Basal and dentoalveolar transverse parameters in different sagittal and vertical malocclusions in adults: a comparative study.

OBJECTIVE: This study sought to three-dimensionally (3D) evaluate the maxillomandibular basal bone and dentoalveolar widths using cone-beam computed tomography (CBCT) scans in adult Chinese populations with different vertical and sagittal facial skeletal patterns whilst no apparent posterior dental crossbite. MATERIALS AND METHODS: The retrospective cross-sectional comparative study enrolled CBCT images of 259 adult patients (125 males and 134 females). The subjects were divided into the hyperdivergent(n = 82), hypodivergent(n = 88), and normodivergent(n = 89) groups based on the Jarabak ratio (S-GO/N-Me), which were further divided into three subgroups of skeletal Class I, II and III, based on both the ANB angle and AF-BF parameters. ANOVA was used to analyze the extracted data of the studied groups. The intra- and inter-observer reliability was analyzed using the intra-class correlation coefficient (ICC). RESULTS: In all three vertical facial skeletal patterns, the skeletal Class II had significantly smaller mandibular basal bone width compared to skeletal Class I and Class III, both at the first molar and first premolar levels. The skeletal Class III seemed to have smaller maxillary basal bone width compared to skeletal Class I and Class II malocclusions; however, a significant difference was found only in the normodivergent pattern. As for the dentoalveolar compensation, it was most notable that in the hypodivergent growth pattern, the skeletal Class II had significantly smaller maxillary dentoalveolar width compared to the Class I and Class III groups, both at the first molar and first premolar levels. CONCLUSIONS: Based on the sample in the present study, skeletal Class II has the narrowest mandibular basal bone regardless of the vertical facial skeletal pattern. CLINICAL RELEVANCE: For Chinese adults with no apparent transverse discrepancy, the maxillomandibular basal bone and dentoalveolar widths are revealed in specific categories based on different vertical and sagittal facial skeletal patterns. In diagnosis and treatment planning, particular attention should be paid to skeletal Class II for possibly existing mandibular narrowing.

Tridimensional Analysis of Incisive Canal and Upper Central Incisor Approximation.

OBJECTIVE: The present study aimed to estimate the location of the incisive canal (IC) concerning the upper central incisor roots (U1) in order to explore the amount of incisor retraction as per the envelope of discrepancy amongst Chinese patients with different vertical facial growth patterns. METHODS: This is a cross-sectional study that used a total of 207 pretreatment cone-beam computed tomography (CBCT) scans of adults with a skeletal class I relationship. Sixty-nine cases were included in each of the normodivergent, hypodivergent, and hyperdivergent facial groups. The IC volume was measured using Mimics 21 software. The IC width and IC-U1 proximity were measured using in vivo 6 software. Linear measurements were conducted at 3 vertical levels. RESULTS: The IC has shown a larger volume in the hyperdivergent group and male patients. Overall, the IC has recorded linear width greater than the inter-root distance of U1 in 59.1%, 66%, and 68.8% amongst the normodivergent, hypodivergent, and hyperdivergent facial groups, respectively, and in 58.3% of males and 70.8% of females. The overall sagittal distances between the U1 and IC were 4.00 ± 0.82 mm, 4.60 ± 0.83 mm, and 3.60 ± 0.80 mm amongst the normodivergent, hypodivergent, and hyperdivergent facial groups, respectively. CONCLUSIONS: The maximum sagittal distances between U1 and IC were 4.8 mm, 5.4 mm, and 4.4 mm amongst the normodivergent, hypodivergent, and hyperdivergent facial groups, respectively. Thereby, our findings have revised the retraction aspect of the envelope of discrepancy as per the different vertical facial growth patterns, which could serve a reference for the clinical practice involved considerable incisors movement, especially among Chinese patients.

The effect of orthodontic vertical control on the changes in the upper airway size and tongue and hyoid position in adult patients with hyperdivergent skeletal class II.

BACKGROUND: At present, there are still controversies about the influence of orthodontic treatment on the size of upper airway and the position of hyoid bone. We investigated the effect of orthodontic vertical control therapy on the size of the upper airway and position of the tongue and hyoid bone in adult patients with hyperdivergent skeletal Class II. METHODS: Overall, 15 adults with hyperdivergent skeletal Class II and normal occlusion, respectively, were selected as the experimental and control groups. The angle and line of the craniofacial structure, upper airway, hyoid bone position and three-dimensional (3D) upper airway indexes were measured using the Uceph 4.2.1 standard version and Mimics 21.0 software, respectively. The paired t-test, Wilcoxon symbol rank test, t-test of two independent samples, two independent sample nonparametric tests, Mann-Whitney U test, Pearson correlation analysis, the Univariate linear regression analysis and Multiple linear regression analysis were performed. RESULTS: After treatment, the S-Go/N-Me (%) and the MP-SN and XiPm-SN angles were significantly different (P < 0.01). The U-MPW and PAS significantly increased (P < 0.05), sagittal diameter L2 increased significantly, and transverse diameter L2 decreased significantly (P < 0.01). Although no significant correlation was observed between the vertical change in the jaw and that in U-MPW and PAS, the sagittal diameter L2 showed a significant correlation (P < 0.05). The Multiple linear regression analysis showed that there was a significant negative correlation between the variables MP-SN and sagittal diameter L2 and positive correlation between S-Go/N-Me(%) and H-MP (P < 0.05). Furthermore, significant differences between the Hv (P < 0.01) and sagittal diameter L1(P < 0.05) were observed before and after treatment. CONCLUSIONS: After the orthodontic vertical control therapy in patients with hyperdivergent skeletal Class II, the upper airway only underwent adaptive changes during treatment without substantial size changes, the position of tongue body and hyoid bone did not change significantly. Furthermore, compared with normal occlusion, the velopharyngeal segment airway of patients with hyperdivergent skeletal Class II remains narrow and long after treatment.

Qualitative and quantitative three-dimensional evaluation of maxillary basal and dentoalveolar dimensions in patients with and without maxillary impacted canines.

BACKGROUND: This study aimed to three-dimensionally evaluate the qualitative and quantitative maxillary basal, dentoalveolar, and dental dimensions in patients with unilateral or bilateral maxillary impacted canines relative to their normal peers. MATERIALS AND METHODS: This is a retrospective comparative study. Cone-beam computed tomography images of one hundred and fifty adult patients were divided into three equal groups: unilateral, bilateral, and control groups. Each had 50 patients that were three-dimensionally analysed. The quantitative measurements involved three basal (molar basal width, premolar basal width, and arch depth), seven dentoalveolar (molar alveolar width, premolar alveolar width, inter-molar width, inter-premolar width, inter-canine width, arch length, and arch perimeter), and two dental (canine length and width) measurements. The qualitative measurements included four bone density areas (buccal, lingual, mesial, and distal) around the maxillary impacted canines. RESULT: Differences between the three groups were statistically different for the quantitative measurements involving the two basal variables (molar basal width and premolar basal width) and all measured dentoalveolar variables; these were smaller in the unilateral and bilateral groups compared with the control group (p < 0.001). Unilateral and bilateral impacted canine groups showed significantly wider and shorter canines than the control group (p < 0.001). The qualitative measurements (the four bone density areas) around unilateral and bilateral impacted canine groups showed significantly greater density than the control group (p < 0.001). There was no significant qualitative or quantitative difference between the unilateral and bilateral impacted canines. The three groups had no significant variations in terms of arch depth. CONCLUSION: Maxillary unilateral and bilateral canine impactions are associated with reduced basal and dentoalveolar dimensions as well as wider and shorter maxillary canines compared to normal peers. The quality of bone around unilateral and bilateral impacted maxillary canines is higher than in non-impacted cases. Unilateral and bilateral canine impactions have quite similar qualitative and quantitative parameters.

Preparation and characterization of Y-doped microarc oxidation coating on AZ31 magnesium alloys.

The rapid degradation characteristics of magnesium alloys limit its application in the field of orthopedic fracture fixation and cardiovascular stents. This study aimed to improve the corrosion resistance and biocompatibility of AZ31 magnesium alloys and prepare degradable implant materials. Micro-arc oxidation (MAO) was used to change the concentration of yttrium acetate in the electrolyte to prepare coatings with different yttrium content on the surface of AZ31 magnesium alloy. Through characterization, it is proved that the yttrium in the coating mainly exists in the form of Y3+. The polarization potential experiment shows that the micro-arc oxidation coating significantly improves the corrosion resistance of magnesium alloys. With the increase of yttrium acetate concentration in the electrolyte, the corrosion resistance of the coating first increases and then weakens. When the concentration is 0.0035 mol/L, the coating has the highest corrosion resistance. The results of CCK-8 cytotoxicity experiment and cell morphology observation also proved that the cell viability in each group was greater than 140%, and the yttrium-doped coating on the surface of AZ31 magnesium alloy has no cytotoxicity, can promote cell growth, and has good biocompatibility.

Three-dimensional assessment of the favorability of maxillary posterior teeth intrusion in different skeletal classes limited by the vertical relationship with the maxillary sinus floor.

BACKGROUND: Understanding the anatomical relationship between the maxillary sinus floor (MSF) and the posterior maxillary teeth (PMT) is important when planning the orthodontic intrusion of the posterior teeth. This study aimed to determine the vertical relationship between posterior maxillary teeth and maxillary sinus floor in different skeletal classes in the Chinese adult population. METHODS: This is a retrospective cross-sectional study involved cone beam computed tomography images of 298 adult patients (145 males and 153 females) between 20 and 45 years old. The sample was categorized according to A point, Nasion, B point (ANB) angle into 102 Class I, 102 Class II, and 94 Class III malocclusion. Non-parametric Wilcoxon Mann-Whitney U and Kruskal-Wallis tests were used to compare the studied groups. The Intra-class Correlation Coefficient (ICC) was used to assess the intra- and inter-observer reliability analysis. RESULTS: Overall, there was a statistically significant difference in the mean distance between both genders (P < 0.001). The measured distance increased with age in all posterior tooth roots (P < 0.001). The root apex in the sagittal view appeared to be closer to the maxillary sinus than in the coronal view; 2.2 ± 4.3 and 3.1 ± 5.5 mm, respectively. The most frequent root scores were Type 1 and Type 2P. In both sagittal and coronal views, Class I demonstrated a higher Type 2P prevalence, whereas Class III showed a lower prevalence. The second molars' mesiobuccal root had the largest number of penetration in the three examined skeletal classes. CONCLUSIONS: Maxillary molars of Class I malocclusion with the majority of Type 2P root-sinus relationship have the highest possible risk of root resorption during molar intrusion due to cortical bone encroachment, while Class III malocclusion showed the least possible risk.

Three-dimensional assessment of the favorability of maxillary posterior teeth intrusion in different facial patterns limited by the vertical relationship with the maxillary sinus floor.

OBJECTIVE: Posterior teeth intrusion is one of the best treatment options for treatment of skeletal open bite in adults; the surrounding anatomical landmarks are one of the restraining factors. This study aimed to assess the vertical relationship between the maxillary posterior teeth (MPT) and the maxillary sinus floor (MSF) in different facial growth patterns in the Chinese adult population. MATERIALS AND METHODS: Cone beam computed tomography images of 298 patients, 145 males and 153 females aged between 20 and 45 years, were analyzed. Based on Jarabak ratio and the mandibular plane inclination, the sample was categorized into 94 hyperdivergent, 102 hypodivergent, and 102 normodivergent facial patterns subjects. The vertical relationship between the root-apex distances were classified as favorable, indicating no contact (type 1), or unfavorable, indicating roots in contact (type 2) for the posterior teeth intrusion. The relationship in the unfavorable group was subdivided into three subgroups (T2C, T2LC, and T2P). Comparative statistical tests were done related to age, gender, tooth side, and type of multiplanar view (sagittal and coronal). The significant level was set to be P < 0.05. RESULTS: There was a statistically significant difference in the mean distance between both genders in the hyperdivergent group (P < 0.001). The measured distance increased with age in all tooth roots (P < 0.001). In both sagittal and coronal views, the most frequent root scores were type 1 and type 2p (54.2%, 27.5%) and (55.1%, 21.4%), respectively. The hyperdivergent group demonstrated a higher prevalence of type 2P (31.6% and 25.5%), whereas the hypodivergent group showed a lower prevalence (25.1% and 19.2%); furthermore, the second molar's mesiobuccal root in hyperdivergent patients showed the closest distance to the maxillary sinus in sagittal and coronal views, 0.3 ± 3.7 and 0.4 ± 3.1 mm, respectively. CONCLUSIONS: Maxillary molars of hyperdivergent patients have the highest possible risk of root resorption due to the possible risk of cortical bone encroachment, while hypodivergent patients have the least possible risk. CLINICAL RELEVANCE: Analysis of apex-sinus distances can be of great help for safe posterior teeth intrusion and providing correct and adequate treatment.

Improving corrosion resistance and biocompatibility of AZ31 magnesium alloy by ultrasonic cold forging and micro-arc oxidation.

Corrosion resistant and biocompatible AZ31 magnesium alloy surfaces were successfully prepared by ultrasonic cold forging and subsequent micro-arc oxidation. The properties of these ultrasonic cold forging pretreated (UCFT)AZ31 magnesium alloy surfaces containing Sr-Ca-P micro-arc oxide coating (MAO/UCFT/AZ31) were studied. Results showed that surface grain refinement of AZ31 Mg alloy in the depth of 400 µm owing to the ultrasonic cold forging pretreatment was verified, and which provides more discharge channels for subsequent micro-arc oxidation. Comparing with the AZ31 magnesium alloy (AZ31) and ultrasonic cold forging technology treated AZ31 magnesium alloy samples (UCFT/AZ31), the corrosion resistance of MAO/UCFT/AZ31 significantly improved, which is also supported by the immersion experiments and electrochemical tests in simulated body fluid. Meanwhile, the MAO/UCFT/AZ31 samples also had excellent cytocompatibility as well as MAO/AZ31 samples. These results may beneficial to the developing of biodegradable medical materials in future.

Proximity of upper central incisors to incisive canal among subjects with maxillary dentoalveolar protrusion in various facial growth patterns.

OBJECTIVE: To investigate the position of the upper central incisor roots (U1) relative to the incisive canal (IC) among subjects with maxillary dentoalveolar protrusion in various facial growth patterns. MATERIALS AND METHODS: 240 cone beam computed tomography images of skeletal Class I and II maxillary or bimaxillary protrusive subjects with a mean age of 23.74 ± 3.73 years were enrolled according to their facial growth pattern. The IC volume was measured using Mimics 21 software (Materialise, Leuven, Belgium). The U1 inter-root distance, width of IC, and their proximity were estimated using Invivo6 software (Anatomage, San Jose, CA). RESULTS: The IC volume was slightly greater among the high angle facial group and female patients than the other groups. Overall, the IC width was greater than the U1 inter-root distance in 55.65%, 57.6%, and 65% among the average, low, and high angle facial groups, respectively, and in 56.5% and 62.9% of males and females, respectively. The overall anteroposterior (sagittal) distances between the U1 roots and IC were 4.36 ± 1.18, 4.78 ± 1.17, and 3.83 ± 0.90 mm among the average, low, and high angle facial groups, respectively. CONCLUSIONS: The high angle facial group and female patients showed slightly greater IC dimensions than the other groups. The overall maximum sagittal distances between the U1 and IC were around 5.5, 6, and 4.7 mm among the average, low, and high angle facial groups, respectively. The low angle facial group and male patients tended to have greater sagittal distances. Therefore, the present findings could serve as a guideline when a considerable amount of upper incisor retraction is planned for Class I or II maxillary or bimaxillary dentoalveolar protrusion patients.

Treatment of Dental Class-II, Division 2 Malocclusion Associated with a Deep Anterior Overbite: A Case Report Orthodontic Camouflage.

AIM: This study sought to correct the assessment of orthodontic camouflage treatment to provide a harmonized soft-tissue profile, consistent occlusion, and a pleasant smile. BACKGROUND: Class-II, division 2 malocclusions can be treated through dental compensation and growth modification methods instead of surgical-orthodontic treatment, which can be determined by the growth and age of the patient. CASE DESCRIPTION: This case report was of a 14-year-old Chinese female whose chief complaint was crowding of anterior teeth and required treatment for the same. On necessary clinical and radiographical examination, diagnosis of convex facial profile with class-II, division 2 malocclusion was arrived and hence treated with orthodontic camouflage. On treatment completion of 33 months, cephalometric assessment revealed that the anterior maxillary teeth had been successfully intruded and substantially distalized, with a slight counterclockwise rotation of the mandible. The treatment results and profile changes were demonstrated with good patient cooperation. CONCLUSION: Using a utility arch with orthodontic camouflage treatment can help to reinforce molar anchoring and improve a deep bite in the maxillary dentitions. The patient was treated with the devised treatment plan and acceptable results were obtained with patient satisfaction as recorded after 1 year of follow-up. CLINICAL SIGNIFICANCE: To correct a maxillomandibular discrepancy, an orthodontist may conduct a process known as camouflage therapy without necessity of surgery. However, patient selection forms a crucial role, and hence systematic arrival of the diagnosis and treatment protocol is a pivotal factor.

Study on the inhibition and remineralization of enamel demineralization by polydopamine in vitro / 口腔疾病防治

Objective@#To investigate the inhibitory effect of polydopamine (PDA) on enamel demineralization in isolated teeth and the induction of hydroxyapatite (HA) production on the surface of demineralized enamel to provide a novel protocol for the prevention and treatment of enamel demineralization. @*Methods@#Twenty isolated bovine teeth were cut into 20 enamel slices and randomly divided into an experimental group and a control group, with 10 slices in each group. The enamel slices in the experimental group were immersed in 2 mg/mL freshly prepared dopamine solution and incubated for 24 hours at room temperature in the dark to prepare the PDA coating, while the control group was left untreated. Then, the isolated bovine teeth, with and without PDA coating, were immersed in artificial demineralization solution at 37 °C for 3 days, followed by 7 days in simulated body fluid (SBF), and the immersion solution was changed daily. The surface morphology of enamel was observed by scanning electron microscopy (SEM), the calcium/phosphorus ratio of the enamel surface was analyzed by energy dispersive spectroscopy (EDS), and the characteristic functional groups in enamel deposits were analyzed by Fourier transform infrared spectroscopy (FTIR).@* Results@#Compared with the control group, the number of demineralized pores produced after 3 d of enamel demineralization with polydopamine coating was less, and the diameter was smaller. EDS elemental analysis showed that the Ca/P ratio after enamel demineralization was 2.37 in the experimental group, which was smaller than the 2.53 ratio in the control group. In the remineralization experiment, after 7 days of remineralization of PDA coated enamel in the experimental group, lamellar grains were produced on the enamel surface, and the growth showed obvious directionality, growth regularity and uniform arrangement. In the control group, the surface of enamel was flocculent mineral deposit, and the crystallinity was poor. The FTIR results proved that the enamel surface deposit of PDA-coated enamel was HA after 7 d of remineralization. @*Conclusion @#PDA can affect the nucleation process of HA and promote the production of HA on the surface of demineralized enamel.

Preparation and Characterization of Hydroxyapatite Coating on AZ31 Magnesium Alloy Induced by Carboxymethyl Cellulose-Dopamine.

Magnesium and its alloys have become potential implant materials in the future because of light weight, mechanical properties similar to natural bone, good biocompatibility, and degradability in physiological environment. However, due to the rapid corrosion and degradation of magnesium alloys in vivo, especially in the environment containing chloride ions, the application of magnesium alloys as implant materials has been limited. Therefore, improving the corrosion resistance of magnesium alloy and ensuring good biocompatibility is the main focus of the current research. In this study, hydroxyapatite coating was prepared on magnesium alloy surface using carboxymethyl cellulose-dopamine hydrogel as inducer to improve corrosion resistance and biocompatibility. Surface characterization techniques (scanning electron microscopy, Fourier-transformed infrared spectroscopy, energy dispersive X-ray spectroscopy- and X-ray diffraction) confirmed the formation of hydroxyapatite on the surface of AZ31 alloy. Corrosion resistance tests have proved the protective effect of Carboxymethyl cellulose-Dopamine/hydroxyapatite (CMC-DA/HA) coating on the surface of AZ31 alloy. According to MC3T3-E1 cell viability and Live/Dead staining, the coating also showed good biocompatibility. The results will provide new ideas for the biological application of magnesium alloys.

[Effect of orthodontic traction on the microstructure of dental enamel].

OBJECTIVE: To investigate the effect of orthodontic traction on the microstructure of dental enamel. METHODS: Forty-eight isolated premolars were randomly divided into 6 groups (n=8), including Group A (blank control group), in which the teeth were bonded with the orthodontic brackets without any loading force; Groups B1, B2, and B3 where the teeth were bonded with the orthodontic brackets using clinical adhesives and loaded with 50 g force for 6 months, 200 g force for 6 months, and 200 g force for 1 month, respectively; and Groups C1 and C2, where the teeth were bonded with straight wire brackets using light curing bonding and chemical curing bonding techniques, respectively. All the teeth were embedded with non-decalcified epoxy resin. Scanning electron microscope (SEM), atomic force microscope (AFM), and energy spectrometer (EDS) were used to analyze interface morphology and elemental composition of the teeth sliced with a hard tissue microtome. RESULTS: Compared with those in Group A, the teeth in the other 5 groups showed increased adhesive residue index with microcracks and void structures on the enamel surface under SEM; AFM revealed microcracks on the enamel surface with angles to the grinding direction. A larger loading force on the bracket resulted in more microcracks on the enamel interface. The interface roughness differed significantly between Groups A and C2, and the peak-to-valley distance differed significantly between Groups A, C, and C2. CONCLUSIONS: Orthodontic traction can cause changes in the microstructure of normal dental enamel.

Influence of Cu2+ Ions on the Corrosion Resistance of AZ31 Magnesium Alloy with Microarc Oxidation.

The objectives of this study were to reduce the corrosion rate and increase the cytocompatibility of AZ31 Mg alloy. Two coatings were considered. One coating contained MgO (MAO/AZ31). The other coating contained Cu2+ (Cu/MAO/AZ31), and it was produced on the AZ31 Mg alloy via microarc oxidation (MAO). Coating characterization was conducted using a set of methods, including scanning electron microscopy, energy-dispersive spectrometry, X-ray photoelectron spectroscopy, and X-ray diffraction. Corrosion properties were investigated through an electrochemical test, and a H2 evolution measurement. The AZ31 Mg alloy with the Cu2+-containing coating showed an improved and more stable corrosion resistance compared with the MgO-containing coating and AZ31 Mg alloy specimen. Cell morphology observation and cytotoxicity test via Cell Counting Kit-8 assay showed that the Cu2+-containing coating enhanced the proliferation of L-929 cells and did not induce a toxic effect, thus resulting in excellent cytocompatibility and biological activity. In summary, adding Cu ions to MAO coating improved the corrosion resistance and cytocompatibility of the coating.

Synergistic effects of titanium dioxide and cellulose on the properties of glassionomer cement.

In this study, we evaluate the effect of co-doping with TiO2 nanoparticles and sisal cellulose nanocrystals (CNCs) on the physical and biological properties of a conventional glass-ionomer cement (GIC). Test samples were characterized by scanning electron microscopy, and Fourier-transform infrared spectroscopy, and subjected to mechanical tests to evaluate the mechanical performances. Antimicrobial activity was evaluated against Candida albicans, and cytotoxicity experiments were conducted using L-929 cells. Unmodified GIC served as a control. Compared with the control group, the co-doped group demonstrated an increased compressive strength of 18.9%, an increased shear bond strength of 51%, the dissolution decreased by 18.3%, the volume wear rate was reduced by 5%. The antifungal effect against C. albicans was increased by 22%. In cytotoxicity experiments, the co-doped group had a slightly negative effect on the viability of L-929 cells.

RGDC Peptide-Induced Biomimetic Calcium Phosphate Coating Formed on AZ31 Magnesium Alloy.

Magnesium alloys as biodegradable metal implants have received a lot of interest in biomedical applications. However, magnesium alloys have extremely high corrosion rates a in physiological environment, which have limited their application in the orthopedic field. In this study, calcium phosphate compounds (Ca-P) coating was prepared by arginine-glycine-aspartic acid-cysteine (RGDC) peptide-induced mineralization in 1.5 simulated body fluid (SBF) to improve the corrosion resistance and biocompatibility of the AZ31 magnesium alloys. The adhesion of Ca-P coating to the AZ31 substrates was evaluated by a scratch test. Corrosion resistance and cytocompatibility of the Ca-P coating were investigated. The results showed that the RGDC could effectively promote the nucleation and crystallization of the Ca-P coating and the Ca-P coating had poor adhesion to the AZ31 substrates. The corrosion resistance and biocompatibility of the biomimetic Ca-P coating Mg alloys were greatly improved compared with that of the uncoated sample.

Preparation and antimicrobial assay of ceramic brackets coated with TiO2 thin films.

OBJECTIVE: Different methods have been utilized to prevent enamel demineralization and other complications during orthodontic treatment. However, none of these methods can offer long-lasting and effective prevention of orthodontic complications or interventions after complications occur. Considering the photocatalytic effect of TiO2 on organic compounds, we hoped to synthesize a novel bracket with a TiO2 thin film to develop a photocatalytic antimicrobial effect. METHODS: The sol-gel dip coating method was used to prepare TiO2 thin films on ceramic bracket surfaces. Twenty groups of samples were composed according to the experimental parameters. Crystalline structure and surface morphology were characterized by X-ray diffraction and scanning electron microscopy, respectively; film thickness was examined with a surface ellipsometer. The photocatalytic properties under ultraviolet (UV) light irradiation were analyzed by evaluating the degradation ratio of methylene blue (MB) at a certain time. Antibacterial activities of selected thin films were also tested against Lactobacillus acidophilus and Candida albicans. RESULTS: Films with 5 coating layers annealed at 700℃ showed the greatest photocatalytic activity in terms of MB decomposition under UV light irradiation. TiO2 thin films with 5 coating layers annealed at 700℃ exhibited the greatest antimicrobial activity under UV-A light irradiation. CONCLUSIONS: These results provide promising guidance in prevention of demineralization by increasing antimicrobial activities of film coated brackets.

Preparation of an orthodontic bracket coated with an nitrogen-doped TiO(2-x)N(y) thin film and examination of its antimicrobial performance.

A bracket coated with a nitrogen-doped (N-doped) TiO(2-x)N(y) thin film was prepared using the RF magnetron sputtering method. The physicochemical properties of the thin film were measured using X-ray diffraction and energy-dispersive X-ray spectrometry, while the antimicrobial activity of the bracket against common oral pathogenic microbes was assessed on the basis of colony counts. The rate of antimicrobial activity of the bracket coated with nano-TiO(2-x)N(y) thin film against Streptococcus mutans, Lactobacillus acidophilus, Actinomyces viscous, and Candida albicans was 95.19%, 91.00%, 69.44%, and 98.86%, respectively. Scanning electron microscopy showed that fewer microbes adhered to the surface of this newly designed bracket than to the surface of the normal edgewise bracket. The brackets coated with the N-doped TiO(2-x)N(y) thin film showed high antimicrobial and bacterial adhesive properties against normal oral pathogenic bacterial through visible light, which is effective in prevention of enamel demineralization and gingivitis in orthodontic patients.

[Preparation and antibacterial properties of nano-TiO(2-x)N(x) film].

OBJECTIVE: To prepare a nano-TiO2 film and characterize its antibacterial properties for dental application. METHODS: The TiO(2-x)N(x) antibacterial film was prepared by radio frequency (RF) magnetron sputtering. The crystal structure and surface morphology of the film were characterized by X-ray diffraction, scanning electron microscopy, and EDS, and the antibacterial properties of the film against common dental pathogenic bacteria were evaluated. RESULTS: The TiO(2-x)N(x) antibacterial film presented with an anatase phase with a mass ratio of nitrogen of 0.13% and compact and smooth surface. Antibacterial assay of the film showed a resistance rate of 97.79% against Streptococcus mutans, 49.42% against Actinomyces viscosus, and 96.84% against Candida albicans. CONCLUSION: The nano-TiO(2-x)N(x) film shows strong antibacterial effects against common dental pathogenic bacteria and can be used as a novel antibacterial dental material.