Cone-beam computed tomography-based analysis of maxillary sinus pneumatization extended into the alveolar process in different age groups.

OBJECTIVE: This study aimed to measure the amount of maxillary sinus pneumatization (MSP) extended into alveolar processes in different age groups via cone-beam computed tomography (CBCT) and its association with age. METHODS: The data of 293 adult patients (533 maxillary sinuses) who underwent CBCT at our hospital from January 2020 to October 2020 were analyzed and divided into the following age groups: group I (18-34 years old, youth group), group II (35-59 years old, middle-aged group) and group III (≥ 60 years old, elderly group). The distance between the lowest point of the maxillary sinus floor and nasal cavity floor in the central area of the maxillary posterior teeth was measured and recorded as the amount of MSP. Further, according to the positional relation between the maxillary posterior teeth and maxillary sinus floor, MSP was divided into type I (normal pneumatization) and type II (extensive pneumatization). The distribution of pneumatization types and degree and change of pneumatization for the different age groups were also analyzed. P < 0.05 was used as the threshold for statistical significance. RESULTS: The amount of MSP of group I [(3.75 ± 3.77) mm] was significantly higher than that of group II [(2.30 ± 4.48) mm] and group III [(2.09 ± 4.70) mm], but there was no significant difference between group II and group III. We also found that the amount decreased gradually with increasing age (rs = - 0.2), with the youth group showing a higher prevalence of extensive pneumatization (youth vs. middle-age vs. elderly: 66.44% vs. 36.81% vs. 22.28%, respectively). There was no statistically significant difference in the amount of MSP between males and females and between left and right maxillary sinus in each group (P > 0.05). CONCLUSION: The amount of MSP was significantly higher in the 18-34 years old group compared to older age groups, showed a decreasing trend with age and was not associated with sex and maxillary sinus sides.

Self-swelling tissue expander for soft tissue reconstruction in the craniofacial region: An in vitro and in vivo evaluation.

BACKGROUND: Craniofacial soft-tissue defects mostly have an impact on the treatment of various oral diseases. Tissue expander is an important technique for tissue reconstruction, especially for soft tissues in reconstructive surgery. OBJECTIVE: This research aimed to develop a new self-swelling tissue expander, namely hydrogel, for soft tissue reconstruction in craniofacial region. METHODS: In vitro, the chemical and physical characteristics of hydrogel were evaluated by SEM, swelling rate, mechanical testing, EDS, and FT-IR. In vivo, the craniofacial implant model of SD rats were divided into group A as control, group B with hydrogels for 1 week expansion, group C for 2 weeks and group D for 4 weeks (n = 5), and the effects were analyzed by HE staining, histological and radiographic evaluation. RESULTS: The in vitro results suggested that dry hydrogel possessed a uniform surface with micropores, the surface of post-swelling hydrogel formed three-dimensional meshwork. Within 24 hours, hydrogels expanded markedly, then slowed down. The mechanical property of hydrogels with longer expansion was better, whose main elements were carbon and oxygen. FT-IR also verified its molecular structure. In vivo, the wounds of rats recovered well, hydrogels could be removed as one whole piece with original shape and examined by radiographic evaluation, besides, the expanded skin and developed fibrous capsule formed surrounding hydrogels. CONCLUSION: The new expander was designed successfully with good chemical and physical characteristics, and could be applied in an animal model to help tissue reconstruction.

Preparation and antibacterial properties of La-doped TiO2 films on 3Y-TZP ceramic surface / 口腔疾病防治

Objective @#To prepare the La-doped TiO2 film on the surface of 3Y-TZP ceramics in order to observe its antibacterial properties, providing an experimental basis for the application of antibacterial zirconia ceramics in the clinic.@*Method@# A cylindrical 3Y-TZP specimen with a diameter of 20 mm and a height of 3 mm was prepared. The sol-gel method was used to prepare 1% lanthanum (La)-doped TiO2 sol, and the La-TiO2 film-3Y-TZP ceramic was prepared by dip coating on the surface of 3Y-TZP. The TiO2 thin film-3Y-TZP ceramic was prepared by adding no lanthanum nitrate solution in the same way. The surface morphology of 3Y-TZP ceramic specimens (3Y-TZP group), TiO2 thin film-3Y-TZP ceramic specimens (TiO2 film group), and La-TiO2 thin film-3Y-TZP ceramic specimens (La-TiO2 film group) was observed by scanning electron microscopy, and photocatalysis, antibacterial and cytotoxicity experiments were carried out. For the photocatalytic experiment, four specimens were randomly selected from the La-TiO2 film group and TiO2 film group to observe the degradation rate of methylene blue at different time points under sunlight. In the antimicrobial experiment, five specimens were randomly selected from the La-TiO2 film group, TiO2 film group and 3Y-TZP group. The antimicrobial activity of each group was tested using the bacteriostatic circle method, and the bacteriostatic distance of each group was compared. In the cytotoxicity experiment, three samples were randomly selected from the La-TiO2 film group, TiO2 film group and 3Y-TZP group (negative control group), and the extracts were prepared. Here, 0.064% phenol solution were served as the positive control group. Morphological observation of L-929 cells in four groups was performed after 3 d of culture. Cell viability and relative cell proliferation were measured by MTT assay.@*Results@#La-TiO2 films with uniform distribution can be prepared on a 3Y-TZP surface by the dipping-drawing method. Photocatalytic experiments showed that the degradation rate of methylene blue in the La-TiO2 film group was (41.2 ± 1.5)% in daylight for 2 hours, which was higher than that in TiO2 film group (36.5 ± 2.4)%. A significant difference was noted between the two groups (t=3.321, P=0.016). The antimicrobial experiment showed that the antimicrobial distance of La-TiO2 group was (0.34 ± 0.08) mm, which was larger than that of TiO2 group (0.12 ± 0.02) mm. No obvious antimicrobial circle was noted in 3Y-TZP group, and the antimicrobial distance of the La-TiO2 film group was larger than that of TiO2 film group (F=63.798, P < 0.001). Cytotoxicity test showed that the relative proliferation rate of cells in La-TiO2 film group was (89.5 ± 1.3)%, and the cytotoxicity rating was grade 1. Significant differences were noted among the four groups (F=68.250, P < 0.001).@*Conclusion @#The La-doped TiO2 film can improve its photocatalytic activity and enhance the antibacterial activity of 3Y-TZP without obvious cytotoxicity.

MicroRNA-1-3p inhibits the proliferation and migration of oral squamous cell carcinoma cells by targeting DKK1.

We investigated the functional role and mechanism of miR-1-3p and DKK1 in oral squamous cell carcinoma (OSCC) cells. The level of miR-1-3p and DKK1 expression were detected in OSCC tissues and cells using reverse-transcription - quantitative PCR and Western blot. A dual luciferase reporter gene assay was applied to confirm the targeting relationship between miR-1-3p and DKK1. Functional assays, including MTT, Transwell, colony formation, and flow cytometry analysis were conducted to verify their effect on cell progressions. MTT, colony formation, and Transwell assays indicated that the proliferation, migration, and invasion of SCC-4 cells was impaired with high miR-1-3p expression but promoted with high DKK1 expression. The results from cell cycle analysis and annexin-V-PI assays for apoptosis suggested that miR-1-3p suppressed the transit of SCC-4 cells from G0/G1 to S and induced apoptosis. In summary, miR-1-3p suppressed the progression of OSCC by inhibiting DKK1 expression.

[Effect of different polymerization methods on shear bond strength between polymethyl methacrylate and silicone soft liner].

OBJECTIVE: To compare shear bond strength (SBS) between two types of silicone soft liner and polymethyl methacrylate (PMMA) under the condition of heat curing and room temperature curing. METHODS: A total of 48 PMMA specimens (50 mm x 10 mm x 3 mm) were made by water-bath heating method, and randomly divided into four groups. By using Ufi Gel P (UGP) as soft liner material, group A1 was prepared under heat curing, and group A2 was prepared under room temperature curing. To form the other two groups, Silagum-Comfort (SLC) as soft-liner material was used. Group B1 was prepared under heat curing, and group B2 was prepared under room temperature curing. Shear bond strength (SBS) was tested by using the electronic universal testing machine. The adhesives layer and surface of silastic and PMMA were observed by optical microscope and scanning electron microscopy (SEM). RESULTS: The SBS of groups A1, A2, B1, B2 were (2.39 +/- 0.24), (1.74 +/- 0.27), (3.09 +/- 0.26), and (2.21 +/- 0.29) MPa, respectively. Significant differences were found between A1 and A2, B1 and B2, A1 and B1, and A2 and B2 (P < 0.05). Optical microscope showed numerous bubbles in the cured UGP, and no air bubbles in the SLC. The surface of PMMA was rough. SEM images showed that each group had continual consistent adhesive interface and a whisker hump on the adhesive layer of A2 and B2. CONCLUSION: The SBS ofUGP, SLC, and PMMA achieved minimum clinical standard of 0.44 MPa. The SBS of UGP and PMMA were higher than that of SLC and PMMA. The polymerization method of heat curing was higher than room temperature curing.

[Color stability of ceromer veneers/resin cements after accelerated ageing].

OBJECTIVE: To investigate the color stability of ceromer veneers/resin cements after accelerated ageing, and to provide the reference for clinical application and choice. METHODS: Fifteen groups of ceromer veneers/resin cements samples, five samples in each group, were prepared as experimental groups.In the fifteen groups, ceromer veneers in three thickness (1.00, 0.75, 0.50 mm) and resin cements of five shades(A1,A3, B 0.5, WO, TR), were matched through permutation and combination. Three groups of ceromer veneers with different thickness (1.00, 0.75, 0.50 mm) were used as control groups. All samples were put into xenon lamp ageing instrument to accelerate ageing.Spectrophotometer were used to measure the lightness(L(*)), red green color(a(*)) and blue yellow color(b(*)) of samples before and after accelerated ageing process, and the change of lightness (ΔL) , red green color (Δa) , blue yellow color (Δb) and color variation(ΔE) were calculated.We investigated the effect of thickness of ceromer veneer and color of resin cement on color variation by using analysis of variance. RESULTS: The thickness factor and color factor showed significant effect on ΔE values, and they have interaction (P < 0.05). The ΔE values of all experimental groups were lower than 3.3. After accelerated ageing, all L(*) values of experimental groups decreased, and ΔL values were lower than 2.0. CONCLUSIONS: The thickness of ceromer veneer and the color of resin cement could both affect the color stability of ceromer veneers/resin cements. The changes of lightness and color in ceromer veneers/resin cements were considered clinically acceptable after accelerated ageing.

[Occlusal reconstruction of a patient with hypohidrotic ectodermal dysplasia].

Prosthodontic treatment for patient with hypohidrotic ectodermal dysplasia (HED) is difficult to manage because of the loss of occlusal vertical dimension, abnormal alveolar ridge and anodontia A 20-year-old case with HED was reported. The patient was treated with occlusal reconstruction by a maxillary fixed prosthesis and mandibular telescopic prosthesis. At one-year's follow-up, dentures were well used and occlusal function of the patient returned to normal.

[The influence of methacryloxy propyl trimethoxyl silane on shear bond strength of three kinds metal and Filtek resin].

OBJECTIVE: To study the influence of three different metal alloy surfaces treated with primer methacryloxy propyl trimethoxyl silane (gamma-MPS) coupling agent on the bond strength of Filtek Z350 resin. METHODS: Total 36 specimens of nickel-chromium(Ni-Cr) alloy, pure titanium(Ti) and aurum-palladium(Au-Pd) alloy, each of 12 pieces produced by lost wax casting method, were divided into 6 groups. After treated with gamma-MPS on the bonding surface, experimental group samples were adhered to Filtek Z350 resin, then compared with the surface without gamma-MPS treatment. The tensile and shear strength of each group tested and the fracture sections were observed with scanning electron microscope (SEM). RESULTS: Comparing the Ni-Cr alloy and pure Ti experimental group with them in control group, the shearing strength of the experimental group was higher, and the differences were significant (P < 0.001). The shearing strength of the experimental group and control group of Au-Pd alloy were not significant (P > 0.05). Comparing the experimental groups, the shearing strength of pure Ti was higher than Ni-Cr alloy, both were higher than Au-Pd alloy (P < 0.01). These entire specimens were adhesive fracture. Comparing with the control group, Ni-Cr alloy and pure Ti experimental group showed more resin juts in the fracture surface, while the Au-Pd alloy in experimental group showed less resin juts. CONCLUSION: gamma-MPS can enhance the adhesion between metal and resin, but it is also related to the metal composition. gamma-MPS can significantly increase the bond strength of resin and Ti or Ni-Cr alloy, but not the case of Au-Pd alloy and resin.

[Prosthodontic treatment on mandibular fracture with poor healing: a case report].

A mandibular fracture case of twice internal fixation surgery with poor healing was treated by denture prosthodontics in Affiliated Stomatological Hospital of Nanchang University. The profile of maxillofacial region was improved, the masticatory function was enhanced, and the new bone formation was promoted.

[The influence of gilt to the retention of the complete metal crown].

OBJECTIVE: To research the influence of gilt to the retention of the complete metal crown. METHODS: Sixty Ni-Cr alloy complete metal crown were divided into three groups, control group (common Ni-Cr alloy complete metal crown), whole gold-plating group (whole gilding on the tissue surface of the inner Ni-Cr alloy complete metal crown), partial gold-plating group (gilding on the tissue surface of 1/3 cervical inner Ni-Cr alloy complete metal crown). The retention force of complete metal crown was measured by tensile force/pressure ergograph. RESULTS: The retention force of control group, partial gold-plating group, whole gold-plating group were (657 +/- 151) N, (632 +/- 139) N, (569 +/- 103) N, respectively. There were significant differences between control group and whole gold-plating group, whole gold-plating group and partial gold-plating group (P < 0.05). There was no significant difference between control group and partial gold-plating group (P > 0.05). CONCLUSION: The force of retention would decrease after gilding on the tissue surface of the inner Ni-Cr alloy complete metal crown, but have no influence to normal retention requirement of complete crown. Although the retention of partial gold-plating complete metal crown had somewhat decrease, it could be ignored.

[An in vitro investigation of wear resistance and hardness of three kinds of new composite resins].

OBJECTIVE: To evaluate wear resistance and hardness of three kinds of new composite resins. METHODS: Three kinds of new composite resins, Solidex, Spectrum, Filtek Z350, were tested. Enamel as control group. A refited MG-200 wear machine was used in this study. Scanning electron microscope (SEM) was used to observe the friction surface of each tested material. Hardness of each tested material was determined by Vickers indentation technique. The data of wear and hardness were analyzed by Mann-Whitney test and 1-way ANOVA. The relationship between the hardness of the composites and the amount of wear of them was determined by a regression analysis method. RESULTS: Filtek Z350 showed the lowest volumetric wear and highest Vickers hardness in the composites (P < 0.05). No significant differences in wear and hardness were observed between Solidex and Spectrum (P > 0.05). Significant relationships were observed between the hardness of the composites and the amount of wear of them (r = 0.968 6) (P < 0.05). Different wear characters of the friction surface of the tested materials were observed by SEM. CONCLUSION: Nanofilled composite was superior to the hybrid composite in wear resistance and hardness.

[Clinical evaluation of two types of fixed partial denture impressions].

OBJECTIVE: To evaluate the clinic effects of alginate impression and agar/alginate combined impression. METHODS: 237 patients of fixed partial denture were collected and divided into group A and group B. Group A was taken impression by aglinate impression, including 81 patients (207 abutments). Group B was taken impression by agar/alginate combined impression, include 156 patients (392 abutments). The impressions were observed by megaloscope, and the number of abutment, the types and number of defect were recorded. RESULTS: In the aglinate impressions, 57.0 percent of abutment had some defect. But in the agar/alginate combined impressions, 36.0 percent of abutment had some defect. There were significant difference between group A and group B in the abutment, air bubbles in cervical margin, unsharpness of the gingival sulcus and shoulders (P<0.05). There were no significant difference between group A and group B in the split and defect of the impressions on the cervical margin. CONCLUSION: There were less defects in the agar/alginate combined impression than in the alginate impression.