Maximum Retraction Research Articles

Soft tissue changes after upper premolar extraction in Class II camouflage therapy.

The long-term effect on the facial profile has led many orthodontists to attempt Class II division I camouflage treatment without extraction. Practitioners may cite "dishing in the face" as a reason not to extract. Previous investigations have evaluated the soft tissue response after maxillary incisor retraction, but few have evaluated the effect of maximum retraction in skeletal mandibular deficient Class II patients with essentially no crowding. Twenty-seven Class II division I Caucasian patients with a mean of 8.62 mm of overjet, little to no arch length deficiency, and maximum anchorage requirements were treated with extraction of only maxillary first premolars. Pre- and posttreatment lateral cephalograms were taken. Using several skeletal and soft tissue cephalometric measures, the treatment changes were assessed. The mean maxillary incisor retraction was 5.27 mm, the mean maxillary lip retraction was 2.03 mm, and the mean mandibular lip retraction was 1.23 mm. All the patients finished with good overall facial harmony and balance. The maxillary first premolar extraction for orthodontic camouflage may be a viable treatment option, especially if the patient has full upper lips and only a relative mandibular deficiency.

Angular kinematic patterns of limbs in elite and riding horses at trot.

Normal speed videography was used to determine the angular parameters of 28 Spanish Thoroughbreds at trot. Horses were divided into 3 groups: Group UT, comprising 9 animals (provided by the VII National Stud, Cordoba, Spain) which had undergone no specific training programme and which were hand led at the trot; Group T, formed by 19 horses considered to be highly bred and trained, and which were also hand led; and Group RT, comprising the same horses as the latter group but this time trotted by a rider. Each animal was filmed 6 times from the right-hand side, using a Hi8 (25 Hz) video camera. Angular parameters for fore- and hindlimb joints were measured in each stride from computer-grabbed frames and entered into a spreadsheet for calculation; parameters included maximum and minimum angles, range of motion, and angles at landing, lift off and maximum hoof height; the times at which maximum angle, minimum angle, lift off and maximum hoof height occurred were calculated as percentages of total stride duration. Stride velocity (mean [s.d.]) was 4.01 (0.62), 3.60 (0.34) and 3.07 (0.36) m/s for Groups UT, T and RT, respectively. Data were then compared between Groups UT-T and Groups T-RT. Compared with Group UT, horses from Group T featured a shorter stance percentage (P<0.001) in both fore- and hindlimbs. The range of motion in forelimbs was smaller (P<0.05), due to lower retraction (P<0.001); moreover, maximum retraction appeared earlier (P<0.05). Greater scapular inclination was in evidence (P<0.05) and the shoulder joint extended further (P<0.05). Fore- and hind fetlock joints revealed a relatively shorter hyperextension period during the stance phase (P<0.01). Compared with Group T, horses from Group RT had a longer stance percentage, with belated maximum retraction of the fore- and hindlimbs. The range of movement in scapular inclination was greater (P<0.05), due to a smaller minimum angle (P<0.01), and the shoulder joint flexed more (P<0.05). The elbow joint extended more and for longer during the stance phase. Initial extension of the hip joint (P<0.05) and tarsus (P<0.001) lasted longer. The carpal and fore and hind fetlock joints recorded relatively longer hyperextension times, in addition to greater hyperextension during the stance phase. The results from the present study suggest that rider-effect must be taken in consideration when well gaited horses are selected for dressage purposes.

Management of aphakic pupillary block. A new argon-laser approach.

This communication concerns 9 cases of aphakic pupillary block with high intraocular pressure, which were managed successfully by means of a new argon-laser technique. This new approach consisted in the application at the collarette zone of the iris, 1.5 mm from the pupillary border, of a mobile argon-laser beam of variable intensity, ranging from 250 to 500 mW, of constant time (0.5 sec) and of fixed spot size (200 micron m). In some instances the beam was moved parallel and in other cases vertically to the pupillary border in the direction towards the ciliary portion of the iris. This technique ensures maximum retraction of the pupillary border, corresponding to the line of application, coupled with the least possible damage to the iris and a minimum of applications. Simultaneously with the retraction the posterior synechiae of the iris are detached and the outflow of the aqueous trapped in the posterior chamber released.