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Effect of Piezopuncture on Tooth Movement and Bone Remodeling in Dogs By Kim et al. (AJODO July 2013)

Introduction 

Various surgical interventions on the periodontal tissues have been developed to accelerate orthodontic tooth movement.



Intentional surgical damage evokes a regional acceleratory phenomenon that causes transient osteopenia by an accelerated remodeling process.



Various modifications of corticotomies are effective in increasing cellular activities related to tooth movement.



Corticision was introduced as a minimally invasive alternative for cortical activation.



A cortical incision made by malleting a scalpel to separate the interproximal

cortices

was

found

acceleratory phenomenon effect.

to

induce

the

regional



Piezopuncture is a procedure in which an ultrasonic tool, a piezotome, is used to create multiple cortical punctures through the overlying gingiva.



These transmucosal manipulations of alveolar bone have minimized morbidity and achieved similar results to more aggressive procedures, including extensive flap elevation for rapid tooth movement.

Aim of Study 

To determine whether piezopuncture would elicit the regional acceleratory phenomenon and accelerate tooth movement without causing harmful tissue responses.



To compare the acceleration rates of tooth movement and bone remodeling between the maxilla and the mandible.

Materials & Method 

Sample size: Ten male beagles (age, 18-24 months; weight, 9-12 kg)



The dogs were randomly divided into 2 groups: control (n = 4) and piezopuncture (n = 6).



These groups were further divided into 3 sub-groups based on the duration of force application: group I, 14 days; group II, 28 days; and group III, 42 days.



Each animal provided 4 specimens (1 each from the right and left sides of both jaws), and the maxillary and mandibular specimens (n = 20 for each jaw) were randomly divided into 2 groups.



Target teeth = second premolars



Anchorage teeth





Maxillary arch  Canine



Mandibular arch 3rd premolar

Orthodontic buttons connected by a lever arm were bonded on the labial surfaces of all experimental teeth with Super-Bond C&B resin (Sun Medical, Shiga, Japan).



A NiTi closed-coil spring (Tomy International, Tokyo, Japan) was activated and ligated between the lever arms of the target teeth and the anchorage teeth.



For reinforcing anchorages, resin bridges were constructed on the adjacent teeth.



The orthodontic force by the appliance was 100 g at the beginning of the experiment.



A piezosurgical instrument was used to perform the cortical punctures penetrating the gingiva



The depth of cortical injury was 3 mm, by holding the tip perpendicular to the gingiva for 5 seconds under saline-solution irrigation.



Piezopunctures were performed on the MB, DB, ML, and DL sides of the second premolars. Total Sixteen punctures were made on 1 target tooth.



Gentamicin (7.5 mg/kg) was injected postoperatively for 3 days. Tooth brushing and daily hexamedine irrigation were repeated during the postoperative care.



Tooth movement was measured by a digital caliper (Mitutoyo, Kawasaki, Japan) on the stone models once a week.



Histologic analysis was performed on the decalcified specimens at 2, 4, and 6 weeks.



Quantitative histomorphometric analysis was done on the nondecalcified specimens of the dogs in the 6- week groups.



Microphotographs of all specimens were recorded using a digital CCD camera (PS30C ImageBase; Kappa Optronics, Gleichen, ).



The outlines of labeled bones were traced from the photographs, and the distances between the labeled lines were measured with image

analysis

Optronics).

software

(ImageBase

Metreo

2.5;

Kappa

Statistical analysis 

Descriptive statistics were represented as means and standard deviations for all parameters in each group.



The normality of the data was assessed with the KolmogorovSmirnov test.



Independent t tests were used to evaluate the intergroup differences of the mean tooth movement distances on the models and the mean accumulated new bone deposition measured by histomorphometric analysis.

Results 

The distance of the maxillary 2nd premolar movement in the piezopuncture group was 3.26-fold greater than that in the control group.



The distance of the mandibular 2nd premolar movement in the piezopuncture group was 2.45-fold greater than that in the control group.



There was no significant difference in the amount of anchorage tooth movement between the piezopuncture group and the control group.



With respect to movement rate, the first 2 weeks in the maxilla and the second week in the mandible had the greatest movement.



The weekly velocity of tooth movement in the piezopuncture group was larger than that in the control group at all observation times.

Histological findings (Compression sides of moving teeth ) 

At week 2, 

Control group  Compression and Hyalinization of PDL, with no apparent resorptive findings on the alveolar surfaces.



Piezopuncture group  Osteoclasts with the resorption lacunae along the bone surfaces were seen near hyalinized areas of the periodontal ligament .



At week 4, 

Control group Indirect Resorption followed by the removal of the hyalinized PDL.



Piezopuncture group  Direct Resorption by active boneresorbing cells continued.



At week 6, 

Control group  The number and the activity of bone-resorbing cells were decreased.



Piezopuncture group  Direct bone resorption with the cellular periodontal ligament continued.

Fluorescent Microscopic Findings( 

On tension side)

The total distance of newly mineralized bone apposition during 6 weeks was significantly greater in the piezopuncture group than in the control group.



In the maxilla, the mean apposition length of the piezopuncture group was 2.55-fold greater than that of the control group.



In the mandible, the mean apposition length in the piezopuncture group was 2.35-fold greater than that in the control group.

Discussion 

Piezopuncture was developed to increase patient compliance by minimizing discomfort during and after surgery, and to simplify the procedure for orthodontists.



Piezopuncture eliminates the use bone malleting, which can be frightening to the patient, and the soft-tissue incision and suture.



However, the intensity and duration of the regional acceleratory phenomenon might not be sufficient to function throughout the entire orthodontic treatment. This requires repeated applications at regular intervals.



The action mechanism of piezopuncture is based on the biologic concept of cortical activation rather than cortical removal.



Garg et al emphasized that the regional acceleratory phenomenon is initiated mainly by trauma to the cortical bone.



Only cortical activation can increase osteoclastic activity around the periodontal ligament, facilitating bone turnover toward an osteoporotic state with less tissue resistance to tooth movement.



Piezosurgical incisions have been reported to be safe and effective in osseous surgeries, such as preprosthetic surgery, alveolar crest expansion, and sinus grafting.



Vercellotti et al used a piezosurgical technique for periodontally accelerated orthodontic tooth movement.



Dibart et al introduced piezocision as a modified method of corticision for rapid orthodontic tooth movement.



The rates of tooth movement in the control group showed no remarkable increase until 5 weeks after intervention. On the other hand, the piezopuncture group showed earlier acceleration of tooth movement in the first 2 weeks after intervention.



The biologic lag phase of tooth movement is byed in piezopuncture group, indicating less production and faster elimination of hyalinized tissue.



The acceleration effect of piezopuncture was faster in the maxilla than in the mandible.



Deguchi et al reported that orthodontic tooth movement progressed 2 weeks faster in the maxilla than in the mandible.



This may be because of the differences of bone density and metabolism between the jaws.

Conclusion 

Piezopuncture was found to evoke rapid tooth movement by accelerating the rate of alveolar bone remodeling.



Piezopuncture might have a great therapeutic benefit in the context of reducing treatment duration and also periodontal regeneration.



This development is expected to bring orthodontics closer to the goal of efficiency in tooth movement, without causing patient discomfort or damage to the teeth and their ing tissues.