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PubMedDate not supplied

In vitro study on passive fit in implant-supported 5-unit fixed partial dentures.

PURPOSE: Fabrication and retention methods have an influence on the passivity of superstructure fit. The objective of the study was to quantify the strain development of various cemented and screw-retained fixed partial dentures (FPDs). MATERIALS AND METHODS: Forty samples of 4 different types of FPDs (10 of each type) were investigated. Each sample had 3 ITI implant abutments and 2 pontics. The 3 implants were anchored in a straight-line configuration in a measurement model simulating a real-life patient situation. Strain gauges were mounted close to the implants and on the pontics. The developing strains were recorded during cement setting and screw fixation. For statistical analysis, multivariate 2-sample tests were performed, with the level of significance set at P = .1. RESULTS: All FPDs investigated revealed a considerable amount of strain, with no significant difference between cement and screw retention. Furthermore, no significant difference was found between the conventional fabrication modes for screw-retained FPDs. The lowest strains were found in prostheses that were intraorally bonded onto gold cylinders. DISCUSSION: Because bonding of the superstructure in the oral cavity may compensate for impression and laboratory variables, restorations with the best possible passive fit can result from this retention technique. Before this technique can be recommended, the long-term stability of the adhesive layer should be investigated. CONCLUSIONS: As an absolute passive fit of superstructures is not possible using conventional clinical and laboratory procedures, and as clinical fit-evaluation methods often do not detect "hidden" inaccuracies, the more sensitive strain-gauge technique should be utilized for an objective accuracy test. Reference strain values from implant-supported prostheses that have served without complications could help define a "biologically acceptable fit.

Aged↗
PubMed2003

Psoriasis and the effect of prosthetic fitting.

This contribution presents the case histories of two patients who underwent limb amputation. One patient suffered from psoriasis prior to the surgery and the second developed psoriatic lesions post surgery. Both patients were provided with a prosthesis and despite the multiple cutaneous complications of the psoriasis both patients ambulate. It was expected that Koebner's phenomenon would create hardships but to date this has not happened.

Adult↗
PubMed1999

The influence of friction and interference on the seating of a hemispherical press-fit cup: a finite element investigation.

The formation of gaps in the polar region of acetabular cups is seen as a drawback of press-fit fixation of non-cemented acetabular cups. Recent findings indicate a link between long-term polar gaps and the gaps present directly after implantation. In this study the process of press-fitting is simulated with a linear-elastic two-dimensional axisymmetric finite-element model. The aim of this paper is to investigate the possible importance of friction and interference on the formation of these gaps. A range of cup-bone friction coefficients (mu = 0.1-0.5) is assigned to the cup-bone interface in order to represent the unknown amount of friction occurring during press-fitting. The cup is modeled with a radius of 27 mm, whereas the radius of the cavity is varied between 26.50 and 26.75 mm, thus, creating 0.50 and 0.25 mm radial interference fits. The difference in cavity radius represents the discrepancy between the radius of the last-reamer-used and radius of the cavity it creates. The subchondral plate is considered as being completely removed during reaming. The effects of impact blows via the surgeon's mallet during surgery are modeled as a series of four load pulses, in which peak force is gradually increased from 0.5 to 4.0 kN. The effects of load removal as well as those of load application are investigated. On load application, the cup penetrates into the cavity, and on load removal, the cup rebounds. Depending on the friction, interference and load applied, the position of the cup after the load pulse is somewhere between its position at peak force and its position at the beginning of the pulse. Although the simplifications and conditions involved in the creation of the model necessitate caution when interpreting the results for all clinical cases, it is found that the seating of hemispherical cups in trabecular bone could be more satisfactory for intermediate values of friction (mu = 0.2-0.3) and smaller interference fits (0.25 mm).

Acetabulum↗
PubMed1994

The 'Allan Johnson' voice prosthesis. A modification of the Bivona voice prosthesis for immediate post-fitting aphonia after secondary tracheo-oesophageal puncture.

The combination of a narrow oesophageal lumen and a hypertonic pharyngo-oesophageal (P-E) segment following laryngectomy and secondary tracheo-oesophageal puncture (TEP) can cause obstruction of a voice prosthesis and consequently prevent phonation. The 'Allan Johnson' modification of the Bivona voice prosthesis incorporates a stainless steel slide and has been successfully used to remedy such a circumstance.

Aphonia↗
PubMed2001

Comparison of two digital hearing instrument fitting strategies.

Two different hearing instrument fitting strategies were compared in the laboratory and in a field test with regard to the benefit for hearing aid users and their satisfaction with the fitting. DSL [input/output (i/o)] fittings based on hearing threshold and uncomfortable levels for the subject were evaluated vs a prescriptive fitting method based on unaided loudness scaling. Twenty-one subjects were fitted diotically with both fitting strategies implemented in a digital hearing instrument (Siemens Prisma). The patients tested both fitting strategies sequentially in a 4 + 4-week field trial using a crossover study design. Speech recognition threshold measurements, sound quality ratings and paired comparisons of sound quality were performed for all conditions (unaided, DSL[i/o] fitting and loudness-based fitting). In addition, subjective benefit and preference were assessed with questionnaires. Speech audiometry did not reveal significant differences between the two fittings. DSL[i/o] fittings showed superior results in most sound quality tests and in the self-assessment of communication abilities while the loudness-based approach was slightly preferred in noisy environments. The results seemed to be influenced by the higher gain predicted by DSL[i/o]. This study provides no evidence that effort spent on loudness scaling leads to improved fitting results.

Audiometry, Speech↗
PubMed1997

Clinical evaluation of a topographically based contact lens fitting software.

BACKGROUND: Second generation corneal topography-based contact lens software programs attempt to fit the cornea based on topographical information rather than simulated keratometry and nomogram-based fits. The EyeSys System 2000 Pro-Fit software (Version 3.1) was clinically evaluated for efficiency in fitting rigid gas permeable (RGP) lenses on 22 normal subjects. METHODS: Balanced manifest refractions, slitlamp examinations, keratometry, computerized topographic analysis and lens fitting, and manual diagnostic RGP fitting were performed on all patients. The topographically fit eyes were compared to corresponding eyes which were manually fit with diagnostic trial lenses. Lens parameters for the topographically fit eye were chosen after an optimal fluorescein pattern was achieved by either accepting the initially recommended Pro-Fit lens or a modification. Final lens parameters were based on clinical performance. Lenses were reordered when there was a need for base curve changes of 0.1 mm or more, power alterations of +/- 0.50 D or more, or for any alteration in diameter, optic zone, or edge lift. RESULTS: Both manual and topographically fit groups achieved 17/22 (77%) eyes successfully fit without any subsequent lens modifications. Time records for the manually fit group averaged 16.5 min, whereas the topographically fit group averaged 8.0 min. CONCLUSIONS: This study reports a 51.4% reduction in chair time when using a topographically based contact lens software program while achieving the same clinical results as in traditional diagnostic RGP fitting, suggesting increased efficiency in fitting RGPs to normal eyes.

Astigmatism↗
PubMed1996

Corrected master cast procedure for intraoral luted implant frameworks.

Large cast frameworks rarely fit multiple implant abutments passively without time-consuming labor-intensive adjustment procedures. Intraoral luting of components has been suggested to achieve a passive fit and eliminate most adjustment procedures. When the intraoral luted framework is returned to the master cast, the implant analogs may not be properly aligned to framework abutments. To complete the restoration, master cast modification or replacement may be required. The procedure described in this article produces a corrected master cast that fits the final framework and preserves the tissue topography of the original master cast.

Dental Polishing↗
PubMed1999

Measurements of loudness growth in 1/2-octave bands for children and adults with normal hearing.

The loudness growth in 1/2-octave bands (LGOB) procedure has been shown previously to provide valid estimates of loudness growth for adults with normal hearing and those with hearing loss (Allen, Hall, & Jeng, 1990), and it has been widely incorporated into fitting strategies for adult hearing aid users by a hearing aid manufacturer. Here, we applied a simple modification of LGOB to children and adults with normal hearing and then compared the loudness growth functions (as obtained from end-point data) between the two age groups. In addition, reliability data obtained within a single session and between test sessions were compared between the two groups. Large differences were observed in the means between the two groups for the lower boundary values, the upper boundary values, and the range between boundaries both within and across all frequencies. The data obtained from children also had greater variance than the adult data. In addition, there was more variability in the data across test sessions for children. Many test-retest differences for children exceeded 10 dB. Adult test-retest differences were generally less than 10 dB. Although the LGOB with the modifications used in this study may be used to measure loudness growth in children, its poor reliability with this age group may limit its clinical use for children with hearing loss. Additional work is needed to explore whether loudness growth measures can be adapted successfully to children and whether these measures contribute worthwhile information for fitting hearing aids to children.

Adult↗
PubMed1996

MRI as an aid to the fitting of tracheo-oesophageal Blom-Singer valves post-laryngectomy.

The Blom-Singer valve is a device for facilitating speech in patients who have undergone total laryngectomy. The valve is inserted into a surgically created tracheo-oesophageal fistula. Fitting the valve and determining the correct length and direction of the fistula, although usually straightforward, can be difficult. We describe two patients in whom MR imaging of the fistula tract has aided valve fitting.

Adult↗
PubMed2000

Efficiency and accuracy of two computerized topography software systems for fitting rigid gas permeable contact lenses.

PURPOSE: The world of computerized videokeratoscopy is continually evolving. Computerized videokeratoscope contact lens programs boast the capability to accurately design final rigid gas permeable (RGP) lens parameters and simulate contact lens fluorescein patterns. We evaluated the EyeSys System 2000 Pro-Fit software (v. 4.0) and Humphrey Atlas MasterVue Contact Lens Module (v. A6) for efficiency and accuracy in fitting RGP contact lenses on normal subjects. METHODS: Balanced manifest refractions, slit lamp examinations, and computerized topographical analysis with RGP module lens fitting were performed and compared for all eyes. Lens parameters were chosen after an optimal simulated fluorescein pattern was achieved by either accepting the initially recommended default lens or a modification. Final lens parameters were based on clinical performance. RESULTS: With the Humphrey Atlas software, which uses a default topographic tear clearance fitting protocol set by the manufacturer, 24/50 (48%) eyes required modifications to the default fitting parameters based on the simulated fluorescein patterns. Nine of 50 eyes (18%) required further modifications once the RGP lens was dispensed. The EyeSys Pro-Fit software, which allows a custom tear clearance fitting protocol set by the user as default, required modifications to 20/35 eyes (57.1%) from default fittings provided by the system. Six of 35 eyes (17.1%) required subsequent modifications once the RGP lens was dispensed. Comparison of the EyeSys to Humphrey modules revealed no significant difference in efficiency (P=0.51), defined as any changes required to the default parameters; however, the user made more modifications to the EyeSys module from the default setting. There was no significant difference in final success rates between EyeSys (82.9%) and Humphrey (82%) systems (P=1.00). CONCLUSION: Although both topography guided contact lens modules offered accuracy in RGP fitting, a user programmed default (EyeSys) protocol did not improve efficiency in RGP lens parameter selection compared to a manufacturer programmed default module (Humphrey). The need for a knowledgeable contact lens fitter remains to guide the systems in achieving the optimal fit.

Contact Lenses↗
PubMedDate not supplied

Clinical application of the satisfaction with amplification in daily life scale in private practice I: statistical, content, and factorial validity.

Statistical, content, and factorial validity of the Satisfaction with Amplification in Daily Life (SADL) scale was assessed. SADL subscales closely correspond to four satisfaction domains. Subjective benefit is a key component of satisfaction, but other nonauditory factors contribute to wearer satisfaction, notably telephone use and appearance. Results confirm the SADLs psychometric properties and verify its use to validate hearing aid fitting satisfaction in private practice settings for a general patient population at 1-year postfitting. Interim SADL norms may be refined as more SADL data are obtained for different patient populations, hearing aid types, and fitting environments.

Aged↗
PubMed1996

Prosthetic rehabilitation after craniofacial surgery.

We report our experience during the last 6 years with 20 patients fitted with prosthesis (19 patients with osseointegration of screw, 1 patient with primarily gluing method) for camouflage of congenital or acquired (trauma, tumor resection) defects of the ear, nose, or eye. Out of a total of 53 extra-oral implants fitted, 3 were lost in the orbital area due to loosening 6 months after radiation treatment. Another three implants were removed at the request of an 80-year-old patient who preferred a prosthesis retained by spectacles because of recurring infection around one of the implants. On average, 43 months (range, 7 months to 8 years) after completion of the prosthesis, 85% of the patients assessed the result as excellent, 15% as good, 0% as fair, and 0% as poor. The ENT surgeon and the prosthesis designer were slightly more critical (ENT surgeon-95% good or excellent and 5% fair, prosthesis designer-90% good or excellent, 10% fair).

Journal Article↗
PubMed2002

The outcome of oral mucosal grafts to the orbit: a three-and-a-half-year study.

A 3 1/2 year audit of the outcome of oral mucosal grafts was conducted at the occuloplastic service of Wentworth Hospital, Durban, South Africa. We studied 17 consecutive patients with ages ranging from 2 years to 83 years; young males predominated. The causative pathologies included six gunshot wounds, three retinoblastomas, two congenital abnormalities, two childhood traumas, a chemical burn, an occular pemphigoid, a stab wound and a firework injury. We treated 14 patients for a contracted socket, and performed mucosal grafts to the globe in the other three. Prostheses were successfully fitted in 12 of the patients with a contracted socket and in one patient with microphthalmia. Of the former patients, 10 had a good result and two had a fair result. Out of the 14 patients with a contracted socket, 10 required a repeat procedure. An onlay prosthesis was used instead of an inlay prosthesis in one patient because of the child's social circumstances; one patient was lost to follow-up. During the first year of the study, a thermoplastic conformer of Stent's composition was used. This was later changed to a plug of medicated paraffin gauze, which was easier to use. A permanent prosthesis was fitted 1 week postoperatively. The crucial factor for success was that there should be no delay between removing the plug and inserting the prosthesis. A single-stage reconstruction of the orbital wall and socket using costal cartilage and temporalis fascia together with an oral mucosal graft is discussed for reconstruction following gunshot wounds or retinoblastoma enucleation and radiotherapy. Oral mucosal grafts can be used successfully to reconstruct the conjunctiva on the globe and in the fornices.

Adolescent↗