Recently,intraoral digital impression technique has been one of the focus in oral medicine.Compared with the model digital impression technique,the intraoral digital impression technique is convenient,fast,real-time and flexible.It can greatly improve the comfort degree of patients and has obvious advantages over traditional technique.At the same time,intraoral digital impression technique also faces severe challenges of complex oral scanning environment,and the bottleneck problem in optical scanning should be solved urgently to seek new breakthroughs in scanning precision.In this paper,the advantages and limitations of intraoral digital impression technique were listed,and clinical indications were analyzed to guide the clinical application.The principles of the mainstream technique and their current clinical application were introduced to let the readers have more comprehensive understanding for intraoral digital impression technique.

Objective To construct lentiviral vectors of GDF15 gene overexpression.Methods Based on the mRNA sequence of GDF15 gene,the GDF15 gene was made.The overexpression vectors were constructed and transfected into competent cells which were detected by sequencing.The 293T cells were transfected by the recombinant lentiviral vectors to achieve the lentivirus packaging production.The lentiviruses were transfected into 293T cells.The expression of GDF15 gene in 293T cell was detected by Western blot in order to determine the validity of GDF15 gene overexpression.Results It was confirmed by sequencing that the GDF15 gene was correctly inserted into the vectors,and that the GDF15 gene overexpressed lentiviral vectors were successfully constructed.After the lentiviruses transfected 293T cells,the expression of GDF15 gene increased significantly at protein level.Conclusions The lentiviral vectors of GDF15 gene overexpression were constructed successfully,and they efficiently up-regulated the expression of GDF15 in 293T cells.

Objective To study the effect of hypoxia/reoxygenation on the the expressions of COX-2 and PGE2 in lipopolysaccharide-inducedind human periodontal ligament cells. Methods Human periodontal ligament cells were first induced by 1 μg/mL lipopolysaccharide. Then cells were divided into two experiment groups: hypoxia group and reoxygenation group. In the hypoxia group, cells were cultured in 1% O2 for 6, 12, 24, 48 h, respectively. In the re-oxygenation group, cells were first cultured under the samecondition as the hypoxia group and then returned to normoxic condition for 24 hours. The expression of COX-2 was detected by Wesrtern Blootting and PGE2 was observed by ELISA.Results The expression of COX-2 was higher in the hypoxia group compared to the control group and reached the peak at 24 h. Besides, the expression of COX-2 significantly increased in the reoxygenation group compared to the hypoxia group and the control group. The expression of PGE2 was higher than that in the hypoxia group and the control group. But there was no significant difference between the hypoxia group and the control group. Conclusions Hypoxia could influence the expression of COX-2 in lipopolysaccharide-Induced human periodontal ligament cells but does not affect the expression of PGE2. Reoxygenation could increase the expressions of COX-2 and PGE2. The hypoxia/reoxygenation condition might play an important role in periodontitis.

Objective To observe the effects of heat shock protein 70 (HSP70) induced by glutamine (Gln) on hyperthermia injury to human periodontal ligament cells.Methods The human periodontal ligament cells cultured in vitro were randomly divided into the following four groups:Control Group (Group C:normal human periodontal ligament cells),Gln Pretreatment Group (Group Gln:normal human periodontal ligament cells were added by Gln 15 mmol/L and cultured for 10 h),Severe Hyperthermia Group (Group SH:normal human periodontal ligament cells were cultured at 46 ℃ for 1 h),and Gln Pretreatment +Severe Hyperthermia Group (Group Gln+SH:after normal human periodontal ligament cells were added into Gln 15 mmol/L and cultured for 1 h,they were cultured at 46 ℃ for another hour).The expression of HSP70 was detected by Western Blot.Cell viability was measured using MTT and cytomorphology.Results Western Blot showed that there was higher expression of HSP70 in Group Gln and Group Gln+SH compared to Group C (P<0.05); MTT and cytomorphology indicated that cell viability was higher in Group Gln+SH than in Group SH (P<0.05).Conclusions Gln can induce higher expression of HSP70 in human periodontal ligament cells,thereby reducing hyperthermia injury.

Abstract： Objective To explore the better and mature technique of immediate implantation.Methods Animal experiments:Nine rural adult mongrel dogs were used in this study.Self-contrast was adopted.Mandibular third and fourth premolars were extracted bilaterally on all animals.Each premolar had two roots which were medial root and distal root.The implants with the same diameter as extraction sockets were placed into right mandibular third,fourth premolar distal extraction sockets and left mandibular third,and fourth premolar medial extraction sockets (Sim group); The implants with the smaller diameter than extraction sockets were placed into left mandibular third and fourth premolar distal extraction sockets.The space around the defects was filled with Bio-oss(Bio group).The dogs were killed randomly at 1st month,2nd months,3rd months after surgery.The tissue samples were stained with HE for histological examination and bone histomorphometric parameters were measured to quantify the change of new bone around titanium implants and to observe the changes of implant-bone interface.Results The success rate of Sim group was higher than that of Bio group.The bone plate of sim group was better in continuity,thicker and surrounded by a large number of osteoblasts.At 1st month after surgery,contact length fraction (CLF),bone ingrowth fraction (BIF) in Sim group have significantly increased compared with those in Bio group (P＜0.05).At 2nd,3rd months after surgery,contact length fraction (CLF),bone ingrowth fraction (BIF) in Sim group slightly increased compared with Bio group,but there was no significant difference between two groups (P＞0.05).Conclusions Using root-shaped implants with the same diameter as extraction sockets could accelerate osseointegration,and the CLF was higher than that in the defects around implants covered with Bio-oss.

Objective To investigate the effect of p38 signal pathway on the osteogenic differentiation of periodontal ligament cells in vitro.Methods Human periodontal ligament cells (PDLCs) was obtained from the third molar and cultured in vitro.Cells from the third passage were cultured in the osteogenic medium， and 10 nM SB203580(an inhibitor of the p38 signaling pathway) was added in the medium in experimental group for 4 weeks.Then the qPCR and Alizarin red S staining were applied to evaluate the osteogenic capability of PDLCs.Results Osteogenic induction could promote the phosphorylation of p38,and inhibition of the phosphorylation of p38 could down-regulate the expression of Runx2,ALP,OPN and OCN,and decrease the formation of calcium nodule,in PDLCs.Conclusions The p38 signal pathway plays a crucial role on the osteogenic differentiation of PDLCs in vitro.

Objective To verify the influence of different light intensities on the bond strength of fiber posts cemented with dual-cured resin cement.Methods 30 crownless human premolars were prepared.Fiber posts were inserted using dual-cured cement and were randomly divided into 3 groups(n=10):control group:no use of curing light source; low intensity group:the use of 600 MW/cm2 LED curing light intensity; high strength group:the use of 　　1 200 MW/cm2 LED curing light intensity.After one week,each root was sectioned transversally into three slices (cervical,middle and apical) and the bond strength of each section was determined using a push-out bond strength test.Results The bond strength:blank groupmiddle>apical.Conclusions When using a dual-cured cement,the bond strength of fiber post was influenced by the strength of curing light intensity.With the increase of curing light source intensity,the bond strength of fiber post also increased.

Objective To investigate the influences of aspirin on intra-socket clotting after extractions of tooth with periodontitis at different positions and to analyze the influencing factors.Methods 160 aspirin users (age:50-80 years old,course ＞ 2 week,dosage:100 mg/d) requiring an extraction of one tooth with severe periodontitis were enrolled.The selected teeth included 60 anterior teeth,40 premolars,60 molars and each kind contained 50% maxillary and 50% madibular cases.After pre-extraction Light Transmission Aggregometry (LTA) by Arachidonic Acid (AA) as the inducer,extractions were carried out in all cases without preoperative aspirin suspension and evaluations on clotting of all cases were performed postoperatively according to the Coagulation Classification Table (Class Ⅰ and Ⅱ indicated normal clotting,Class Ⅲ~Ⅴ indicated successively increasing bleeding).Comparisons on post-extraction clotting of all cases and on Platelet Aggregation Rates (PAgT) of cases with normal coagulation were implemented.Furthermore,analyses to anti-platelet effects of aspirin on extraction wounds of different tooth positions and search for potential factors influencing the effect of aspirin were conducted.Results (1) In anterior tooth area,premolar area and molar area,the percentage of cases showing normal clotting after an extraction of one maxillary tooth was 43%,15% and 10% respectively,and that of cases after an extraction of one mandibular tooth was 93%,30% and 20% accordingly.All cases of madibular central and lateral incisors (1, 2) were under Class Ⅰ and Ⅱ,cases under Class Ⅲ and Ⅳ appeared after extractions of a tooth of other positions.In addition,cases under Class Ⅴ were not observed.(2) In anterior tooth area,premolar area and molar area,the PAgT of cases with normal coagulation after an extraction of one maxillary tooth was (14.01±1.05)%,(15.27±0.62)%,(16.83±0.57)% with statistical difference (P=0.037) and that of cases after an extraction of one madibular tooth was (12.83±1.64)%,(13.92±0.87)%,(15.44±0.92)% with statistical difference (P=0.041).Additionally,the PAgTs of normal clotting cases after extractions of an anterior tooth,a premolar and a molar at maxillary dentition were higher than those for normal coagulation after extractions of a mandibular tooth at corresponding position (P=0.028,0.047,0.044 respectively).(3) In cases under Class Ⅲ and Ⅳ,the sclerotin of jaw bones and processus alveolaries adjacent to the sockets was loose with rich blood supply, and the areas of periodontal ligaments around the removed teeth were relatively large.Conclusions (1) Aspirin can exert an anti-coagulation effect on an extraction wound after removal of one tooth with severe periodontitis (except 1,2).(2) For both maxillary and mandibular dentitions,the PAgT required for normal clotting after extraction of an anterior tooth,a premolar and a molar rises successively,so the susceptibility to aspirin effect of extraction site of an anterior tooth,a premolar and a molar increases accordingly.The PAgTs for normal clotting after extractions of a maxillary tooth are higher than those for extractions of a mandibular tooth at corresponding position,so aspirin can lead to more influence on normal coagulation after removal of a maxillary tooth than that after extraction of a mandibular tooth.(3) The blood supply to jaw bones and processus alveolaries around the sockets,the areas of periodontal ligaments around extracted teeth can affect the post-extraction bleeding amount.Since extraction wounds with more bleeding require higher PAgT to achieve normal coagulation,the anti-platelet effects of aspirin on the surgical sites become more obvious.

Objective To explore the expression levels of cyto/chemokines in the gingival crevicular fluid (GCF) of type Ⅱ diabetic mellitus subjects with chronic periodontitis compared with those with simple periodontitis.Methods Fifty-two type Ⅱ diabetic mellitus subjects and forty non-diabetic mellitus subjects with chronic periodontitis were enrolled in this study.The levels of 14 cyto/chemokines were measured in the GCF of healthy and diseased sites of the diabetic and non-diabetic mellitus subjects with chronic periodontitis using Luminex FLEXMAP3D plate reader and Human Cytokine/Chemokine kits.Results The concentrations of eotaxin,macrophage inflammatory protein-1α,granulocyte-macrophage colony-stimulating factor,interleukin (IL)-6,tumour necrosis factor-α and IL-12 were higher at healthy and diseased sites of diabetic mellitus than non-diabetic mellitus subjects.Conclusions Type Ⅱ diabetes mellitus modulated the levels of several cyto/chemokines at both healthy and diseased periodontal sites.It may be a facilitating factor to periodontal disease.

Objective To study the clinical therapeutic effects of plane plate on Class Ⅱ division 2 malocclusion patients with temporomandibular disorders (TMD).Methods 20 outpatients who had Class Ⅱ division 2 malocclusion with temporomandibular joint disorders from January 2013 to December 2014 at Jiangsu Provincial Stomatological Hospital of Orthodontics and TMJ Branch were selected in this study.All were treated by the plane plates and used United States Myotronics K7 (Neuromuscular Dentistry analysis system) was used to record their changes of condylar trajectory and vibration frequency before and after using the flat-screen guide appliance.Results ①After being treated by plane plate,maximum mouth opening,protrusion and lateral movement all had little changes compared with the previous treatment (P> 0.05).②The style of mouth opening was changed after treatment (P<0.05).③Joint vibrations were statistically changed compared with those before treatment (P<0.05).Conclusions The plane plant can lead to open bite on deep overbite patients,improve jaw movement patterns,and relieve related symptoms of temporomandibular diseases,thus providing guidance for clinical treatment.

Objective To study the effect of different chairside heat bleaching times on the healthy central upper incisors.Methods The subjects were treated with chairside heat bleaching for three times (an interval of one day),45 minutes each time.Color parameters of the six healthy central upper incisors before and after each time of bleaching by Wy10 were determined using a dental colorimeter and a VITA classical shade guide.The statistical analysis of the results was performed using paired t-test.Results Paired t-test showed that L* and W(Lab)parameters of all the central upper incisors increased(P<0.05) and b* demonstrated a negative trend(P<0.05),which meant that whiteness and brightness of the teeth improved and the incisors exhibited a blue-trend .The margin grewwith the increase in the number of operation times.Color difference after each time of bleaching could be identified by the human eye(ΔE>1.7).Conclusions The increase in the number of operation times leads to the improvement of the heat bleaching effect.

Objective To study and evaluate the short-term restorative effects of IPS e.max CAD ceramic crown.Methods 469 patients with 542 restorations were selected and the satisfactory degree of the patients was investigated.The restorative effect was evaluated after 3-12 months.Result The satisfactory rate of IPS e.max CAD full ceramic restorations was 97.2%，without porcelain fracture,loss of crown or abutment broken.Conclusion The short-term clinical behavior of IPS e.max CAD all ceramic restorations is encouraging.

Objective To evaluate the efficiency of micro-implant anchorage (MIA) for the treatment of scissors bite on second molars.Methods Nine patients (7 males and 2 females with a mean age of 22.5 years old) of scissors bite on second molars were treated with MIA.CBCT were used to measure and analyze the Dicom data before and after treatment.Results With MIA,the scissors bite on second molars were corrected for a mean course of 4 months.U7j-the sagittal plane distance decreased significantly,and L7j-the sagittal plane distance increased significantly (P<0.05),suggesting the restoration of dental arch width of molars; U7-SN increased significantly,and L7-SN decreased significantly (P<0.05),suggesting that the molar′s axis was restored to normal level.Conclusions MIA could be used as an efficient method to correct scissors bite on second molars; both lock tooth buccal lingual and height abnormalities could be corrected.The course of treatment was short and the efficiency was good.

Abstract: Objective To make a correlation analysis of crown widths between premolar,cuspid,and other teeth groups in malocclusion population.Methods Pre-treatment models of 382 patients (187 males,195 females,aged from 14 to 25 years) were selected from the records of the Orthodontic Department,Stomatology Hospital of Jiangsu Province.According to the Angle′s classification,the subjects were divided into 4 groups:Class I,Class Ⅱ division 1,Class Ⅱ division 2,and Class Ⅲ.The mesiodistal dimensions of teeth were measured using callipers (accurate to 0.02 mm).Then crown width correlation was analyzed and the prediction equation was set up.Results The correlation coefficients had significantly statistical difference.Equations predicting summation of mesiodistal crown-widths of upper and lower unerupted canine and premolars in male and female were established respectively.The male:U3U4U5=0.270X+3.504(r2=0.5821),L3L4L5=0.272X+2.390(r2=0.5977).The female:U3U4U5=0.221X+6.884(r2=0.4951),L3L4L5=0.230X+5.173(r2=0.5000) (X represents the summation of the mesiodistal crown widths of upper and lower central incisors and first molars).Conclusions The equations predicting summation established by this research were more precise than Moyers regression scheme,and were not influenced by the Angle′s classification.

Objective To evaluate the clinical effects of maxillary protraction with repetitive rapid expansion and constriction or maxillary protraction with rapid expansion only on treating skeletal class III patients with maxillary dysplasia.Methods 34 cases of skeletal class III children with maxillary dysplasia were randomly divided into two groups:the observation group and the control group.The observation group contained 17 cases treated with maxillary repetitive rapid expansion and constriction combined with maxillary protraction,which were further divided into the low angle group (12 cases) and the high angle group (10 cases).The control group contained 17 cases treated with simple rapid maxillary expansion combined with maxillary protraction.Cephalometric radiographs of all cases were taken before and after treatment,and data were given projection measurement analysis.Results Anterior displacement of maxilla,as well as downward and backward rotation of mandible was found after maxillary protraction in both groups.To compare the two groups:in the observation group,A-NP and A-Y distance increased by 2.50 mm and 3.47 mm respectively,which were greater than 1.37 mm and 2.05 mm in the control group.Conclusions Maxillary repetitive rapid expansion and constriction combined with maxillary protraction can obtain larger amount of anterior displacement in maxilla than simple rapid expansion combined with maxillary protraction.Besides,the former had more effect on the low angle patients.

Objective To investigate the effects of biofeedback in treating patients with masticatory spasm using electromyograph.Methods Ten cases were chosen from the patients whose final diagnosis was masticatory spasm.The cases were given EMG biofeedback treatments and psychological supports under the guidance of electromyograph.Then the cases were measured and analyzed by electromyograph before and after the occlusal adjustment.The clinical effect of biofeedback was evaluated through the clinical examination such as occlusal and EMG activity of masticatory muscles,the value of Fricton′s Craniomandibular Index,the value of visual analogue scale (VAS).The levels of psychosocial incapacity of the cases were evaluated through the value of the Symptom Checklist 90(SCL-90).Results Compared to pre-treatment,the value of patient′s CMI and the value of patient′s VAS decreased obviously with statistical difference(P<0.05).The value of patient′s SCL-90 decreased on somatization and hostility with statistical difference (P<0.05).Conclusions EMG biofeedback treatment and psychological supports under the guidance of electromyograph were effective to treat patients with masticatory spasm.

Objective To discuss the effect of applying piezosurgery in the alveoloplasty.Methods 80 cases of patients who need alveoloplasty and meet our criterion were selected，which were randomized equally into treatment group (n=40)receiving Piezosurgery and control group(n=40) receiving traditional method respectively,and then the clinical data of two groups were retrospectively analyzed.Results The heart rate，mean arterial pressure，pain score，operation time and satisfaction of the treatment group were all significantly better than those of the control group.Conclusions Compared with traditional method of alveoloplasty，piezosurgery has such advantages as high efficiency，slight trauma，low psychological impact on patients，which may enjoy broad development prospect in alveoloplasty．

Objective To evaluate the effects of the three-dimensional (3D) CT-based rapid prototyping technique on clinical mandibular reconstruction.Methods Seven patients suffering from mandibular lesion were selected,and surgery was designed preoperatively on the 3-D model which was created by using the rapid prototyping technique and based on the 3-D CT scanning data.Guided by the preoperative design,the mandibular lesion was excised and the following bone defect was immediately reconstructed with a vascularized iliac osteomyocutaneous flap or a vascularized fibular flap,or just a simple reconstructive titanium plate.The patients were then followed up regularly.Results The mandibular defect was reconstructed with the vascularized iliac flap in three patients,with the vascularized fibular flap in three patients and with a simple titanium plate in one patient.The patients had been followed up for 6-24 months.The contour of the reconstructed mandible was symmetrical in all patients.No malocclusion or limitation of mouth opening was found.The postoperative functions of mastication and speech were satisfactory in all patients.Conclusions Reconstruction of mandibular defect can benefit from the application of the 3D CT-based rapid prototyping technique.

Objective To investigate the application value of cyst plugs in the marsupialization of jaw bone cysts.Methods Subjects were 122 patients with gigantic bone cysts of the jaws and cysts in the mixed dentition since 2008,among whom one patient was with multiple cysts.All patients underwent the marsupialization,and then 125 pieces of cyst plugs were made.Results Cyst cavities of 100 patients were closed in 1-2 years,including 23 children of 9-12 years old.22 patients had a second operation because one small cyst cavity was left after the surgery,but no cysts recurred during 2 years′ follow-up.The healing time in the mandible was shorter than that of the maxilla.Normal eruption of permanent teeth was observed for patients with mixed dentition,and the swelling face returned to normal.Conclusions Cyst plugs can prevent food from flowing into cyst cavities,and guarantee the drainage of cyst fluid.

Objective To evaluate the fracture resistance of CAD/CAM zirconia all-ceramic crowns.Methods 284 all-ceramic crowns were fabricated for 189 patients.226 restorations of 156 patients were clinically followed up for 2.5-5.5 years.The site of crown,fracture or breakage,loose or dislodgement were observed.Results The fracture rate was 0.9% at 1 year after the insertion date,2.1% after two years,3.3% after three years,7.1% after four years.Overall the fracture rate was 9.7% with 226 restorations.Base crown fracture took place in two cases.A statistically significant difference was found for fractures when the opposing dentition of natural teeth and fixed restorations were compared (P=0.034).The fractures were most commonly noted when the opposing dentition was a fixed metal ceramic or other ceramic restorations.Conclusions The fracture resistance of CAD/CAM zirconia all-ceramic crowns was acceptable clinically and it can be a preferred esthetic restoration.

Chronic periodontitis is a kind of chronic inflammatory disease characterized by periodontal tissue damage.The ultimate therapeutic aim of periodontal disease is to obtain periodontal tissue regeneration.The local inflammatory microenvironment caused by periodontal disease not only leads to periodontal tissue damage,but also affects the process of periodontal regeneration.For example,it can affect the proliferation and differentiation of periodontal ligament stem cells and stifle the function of growth factors.This review discussed the effects of the inflammatory microenvironment on the regeneration of periodontal tissue.

Pain is a symptom of temporomandibular disorders.It is also the reason for most people to treat temporomandibular disorders.Low-level laser is more and more widely applied in the field of dentistry,and is often used in the clinical treatment of temporomandibular joint pain for anti-inflammation and pain relief.In this paper,the mechanisms of the low-level laser therapy in treatment of temporomandibular disorders pain are summarized.Understanding its mechanism is of great significance for the clinical application of low-level laser in treating temporomandibular disorders.

Useful information can be obtained from trace elements in the teeth,such as human nutrition,environmental pollution,exposure to toxic metals and disease information.Inductively coupled plasma mass spectrometry (ICP-MS) is becoming the main analytical technique for determining the trace elements in human tooth enamel,with the advantages of quasi-simultaneous multi-element detection,excellent detection limits,wide linear detection range,isotopic analyses and ratio information,efficient ionization,simple interpretation of mass spectra,etc.In this paper,research progresses for determination of trace elements and isotope ratios in human tooth enamel by inductively coupled plasma mass spectrometry (ICP-MS) are summarized.At the end of this paper,the promising future research directions are proposed.

Pain-pressure threshold (PPT) has been used as a quantitative sensory test in orofacial pain study.It plays a significant role in revealing the mechanism of pain,the procedure of disease and the different outcomes of different treatments.This article reviewed the research progress and limitations of orofacial pain study using PPT.