Clinical analysis of successful insertion of orthodontic mini-implants in infrazygomatic crest.

BACKGROUND: The insertion positions of mini-implant in infrazygomatic crest has been reported, but due to the anatomical variation, the precise location of this site is not clear yet. This study used cone-beam computed tomography (CBCT) to analyze the position and angle of mini-implants successfully inserted in the infrazygomatic crest, with the goal of providing reference data for clinical practice. METHODS: CBCT was used to image 40 mini-implants and their surrounding tissues in adult orthodontic patients who successfully underwent mini-implant insertion in the infrazygomatic crest. The insertion positions and angles of mini-implants were measured, and the thicknesses of buccal and palatal bone adjacent to the mini-implants were also recorded. Then, we proposed the position and implantation angle for infrazygomatic crest insertion. According to the position and angle, the cortical bone thickness and distance to the root of another 54 randomly selected infrazygomatic crests were recorded to verify its feasibility. RESULTS: In the coordinate system, the implantation position of the 40 successful mini-implants was (-0.4 ± 2, 8.2 ± 2.5) and the implantation angle between the long axis of the mini-implant and horizontal reference plane was 56.4° ± 7.7°. The bone thicknesses on buccal and palatal sides of infrazygomatic crest adjacent to mini-implants were 4.1 ± 2.5 mm and 7.2 ± 3.2 mm, respectively, and the cortical bone thickness was 2.4 ± 0.6 mm. Among 54 infrazygomatic crests, 75.9% of them met the safety and stability requirements. When the implantation height was increased by 1, 2, and 3 mm, the proportions of implants that met requirements for success were 81.5%, 90.7%, and 94.4%, respectively. But, the proportions of eligible implants were limited at implantation angle increases of 5° and 10°. CONCLUSIONS: Using the long axis of the maxillary first permanent molar (U6) as the vertical reference line, mini-implants could be safely inserted in the infrazygomatic crest at a distal distance of 0.4 mm and height of 8.2 mm from the central cementum-enamel junction of U6, with an implantation angle of 56.4°. The success rate increased when the implant height increased, but the proportion of eligible implantation was limited with the increase of implantation angle.

Feasibility of mini-implant insertion between mesial and distal buccal roots of a maxillary first molar: A cone-beam computed tomography imaging study.

INTRODUCTION: Mini-implant insertion in the maxillary posterior region can be influenced by anatomic limitations, thus increasing the failure rate. We explored the feasibility of a new implantation site: the region between the mesial and distal buccal roots of the maxillary first molar. METHODS: Cone-beam computed tomography data from 177 patients were collected from a database. The maxillary first molars were morphologically classified by analyzing the angle and morphology of the mesial and distal buccal roots. Next, 77 subjects were randomly selected from the 177 patients to measure and analyze the hard-tissue morphology in the maxillary posterior region. RESULTS: We devised the Morphological Classification on the Mesial and Distal Buccal Roots of Maxillary First Molar (MCBRMM), divided into 3 types: MCBRMM-I, II, and III. In all subjects, MCBRMM-I, II, and III accounted for 43%, 25%, and 32%, respectively. At 8 mm from the mesial cementoenamel junction of maxillary first molars, the interradicular distance between the maxillary first molar's mesiodistal buccal roots of MCBRMM-I was 2.6 mm, showing an upward trend from the cementoenamel junction to the apex. The distance from the buccal bone cortex to the palatal root was >9 mm. The buccal cortical thickness was >1 mm. CONCLUSIONS: This study provided a potential site for mini-implant insertion in the maxillary posterior region: the alveolar bone of maxillary first molars in MCBRMM-I.

Investigation of periodontal status and bacterial composition aroundmini-implants.

INTRODUCTION: Mini-implants are now widely used in orthodontic treatment. Soft-tissue inflammation around the mini-implant is an important factor affecting its stability. This study aimed to investigate the periodontal status and the bacterial composition around mini-implants. METHODS: A total of 79 mini-implants in 40 patients (aged 18-45 years) were evaluated in this study. The mini-implant probing depth (mPD), mini-implant gingival sulcus bleeding index (mBI), mini-implant plaque index (mPLI), and the composition of the supragingival and subgingival plaque around the mini-implants were recorded. After Congo red staining, the bacteria were classified and counted under a light microscope. RESULTS: The mPLI and mBI around mini-implants in the infrazygomatic crest were higher than those in the buccal shelf and interradicular area. The mPD was higher on the coronal site of the mini-implant than on the mesial, distal, and apical sites in the infrazygomatic crest. The mPLI around the mini-implant was positively correlated with the mBI, and the mBI was positively correlated with the mPD. The supragingival and subgingival bacterial composition around the mini-implants was similar to that of natural teeth. Compared with supragingival bacterial composition, the subgingival bacteria of mini-implants had a significantly lower proportion of cocci and a higher proportion of bacilli and spirochetes. CONCLUSIONS: The bacteria composition of the plaque and the location are important factors in the inflammation around mini-implants. Similar to natural teeth, mini-implants require health maintenance to prevent inflammation of the surrounding soft tissue and maintain stability.

Temporomandibular Joint Osseous Morphology of Class I and Class II Malocclusions in the Normal Skeletal Pattern: A Cone-Beam Computed Tomography Study.

(1) Background-The aim of the present study was to evaluate the correlation between the temporomandibular joint (TMJ) osseous morphology of normal skeletal pattern individuals with different dental malocclusions by using cone-beam computed tomography (CBCT). (2) Methods-The CBCT images of bilateral TMJs in 67 subjects with skeletal class I and average mandibular angle (26 males and 41 females, age range 20-49 years) were evaluated in this study. The subjects were divided into class I, class II division 1, and class II division 2 according to the molar relationship and retroclination of the maxillary incisors. Angular and linear measurements of TMJ were evaluated and the differences between the groups were statistically analyzed. (3) Results-Intragroup comparisons showed statistical differences for articular eminence inclination, the width of the glenoid fossa, the ratio of the width of the glenoid fossa to the depth of the glenoid fossa, the condylar angle, and the intercondylar angle between the malocclusion groups. The measurements of the glenoid fossa shape showed no significant difference between the left and right sides. Females showed more differences in the morphological parameters of TMJ between the three malocclusion groups than the males. (4) Conclusion-The present study revealed differences in the TMJ osseous morphology between dental class I and class II malocclusions in the normal skeletal pattern.

Is There an Association between Temporomandibular Disorders and Articular Eminence Inclination? A Systematic Review.

(1) Background: In order to determine the correlation between the inclination of articular eminence (AEI) and the development of temporomandibular disorders (TMDs), a systematic review was performed. (2) Methods: A systematic literature research was conducted between 1946 and January 2020, based on the following electronic databases: PubMed, Cochrane Library, Embase, Medline, Scope, SciELO, and Lilacs. Observational studies, analytical case-control studies, and cohort studies written in English were identified. The articles were selected and analyzed by two authors independently. The PICO format was used to analyze the studies and the Newcastle-Ottawa Scale (NOS) was used to verify the quality of the evidence. (3) Results: Sixteen articles were included in this review, ten case-control studies and six cohort studies. Eight articles (50%) established a positive relation between AEI and TMDs and eight (50%) did not. The scientific quality was medium-low, mainly influenced by the exposure to the risk of bias and the lack of clinical methods with adequate consistency and sensitivity on the diagnosis of TMDs. (4) Conclusions: It is controversial to establish a causal relationship between the TMDs and the AEI in the field of stomatology, due to limited and inconclusive evidence. However, it is suggested that the AEI defined by some specific methods may be associated with some special pathological stages of TMDs. High-quality prospective studies are required to draw any definitive conclusions.

Bonding Strength of Orthodontic Brackets on Porcelain Surfaces Etched by Er:YAG Laser.

OBJECTIVE: To evaluate the effect of erbium: yttrium aluminium garnet laser conditioning bond strength of orthodontic brackets on porcelain surfaces. BACKGROUND: There are few studies that evaluate the effect of Er:YAG laser about orthodontic bonding on porcelain surface. The efficacy of Er:YAG laser in porcelain conditioning is controversial. MATERIALS AND METHODS: Ninety ceramic specimens were randomly divided into five group, group A: etched with hydrofluoric (HF) acid; group B and C: etched with an energy parameter of 250 mJ, 20 Hz and 300 mJ, 20 Hz by Er:YAG laser instrument; group D and E: etched with an energy parameter of 250 mJ, 20 Hz and 300 mJ, 20 Hz of Er:YAG laser with HF etching. Afterward, two samples selected randomly from each group were evaluated by scanning electron microscopy. Brackets were bonded on the remaining samples, which were stored in distilled water and thermocycled. Each group was measured by shear bond strength (SBS), tensile bond strength (TBS), porcelain fracture index (PFI), and adhesive remnant index (ARI) calculation. Data were statistically analyzed using SPSS software. RESULTS: The SBS and TBS in group E were the largest. Comparing SBS and TBS of HF group and other Er:YAG laser group, there were statistically significant difference (p < 0.05). PFI was significantly higher in shear force group than the tensile force group. HF group had higher ARI score than the other groups. CONCLUSIONS: Porcelain surfaces etched by 250 mJ, 20 Hz of Er:YAG laser combined with HF acid can get enough bond strength and have lower porcelain fracture rate for orthodontic bracket bonding.

Structural and functional characterization of MBS301, an afucosylated bispecific anti-HER2 antibody.

MBS301, a glyco-engineered bispecific anti-human epidermal growth factor receptor 2 (HER2) antibody with a typical IgG1 monoclonal antibody structure, was developed through dual-cell expression and in vitro assembling process. MBS301 consists of two half antibodies engineered from trastuzumab and pertuzumab, respectively. Integrity and purity profiles of MB301 indicated that the heterodimerization of the two half antibodies was successful. The high and similar melting temperatures (Tm1,72.0°C and Tm2, 84.8°C) of MBS301 compared with those of its parental monoclonal antibodies trastuzumab and pertuzumab (in-house made T-mab and P-mab, respectively) revealed its structural compactness. With computer-modeling experiments and Biacore binding and competition kinetics studies, the binding stoichiometry between MBS301 and HER2-ECD was determined to be 1:1 and the two arms of MBS301 were shown to bind to domains II and IV of HER2-ECD antigen simultaneously. MBS301 displayed synergistic bioactivities as the combination of T-mab and P-mab in vitro in multiple cancer cell lines and in vivo in xenograft mouse model studies, and showed more effective activity than T-mab or P-mab used individually. Moreover, fucose-knockout dramatically increased MBS301's binding affinity to low affinity FcγRIIIa allotype 158F (KD = 2.35 × 10-7M) to near the high affinity level of allotype V158 (KD = 1.17 × 10-7M). This resulted in far more effective ADCC activity of MBS301 than the combination of T-mab and P-mab in killing HER2-positive cancer cells. Hence, a novel fully afucosylated anti-HER2 bispecific antibody with improved antitumor activities was generated and shown to have the potential to be used for treating HER2-positive but trastuzumab-resistant solid tumors.

A trehalose biosynthetic enzyme doubles as an osmotic stress sensor to regulate bacterial morphogenesis.

The dissacharide trehalose is an important intracellular osmoprotectant and the OtsA/B pathway is the principal pathway for trehalose biosynthesis in a wide range of bacterial species. Scaffolding proteins and other cytoskeletal elements play an essential role in morphogenetic processes in bacteria. Here we describe how OtsA, in addition to its role in trehalose biosynthesis, functions as an osmotic stress sensor to regulate cell morphology in Arthrobacter strain A3. In response to osmotic stress, this and other Arthrobacter species undergo a transition from bacillary to myceloid growth. An otsA null mutant exhibits constitutive myceloid growth. Osmotic stress leads to a depletion of trehalose-6-phosphate, the product of the OtsA enzyme, and experimental depletion of this metabolite also leads to constitutive myceloid growth independent of OtsA function. In vitro analyses indicate that OtsA can self-assemble into protein networks, promoted by trehalose-6-phosphate, a property that is not shared by the equivalent enzyme from E. coli, despite the latter's enzymatic activity when expressed in Arthrobacter. This, and the localization of the protein in non-stressed cells at the mid-cell and poles, indicates that OtsA from Arthrobacter likely functions as a cytoskeletal element regulating cell morphology. Recruiting a biosynthetic enzyme for this morphogenetic function represents an intriguing adaptation in bacteria that can survive in extreme environments.

Effects of various debonding and adhesive clearance methods on enamel surface: an in vitro study.

BACKGROUND: The purpose of this study was to evaluate orthodontic debonding methods by comparing the surface roughness and enamel morphology of teeth after applying two different debonding methods and three different polishing techniques. METHODS: Forty eight human maxillary premolars, extracted for orthodontic reasons, were randomly divided into three groups. Brackets were bonded to teeth with RMGIC (Fuji Ortho LC, GC, Tokyo, Japan) (two groups, n = 18 each) after acid etching (30s), light cured for 40 s, exposed to thermocycling, then underwent 2 different bracket debonding methods: debonding pliers (Shinye, Hangzhou, China) or enamel chisel (Jinzhong, Shanghai, China); the third group (n = 12) comprised of untreated controls, with normal enamel surface roughness. In each debonded group, three cleanup techniques (n = 6 each) were tested, including (I) diamond bur (TC11EF, MANI, Tochigi, Japan) and One-Gloss (Midi, Shofu, Kyoto, Japan), (II) a Super-Snap disk (Shofu, Kyoto, Japan), and (III) One-Gloss polisher. The debonding methods were compared using the modified adhesive remnant index (ARI, 1-5). Cleanup efficiencies were assessed by recording operating times. Enamel surfaces were qualitatively and quantitatively evaluated with scanning electron microscopy (SEM) and surface roughness tester, respectively. Two surface roughness variables were evaluated: Ra (average roughness) and Rz (10-point height of irregularities). RESULTS: The ARI scores of debonded teeth were similar with debonding pliers and enamel chisel (Chi-square = 2.19, P > 0.05). There were significant differences between mean operating time in each group (F = 52.615, P < 0.01). The diamond bur + One-Gloss took the shortest operating time (37.92 ± 3.82 s), followed by the Super-Snap disk (56.67 ± 7.52 s), and the One-Gloss polisher (63.50 ± 6.99 s). SEM appearance provided by the One-Gloss polisher was the closest to the intact enamel surface, and surface roughness (Ra: 0.082 ± 0.046 µm; Rz: 0.499 ± 0.200 µm) was closest to the original enamel (Ra: 0.073 ± 0.048 µm; Rz: 0.438 ± 0.213 µm); the next best was the Super-Snap disk (Ra: 0.141 ± 0.073 µm; Rz: 1.156 ± 0.755 µm); then, the diamond bur + One-Gloss (Ra: 0.443 ± 0.172 µm; Rz: 2.202 ± 0.791 µm). CONCLUSIONS: Debonding pliers were safer than enamel chisels for removing brackets. Cleanup with One-Gloss polisher provided enamel surfaces closest to the intact enamel, but took more time, and Super-Snap disks provided acceptable enamel surfaces and efficiencies. The diamond bur was not suitable for removing adhesive remnant.

[Interleukin-17 expression induced by orthodontic force in periodontal ligament in different periodontal condition].

OBJECTIVE: To investigate interleukin (IL)-17 expression induced by orthodontic force in periodontal ligament under different periodontal conditions. METHODS: Seventy-seven male SD rats were divided randomly into 5 groups: healthy movement group (HM), active periodontitis movement group (PM) recovery periodontitis movement group (RM), positive control group (PC) and normal control group (NC). Active periodontitis was set up by means of ligature + susceptible bacteria + suger water in PM, PC and RM groups. This stimulating factor was removed in RM group. NiTi spring was used to apply 0.49 N mesial force to move upper first molar of the rats in HM, PM and RM groups. HM, PM and RM group rats were sacrificed on day 3 (d3), day 7 (d7) and day 14 (d14). Expression changes of IL-17 in periodontal tissue in each group were measured using immunohistochemical stain and real time fluorescence quantitative PCR. RESULTS: IL-17 expression in periodontal ligament showed more positively in PM and RM groups compared with NC, PC and HM groups. No difference was found in the expression of IL-17 mRNA in NC (1.00 ± 0.00) (P > 0.05), except in HM d14 (1.00 ± 0.07) and RM d14 (1.19 ± 0.15). Higher expression of IL-17 mRNA (P < 0.05) was found in other groups. The expression of IL-17 mRNA in RM d3 and d7 increased more than that in HM group in the same period (P < 0.05) and it decreased significantly (P < 0.05) compared with that in PM groups in the same period. CONCLUSIONS: IL-17 was involved in the regulation of orthodontic tooth movement in different periodontal conditions. Orthodontic force caused limited increase of IL-17 mRNA expression in recovery phase of periodontitis at early stage, then back to normal. However, in active inflammatory periodontal tissue, orthodontic force kept IL-17 mRNA at high level.