Dental and Periodontal Changes After Accelerated Correction of Lower Anterior Teeth Crowding With Periodontally Accelerated Osteogenic Orthodontics (PAOO) Procedure: A Randomized Controlled Trial.

Objective To evaluate the relative efficacy of periodontally accelerated osteogenic orthodontics (PAOO) compared to conventional fixed appliances in correcting lower anterior teeth crowding using a non-extraction treatment approach. Material and methods A single-center, two-arm, parallel-group randomized controlled trial was conducted on 38 patients (9 males, 29 females) with moderate crowding. These patients did not require premolar extraction and were randomly allocated into two treatment groups: the PAOO group and the conventional orthodontic treatment group. The Little Irregularity Index (LII) measured crowding intensity on pre-treatment study models. Changes in this index were recorded monthly in both treatment groups. The inter-canine width, inter-second-premolar width, plaque index (PI), gingival index (GI), and papillary bleeding index (PBI) were also measured before and after the leveling and alignment stage. Statistical analysis between the two groups was performed using Mann-Whitney U tests. Results For the LII, the average time for irregularity resolution was three months in the PAOO group, compared to five months in the conventional orthodontic treatment group. Regarding changes in inter-second-premolar width, the PAOO procedure led to a significant decrease in the increase of inter-second-premolar width, with an average increase of +1.52 mm compared to +2.71 mm in the control group. For the GI and PBI, it was found that their values significantly increased with PAOO application, averaging 0.18 and 0.17, respectively, compared to 0.05 and 0.07 in the control group. Conclusions The use of PAOO in orthodontic treatment accelerated the leveling and alignment process by 40%. Changes in the inter-canine width, the inter-second-premolar width, and the status of periodontal tissues were minimal and clinically negligible.

Effectiveness of Flapless Cortico-Alveolar Perforations Using Mechanical Drills Versus Traditional Corticotomy on the Retraction of Maxillary Canines in Class II Division 1 Malocclusion: A Three-Arm Randomized Controlled Clinical Trial.

BACKGROUND AND OBJECTIVES: Both invasive and minimally invasive surgical methods have recently gained popularity in accelerating orthodontic tooth movement. Traditional corticotomy (TC) was one of the first effective invasive surgical techniques in shortening orthodontic treatment time, whereas the flapless cortico-alveolar perforations (FCAPs) technique is a modern minimally invasive method that has recently shown good results in different types of orthodontic tooth movement. Therefore, this study aimed to compare the effectiveness of TC versus FCAPs in maxillary canine retraction when treating Class II division 1 malocclusion patients. MATERIALS AND METHODS: This was a single-blinded, single-center, three-arm randomized controlled trial. A total of 51 patients (22 males, 29 females, mean age 20.98 ± 1.95) whose treatment planning included the extraction of maxillary first premolars were enrolled and randomly divided into three groups: the TC group, the FCAPs group, and the control group. The assessed outcomes were the amount of canine retraction, anchorage loss, and canines' rotation, which was evaluated at five-time points till the completion of canine retraction. RESULTS: There were statistically significant differences in the amount of canine retraction between the three groups in the first two months (p < 0.001), with greater mean values in the TC group (p < 0.001) in the first month. However, the amount of canine retraction in the FCAPs group was significantly greater in the second month compared to the TC group (p = 0.003) and the control group (p < 0.001). In the first month of canine retraction, anchorage loss, and canine rotation were significantly lesser in the TC and FCAPs groups than in the control group (p < 0.001). On the contrary, the canines' rotation amount after the completion of retraction was greater in the TC group than in the other two groups (p < 0.001). CONCLUSION: TC and FCAPs are efficient adjunctive surgical methods for accelerating canine retraction. At the end of the first month, the TC accelerated canine retraction by 59.85% and FCAPs by 44% compared to the conventional retraction. At the end of the second month, the acceleration was less than recorded in the first month (35.44% and 50.20%, respectively). The acceleration effect of the surgical interventions appeared transient and did not last in the following observation period.

The Effectiveness of Periodontally Accelerated Osteogenic Orthodontics (PAOO) in Accelerating Tooth Movement and Supporting Alveolar Bone Thickness During Orthodontic Treatment: A Systematic Review.

The current review aimed to critically and systematically evaluate the available evidence regarding the effectiveness of periodontally accelerated osteogenic orthodontics (PAOO) in accelerating orthodontic tooth movement and supporting the alveolar bone. Additionally, this review aimed to analyze the untoward effects of this procedure and the patient-reported outcome measures. A comprehensive electronic search was performed on 10 databases in addition to a manual search to retrieve all relevant studies. Randomized controlled trials (RCTs) were only included in this review. The interventional group was the PAOO procedure, whereas the control group was either a non-accelerated traditional fixed orthodontic treatment or an accelerated treatment using any other intervention. The Cochrane risk of bias tool for randomized controlled trials (RoB 2) was employed to estimate the risk of bias in the included studies. The current review included eight RCTs evaluating 175 participants (63 males and 112 females) with a mean age ranging from 18.8 to 29.6 years. Five of them assessed the effectiveness of PAOO versus traditional orthodontic treatment, i.e. without any adjuvant surgical intervention. At the same time, the remaining three studies evaluated the effectiveness of PAOO versus corticotomy-only as an adjunctive procedure. The PAOO accelerated the leveling and alignment stage from 39% to 47% and accelerated the retraction of the upper anterior teeth from 41% to 61% compared to conventional orthodontic treatment. One study only indicated that PAOO reduced treatment time by 30.3% versus a corticotomy-only as an adjunctive procedure. No significant side effects have been reported with the PAOO procedure. The PAOO procedure was effective in accelerating orthodontic movement and tended to increase the thickness of the alveolar bone. But most periodontal outcome measures regarding PAOO application were not comprehensively covered in the included trials.

Evaluation of the Levels of Pain, Discomfort, Functional Impairments and Satisfaction With the Periodontally Accelerated Osteogenic Orthodontics (PAOO) When Leveling and Aligning Crowded Teeth: A Prospective Cohort Study.

Background Only a few studies have reported levels of pain, discomfort, functional impairments, and patients' satisfaction after undergoing periodontally accelerated osteogenic orthodontics (PAOO). Therefore, the objectives were to evaluate postoperative pain, discomfort, functional impairments, and satisfaction following this surgical intervention. Methods A prospective cohort study was undertaken at the Department of Orthodontics, University of Damascus Dental School, between August 2018 and November 2020. The sample consisted of 16 patients (4 males, 12 females, mean age: 21±3.05 years) with moderately crowded lower anterior teeth who underwent full-thickness vestibular flap elevation followed by cortical cuts using piezosurgery. Then a bovine xenograft was applied before reflecting the flap and suturing. Fixed orthodontic therapy was then initiated. Questionnaires were administered to assess the levels of pain, discomfort, and oral functional problems using a visual analog scale (VAS) at one day, seven days, 14 days, and 28 days after surgery. The level of satisfaction was also assessed at 28 days postoperatively. Friedman's test was employed, and Wilcoxon signed-rank tests were used for post-hoc tests with an adjusted alpha level. Results On the first day following the PAOO, the mean values of perceived pain, discomfort, swelling, mastication difficulties, swallowing problems, limitation in jaw movements were 80.00, 80.63, 68.13, 78.13, 55.00, and 64.38, respectively. These mean values dropped significantly in the following assessment times (P<0.001). At 28 days following the PAOO, the mean satisfaction score was 84.94±22.46. All patients mentioned that they took painkillers after the surgical intervention. Conclusions On the first day following surgery, patients perceived high levels of pain and discomfort, moderate to severe levels of swelling and chewing difficulties, and suffered from restricted jaw movement. These levels decreased significantly in the following assessment times. Patients' satisfaction with the PAOO procedure was high.

The Diagnostic Accuracy of Cone-Beam Computed Tomography (CBCT) Imaging in Detecting and Measuring Dehiscence and Fenestration in Patients With Class I Malocclusion: A Surgical-Exposure-Based Validation Study.

Background No study has evaluated the diagnostic accuracy of cone-beam computed tomography (CBCT) imaging in detecting bone defects in orthodontic patients with Class I malocclusions. This study aimed to evaluate the accuracy of CBCT in detecting dehiscences and fenestrations before orthodontic treatment compared to the gold standard i.e., the actual clinical detection of bone defects on surgical exposure. Methods A validation study was undertaken at the Department of Orthodontics, University of Damascus between 29 August 2018 and 1 November 2020. The sample included 16 patients who had Class I malocclusion with moderate crowding on the lower anterior teeth. Results The proportion of dehiscence diagnosed on CBCT images was approximately two-and-a-half times greater than that found on direct examination i.e., 42.7% versus 17.7%, respectively. The proportion of fenestrations was almost three times greater when diagnosed on CBCT images compared to the gold standard i.e., 39.5% versus 13.5%, respectively. The sensitivity of CBCT imaging in detecting dehiscence and fenestration was 100%. The specificity of CBCT imaging ranged from 45.5% to 86.7% and from 50% to 86.7% for dehiscence and fenestration detection, respectively. Also, the diagnostic accuracy of CBCT imaging ranged from 44% to 87.5% and from 56% to 87.5% for dehiscence and fenestration detection, respectively. Conclusions The proportion of dehiscence diagnosed on CBCT images was approximately two-and-a-half times greater than that found on direct examination, and the proportion of fenestrations was almost three times greater when diagnosed on CBCT images compared to the gold standard. The CBCT overestimates the dimensions of the linear measurements compared to those measured by the gold standard.

[Interest in myocardial scintigraphy following the arterial switch procedure for transposition of the great vessels]. / Intérêt de la tomoscintigraphie myocardique au décours de la correction artérielle des transpositions des gros vaisseaux.

Coronary artery obstruction is the main late complication of the so-called arterial switch operation designed to repair transpositions of the great arteries in newborn infants by switching the great vessels and transferring the coronary ostia onto the posterior vessel. Our aim was to study the links between myocardial perfusion and coronary artery anatomy after the arterial switch operation. Forty-five patients (5.863 years) underwent a 201Tl myocardial SPECT and a selective coronary artery angiography. The latter was normal in 20 children: 13 had also a normal myocardial scan but 7 had myocardial perfusion defects including 2 with angina who had a very low coronary reserve at positron emission tomography. Twenty-five patients had severe coronary artery lesions: 5 with a normal myocardial scan and 20 with perfusion defects. Twelve out of these 20 underwent surgical revascularization and the SPECT images went back to normal in all within 6 months after surgery. Specificity and sensitivity of myocardial SPECT in detecting coronary artery lesions were 78% and 69% whereas positive and negative predictive values were 74 and 73%. We conclude that myocardial SPECT imaging is not the right way to detect late post arterial switch coronary artery lesions. It is helpful in decision making as to submit these children to surgical revascularization and in assessing its postoperative effectiveness.

Simulations of the thermo-acoustic lens effect during focused ultrasound surgery.

Laboratory measurements of soft tissue properties show a dependence of background propagation properties on temperature. For typical focused ultrasound surgery (FUS) applications, only the slow variations in tissue background parameters need to be accounted for when computing the outcome of a FUS sonication. The cumulative effect of slowly varying sound speed has been referred to in the literature as a thermal lens, or a thermo-acoustic lens because of its beam-distorting properties. An algorithm to solve the coupled acoustic-thermal problem is described, and numerical results are presented to illustrate the effects of dynamic sound-speed profiles in layered tissues undergoing FUS. The results of simulations in liver with and without a fat layer indicate that the thermal-acoustic interaction results in more complex dynamics in FUS than a simple model will predict. Both the size and the position of the lesions predicted from the simulations are affected by the thermo-acoustic lens effect. However, the overall effect from short sonications at high power from sharply focused single element sources (F-no. from 0.8 to 1.3) around 1 MHz similar to those used in clinical setups is found to be small.

Amplitude degradation of time-reversed pulses in nonlinear absorbing thermoviscous fluids.

The linear wave equation in a lossless medium is time reversible, i.e., every solution p(x, t) has a temporal mirror solution p(x, -t). Analysis shows that time reversal also holds for the lossless nonlinear wave equation. In both cases, time-reversal invariance is violated when losses are present. For nonlinear propagation loses cannot normally be ignored; they are necessary to prevent the occurrence of multivalued waveforms. Further analysis of the nonlinear wave equation shows that amplification of a time-reversed pulse at the array elements also leads to a violation of time reversal even for lossless nonlinear acoustics. Numerical simulations are used to illustrate the effect of nonlinearity on the ability of a time-reversal system to effectively focus on a target in an absorbing fluid medium. We consider both the amplitude and arrival time of retrodirected pulses. The numerical results confirm that both shock generation (with the accompanying absorption) and amplification at the array, adversely affect the ability of a time-reversal system to form strong retrodirective sound fields.

FDTD simulation of finite-amplitude pressure and temperature fields for biomedical ultrasound.

Full wave simulations provide a valuable tool for studying the spatial and temporal nature of an acoustic field. One method for producing such simulations is the finite-difference time-domain (FDTD) method. This method uses discrete differences to approximate derivatives in the governing partial differential equations. We used the FDTD method to model the propagation of finite-amplitude sound in a homogeneous thermoviscous fluid. The calculated acoustic pressure field was then used to compute the transient temperature rise in the fluid; the heating results from absorption of acoustic energy by the fluid. As an example, the transient temperature field was calculated in biological tissue in response to a pulse of focused ultrasound. Enhanced heating of the tissue from finite-amplitude effects was observed. The excess heating was attributed to the nonlinear generation of higher-frequency harmonics which are absorbed more readily than the fundamental. The effect of nonlinear distortion on temperature rise in tissue was observed to range from negligible at 1 MPa source pressure to an 80% increase in temperature elevation at 10 MPa source pressure.