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At least 631 records · Page 35Linked to original sources
PubMed1997

Occlusal migration of the maxillary first primary molars subsequent to the loss of antagonists.

The purpose of this study was to observe the vertical changes in unopposed maxillary first primary molars longitudinally. The subjects of this study were 17 children whose lower first primary molars had to be extracted. Space closure were prevented by crown-loop space maintainers for all these children. Plaster casts were made every 4 months for 16 to 24 months after the extraction. These series of casts were standardized, and vertical changes of the maxillary first primary molars against the occlusal plane were measured using a micro-reader. The mean changes indicated that maxillary first primary molars without intercuspidation tend to drift toward the extraction space. On the control side with antagonists, the maxillary first molars seemed to move reversed to apical throughout the observation period. Accordingly, the results of this study showed new trends after the premature loss of primary molars. The vertical changes toward extraction space varied from -0.40 mm to 1.43 mm at the 16 months after extraction. Mean changes were small, but there were some individual differences in reaction, giving negative values. However, we should always be concerned about loss of arch length and also occlusal drift of unopposed teeth, because the vertical changes were greater than 1 mm at 16 months after extraction in some cases.

Child↗
PubMed1996

Completely submerged primary molars.

Two mixed dentition cases have been presented which became quite complicated because of ankylosed and submerged primary second molars. These cases demonstrate the need for an early orthodontic evaluation and interceptive orthodontics. The orthodontic and surgical procedures required for these two patients could have easily been avoided by removing the ankylosed primary molars and placing space maintainers. (Of course this depends upon the parents responding to their dental recall notices.) If a submerging primary molar is retained too long, the second premolar may become displaced superiorly and the permanent first molar may migrate mesially as it erupts. Both of these problems can be prevented by extracting the ankylosed primary second molar before it submerges below the mesial height of contour of the permanent first molar. A fixed space maintainer then becomes necessary to prevent loss of arch length by mesial migration of the permanent molar.

Ankylosis↗
PubMedDate not supplied

Extractions in support of orthodontic treatment.

Extractions in support of orthodontic therapy may be done in any combination of teeth. The more common extraction patterns are: 1. Maxillary and mandibular first premolars; 2. Maxillary first and mandibular second premolars; 3. Maxillary and mandibular second premolars; 4. Maxillary first premolar; 5. Maxillary second permanent molar; 6. Maxillary first permanent molars; 7. Maxillary permanent lateral incisors; 8. Mandibular permanent incisors; or 9. Any possible combination and variation for other considerations. Extractions have been proven to support changes in the profile, helping in the alignment of teeth and in reducing lower facial height. The decision as to whether or not to extract requires a great deal of thoughtful application of diagnostic skills.

Bicuspid↗
PubMed1998

Loss of space and dental arch length after the loss of the lower first primary molar: a longitudinal study.

The premature loss of primary teeth may harm the normal occlusal development, although there are debates relating to the necessity of using space maintainer appliances. The aim of the study is to evaluate the changes in the dental arch perimeter and the space reduction after the premature loss of the lower first primary molar in the mixed dentition stage. The sample consists of 4 lower arch plaster models of 31 patients, within the period of pre-extraction, 6, 12 and 18 months after the lower first primary molar extraction. A reduction of space was of noted with the cuspid dislocation and the permanent incisors moving toward the space of the extraction site. It was concluded that the lower first molar primary premature loss, during the mixed dentition, implicates an immediate placement of a space maintainer.

Child↗
PubMedDate not supplied

The longevity of space maintainers: a retrospective study.

METHODS: This retrospective study investigated the longevity of 301 space maintainers fitted in 141 patients aged 3.4-22.1 years in the Department of Pediatric Dentistry at Leeds Dental Institute between 1991 and 1995. RESULTS: Failure occurred in 190 space maintainers (63%), of which 36% were due to cement loss, 24% breakage, 10% design problems, and 9% were lost. Using the life table method, the median survival time (MST) for space maintainers was found to be 7 months. Band and loop (B&L) appliances had the highest MST of 13 months, while the lower lingual holding arch (LLHA) had the lowest of 4 months. Unilateral space maintainers survived longer than bilateral space maintainers (MST of 13 months vs. 5 months). Left B&Ls had a MST of 16 months, compared to only 4 months for right B&Ls, Gender, age, arch in which the appliance was placed, the operator planning it, fixed vs. removable, and adequacy of pretreatment assessment did not have a significant effect on survival time.

Adolescent↗
PubMed1994

Expanded polytetrafluoroethylene titanium-reinforced membranes for regeneration of mucogingival recession defects. A 12-case report.

The regeneration of tissue to treat mucogingival recession defects is well established but these defects pose additional challenges for the clinician in the creation and maintenance of a space under the guiding membrane. We used titanium-reinforced membranes of expanded polytetrafluoroethylene (ePTFE) to facilitate the creation and maintenance of such spaces in 12 patients with mucogingival recession defects. The membranes were judged according to their ease of handling and placement and the regenerative results; the patients were evaluated for gingival recession and the quantity of attached gingiva before and for as long as 15 months after treatment. At 15 months, the average gingival recession was 1.4 mm (pretreatment = 5.3 mm), and the attached gingiva measured 3.3 mm (pretreatment = 1.4 mm). Titanium-reinforced ePTFE membranes result in a simpler, faster, and more predictable surgical procedure. Comparison of titanium-reinforced ePTFE membranes to other available procedures awaits assessment in clinical trials.

Adolescent↗
PubMed1984

Immunocytochemical studies of quaking mice support a role for the myelin-associated glycoprotein in forming and maintaining the periaxonal space and periaxonal cytoplasmic collar of myelinating Schwann cells.

The myelin-associated glycoprotein (MAG) is an integral membrane glycoprotein that is located in the periaxonal membrane of myelin-forming Schwann cells. On the basis of this localization, it has been hypothesized that MAG plays a structural role in (a) forming and maintaining contact between myelinating Schwann cells and the axon (the 12-14-nm periaxonal space) and (b) maintaining the Schwann cell periaxonal cytoplasmic collar of myelinated fibers. To test this hypothesis, we have determined the immunocytochemical localization of MAG in the L4 ventral roots from 11-mo-old quaking mice. These roots display various stages in the association of remyelinating Schwann cells with axons, and abnormalities including loss of the Schwann cell periaxonal cytoplasmic collar and dilation of the periaxonal space of myelinated fibers. Therefore, this mutant provides distinct opportunities to observe the relationships between MAG and (a) the formation of the periaxonal space during remyelination and (b) the maintenance of the periaxonal space and Schwann cell periaxonal cytoplasmic collar in myelinated fibers. During association of remyelinating Schwann cells and axons, MAG was detected in Schwann cell adaxonal membranes that apposed the axolemma by 12-14 nm. Schwann cell plasma membranes separated from the axolemma by distances greater than 12-14 nm did not react with MAG antiserum. MAG was present in adaxonal Schwann cell membranes that apposed the axolemma by 12-14 nm but only partially surrounded the axon and, therefore, may be actively involved in the ensheathment of axons by remyelinating Schwann cells. To test the dual role of MAG in maintaining the periaxonal space and Schwann cell periaxonal cytoplasmic collar of myelinated fibers, we determined the immunocytochemical localization of MAG in myelinated quaking fibers that displayed pathological alterations of these structures. Where Schwann cell periaxonal membranes were not stained by MAG antiserum, the cytoplasmic side of the periaxonal membrane was "fused" with the cytoplasmic side of the inner compact myelin lamella and formed a major dense line. This loss of MAG and the Schwann cell periaxonal cytoplasmic collar usually resulted in enlargement of the 12-14-nm periaxonal space and ruffling of the apposing axolemma. In myelinated fibers, there was a strict correlation between the presence of MAG in the Schwann cell periaxonal membrane and (a) maintenance of the 12-14-nm periaxonal space, and (b) presence of the Schwann cell periaxonal cytoplasmic collar.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

Transcellular water transport in lung alveolar epithelium through mercury-sensitive water channels.

The movement of water between the air space and capillary compartments is important for the maintenance of air space hydration during respiration and for reabsorption of excess alveolar fluid. We have obtained immunocytochemical and functional evidence that plasma-membrane water channels are responsible for water transport in the intact lung. Northern and quantitative immunoblot analysis showed high expression of CHIP28 (channel-forming integral membrane protein of 28 kDa) water channels in rat lung; immunocytochemistry showed CHIP28 localization to epithelial cell plasma membranes. Stopped-flow light scattering measurements of osmotic water permeability (Pf) in freshly isolated rat alveolar type II epithelial cells indicated a high Pf of 0.015 +/- 0.002 cm/s (10 degrees C) that was weakly temperature-dependent (activation energy, 4 kcal/mol) and reversibly inhibited by 78 +/- 4% by 0.5 mM HgCl2. An in situ-perfused sheep lung model was used to determine the route for water movement in intact lung. Blood-to-air-space water transport was measured by sampling air space fluid after instillation into distal air spaces of hyperosmolar saline (900 mOsm) containing radioiodinated albumin and [14C]mannitol. In seven sets of experiments, air space osmolality and radioiodinated albumin equilibrated with a t1/2 of 0.85 +/- 0.1 min. In the contralateral lung perfused with 0.5 mM HgCl2, t1/2 increased to 2.7 +/- 0.4 min; the inhibitory effect of HgCl2 was fully reversed by 5 mM 2-mercaptoethanol. These results provide direct evidence for transcellular movement of water across the alveolar epithelium in intact lung through mercury-sensitive water channels.

Animals↗
PubMed1997

Ligament reconstruction basal joint arthroplasty without tendon interposition.

The necessity of tendon interposition for the maintenance of joint space after basal joint resection arthroplasty with ligament reconstruction has not been established. A prospective, randomized study was performed. In Group I (nine patients), ligament reconstruction was performed to suspend the first metacarpal in addition to placement of a rolled tendon interposition to fill the void created by resection of the trapezium. In Group II (11 patients), ligament reconstruction alone was performed, with use of a Mitek suture anchor. No tendon interposition was performed. This allowed use of a more limited incision and shorter length of tendon graft. Average followup was 23 months. There was no difference between the two groups in range of motion of the thumb, grip strength, lateral pinch strength, the ability to perform activities of daily living, or subjective satisfaction with the procedure. Two- and three-point pinch strength was statistically significantly greater in Group II. Lateral radiographs of the basal joint at followup, at rest and with pinch, showed maintenance of the joint space, and no difference between the two groups. Tendon interposition is not necessary for maintenance of joint space after basal joint resection arthroplasty if ligament reconstruction is performed.

Activities of Daily Living↗
PubMed1985

Space nursing. A professional challenge.

The challenge is to have man living and working in a permanently based space station. Nursing is on the threshold of expanding the health care role to man's adaptation in outer space. Elements of man's physiologic and psychologic responses are involved in determining the most productive use of man and machines in the space environment. Curricular considerations for a career in space nursing are being explored. The projection of possibilities for practice of space nursing can produce effective contributions toward health care maintenance of the space station personnel. The challenge for nursing is to become a collaborating team participant in the exploration of living and working in space.

Adaptation, Physiological↗
PubMed1995

Use of a titanium-reinforced membrane in periodontal regeneration: a case report.

One of the most important principles of guided tissue regeneration is space creation and maintenance in the early stages of wound healing. Many devices have been tested to provide such space during this stage, some of which include various bone grafts, resorbable pins, and stainless steel fixation screws and tentpoles. A recently developed membrane fulfils such requirements. A case describes the use of this new membrane to treat a combined dehiscence and interproximal osseous defect. This technique was proven to have the potential to eliminate deep osseous defects and allow new attachment of soft tissue on the tooth surface.

Alveolar Bone Loss↗