The Three-dimensional Cephalometry Of Occlusal Vertical Dimension&Polyacrylic Acid/strontium/silica Component Applied In Dentin Hypersensitivity

[Part 1]Background and objectsBecause of the decrease of clinical crown heights,the full mouth rehabilitation patients owning to the advanced tooth surface loss(TSL)sometimes have difficulties as the lack of restoration space.Traditionally,endodontics or crown lengthening therapies are suggested to make extra space rather than increasing the oral vertical dimension(OVD).The OVD is defined as the distance between two selected anatomical or marked points.Although it has been widely accepted as one of the decisive considerations in oral rehabilitation,whether an increased OVD can be conserved continues to be debated.In 1930s,some scholars believed that occlusal adjustment including bite raising may introduce the temporomandibular joint disorder(TMD).Thus,the OVD increasing was a dangerous and an improper therapy.Whereas in 1990s,as the development of evidence based medicine and clinical reseach,researchers turned to believe that there is no strong evidence proving the link between the occlusal adjustment and TMD.Nowadays,the TMD is thought to be a kind of disease owning to the disorder of the occlusal-muscle-TMJ system.The fluctuating hormones and social-psychological factors are contributing factors.Apart from the concern about TMJ,another consideration is the reliability of OVD increasing.Some investigators believe that because of alveolar bone remodeling,the OVD is stably sustained throughout life.Some anatomy studies illustrated that there exists the compensation for the vertical height loss of tooth wear.The compensation may come from three aspects including tooth eruption,alveolar bone and mandible relocation.As for the tooth,several X-ray studies found that the tooth erupting trend continues throughout the life.It has been explained as the accumulation of apical cementum push the tooth erupting until approaching to antagonists.In advanced TSL,the evident shortness in clinic crowns indicates that the erupting has limitation.The relocation of the mandible may also balance the rapid reduce in OVD as the anterior protrusion of mandible is usually detected when the molars are lost.As to the alveolar bone,no evidence shows the correspondence growth with the erupting tooth.Results from some studies indicated that the height of the alveolar process remains constant.Thus,under the situation of TSL,tooth eruption and relocation of mandible may counterbalance the OVD loss to some extence.When it comes to the OVD increasing,the reaction in the tooth,mandible or alveolar bone is an importance issue to explore.Although,whether the increased OVD return to the bases is closely connected with the application of bite raising therapy in clinical practice,to date,there is still no conclusive evidence supporting or refuting the constant OVD theory,possibly due to difficulty in sample collection and bone marking problems.Benefiting from current cone-beam computerized tomography(CBCT)and three-dimensional(3D)cephalometry,detailed bone observation can be performed noniNvasively.In the present study,a new bone marked OVD evaluation system has been proposed.This evaluation system measures the OVD as a whole(Anterior lower facial heights ALFHs)and as separating parts(Alveolar process heights APHs,Occlusal dentition height ODH and condyle space CS).The analyses of cone-beam computerized tomography(CBCT)before and after bite raising were performed to study OVD changes in included 6 oral rehabilitation patients.This study provided a new reliable OVD evaluation system and provided preliminary results to resolve associated debates and develop guidelines for clinical practice.Part 1 The 3D cephalometry of oral vertical dimension after bite raisingExp.l The design of 3D cephalometry evaluation system and the intra-observer reliability test[Materials and Methods]CBCT images were obtained using a high-resolution Newtom(QR s.r.l.Silvestrini,2037135 Verona,Italy)with a 15 cm × 15 cm field of view,110 kV,2.6 mA and scanning time of 3.6 s.Both the axial pitch and thickness of each image were 0.30 mm.The CBCT images were then transformed into DICOM forms with a matrix setting of 512 × 512 pixels and were analyzed by SIM/Plant O&O(Materialize,Leuven,Belgium).To verify the reliability of the methods used to obtain the ALFH and APH meas-urements,three patients'CBCT images were measured by three operators.The intra-observer reliability(ICC)was evaluated for the three operators'measurements.Two-way ANOVA without replication was applied to calculate the ICC for each item and site.[Results]This evaluation system measures were designed into two parts:the OVD as a whole(Anterior lower facial heights ALFHs and Vertical facial patterns VFP)and as separating parts(Alveolar process heights APHs,Occlusal dentition height ODH and condyle space CS).3D frankfort plane and mandible plane had been chosed as the reference planes.The intra-observer reliability(ICC)was high for all 60 ALFHs and APHs,with an ICC ranging from 0.936 to 0.999 and a mean ICC of 0.993.Exp.2 The measurements of the include data[Materials and Methods]The including criteria and excluding criteria have been settled.Combining with the medical history,cases were selected under certain critarna.The ALFHs,APHs,VFP and CS are valued.Paired t-tests were performed to compare the mean differences in items before(T0)and after the OVD increase(T2)in the same patient.All statistical analyses were performed with SPSS 22.0 for Windows software(version 22,SPSS,Chicago,IL).Statistical significance was set at a two-tailed P value of 0.05.Three time points were used in this study:T0(before the treatment),T1(immediately after treatment)and T2(the follow-up).To observe the variations before(T0)and after the increase in OVD(T2),3D reconstructions and 2D cephalometry derived from CBCT images were performed.The CBCT images immediately after the OVD increase(T1)were not taken because of the unnecessary radiation exposure.[Results]A total of six patients,including three males and three females with an average age of 51.8 years,were enrolled.The findings indicated that the increased OVD did not relapse to baseline and was sufficiently tolerated,with mostly constant APHs and an altered ODH after two years of observation in the six patients.?Conclusions]1.The methods of measuring parameters on CBCT images were found to be highly reliable.2.Overall,the results indicated that an increased OVD did not relapse to the baseline,and that the increased OVD was largely maintained.Additionally,the ODH was compressed partially and APHs remained constant over the two years of observation in the six patients,suggesting that the increase in the OVD was reliable during the observation period.This study also provides supports for the use of bite raising in oral rehabilitation,although further in-depth studies are needed.[Part 2]Background and purposeDentin hypersensitivity(DH)is a kind of common oral health problem owning to the exposed dentin tubular because of pathological or iatrogenic problems.The expose of dentin surface may result in pain and secondary infections,carries or pulpitis,for example.To dealing with the DH,several agents have been synthesized to cover dentinal tubules,including the ions/salts with or without organics,dentin sealers and lasers.In majority of the therapies,dentin tubular occluding is design to be achieved by the precipitation of crystallization precursors or remineralization of exposed apatite seed crystallites.To introduce deep remineralization within the dentin tubular,the nucleation process is required to be stable in the fluctuate oral fluids.In this part 2 exploring the mineralization materials,a new PAA/strontium/silica component applying in DH has been synthesized.This material mimicking the precipitation of nature co-accumulation of carbonates and silica,occluding the dentin tubular by strontium carbonates and silica through simple methods.It has been tested that the component can occluding the tubular in the depth of 7-50?m with the primary pH of 8.5,9.5,10.5 and 11.5.Meanwhile,in the 4 pH value groups,all of them presented acceptable antibacterial potential with(F.E.)and remineralization abilities in artificial saliva.Part 2 PAA/strontium/silica components applied in dentin hypersensitivityExp.1 Several ways to synthesized the strontium carbonates and the compare of the occluding ability[Materials and methods]By using different methods synthesized the strontium carbonates,compares have been made observing the occluding abilities.Group 1,control group:the dentin disks after immersing in distilled water;Group PAAwt2000/Sr:1%PAAwt2000 and SrCol2.6H2O(pH11.5);Group PAAwt2000/Sr/Si:1%PAAwt2000,SrCl2.6H-20 and silica(pH11.5);Group PAAwt5000/Sr/Si:1%PAAwt2000,SrCl2.6H2O and silica(pH11.5);Group nano carbonate strontium:SrCl2.6H2O mixing in the carbonate solutions with alcohol in room temperature for 24h,after the synthetization,the solution was applied in the dentin surfaces.6 disks in every group immersing in experiment solutions for 3 days,then the surfaces and longitude surfaces were observed under FESEM.[Results]In the longitude surface,the occluding in depth were acceptable in Group PAAwt2000/Sr/Si and Group PAAwt5000/Sr/Si.In Group PAAwt2000/Sr/Si,the depth was about 20-30?m;while the wall of the dentin tubulars presented cystals in the depth of about 40-50?m.Exp.2 The physicochemical properties of PAA/strontium/silica components[Materials and methods]Groups had been settled as Group control,Group A:pH8.5,Group B:pH9.5,Group C:pH10.5,and Group:D pH11.5.Microsturure of the deposited surfaces of the components was observed by FESEM,and TEM.After been air-dried,the surfaces were checked by micro-Ramam,ATR-FTIR,FTIR and EDS.The components collected in the solution were analyzed by FTIR and XRD.[Results]FESEM showed that even components had been deposited on the surface.In the TEM displayed the crystallizations were cover by low transmitted substance with small sizes.The ATR-FTIR,FTIR,XRD and EDS had showed that the components were the co-precipated carbonate and silica.The silica net was presented in the form of Q1 and Q2.Exp.3 The occluding of PAA/strontium/silica components in variable pH regions[Materials and methods]Groups had been settled as Group control,Group A pH8.5,Group B pH9.5,Group C pH10.5,and Group D pH11.5.Acid challenge had been proceeded.The un-acid challenged and acid challenged groups had been observed in the surface and longitude facades.[Results]In both the acid and un-acid challenged groups,the tubular structures were cover with materials,and in the longitude views,all the experiment groups displayed the occluding depth of 7-40?m.Exp.4 The antibacterial and remineralization properties of PAA/strontium/silica components[Materials and methods]Live/Dead staining assay was applied to observe the bacterial potential,and the number of the bacterial cell were counted on the samples.The sample disks had been immersed in the artificial saliva for 7 days,in day 1,3,7,the samples were tested by Raman.[Results]All the A,B,C,and D groups had showed antibacterial potential compared with control group.The remineralization ability had been displayed in all pH groups.