Plaque is the initial factor of periodontitis, and calculus is the most important local stimulation factor.
periodontal basic treatment is the most basic treatment plan and measure for all patients with periodontitis. The purpose is to remove plaque, calculus and other plaque retention factors, eliminate inflammation, and reduce the damage of teeth and surrounding soft tissue as much as possible
Periodontal ultrasonic therapy can not only remove dental surface sediment efficiently by high frequency oscillation force, but also has a unique effect on plaque clearance caused by cooling water and micro flow force. In addition, its clinical effect is similar to that of manual curettage, so it has become an important part of daily periodontal treatment There are two methods to evaluate the root surface damage after periodontal treatment. One is to judge the root surface damage by observing whether there are scratches, pits and cementum exfoliation (loss) under the scanning electron microscope; The other is to measure the root surface roughness.
research found that the root surface damage can affect the adhesion of bacteria, the attachment of fibroblasts and blood cells, and the stability of fiber framework, thus affecting the healing of periodontal tissue
The efficiency of removing sediment and the damage to the root surface of periodontal ultrasonic therapeutic instrument has strong technical sensitivity. Only by fully understanding its type, understanding the principle of influencing factors such as the shape, diameter and power of ultrasonic working tip, correctly selecting the working tip with appropriate shape and diameter and power of appropriate size, and standardizing the use of operation technology, can the high efficiency of cleaning be achieved (2) the types of dental surface damage caused by a 603 and manual scaling were also reviewed
Comparison of ultrasonic and manual scaling in periodontal treatment
Clinical effect: the clinical indicators of periodontitis include probing depth (PD), clinical attachment level (CAL) and probing bleeding (BOP).
clinical study found that ultrasonic treatment or manual scaling can reduce the depth of periodontal pocket and obtain clinical attachment, and the improvement effect of the two methods is similar The effect of ultrasonic treatment on removing sediment: compared with manual curettage, ultrasonic treatment is time-saving and efficient. In some studies, ultrasonic treatment instrument and manual curettage were used to scrape the extracted teeth with the same level of root calculus until there was no visible calculus. The scanning electron microscope observation showed that there was no difference in the residual level of root calculus between the two methods
The results showed that the bacterial content (Porphyromonas gingivalis, Actinobacillus actinomycetes, forsythmia, Treponema denticulatum, etc.) decreased significantly after ultrasonic treatment and manual curettage Compared with the manual scalpel, the subgingival working tip of the periodontal ultrasonic treatment instrument is more round and blunt than that of the manual scaler, and the working tip is smaller and easier to enter the deep part of the periodontal pocket and the root bifurcation area. The damage range of the plaque biofilm caused by the cavity effect and microfluidic force can be extended beyond the root surface contact point of the working canine
Some studies have shown that periodontal ultrasonic treatment and manual curettage have the same effect on reducing the number of bacteria in the first degree of root furcation lesions, however, in reducing the number of bacteria in the second and third degree root furcation lesions, ultrasonic treatment has more advantages Root surface damage: many studies have compared the root surface damage after ultrasonic treatment and manual curettage. The results show that the roughness of the root surface after the two methods is similar, and scratches can be seen under the electron microscope, while manual curettage can scrape more cementum. Multiple curettage can lead to local dentin exposure, which may cause root sensitivity or pulp symptoms, and affect the comfort and compliance of patients
Types of periodontal ultrasonic therapeutic apparatus
The periodontal ultrasonic therapeutic instrument is mainly composed of generator (host), transducer (mobile phone) and working tip The generator sends out high-frequency electric energy, which is converted into ultrasonic vibration by transducer, and finally transmitted to the working tip, causing high-frequency oscillation of the working point to remove the calculus. In addition, the energy generated by the high-frequency oscillation of the working point is transferred to the surrounding cooling water, and the cavitation effect and micro flow force also contribute to the removal of plaque and calculus
According to the different transducers, periodontal ultrasonic therapeutic instruments can be divided into magnetostrictive type and piezoelectric ceramic type.
two types of periodontal ultrasonic therapeutic instruments have similar effects in the removal of plaque and calculus, and can achieve satisfactory clinical effects, but the research results on root surface morphology are different Santos et al. Used two types of periodontal ultrasonic therapeutic instruments to pull out the teeth after subgingival scaling in the mouth of patients with periodontitis. The results showed that the root surface cementum loss was more and the root surface roughness was larger (4.4 mu; mvs4.1 mu; m); Mittal et al. Also carried out similar experiments, and found that the root surface cementum loss was more, but the roughness was smaller (1.43 mu; mvs1.55 mu; m). In the experiment of subgingival scaling of periodontitis in vitro, yousefimanesh et al. Found that the root surface cementum loss was more and the root surface roughness was larger after the magnetostrictive curettage; On the contrary, Singh et al. Found that the cementum loss and root surface roughness of the piezoelectric ceramic curettage were larger (2.8 mu; mvs2.5 mu; m)
3.1 motion type (or trajectory)
used to think that the movement type of the working tip of the two kinds of periodontal ultrasonic therapeutic instruments was determined by the transducer. The working tip of magnetostrictive periodontal ultrasonic therapy instrument produced elliptical motion, while the working tip of piezoelectric ceramic periodontal ultrasonic therapy instrument produced linear movement However, Lea et al. Used 3D laser vibration to study the movement types of the working tips of magnetostrictive and piezoelectric ceramic periodontal ultrasonic therapeutic instruments under no-load and load, high output power and low output power, respectively. It was proved that the motion of the two types of working tips is ellipse, which can change from narrow ellipse to wide ellipse
This change is mainly affected by the shape and power setting of the working tip. The thinner the working tip is, the higher the power setting is, the more likely it is to produce a wide oval motion; while the thicker the working tip and the lower the power setting, the narrower the elliptical motion may be, which is similar to the one produced by the piezoelectric ceramic periodontal ultrasonic therapeutic instrument; The results show that the amplitude of the long axis and the minor axis of the ellipse in the narrow elliptical motion are different greatly, and the oscillating force in the long axis direction is larger than that in the short axis direction; the amplitude difference between the long axis and the short axis of the ellipse in the wide elliptical motion is small, and the oscillation force is dispersed
3.2 working face
The effective area of the working tip is the free end of the working tip, which is about 4mm long. The vibration produces the largest displacement amplitude, which can effectively remove the plaque and calculus The effective area of the working tip can be divided into front, back, side and tip. The face which is consistent with the bending direction of the working tip is the front (ventral), the corresponding face is the back, both sides are the side, and the end of the working tip is the tip
The force generated by the elliptical motion oscillation of the working tip can be dispersed on each surface and tip of the working tip, so that all surfaces can play a role. However, the displacement amplitude of each surface caused by the vibration of the working tip is different. The amplitude of the front and back of the working point (the long axis of the ellipse) is greater than that of the side (the short axis of the ellipse). The greater the amplitude, the greater the oscillation force The results show that the oscillating force of the front and back of the tip is greater than that of the side; the force generated by the contact between the working tip and the root surface can be divided into transverse shear force parallel to the root surface and vertical component force perpendicular to the root surface Because of the small surface area and concentrated energy output, the tip of working tip can not contact tooth surface or root surface vertically
The working tip diameter refers to the width and thickness of the effective area of the working tip, which can be divided into standard diameter, fine diameter and ultra-fine diameter.
working tip diameter can affect the strength of oscillating force of working tip. Under the same power and lateral pressure, the large-diameter working tip has higher efficiency in removing dental calculus, but it will cause more root surface damage
The diameter of the working tip also affects the cavitation effect and microfluidic force. Walmsley et al. Found that the cavitation effect and microfluidic force are stronger when the working tip with large diameter is unloaded; Therefore, for the treatment sites with large or medium amount of calculus, the use of large diameter work tip can improve the efficiency of removing calculus, but it is easy to cause root surface damage; When the treatment site is plaque or a small amount of calculus, the small diameter working tip can not only reduce the root surface damage, but also meet the requirements of plaque removal, and at the same time produce stronger hole effect
The shape of the working tip refers to the cross-section shape of the effective area of the working tip, which is generally rectangular or circular. The shape of the working tip can affect the oscillation force and the size of the hole effect The results of lea et al. Show that the oscillating force of rectangular working tip is greater than that of cylindrical working tip under the same diameter, which can effectively remove calculus, but also cause more damage to root surface tissue.
rectangular working tip has stronger hole effect than cylindrical working tip with the same diameter because its shape is more conducive to water displacement than cylindrical working tip with the same diameter
When the root surface is concave, the convex surface of the cylindrical working tip is easier to fit with the root surface than the rectangular flat surface. In recent years, the spherical tip for root bifurcation has also appeared, with a 0.8mm diameter ball at the end to adapt to the anatomical structure of root bifurcation
The greater the power, the greater the amplitude, the greater the oscillation force, and the higher the efficiency of sediment removal. However, it will increase the loss of root tissue and root surface roughness, resulting in root surface damage.
in clinical practice, it is necessary to select a minimum effective power according to the type of sediment
ultrasonic therapeutic instrument can not only remove sediment efficiently, but also avoid root surface damage. Therefore, when removing large calculus, we should choose middle and high-grade power, increase the oscillating force of working tip to ensure the efficiency of removing calculus, but the working tip can only act on the calculus, not directly on the root surface It has been found that in the case of no damage to the root surface, the hole generated by the displacement amplitude in the middle power range has the largest effect, and the removal efficiency of biofilm is the highest
In the study of Kumar et al., low, medium and high power were set up to scrape the root surface of orthodontic extracted teeth for 8-10 times. The results showed that the root surface roughness was the smallest at medium power (16.1 mu; m, 10.71 mu; m, 12.8 mu; m); m) A 6032
therefore, a moderate power should be selected to remove a small amount of calculus and plaque, which can produce the largest hole effect, and the root surface roughness is the smallest
5.1 working Perspective
When the effective area of the working tip contacts with the root surface, a certain angle will be formed (0 ~ 90 deg; ）The larger the angle, the greater the loss and roughness of the root surface.
studies have shown that the force generated by the contact between the working tip and the root surface can be divided into transverse shear force parallel to the root surface and vertical component force perpendicular to the root surface; When the working tip is parallel to the root surface (0 deg;), the transverse shear force is the largest, so the efficiency of removing calculus is the highest and the damage to the root surface is the least; A 6032 a 6032 a 6032
5.2 side pressure
When the ultrasonic therapeutic instrument is operated, the oscillating working tip contacts with the root surface to generate lateral pressure (load) without increasing the artificial lateral pressure. If the artificial force is applied, it will affect the clearance efficiency of the working tip and cause root surface damage The results showed that with the increase of lateral pressure, the displacement amplitude of the working tip decreased, and the oscillating force decreased accordingly, which affected the efficiency of dental calculus removal; Arabaci et al. Found that the increase of lateral pressure led to the increase of root surface roughness
In conclusion, it is necessary to select the appropriate periodontal ultrasonic therapeutic instrument according to the type of sediment in clinical work When removing large and firmly attached calculus, large size rectangular working tip can be selected, medium and high-grade power should be set, front and back of working tip should be used properly. The working tip should be parallel to the root surface as far as possible without artificial side pressure. Moreover, the working tip can only act on the calculus and should not directly contact the root surface After the removal of large calculus, it should be replaced by a cylindrical working tip with a small diameter in time, select a medium power, and try to use the side of the working tip as far as possible, which can effectively remove plaque or a small amount of loose calculus, ensure the removal efficiency, and reduce the root surface damage and roughness
Source: Zhang Lina, Ren Xiuyun. Research progress on Influencing Factors of periodontal ultrasonic treatment on root surface damage [J]. Chinese Journal of Practical Stomatology, 2019 (07): 434-438