[Effect of anatomical parameters of maxillary sinus on the outcomes of transcrestal sinus lift].

OBJECTIVE: To investigate the effect of three anatomical parameters (maxillary sinus width, maxillary sinus angle, and residual bone height) on the outcomes of transcrestal sinus lift with simultaneous implant placement. METHODS: A total of 60 maxillary sinuses in 42 patients were included in this study. All patients were treated with transcrestal sinus lift procedure associated with simultaneous implant placement using a composite graft material of autogenous bone and Bio-Oss. For each patient, beam computed tomography (CBCT) scans were performed preoperatively, immediately after surgery, and 6 months after surgery. The parameters were measured on the preoperative and postoperative CBCT images. The correlation of three anatomical parameters with graft resorption was analyzed using Pearson's correlation test. RESULTS: The average residual bone height was (4.46±1.55) mm. The average width of maxillary sinus was (13.86±2.71) mm. The average sinus angle was 78.09°±10.27°. A significant positive correlation was observed between maxillary sinus width and graft resorption (P<0.01). A positive association was also found between sinus angle and graft resorption (P<0.01). CONCLUSIONS: The findings show that graft bone resorption in elevated sinus has a positive correlation with the sinus width and sinus angle.

Marginal bone loss around non-submerged implants is associated with salivary microbiome during bone healing.

Marginal bone loss during bone healing exists around non-submerged dental implants. The aim of this study was to identify the relationship between different degrees of marginal bone loss during bone healing and the salivary microbiome. One hundred patients were recruited, and marginal bone loss around their implants was measured using cone beam computed tomography during a 3-month healing period. The patients were divided into three groups according to the severity of marginal bone loss. Saliva samples were collected from all subjected and were analysed using 16S MiSeq sequencing. Although the overall structure of the microbial community was not dramatically altered, the relative abundance of several taxonomic groups noticeably changed. The abundance of species in the phyla Spirochaeta and Synergistetes increased significantly as the bone loss became more severe. Species within the genus Treponema also exhibited increased abundance, whereas Veillonella, Haemophilus and Leptotrichia exhibited reduced abundances, in groups with more bone loss. Porphyromonasgingivalis, Treponemadenticola and Streptococcus intermedius were significantly more abundant in the moderate group and/or severe group. The severity of marginal bone loss around the non-submerged implant was associated with dissimilar taxonomic compositions. An increased severity of marginal bone loss was related to increased proportions of periodontal pathogenic species. These data suggest a potential role of microbes in the progression of marginal bone loss during bone healing.

[Characteristics of hydroxyapatite/PMMA nanocomposites for provisional restoration and its biocompatibility with human gingival fibroblasts].

OBJECTIVE: To formulate hydroxyapatite (HA)/polymethyl methacrylate (PMMA) composites with improved cytocompatibility for provisional restoration. METHODS: Nanocomposites with 20 wt%, 30 wt%, 40 wt%, and 50 wt% HA/PMMA (H/P) were developed and examined using X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM). Human gingival fibroblasts were cultured on those HA/PMMA discs and investigated by fluorescent staining on 24 h and MTT assay at 1 d, 3 d, 5 d and 7 d. RESULTS: Chemical integration of HA/PMMA interface was confirmed by XPS. Typical fusiform cells with adhesion spots were detected on 40 wt% and 50 wt% H/P discs. MTT results showed insignificant differences in cell growth between 40 wt% H/P and pure titanium (Ti, P > 0.05), while the other H/P discs showed significantly lower cell growth than pure Ti (P < 0.05). CONCLUSION: 40 wt% H/P might be a promising candidate for provisional dental implant restoration and for esthetic gingival contour.

Investigation of the mechanical properties of a low-shrinkage liquid crystalline matrix combined with nano-hydroxyapatite.

The objective of this study was to investigate the mechanical properties of a low-shrinkage acrylate liquid crystalline resin matrix (ALCRM), (4-3-(acryloyloxy)-2-hydroxypropoxy) phenyl 4-(3-(acryloyloxy)-2-hydroxypropoxy) benzoate, combined with nano-hydroxyapatite (na-HA). The ALCRM monomer and diluent monomer triethylene glycol dimethacrylate (TEGDMA) were mixed at a mass ratio of 7:3 to prepare the resin matrix. The volume shrinkage of the ALCRM/TEGDMA and the traditional resin matrix Bis-GMA (2, 2-bis [4-(3-methacryloxy-2-hydroxypropoxy) phenyl] propane)/TEGDMA were measured. Then 20%, 30%, and 40% na-HA were added to ALCRM/TEGDMA and Bis-GMA/TEGDMA, respectively. Compressive strength (CS) and Vickers hardness (VHN) were tested to identify mechanical properties of the composites. The volume shrinkage of the ALCRM/TEGDMA was 3.60% ± 0.36%, which was lower than that of the traditional resin matrix. Moreover, with the same amount of na-HA filler, the mechanical properties of the ALCRM-based composites were superior to those of Bis-GMA-based composites. ALCRM-based composites exhibited the highest CS and VHN values when the filler content was 30%. These results indicate that the low-shrinkage liquid crystalline resin matrix has strong mechanical properties after incorporating the na-HA. The experimental ALCRM-based composites have promising potential for the development of novel low-shrinkage dental resins with strong mechanical properties.

[Evaluation of clinical therapeutic efficiency of immediate loaded implant].

OBJECTIVE: Clinical cases of immediate loaded implants were retrospectively analyzed, in the aim of evaluating the clinical value of immediate loading. METHODS: From July 2005 to October 2009, 99 immediate loaded implants were implanted in 29 patients. The overall data including radiography, clinical examination were collected during the follow-up periods ranged from 4 to 46 months. The implants were evaluated with the survival rate, bone resorption, soft tissue esthetics (including gingiva papilla index and pink esthetic score). RESULTS: Survival rate for immediate loaded implant was 97.0%. The average bone resorption were 0.22 mm at 4-6 months after surgery, bone increase of 0.15 mm were found at 6-12 month, and bone increase up to 0.16 mm at 12-46 months. The gingival papilla index was 2.68, while pink esthetic score was 12.58. CONCLUSION: Immediate loaded implant is an effective repairing method for patients missing teeth and the esthetics effect is ideal.

[Effect of silver-hydroxyapatite/titania nanocomposites on proliferation, vitality and ultrastructure of osteoblasts].

OBJECTIVE: Osteoblasts behaviors were investigated when cultured in the presence of silver-hydroxyapatite/titania nanoparticles (nAg-HA/TiO2) in vitro. METHODS: Rat calvaria osteoblasts were cultured in the presence of 10 mirog/mL-500 mirog/mL nHA or nAg-HA/TiO2 for 2 h, 6 h, 8 h, 24 h, 72 h and 120 h. Cell proliferation, vitality and ultrastructure were tested using cell counting chamber, MTT assay, and transmission electron microscope (TEM). RESULTS: Both cell proliferation and vitality were restricted by addition of nanoparticles, while the respiration rates as an index for unit cell viability were enhanced. nAg-HA/TiO2 at low concentration showed superiority. No remarkable ultrastructural changes were observed in the osteoblasts exposed to nanoparticles. The differences in cell proliferation and cell vitality between nAg-HA/TiO2 group and nHA group at the same concentration were insignificant. CONCLUSION: nAg-HA/TiO2 restricted cells proliferation, but triggered unit cell viability. Cytocompatibility of nAg-HA/TiO2 is almost the same as that of nHA's.

[Characterization and antibacterial effect of Ag-nHA-nTiO2/polyamide 66 nanocomposite membrane on oral bacteria].

OBJECTIVE: Undried silver-hydroxyapatite-titania (Ag-nHA-nTiO2) nanoparticles slurry was used to make membrane with polyamide 66 (PA66) by co-polymerization method. The purpose of this study is to test the physical and chemical characteristics and antibacterial ability. METHODS: The morphology, chemical components and structures of the membrane were characterized by atomic absorption spectrometer (AAS), X-ray diffraction (XRD), scanning electron microscope (SEM) and energy-dispersive X-ray analysis (EDX). Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), Porphyromonas gingivalis (P. gingivalis), Fusobacterium nucleatum (F. nucleatum) and Streptococcus mutans (S. mutans) were utilized to test the antibacterial effect. RESULTS: XRD results demonstrated that the membrane have characteristic diffraction peaks of pure hydroxyapatite (HA). A homogeneous distribution of the Ca, P, Ti and Ag element in the membrane was confirmed by EDX. Both surface and section showed porous structure which was confirmed by SEM and the average hole size was 20-30 microm. The bacteria assay reflected to the antibacterial effect, 50.10% of S. aureus and 56.31% of E. coli were killed. However, 91.84% of P. gingivalis, 90.64% of F. nucleatum and 90.49% of S. mutans were killed and pictures of SEM showed obviously fewer cells on the surface. CONCLUSION: The nanocomposite membrane could be one of the bioactive materials with antibacterial properties for oral guided bone regeneration technique.

[Study on the microstructure of acellular dermal matrix and its biocompatibility with MG63 osteoblast-like cells].

OBJECTIVE: To study the microstructue of acellular dermal matrix (ADM) and the attachment and proliferation of MG63 osteoblast-like cells on the membrane. METHODS: ADM was experimental group and expanded polytetrafluoroethylene (e-PTFE) membrane was control group. Light microscope and scanning electronic microscope (SEM) were used to observe the microstructure of the two kinds of membrane. MG63 osteoblast-like cells were cultured on the two kinds of membrane and the blank group. The cell viability was checked by cell viability analyzer (CVA) and alkaline phosphatase (ALP) activity was detected by ELISA. SEM was used to observe the adhesion and proliferation of the MG63 osteoblast-like cells on the two kinds of membrane. RESULTS: The ADM was composed of the tissular side and basal lamina side. The tissue side showed scale-shaped structure and the basal lamina side demonstrated many digitations and some pores of folliculus pili. The e-PTFE showed many tiny lined cracks in elliptic structure. The viability of the MG63 osteoblast-like cells on the two kinds of membranes and ALP measurement showed that there was no significant difference between each of the two membrane groups and the blank. The adhesion and proliferation of osteoblast-like cells on the two kinks of membranes were both well. CONCLUSION: ADM has no negative effects on the growth of osteoblast-like cells. ADM is biocompatibile and its microstructure is appropriate for guided bone regeneration materials.

[In vivo study of remineralization with trace elements by laser scanning confocal microscope].

OBJECTIVE: To evaluate in vivo the remineralization containing trace elements. METHODS: The volunteers were selected by pre-designed criteria of adopting and eliminating. Caries-like lesions were prepared in the enamel of extracted human premolars with the use of demineralizing solution. Sections of the normal and lesion enamel (approximately 2 mm x 2 mm) were prepared, with the cut surfaces protected by nail varnish. 2 enamel specimens were mounted in a removable appliance. By measuring lesion parameters (area, total and average dye fluorescence) on a tooth with confocal laser scanning microscopy (CLSM), the effect of remineralization was assessed. Specimens were cut and stained with a fluorescent dye (0.1 mmol/L rhodamine B) for 1 h and analyzed using CLSM. RESULTS: CLSM detected significantly greater remineralization (P < 0.05) in the specimens treated with the trace elements fluoride-containing solution and only containing fluoride (P < 0.05), especially more obvious difference was shown upon remineralized solution with trace elements, which means it produced a greater remineralization. CLSM data of remineralized solution with trace elements were showed: delta Z vs. Area = -50.4 +/- 8.1; delta Z vs. TF = -27.8 +/- 3.8; delta Z vs. AF = -91.5 +/- 8.9. CONCLUSIONS: The ability of remineralization of the new solution is better than that only containing fluoride in in vivo study. It can potentially prevent initiation of caries. This study provides not only the theoretical foundation for clinical application, but also shows a new kind of experimental method in the study of demineralization and remineralization.