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Biomedical subjects

R M Watson

Publications and source records attributed to R M Watson.

143 records · Page 8Linked to original sources

Protease activities in peri-implant sulcus fluid from patients with permucosal osseointegrated dental implants. Correlation with clinical parameters.

The 15 patients included in this study each had 2-6 permucosal Branemark osseointegrated implants that had functioned successfully for 18 months or more. They were given a full oral examination which included measurements of probing depth and gingival, bleeding and plaque indices around the implants. Marginal bone reduction during the functional life of the implants was estimated from radiographs. At a separate visit, peri-implant sulcus fluid (PISF) was collected on filter paper strips from the deepest probing site of each implant. PISF volumes were measured and the samples eluted into buffer. Protease activities in the eluates were determined by fluorimetric assay with peptidyl derivatives of 7-amino-4-trifluoromethyl coumarin. Enzyme levels followed the order: cathepsin B/L greater than elastase greater than dipeptidyl peptidase IV greater than trypsin-like activity. Total enzyme activities and concentrations both correlated positively with all clinical parameters in linear regression analysis. This was true on both a patient level using mean patient values and a site level using pooled patient data. Nearly all of the site level correlations were statistically significant, though coefficients were generally higher for total enzyme activities than concentrations. Elastase-like activity gave the best overall correlations of the different proteases measured. Amongst the clinical parameters, correlations were generally best with gingival index and bone reduction. Total enzyme activities had good diagnostic specificity and sensitivity as predictors of clinical parameters and the figures were especially high for elastase-like activity as a marker of bone reduction. PISF proteases may thus be of value in monitoring tissue responses to osseointegrated implants.

Adult↗

Protective effects of fluticasone on allergen-induced airway responses and sputum inflammatory markers.

BACKGROUND: A direct comparison of the protective effects of single and regular doses of inhaled glucocorticoid on allergen-induced asthmatic responses and inflammation has not been made. OBJECTIVE: To compare the effects of pretreatment with fluticasone 250 microg 30 min before allergen inhalation and two weeks of 250 microg twice daily (last dose 24 h before challenge) with single and regular (twice daily) placebo doses on early and late asthmatic responses, induced sputum cell counts and measures of eosinophil activation at 7 h and 24 h, and methacholine airway responsiveness at 24 h. PATIENTS AND METHODS: Ten mild asthmatic patients were studied in a randomized, double-blind, placebo controlled crossover study. RESULTS: Regular fluticasone increased the baseline mean provocative concentration of methacholine to cause a 20% fall (PC20) in forced expiratory volume in 1 s (FEV1) from 2.6 to 6.4 mg/mL (P<0.05) and lowered the eosinophil count from 3.1% to 0.4% (P<0.05) compared with regular placebo. Neither single nor regular fluticasone had any effect on the early asthmatic response. Single fluticasone attenuated the late asthmatic response, the mean +/- SEM maximum percentage fall in FEV1 (10.8+/-3.6 compared with single placebo 18. 8+/-3.5, P=0.03), the allergen-induced increase of airway responsiveness (P<0.05), and the eosinophilia (P<0.005) and activated eosinophils at 7 h (P<0.01) but not at 24 h. Regular fluticasone also attenuated the late asthmatic response (11.1+/-2.5) compared with regular placebo (19.6+/-4.5), but this was not statistically significant and did not protect against the induced increase in airway responsiveness or the sputum eosinophilia. CONCLUSION: Two weeks of regular inhaled fluticasone discontinued 24 h before allergen challenge does not offer any additional protection against the early or late asthmatic responses, increased airway responsiveness or sputum eosinophilia compared with a single dose of 250 microg immediately before allergen challenge, despite increasing baseline PC20 and decreasing sputum eosinophilia prechallenge. The significance of the protective effect of a single dose of inhaled steroid before an allergen inhalation and the duration of the protective effect need further investigation.

Administration, Topical↗

Fabrication of a wax ear by rapid-process modeling using stereolithography.

PURPOSE: The purpose of this article is to describe an automated technique that creates a mirror-image wax model of the contralateral ear using a rapid prototyping technique, which allows precise positioning and adaptation to the deficient side of the face. MATERIALS AND METHODS: Magnetic resonance images (MRI) are taken of the face and then digitized and reformatted into a 3-dimensional image. The image of the normal ear is extracted, mirrored, and positioned onto the image of the deformed side of the face. The digitized data, when used in conjunction with stereolithography, produces a photopolymerized resin model ear. A model wax ear is created by pouring molten wax into a silicone mold of the resin model ear. RESULTS: A model wax ear of identical dimensions, shape, and internal contouring as the contralateral normal ear is created. The technique allows the undersurface of the model wax ear to be precisely positioned against the surface contours of the deformed side of the face in 1 patient. CONCLUSION: The use of stereolithography from MRI scan data is a suitable technique for producing a model wax ear that fits the deformed side of the face. The 3-dimensional computer image of the face may also be used to plan the position (level and protrusion) of the ear.

Computer-Aided Design↗

Considerations in design and fabrication of maxillary implant-supported prostheses.

Principles of the design and fabrication of implant-supported maxillary prostheses are described. The significance of the maxillomandibular relationships, maxillary arch size to the location of the implants, and the positioning of the restored dental arch are discussed. Angulated abutments may overcome conflicts between the position of the artificial teeth and the implants. Solutions to design features that may impair achievement of a pleasing appearance, good gingival health, and well-articulated speech are considered.

Adult↗

The effects of prefabricated bar design on the success of overdentures stabilized by implants.

Two groups of patients were provided with implant-stabilized mandibular overdentures supported by straight ovoid prefabricated bars with a resilient joint or parallel-sided bars with a rigid joint. Measurements of plaque index, mucosal cuff health and height, marginal bone height, pathology of the denture-bearing mucosa, and patient satisfaction were correlated with the different bar designs. Ovoid bars with a resilient joint between the denture and the bar have been shown to give a slightly increased incidence of problems associated with the denture-bearing mucosa. Furthermore, the only significant mean increase in recession of the mucosal cuff was found on the distal surfaces of the distal abutments in this group of patients.

Alveolar Bone Loss↗

Results of treatment of 20 patients with implant-retained auricular prostheses.

A prospective study of 20 patients receiving rehabilitation for a missing external ear revealed the failure of three flanged implants in a total of 60 placed for the support of a prosthesis and 10 for retention of a bone-anchored hearing aid. Factors limiting an optimal outcome were health of the cutaneous cuff around the abutments, bonding of the silicone ear to the acrylic-resin substructure, and the ability to minimize disfigurement of a congenitally deformed face.

Acrylic Resins↗

A 5-year prospective multicenter follow-up report on overdentures supported by osseointegrated implants.

This report presents the results of a 5-year prospective multicenter study including nine centers worldwide. A total of 30 patients received 117 Brånemark implants in the maxillae, and 103 patients received 393 implants in the mandibles. According to the protocol, all integrated maxillary implants were to be loaded; however, only two of four mandibular implants were planned for support of the overdentures, leaving the remaining implants covered by mucosa as backup for possible implant failures. Thirty-five patients (26.3%) who were provided with 127 implants (24.9%) were withdrawn from the study. Six patients treated in the maxilla lost all their implants and resumed wearing complete dentures. The cumulative success rates for implants and for overdentures supported by two implants in the edentulous mandible were 94.5% and 100%, respectively. The corresponding cumulative success rates for implants and for overdentures supported by an optimal number of implants in the maxilla were 72.4% and 77.9%, respectively. Significantly better jawbone characteristics at the time of implant surgery were considered to contribute to the better cumulative success rates in the mandibles. Mean marginal bone loss was 0.8 mm (SD 0.8) and 0.5 mm (SD 0.8) for loaded implants during a 5-year period of time in the maxillae and mandibles, respectively. Measurements of the clinical height of the abutment cylinders indicated a mean recession (0.2 mm) of peri-implant mucosa during the follow-up period in the mandibles. Conversely, hyperplasia was observed in the maxillae.

Adult↗

Locating angulated abutments: a technical note.

A simple laboratory-made acrylic resin guide offers rapid location of angulated abutments after the healing abutments are removed. An impression recording the relation of the implants to the dental arch enables the choice of abutments to be made in the laboratory. The precise position and angulation of each abutment can be transferred to the mouth.

Acrylic Resins↗

The challenge of replacing complete dentures: Part 1.

Complete dentures need to be replaced at suitable intervals-either because of changes in the denture-bearing tissues, usually due to alveolar resorption, or because of general deterioration of the existing dentures. The purpose of this and the following article is to consider the challenges that arise in replacing complete dentures. The rationale for using techniques in which features of existing dentures can be employed in the construction of replacement complete dentures will be discussed, together with methods suitable for clinical practice. In the first part diagnosis and treatment planning will be considered and a variety of copying techniques reviewed. The limitations of these techniques will be discussed and alternative treatment strategies will be considered.

Dental Restoration Wear↗

Prosthodontic treatment, patient response, and the need for maintenance of complete implant-supported overdentures: an appraisal of 5 years of prospective study.

The prosthodontic methods and outcomes of treating 127 patients in nine centres over a period of 5 years is described. The benefits perceived by patients and the changes induced in the denture-bearing tissues and temporomandibular joints are reported. To sustain effective treatment outcomes, the levels of maintenance needed by the overdentures are contrasted for restoration of the edentulous mandibles and maxillae.

Alveolar Bone Loss↗

Replacement of successful fixed implant prostheses using duplication techniques.

Replication of desirable design features of an existing implant prosthesis is often appropriate in the construction of a replacement that produces the same spatial relationship to the supporting dental implants. An adaptation of a laboratory copy technique used in conventional complete denture prosthodontics is described. A silicone putty mold that enables the creation of the corresponding fit surface, polished surface, and arch form is used for making a transitional or a definitive complete or partial fixed implant prosthesis. Variations using a basic replication technique are appropriate in clinical practice for refabricating a prosthesis of a preferred design. The procedure is suitable for both acrylic resin-metal or metal ceramic restorations.

Dental Impression Technique↗

Effect of prefabricated bar design with implant-stabilized prostheses on ridge resorption: a clinical report.

This investigation was concerned with the resorption of the posterior mandibular residual ridge in patients wearing mandibular overdentures supported by either parallel-sided bars (rigid joint) or oval straight bars (resilient joint) on two activated implants. Rotational tomographs were taken shortly after implant placement and up to 8 years later. Using proportional measurement, the area of residual ridge was measured in bilateral posterior areas. Patients rehabilitated with implant-stabilized mandibular overdentures demonstrated posterior mandibular residual ridge resorption at low rates, which were not significantly influenced by the design of the prefabricated bar.

Adult↗