-
EFORT Open Reviews Oct 2021The biomechanics of the shoulder relies on careful balancing between stability and mobility. A thorough understanding of normal and degenerative shoulder anatomy is... (Review)
Review
The biomechanics of the shoulder relies on careful balancing between stability and mobility. A thorough understanding of normal and degenerative shoulder anatomy is necessary, as the goal of anatomic total shoulder arthroplasty is to reproduce premorbid shoulder kinematics.With reported joint reaction forces up to 2.4 times bodyweight, failure to restore anatomy and therefore provide a stable fulcrum will result in early implant failure secondary to glenoid loosening.The high variability of proximal humeral anatomy can be addressed with modular stems or stemless humeral components. The development of three-dimensional planning has led to a better understanding of the complex nature of glenoid bone deformity in eccentric osteoarthritis.The treatment of cuff tear arthropathy patients was revolutionized by the arrival of Grammont's reverse shoulder arthroplasty. The initial design medialized the centre of rotation and distalized the humerus, allowing up to a 42% increase in the deltoid moment arm.More modern reverse designs have maintained the element of restored stability but sought a more anatomic postoperative position to minimize complications and maximize rotational range of motion. Cite this article: 2021;6:918-931. DOI: 10.1302/2058-5241.6.210014.
PubMed: 34760291
DOI: 10.1302/2058-5241.6.210014 -
The Angle Orthodontist Jul 2018To evaluate the quantitative effects of miniscrew supported appliances for maxillary molar distalization in Class II malocclusion.
OBJECTIVES
To evaluate the quantitative effects of miniscrew supported appliances for maxillary molar distalization in Class II malocclusion.
MATERIALS AND METHODS
The systematic search included MEDLINE, EMBASE, CINAHL, PsychINFO, Scopus, and key journals and review articles. The date of the last search was January 30, 2017. Methodological quality of the retrospective studies was graded by means of the Quality Assessment Tool for Quantitative Studies, developed for the Effective Public Health Practice Project (EPHPP) and prospective studies by means of Newcastle-Ottawa Scale.
RESULTS
In total, 298 studies were identified for screening, and 14 studies were eligible. The Quality Assessment Tool for Quantitative Studies rated all of the four included retrospective studies as moderate. The Newcastle-Ottawa Scale rated seven studies as high quality and three studies as low quality. The mean molar distalization values varied from 1.8 mm to 6.4 mm. Mean distal tipping of molars varied from 1.65° to 11.3°. The mean distal movement of premolars and incisors varied from 1.75 mm to 5.4 mm and 0.1 mm to 2.7 mm, respectively.
CONCLUSIONS
Miniscrew-supported appliances are effective in molar distalization with distal movement of premolars with minimal anchorage loss and distal tipping of the molar teeth.
Topics: Bone Screws; Humans; Malocclusion, Angle Class II; Maxilla; Molar; Orthodontic Anchorage Procedures; Tooth Movement Techniques
PubMed: 29664335
DOI: 10.2319/091717-624.1 -
Zhong Nan Da Xue Xue Bao. Yi Xue Ban =... Oct 2021At present, the research on clear aligner of molar distalization mainly focuses on the upper jaw, while the research on mandibular molars is few.This study aims to...
OBJECTIVES
At present, the research on clear aligner of molar distalization mainly focuses on the upper jaw, while the research on mandibular molars is few.This study aims to evaluate the therapeutic effect of mandibular molars distalization with clear aligner via cone beam CT (CBCT) and Dolphin software.
METHODS
Twenty cases of mandibular molars with clear aligner were included according to the inclusion and exclusion criteria. CBCT was taken before treatment (T0) and when the first molar was moved in place (T1). Dolphin software was used to measure the effectiveness of molar distalization. Three-dimensional changes in direction and the impact on the incisors and facial soft and hard tissues were evaluated.
RESULTS
The effective rates of crown and root distalization of the second and first mandibular molars were 74%, 49%, and 71%, 47%, respectively. The second and first molars were both the distal buccal cusp with the largest distalization [(2.15 ± 0.91) mm and (1.85±1.09) mm], respectively, with significant difference between the T0 and T1 (<0.05). The second and first molars were accompanied by depression, distal tilt, and buccal tilt with 1.06 mm, 2.10°, 2.27°, and 0.91 mm, 1.62°, and 1.91°, respectively, with significant differences between the T0 and T1 (all <0.05). There was no obvious difference between men and women. The mandibular central incisor showed a lip-side movement of 1.02 mm, a depression of 0.82 mm, a mesial incline of 0.66°, and a crown-lip torque of 1.51° after molar distalization, with significant differences between the T0 and T1 (all <0.001). Only the lower lip thickness increased by 0.1 cm, the length of the lower lip increased by 0.1 cm, and the ANS-ME (distance from anterior nasal spine to submental point) decreased by 0.13 cm, with significant differences between the T0 and T1 (all <0.05).
CONCLUSIONS
Clear aligner can effectively move mandibular molars farther, the crown is more effective than the root, and it is tilted. The second mandibular molar is more effective than the first mandibular molar in its distant displacement and three-dimensional changes. Molar distalization causes minor changes in mandibular incisors and facial soft and hard tissues.
Topics: Cephalometry; Maxilla; Molar; Orthodontic Appliances, Removable; Tooth Movement Techniques
PubMed: 34911842
DOI: 10.11817/j.issn.1672-7347.2021.200391 -
BMC Oral Health Dec 2022The effects of upper-molar distalization using clear aligners in combination with Class II elastics for anchorage reinforcement have not been fully investigated yet. The...
INTRODUCTION
The effects of upper-molar distalization using clear aligners in combination with Class II elastics for anchorage reinforcement have not been fully investigated yet. The objective of this study is to analyze the movement and stress of the whole dentition and further explore guidelines for the selection of traction methods.
METHODS
Three-dimensional (3D) finite element models are established to simulate the sequential molar distalization process, including the initial distalization of the 2 molar (Set I) and the initial distalization of the 1 molar (Set II). Each group set features three models: a control model without Class II elastics (model A), Class II elastics attached to the tooth by buttons (model B), and Class II elastics attached to the aligner by precision cutting (model C). The 3D displacements, proclination angles, periodontal ligament (PDL) hydrostatic stress and alveolar bone von Mises stress in the anterior area are recorded.
RESULTS
In all of the models, the maxillary anterior teeth are labial and mesial proclined, whereas the distal moving molars exhibit distal buccal inclination with an extrusion tendency. With the combination of Class II elastics, the anchorage was effectively reinforced; model C demonstrates superior anchorage reinforcement with lower stress distribution in comparison with model B. The upper canines in model B present an extrusion tendency. Meanwhile, the mandibular dentition in models B and C experience undesired movement tendencies with little discrepancy from each other.
CONCLUSIONS
Class II elastics are generally effective for anchorage reinforcement as the upper-molar distalization is performed with clear aligners. Class II elastics attached to an aligner by precision cutting is a superior alternative for maxillary anchorage control in cases that the proclination of upper incisors and extrusion of upper canines are unwanted.
Topics: Finite Element Analysis; Molar; Incisor; Periodontal Ligament; Orthodontic Appliances, Removable
PubMed: 36456944
DOI: 10.1186/s12903-022-02526-2 -
Progress in Orthodontics 2016The aim of the present study was to test the hypothesis that bodily maxillary molar distalization was not achievable in aligner orthodontics.
BACKGROUND
The aim of the present study was to test the hypothesis that bodily maxillary molar distalization was not achievable in aligner orthodontics.
METHODS
Forty lateral cephalograms obtained from 20 non-growing subjects (9 male, 11 female; average age 29.73 years) (group S), who underwent bilateral distalization of their maxillary dentition with Invisalign aligners (Align Technology, Inc., San José, CA, USA), were considered for the study. Skeletal class I or class II malocclusion and a bilateral end-to-end class II molar relationship were the main inclusion criteria. Cephalograms were taken at two time points: (T0) pretreatment and (T2) post-treatment. Treatment changes were evaluated between the time points using 39 variables by means of paired t test. The level of significance was set at P < 0.05. Reproducibility of measurements was assessed by the intraclass correlation coefficient (ICC).
RESULTS
The mean treatment time was 24.3 ± 4.2 months. At the post-treatment point, the first molar moved distally 2.25 mm without significant tipping (P = 0.27) and vertical movements (P = 0.43). The second molar distalization was 2.52 mm without significant tipping (P = 0.056) and vertical movements (P = 0.25). No significant movements were detected on the lower arch. SN^GoGn and SPP^GoGn angles showed no significant differences between pre- and post-treatment cephalograms (P = 0.22 and P = 0.85, respectively).
CONCLUSIONS
Aligner therapy in association with composite attachments and class II elastics can distalize maxillary first molars by 2.25 mm without significant tipping and vertical movements of the crown. No changes to the facial height were revealed.
Topics: Adult; Cephalometry; Female; Humans; Male; Molar; Reproducibility of Results; Retrospective Studies
PubMed: 27041551
DOI: 10.1186/s40510-016-0126-0 -
The British Journal of Cardiology 2021Radial artery access has transformed cardiac catheterisation, allowing it to be performed in a daycase setting, saving both hospital beds, and nursing care costs....
Radial artery access has transformed cardiac catheterisation, allowing it to be performed in a daycase setting, saving both hospital beds, and nursing care costs. However, there are two common and seemingly diametrically opposite complications. These are radial artery occlusion and forearm haematoma; the former could be reduced by heparin, but at the expense of precipitating the latter. These complications increase proportionally to the size of radial artery sheath used. Interestingly, by cannulating the radial artery more distally beyond its bifurcation in the hand, the distal radial approach appears to be the 'one stone, two birds' or the synchronous Chinese idiom, 'yīshí'èrniăo's' solution, reducing both complications at the same time. Extending this further and downsizing to a 4Fr catheter system, heparin use could be spared altogether, without complications, and haemostasis achieved with short manual pressure at the puncture site. Hence, further cost savings by foregoing commercial compression bands, and abolishing access site care for nurses. We illustrate the above strategy in a patient with challenging radial anatomy, made simple and easy.
PubMed: 35747702
DOI: 10.5837/bjc.2021.039