Anatomy of cusps of posterior teeth and their fracture potential.

Fracture of cusps on posterior teeth, especially those carious or restored, is a major cause of tooth loss, Nonfunctional cusps fracture more often than the functional; mandibular cusps fracture more often than maxillary cusps. This study examined functional and nonfunctional cusps of the maxillary and mandibular posterior teeth in four different parameters; (1) buccolingual width, (2) angle of cuspal inclination, (3) thickness of enamel, and (4) angle of inclination of the dentinoenamel junction. Measurements of functional cusps, except those in maxillary premolars established differences that may explain the frequency of frequency of fracture. These parameters of functional and nonfunctional cusps suggest that the cuspal anatomy has a relationship to the fracture potential of cusps.

Arthroscopic resection of olecranon and prepatellar bursae.

This article presents a new method of excision of olecranon and prepatellar bursae using an arthroscopic technique. Six cases, three in each anatomic location, are retrospectively reviewed with an average follow-up of 6.25 months (1.5-15 months). When the etiology of the bursitis was traumatic, all four cases did well. Unsatisfactory results were obtained, for both a patient with CREST syndrome (Calcinosis, Raynaud's phenomenon, Esophageal hypomobility, Sclerodactyl, Telangietasia) and a patient with gouty bursitis. The results from this limited series would suggest reserving this technique for those cases of bursitis secondary to trauma, and not responding to conservative treatment.

The skeletal stability of Le Fort I downfracture osteotomies with rigid fixation.

Twenty subjects receiving Le Fort I downfracture osteotomies stabilized with rigid fixation were studied for relapse. The analysis was based on longitudinal cephalometric radiographs taken within 2 weeks presurgically, 1 week postsurgically, and after a minimum period of 6 months postsurgically. Vertical and sagittal changes in the maxilla were evaluated in reference to the Frankfort horizontal plane. It was found that the mean postsurgical relapse was minimal and not significant. It was smaller than that reported for patients who had received stabilization of the maxilla with intraosseous and maxillomandibular wiring. It was concluded that the rigid fixation technique is dependable and yields stable postsurgical results in the maxilla.

Wrist pain and distal growth plate closure of the radius in gymnasts.

Three cases in which wrist pain developed in skeletally immature competitive gymnasts are presented. In all three cases there is radiographic evidence of premature growth plate closure, resulting in shortening of the radius and alterations in the normal distal radioulnar articulation. Repetitive compressive loading of the distal growth plate of the radius is proposed as a potential etiology of this condition. Treatment goals, including an example of successful ulnar shortening, are reviewed. The authors suggest activity limitation with the onset of symptoms, in order to avoid the permanent structural changes observed in our patients.

Evaluation of single-photon-counting measurements of excited-state lifetimes.

An extremely short instrumental response function for a single-photon-counting system has been obtained by using a low-jitter photomultiplier tube, fast amplification of the single photoelectron pulse from this photomultiplier, a constant fraction discriminator with a wide bandwidth input, and a stable reference timing signal. This synchronously mode-locked laser system has been shown to be capable of measuring the fluorescence lifetimes of compounds from 66 psec to 4.5 nsec. The estimated error in these determinations is 6% or 10 psec, whichever is greater. This apparatus has proved itself to be superior to the previously used nitrogen flashlamp apparatus for the determination of subnanosecond lifetimes. The validity of using deconvolution to determine lifetimes shorter than the instrumental response function has been verified.

Ultrasonographic demonstration of a placental maternal lake.

A 30 year old woman was seen at 32 weeks of gestation because of severe abdominal pain. A sonogram revealed an irregular, 5 cm-diameter cystic structure in the placenta. Examination of the placenta after cesarean section showed an extremely large maternal lake.

Follow-up of intrauterine transfused surviving children.

The long-term effects of intrauterine transfusion (IUT) are still being assessed since the procedure was first reported in 1963. Therefore, we undertook a follow-up study on the survivors of 57 infants who received IUT's between 1966 and 1975. Forty-two infants were born alive, but 15 died in the neonatal period. Overall survival was 27/57 (48%). An extensive follow-up examination was carried out at age 22 months to 10 years in 21/27 survivors. Height was below the third percentile in one child and head circumference above the mean and 2 SD in another. Of 21 children, 19 had normal vision, one was slightly myopic, and one had hyperopia. One child had unilateral high-frequency hearing loss. All had normal EEG's and none have mental retardation but 2/21 have "major" and 6/21 have "minor" neurologic signs. No evidence of passive antibody transfer was found, but minor disturbances of immunoglobulin levels were present.

Real-time ultrasound as an aid in intrauterine transfusion.

Real-time ultrasound was used as an aid in intrauterine transfusions for patients with Rh isoimmunization. It was preferred to fluoroscopy and x-ray control to identify the placental site and fetal abdomen and to direct the insertion and placement of the transfusion needle. The technique was used 22 times in 12 patients and resulted in increased efficiency and safety, including decreased radiation to the fetus.

Ultrasound as an aid in intrauterine transfusion.

Although the number of patients with Rh isoimmunization in pregnancy has been decreasing in recent years, intrauterine transfusion is still an important form of therapy for those patients whose infants have erythroblastosis. We have used both gray-scale and real-time ultrasonography for the last ten cases in which intrauterine transfusion was necessary. These techniques were used in preference to fluoroscopy and x-ray control to identify the placental site and fetal abdomen and to direct the insertion and placement of the transfusion needle. We were able to visualize the needle when it entered the amniotic cavity and the fetal abdomen. The technique afforded continuous visualization and a cross-sectional image of the fetus, steps which increase the efficiency and safety of the procedure and decrease radiation to the fetus.