In Vitro And Clinical Evaluation Of Subgingival Air-polishing

Background:Periodontitis is a chronic infectious disease in the supporting tissue of tooth caused by micro-organisms in the dental plaque,resulting in periodontal tissue inflammation,periodontal pocket formation and alveolar bone absorption,which may eventually lead to tooth loose and extraction.Dental plaque is the initiating factor of periodontal disease, and subgingival plaque is the survival microecological environment of periodontal pathogens,it exists on the root surface in the periodontal pocket and the gap of periodontal pocket,which is most closely related with periodontal tissue.First goal of the treatment of periodontitis is plaque control and eliminate inflammation,then to restore the physiological form and function of periodontal tissues,and to prevent recurrence.And the most central part of periodontal treatment is plaque control.The main way of plaque control is mechanical scaling and root planing. Through subgingival scaling and root planing to remove subgingival plaque and calculus,resulting in the improvement of the microecological environment of periodontal pocket is the important step in the treatment of severe chronic periodontitis.Subgingival scaling and root planning is the important step in the treatment of severe chronic periodontitis by improving the microecological environment of periodontal pocket by removing the subgingival plaque and calculus.However,the complete removal of subgingival calculus and plaque is not possible,After scaling and root planing,the amount of the residual calculus is up to 3%-80% depending on the performer' s expertise.At the same time,researches in recent years have shown that in the course of periodontal treatment, either hand or machine equipment,will lead to loss of root hard tissue. With regard to ultrasound equipment,the greater power and longer time of operation,the bigger the trauma to the tooth surface and more damage to the hard tissue of teeth.Particularly when dentin exposing caused by cementum exfoliation,it' s easy to lead to dentin hypersensitivity or the occurrence of root caries.Bacteria even invade the dental pulp through the exposed dentinal tubules,then cause pulpitis.Therefore, the change of root surface structure such as rough,irregular,cracks, pits,etc.,providing a convenient conditions to forming new plaque and calculus remaining,self-cleaning effect is not conducive to the clean-up. Because periodontal maintenance is conducted on a regular basis,even if only a small amount of cementum loss by curettage each time,the cumulative effect will cause serious injury on the root surface,which affected the maintaining efficacy of periodontitis treatment.In such situation,how to remove the subgingival calculus,plaque and the smear layer efficiently and thoroughly as well as minimize the damage to root surface,then providing a smooth,clean root surface,becomes a new research direction.Air polishing on tooth surface after scaling can effectively remove plaque,increase the smoothness of tooth surface and slow down the deposition of plaque and pigment.But traditional methods such as rubber cup polishing can not be located on the subgingival root surfaces. Blasting technology can remove the plaque in periodontal space,but traditional methods always using abrasive powder such as sodium bicarbonate,is easy to cause damage on the root surface and periodontal soft tissue.Significant root substance removal may occur when the spray is directed towards denuded root surfaces or dentin;this is corroborated by various other studies aimed at quantifying root substance loss due to air polishing,where resulting defect depths of up to 856μm after 30s instrumentation time have been reported.Polishing on the root surface in periodontal pocket has been to a problem.In recent years, with the development of new equipment and materials,the using of low wear polishing material and small spray nozzle make subgingival air polishing become possible.Subgingival polishing using new technologies and materials make air polishing break through the limitations,so it can be used deeply into the periodontal pocket on root surface. Subgingival polishing can reduce the residual plaque and biofilm,make the root surface cleaner and smoother,and slow down the deposition of plaque and calculus,then to consolidate the curative effect of periodontal treatment.Glycine particle is a water-soluble low wear material,the new type of blasting powder using glycine as the main raw material has many advantages such as smooth,small size,low wear and water-soluble.EMS Company' s AIR-FLOW MASTER system can use the new type powder labeled Perio-Flow to do air polishing in periodontal pocket,in addition to traditional supragingival air polishing treatment.Flemmig,TF and Petersilka,GJ et al shows that the new type of polishing material mainly composed of glycine particles cause little damage on subgingival root surface,histological examination also proved that there is no obvious injury on soft tissue,so that it can be used to carry out root surface polishing.Foreign scholars study the effect of plaque removing through the technology of plaque staining.Results show that air polishing using glycine powder on each tooth surface for 5s,have significant effect in the sites of probing depth of less than or equal to 3mm.Bacteriological study also proved that both in buccal and lingual sites,glycine powder air polishing is more effective in subgingival plaque reduction than the traditional manual way.The study in interdental site shows the same result.This new technology contributes to the treatment of periodontal disease;it is expected to become a new additional way to periodontal treatment.There is no report on this new material and technology in China at present.Objective:Air polishing using the new materials of Perio-Flow powder on periodontal involved teeth following periodontal treatment,then studies the root surface character after treatment by scanning electron microscopy.Photographs were taking to do the morphological observation so as to judge whether the technology will damage the root surface. Detected the root surface roughness changes by profilometer,then Statistic and analysis for data do determine whether the new technology make the root surface smooth and flat.Produce a randomized clinical trial on clinical probing depth,to analysis whether the new technology will help reduce the inflammation of periodontal tissue and promote tissue healing,so as to assess the effect of new subgingival polishing technology for the treatment of chronic periodontitis.Provide experimental support for this new technology in the clinical applications.Methods:PartⅠ:Comparison on root surface roughness after subgingival polishing.1.Samples collection:10 single root teeth suffering from severe chronic periodontitis were recruited for the study.Patients have to be in good general health,18-60 years old,without conta-gious diseases,pregnancy or lactation, systemic diseases such as neutropenia,angranulocytosis,diabetes or bleeding disorders.Selected teeth should meet the following requirements:①suffering from serious chronic periodontitis;②probing depth＞4mm in interdental site;③did not undergone periodontal treatment(scaling,root planing) for at last 6 months;④without caries or filling,restoration on adjacent surface;⑤no acute inflammation.2.Sample treatment:Root planing was operated on the recruited teeth a week after supragingival scaling,until root surface was smooth and hard checked by probe inspection.Treatment was performed using the same ultrasound equipment and parameter set,all operation was performed by the same physician.After the basic treatment,10 teeth of 20 proximal root surfaces were randomly divided into 2 groups.Subgingival air polishing was performed with the new PERIO-FLOW powder on the root surface in test group;spraying water only on the surface in control group as controls. Do clinical observation and record whether there is pain or other discomfort during the treatment.The location of the gingival margin was marked on the investigational root surface under local anesthesia with a round bur.Teeth were extracted immediately after operation,avoiding any contact with the root surface.Put the teeth under running water to remove the blood then fixed in formalin.Teeth crown was removed by sand chip under water cooling.Divide the root into two halves of mesial and distal along the long axis,and then rinse the sample into sterile saline water,followed by gradient ethanol dehydration,critical point drying.3.Data analysis:Samples will be placed in the optical profilometer using the same set of parameters to measured surface roughness then get the Ra(average roughness) value.Input the data into SPSS13.0 statistical software for analysis of paired T test.PartⅡ:Root surface observation after subgingival air polishing.1.Sample collection:criteria for selection are same to experiment(1), six teeth were selected.2.Sample treatment:clinical procedure is same to experiment(1).3.Data Analysis:Observe the root surface by scanning electron microscope,take image to study.PartⅢ:Clinical trial for the effect of subgingival air polishing.1.Case selection:Patients with moderate or severe chronic periodontitis were recruited in the study.Patients had a minimum of 20 teeth,were 18-65 years old; and in good general health.Patients presenting with one or more of the following diseases or conditions were excluded from the study:contagious diseases,pregnancy or lactation,systemic diseases such as neutropenia, angranulocytosis,diabetes or bleeding disorders.Patients were also excluded if radiotherapy or chemotherapy was performed before or during the study period or if there was a need for antibiotic coverage. Furthermore,the performance of any kind of subgingival instrumentation or the use of antibiotics within the 3 months preceding the study were criteria for exclusion.At least one tooth with probing depth at 4-6 mm in each quadrant.2.Clinical procedure:Recruitment of the patients and periodontal examination with measurement of 6 sites per tooth using manual periodontal probes was done 1 week after supragingival scaling to study the baseline.Perform subgingival air polishing on select group one week after initial periodontal treatment. The dentition was divided in terms of a split mouth design into two quadrants assigned to test treatment using low abrasive air polishing or positive control treatment(hand instrumentation).Test treatment was performed using the new glycine powder in a standard air-polishing unit, which was set to a medium water and powder setting.Control treatment was performed by the same polishing way without the new glycine powder. Return visits were performed in 1 month,3 months and 6 months after treatment.Record the periodontal examination every time.3.Data analysis:The data of periodontal examination were input into SPSS13.0 statistical software,analysis by repeated measures.Results:PartⅠ:Comparison on root surface roughness after subgingival polishing. The samples after treatment were measured by optical profilometer,the Ra value data of surface roughness were statistical analysis by SPSS13.0 software.Perform paired t test,t = 2.546,P = 0.031,(n = 20),show that the periodontal pocket for polishing,the roughness between the two groups have significant difference.PartⅡ:Root surface observation after subgingival air polishing. Control group:The roots of control group sometimes revealed grooves and cavitations of the cementum.Under higher magnification,irregularities and defects were observed in some areas.Plaque and remained calculus could be seen in many pictures,many areas were covered with a smear layer. Test group:The roots treated with subgingival air polishing had a clean, smooth surface under low magnification.Under higher magnification,the dome-shaped cementum structure was observed in some regions,although some calculus remained.PartⅢ:Clinical trial for the effect of subgingival air polishing. The baseline data were analyzed by independent t test,F=2.190,P= 0.139,difference between the two groups is not significant.Analyzing the data using repeat measurement test,F=2.263,P=0.133,means that the change of pocket probing depth is not significant between test and control groups.Conclusion:1.The use of the new glycine material Perio-Flow for subgingival air polishing for periodontitis patients did not cause obvious damage on periodontal soft tissue.There was no pain or other complications appeared during the experiment caused by air polishing;2.There was significant difference in root surface roughness between the test group and control group.The root surfaces treated after subgingival air polishing were smoother and flat; 3.Scanning electron microscope study showed that subgingival air polishing could reduce the residual plaque and smear layer on root surface after initial periodontal treatment,and not make significant damage on the root surface;4.Current study can not prove that subgingival air polishing can have significant improvement in clinical healing effect.