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Biomedical subjects

D M Shafer

Publications and source records attributed to D M Shafer.

At least 19 recordsLinked to original sources
PubMed2006

Comparison of five different abdominal access trocar systems: analysis of insertion force, removal force, and defect size.

Trocar designs have evolved in response to concerns about complication rates and surgical ergonomics. Functional properties of trocar systems that can be objectively measured include insertion force, removal force and the size of the tissue defect. This study will evaluate these properties in 5 common trocar designs. A porcine model was used to evaluate five different trocar systems for insertion force, removal force, and functional and measured tissue defect. Insertion force was lowest for cutting trocars and highest for radially dilating trocars. Removal force was similar for all trocars. Functional and measured tissue defect size was smallest for the hybrid type and radially dilating trocars. An ideal trocar system incorporates a low insertion force, secure retention, and a minimal tissue defect. Of the systems we tested, the hybrid type trocar has similar wound characteristics to the radially dilating trocar with the benefit of reduced insertion force. Further study is required to determine if these properties translate to an actual improvement in patient outcome.

Abdomen↗
PubMed1999

Gustatory function after third molar extraction.

OBJECTIVE: The purpose of this study was to determine the severity and time course of taste changes after extraction of all 4 third molars. STUDY DESIGN: Taste function in 17 patients was measured before third molar surgery and at 1 month and 6 months after surgery. Two tests were administered: a whole-mouth, above-threshold test in which subjects sipped, expectorated, and then rated the intensities and identified the taste qualities of various solutions, and a localized test in which subjects rated and identified solutions painted with cotton swabs on different oral sites. RESULTS: Intensity ratings for solutions in the whole-mouth test were reduced by approximately 14% for NaCl, citric acid, and quinine hydrochloride at 1 month after surgery and had not recovered by 6 months after surgery for citric acid (P<.02). The taste quality of NaCl was identified correctly less frequently after third molar extraction. Perceived taste intensity on discrete areas of the tongue was significantly reduced after surgery (P<.05). Patients with the most severely impacted molars gave the lowest taste intensity ratings to whole-mouth test solutions at 6 months after surgery (P<.02). In contrast, taste function in a group of subjects who received only local dental anesthesia was not affected. CONCLUSIONS: Gustatory deficits occur after third molar extraction, persist for as long as 6 months after surgery, and appear to be associated with depth of impaction.

Adolescent↗
PubMed1998

Incremental bolus versus a continuous infusion of propofol for deep sedation/general anesthesia during dentoalveolar surgery.

PURPOSE: This article compared the use of the traditional incremental bolus technique with the continuous infusion technique for the administration of propofol for deep sedation/general anesthesia. PATIENTS AND METHODS: Patients were sedated with midazolam and fentanyl and then had maintenance of an anesthetic state achieved with propofol administered by either of the two techniques. Data were collected to evaluate the overall surgical/anesthetic procedure, movement of the patient, and his or her hemodynamic status. RESULTS: Both groups received a mean maintenance dose of propofol exceeding 6 mg/kg/hr. However, the patients in the continuous infusion group received a statistically greater maintenance dose (continuous infusion + supplemental vs incremental bolus). All patients were maintained in a deep sedation/general anesthetic state. Respiratory and blood pressure values were comparable in both groups. However, the continuous infusion group showed improved hemodynamic stability manifested as fewer fluctuations in heart rate. Visual analog scale (VAS) questionnaires completed by the surgeon and surgical assistant reported less patient movement and improved surgical/anesthetic conditions with the continuous infusion technique. Recovery of the two groups was comparable. CONCLUSION: This study, although finding advantages in the continuous infusion technique, showed satisfactory conditions associated with both techniques.

Alveolar Process↗
PubMed1996

Surgical-orthodontic correction of adult facial deformities.

The use of combined surgical-orthodontic therapy for the correction of skeletal anomalies has moved from the obscure to the routine over the last 25 years. Its use has been extended to treat not only developmental problems in children and adolescents, but also traumatic and temporomandibular joint-related deformities in adults. Its use can be integrated into a comprehensive treatment plan, including prosthodontics, periodontics, and implant dentistry. The advent of rigid internal fixation has made it particularly more appealing for the treatment of adult patients, allowing the patients to return to normal daily activities more rapidly.

Adult↗
PubMed1995

The effect of electrical perturbation on osseointegration of titanium dental implants: a preliminary study.

PURPOSE: Successful osseointegration of titanium dental implants is decreased in areas of poor bone volume and density. Low amperage direct current (LADC) has been shown to perturb bone cells, which in turn promotes bone growth. The purpose of this experiment was to evaluate the effect of LADC on the osseointegration of endosseous titanium dental implants. MATERIALS AND METHODS: Two implant sites were prepared in the body of the mandible of five rabbits by an extraoral approach. An LADC-stimulated 3.75 x 7 mm-titanium implant was placed in one site and an identical control implant was inserted on the contralateral side. A sterilized silicone-encased power pack producing 7.5 +/- 0.2 uA and 1.35 +/- 0.01 V was placed in a submandibular pouch. The active cathode lead was attached to the LADC implant and the anode was placed in the mandible 5 mm distal to the implant. Nonactive leads were similarly connected to the control implant. Twenty-eight days after placement, the implants were removed using a torque wrench, and the bone surrounding the implants was examined both microscopically and radiographically. RESULTS: The average force to initial rotation was 1,320 +/- 880 g/cm for the LADC-stimulated implants and 1,290 +/- 238 g/cm for the control implants. This was significantly different by t test (P = .94). Light microscopic evaluation demonstrated a mixture of compact and woven bone and fibrous tissue adjacent to both groups of implants. Histomorphometric analysis demonstrated an average percent of bone in relation to the total tissue adjacent to the control implants of 33.5 +/- 15.4 and 40.2 +/- 4.8 for the LADC-stimulated implants (not significantly different, t test, P = .39). CONCLUSION. It was concluded that LADC as used in this study does not positively affect the healing of bone. Its ability to enhance bone growth around titanium dental implants needs further investigation.

Animals↗
PubMed1995

Orthodontic forces increase tumor necrosis factor alpha in the human gingival sulcus.

The production of cytokines has been associated with the biology of tooth movement in animal populations. The purpose of this study was to measure tumor necrosis factor-alpha (TNF) directly in the human gingival sulcus before and after the application of an orthodontic force. To recover TNF from the sulcus, paramagnetic beads, coated with monoclonal antibodies for TNF, were introduced into the gingival sulcus of 50 teeth undergoing orthodontic tooth movement (by two force systems) in 20 patients. Retrieval was performed by a permanent magnetic device designed to fit the periodontal sulcus. The samples were taken before force application (controls), and at a fixed time after force application. The amount of immunoabsorbed TNF was quantified with an immunochemical assay. There was a greater than twofold increase in TNF recoverable from the gingival sulcus after application of orthodontic forces (mean of 12.9 ng vs 30.5 ng). A Student's t test for paired samples demonstrated statistical significance at p < 0.01. We conclude that the quantity of paradental TNF, found in human gingival sulcus, is elevated during tooth movement. The source may be from the adjacent gingiva, but more likely the compressed periodontal ligament and the resorbing bone adjacent to the root surface.

Adolescent↗
PubMed1995

Secondary bone grafting for unilateral alveolar clefts: a review of surgical techniques.

For the past 5 years we have been performing the closure of the oronasal fistula with alveolar bone grafting in the early-to-late secondary time period. The final decision as to whether early or late grafting should be done is based on if a grafting is needed to support the eruption of a functional lateral incisor. Generally the Moczair type buccal flap, with a "Z" release for wide clefts, is used for the buccal flap. This is combined with lateral releasing incisions on the palate for palatal closure. Separate nasal and oral closures are performed in all cases, with bone placed between the two layers in the alveolar defect. It is believed that this treatment sequence best fulfills the criteria for successful alveolar bone grafting outlined at the beginning of this chapter. Figure 8 demonstrates an alveolar bone grafting procedure in a 10-year-old girl just before eruption of the canine tooth treated with a buccal Moczair flap, lateral releasing incisions on the palate, two-layered closure, and the placement of an iliac bone graft.

Alveolar Process↗
PubMed1995

Respiratory emergencies in the dental office.

Respiratory emergencies are among the most common problems encountered in dental practice and are potentially among the most devastating. Therefore, they must be recognized rapidly and treated promptly. This article focuses on the clinically significant pathophysiology of respiratory emergencies, such that the practitioner can effectively identify the patients with a risk of developing a respiratory crisis and use this information to help provide rapid, effective therapy. Simple protocols are presented for the treatment of the most common respiratory emergencies.

Airway Obstruction↗
PubMed1994

Tumor necrosis factor-alpha as a biochemical marker of pain and outcome in temporomandibular joints with internal derangements.

OBJECTIVE: Previous studies have demonstrated the presence of tumor necrosis factor-alpha (TNF) in human temporomandibular joint (TMJ) synovial fluid. The present study continues the investigation of the role of TNF in TMJs with internal derangements. MATERIALS AND METHODS: Synovial fluid was obtained from 18 TMJs in 12 patients undergoing either arthroscopy (14 joints) or arthrotomy (four joints) for internal derangements. Standardized clinical data were collected preoperatively, intraoperatively, and postoperatively. RESULTS: When pain on palpation was absent, the mean preoperative TNF level was 14 +/- 6 ng/mL. When pain on palpation was present, the mean TNF level was 42 +/- 39 ng/mL (significant difference at P = .05). When the surgical outcome was poor, the mean preoperative TNF level was 26 +/- 9 ng/mL. When the outcome was within the stated guidelines for a favorable result, the mean TNF level was 12 +/- 7 ng/mL (significant difference at P = .05). In addition, a significant reduction (P = .05) in TNF following joint lavage (preoperative, 48 ng/mL to postoperative, 7 ng/mL) was found. CONCLUSIONS: The finding of a positive correlation between preoperative pain and TNF values suggests a biochemical basis for the origin of the pain associated with internal derangements. The relationship between preoperative TNF levels and surgical outcome suggests that the prognosis for surgery may be predicted by measuring biochemical markers of joint disease.

Adolescent↗
PubMed1988

Perfluoropropane gas, modified panretinal photocoagulation, and vitrectomy in the management of severe proliferative vitreoretinopathy.

Seventy-six consecutive patients with total rhegmatogenous retinal detachments and severe proliferative vitreoretinopathy underwent combined pars plana vitrectomy, lensectomy, panretinal photocoagulation, perfluoropropane gas (C3F8)/fluid exchange, and scleral buckling. Sixty-two (82%) of the patients had successful, sustained (greater than 12 months) posterior retinal reattachments at last examination. Of these 62 patients, 40 (65%) had complete retinal attachment, with no evidence of regrowth of periretinal membranes or redetachments following the initial procedure. In the remaining 22 cases with successful reattachment of the retina posterior to the equator, partial peripheral retinal detachments were observed. In 16 of the 22 cases, the detachments occurred entirely anterior to the boundary of the previously placed photocoagulation lesions. The posterior retina remained uninvolved, and no further treatment was needed. Reoperation was required in the other six patients to achieve sustained posterior retinal reattachment. Postoperative visual acuity ranged from 20/40 to bare light perception, with 69% of the anatomically successful cases obtaining functional visual acuity (greater than 20/400). Failures were related to reproliferation of fibrous membranes.

Adolescent↗
PubMed1981

Microsurgical management of macular epiretinal membranes (macular pucker).

Surgical management of selected macular epiretinal membranes is possible through the use of microsurgical pars plana vitreoretinal membranectomy. Visual improvement can be significant with resolution of traction retinal detachment and retinal distortion. Complications are similar to other forms of vitreous surgery. In a series of 9 selected cases with severe reduction of visual acuity secondary to macular pucker, microsurgical membranectomy was performed with encouraging results.

Adult↗
PubMed1981

Acute acquired toxoplasmosis.

A case of acute necrotizing retinitis with discrete involvement in the right posterior pole was followed undiagnosed until the patient developed endophthalmitis in the right eye, loss of consciousness, high fever, and a similar picture in the left eye. Treatment with sulfadiazine, pyrimethamine, and steroids brought about a prompt resolution. When the patient died from an unrelated cause, histopathology was performed showing Toxoplasma gondii in the brain.

Brain Diseases↗
PubMed1978

A technique for improving corneal clarity during retinal surgery.

To maintain corneal clarity during scleral buckling operations, the surgeon firmly rolls a dry cotton applicator across the edematous corneal surface, and the epithelial edema fluid is pressed out and absorbed by the applicator. This technique, which may be repeated a number of times, reduces the number of cases that require removal of the epithelium.

Absorption↗
PubMed1976

Human vitreous transplantation.

This lecture presents the experience in 200 implantations of human eye-bank vitreous through the pars plana of eyes with complicated retinal detachments. Though the success rate was modest, it shows that a large-bore instrument can be passed into the vitreous cavity of the eye with relative impunity and sets the stage for the present popular machine vitrectomy. In addition, the paper presents the author's experience with human vitreous transplantation by the 'open sky' transcorneal technique for otherwise hopeless vitreous opacities.

Eye Banks↗