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PubMed2002

Simplified clinical procedure for fitting and removing inlays/onlays prior to cementation.

This article describes a procedure in which polytetrafluoroethylene (PTFE) tape is used as a liner for fitting intracoronally retained, indirect restorations. The minimal thickness of the tape allows complete seating and confirmation of marginal fit of restorations during try-in, yet the tape is tough enough to permit trouble-free removal of the restoration afterward. Protection against inadvertent loss of the restoration can be gained if a knot is placed close to the occlusal surface of the restoration prior to its removal.

Cementation↗
PubMed2003

Use of magnification in dental technology.

UNLABELLED: Binocular stereoscopic microscopes have been used in dental technology for decades to improve visual acuity during the fabrication process. Technicians endeavor to produce a restoration that has marginal discrepancies of < 50 microm and to polish the surface of the restorative material so that there is minimal bacterial accumulation. There are six key areas in which the use of magnification is critical to fabricating high-quality restorations: inspection of the impression; trimming and marking of the margin on the die; waxing of the margin; fitting of the initial casting, pressing, or milled unit; final fitting of the restoration; and polishing of the restoration. This article explains some of the specific areas in which dental technicians rely on magnification to increase the probability of a long-term biologically acceptable restoration. CLINICAL SIGNIFICANCE: Precision in the dental laboratory during fabrication of indirect restorations is crucial to long-term clinical success. An intimate but passive fit to the restoration ensures complete seating at the time of cementation with excellent marginal integrity and subsequent minimal occlusal adjustments. A restorative surface that is smooth and well polished in the gingival third results in minimal bacterial accumulation and a healthy periodontium.

Dental Casting Technique↗
PubMed2000

The orthotic management of the congenitally short lower limb--a new appliance.

AIM: To describe an appliance used for equalisation of severe congenital lower limb length discrepancy for patients who refuse to undergo any operative correction but wish to walk and look better. METHOD: The appliance which is a combination of an ischial bearing brace and a below knee prosthesis was fitted to four patients, aged between 12 and 31 years, with congenital shortening of the lower limb ranging between 17 to 27 centimetres. The diagnosis was proximal femoral focal deficiency in 2 patients, hypoplastic femur in 1 and tibial hemimelia in the fourth patient. The appliance could accommodate existing deformities of the knee, ankle and foot without any operative correction as well as equalise the lower limb length. It is modular in construction and could be easily assembled from off-the-shelf components. RESULT: The appliance improves the gait as well as the appearance, could be fitted to the patient without the prior need of operative correction and could be well disguised under any loose fitting garment. Four patients with severe congenital shortening of the leg have used it for over three years and are pleased with it. It requires little maintenance. CONCLUSION: The appliance is useful for patients with severe congenital shortening of the lower limb who refuse to undergo operative correction.

Adolescent↗
PubMed2000

Fitting of electronic elbow on an elbow disarticulated patient by means of a new surgical technique.

Rehabilitation of trans-humeral amputees represents a challenge. One of the difficulties to overcome is prosthetic suspension. In the case of elbow disarticulation the presence of humeral condyles permits better suspension, but there is no room for elbow joints, particularly electronic ones, and the only available mechanisms are provided by external hinges. The purpose of this report is to present a case of a primarily elbow disarticulated patient, with indication for surgical revision due to bad skin coverage, neuroma and the wish to improve prosthetic fitting. The surgical plan outlined was to produce a shortening of the humerus, by means of an osteotomy just above the humeral condyles, preserving them for prosthetic suspension. This bone reduction was carried out with complementary shaping of bone segments with an indentation to enhance fixation. The operation was completed with neuroma resection, myodesis and removal of the skin grafted area. Preservation of the humeral condyles actually produced effective suspension. For final fitting a Utah Arm II was used, with wrist rotator, and interchangeable hand and Greifer for terminal devices. Good initial results and at nine months follow-up suggest this procedure should be considered in other elective situations.

Accidents, Traffic↗
PubMed2005

Contact lenses and special back surface design after penetrating keratoplasty to improve contact lens fit and visual outcome.

AIMS: To describe the fitting of patients with high or irregular astigmatism following penetrating keratoplasty with contact lenses and to answer the question whether or not contact lenses with special back surface design can improve visual acuity in complex cases after penetrating keratoplasty. METHODS: 28 eyes were included. They were fitted with contact lenses with a special back surface that was designed for optical rehabilitation after penetrating keratoplasty. Four different types of these lenses (tricurve, keratoconus, reverse, oblong) were used selectively depending on abnormal eccentricity determined by videokeratoscope. The patients were followed up for an average period of 15.5 months. Lens tolerance and corrected visual acuity were evaluated and compared with that corrected with spectacles. RESULTS: The visual acuity was significantly improved in nearly all eyes with an average increase of 3.6 lines (maximal nine lines) accompanied by good contact lens tolerance and satisfactory contact lens fit. No noticeable complications were observed. CONCLUSION: Contact lenses with special back surface design can improve visual results and lens tolerance, and minimise problems in contact lens fitting. This is in favour of contact lenses as an alternative to surgical procedures for correction of high or irregular astigmatism after penetrating keratoplasty. This procedure is recommended especially in cases of patients who decline further operative interventions.

Adult↗
PubMed1999

Variables affecting the use of prescriptive formulae to fit modern nonlinear hearing aids.

It is routine for audiologists to fit nonlinear hearing aids by using one of several current prescriptive formulae. While such an approach might result in acceptable fittings for single-channel analog compression hearing aids, its direct application to fitting current multichannel compression hearing aids may result in less than an optimal fit. In this paper, the effects of filter bandwidth, number of channels, detector type, compression threshold, attack and release times, and distortion on the final output of a nonlinear compression hearing aid are discussed. The subjective results of such effects and its implications on our clinical practice will be explored as well.

Acoustic Stimulation↗
PubMedDate not supplied

A simplified technique for construction of an interim obturator for a bilateral total maxillectomy defect.

PURPOSE: This report describes a simplified method for construction of an interim obturator for a huge maxillary defect. MATERIALS AND METHODS: A medical grade-silicone obturator was fabricated indirectly on a duplicate cast of the surgical defect for a patient with a bilateral total maxillectomy. This silicone obturator was attached to an acrylic plate by means of mushroom-like extension tags projecting from the fitting surface of the acrylic palatal plate. RESULTS: The obturator was well retained in the patient's mouth and markedly improved his ability to speak and swallow. CONCLUSION: This technique proved to be a simple, quick, and cost-effective method for construction of obturators for huge maxillary defects.

Acrylic Resins↗
PubMed1998

Squamous cell tumors and ocular prostheses.

Conjunctival squamous cell carcinoma is an infrequent tumor. It has been reported to occur in association with actinic damage and chronic irritation. To the authors' knowledge, however, this tumor has not been reported secondary to poorly fitting ocular prostheses. Two patients were studied in whom conjunctival squamous cell carcinoma had developed. In both instances, the patient had been enucleated and fitted with an ocular prosthesis more than 40 years before tumor development. Histopathologic evaluation of each tumor revealed its squamous cell origin. In one of the patients, the tumor was found to be metastatic to the ipsilateral parotid gland, an uncommon finding. The authors attempted to identify risk factors that may have contributed to the development of these tumors. Aside from the poor fit of the prostheses, neither patient had significant risk factors for the development of conjunctival squamous cell carcinoma. It is concluded that a new, sanguineous conjunctival discharge or focal eyelid swelling after years of prosthetic wear may not be due to mechanical irritation alone. The onset of these symptoms, especially years after the initial fitting of an ocular prosthesis, should prompt a thorough investigation of its cause.

Aged↗
PubMed2000

Evaluation of a new system of lens parameter selection and comparison of traditional vs one-step lens care systems for aspheric high-Dk RGP contact lenses.

PURPOSE: We investigated the value of newly developed systems for parameter selection on the performance of high Dk rigid gas permeable (RGP) contact lenses with a spheric-aspheric design made of Boston Equa material in normal daily wear conditions. A comparison was also made between the safety and efficacy of a traditional care system vs a one-step chemical care system during the follow-up period of 1 year. METHODS: A total of 66 patients were randomly assigned to traditional and newly developed systems for computing the back optical zone radius (BOZR) and the total diameter (TD) of the lenses. Evaluation parameters incorporated assessment of fit, visual acuity, wearing time, comfort, and lens condition. RESULTS: The traditional method of computing the BOZR, using a method based on flat-K, predicted the BOZR successfully in 83% of the cases. Corneal topometry reached a lower, but not significantly different (P > 0.01) value of 75% correct prediction of BOZR. Analysis of the differences in eccentricity (E) values between quadrants per eye was a significant (P < 0.001) factor in fault predictions in the topometric system. A newly developed guide forTD selection performed, with 90% correct predictions, significantly (P < 0.01) better than a traditional method (72%) based on corneal diameter on supraversion. No significant differences (P > 0.05) were found in the capabilities of care systems (a traditional care system using a surfactant cleaner vs a one-step solution) to keep the lenses in proper condition and without deformation, over the 1 year follow-up period. The final success rate was 85%. CONCLUSIONS: Although high Dk RGP contact lenses can be fit and used with a 85% success rate using advanced systems for determining the BOZR and TD, it remains necessary to evaluate the fit before dispensing high Dk RGP lenses in 15% of the cases. The one-step solution used in this study was a good starting point for lens care. If needed, surfactant cleaning in the traditional care system can be done without the risk of lens deformation.

Adolescent↗
PubMedDate not supplied

Outcomes of lengthening short lower-extremity amputation stumps with planar fixators.

Patients with short lower-extremity amputation stumps exhibit poor prosthetic fit and inefficient gait. Often they are fit at the next-higher prosthetic level, increasing energy consumption. This study aimed to characterize the risk/benefit ratio of stump lengthening with planar external fixators. All patients lengthened for functionally short amputation stumps were reviewed. Outcome measures included changes in prosthetic use, soft tissue problems, qualitative gait analysis, and surgical complications. Patients averaged 15.1 years of age at surgery, with 4.1 years of follow-up. The average lengthening index was 9.2 mm/mo. Femoral lengthenings obtained more length (8.7 vs. 6.9 cm). After treatment, prosthetic skin-related complications decreased and qualitative gait parameters improved. Most (85%) wore a standard prosthesis for their amputation level after surgery, whereas none could before. There were 1.4 complications per patient, all successfully surgically treated. Lengthening is time-consuming and associated with frequent complications but results in improved gait and energy consumption.

Adolescent↗
PubMed1997

Fit discrimination of implant-supported fixed partial dentures fabricated from implant level impressions made at stage I surgery.

STATEMENT OF PROBLEM: The implant level impression can shorten the overall time frame of implant treatment. PURPOSE OF STUDY: The purpose of this study was to analyze the accuracy of fixed partial dentures constructed from impressions taken at implant installation surgery in partially edentulous dogs. The study compared the fit of welded titanium fixed partial dentures with that of cast gold alloy fixed partial dentures. MATERIAL AND METHODS: Three implants were placed on each side of the mandible in six adult greyhound dogs during stage I surgery. Impressions were taken of the implant positional relationships and two types of fixed partial dentures were fabricated for each side of the mandible. Stage II surgery was performed after 3 months. RESULTS: Both types of fixed partial dentures compared favorably with the fit of implant-supported fixed partial dentures in the edentulous jaw or traditional cast fixed partial denture frameworks. CONCLUSIONS: Impressions taken at implant installation surgery provide a valid transfer of information for the laboratory fabrication of the final restoration when the implants are placed to fulfill the requirements of primary stability.

Animals↗
PubMed2004

[Examination to possibilities of a physiological fitting of cochlear implants].

BACKGROUND: Cochlear implants (CI) convert acoustic events into electrical pulses. The auditory nerve picks these tiny electrical pulses up and sends them to the brain. The dynamics of the audible sound is compressed considerably. The limits for stimulation are determined with the patient. A map law determines which sound pressure level is assigned to which stimulation level. A sufficient speech understanding requests an allocation of high stimulation levels for weak sound signals. The higher the sound level, the lower the increase. Unfortunately, with such kind of map law unwanted background noise is also presented as well audible stimulation. These stimuli are often annoying to CI users in everyday situations. PATIENTS AND METHOD: The possibility to give an s-shaped course to these map laws was examined in 9 patients. After the fitting procedure their speech understanding were tested. The results were compared with the results of former tests. RESULTS: 8 patients reported definite improvement of their hearing situation. Such map laws seem, therefore, suitable to optimise speech processor programming.

Adult↗
PubMed1995

Clinical performance of a spline-based apical vaulting keratoconus corneal contact lens design.

We refit 68 eyes with keratoconus and recurring contact lens induced apical corneal erosions with rigid corneal contact lenses having computer-generated spline curves. This junctionless design incorporates two independently configurable fitting zones on the back surface of the lenses that enable them to fit most keratoconus eyes with an apical vault rather than the traditional two or three point touch. Apical staining was eliminated in 49 eyes (72%), significantly reduced in 13 eyes (19%), and remained unchanged in six eyes (9%). Corneal abrasion related symptoms of contact lens wear intolerance resolved in 41 of 43 eyes.

Computer-Aided Design↗
PubMed2001

A new technique for rigid gas permeable contact lens fitting following penetrating keratoplasty.

PURPOSE: To evaluate a new, rigid gas permeable contact lens fitting technique following penetrating keratoplasty. METHODS: For the correction of postoperative anisometropia or astigmatism, a rigid gas permeable, tetra-curve contact lens with an overall diameter of 12.0 mm and a back optic zone diameter of 8.5 mm was fitted in 36 eyes of 33 patients, 7 months after penetrating keratoplasty. The contact lens back optic zone radius was selected using the videokeratography values over the elevated edges of the transplant wound (with the sutures in place). Graft clarity, visual outcome, and corneal topography were evaluated up to 3 years after surgery at intervals of 6 months. RESULTS: Throughout the follow-up period (range 6-36, mean 19.3+/-sd 11.8 months), all grafts remained clear. Mean contact lens daily wearing time averaged 13.6 (+/- sd 4.7) hours. Mean best-corrected visual acuity improved from +0.36 (+/- sd 0.18) LogMAR with spectacles to +0.11 (+/- sd 0.11) LogMAR with contact lenses (p < 0.0001). One patient was excluded from the study due to a lack of motivation and one had an adverse reaction to the stitches. CONCLUSIONS: To improve the visual performance following penetrating keratoplasty, the described fitting technique, guided by videokeratography, eased selection of the back optic zone radius of the initial trial lens. The large diameter contact lenses with a tetra-curve design were well tolerated in all patients for more than 13 hours daily.

Adult↗
PubMed2003

[Are titanium implants superior to gold implants in the tympanic cavity?].

BACKGROUND: Gold implants in reconstructive surgery of the middle ear have proved to work sufficiently: That applies to tympanic cavity conditions without signs of chronic inflammation as also to the bacterially infected middle ear. For some years titanium implants are also in the use and established as well. The biocompatibility of titanium, the clinical and the audiological results are satisfactory. When using gold-prostheses in stapes surgery however, the still unsolved problem of occasional deafness has to be considered. PATIENTS: The clinical and functional results of middle ear surgery were examined retrospectively. There was no preselection of patients. 53 patients underwent middle ear surgery with titanium prostheses, 42 patients with gold prostheses. RESULTS: Due to their material properties and due to their delicate shape titanium prostheses (PORP, TORP) can be inserted into the tympanic cavity more simply and with better fit. The audiological results of gold and titanium prostheses are comparable. The extruding rate of the gold prostheses is substantial, whereas the extruding rate of titanium is negligible. CONCLUSION: The functional results of both materials are comparable. Due to the high extruding rates of gold prostheses titanium is clearly superior.

Auditory Threshold↗
PubMed2006

Temporal bone results and hearing preservation with a new straight electrode.

Due to improved technology, cochlear implant (CI) candidacy has been widened towards patients with usable residual hearing in the low frequency range. These patients might benefit from additional acoustic amplification provided that residual hearing can be preserved with cochlear implantation. To provide a high probability of hearing preservation, a new electrode array was designed and developed at the Medizinische Hochschule Hannover. This 'Hybrid-L' electrode array has 22 electrodes spread over 15 mm with an overall insertion depth of 16 mm. The straight electrode with modiolus facing contacts is designed for a round window insertion. It shall provide the full range of the currently most advanced Nucleus CI system. A temporal bone study demonstrated the favorable insertion characteristics and minimized trauma to intracochlear structures. Compared to standard CI electrodes especially no basilar membrane perforation could be found. So far, 4 patients have been implanted and residual hearing could be preserved. One patient was fitted and showed a marked additional benefit from the electroacoustic stimulation compared to either acoustic or electrical stimulation alone. These results are very encouraging towards a concept of reliable hearing preservation with cochlear implantation.

Acoustic Stimulation↗
PubMed2000

Peripheral corneal contour measured by topography influences soft toric contact lens fitting success.

PURPOSE: Empirical fitting success is important to expanding the soft toric contact lens market. Previous study has lead to the hypothesis that lens flexure may alter expected fitting relationships and back vertex power (BVP) in situ. In this study, baseline topographic features as potential variables in predicting soft toric fitting success were analyzed. METHODS: One-hundred forty-nine eyes were empirically fit with back surface toric soft lenses after placido-based videokeratography was performed. Measurements recorded from baseline instantaneous maps included: flat simulated keratometry (Sim-K) value (in diopters) and axis, steep Sim-K value (in diopters) and axis, eccentricity of the flat meridian, and the form of corneal astigmatism. Astigmatism was classified as types I-V based upon differences between central and peripheral corneal toricity. RESULTS: Ninety-three of 149 (62.4%) eyes were successfully fit empirically with the first trial lens. One-hundred thirty-five of 149 (90.6%) eyes were ultimately successful after unsuccessful trial lenses were adjusted and reordered. There were no differences between the empirically fit success and failure groups in instrument reported eccentricity, Sim-K values, or Sim-K axes (P>0.05). Of 115 eyes classified for form of corneal astigmatism, 76 (66%) were classified with high or irregular peripheral astigmatism (types IV and V). There was a significant association between fitting success and the form of corneal toricity (P=0.0327). Thirty-nine of 115 (34%) eyes were classified as corneal types I-III (spherical or minimally toric corneal periphery) and were associated with empirical fitting success (P=0.0092). CONCLUSION: Empirical soft toric fitting success can be anticipated in spherical corneas, central astigmatism, or corneas with peripheral toricity which matches the central toricity. However, high and irregular peripheral corneal toricity occurs in the majority of astigmatic patients. Corneal topography is a valuable tool to assess peripheral astigmatism which may be one factor influencing unexpected lens performance.

Astigmatism↗
PubMed2001

Practical experience with a high Dk lotrafilcon A fluorosilicone hydrogel extended wear contact lens in Spain.

PURPOSE: Several research studies on high Dk soft contact lens materials have been published, but little has been reported from practical clinical experience with these new materials. This study reports in-practice clinical experience with the lotrafilcon A fluorosilicone hydrogel material from a 6-month study in Spain. METHODS: Eighty-five patients were dispensed lotrafilcon A lenses (Focuse NIGHT & DAY [CIBA Vision Corporation]) for monthly replacement by 13 investigators from eight practices. The recommended wear schedule was daily wear for the first week and then up to 6-night extended wear through the first month and up to 30-night extended wear through 6 months. Follow-up visits were at 1 week, 1 month, 3 months, and 6 months. Clinical and patient subjective data were collected at each visit. RESULTS: Among patients who continued in the study at each visit, Snellen visual acuity (VA) of 20/25 or better was achieved by at least 96% of all eyes at all visits; lens surfaces assessments for front surface deposits, front surface wetting, and back surface debris averaged less than grade 1 (0-4 scale) for all lenses at all visits; biomicroscopy grades averaged well below grade 1 (0-4 scale) for all eyes at all visits; acceptable or optimal fit was assessed for 97% or more of all lenses at all visits. These patients rated the average overall comfort, vision, and handling above 9 (0-10 scale) at 6 months and 98% reported satisfaction with the lenses at 6 months. Eighty-two percent of patients dispensed completed the study. Seven patients were discontinued because of fit, and seven were discontinued because of positive biomicroscopy signs. CONCLUSIONS: The lotrafilcon A lens performed well clinically and it was accepted well by patients, with most practitioners recommending and most patients wearing it for up to 30 nights extended wear. Practitioners should be attentive to fit and discomfort complaints at dispensing and follow-up and may want to recommend lubricating or rewetting drops for those patients with dryness symptoms.

Adolescent↗