BACKGROUND AND OBJECTIVE

Orthodontic brackets predispose dental biofilm accumulation causing caries and gingivitis. Chlorhexidine is an adjunct to mechanical plaque removal, but has side-effects (tooth staining, bacterial resistance) due to long term use. This study tested the efficacy of Photodynamic Therapy, which produces reactive oxygen species, to reduce Streptococcus mutans in dental biofilm on orthodontic brackets.

A 5-day S. mutans biofilm was grown on forty enamel-bracket specimens. Thirty-nine specimens were randomized to three treatment groups: A. Distilled Water; B. 0.12% Chlorhexidine (CHX); C. Photodynamic Therapy (PDT) using Toluidine Blue O (TBO) as a photosensitizer, activated by red LED (630nm). After treatment, one random specimen from each group was viewed under Environmental Scanning Electron Microscopy (ESEM); the other 12 specimens, biofilms were collected, weighed, and cultured onto BHI agar plates to determine the number of CFU/mg. For baseline evaluation, one clean and one untreated specimens were preserved for ESEM.

Based on Tukey HSD test, group A had the most S. mutans (37.0573 CFU/mg) and was significantly different (pCONCLUSION

Both Photodynamic Therapy and 0.12% Chlorhexidine showed a significant reduction of S. mutans in dental biofilm on orthodontic brackets. However, there is no significant difference between them in reducing S. mutans CFU/mg. Photodynamic therapy could be an alternative adjunctive tool to mechanical removal of plaque adhered to orthodontic brackets.

Background and Objective: According to microbiological investigations, microorganisms, especially Lactobacillus strains, considerably increase after using fixed orthodontic appliances. One of the Lactobacilli bacteria found in the oral cavity is Lactobacillus acidophilus. The purpose of this study was to compare the adhesion of Lactobacillus acidophilus to metal and ceramic brackets with coated and uncoated nickel titanium (NiTi) orthodontic archwires. Methods: Forty () samples were divided into four groups for this in vitro study: 10 metal brackets with coated NiTi archwire, 10 metal brackets with uncoated NiTi archwire, 10 ceramic brackets with coated NiTi archwire, and 10 ceramic brackets with uncoated NiTi archwire. Elisa Reader was used to count the number of Lactobacillus acidophilus attachments, and the one-way ANOVA and Tukey HSD tests were used to analyze all results. Results: The results showed significant differences in the attachment of Lactobacillus Acidophilus between the ceramic bracket and coated NiTi archwire sample groups and the metal bracket and uncoated NiTi archwire sample groups (P= 0.01). The adherence of Lactobacillus acidophilus to the ceramic bracket and uncoated NiTi archwire group was higher than the metal bracket and coated NiTi archwire group, and the metal bracket and uncoated NiTi archwire group. The attachment of Lactobacillus acidophilus to the metal bracket and uncoated NiTi archwire groups was the lowest of all sample groups in this study. Conclusion The highest Lactobacillus acidophilus adherence was in the ceramic bracket with coated NiTi archwire group compared to the other three groups.
Lactobacillus acidophilus ; Orthodontic Brackets ; Orthodontic Wires

OBJECTIVES: This study aimed to construct the finite element model of the mandibular first molar with the invisible appliance and explore the dentition movement characteristics of the mandibular first molar when using micro-implant anchorage and different initial positions of the first molar. METHODS: Models of the mandible, tooth, periodontal membrane, and invisible appliance were constructed using cone beam computed tomography (CBCT) data. The two groups were divided into the non-anchorage group and the micro-implant group (between the roots of the first molar and the second molar) based on whether the elastic traction of the micro-implant was assisted or not. The two groups were divided into the following conditions based on the starting position of the first molar: Working condition 1: the distance between the first molar and the second premolar was 0 mm; working condition 2: the distance between the first molar and the second premolar was 1 mm; working condition 3: the distance between the first molar and the second premolar was 2 mm; working condition 4: the distance between the first molar and the second premolar was 3 mm. The data characte-ristics of total displacement and displacement in each direction of dentition were analyzed. RESULTS: In the non-ancho-rage group, all the other teeth showed reverse movement except for the first molar which was moved distally. Meanwhile, in the micro-implant group, except for a small amount of mesial movement of the second molar in wor-king condition 1, the whole dentition in other working conditions presented distal movement and anterior teeth showed lingual movement, among which the distal displacement of the first molar in working condition 4 was the largest. With the change of the initial position of the first molar to the distal, the movement of the first molar to the distal, the premolar to the mesial, and the anterior to the lip increased, while the movement of the second molar to the mesial decreased. CONCLUSIONS The micro-implant can effectively protect the anterior anchorage, increase the expression rate of molar distancing, and avoid the round-trip movement of the second molar. The initial position of the first molar movement is related to the amount of distancing and the remaining tooth movement.
Finite Element Analysis ; Molar ; Bicuspid ; Periodontal Ligament ; Tooth Movement Techniques/methods* ; Orthodontic Appliances, Removable

OBJECTIVES: To evaluate the effects of a Twin-block appliance on the condyles of patients with ClassⅡmalocclusion by conducting a systematic review and a Meta-analysis. METHODS: Pubmed, Embase, Cochrane Library, Chinese BioMedical Literature Database, China National Knowledge Infrastructure, and VIP Database were electronically searched. Randomized controlled trials, controlled clinical trials, and single-arm trials on condylar changes produced by a Twin-block appliance in patients with ClassⅡmalocclusion were included. Two reviewers independently extracted and assessed the risk of bias. Meta-analyses were conducted with Review Manager 5.3. RESULTS: Eight studies were included; among which, seven were of high quality. After treatment with a twin block appliance, condyles moved anteriorly. The anterior joint spaces decreased (P<0.000 01), whereas the posterior spaces increased (P<0.000 01). The superior spaces were not changed (P=0.11). Moreover, a significant difference was observed in the increase of the condylar space index (P<0.000 01). After treatment, the anteroposterior diameters of the condyles and condylar height increased (P=0.000 2 and P<0.000 01, respectively). By contrast, no significant changes were discovered in the medial external diameters of the condyles (P=0.42). CONCLUSIONS A Twin-block appliance can promote the growth of a condyle in the posterior and upper direction and move it forward in favor of the correction of Class Ⅱ malocclusion.
Humans ; Malocclusion, Angle Class II/therapy* ; Temporomandibular Joint ; Bone and Bones ; China ; Orthodontic Appliances, Functional ; Cephalometry

OBJECTIVES: This study aimed to conduct a meta-analysis of the efficacy of mandibular advance clear alig-ners with traditional functional appliances as the control group. METHODS: PubMed, Web of Science, Embase, Cochrane Library, China Biomedical Abstracts Database, China Knowledge Network Database, Wanfang Database, and Weipu Database were used in this study. The two groups of researchers screened the literature and extracted data based on the inclusion and exclusion criteria established by PICOS entries, and used the ROBINS-I scale for quality evaluation. Revman 5.4 and Stata 17.0 software were used for meta-analysis. RESULTS: Nine clinical controlled trials were included in this study with a total sample size of 283 cases. No significant difference was found in SNA, SNB, ANB, Go-Pog, U1-SN, Overjet, and other aspects between the invisible group and the traditional group in the treatment of skeletal class Ⅱ ma-locclusion patients; there was a 0.90° difference in mandibular plane angle between the two groups; the growth of the mandibular ramus (Co-Go) in the traditional group was 1.10 mm more than that in the invisible group; the lip inclination of the lower teeth in the invisible group was better controlled, 1.94° less than that in the control group. CONCLUSIONS The invisible group can better control the lip inclination of the mandibular anterior teeth when guiding the mandible. Furthermore, the mandibular plane angle (MP-SN) can remain unchanged, but the growth of the mandibular ramus is not as good as the traditional group, and auxiliary measures should be taken to improve it in clinical practice.
Humans ; Malocclusion, Angle Class II/therapy* ; Mandibular Advancement ; Orthodontics, Corrective ; Orthodontic Appliances, Functional ; Mandible ; Orthodontic Appliances, Removable ; Cephalometry

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.
Humans ; Periodontal Ligament/physiology* ; Orthodontic Wires ; Cheek ; Ulcer ; Tooth ; Finite Element Analysis

ABSTRACT Duration of orthodontic treatment becomes major concern. The present study compared shear bond strength (SBS) and adhesive remnant index (ARI) values of different adhesive systems with different application methods on rebonding process of retrieved orthodontic brackets. Eighty premolar teeth were equally divided into five groups. Transbond XT (TXT) which belongs to total-etch system was used in Group 1 as the control group. Nova Compo-SF (NC) and Vertise Flow (VF) (Kerr Dental, Italy) which are self-adhering flowable composites were used in Group 2 (NC+etch) and Group 3 (VF+etch) respectively with additional etching before application. Group 4 (NC) and Group 5 (VF) were used by following instructions of each brand. The brackets were debonded with a bracket removing plier and rebonded with the same procedures after sandblasting of the bracket and surface cleaning of the enamel. SBS and ARI were measured for each sample. Comparison between all groups was performed by Kruskal-Wallis test and chisquare test. The highest SBS was observed in NC+etch (median = 11.44, mean = 13.49±9.42), followed by NC (median = 10.17, mean = 11.35±6.55), TXT (median = 6.36, mean = 8.06±6.33), VF+etch (median = 5.68, mean = 6.75±4.58), and VF (median = 2.62, mean = 2.92±2.57), respectively. ARI 1 was observed in 81.3% of TXT whereas 62.5% of NC+etch. ARI 1, 2, and 3 were equally distributed in VF+etch group (31.3%). ARI 5 was observed in 37.5% of NC and 62.5% of VF. Analyses referred to statistically significant differences between five groups regarding both SBS and ARI (p < 0.001). As NC showed the highest SBS on rebonding process, it can be a promising alternative to TXT which is the gold standard.
Dental Materials ; Orthodontic Brackets

OBJECTIVES: This study aimed to investigate the accuracy of model superimposition and automatic analysis for upper and lower dentition widths in iTero Progress Assessment during the clear aligner process. METHODS: Nineteen cases were included in this retrospective case control study. Pretreatment dental cast (T0) and post treatment dental cast after staged treatment (T1) were available for three-dimensional (3D) model superimposition. The movements of maxillary teeth in the horizontal plane (cross section) after staged treatment and the widths of upper and lower dentitions were measured by 3D model superimposition in real world and iTero Progress Assessment. The data collected from the two methods were compared. RESULTS: The movements [Median (upper and lower quartiles)] of maxillary teeth in the horizontal plane after staged treatment were 2.31 (1.59, 3.22) and 1.79 (1.21, 3.03) mm in iTero Progress Assessment and 3D model analysis, respectively. Significant difference was observed between the two groups (P<0.05). In the measurement of upper and lower dentition width, four indicators were measured, including intercanine width upper, intermolar width upper, intercanine width lower, and intermolar width lower. Before treatment, the measurement of iTero Progress Assessment were (35.78±2.49), (56.21±2.51), (27.43±1.38), (52.26±2.91) mm, respectively, and actual measurement were (35.77±2.53), (56.17±2.47), (27.40±1.41), (52.30±2.86) mm, respectively, without significant difference (P>0.05). After stage treatment, the measurement of iTero Progress Assessment were (37.37±2.86), (57.76±2.56), (28.89±2.00), (54.16±2.19) mm, respectively, and actual measurement were (37.29±2.94), (57.71±2.63), (28.88±2.05), (54.01±2.15) mm, respectively, and there was no significant difference (P>0.05). CONCLUSIONS The data from iTero Progress Assessment did not coincide with the model superimposition results with palate as reference. The accuracy of model superimposition in iTero Progress Assessment needs further investigation, whereas the arch width analysis is accurate. Therefore, iTero Progress Assessment results should be interpreted with caution by orthodontists in clinical applications.
Case-Control Studies ; Cuspid ; Dental Arch ; Orthodontic Appliances, Removable ; Retrospective Studies ; Humans

In recent years, the early orthodontic treatment of malocclusion has become a hot issue in the field of orthodontics. Some new phenomena and new problems that have emerged require in-depth analysis and discussion, and need to be given correct guidance and norms. Malocclusion refers to the deformities of teeth, jaws, and craniofacial bones caused by genetic and environmental factors during growth and development. Based on the accurate judgment of the etiology and diagnosis, choosing the right time and suitable indications, with the advantage of growth and development, the most suitable appliance can be selected in the early stage of malocclusion to fix malocclusion, and to effectively prevent and block the formation and development of malocclusion. This article will discuss how to timely and appropriately carry out the early prevention and treatment of malocclusion with six aspects, including methods of performing early orthodontic treatment, the basis and guarantee of early orthodontic treatment, correctly understanding early orthodontic treatment, the issues that should be paid attention to in carrying out early orthodontic treatment, actively advocating multidisciplinary cooperation during early orthodontic treatment and understanding face management in a serious way.
Dental Care ; Humans ; Malocclusion/therapy* ; Malocclusion, Angle Class II/therapy* ; Orthodontic Appliances, Functional ; Orthodontics, Corrective/methods*

Early orthodontic treatment refers to the orthodontic treatment of dental-maxillofacial deformities in the early deciduous or mixed dentition. More and more attentions has been paid to early orthodontic treatment. Many kinds of orthodontic appliances are emerging on the market with the rapid development of the orthodontic technology. At the same time, problems and increased risks have followed in early orthodontic treatment. The contents of the article include the establishment of deciduous occlusion and the characteristics of the deciduous dentition, the orthodontic principles of different stages of deciduous dentition, the oral bad habits during the deciduous dentition and the risk control of early orthodontic treatment.
Dental Occlusion ; Dentition, Mixed ; Humans ; Malocclusion/therapy* ; Orthodontic Appliances ; Tooth, Deciduous