Jaw defects caused by various reasons often seriously affect appearance and function. The goal of the treatment of oral and maxillofacial tumors should include the cure of the tumor and the restoration of premorbid function. The development of microsurgery and digital surgery technology has promoted the development of jaw reconstruction with vascularized free bone flap. Good appearance and improved predictability could be obtained with the help of preope-rative visual design. How to rehabilitate occlusal function on the reconstructed jaw and improve the quality of life of patients has become an important research direction. This article discusses the challenge of jaw reconstruction, the selection of vascularized bone flap, the choice of implant timing, the treatment of peri-implant soft tissue, and the influence of radiotherapy on implants after jaw reconstruction.
Humans ; Dental Implants ; Plastic Surgery Procedures ; Free Tissue Flaps/surgery* ; Quality of Life ; Dental Implantation, Endosseous ; Fibula/surgery* ; Bone Transplantation ; Mandibular Reconstruction

When selecting implant guidance methods or judging whether the patient can be implanted, many doctors ignore or only use visual inspection to estimate a patient's mouth opening. This phenomenon often leads to failure to complete the implantation due to insufficient mouth opening or the deflection of the implant due to limited angle, resulting in the high incidence of corresponding complications. The main reason is that doctors lack accurate analysis and control of the overall geometric conditions of the intraoral surgical area, and three-dimensional position blocking of surgical instruments occurs during the operation. In the past, mouth opening was defined as the distance between the incisor edges of the upper and lower central incisors when the patient opens his mouth widely, and the implant area could be in any missing tooth position. When it is in the posterior tooth area, the specific measurement scheme of the mouth opening could not be simply equivalent to the previous measurement method in the anterior tooth area. However, how to measure quickly and conveniently the mouth opening of any surgical area to determine whether it could be implanted and meet the needs of the selected guidance method remains unclear. This paper introduces new concepts, establishes new classification and corresponding accurate measurement scheme of implant area, and establishes a decision tree of implant methods guided by the actually measured value. Results provide a quantitative basis for rational formulation and implementation of implant treatment.
Humans ; Mouth ; Dental Implantation, Endosseous/methods* ; Incisor ; Clinical Decision-Making ; Dental Implants

OBJECTIVES: The current study aimed to investigate the bonding properties of a novel low-shrinkage resin adhesive containing expanding monomer and epoxy resin monomer after thermal cycling aging treatment. METHODS: Expanding monomer of 3,9-diethyl-3,9-dimethylol-1,5,7,11-tetraoxaspiro-[5,5] undecane (DDTU) as an anti-shrinkage additive and unsaturated epoxy monomer of diallyl bisphenol A diglycidyl ether (DBDE) as a coupling agent were synthesized. A blend of DDTU and DBDE at a mass ratio of 1∶1, referred to as "UE", was added into the resin matrix at the mass fraction of 20% to prepare a novel low-shrinkage resin adhesive.Then, the methacrylate resin adhesive without UE was used as the blank control group, and a commercial resin adhesive system was selected as the commercial control group. Moreover, the resin-dentin bonding and micro-leakage testing specimens were prepared for the thermal cycling aging treatment. The bonding strength was tested, the fracture modes were calculated, the bonding fracture surface was observed by scanning electron microscope (SEM), and the dye penetration was used to evaluate the tooth-restoration marginal interface micro-leakage. All the data were analyzed statistically. RESULTS: After aging, the dentin bonding strength of the experimental group was (19.20±1.03) MPa without a significant decrease (P>0.05), that of the blank control group was (11.22±1.48) MPa with a significant decrease (P<0.05) and that of the commercial control group was (19.16±1.68) MPa without a significant decrease (P>0.05). The interface fracture was observed as the main fracture mode in each group after thermal cycling by SEM. The fractured bonding surfaces of the experimental group often occurred on the top of the hybrid layer, whereas those of the blank and commercial control groups mostly occurred on the bottom of the hybrid layer. Micro-leakage rating counts of specimens before and after thermal cycling were as follows: the experimental group was primarily 0 grade, thereby indicating that a relatively ideal marginal sealing effect could be achieved (P>0.05); meanwhile, the blank control group was primarily 1 grade, and the penetration depth of dye significantly increased after thermal cycling (P<0.05); the commercial control group was primarily 0 grade without statistical difference before and after thermal cycling (P>0.05), while a significant difference was observed between the commercial control group and experimental group after thermal cycling (P<0.05). CONCLUSIONS The novel low-shrinkage resin adhesive containing 20%UE exhibited excellent bonding properties even after thermal cycling aging treatment, thereby showing a promising prospect for dental application.
Composite Resins ; Dental Bonding ; Dental Cements ; Surface Properties ; Resin Cements ; Dentin-Bonding Agents ; Dentin ; Materials Testing ; Microscopy, Electron, Scanning

OBJECTIVES: This study aimed to evaluate the long-term clinical efficacy of simple taper retentive implants in the posterior dental area after immediate implantation for 5-7 years. METHODS: Selected from January 2015 to December 2017 in the Fourth Affiliated Hospital of Nanchang University dental clinic line tooth area immediately after the implant prosthesis, a total of 38 patients, 53 implants, were deep into (bone under 2 mm or higher) and the upper structure was repaired. In addition, after the completion of tracking observation of 60-90 months, the implant surrounding bone health was recorded and analyzed. RESULTS: After 5-7 years of follow-up, 1 of the 53 implants failed to fall out, and the implant retention rate was 98.1%. The amount of bone resorption in the proximal and distal margins 5-7 years after implant restoration was (0.16±0.94) mm and (-0.01±1.29) mm, respectively, and the difference in bone height between the proximal and distal margins of the implant and the immediate post-restoration period was not statistically significant (P>0.05). No statistically significant differences were found in the effects of periodontitis, implant site inflammation, and smoking on peri-implant marginal bone resorption (P>0.05). CONCLUSIONS The single taper-retained implant broadens the indications for immediate implant placement in the posterior region, and its deep sub-osseous placement (≥2 mm below the bone) avoids to a certain extent the disturbance of the implant by external stimuli and the exposure of the cervical abutment of the implant, with the good long-term stability of the marginal bone around the implant.
Humans ; Dental Implantation, Endosseous ; Dental Implants ; Immediate Dental Implant Loading ; Follow-Up Studies ; Dental Implants, Single-Tooth ; Alveolar Bone Loss/surgery* ; Treatment Outcome ; Dental Prosthesis, Implant-Supported ; Dental Restoration Failure

OBJECTIVES: To investigate the effect of oral microscope-assisted surface decontamination on implants in vitro. METHODS: Twelve implants that fell off because of severe peri-implantitis were collected, and decontamination was carried out on the surfaces of implants through curetting, ultrasound, titanium brushing, and sandblasting at 1×, 8×, or 12.8× magnifications. The number and sizes of residues on the implants' surfaces after decontamination were determined, and the decontamination effect was analyzed according to the thread spacing in the different parts of the thread. RESULTS: 1) The 8× and 12.8× groups scored lower for implant surface residues than the 1× group (P<0.000 1), and the 12.8× group scored lower than the 8× group (P<0.001); 2) no difference in residue score was found between the wide and narrow thread pitch (P>0.05), and the 8× and 12.8× groups had lower scores than the 1× group (P<0.001); 3) the lowest number of contaminants was observed at the tip of the thread, whereas the highest was observed below the thread, and the difference was significant (P<0.001). However, the thread pitch had no effect on the number of contaminants in different areas (P>0.05); 4) the residue scores of the 8× and 12.8× groups were lower than those of the 1× group at the thread tip and above, sag, and below the thread of the implants (P<0.05). CONCLUSIONS Residues on the surfaces of contaminated implants can be effectively removed by using an oral microscope. After decontamination, the residues of pollutants were mainly concentrated below the thread of the implants, and the thread pitch of the implants had no significant effect on the residues.
Humans ; Dental Implants ; Decontamination ; Surface Properties ; Peri-Implantitis ; Titanium

Znic (Zn) alloys with good cytocompatibility and suitable degradation rate have been a kind of biodegradable metal with great potential for clinical applications. This paper summarizes the biological role of degradable Zn alloy as bone implant materials, discusses the mechanical properties of different Zn alloys and their advantages and disadvantages as bone implant materials, and analyzes the influence of different processing strategies (such as alloying and additive manufacturing) on the mechanical properties of Zn alloys. This paper provides systematic design approaches for biodegradable Zn alloys as bone implant materials in terms of the material selection, product processing, structural topology optimization, and assesses their application prospects with a view to better serve the clinic.
Orthopedics ; Zinc ; Alloys ; Dental Materials ; Prostheses and Implants

OBJECTIVE: To analyze the cement flow in the abutment margin-crown platform switching structure by using the three-dimensional finite element analysis, in order to prove that whether the abutment margin-crown platform switching structure can reduce the inflow depth of cement in the implantation adhesive retention. METHODS: By using ANSYS 19.0 software, two models were created, including the one with regular margin and crown (Model one, the traditional group), and the other one with abutment margin-crown platform switching structure (Model two, the platform switching group). Both abutments of the two models were wrapped by gingiva, and the depth of the abutment margins was 1.5 mm submucosal. Two-way fluid structure coupling calculations were produced in two models by using ANSYS 19.0 software. In the two models, the same amount of cement were put between the inner side of the crowns and the abutments. The process of cementing the crown to the abutment was simulated when the crown was 0.6 mm above the abutment. The crown was falling at a constant speed in the whole process spending 0.1 s. Then we observed the cement flow outside the crowns at the time of 0.025 s, 0.05 s, 0.075 s, 0.1 s, and measured the depth of cement over the margins at the time of 0.1 s. RESULTS: At the time of 0 s, 0.025 s, 0.05 s, the cements in the two models were all above the abutment margins. At the time of 0.075 s, in Model one, the gingiva was squeezed by the cement and became deformed, and then a gap was formed between the gingiva and the abutment into which the cement started to flow. In Model two, because of the narrow neck of the crown, the cement flowed out from the gingival as it was pressed by the upward counterforce from the gingival and the abutment margin. At the time of 0.1 s, in Model one, the cement continued to flow deep inside with the gravity force and pressure, and the depth of the cement over the margin was 1 mm. In Model two, the cement continued to flow out from the gingival at the time of 0.075 s, and the depth of the cement over the margin was 0 mm. CONCLUSION When the abutment was wrapped by the gingiva, the inflow depth of cement in the implantation adhesive retention can be reduced in the abutment margin-crown platform switching structure.
Finite Element Analysis ; Cementation/methods* ; Gingiva ; Crowns ; Dental Abutments ; Dental Cements ; Dental Stress Analysis

OBJECTIVE: To compare the efficiency and effect of establishing rat peri-implantitis model by traditional cotton thread ligation and local injection of Porphyromonas gingivalis lipopolysaccharide (LPS) around the implant, as well as the combination of the two methods. METHODS: Left side maxillary first molars of 39 male SD rats were extracted, and titanium implants were implanted after four weeks of healing. After 4 weeks of implant osseointegration, 39 rats were randomly divided into 4 groups. Cotton thread ligation (n=12), local injection of LPS around the implant (n=12), and the two methods combined (n=12) were used to induce peri-implantitis, the rest 3 rats were untreated as control group. All procedures were conducted under 5% isoflurane inhalation anesthesia. The rats were sacrificed 2 weeks and 4 weeks after induction through carbon dioxide asphyxiation method. The maxilla of the rats in the test groups were collected and marginal bone loss was observed by micro-CT. The gingival tissues around the implants were collected for further real time quantitative PCR (RT-qPCR) analysis, specifically the expression of tumor necrosis factor-alpha (TNF-α) as well as interleukin-1β (IL-1β). The probing depth (PD), bleeding on probing (BOP) and gingival index (GI) of each rat in the experimental group were recorded before induction of inflammation and before death. RESULTS: After 4 weeks of implantation, the osseointegration of implants were confirmed. All the three test groups showed red and swollen gums, obvious marginal bone loss around implants. After 2 weeks and 4 weeks of inflammation induction, PD, GI and BOP of the three test groups increased compared with those before induction, but only BOP was statistically significant among the three test groups (P < 0.05). At the end of 2 weeks of inflammation induction, marginal bone loss was observed at each site in the cotton thread ligation group and the combined group. At each site, the bone resorption in the combined group was greater than that in the cotton thread ligation group, but the difference was not statistically significant (P > 0.05), bone resorption was observed at some sites of some implants in LPS local injection group. At the end of 4 weeks of inflammation induction, marginal bone loss was observed at all sites in each group. The marginal bone loss in the cotton thread ligation group and the combined group was greater than that in the LPS local injection group, and the difference was statistically significant (P < 0.05). At the end of 2 weeks and 4 weeks of induction, the expression of TNF-α and IL-1β in the test groups were higher than those in the control group (P < 0.05). CONCLUSION Compared with local injection of LPS around the implant, cotton thread ligature and the two methods combined can induce peri-implantitis in rats better and faster.
Animals ; Male ; Rats ; Alveolar Bone Loss/etiology* ; Dental Implants/adverse effects* ; Inflammation ; Lipopolysaccharides ; Peri-Implantitis/pathology* ; Rats, Sprague-Dawley ; Tumor Necrosis Factor-alpha

OBJECTIVE: To describe the submucosal microbial profiles of peri-implantitis and healthy implants, and to explore bacteria that might be correlated with clinical parameters. METHODS: In the present cross-sectional study, 49 patients were recruited. Each patient contributed with one implant, submucosal biofilms were collected from 20 healthy implants and 29 implants with peri-implantitis. DNA was extracted and bacterial 16S ribosomal RNA (16S rRNA) genes were amplified. Submucosal biofilms were analyzed using 16S rRNA sequencing at Illumina MiSeq platform. Differences between the groups were determined by analyzing α diversity, microbial component and microbial structure. The potential correlation between the bacteria with pocket probing depth (PPD) of peri-implant calculated by Spearman correlation analysis. RESULTS: The α diversity of submucosal microbial of health group was significantly lower than that in peri-implantitis group (Chao1 index: 236.85±66.13 vs. 150.54±57.43, P < 0.001; Shannon index: 3.42±0.48 vs. 3.02±0.65, P=0.032). Principal coordinated analysis showed that the submucosal microbial structure had significant difference between healthy and peri-implantitis groups [R²=0.243, P=0.001, analysis of similarities (ANOSIM)]. Compared with healthy implants, relative abundance of periodontal pathogens were higher in peri-implantitis, including members of the red complex (Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola) and some members of orange complex (Precotella intermedia, Eubacterium nodatum, Parvimonas micra), as well as some new periodontal pathogens, such as Fillifactor alocis, Fretibacterium fastidiosum, Desulfobulbus sp._HMT_041, and Porphyromonas endodontalis. Spearman correlation analysis revealed that the relative abundance of Treponema denticola (r=0.686, P < 0.001), Tannerella forsythia (r=0.675, P < 0.001), Fretibacterium sp. (r=0.671, P < 0.001), Desulfobulbus sp._HMT_041 (r=0.664, P < 0.001), Filifactor alocis (r=0.642, P < 0.001), Fretibacterium fastidiosum (r=0.604, P < 0.001), Porphyromonas gingivalis (r=0.597, P < 0.001), Porphyromonas endodontalis (r=0.573, P < 0.001) were positive correlated with PPD. While the relative abundance of Rothia aeria (r=-0.615, P < 0.001) showed negatively correlation with PPD. CONCLUSION Marked differences were observed in the microbial profiles of healthy implants and peri-implantitis. The members of red and orange complex as well as some new periodontal pathogens seem to play an important role in peri-implant disease. Compared with healthy implants, the submucosal microbial of peri-implantitis were characterized by high species richness and diversity.
Humans ; Peri-Implantitis/microbiology* ; Cross-Sectional Studies ; RNA, Ribosomal, 16S/genetics* ; Bacterial Load ; Porphyromonas gingivalis ; Dental Implants

OBJECTIVE: To study microstructure, friction and wear behaviors of silicon-lithium spray coating on the surface of zirconia ceramics and to preliminarily evaluate its esthetic so as to provide support and guidance for the clinical application. METHODS: Zirconia ceramic specimens were randomly divided into three groups: coating group (two subgroups), polishing group (two subgroups), and glazing group (four subgroups), with 10 samples in each subgroup. The two subgroups of coating group were the zirconia ceramics with the untreated and preliminary polishing surfaces sprayed with silicon-lithium coating, respectively. The two subgroups of polishing group were preliminary polishing and fine polishing of zirconia ceramics, respectively. The four subgroups of glazing group were preliminarily polished zirconia ceramics glazed with Biomic and Stain/Glaze products, respectively; and untreated zirconia ceramics glazed with Biomic and Stain/Glaze products, respectively. The above 8 subgroups of zirconia ceramic specimens were used as friction pairs with 80 steatite ceramics for 50 000 chewing cycles under 50 N vertical load and artificial saliva lubrication using chewing simulation. Scanning electron microscope was used to observe the microstructure of the surface and section of the coating group, and the thickness of the coating and glazing were measured. The linear roughness of the coating and polishing groups was mea-sured using a laser confocal scanning microscope. Vickers hardness was measured using a microhardness tester and the esthetic of zirconia ceramic full crown sprayed with silicon-lithium coating was preliminarily evaluated. White light interferometer was used to measure the width, the maximum depth and the volume of the wear scars of each group, and the wear depth of steatite ceramics and wear rate of zirconia ceramic specimens were calculated. Kruskal-Wallis nonparametric test and Dunn's multiple comparisons test were used to analyze the wear depth of each group (α=0.05). RESULTS: The microstructures of the silica-lithium spray coatings on the untreated and preliminarily polished zirconia ceramic surfaces showed the protruding defects, and the line roughness of coating group was larger than that of the polishing group. The median thickness of the silica-lithium spray coating on the preliminarily polished zirconia ceramic was 13.0 μm (interquartile range, IQR: 11.6, 17.9), while that of the silica-lithium spray coating on the untreated zirconia ceramic was 4.4 μm (IQR: 4.1, 4.7). The Vickers hardness and wear rate of the coating group were between the polishing group and the glazing group. The wear depths of the wear scars of steatite ceramics were the glazing group, coating group, and polishing group in descending order, and there was statistically significant difference between glazing and polishing groups (P < 0.05). With the increase of polishing procedure, the wear depth of steatite ceramics decreased in each subgroups. The orders of maximum depth and volume of wear scars of zirconia ceramic were the glazing group, coating group, and polishing group in descending order, and there was statistically significant difference in the maximum depth of wear scars between glazing and polishing groups (P < 0.05). CONCLUSION The silica-lithium spray coating on the zirconia ceramic, can be used as a new method for zirconia ceramic surface treatment, because it can increase the esthetic of zirconia ceramics compared with polishing and reduce the wear of steatite ceramics compared with glazing.
Humans ; Silicon ; Materials Testing ; Friction ; Lithium ; Cicatrix ; Surface Properties ; Silicon Dioxide ; Zirconium/chemistry* ; Ceramics ; Dental Porcelain