean difference [MD] = -93.85 seconds/quadrant, P = .002, 2 SMT), and no statistically significant difference regarding bracket failure rate at 6 months (risk ratio [RR] = 1.05; P = .93, 3 SMT), adhesive removal time (MD = -18.26 seconds/quadrant, P = .50, 2 SMT), and amount of remnant adhesive (MD = -0.13/bracket, P = .72, 2 SMT) between FFA and CVA. No difference (P > .05, 3 SMT) was found in enamel demineralization and periodontal measurements. CVA showed a statistically significant higher debonding pain score (P = .004, 1 SMT). Both flash-free and conventional adhesive ceramic brackets had a similar clinical performance, except for the faster bonding with FFA. Further, well-designed clinical trials are still required.

Biomechanical analysis of maxillary anterior teeth movements during different retracting methods with a lever arm miniscrew system in double-slot lingual brackets: A finite element method study.

OBJECTIVE: The objective of the study was to find the most effective retracting method for the six maxillary anterior teeth with double-slot lingual brackets using a lever arm and miniscrew system. METHODS: Six finite element models were constructed: (A) a ribbon-wise archwire with a lever arm; (B) a ribbon-wise archwire with a lever arm and a sectional edgewise archwire; (C) a ribbon-wise archwire and a sectional edgewise archwire with a lever arm; (D) an edgewise archwire with a lever arm; (E) an edgewise archwire with a lever arm and a sectional ribbon-wise archwire; and (F) an edgewise archwire and a sectional ribbon-wise archwire with a lever arm. Initial displacements of maxillary teeth driven by a 1.5 N retraction force to the lever arm were analysed. RESULTS: In models B, C, E and F, anterior torque loss and inter-canine distance increases were significantly lower than that of the models without auxiliary archwires. In models C and F, the main archwire was less likely deformed. In models A, B and C, the displacement of canines in sagittal and vertical directions were less than in models D, E and F. CONCLUSIONS: The combination of edgewise and ribbon-wise archwires in double-slot lingual brackets effectively preserves the anterior arch shape. An edgewise archwire with lever arms on the auxiliary sectional ribbon-wise archwire is recommended for better performance in anterior teeth retraction.

Impact of polishing system on surface roughness of different ceramic surfaces after various pretreatments and bracket debonding.

OBJECTIVE: Evaluating various polishing methods after bracket debonding and excessive attachment material removal for different ceramics and pretreatments. MATERIAL AND METHODS: Zirconia (ZrO2), leucite (LEU) and lithium disilicate (LiSi) specimens were pretreated with a) silica coated alumina particles (CoJet); LEU and LiSi additionally with b) hydrofluoric acid (HF), c) Monobond Etch&Prime (MEP), d) silicium carbide grinder (SiC) before bracket bonding, shearing off, ARI evaluation, excessive attachment material removal and polishing with i) Sof-Lex Discs (Soflex), ii) polishing paste (Paste), iii) polishing set (Set). Before/after polishing surface roughness (Ra) was measured with a profilometer. Martens hardness parameter were also assessed. RESULTS: Irrespective of pretreatment Ra of LEU increased the most, followed by LiSi and ZrO2 (p < 0.001, SiC: p = 0.012), in accordance with the measured Martens hardness parameter. CoJet/SiC caused greater roughness as HF/MEP (p < 0.001). The ZrO2 surface was rougher after polishing with Paste/Set (p < 0.001; p = 0.047). Ra improved in the LEU/CoJet, LEU/SiC and LiSi/SiC groups with Soflex/Set (p < 0.001), in the LiSi/CoJet and LEU/HF groups by Soflex (p = 0.003, p < 0.001) and worsened by Paste (p = 0.017, p < 0.001). Polishing of HF or MEP pretreated LiSi with Set increased Ra (p = 0.001, p < 0.001), so did Paste in the LEU/MEP group (p < 0.001). CONCLUSIONS: Paste couldn't improve the surfaces. Soflex was the only method decreasing Ra on rough surfaces and not causing roughness worsening. Polishing of LEU/LiSi after MEP, LEU after HF pretreatment doesn´t seem to have any benefit. CLINICAL RELEVANCE: To avoid long-term damage to ceramic restorations, special attention should be paid to the polishing method after orthodontic treatment.

Effects of reducing excess dental adhesive on bacterial adhesion in the bracket periphery.

OBJECTIVES: White spot lesions are one of the most common side effects of orthodontic therapy with a multibracket appliance and may indicate a preliminary stage of caries, also known as initial caries. Several approaches may be utilized to prevent these lesions, such as reducing bacterial adhesion in the area surrounding the bracket. This bacterial colonization can be adversely affected by a number of local characteristics. In this context, the effects of excess dental adhesive in the bracket periphery were investigated by comparing a conventional bracket system with the APC flash-free bracket system. MATERIALS AND METHODS: Both bracket systems were applied to 24 extracted human premolars, and bacterial adhesion with Streptoccocus sobrinus (S. sobrinus) was performed for 24 h, 48 h, 7 d, and 14 d. After incubation, bacterial colonization was examined in specific areas by electron microscopy. RESULTS: Overall, significantly fewer bacterial colonies were found in the adhesive area around the APC flash-free brackets (n = 507 ± 13 bacteria) than the conventionally bonded bracket systems (n = 850 ± 56 bacteria). This is a significant difference (**p = 0.004). However, APC flash-free brackets tend to create marginal gaps with more bacterial adhesion in this area than conventional bracket systems (n = 265 ± 31 bacteria). This bacterial accumulation in the marginal-gap area is also significant (*p = 0.029). CONCLUSION: A smooth adhesive surface with minimal adhesive excess is beneficial for reducing bacterial adhesion but also poses a risk of marginal gap formation with subsequent bacterial colonization, which can potentially trigger carious lesions. CLINICAL RELEVANCE: To reduce bacterial adhesion, the APC flash-free bracket adhesive system with low adhesive excess might be beneficial. APC flash-free brackets reduce the bacterial colonization in the bracket environment. A lower number of bacteria can minimize white spot lesions in the bracket environment. APC flash-free brackets tend to form marginal gaps between the bracket adhesive and the tooth.

Effect of fluoride varnish in combination with simulated oral environment on enamel-bracket shear bond strength.

To determine the effect of fluoride varnish application combined with a simulated oral environment prior to bracket bonding on the shear bond strength (SBS) between brackets and tooth enamel. Sixty de-identified, extracted teeth were grouped to either receive or not receive fluoride varnish and then stored for 7 days at 37 °C in phosphate-buffered saline (PBS) solution or PBS combined with three 15-min cycles/day in a demineralizing solution to simulate pH variation following meals. Subsequently, brackets were bonded and after 24-h dark cure at 37 °C, debonded using shear forces in a simulated oral environment. The maximum shear force was used to calculate SBS, and the adhesive remnant index (ARI) was determined by image analysis of photos of the bracket mesh pad after debonding. A statistically higher SBS (10.16 MPa) was observed when fluoride varnish was applied prior to storage in PBS + demineralizing solution compared to SBS (6.38 MPa) following storage in the same solution without varnish application. Based on 37% effect size, this difference is also clinically relevant. In contrast, no significant differences in SBS were observed with varnish application combined with PBS with no demineralizing solution or between storage solution alone. Moreover, there was no significant difference in ARI due to varnish combined with either storage method or storage solution only. Results suggest varnish application prior to bracket bonding in combination with simulated oral environment that included acid exposure is beneficial in maintaining higher SBS between bracket and enamel. Despite higher SBS, adhesive remaining on enamel did not increase.

Effect of high-fluoride toothpaste and mouth rinse on the prevention of demineralized lesions during orthodontic treatment: a randomized controlled trial.

OBJECTIVE: To evaluate the effect of high-fluoride mouth rinse and high-fluoride toothpaste on the development of demineralized lesions (DLs) during orthodontic treatment. TRIAL DESIGN: Three-armed parallel-group randomized controlled trial. METHODS: The trial was performed with 270 adolescent orthodontic patients. Randomization was performed in blocks of 30, enrolling the patients into one of the following groups: the fluoride mouth rinse (FMR) group receiving 0.2% sodium fluoride (NaF) mouth rinse plus 1450 ppm fluoride (F) toothpaste; high-fluoride toothpaste (HFT) group receiving 5000 ppm F toothpaste; and the Control (CTR) group receiving 1450 ppm F toothpaste. Inclusion criteria were patients scheduled for treatment in both arches with fixed appliances and age between 12 and 20 years. The primary outcome variable was the proportion of participants with at least one new demineralized lesion as assessed on digital photos taken before and after treatment, analysed by a blinded clinician. The analysis included all teeth or teeth in the aesthetic zone, i.e. all central incisors, lateral incisors, and canines. A random sample of 30 participants was assessed to check intra- and inter-reliability. For pairwise comparison between groups, Fisher's non-parametric permutation test was used for continuous variables. Blinding was employed during the caries registration and data analysis. RECRUITMENT: October 2010 to December 2012. RESULTS: In total, 270 patients were randomized, of which 22 were excluded during treatment. Therefore, 248 participants were included in the study. The number of patients with an increase of ≥1 DL, including only central- and lateral incisors and canines, during orthodontic treatment, was significantly lower in the HFT group, 51/85 60%, compared to the CTR group, 64/82 78%, RR 0.77 (CI 0.62; 0.95), P = .01 and in the FMR group, 47/81 58%, compared to the CTR group, RR 0.74 (CI 0.60; 0.92), P < .01. CONCLUSIONS: To prevent demineralized lesions in the aesthetic zone, high-fluoride mouth rinse and high-fluoride toothpaste may be recommended. LIMITATIONS: The protocol was not registered, and the present study did not use a double-blinded design.

Effect of bleaching treatments on the adhesion of orthodontic brackets: a systematic review.

BACKGROUND: Nowadays bleaching procedures have gained popularity in orthodontic patients. Peroxide and Carbamide acids are the common agents which are used in in-office and at home bleaching techniques. Consequently, the Bonding adhesion to the enamel can be influenced by the orthodontic phase and the residual peroxide might interfere with the polymerization and the adhesion of the brackets. Frequent debonding of the brackets from teeth after the bleaching procedure could cause the lengthening of the therapy and promote irregularities on enamel surface derived from an additional bonding phase of the brackets. The aim of this systematic review is to appraise the influence regarding the effect of the bleaching procedure on the bond strength of orthodontic brackets. METHODS: An electronic database search was performed. Search terms included: bleaching, brackets, adhesion; data were extracted and summarized. Risk of bias was assessed using the Chocrane risk of bias tool, adapted for in vitro studies. RESULTS: A total of 8689 articles were screened and 11 studies met the inclusion criteria of this systematic review. 1000 teeth of human and bovine origin were analyzed for the shear bond strength (SBS) of stainless and ceramic brackets after the bleaching treatments. All the authors divided the groups in different subgroups with different bleaching agents and in different concentration. The SBS value allowed to demonstrate the necessity to delay the bonding of the brackets for two weeks after a bleaching treatment and its improvement when tooth mousse or antioxidants agents are used. CONCLUSIONS: The SBS values and the delay of the bonding procedure must be considered in dental practice and clinical strategies are necessary in order to avoid drawbacks which could cause the debonding of the brackets after bleaching due to the alterations of the dental substrate, thus interfering with the orthodontic treatments.

Antimicrobial efficacy of self-locomotive manganese oxide nanozyme-doped diatom microbubbler on orthodontic brackets in vitro.

BACKGROUND: Orthodontic brackets provide a favorable environment for Streptococcus mutans biofilm formation, increasing the risk of white spots and dental caries. Manganese oxide (MnO2) nanozyme-doped diatom microbubbler (DM) is a recently developed material for biofilm removal. DM can generate oxygen by catalase-mimicking activity in Hydrogen peroxide (H2O2) solution and move with ejecting oxygen microbubbles to produce a mechanical self-cleansing effect. This study aimed to evaluate the feasibility of DM as a novel bracket cleaner. METHODS: DM was prepared according to the protocol and analyzed using a scanning electron microscope (SEM). We treated S. mutans biofilms grown over bracket with phosphate-buffered saline (PBS group), 0.12% chlorhexidine (CHX group), 3% H2O2 (H2O2 group), and co-treatment with 3 mg/mL of DM and 3% H2O2 (DM group). The biofilm removal effect was analyzed using crystal violet assay, and the results were observed using SEM. The viability of S. mutans in remaining biofilms was evaluated using confocal laser scanning microscopy (CLSM). Finally, we examined the effect of all materials on mature multispecies biofilms formed on debonded brackets. RESULTS: Crystal violet assay results revealed that the CHX group removed more biofilms than the control group, and the DM group removed biofilms more effectively than the CHX group (p < 0.0001). SEM and CLSM images showed that CHX killed S. mutans but failed to remove most biofilms on brackets. However, DM effectively removed biofilms and mature multispecies biofilms on debonded brackets (p < 0.0001). CONCLUSIONS: Co-treatment with DM and H2O2 is effective in removing biofilms on orthodontic brackets compared to conventional antibacterial agents.

Comparison of microleakage under orthodontic brackets bonded with five different adhesive systems: in vitro study.

BACKGROUND: Orthodontic treatment is associated with numerous adverse side effects, such as enamel discoloration, demineralization or even caries. The presence of microleakage between the enamel and the adhesive and between the adhesive and the base of the orthodontic bracket allows penetration of the bacteria, molecules, and liquids into the enamel and can lead to unpleasant "white spot lesions" or secondary caries beneath and around the brackets. The aim of this in vitro study was to evaluate microleakage in five adhesive systems commonly used in orthodontic practice for bonding brackets. METHODS: One hundred extracted premolars were divided into five groups of twenty teeth. Stainless steel Legend medium metal brackets were bonded to teeth using five adhesive systems: resin-reinforced glass ionomer cement GC Fuji Ortho LC (GCF) and composite materials Light Bond (LB), Transbond XT (TB), Trulock™ Light Activated Adhesive (TL), and GC Ortho Connect (GCO). The specimens were subjected to thermal cycling, stained with 2% methylene blue, sectioned with low-speed diamond saw Isomet and evaluated under a digital microscope. Microleakage was detected at the enamel-adhesive and adhesive-bracket interfaces from occlusal and gingival margins. Statistical analysis was performed using generalized linear mixed models with beta error distribution. RESULTS: Microleakage was observed in all materials, with GCF showing the highest amount of microleakage. Composite materials GCO, TB, and LB exhibited the lowest amount of microleakage with no statistical difference between them, while TL showed a statistically significantly higher amount of microleakage (p < 0.001). The enamel-adhesive interface had more microleakage in all composite materials (GCO, LB, TB, and TL) than the adhesive bracket-interface (p < 0.001). The highest amount of microleakage occurred in the gingival region in all materials. CONCLUSION: Composite materials showed better adhesive properties than a resin-reinforced glass ionomer cement. The presence of microleakage at the enamel-adhesive interface facilitates the penetration of various substances into enamel surfaces, causing enamel demineralization and the development of dental caries.

Digital technique to analyze the wear of the slot after orthodontic treatment through fixed multibracket appliances.

INTRODUCTION: To assess the accuracy, repeatability and reproducibility of a measurement digital technique to quantify the wear of the bracket slot walls of the fixed multibracket appliance after orthodontic treatment with the previous measurement traditional technique (scanning electronic microscope (SEM)). METHODS: A total of 100 fixed multibracket appliances were cemented during the 15 months orthodontic treatment and subsequently removed. The fixed multibracket appliances were submitted preoperatively and postoperatively to a micro-computed tomography (micro-CT) scan to obtain accurate standard tessellation language (STL) digital files of the fixed multibracket appliances and to a preoperatively and postoperatively SEM analysis. Afterwards, pre-operatively and postoperatively STL digital files of each fixed multibracket appliances were aligned using morphometric software with the best fit algorithm. Subsequently, area and volume wear of fixed multibracket appliances was identified, isolated and measured. RESULTS: The repeatability and reproducibility of the digital measurement method for the area (mm2) and volume (mm3) were analyzed by Gage R&R statistical analysis. The area wear of the bracket slot walls of the fixed multibracket appliance after orthodontic treatment showed a repeatability of 3.7% and a reproducibility of 0%. The volume of the bracket slot walls of the fixed multibracket appliance after orthodontic treatment showed a repeatability of 0.9% and a reproducibility of 5.6%. However, the traditional measurement technique showed a repeatability of 0.58% and a reproducibility of 33.01%; hence, it was repeatable but not reproducible. CONCLUSIONS: The digital measurement technique is a reproducible, repeatable, and accurate method for quantifying the wear of the bracket slot walls of the fixed multibracket appliance after orthodontic treatment.

[Study on quantitative analysis of bracket-induced nonlinear response of labio-cheek soft tissue during the orthodontic process].

In the orthodontics process, intervention and sliding of an orthodontic bracket during the orthodontic process can arise large response of the labio-cheek soft tissue. Soft tissue damage and ulcers frequently happen at the early stage of orthodontic treatment. In the field of orthodontic medicine, qualitative analysis is always carried out through statistics of clinical cases, while quantitative explanation of bio-mechanical mechanism is lacking. For this purpose, finite element analysis of a three-dimensional labio-cheek-bracket-tooth model is conducted to quantify the bracket-induced mechanical response of the labio-cheek soft tissue, which involves complex coupling of contact nonlinearity, material nonlinearity and geometric nonlinearity. Firstly, based on the biological composition characteristics of labio-cheek, a second-order Ogden model is optimally selected to describe the adipose-like material of the labio-cheek soft tissue. Secondly, according to the characteristics of oral activity, a two-stage simulation model of bracket intervention and orthogonal sliding is established, and the key contact parameters are optimally set. Finally, the two-level analysis method of overall model and submodel is used to achieve efficient solution of high-precision strains in submodels based on the displacement boundary obtained from the overall model calculation. Calculation results with four typical tooth morphologies during orthodontic treatment show that: ① the maximum strain of soft tissue is distributed along the sharp edges of the bracket, consistent with the clinically observed profile of soft tissue deformation; ② the maximum strain of soft tissue is reduced as the teeth align, consistent with the clinical manifestation of common damage and ulcers at the beginning of orthodontic treatment and reduced patient discomfort at the end of treatment. The method in this paper can provide reference for relevant quantitative analysis studies in the field of orthodontic medical treatment at home and abroad, and further benefit to the product development analysis of new orthodontic devices.

Comparison of the effect of using panoramic and cone-beam computed tomography on the accuracy of root position in indirect digital bracket placement: A retrospective study.

OBJECTIVE: The purpose of this study was to compare the root position accuracy of the use of panoramic radiography and cone-beam computed tomography (CBCT) in the indirect digital bracket placement. METHODS: Two hundred and eighty-six maxillary and 300 mandibular teeth of 27 patients who have digital model, panoramic image and CBCT scan were included to the study. Indirect digital bonding was performed by using digital models and panoramic images in Group 1 and by superimposing the CBCT on the digital models with the OrthoAnalyzer™ 2020 (3Shape, Copenhagen, Denmark) software in Group 2. Angular measurements were calculated with 3-dimensional superimposition of the positions of the brackets placed with the Gom Inspect 2020 software. In the statistical analysis, One-way Analysis of Variance (ANOVA) and the Paired t test were used. RESULTS: Maxillary canines had the highest angular deviation at 5.56°± 4.01° in comparison with the maxillary teeth (P < .001). Mandibular canines and second premolars had the highest angular deviation in the comparison between mandibular teeth (P < .001). Considering the groups of ranges by clinical limits of the deviations, these differences were significant in the angular dimensions with 3.57° ± 2.59° (P < .001). The amount of deviation of all teeth was found 3.57° ± 2.59°in the study. CONCLUSIONS: Using panoramic images or CBCT in the digital bonding had clinical significantly effects on the angular deviation of bracket position. These findings may be taken into consideration when implementing bracket placement in indirect digital bonding. Despite the successful results, indirect digital bonding should not be the single reason to take the CBCT from the patients.

Do different orthodontic pliers used in bracket debonding have different effects on pain and sensitivity? A prospective split-mouth study.

OBJECTIVES: The assessment of whether different orthodontic pliers used in bracket debonding have different effects on pain and sensitivity experience. MATERIALS AND METHODS: Thirty-three patients (17 females, 16 males) with metal brackets were included in the study. Compressed air and freshly melted ice water were applied to each tooth (6-6) in upper and lower arch before bracket debonding (T0), just after debonding (T1), and 1 week after debonding (T2). Bracket remover plier (BRP) and Weingart plier (WP) were used to debond brackets. A numeric rating scale (NRS) was used to assess sensitivity for each tooth at T0, T1, and T2. Tooth pain was assessed for each tooth using NRS during bracket debonding. RESULTS: Statistically higher pain scores were found in teeth U4 (upper first premolar) (p = 0.017) and L6 (lower first molar) (p = 0.026) in Weingart plier group. No statistically significant difference was found during debonding in the other teeth between groups. Statistically high sensitivity score was found at T1 time point in tooth U3 (upper canine) by applying air stimulus in Weingart plier group (p = 0.024). There was no statistically significant difference between the sensitivity scores measured at T2 time point by applying air and cold stimuli between groups. CONCLUSIONS: Although the debonding pain scores were statistically significant in two teeth and the sensitivity score in one tooth, there was no clinical significance between the two pliers in terms of pain and sensitivity. CLINICAL RELEVANCE: Both debonding pliers gave clinically similar results in terms of pain and sensitivity.

Shear bond strength after using sealant before bonding: a systematic review and meta-analysis of in vitro studies.

OBJECTIVES: Decalcification during orthodontic treatment is significantly increased. To prevent this negative impact, new treatments with sealants before bonding brackets are commonly been used. This systematic review discusses current knowledge on shear bond strength when using sealant before bonding. MATERIALS AND METHODS: A systematic review and meta-analysis were performed to identify studies that address shear bond strength after using a sealant before bonding brackets. The search was carried out using common electronic databases in addition to individual searches. Both screening and study eligibility analysis were performed according to PRISMA and Cochrane Guidelines for systematic reviews. Several terms describing shear bond strength after using a sealant before bonding brackets were searched. Particular attention was paid to bond failure and bracket loss. For the statistical outcome, all results were shown in a forest plot based on standardized mean differences (SMD) with a random-effects model to respect heterogeneity of these studies. To assess the heterogeneity of the different trials, I2-value and the Q-Test were performed. RESULTS: The initial search identified 416 studies. After a thorough selection process, a total of 15 articles met the inclusion criteria. All 15 articles reported results of in vitro studies. Papers were divided into four subgroups according to their used product: ProSeal, Transbond bonding, the combination of Transbond bonding and ProSeal and Clearfil Protect Bond. The results of this review demonstrate a high heterogeneity of the studies. The SMD of the examined 15 articles show nearly no difference between the control and the intervention groups in shear bond strength (p < 0.0001; OR - 0.12; Cl - 0.47-0.23). Forest plots for comparison of the subgroups depict no difference in shear bond strength as well. CONCLUSIONS: This meta-analysis concludes that there is no additive benefit for shear bond strength when using sealant before bonding. However, additional randomized controlled studies should be performed to analyze impact of sealants on bonding strength and bracket loss in more detail. CLINICAL RELEVANCE: Using sealants before orthodontic bonding does not reduce shear bond strength.