| In clinical practice,periodontal ultrasound treatment has become an important part of daily periodontal treatment.In the use of the ultrasonic instruments,the top of the working top cannot contact the root surface directly.However,due to the limitation of the contact area,sometimes the top inevitably contact the root surface,while the specific damage caused by the top to the root surface is rarely studied;In ultrasonic subgingival scaling,sediments were removed by high-frequency oscillation of the working tip.The magnitude of oscillating forces on different working surfaces(front,back and side)was different,and the degree of damage to the root surface was also different.At present,there was no research on the damage of the root surface in different working surfaces of the working tip.Therefore,this experiment used two kinds of piezoelectric instruments of the straight-type thin-diameter working tip,the top and the side of the working tip to scaling the periodontitis teeth,and the different working face to scaling the healthy root surface.To explore the damage of different working end and working face of root surface in order to provide reference for clinic.Experiment 1: The effects of the side and the top of working tip on root surface damage after scaling for the tooth of periodontitis in vitro Objective :Two kinds of piezoelectric ceramic ultrasonic instruments with the straight-type thindiameter working tip were used,the side of working tip(correct clinical operation)and the top of working tip(wrong clinical operation)to scaling periodontitis teeth,and the damage of the root surface were compared.Methods:Sixteen teeth with periodontitis were selected,and the proximal and distal root surfaces were the scaling area.They were randomly divided into the side group and the top group,according to the different ultrasonic instruments,they were randomly divided into groups A and B,Four healthy teeth were selected as control group;The side group and the top group used the side and top of the working tip,respectively.The scaling methods were performed from the bottom of the enamel cementum boundary to 1/3 of the root tip,from the crown side to the root side,The end of the operation was to visually observe no calculus in the treatment area,and the root surface was hard and smooth with a probe.The control group was observed without periodontal treatment.The tooth roots 2mm below the cementoenamel junction were cut into small pieces(5mm×4mm×1mm).The root surface structure was observed by Stereo Microscope,and the roughness(Sa)of the root surface was measured by LSCM.and the root surface ultra-microstructure was observed by SEM.Results : 1.The root surface roughness(LSCM)The side group: instrument A(0.646±0.068)> instrument B(0.608±0.082)> healthy group(0.533±0.036),but the difference was not statistically significant(P > 0.05).The top group: both instrument A(0.995±0.229)and instrument B(0.922±0.151)were larger than that in the healthy group(0.533±0.036),and the difference was statistically significant(P < 0.001).instrument A(0.995±0.229)> instrument B(0.922±0.151),but the difference was not statistically significant(P > 0.05).Comparison between the side and the top group: the root surface roughness of the two instruments of the top group was greater than that of the side group [instrument A:(0.646±0.068)vs(0.995±0.229),and instrument B:(0.608±0.082)vs(0.922±0.151)],and the difference was statistically significant(P < 0.001).2.The root surface structureStereo Microscopes: The side group of the instrument A and B were similar to the healthy tooth control group and the root surface was flat and frosted,the root surface of the top group was uneven,and the roughness was obvious.SEM:Healthy root surface was flat and smooth,showing normal fish-scale cementum morphology and root fiber.The roots surface of the side group of the instrument A and B were relatively flat,with obvious smear layer,work marks and a small amount of defects of cementum was observed in instrument B.The roots surface of the top group of the instrument A and B were uneven,with obvious smear layer,pit-like defects of cementum of irregular edges,instrument A was larger and deeper than B,and there were a lot of debris at the pits,and dentinal tubules exposure.Conclusions: 1 There was no statistically significant difference between the roughness of root surface and healthy teeth after scaling on the side of working tip of the two ultrasonic instruments,and the root surface structure was similar to that of healthy teeth,with less damage to the root surface.the top of working tip can significantly increase the roughness of the root surface,making the root surface uneven and the cementum pit-like defects,causing serious damage to the root surface.2 Clinically,when using the ultrasonic instruments for subgingival scaling,the side of the working tip should be standardized used and the top of the working tip should prohibit direct contact of the root surface to avoid serious damage to the root surface.Experiment 2: The effects of different working surfaces of working tip on the root surface of healthy teeth Objective :Two kinds of piezoelectric ceramic ultrasonic instruments with the straight-type thindiameter working tip were used,the different working surfaces were scraped 20 times with the root surface of the healthy teeth,and the damage of the root surface were compared.Methods:Three healthy teeth were selected,and the front,back and side of the ultrasonic working tip were used respectively.The root surface of buccal-lingual side was the scaling area,which was divided into crown side and root side.The buccal side crown uses instrument A,the root side uses instrument B,and the lingual side is reversed;the front,back,and side groups used the front,back,and side of the working tip,respectively.The effective area of the working tip reciprocated 20 times in parallel with the mesial and distal directions of the root surface,and the movement range was 4-5 mm.All the test areas of the tooth roots were cut into small pieces(4 mm × 3 mm × 1 mm),and the root surface ultra-microstructure was observed by SEM.Results :SEM:The cementum defects was visible in the root surface of all groups,and the degree of defects in the front and back groups was similar,and micro-cracks and a large number of dentinal tubules were exposed.The side group was smaller than the front group and the back group,only a small amount of dentin tubules were exposed,and the cementum defects of each instrument B were larger than the instrument A;Roughness: The front group and the back group were similar,the side group was smaller than the front group and the back group,and the roughness of each instrument A was greater than that of the instrument B.Conclusion:The front,back and side of the working tip of the two ultrasonic instruments showed the cementum defects and root surface roughness increased after 20 times of healthy root surface treatment,while the root surface damage caused by the side was the smallest.In summary,the results of this study suggest that in clinical practice,when removing large and firmly attached calculus,the front and back of the working tip can be appropriately used to effectively remove calculus by using its large oscillating force,or occasionally use the top of the working tip to knock calculus,but prohibiting direct contact between the top and the root surface;After removing the large calculus,the side of working tip should be changed immediately,which can effectively remove plaque or the small amount of loose calculus and reduce the damage of cementum and roughness of root surface while ensuring the removal efficiency. |
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