Root Displacement Research Articles

Q-Switched Neodymium-YAG Laser Angle Surgery in Open-angle Glaucoma

In a short-term pilot study, we evaluated Q-switched neodymium-YAG laser angle surgery in 25 eyes from 22 patients with medically uncontrolled open-angle glaucoma. All eyes had unacceptable intraocular pressures (IOPs), despite maximum tolerated medical therapy, argon laser trabeculoplasty, and prior intraocular filtration surgery (eight eyes). Using a pulse energy of 10 millijoules, ten spots were placed approximately 4 degrees apart in the mid-trabecular meshwork using an Nd-YAG laser (Coherent 9900). The mean preoperative and final postoperative IOPs were 30 +/- 6 mm Hg and 21 +/- 8 mm Hg, respectively. The mean follow-up time was five (+/- 3) months (range, two to 14 months). The final postoperative IOP was less than 22 mm Hg in 17 eyes (68%). Holes within the trabecular meshwork were visible in 14 eyes, and laser therapy was associated with the liberation of debris into the anterior chamber in all eyes. Complications included transient postoperative IOP elevation (eight eyes), angle bleeding (six eyes), and posterior displacement of the iris root (four eyes).

A dental root in the ostium of the maxillary antrum

Displacement of dental roots into the maxillary antrum during the attempted extraction of teeth is not an uncommon occurrence. Their subsequent discharge from the antrum into the nose is a recognised possibility. A case is reported of a dental root so displaced and found at operation to be in the ostium of the maxillary antrum, and it is speculated as to how it arrived there.

Extracapsular Cataract Extraction and Pseudophakos Implantation in Primates: A Clinico-Pathologic Study

Eighteen rhesus monkeys underwent lens implantation with Choyce Mark VIII, Binkhorst iridocapsular, or Shearing posterior chamber lenses. They were sacrificed 4-28 months postoperative. The eyes were compared clinically and histologically. Controls included unoperated eyes and eyes with lens extraction without implantation. Several histologic findings pertained equally to cataract extraction with or without lens implantation. Late opacification of the posterior capsule was caused by migrations and fibrous metaplasia of the lens epithelial cells. These cells appeared to undergo such metaplasia only when exposed directly to aqueous, never when they were in firm apposition to another tissue such as another layer of capsular epithelium, lens cortex, or iris. All implants were well tolerated clinically. Histologically the eyes with Binkhorst lenses showed a tendency to focal loss of iris pigment epithelium and some pigmented macrophages in the iris stroma an trabecular mesh. The Choyce lenses frequently displayed marked displacement and thinning of the iris root, and occasionally showed a few chronic inflammatory cells and thin fibrous encapsulation around the implant feet. The Shearing lenses had no effect on the adjacent ciliary body when the loops were well seated in the lens capsule, but when a loop was anterior to the capsule, it eroded into the ciliary body. The loops developed a thin fibrous capsule within the ciliary body with very little chronic inflammatory reaction. The long-term effect of such loops lying in the ciliary body is undetermined, however. At present it is recommended that, if such a lens is implanted, every effort be made to ensure both loops lie in the capsular envelope. On the basis of this study, it is also recommended that in removing such a lens, one must assume that a loop might lie embedded in the ciliary body and cut the lens free from the loops before removing it.

Compensation of frequency‐dependent amplifier non‐idealities in tunable RC‐active networks

AbstractA structure‐independent synthesis procedure for RC‐active networks, which performs the synthesis process by successive matrix expansion steps, allows the straightforward realization of networks with arbitrary tunable parameters. Since the desired behaviour of the realized circuit may be strongly affected by the frequency‐dependent imperfections of the active devices used for practical circuit construction, a compensation of the resulting root displacements of the network's characteristic equation is needed.The particular properties of the synthesis technique lead to an immediate relation between the root displacement caused by a single matrix transformation step and the information being available when this step is executed. Following a brief description of the synthesis process, this relation is derived and then used to establish a compensating circuitry which has to be added to the synthesized network structure in order to achieve the compensation effect required above.

Significance of tortuous filling defects at lumbar myelography.

At lumbar myelography, tortuous filling defects frequently occur in the presence of a marked local narrowing of the spinal canal. This may lead to a displacement and compression of nerve roots, which may partially or completely fill the subarachnoid space. However, truly elongated nerve roots have also been observed, both at myelography and at operation. Such elongation appears to be a congenital malformation. The recognition of the true nature of tortuous filling defects is important with regard to differentiation against arteriovenous malformations and congested veins.

Effect of Notch Acuity on Critical COD with COD Bend Test Specimens

The conventional COD bend tests are frequently used for the purpose of obtaining a critical COD (δc). But it is well known that δc shows various values depending on notch acuities. Accordingly, COD bend test specimens have usually a fatigue notch. However the industrial material tests are desired to be simple. In this sense, it is desirable that COD bend test specimens have only machined notch.In this paper, the transformation equations of a mouth COD (Vtotal) for a machined notch to δc for a fatigue notch are proposed by considering the machined notch root displacement. These transformation equations are expressed as follows :δ= O.45 (W-a) /0.45W+0.55a+Z [(Vtotal-Ve) -V'] … (Vtotal-Ve≥2V')O.45 (W-a) /0.45W+0.55a+Z [(Vtotal-Ve) 2/4V'] … (Vtotal-Ve<2V')Ve= 0.8d0.3 … (Vtotal≥4V'){0.8d0.3-0.74d0.45 (1-Vtotal/4V')} Vtotal… (Vtotal<4V')whereV'=γσYW (1-v2) /E : limit elastic clip gauge COD defined by Wells, W : specimen width, a : crack depth, Z : distance from free surface to positions setting a clip gauge, d : initial notch root width (d≤0.4mm)The above proposed equations are obtained from results of F. E. M. analysis, and it was confirmed that the relation between δ by the above equations and the plastic zone size is not different in the case of various notch acuities of the specimens. These equations are engineeringly satisfactory in the range of d≤0.4 mm for various materials.

An unusual case of lingual displacement of a mandibular third molar root apex

A complication of mandibular third molar surgery is reported in which lingual displacement of a third molar root occurred in association with the presence of a natural perforation of the lingual plate. The displacement was aggravated by the insertion of mylohyoid muscle fibers into the root itself. Histologic evidence is presented to support the finding of this unusual tissue relationship.

The tooth root within the maxillary sinus.

Abstract— Histological observations in three cases of tooth root displacement to the maxillary sinus show that under certain conditions the root may be accepted by the tissues. General and local factors in the defenco mechanism and the existence or otherwise of periapical pathosis must be considered in determining the treatment.

New definition of multiple-root sensitivity

The sensitivity of a simple root of a polynominal is finite and well defined. For a multiple root, however, the existing definition becomes infinite, even when the root displacements remain finite. In this letter, a well behaved function is proposed to define a multiple-root sensitivity. It is also shown that the new definition, which degenerates to the conventional definition under a special condition, is a meaningful measure of actual root displacements.

Frequency of oro-antral fistulae after perforation to the maxillary sinus.

Abstract— The frequency of oro‐antral fistulae after perforations to the maxillary sinus by extraction of teeth or displacement of roots into the maxillary sinus is investigated. The material comprises 116 patients with a sinus perforation during the period 1950 to 1967. No patients had maxillary sinusitis in relation to the extraction. 104 patients (90 %) were followed‐up two months or more after treatment. In nine cases of sinus perforation without root displacement, no treatment was instituted and seven (78 %) formed an oro‐antral fistula. In 82 cases a primary suture over the perforation was used, resulting in an oro‐antral fistula in six (7 %). In the 13 cases of root displacement into the maxillary sinus, the root was removed and there was a primary suture over the perforation; in three cases (23 %) an oro‐antral fistula was formed. Apparently the usual primary treatment does not prevent oro‐antral fistulae, but the frequency will be less. After treatment of displaced roots, the frequency of oro‐antral fistulae is higher than after treatment of simple sinus perforations. Different methods for closure of sinus perforations are discussed.

The point of maximum intensity of aortic diastolic regurgitant murmur. With special reference to the "right-sided" aortic diastolic murmur.

The point of maximum intensity (PMI) of the aortic diastolic murmur was analyzed in 801 cases of aortic insufficiency (AI) of various etiology, and unusual location including the right-sided murmur was investigated.Though the PMI was widely distributed, a great majority of cases had the PMI along the left sternal border irrespective of the etiology concerned. Particularly, the 3rd and the 4th left sternal border (3L and 4L) were the main places where the murmur was best audible and this was observed in 598 out of 801 cases (74.5%). Mid-sternal portion (3M) was the secondary place and 99 cases (12.5%) had the PMI here.Rather infrequent PMI was along the right sternal border (58 cases ; 7.1%) and around the cardiac apex (21 cases ; 2.5%). The other PMI was exceptional.The right-sided AI murmur was observed predominantly in syphilitic case (27 out of 58 cases ; 47%). However, almost all of the other etiological entity could have the PMI along the right sternal border even in a few cases of rheumatic etiology. Moreover, the syphilitic cases did not always have the PMI along the right sternal border, and it was located on the left side in about a half of cases.The right-sided AI murmur was usually loud enough to permit the wide transmission of the murmur over the precordium. The PMI was located more frequently in the classical aortic area (the 2nd right sternal border ; 2R: 36 cases ; 61%) rather than in the 3rd right sternal border (3R: 18 cases ; 28%), and it was located even in the 1st right sternal border (1R: one case). The cases with the PMI in the upper right sternal border (1R and 2R) usually had louder murmur in 3R than in 3L, but the exception was observed in some cases (4 cases ; 11%). Therefore, the concept of the right-sided AI murmur was revised to include all of the cases which have the PMI along the right sternal border irrespective of the interspaces questioned.Roentgenograms revealed the dilatation of the ascending aorta and the rightward displacement of the aortic root in all cases with the right-sided murmur. However, in cases with the PMI in 2R the elongation of the aorta predominated, whereas the rightward displacement of the aortic root was dominantly observed in cases with the PMI in 3R. The height of the diaphragm was the one of the accessory factors influencing the site of the PMI. In addition, all cases with the right-sided murmur had marked left ventricular enlargement, which also contributed to the rightward shift of the PMI. The conclusion was made that these roent-genographic abnormalities have the primary importance to the right-sided murmur rather than the etiology concerned.Because of the lack of the exact auscultatory and phonocardiographic description, aortic insufficiency associated with aortitis syndrome in the Orient was analyzed and discussed in detail.

Pathogenesis of primary shallow chamber angle closure glaucoma.

The intraocular pressure is the force required to maintain aqueous flow. Normally it varies with the rate of aqueous formation and the resistance to outflow encountered at the trabecular meshwork. Additional outflow resistance may occur from various pathologic closures of the chamber angle including anterior displacement of the iris root. In primary angle closure glaucoma, the iris root is displaced forward without apparent cause, and the angle closure is usually associated with shallowing of the anterior chamber. This discussion is concerned solely with the pathogenesis of primary angle closure glaucoma associated with a shallow anterior chamber. <h3>Clinical Features</h3> Clinically, this disease appears to be acquired since it almost always occurs after the fourth decade. It is characterized by a slow progressive shallowing of the anterior chamber which may antedate by several years rise in intraocular pressure. The pressure rise may be explosive, indicating that critical closure of the angle can

Nonextraction treatment in growing patients, with emphasis on distal movement

The following points have been mentioned: 1. 1. Considerable space can be obtained by distal tipping of tipped-forward lower buccal teeth. 2. 2. It is possible to tip lower buccal teeth distally and have them upright with roots distal to where they had previously been. 3. 3. In properly treated cases, tipped-back lower molars will be uprighted in function by the forces of occlusion, with the roots going distally more than the crown moves forward. 4. 4. When a tip-back force is exerted by an arch wire, there must be a constant distal force to avoid anterior displacement of roots. 5. 5. In many crowded cases, it is not uncommon to discover that the lower molars are tipped mesially. 6. 6. When it is anticipated that Class II elastics will be used, it is very desirable that they be preceded by Class III elastics to prevent anterior cant of the occlusal plane. 5 7. 7. In deficiency cases with low ANB angles, we must be careful not to move point A distally with lingual root torque while at the same time attempting to make room for teeth in the lower arch. 8. 8. A stable upper arch exerts a restraining influence on tipped-back lower teeth being uprighted by the forces of occlusion. 9. 9. A mesial drift of molars is not inevitable in transition from a mixed to a permanent dentition. 10. 10. Lower teeth can be mechanically moved distally through the “leeway” space with likelihood of their staying there. 11. 11. The anterior-posterior position of the lower incisors in stable cases is one of the most permanent of all tooth positions. 12. 12. Lateral expansion of the second molar position causes very little increase in arch length. The amount of increase of the inside measurement 1 is not the same as the increase at the contact point. 13. 13. The basic limitations of treatment should always be respected in treatment planning.