Biomechanical effect of combined use of mini-screws and aligners in preventing uncontrolled tipping of the incisor and mesial tipping of the molar: a three-dimensional finite element study.

Esthetic orthodontic treatment with a double J retractor and temporary anchorage devices

To compare the space closure, root resorption and canine angulation during en-masse retraction of the labial segment after extraction of first premolars with or without interseptal bone reduction distal to the maxillary canines. A single-centre, parallel randomised control trial included 16 participants with a mean age of 21.5 years. Participants were allocated into treatment groups using blocked randomisation, and blinding was employed for outcome assessors and data analysts. The control group consisted of eight participants who underwent extraction of maxillary first premolars only, while the experimental group included eight participants who underwent interseptal bone reduction immediately after premolar extraction. En-masse retraction was performed using conventional friction mechanics with anchorage reinforcement in both groups. Measurements of space closure were conducted over 3 consecutive months during retraction. The time taken for total space closure was recorded. Cone-beam computed tomography scans were taken before and 3 months after retraction to assess root resorption and canine angulation. The experimental group demonstrated a significant increase in the rate of en-masse retraction compared to the control group over 3 months (mean difference [MD] = 1.09 mm, 95% confidence interval [CI] = 0.78-1.40), with an overall space closure rate of MD 0.26 mm/month (95% CI = 0.17-0.34). However, these changes were of minimal clinical significance. The change in canine angulation (MD = 4.50°, 95% CI = -1.61-10.61) did not exhibit statistical significance. Substantial root resorption was observed in six maxillary anterior teeth, with no difference between the groups. Interseptal bone reduction is a minimally invasive surgical technique, resulting in an accelerated rate of en-masse retraction in the experimental group over 3 months. However, despite the statistical significance, the clinical impact on overall space closure was minimal, with a difference of only 0.26 mm/month observed between the groups. Interseptal bone reduction did not affect the change in canine angulation and root resorption.

The effect of different extraction sites upon incisor retraction

To compare the efficiency in anchorage preservation of conventional and self-ligating brackets after the extraction of first maxillary premolars using differential moment mechanics. Thirty-eight patients requiring extraction of maxillary first premolars and maximum anchorage during space closure were evaluated based on bracket type. Group 1, comprising 23 patients, was bonded with preadjusted conventional brackets (CBs) with a slot of 0.022-inch × 0.030-inch. Group 2 comprised 15 patients who were bonded with 0.022 inch preadjusted self-ligating brackets (SLBs). Patients in both groups received a nickel titanium (NiTi) intrusion arch and a 150 g NiTi closing coil spring for separate canine retraction, followed by a continuous mushroom loop archwire to retract the incisors. Lateral cephalograms were available at the start of treatment (T1) and at the completion of space closure (T2). Statistical comparisons were performed with paired and unpaired Student's t-tests. No significant differences were found between the groups in maxillary molars anchorage loss (3.87 ± 1.35 mm and 3.65 ± 1.73 mm for the CB and SLB groups, respectively). Only the mean vertical movement of the tip of the incisor was significantly different between the groups (CB = -0.92 ± 1.46 mm; SLB = 0.56 ± 1.65 mm). There were no significant differences in the amount of anchorage loss of the maxillary first molars between SLB and CB systems during space closure using differential moments.

Anchorage loss (AL) is a potential side effect of orthodontic mechanotherapy. In the present study, it is defined as the amount of mesial movement of the upper first permanent molar during premolar extraction space closure. In addition, AL is described as a multifactorial response in relation to the extraction site, appliance type, age, crowding, and overjet. For this study, 87 university clinic and private practice subjects, who were defined as maximum anchorage cases and had undergone bilateral maxillary premolar extractions, were divided into four groups according to extraction site (first vs second premolars), mechanics (lingual vs labial edgewise appliances), and age (adolescents vs adults). Overjet and crowding were examined from the overall sample. Data were collected from serial lateral cephalograms and dental casts. The results showed that as the severity of dental crowding increased, AL significantly decreased (r = -0.66, P = .001). Labial edgewise appliances demonstrated a significantly greater AL than did lingual edgewise appliances (1.15 +/- 2.06 mm, P < .05). A greater, though not statistically significant, AL was found in adults than in adolescents (0.73 +/- 1.43 mm). There was a slight nonsignificant increase in AL between maxillary second compared with first premolar extractions (0.51 +/- 1.33 mm). Overjet was weakly correlated to AL. These results suggest that AL is a multifactorial response and that the five examined factors can be divided into primary (crowding, mechanics) and secondary factors (age, extraction site, overjet), in declining order of importance.

Orthodontic treatment for a patient with hypodontia involving the maxillary lateral incisors

Calcaneus fracture pattern and severity: Role of local trabecular bone density

To evaluate anchorage loss after en masse retraction in bimaxillary dentoalveolar protrusion patients using friction vs frictionless mechanics. Thirty patients with bimaxillary dentoalveolar protrusion needing extraction of upper first premolars and en masse retraction with maximum anchorage were included in this two-arm, parallel, single-center, single-blinded randomized clinical trial with a 1:1 allocation ratio using fully sealed opaque envelopes. Friction group retraction utilized elastomeric power chain between miniscrews and hooks crimped mesial to upper canines on 17 × 25 stainless steel archwire. Frictionless group used customized T-loop springs loading upper first molars indirectly anchored to miniscrews. Activation was every 4 weeks until full retraction. The primary outcome assessed was anchorage loss evaluated at cusp tip and root apex of the first molar. First molar rotation, incisor tip and torque, and root resorption of anterior teeth were evaluated on digital models and cone beam computed tomography taken before and after space closure. Anchorage loss at crown of first molar was significantly more in frictionless group by 2.1 mm (95% CI = -0.4 to 3.5), (P = .014), while there was no significant difference in anchorage loss at root apex between groups. Significant mesial in molar rotation of 6.672° (95% CI = 12.2-21.2), (P = 0.02) was greater in the frictionless group. Both groups showed comparable tip, torque, and root resorption values. No severe harms were reported. There was mild gingival overgrowth and inflammation in the frictionless group due to T-loop irritation. Extra anchorage considerations are needed during en masse retraction when frictionless mechanics is implemented as higher anchorage loss and molar rotation were detected. No difference in tip, torque, and root resorption was observed.

The supraspinatus is most frequently involved in rotator cuff tears, a common orthopaedic condition. However, the architecture of this muscle has been described only for the superficial, anterior, and posterior regions. To determine the muscle architecture of the deep supraspinatus. Descriptive laboratory study. Muscle architecture measurements were collected from 25 cadaveric supraspinatus specimens (13 intact [without tendon tears], 3 with partial-thickness tears, 9 with full-thickness tears). The muscle was divided into deep, superficial anterior, and superficial posterior regions. Pennation angle, raw and normalized fiber length, and sarcomere length and number were compared using repeated-measures analyses of variance. First, mean architecture measurements were compared between regions using only the intact specimens (n = 13). The deep region had a lower mean pennation angle (3.3° ± 1.0°) compared with the posterior region (11.0° ± 3.9°; P < .0001), which in turn had a significantly higher pennation angle compared with the anterior region (7.6 ± 2.6°; P = .0005). Normalized fiber lengths in the deep region were 21.1% (P = .0052) and 34.5% (P < .0001) shorter than the posterior and anterior normalized fiber lengths, respectively. Sarcomere lengths in the deep region were longer (3.4 ± 0.2 μm) compared with the posterior (3.1 ± 0.2 μm; P = .0012) and anterior (3.2 ± 0.2 μm; P = .0390) regions. Sarcomere numbers also decreased in the deep region by 21.2% (P = .0056) and 34.2% (P < .0001) compared with the posterior and anterior regions, respectively. The deep supraspinatus had significantly lower pennation angles, shorter fiber lengths, and fewer but longer sarcomeres in series compared with other subregions within the muscle. These structural differences suggest a functionally unique "submuscle" within the supraspinatus. Understanding the architecture of the supraspinatus muscle can provide insight into muscle function in health and disease. Specifically, this deep submuscle may play a different role in rotator cuff function than the rest of the muscle.

This retrospective study assessed the difference in anchorage loss using 3D superimposition of study models between cases treated with extraction of maxillary first premolars and maxillary second premolars carried out in orthodontic specialist practice. Sixty subjects who have undergone extractions of either maxillary first or second premolars as part of their orthodontic treatment were selected. Eligibility criteria included patients with a Class I, mild Class II or III malocclusions, mild-to-moderate crowding with no anchorage reinforcement. Pre- and post-treatment maxillary dental study cases were scanned using a surface laser scanner to produced 3D digital images which were superimposed using areas of stability on the anterior hard palate. Anchorage loss was measured by the mesial movement of the maxillary first permanent molar. The mean mesial movement for the maxillary first molars, when adjusted for confounding factors was 4.7 mm (SD 1.6) in the maxillary first premolar extraction group and 4.6 mm (SD 1.6) in the maxillary second premolar extraction group. There is no difference in anchorage loss when comparing the extraction of the maxillary first premolars to the extraction maxillary second premolars.

Introduction: The aim of this study was to compare the clinical effectiveness of nickel titanium (NiTi) closed coil spring and elastomeric chain on rate of space closure in terms of anterior retraction and anchor loss. Materials and Methods: A total of 40 patients with first premolar extraction were randomly divided into two groups for space closure. Group 1 consisted of 20 patients in whom space closure was done with NiTi closed coil springs whereas in group 2 consisted of 20 patients with elastomeric chain. The amount of anterior retraction, anchor loss and rate of space closure was measured before start of retraction and at end of 4 months clinically and radiographically. Results: The observations obtained in the study were subjected to statistical analysis, so as to get their interpretation. All qualitative variables were compared using Fisher exact test. All quantitative variables were described using mean ± standard deviation and compared using unpaired t-test. P < 0.05 was considered as significant. The unpaired t-test, when applied, revealed there was a faster rate of space closure by NiTi closed coil springs when compared with elastomeric chain. Furthermore, anchor loss was more with NiTi springs as compared with elastomeric chain. Conclusion: The results of this study demonstrated faster space closure (with anterior retraction) along with significant anchorage loss was achieved by using NiTi closed coil springs when compared to the elastomeric chain.

Anchorage reinforcement with miniscrews and molar blocks in adolescents: A randomized controlled trial

S. Baumgaertel M.R. Razavi M.G. Hans Mini-implant anchorage for the orthodontic practitioner Am J Orthod Dentofacial Orthop 133 4 2008 621 627

Impact of implant location on the prevalence of peri-implantitis: A systematic review and meta- analysis

The dorsal surface of the tongue of the little tern, Sterna albifrons, has a distinctive anterior region for five-sixths of its length and a terminal posterior region. The anterior region observed by scanning electron microscopy is distinguished along its forward half by a median line from which median papillae protrude. The hind half of the anterior region has a median sulcus without papillae. The deciduous epithelium on both sides of the median line and sulcus bears scattered epithelial protrusions. The posterior lingual region has neither median papillae nor deciduous epithelium. So-called giant conical papillae are located in a transverse row between anterior and posterior regions. Delicate microridges adorn the surfaces of all outer epithelial cells in both regions. Examination of the dorsal lingual epithelium by light and electron microscopy provides histologic and cytologic criteria for distinguishing anterior and posterior regions. Basal cells are nearly alike throughout the dorsal epithelium. Intermediate layer cells of the anterior region contain numerous tonofibrils in electron-dense bundles composed of 10 nm tonofilaments. The outer layer is composed of electron-dense, well-keratinized cells, and electron-lucent epithelial protrusions are present on the exposed surface of the outermost cells. Median papillae are composed of typical keratinized cells, which are nearly filled with keratin filaments. Intermediate layer cells in the posterior region of the tongue are nearly filled with unbundled tonofilaments. There is only a very thin outer keratinized layer in this region.