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At least 19 recordsLinked to original sources
PubMed1991

In vitro measurement and characterization of current density profiles produced by non-recessed, simple recessed, and radially varying recessed stimulating electrodes.

Potential fields induced by nonrecessed, simple recessed, and radially varying recessed electrode designs were measured in vitro. Comparison of experimental results with theoretical analyses substantiated the experimental measurement technique and emphasized the importance of considering both nonuniform charge injection and surface electrochemistry when designing implantable stimulating electrodes. Radially varying recesses produced uniform charge injection at the electrode surface and at the aperture-tissue interface. In general, the radially varying recessed electrodes provided a combination of uniform charge injection and flexibility in design and fabrication that warrants their incorporation into all appropriate planar stimulating electrode designs.

Electric Conductivity↗
PubMed1977

The collicular recess organ: evidence for structural and secretory specialization of the ventricular lining in the collicular recess.

The collicular recess organ and adjacent portions of the collicular recess were studied by light microscopy, scanning electron microscopy and transmission electron microscopy. In the collicular recess, the ventricular wall contains folds and is well vascularized. The adluminal ependymal cells generally bear kinocilia and microvilli on their ventricular surface. Among the cilia, many secretory droplets, some axons, and few supraependymal cells are seen. Various stages of apocrine ependymosecretion are observed. In addition to tanycytes, coelocytes are found scattered throughout the ependymal lining of the collicular recess. Coelocytes, characterized by lumina containing cilia and a few microvilli, are accumulated in ependymal and hypependymal positions of the collicular recess organ at the roof of the collicular recess.

Animals↗
PubMed1976

The possible pathogenesis of gingival recession. A histological study of induced recession in the rat.

Stages in the pathogenesis of gingival recession were observed in rats in which pocketing had been induced by replacement of natural incisors with dental implants. Suitable conditions were thus created on the palatal aspect of the implant sockets for recession to occur. The recession process was examined at intervals by taking transverse serial sections. In the epithelial and connective tissues deep to the receding margin, morphological changes were seen which apparently lead to cleft formation and recession. These appeared to be associated with mononuclear cell infiltration of the connective tissue. The study suggests that gingival recession involves a localized inflammatory process which causes breakdown of connective tissue and leads to proliferation of the epithelium into the site of connective tissue destruction. Proliferation of the epithelial cells into the connective tissue brings about a subsidence of the epithelial surface, which is manifest clinically as recession.

Animals↗
PubMed1988

Comparison of hang-back medial rectus recession with conventional recession.

Hang-back recession is commonly used for adjustable strabismus surgery and surgery for dissociated vertical deviation. The authors have begun to use the hand-back technique for routine recessions as well, to simplify the procedure and to lessen the risk of scleral perforation. In 49 consecutive children undergoing conventional bilateral medial rectus recession and 31 consecutive children undergoing hang-back recession, the success rate (+/- 10 prism diopters [PD]) was 80% in the conventional group and 74% in the hang-back group at 6 weeks. The dose-response curves were nearly identical. These results confirm that hang-back recessions for infantile and acquired esotropia are a predictable alternative to conventional strabismus surgery.

Child↗
PubMed1986

The estimation of risks from the induction of recessive mutations after exposure to ionising radiation.

Since recent assessments of genetic risks from radiation have concentrated on harmful dominant effects, a quantitative assessment of risks from recessives is needed. Presumably, harmful recessives can arise at all loci coding for essential proteins (perhaps 10 000), but mutation to dominant alleles is likely to be a property of relatively few loci. While many recessives doubtless remain to be discovered, those known at present tend to have earlier and more severe effects than dominants. Induced recessive mutations can cause harm by partnership with a defective allele already established in the population; partnership with another recessive mutation induced at the same locus; the formation of homozygous descendants, that is, identity by descent; and heterozygous effects. Calculations based on a combination of data from observations on human populations and from mouse experiments suggest that an extra genetically significant dose of 1 cGy (centiGray, equivalent to 1 rad) X or gamma irradiation received by each parent in a stable population with a million liveborn offspring would induce up to 1200 extra recessive mutations. From partnership effects, about one extra case of recessive disease would be expected in the following 10 generations. Homozygosity resulting from identity by descent could not normally occur until the fourth generation after exposure but, on certain assumptions, about ten extra cases of recessive disease would be expected from this cause by the tenth generation. In the same period, about 250 recessive alleles would be eliminated in heterozygotes (that is, Muller's 'genetic deaths') given 2.5% heterozygous disadvantage. These deleterious heterozygous effects should not be combined with those of dominants, as has been done in some previous risk estimates. It is considered unlikely that many radiation induced recessives would show heterozygous advantage. Certain dominants (combined frequently at least 10(-3)) should be excluded from calculations of mutational risk because they are unlikely to be maintained by mutation.

Abnormalities, Radiation-Induced↗
PubMed1989

Occurrence of gingival recession in adults.

The occurrence of gingival recession was investigated in adults by age and gender and in relation to their dental status and frequency of toothbrushing. A total of 258 dentate subjects were clinically examined. Their mean age was 46 years and they had an average of 19.4 natural teeth. Gingival recession was recorded as present if any root surface was clearly visible without retraction of the gingival tissue. Recession was found on at least one tooth surface in 68% of subjects. Mean number of surfaces with recession was 7.2 for women and 10.4 for men. Subjects with gingival recession had fewer natural teeth than did those without recession. The two groups did not differ from each other in the number of filled teeth and decayed teeth. Mandibular teeth had more surfaces with recession than did maxillary ones. Sites of recession occurred quite symmetrically. Frequent toothbrushers had, both in the maxilla and mandible, more surfaces with recession than had those brushing their teeth infrequently. Frequent toothbrushing had a greater association with recession among women and in the youngest age group.

Adult↗
PubMed1991

Development of a system to assess visible and hidden gingival recession.

The accurate assessment of gingival recession is important because of soft tissue deterioration and/or the state of soft tissue health. While recession of the gingival margin is a common and important symptom of periodontal disease, it also refers to the location of the gingiva and not to its condition. Recession can occur at all tooth surfaces. This paper describes a new system designed to measure two parameters of gingival recession. One parameter of recession is visible above the gumline to an observer, while another parameter is hidden by the gingiva itself. Visible recession is the shift of the marginal gingiva to a position apical to the cemento-enamel junction. Hidden recession is obscured by gingiva and can be assessed by measuring from the free gingival margin to the level of epithelial attachment. The system developed here differs from the current indices commonly used for gingival recession, since it combines both the visual portion with the hidden portion of recession for a total score. The assessment method is similar to the calculus scoring procedure of Volpe and Manhold and is called the Gingival Recession Total (GRT) scoring system.

Gingival Recession↗
PubMed1992

The natural history of periodontal disease in man: prevalence, severity, and extent of gingival recession.

This paper describes the occurrence and levels of gingival recession in 2 cohorts of individuals participating in parallel longitudinal studies in Norway (1969-1988) and Sri Lanka (1970-1990), covering the age range from 15 to 50 years. In the Norwegian cohort gingival recession had begun early in life. It occurred in greater than or equal to 60% of the 20 year-olds and was confined to the buccal surfaces. At 30, greater than or equal to 70% had recession, which still was found mainly on buccal surfaces. As the group approached 50 years of age, more than 90% had gingival recession; greater than or equal to 25% of the buccal surfaces were involved, greater than or equal to 15% of lingual, and 3 to 4% of the interproximal surfaces. In the Sri Lankan cohort greater than or equal to 30% exhibited gingival recession before the age of 20 years. By 30 years, 90% had recession on buccal, lingual, and interproximal surfaces; and at 40 years, 100% of the Sri Lankans had recession. As they approached 50 years, gingival recession occurred in greater than or equal to 70% of the buccal, greater than or equal to 50% of the lingual, and 40% of the interproximal surfaces. Based on the special features of the two cohorts, the working hypothesis is advanced that there is more than one type of gingival recession and probably several factors determining the initiation and development of these lesions.

Age Factors↗
PubMed1989

Hypohidrotic ectodermal dysplasia: argument against an autosomal recessive form clinically indistinguishable from X-linked hypohidrotic ectodermal dysplasia (Christ-Siemens-Touraine syndrome)

Hypohidrotic ectodermal dysplasia (HED) is a well-described, X-linked recessive disorder characterized by hypohidrosis, hypodontia, and hypotrichosis in males. Reports of similarly affected females have suggested autosomal recessive inheritance in some families. The evidence for two clinically identical but genetically distinct disorders is not convincing, however. In two families with X-linked recessive inheritance of HED, the condition was severe in females. A critical review of previously reported cases of presumed autosomal recessive HED suggests that an autosomal recessive form of the condition identical to the X-linked HED may not exist. All sporadic instances of females with classic HED should be considered to be X-linked recessive, and counseling for X-linked recessive inheritance as well as autosomal recessive inheritance should be given.

Anodontia↗
PubMed1986

Gingival recession in schoolchildren at 7, 12 and 17 years of age in Espoo, Finland.

The present study was undertaken in response to a growing concern among clinicians about an increase in gingival recession among children and adolescents. Groups of 50 boys and 50 girls aged respectively 7, 12, and 17 yr were examined at Espoo Health Centre in 1983. Gingival recession was measured on the facial and lingual aspects of all permanent teeth. Whenever the gingival margin was located on root cementum, the distance from the gingival margin to the enamel border was measured to the nearest 0.5 mm. Recession was categorized as "slight" (0.5 or 1 mm) or "extensive" (1.5-3.5 mm). The prevalence of gingival recession was 5% at 7 yr, 39% at 12 yr, and 74% at 17 yr of age. More girls than boys had recession in the two youngest age groups. At 17 yr recession was equally common in both sexes and both "slight" and "extensive" recession was most often recorded on facial surfaces of first molars, premolars and canines. The alarmingly high prevalence of gingival recession at young age warrants further study of both the reasons and the consequences of early cementum exposure.

Adolescent↗
PubMed1985

Recessive mutations from natural populations of Neurospora crassa that are expressed in the sexual diplophase.

Wild-collected isolates of Neurospora crassa Shear and Dodge were systematically examined for recessive mutations affecting the sexual phase of the life cycle, which is essentially diploid. Seventy-four of 99 wild-collected isolates from 26 populations in the United States, India and Pakistan carried one or more recessive mutations that reduced fertility significantly when homozygous; mutations affecting spore morphology were also detected. Limited complementation tests indicate that most of the 106 recovered mutations are unique.--The recessive diplophase (= sexual phase) mutations were uncovered by crossing each wild-collected isolate to a marked two-chromosome double-reciprocal translocation strain as "balancer." Surviving progeny receive approximately 60% of their genome from the wild parent, but receive the mating-type allele from the "balancer" parent. These progeny were backcrossed to the wild parent and were also crossed with a standard laboratory strain (fl). Reduced fertility in the backcross vs. normal fertility in the cross with the laboratory standard signals the presence of a recessive mutation in the wild-collected isolate.--Most of the mutants (95 of 106) fall into two major classes: those producing barren perithecia with no or few viable ascospores (51) and those with spore maturation defects (44). Most of the recessive barrens result either from an early block in meiosis of ascus development (25) or from a late disturbance in postmeiotic ascus behavior (18).--These recessive mutations are formally equivalent to recessive lethals in higher eukaryotes and may be important in determining the breeding structure of natural Neurospora populations.

Crosses, Genetic↗
PubMed1991

The association between supragingival [correction of subgingival] calculus deposits and the extent of gingival recession in a sample of Thai children and teenagers.

A survey was performed on a sample of children and teenagers in Thailand. The sample consisted of 260 subjects ages 10-17 years. Assessments of the prevalence and amount of supragingival calculus (Volpe-Manhold) on the facial and lingual surfaces of the six mandibular anterior teeth were recorded. All subjects then received a thorough whole mouth prophylaxis. Two weeks later they were reexamined for gingival recession using the Gingival Recession Total (GRT) scoring system on the same six mandibular anterior teeth. For the analysis, the calculus scores were used to categorize the subjects as having slight, medium, or heavy calculus. Using the GRT scores, the same subjects were then categorized as having mild, moderate or extensive gingival recession. The categories of both calculus level and gingival recession level were statistically assessed using the Chi-square distribution and a significant difference was found indicating that the amount of calculus was related to total gingival recession. Subjects with slight calculus had more mild recession whereas medium or heavy calculus formers had more moderate or extensive total gingival recession scores.

Adolescent↗
PubMed1991

[Treatment of gingival recession with a coronally repositioned flap].

The treatment of an exposed root surface may be indicated for an aesthetic improvement of a gingival recession. The surgical technic depends on the type of the recession, the quality and the quantity of the keratinized gingiva apically or laterally from the recession. The purpose of this study is to evaluate the minimal quantity of keratinized gingiva necessary to obtain a root coverage. 10 recessions on maxillary cuspids were treated with coronally repositioned flap. Less than 3 mm of keratinized gingiva was present apically to the exposed root surface. All patients received oral hygiene instructions, plaque control and scaling and root planing. Gingival recession, width of keratinized gingiva and loss of attachment were measured at the time of surgery and three months postoperatively. The mean recession was 5.20 mm (+/- SE = 0.36) prior to treatment and the keratinized gingiva was 1.70 mm (+/- 0.16) high at T0. The mean gain of root coverage was 3.43 mm (+/- 0.29) at three months post-operatively. At T0 and 3 months post-operatively, the measures of recessions showed a statistically difference confirming the validity of the technic. The absence of correlation between initial height of keratinized gingiva and the coverage result (r = 0.05) indicates that initial width of keratinized gingiva does not affect the coverage results.

Epithelial Attachment↗
PubMed1991

Grafted and ungrafted labial gingival recession in pediatric orthodontic patients: effects of retraction and inflammation.

The purpose of this retrospective study was to determine changes in recession and other periodontal factors after orthodontic treatment of malocclusions. Twenty patients with preorthodontic labial recession on one or more mandibular central incisors were studied. Ten patients had received autogenous gingival grafts in the area of recession prior to orthodontics, while ten received no graft. The teeth presenting recession had been retruded from a preorthodontically prominent arch position. Moderate inflammation of marginal tissues and fair-to-poor oral hygiene were maintained by the patients. Statistically significantly less gingival recession was found in both groups after orthodontic treatment than was found pretreatment. The results of this study indicated that labial recession tends to decrease with retrusion of mandibular incisors even when moderate inflammation and fair-to-poor oral hygiene persist. Preorthodontic gingival grafting did not further decrease the postorthodontic gingival recession.

Adolescent↗
PubMed1986

Cross-sectional anatomy of the pericardial sinuses, recesses, and adjacent structures.

Detailed drawings of four cross sections through the mediastinum which pass through the sinuses and recesses of the pericardial cavity, are presented. The drawings depict the location and extent of the pericardial sinuses, recesses, and their closely associated extrapericardial structures. Two previously unnamed recesses within the serous pericardium are defined and named, one the inferior aortic recess of the transverse sinus and the other, the right pulmonic recess of the transverse sinus. The terminology of the pericardial sinuses and recesses has been inconsistent, and the authors propose a nomenclature for standardizing the names of the recesses of the serous pericardium. Important anatomic pericardial relationships with regard to pericardial effusions and lymphadenopathy are discussed.

Diagnosis, Differential↗
PubMed1992

Azygoesophageal recess: normal CT appearance in children.

The azygoesophageal recess is the interface of the subcarinal portion of the mediastinum and the right lower lobe. The configuration of the recess on CT can be used as a sensitive indicator of abnormality in the mediastinum. In normal adults the recess is concave. A convex contour is a normal variant, particularly in young adults. The normal appearance of the azygoesophageal recess in children has not been studied. Accordingly, we reviewed chest CT examinations performed in 253 children ranging from 1 month to 20 years old. Forty patients were excluded from further analysis either because the recess could not be evaluated properly or because underlying disease caused the mediastinum to have an abnormal configuration. An age-related spectrum of normal configurations was observed in the remaining 213 patients. A convex or straight contour was found in 96% of children less than 3 years old. Scans of children 3-12 years old revealed a spectrum of configurations. The typical adult concave configuration was seen in 78% of adolescents more than 12 years old. Overall, in only 90 (42%) of 213 children in this study was a concave recess observed on CT. Our experience shows a convex azygoesophageal recess on CT should be considered the normal configuration in infants and young children. Recognition of this age-related variation is useful in the CT evaluation of the mediastinum in children.

Adolescent↗
PubMed1989

Pathologic findings after recession and resection of extraocular muscles in rabbits.

A study on the pathologic findings after recession and resection of extraocular muscles in rabbits was performed. Fibrosis of the extraocular muscles increased with time, which showed no difference between the recessed and resected muscles. Inflammation and foreign body reaction decreased with time, which showed no difference between the recessed and resected muscles. Adhesions of extraocular muscles to the sclera were observed from one month after the operation. The resected muscles showed milder adhesion to the sclera than the recessed ones. The operated extraocular muscles showed atrophies at one month, which showed no difference between the recessed and resected muscles. According to our results, when reoperation is needed, fibrosis of the extraocular muscles after recession and resection should be considered when making a decision on the amount of muscle to be recessed and resected.

Animals↗