ABSTRACT
BACKGROUND AND AIM: Orthodontic tooth movement (OTM) is a process whereby the application of a force induces bone resorption on the pressure side and bone apposition on the tension side of the lamina dura. However, only limited data are available on the in vivo behavior of the periodontal tissues. The aim of this study was to assess the changes of periodontal tissues, induced by the orthodontic canine retraction, using 40 MHz ultrasonography. METHODS: Ultrasonographic evaluation of periodontal tissues was conducted in 5 patients with indication for orthodontic treatment. The upper first premolars were extracted bilaterally due to severe crowding, and the canines were distalized using elastomeric chain with a net force of 100 cN. Ultrasonographic scans (US scans) were performed before, during and after retraction, in three distinct areas of the canines buccal surface: mesial, middle and distal. The reference point was the bracket, which appeared hyperechoic on the US scan. Four different dimensions were obtained: D1 (depth of the sulcus), D2 (thickness of the gingiva), D3 (length of the supracrestal fibers), D4 (width of periodontal space). RESULTS: An increase of D1 was observed in all three areas of the periodontium, during orthodontic treatment. D3 was strongly correlated before and immediately after force delivery only for the mesial area (r=0.828, p<0.05). In total, 228 variables were statistically analyzed using Pearson's correlation coefficients, in order to demonstrate the relationship between periodontal findings during orthodontic tooth movement. CONCLUSION: High-resolution ultrasonography has the capability to obviate changes in periodontal ligament space and free gingiva during orthodontic tooth movement.
ABSTRACT
The aim of this case report is to give comprehensive information on the clinical use of computerized axiography (CA) in the evaluation of temporomandibular joint (TMJ) mobility in a patient who undergoes orthognatic surgery. A 20-year-old female patient with class III skeletal anomaly and who underwent orthognatic surgery is presented. Pre- and postsurgical CA recordings for the patient are compared in order to evaluate the functional modifications that appear. The CA is a functional investigation of the TMJ and records the border movements of the mandible: protrusion, lateral movements and open/close. The starting point for every movement is the centric relation position. This allows for very high reproducibility of the CA and the data can later become available for comparison of examinations performed at different times. The CA can offer data to programme an articulator or to evaluate the functional evolution of the TMJs after various occlusal interventions (prosthodontic, orthodontic or orthognatic). After comparing the pre- and postsurgical CA recordings, a significant improvement of the TMJ function after the repositioning of the maxilla and mandible through orthognatic surgery was confirmed. In conclusion, our case confirms the results in literature that CA is a reproducible and reliable investigation method in the evaluation of TMJ function in orthognatic surgery patients, that it facilitates the monitoring of the evolution of the functionality of the TMJ ever time and that it allows for comparative evaluation of the two TMJs.
ABSTRACT
OBJECTIVES: The aim of this study was to investigate the possibility to use high-frequency ultrasound imaging for the assessment of periodontal structures. MATERIAL AND METHODS: A commercially available ultrasound scanner (Ultrasonix SonoTouch) with a linear 1.5 cm footprint, wideband 8 - 40MHz transducer was used, with external transcutaneous approach. A number of 4 patients with healthy periodontal tissue were evaluated. All 4 bicuspids of the lower jaw were imaged from buccal incidence. A fixed landmark (no.20 gutta-percha point) was placed in the gingival sulcus, in order to measure the following dimensions: gingival sulcus depth (D1), free gingival thickness (D2), width of the periodontal space in the most coronal position, length of the supracrestal fiber (D3), height of the clinical crown (D4) and height of the anatomic crown (D5). RESULTS: The 40MHz ultrasound image revealed the cortical bone, tooth crown, dental root, fixed mucosa and the gingival sulcus. The findings for D1 varied between 1.2-1.86 mm and for D2 between 0.65-1.34 mm. The smallest variation of the values was found for D3: 0.21-0.39. The mean value for the difference between D5 and D4 was 1.79 mm. CONCLUSIONS: Ultrasonography provides a highly accurate and noninvasive technique for periodontal assessment. Future studies will be carried out in order to assess the correlation between clinical examination, radiology, and ultrasound measurements in patients with periodontal diseases.
