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Biomedical subjects

R A Bays

Publications and source records attributed to R A Bays.

At least 37 records · Page 2Linked to original sources
PubMed1997

Cranial bone graft to reconstruct the mandibular condyle in Macaca mulatta.

PURPOSE: The purpose of this study was to evaluate the efficacy of cranial bone grafts to reconstruct the mandibular condyle in a nonhuman primate model. MATERIALS AND METHODS: The right mandibular condyle was resected in eight female, adult, nongrowing monkeys (Macaca mulatta) and the mandible was reconstructed with autogenous, full-thickness cranial bone harvested from the frontal area of the skull and stabilized with rigid fixation. Joint function, facial symmetry, and occlusion were evaluated preoperatively and over the course of 1 year postoperatively. The height of the bone graft was measured intraoperatively and at 1 year postoperatively. RESULTS: Seven monkeys survived for 1 year. The animals' weights were stable postoperatively. There were no statistically significant changes in maximal incisal opening or lateral excursion, as well as no statistically significant changes in facial symmetry or occlusion. On average, the total decrease in height of the graft was 0.7 +/- 0.9 mm (P = .07). CONCLUSION: After reconstruction of the mandibular condyle in Macaca mulatta, full-thickness cranial bone grafts provided a functional joint that resisted resorption. Cranial bone may therefore provide a suitable alternative to other autologous or alloplastic graft materials for reconstruction of the human mandibular condyle in nongrowing patients.

Analysis of Variance↗
PubMed1996

A comparison of questionnaire versus monofilament assessment of neurosensory deficit.

PURPOSE: Because neurosensory deficit is commonly reported by patients after orthognathic surgery, it is important to know how accurately patients can report their own sensory deficit. This analysis compares the results of objective neurosensory tests with the results of a subjective patient questionnaire. MATERIALS AND METHODS: Before and 6 months after bilateral mandibular sagittal ramus split osteotomy, 101 patients with class II facial deformities were asked to rate sensations of numbness or tingling in the area of the mental nerve. Simultaneously, they were objectively tested using monofilament neurosensory tests (light touch and brush stroke direction). RESULTS: More than 70% of patients subjectively reported neurosensory problems, but objective assessment identified neurosensory deficits in less than 60% of the patients. The sensitivity and specificity of the patients' subjective assessments were 75.3% and 52.8%, respectively, for the light touch test, and 77.9% and 59.8%, respectively, for the brush stroke test. CONCLUSIONS: It was concluded that when monofilament neurosensory testing is used as the gold standard, patients appear to overreport neurosensory problems; ie, the positive predictive value of patient reports is only 63.2%, resulting in frequent false positives.

Adolescent↗
PubMed1996

Skeletal change at surgery as a predictor of long-term soft tissue profile change after mandibular advancement.

PURPOSE: This study examined the time course of hard and soft tissue changes after mandibular advancement surgery and the association between skeletal changes as a result of surgery and subsequent soft tissue changes. PATIENTS AND MATERIALS: Subjects were enrolled in a randomized clinical trial of rigid versus wire fixation after sagittal split ramus osteotomy, with cephalometric data obtained before orthodontics, immediately before surgery and at 8 weeks, 6 months, 1 year, and 2 years postsurgery. This early report describes changes in 20 Caucasian female subjects who had completed all phases of the study; these were not segregated by fixation method. Cephalometric changes were referenced to a cranial base coordinate system. Differences in soft and hard tissue changes among time intervals were examined using analysis of variance; the associations between immediate surgical change in chin landmarks and subsequent short- and long-term soft and hard tissue changes were examined using linear regression analysis. RESULTS: Soft and hard tissue mandibular structures were positioned anteriorly and inferiorly during surgery; the horizontal and vertical hard tissue mandibular changes were stable for 2 years after surgery (P > .30), as were the vertical soft tissue changes (P > .08). There was horizontal relapse of the lower lip and the inferior sulcus (P < .03) by 8 weeks; no horizontal relapse was detected in soft tissue chin points for up to 2 years after surgery. The time course of changes in osseous pogonion was more strongly predicted by the amount of surgical osseous chin change than were changes in soft tissue chin projection. CONCLUSIONS: Prediction of changes in soft tissue chin projection after mandibular advancement surgery is less certain as time from surgery increases and less certain than the prediction of changes in bony chin projection.

Adolescent↗
PubMed1996

The effect of local anesthesia with vasoconstrictor on gingival blood flow during Le Fort I osteotomy.

PURPOSE: In earlier studies, it has been documented that maxillary gingival blood flow (GBF) decreased significantly during the intraoperative course of a Le Fort I osteotomy. It was not clear, however, whether the observed decrease in GBF was caused by the osteotomy or by the use of local anesthetic with vasoconstrictor (LA + V). The purpose of this study was to measure the effect of LA + V on GBF during Le Fort I osteotomy using laser Doppler flowmetry (LDF). PATIENTS AND METHODS: Using a randomized clinical trial study design, patients undergoing Le Fort I osteotomy were assigned to either a treatment (group 1, LA + V used) or a control group (group 2, LA + V not used). The predictor variable was group assignment (LV + V used or not used). The outcome variable was mean maxillary GBF. Maxillary GBF was recorded at predetermined times during the operation. Other study variables included age, sex, single- or double-jaw surgery, estimated blood loss, direction and magnitude of maxillary movements, temperature, pulse, mean blood pressure, O2 saturation, and duration of operation. RESULTS: There were 19 patients in group 1 (LA + V used) and 15 patients in group 2 (LA + V not used). In both groups, mean maxillary GBF decreased significantly during the operation (group 1, 33.3 +/- 13.1 to 16.9 +/- 16.1 mL/ min/100 g tissue, P = .015; and group 2, 48.2 +/- 17.1 to 15.5 +/- 7.6 mL/min/100 g tissue, P = .001). The decrease in GBF occurred much earlier in group 1. By an average of 2.3 hours into the operation, the mean GBF was equivalent in both study groups (group 1, 10.6 +/- 8.6, and group 2, 13.1 +/- 9.4 mL/min/100 g tissue, P = .44). CONCLUSIONS: The results of this study confirm earlier findings that mean maxillary GBF decreases significantly during the intraoperative course of a Le Fort I osteotomy. In addition, LA + V significantly affects GBF during the early phase of the operation. Its effect, however, dissipates between the time of soft tissue dissection and maxillary downfracture.

Adult↗
PubMed1996

Signs of temporomandibular disorders in patients with horizontal mandibular deficiency.

This study assessed the relationship between temporomandibular disorders (TMD) and malocclusion in a group of 102 patients with horizontal mandibular deficiency who had elected mandibular advancement surgery. The prevalence of TMD as reflected by the overall Craniomandibular Index, Dysfunction index, and Muscle index scores was within the range of non TMD populations (mean Craniomandibular Index = 0.14; mean Dysfunction index = 0.12; mean Muscle index = 0.15). Forty-two percent of the patients exhibited essentially no signs of TMD, 7.8% had primarily muscle tenderness to palpation, 36.3% had joint sounds with or without temporomandibular joint tenderness, and 13.7% had combined muscle-joint signs. There were no convincing correlations among any of the cephalometric variables and Craniomandibular Index, Dysfunction index, and Muscle index scores. A subgroup of 30 of this patient population was evaluated both before and during orthodontic treatment just prior to surgery. No statistically significant changes were found in Craniomandibular Index, Dysfunction index, or Muscle index scores. Thus, a period of orthodontic treatment in these patients does not appear to increase the probability of TMD.

Adolescent↗
PubMed1994

Intraoperative assessment of maxillary perfusion during Le Fort I osteotomy.

Intraoperative maxillary blood flow was measured using laser Doppler flowmetry (LDF) in two groups of patients undergoing orthognathic surgery. Group 1 (n = 14) consisted of patients undergoing Le Fort I osteotomy and group 2 (n = 8) consisted of patients undergoing isolated mandibular osteotomies. In group 1, the mean gingival blood flow (GBF) decreased significantly over time during the course of the operation from 29.5 mL/min/100 g of tissue to 13.2 mL/min/100 g of tissue (P = .0001). The mean GBF did not change significantly over time in group 2 (P = .39). The results of this study demonstrate that 1) LDF may be used to measure intraoperative GBF during Le Fort I osteotomy with an acceptable level of variability, and 2) maxillary GBF decreased significantly over time during Le Fort I osteotomy procedures.

Adult↗
PubMed1994

Repair of temporomandibular joint disc perforation using a synovial membrane flap in Macaca fascicularis monkeys: light and electron microscopy studies.

Previous studies have demonstrated that experimentally produced perforations in the discs of Macaca fascicularis monkeys lead to osteoarthrosis. Synovial membrane hyperplasia also was demonstrated in monkey and human joints with disc perforations. The hypothesis was advanced that a synovial flap obtained from within the affected joint would be the most appropriate tissue to repair chronic disc perforation. To test this hypothesis, four adult M fascicularis monkeys were anesthetized and 4- to 6-mm perforations were made in the posterolateral aspects of the avascular discs bilaterally. The wounds were sutured leaving the perforations open, and the animals were fed their normal diet. After 4 weeks, one joint in each monkey was reopened and a repair was performed using a double-layered flap from the synovial lining of the superior and inferior recesses. Four weeks after repair, the animals were killed and the temporomandibular joints (TMJs) were removed en bloc and decalcified. The joints were sectioned into lateral, middle, and medial sections and were photographed using a stereomicroscope and then processed for light and electron microscopy. The same processing was done to four intact joints that were used as controls. Eight weeks following perforation, the joint components showed degenerative changes consistent with osteoarthritis. Close to the perforations the disc showed loss of collagen, vacuolation of extracellular matrix, accumulation of dense proteoglycan-like material, and the appearance within the disc of type A or macrophage-like cells of the synovium. The discal tissue away from the perforation showed high cellularity and vascularity. The temporal and condylar surfaces showed denudation, fibrillation, osteophytes, and chondrocytic clustering, all characteristics of osteoarthrosis. The surgically repaired discs were intact and the articular surfaces showed no degenerative changes. Discal collagen was restored and appearance of myofibroblasts and elastogenesis were a consistent feature of the repaired disc. The vascularity of the condylar cartilage of the repaired joints appeared similar to that of embryonic cartilage. The reversibility of the degenerative alterations following discal repair in this experimental model should provide the basis for a rational and useful method for surgical repair of TMJ disc perforation using intraarticular synovial tissue.

Animals↗
PubMed1994

Validation of air plethysmography, photoplethysmography, and duplex ultrasonography in the evaluation of severe venous stasis.

PURPOSE: The purpose of this study was to validate the diagnostic capabilities of the most commonly used noninvasive modalities for evaluation of chronic venous insufficiency. METHODS: Twenty limbs in 20 patients were studied with air plethysmography (APG), photoplethysmography (PPG), and duplex ultrasonography. Ten limbs (group 1) were clinically without any venous disease. Group 2 consisted of 10 limbs with severe, class 3 venous stasis. Duplex ultrasonography, complemented with Doppler color-flow imaging was used to examine the superficial and deep venous systems to identify reflux. RESULTS: Ultrasonography identified deep venous reflux in eight of 10 limbs in group 2. Severe superficial reflux was identified in the two remaining limbs. Seven limbs with deep reflux also demonstrated severe superficial reflux. Superficial venous reflux was identified in one leg in group 1. APG accurately separated normal limbs from those with reflux. Parameters that were significantly different (p < 0.05) between the two groups were the venous filling index, (group 1 = 1.37 +/- 1.16 ml/sec, group 2 = 29.5 +/- 6.2 ml/sec.), venous volume (group 1 = 107 +/- 10.1 ml, group 2 = 220 +/- 22.5 ml), ejection fraction (group 1 = 52.5% +/- 2.3%, group 2 = 32.5% +2- 4.6%), and residual volume fraction (group 1 = 21.4 +/- 2.0%, group 2 = 52.1% +/- 2.5%). PPG refill times were significantly shortened in group 2 versus those of group 1 (6.4 +/- 0.89 sec vs 20.2 +/- 1.1 sec). The sensitivity of PPG refill times to identify reflux was 100%, but the specificity was only 60%, whereas the sensitivity and specificity for the residual volume fraction was 100%. The venous filling index was able to identify reflux and determine whether only superficial reflux was present with a sensitivity of 100% and a specificity of 90%. The kappa coefficient of agreement between duplex scanning and APG was 0.83, whereas between duplex and PPG it was only 0.47. CONCLUSION: APG accurately identifies limbs with and without venous reflux when compared with duplex ultrasonography. APG is a better method of evaluating clinically significant venous reflux than PPG. PPG is a sensitive method of detecting reflux, but the specificity is poor, and PPG refill times cannot accurately predict the location of reflux. The combination of APG and duplex ultrasonography provides the best means of assessing venous reflux.

Adolescent↗
PubMed1993

Risk factors for infection following operative treatment of mandibular fractures: a multivariate analysis.

Utilizing a retrospective study design and a study sample of 284 consecutive patients, we measured the association between five different risk factors and the development of infection following the operative management of mandibular fractures. The five risk factors analyzed were age, sex, number of fractures per patient, time from admission to treatment, and treatment modality. The overall infection rate was 5.3 percent. The infection rate for each treatment modality was (1) 0 percent for closed reduction, (2) 20.0 percent for open reduction and internal fixation with wire osteosynthesis, and (3) 6.3 percent for open reduction and rigid internal fixation. To measure the association between the various risk factors and postoperative infection, we used multivariate logistic regression. After controlling for potential confounding variables, the only risk factor statistically associated with postoperative infection was treatment modality.

Adult↗
PubMed1992

Surgically assisted rapid palatal expansion: an outpatient technique with long-term stability.

This study presents the results of surgically assisted rapid palatal expansion done on an outpatient basis in 19 patients with a mean age of 30 years. Postsurgical and postorthodontic evaluation (mean, 2.4 years) showed a mean relapse rate of 8.8% in the canine region, 1% in the premolar region, and 7.7% in the molar region. These results show that the surgical procedure is feasible on an outpatient basis and the technique, as outlined, yields a stable long-term result.

Adolescent↗
PubMed1991

A new mandibulotomy technique for the dentate patient.

Past mandibulotomy techniques, useful for surgical access to pathology of the head and neck, are complicated by postoperative malocclusion when performed on dentate patients. Malocclusion results from closure of the gap created by the saw blade during reconstruction. A new method of mandibulotomy bicortically splits the symphysis using an osteotome, with modifications to spare healthy dentition. The bicortical split osteotomy allows the hemimandibular segments to be approximated, accurately aligned, and rigidly fixed with three bone screws and a dental arch bar.

Bone Screws↗
PubMed1991

The use of bupivacaine in elective inguinal herniorrhaphy as a fast and safe technique for relief of postoperative pain.

The intraoperative use of local anesthetic agents to decrease postoperative pain has been used in many types of procedures. Most of these techniques involve needle injection of anesthetic and result in a low but troublesome incidence of complications. In this study, we evaluated the reliability, safety, and efficacy of a technique emphasizing bathing of tissues with anesthetic rather than needle injection for relieving postoperative pain. Thirty consecutive patients undergoing outpatient elective inguinal herniorrhaphy with general anesthetic were prospectively randomized into four treatment groups. Group 1 received 0.5 per cent bupivacaine plus epinephrine 1 to 200,000; group 2, 0.5 per cent bupivacaine; group 3, normal saline solution, and group 4, no treatment. At the end of the repair, one-third of the test solution (approximately 5 milliliters) was bathed along the spermatic cord throughout its length in the inguinal canal. The external oblique aponeurosis was closed superficial to the cord structures and another one-third of the solution was instilled into the wound. Just prior to the end of skin closure the remaining solution was instilled subcutaneously. No needles were used to instill the solutions and they were not suctioned or removed from the wound. Data collection consisted of an analog type of patient questionnaire allowing subjective assessment of postoperative pain at various time intervals during the first 20 hours postoperatively. Pain medication provided was propoxyphene, 100 milligrams and acetaminophen, 650 milligrams every three hours as needed. Total doses of pain medication for the study period and the time to first pain medication requirement were obtained. Results were analyzed using analysis of variance, and Wilcoxon ranked sums test. Patients in group 1 (0.5 per cent bupivacaine with epinephrine) exhibited significantly less pain than those in groups 3 (saline solution) and 4 (control) for more than 12 hours postoperatively. Patients in group 2 (0.5 per cent bupivacaine) likewise experienced less pain than those in groups 3 and 4 through seven hours. The patients receiving saline solution were not significantly different than those in the control group throughout. Objectively, groups 1 and 2 required fewer total doses of pain medication and waited longer before requesting oral pain medication postoperatively compared with those in the control group. No complications occurred that could be attributed to the technique. The results of this study indicate that the bathing of wounds with 0.5 per cent bupivacaine with or without epinephrine 1:200,000 is a safe and effective method of decreasing postoperative pain for several hours in patients undergoing elective inguinal herniorrhaphy.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1990

Fatty change in the human temporomandibular joint disc. Light and electron microscopy study.

Joint pain has been associated with fatty infiltration of the knee articulation. The purpose of this study is to report on the histopathological findings, especially fatty changes, that are seen in surgical specimens from the temporomandibular joints (TMJ) of patients that had persistent pain after non-surgical therapy. Forty plicated TMJ retrodiscal samples from 25 patients were used in this study. The patients were previously treated with splints for variable periods but not less than 2 months. The specimens were obtained by 2 surgeons using standard TMJ plication techniques. Control disc specimens were obtained from normal appearing cadaveric TM joints. Samples were immediately immersed in glutaraldehyde and processed for light and electron microscopic examination. The specimens were composed mainly of moderately dense tissue with cells that appeared fibroblastic and intermittent chondrocytic type cells. Fatty change, exclusively in association with the perivascular areas, was observed in 27 of 40 specimens. Electron microscopy showed fibroblasts, as well as large fat inclusions adjacent to elastin macroglobules. Fatty infiltration of the TMJ has been interpreted as a degenerative change. It is postulated that kinins and prostaglandins generated in the fat pads can pass freely in tissue fluid to adjacent, highly innervated structures thus leading to joint pain. It is further postulated that the finding of associated elastin with fatty deposition is similar to the atherosclerotic changes encountered in large blood vessels and the aorta.

Adipose Tissue↗
PubMed1989

Temporomandibular joint noises in infants review of the literature and report of cases.

Temporomandibular joint (TMJ) function and dysfunction in infants and children are poorly understood. Some reports of dysfunction in children and adolescents have appeared in the literature; however, no contemporary reports of TMJ dysfunction in infants have been published. Here we describe three cases of TMJ noises that may represent an anatomic abnormality. Patients' ages at onset were 3 days, 5 months, and 6 months. All noises occurred in the apparent absence of trauma and without other clinical findings. Two cases resolved spontaneously over a 2- to 5-month period. One case is still occurring, but the frequency is decreasing with age. In all cases there was no history of distress on the part of the child during mandibular movements or when the noises occurred. Included is a review of the literature and hypotheses of the etiology of TMJ noises in infants.

Female↗