Orthodontic treatment of a patient with dentinogenesis imperfecta using a clear aligner system.

BACKGROUND: Orthodontic treatment for patients with dentinogenesis imperfecta (DGI) can be risky because of the fragility of their dental hard tissue. Although the Invisalign (Align Technology) clear aligner system should be a suitable orthodontic appliance for patients with DGI, to the authors' knowledge, there has been no related research. CASE DESCRIPTION: A 28-year-old woman with DGI sought treatment with a 1 mm open bite, edge-to-edge occlusion of the central incisors, and a bilateral Class III cusp-to-cusp molar relationship. Invisalign was applied for her treatment, and after 3 and one-half years of orthodontic therapy, a normal overjet and overbite were achieved, accompanied by retraction of the lower lip as well as a bilateral Class I molar relationship. In addition, there was no iatrogenic injury to the patient's teeth. PRACTICAL IMPLICATIONS: The Invisalign system may be a suitable orthodontic appliance for patients with DGI because clear aligners lessen the tensile stress to the teeth, decrease the number and area of bonds to the teeth, and offer protective effects through a full wrap of plastic that covers the crowns of the teeth.

The Cell Adhesion and Proliferation Enhancement Impact of Low-Temperature Atmospheric Pressure Plasma-Polymerized Heptylamine on the Surface of Ti6Al4V Alloy.

To chemically functionalize the Ti6Al4V alloy surface, a custom-made low-temperature atmospheric pressure plasma reactor device was used to polymerize heptylamine on it. The effect of different deposition times, an important process parameter, was also investigated. For each deposition time group, the surface morphology was observed via scanning electron microscopy (SEM). The surface chemical content was analyzed via X-ray photoelectron spectroscopy, and surface hydrophilicity was measured via water contact angle. The adhesion of bone marrow stromal cells (BMSCs) on the modified Ti6Al4V alloy surfaces was also observed via SEM. A quantitative evaluation of cell proliferation was performed via the Cell Counting Kit-8 assay. The results revealed that amino groups were introduced on the Ti6Al4V alloy surface via plasma-polymerized heptylamine (PPHA). The percentages of NH2/C for various deposition times (0 s, 30 s, 45 s, 60 s, 90 s, and 120 s) were 3.39%, 5.14%, 6.71%, 6.72%, 7.31%, and 7.65%. A 30 s, 45 s, and 60 s deposition time could significantly increase surface hydrophilicity with a mean water contact angle of 62.1 ± 1.6°, 65.7 ± 1.1°, and 88.2 ± 1.4°, respectively. Meanwhile, a 60 s, 90 s, and 120 s deposition time promoted BMSCs cell adhesion and proliferation. However, this promotion effect differed non-significantly among the three groups. In conclusion, the introduction of amino groups on the Ti6Al4V alloy surface exhibited surface modification and enhancement of cell adhesion and proliferation, which was partially associated with deposition time.

Direct observation of terahertz topological valley transport.

Topological photonics offers the possibility of robust transport and efficiency enhancement of information processing. Terahertz (THz) devices, such as waveguides and beam splitters, are prone to reflection loss owing to their sensitivity to defects and lack of robustness against sharp corners. Thus, it is a challenge to reduce backscattering loss at THz frequencies. In this work, we constructed THz photonic topological insulators and experimentally demonstrated robust, topologically protected valley transport in THz photonic crystals. The THz valley photonic crystal (VPC) was composed of metallic cylinders situated in a triangular lattice. By tuning the relevant location of metallic cylinders in the unit cell, mirror symmetry was broken, and the degenerated states were lifted at the K and K' valleys in the band structure. Consequently, a bandgap of THz VPC was opened, and a nontrivial band structure was created. Based on the calculated band structure, THz field distributions, and valley Berry curvature, we verified the topological phase transition in such type of THz photonic crystals. Further, we showed the emergence of valley-polarized topological edge states between the topologically distinct VPCs. The angle-resolved transmittance measurements identified the bulk bandgap in the band structure of the VPC. The measured time-domain spectra demonstrated the topological transport of valley edge states between distinct VPCs and their robustness against bending and defects. Furthermore, experiments conducted on a topological multi-channel intersectional device revealed the valley-polarized characteristic of the topological edge states. This work provides a unique approach to reduce backscattering loss at the THz regime. It also demonstrates potential high-efficiency THz functional devices such as topologically protected beam splitters, low-loss waveguides, and robust delay lines.

Assessment of dynamic smile and gingival contour in young Chinese people.

OBJECTIVES: This study aimed to classify the dynamic smile and to quantify the gingival line (GL), as well as apico-coronal displacement of the gingival zenith (GZ), in the maxillary anterior dentition in a young Chinese population. METHODS: Two-hundred young Chinese subjects (100 men and 100 women; 20-35 years of age) with healthy dentogingival tissue were recruited. The dynamic smile process was captured using a digital camera. The smile type, GL type, the vertical distance of the GZ between the canine and the central incisor on the same side and the GZ of the lateral incisor-GL relationship were measured using a self-developed smile-analysis method. The kappa statistics was used to examine the reliability of the data recorded by the rater. The Pearson chi-square test was used to analyse the differences between subjects regarding the frequencies of smile type and GL type at α = 0.05. RESULTS: Data revealed that 45.5% of subjects had a high smile and 45.5% had an average smile; 58.2% of the subjects presented an upwards GL. The GZ of canine teeth was 0.33 mm apical to the corresponding central incisor and no significant difference between both sides of the GZ was observed. The GZ of the lateral incisor was located coronal to the GL in 87.9% of samples. The vertical distance between the GZ of the lateral incisor and the GL was 0.59 mm and no statistically significant difference was detected. CONCLUSIONS: The most common findings were a high or average smile type, combined with an upward GL. In the majority of subjects, the GZ of the lateral incisor is coronal to the GL. The apico-coronal displacement of the GZ showed bilateral symmetry.

A novel technique for measurement of dentogingival tissue by cone beam computed tomography.

OBJECTIVES: To develop a novel technique to visualize dentogingival profiles by using cone beam computed tomography (CBCT) and to evaluate the accuracy of mucogingival tissue thickness measurements with CBCT, as compared with direct measurements in vitro. METHODS: A silicone matrix loaded with radiopaque impression material was prepared before performing CBCT on a patient. Two dry cadaver mandibles with simulated mucogingival tissue and six segmental cadaver jaws were used to assess the accuracy of mucogingival tissue thickness measurements directly and radiographically with CBCT images. Paired t tests were used to evaluate the intra- and interexaminer reliability and to compare the data between direct and CBCT imaging measurements at α = 0.05. RESULTS: No statistically significant differences were observed between direct and CBCT imaging measurements of simulated mucogingival tissue thickness in mandibular models and in cadaver jaws (P > .05). Results of direct measurements with simulated mucogingival tissue thickness indicated good intra- and interexaminer reliability. CONCLUSIONS: A novel technique was developed to obtain mucogingival tissue thickness data on the use of radiopaque impression materials and CBCT imaging. This new method provides a reliable visual dentogingival profile and a means to objective measurements.

[Combined crown lengthening surgery with restorative therapy for inducing papilla growth: a case report].

A young lady with unsatisfied restorations of upper anterior teeth and swollen gum wanted to improve aesthetics. Oral examination showed that 12-22 were provisional crowns with normal occlusion, poorly gingival contour and gummy smile. The gingiva was red, light swollen and bleeding on probing. X-ray showed the roots of 11, 21 were short and the alveolar bone absorbed. After the periodontal initial treatment, an ideal location of gingival margin was determined. Then, an esthetic periodontal surgery was performed to recover the biology width and the gingival margin was fitted with the anterior teeth. The temporary restorations were made twice to guide the gingiva growth by changing the shape of the restorations and moving up the contact points of the restorations. The ceramic crowns were completed 3 months after the operation. The gummy smile disappeared and the gingival margin was filled well with the upper anterior ceramic crowns. The 14-month follow-up presented a satisfied effect. Crown lengthening surgery combined restorative therapy could lead papilla to grow well. This process is beneficial for the future treatment plan and clinical esthetic evaluation.

[Shape analysis of healthy gingival curve in maxillary anterior teeth in 120 Chinese youth].

OBJECTIVE: To establish the relationship of the gingival crest, the gingival curve characteristic point (inflection point, IP) and the contact points and to use it as reference to design the location of contact area in anterior teeth restoration to form the natural papillae. METHODS: Two-dimensional gingival curve morphology analysis based on standardized digital images was done to measure the value of different points in the upper anterior teeth for 120 young Chinese. RESULTS: In the maxillary anterior teeth, the average mesial papilla heights(MPH) of central incisors(CI), lateral incisors(LI), canines(CA) were (4.49 ± 0.86) mm, (3.64 ± 0.77) mm and (4.12 ± 0.92) mm; the average distal gingival papilla heights(DPH) were (4.09 ± 0.72) mm, (3.48 ± 0.83) mm and (4.13 ± 0.94) mm . The relationship of the gingival curve inflection points of maxillary anterior teeth with the gingival zenith and the contact points were determined in horizontal and vertical ways. In the CI, the mesial IP in X and Y axis were 0.61±0.10 and 0.26±0.07, in distal were 0.57±0.10 and 0.25±0.07. In the LI, the mesial IP in X and Y axis were 0.50±0.10 and 0.23±0.08, in distal were 0.56±0.11 and 0.26±0.08. In the CA, the mesial IP in X and Y axis were 0.52±0.09 and 0.23±0.07, the distal IP were 0.60±0.12 and 0.26±0.08. CONCLUSION: The upper anterior teeth papillae shapes of the different teeth and gingival curves are determined with certain characteristics, and the gingival curve inflection points have some mathematical relationship with the gingival crest and the contact points.

[Method and its application of gingival thickness measurement based on cone-beam computed tomography].

OBJECTIVE: To develop a novel method for obtaining the clear visualization of the gingival profile by cone-beam computed tomography (CBCT) that consistently allows the measurements of gingival thickness and use it to explore the relationship between the gingival thickness and gingival biotype, and the gingival thickness and underlying alveolar bone thickness in the maxillary anterior region. METHODS: In this study, 15 volunteers with healthy gingiva in the maxillary anterior teeth were involved, and a special preparation was done before CBCT scans including making impression with the contrast agent. The tissue biotypes were assessed clinically with the probe, The thickness of both gingiva and bone and the gingival thickness of the cemento-enamel junction (CEJ) were measured radiographically with cone-beam computed tomography scans. All data analyses were performed using SPSS 16.0. RESULTS: The CBCT image showed clear visualization of the gingival profile. The average gingival thickness of the CEJ was (1.22±0.32) mm. A correlation was observed between the tissue biotypes and the gingival thickness (r=0.449,P<0.05). The labial gingival thickness was negative associated with the underlying bone thickness measured with CBCT in the maxillary anterior region (r=-0.31, P=0.021). CONCLUSION: A method was established for measuring gingival thickness based on cone-beam computed tomography. The gingival biotypes had a positive correlation with gingival thickness of the CEJ.

[Preliminary study on measuring interdental papilla height and thickness of the maxillary anterior teeth based on cone-beam computed tomography].

OBJECTIVE: To investigate the features of the fill of interdental spaces by gingival papillae and the associated factors. METHODS: Fifteen volunteers with healthy gingiva were involved in this study. The height and thickness on the alveolar crest level of 62 maxillary anterior papilla were measured radiographically with cone-beam computed tomography (CBCT) scans. A standardized periodontal probe with Williams markings was used for measurements of the papilla width on the alveolar crest level. RESULTS: When the papilla was complete fill interdentally, the mean height of papillary tissue on the alveolar crest level (equal to contact point-bone crest) was (3.67 ± 0.51) mm. The mean thickness of papilla on the alveolar crest level was (8.38 ± 0.75) mm. The papilla height had a positive correlation with papilla thickness (r = 0.433, P < 0.001). CONCLUSIONS: The cone-beam computed tomography can be used for clear visualization of the papilla profile and the measurements of papilla height and thickness. Thicker and wider tissue was associated with an increased likelihood of having a complete papilla fill.

[Preliminary study on gingival biotype by periodontal probing].

OBJECTIVE: To establish a convenient, objective and applicable method to assess gingival biotype using periodontal probing. METHODS: A total of 66 maxillary anterior teeth from 14 volunteers (6 males, 8 females) with healthy gingiva, aged from 20 to 30 years, were recruited in this study. The gingival biotypes were evaluated by whether or not the outline of the periodontal probe was clear inside the gingiva. Gingival thickness of the cemento-enamel junction (CEJ) in upper anterior teeth was measured by cone-beam CT (CBCT). RESULTS: The method of periodontal probing-assessed gingival biotype had good consistency and repeatability. The result of probing-assessed gingival biotype was consistent with that obtained by CBCT. The mean thickness of gingiva in thin, compromised and thick gingival biotype was (1.02 ± 0.20), (1.28 ± 0.25) and (1.46 ± 0.25) mm. These differences were significant for all three comparisons (P = 0.001, respectively). CONCLUSIONS: Periodontal probing-assessed gingival biotype is a simple, relatively objective and suitable method for clinical examination.