Trabecular bone remodeling and balance in primary hyperparathyroidism

The total remodeling sequences in 19 primary hyperparathyroid patients and 16 approximately age-matched and sex-matched controls were reconstructed from histomorphometric analyses of bone specimens obtained after intravital tetracycline double labeling. In the primary hyperparathyroid group the total amount of work performed by resorptive cells was reduced, as indicated by the significantly lower three-dimensional mononuclear and preosteoblast-like cell resorption depths (35.8 microns vs 44.5 microns in normals, P less than 0.01 and 45.3 microns vs 56.6 microns in normals, P less than 0.01, respectively). The active resorption period (i.e., the function period for osteoclasts and mononuclear cells) was reduced to 19 days compared to 29 days in normals (P less than 0.05), but no difference with respect to bone resorption rates could be demonstrated between the two groups. The median bone formation period (Sigmaf) in primary hyperparathyroid patients was not different from the value obtained in normals (172 days vs 134 days, respectively), and the matrix appositional rate (Ama), as well as the mineralization lag time (tm), were also unchanged. The initial mineralization rate (Ami(i)) was not significantly different from the value obtained in normals, but averaged over the total bone formation period, a reduced mineralization rate could be demonstrated (0.32 micron3/micron2 per day vs 0.46 micron3/micron2 per day in normals, P less than 0.01). The measured final three-dimensional thickness of bone formed during Sigmaf (mcwTm) was reduced in the primary hyperparathyroid group (51.1 microns vs 55.9 microns in normals, P less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)     

Anatomy and development of the pterygopalatomaxillary region, studied in relation to Le Fort osteotomies

An understanding of the anatomy and postnatal development of the pterygomaxillary region is needed as a basis for timing and completion of Le Fort osteotomies. The present study included a macroscopic and microscopic study of human skull and autopsy material, both materials representing different developmental stages. Finally, Le Fort I procedures were completed on adult cadavers and the pterygomaxillary region studied histologically. The skull material demonstrated an increasing association between the palatine bone and adjacent bones. Disarticulation was possible only in the infantile period; in the late juvenile and the adolescent stages, disarticulation was accompanied by fractures of the heavily interdigitated osseous surfaces. The histological studies confirmed the marked complexity of the suture, and our findings suggest that the palatine bone acts as a buffer between these areas with their differing intrinsic growth patterns. The remodeling processes in the area seem to reflect different functional demands of the bony pharynx and the maxillary complex. These findings, in conjunction with the significant variations in the gross anatomy of the pterygomaxillary area combined with the location of the actual osteotomy in simulated Le Fort I procedures, force consideration of placement of the posterior osteotomy through the maxillary sinus rather than through the pterygomaxillary fissure in adults. If Le Fort procedures are to be completed in children, probable interference in facial growth is of major concern. Therefore the timing of Le Fort procedures before adolescence must be reconsidered.     

Changes in vitamin D metabolites and bone histology in rats during recovery from rickets

Summary The relative roles of 25-hydroxyvitamin D (25-OHD), 1,25-dihydroxyvitamin D (1,25-(OH)₂D) and 24,25-dihydroxyvitamin D (24,25-(OH)₂D) in bone mineralization are largely unknown. Young vitamin D depleted rats were fed increasing amounts of vitamin D and grouped radiologically in accordance with the rat line test. They ranged from severely rachitic to normal. Radiology was correlated with serum levels of 25-OHD, 1,25-(OH)₂D, 24,25-(OH)₂D, ionized calcium, magnesium, and phosphate, with bone histology, and with the total mineral content of the animals. Serum 1,25-(OH)₂D rose in a linear fashion to supranormal values during bone healing and correlated with the radiological degree of rickets. Serum 25-OHD was below detection limit in the most rachitic and low in the radiologicall normal rats, whereas 24,25-(OH)₂D was low in all groups. These two metabolites showed no correlation with the radiologic, histologic or biochemical parameters. In rachitic rats, 1,25-(OH)₂D appears to play a major role in bone healing and possibly exerts a direct effect on bone cells. It cannot be ruled out, however, that the effect is mediated through a rise in serum levels of calcium and phosphorus, although signs of bone healing were seen in the presence of a subnormal calcium x phosphorus product. Initiation of mineralization can take place with unmeasurable 25-OHD, and 24,25-(OH)₂D seems to be without importance.     

Is minitracheotomy a simple and safe procedure? A prospective investigation in the intensive care unit

Patients with imminent respiratory failure due to sputum retention were assessed for minitracheotomy (MT). MT was considered potentially useful in 79 patients but only attempted in 73, 54 men and 19 women, aged 23–81 years (median 65 years). Insertion of the cannula failed in 4 cases. Sputum retention and atelectasis were successfully treated in 87% (N=60). Treatment by MT in medical and neurological patients seems as effective as in surgical patients (success rate 81% versus 90%). The frequency of complications was 16%. Most complications were insignificant and occurred during cannulation, but a few severe complications were seen. To minimize the number of these it is essential that MT is done only by doctors who are familiar with the procedure. MT can be recommended for treatment of sputum retention and atelectasis in surgical and medical/neurological intensive care patients with preserved cough function.     

Spontaneous rupture of the aorta in Marfan's syndrome

Summary 5 cases of Marfan's syndrome in young men all of whom had died suddenly and unexpectedly of spontaneous rupture of a dilated, thin-walled ascending aorta are described on the basis of autopsy material. Histological examination of the aorta revealed in all cases characteristic degenerative changes with cystic degeneration of the elastic membranes.Over a 5-year period, these cases comprised 8% of the cases of sudden unexpected death in the age group 10–29 years referred for autopsy. Forensic medicine can help to establish the pathological and enzymopathological basis of Marfan's syndrome.

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Zusammenfassung 5 Fälle von Marfans Syndrom bei jungen Männern, die alle plötzlich unerwartet an einer spontanen Ruptur der Aorta ascendens starben, werden auf der Basis von Autopsiematerial beschrieben. In allen Fällen wurden charakteristische somatische Veränderungen gefunden.Histologische Untersuchungen der Aorta enthüllten in allen Fällen charakteristische degenerative Veränderungen mit mangelhaften elastischen Membranen. In der Media wurden cystische Degenerationen sowie Ablagerungen eines strukturlosen Materials gefunden, das mit mehreren Färbungsmethoden positive Mucinreaktion zeigte. Die eventuellen prämortellen diagnostischen Möglichkeiten werden besprochen, ebenfalls werden Ähnlichkeiten des Syndroms mit anderen seltenen Krankheiten diskutiert.Über eine 5jährige Periode machten diese Fälle 8% sämtlicher Fälle von plö tzlich unerwartetem Tod in der Altersgruppe 1029 Jahre aus, die im Gerichtsmedizinischen Institut in Arhus obduziert wurden. Da diese Todesart relativ häufig für Patienten mit Marfans Syndrom ist, müßte die Gerichtsmedizin in Zukunft zur Beleuchtung der pathologischen und enzymopathologischen Verhältnisse des Leidens beitragen können.

     

Clinical comparison between a resin-reinforced self-cured glass ionomer cement and a composite resin for direct bonding of orthodontic brackets. Part 2: Bonding on dry enamel and on enamel soaked with saliva

The purposes of this investigation were to compare the clinical performance of a resin-reinforced self-cured glass ionomer cement to a standard composite resin in the direct bonding of orthodontic brackets when bonded onto: a) dry teeth and b) teeth soaked with saliva. The two bonding agents were compared using a split-mouth design. In that, both systems were used for direct bonding of stainless steel brackets in every patient. Thirty-eight consecutive patients with fixed appliances were followed for a period of 12 months. The patients were randomly divided into two groups: group A (11 patients) and group B (27 patients). In group A, the performance of 220 stainless steel brackets was evaluated: 110 brackets were bonded with GC Fuji Ortho glass ionomer cement (GC Industrial Co., Tokyo, Japan) onto dry teeth, and 110 bonded with System 1+ composite resin (Ormco Corp., Glendora, CA). In group B, the performance of 540 stainless steel brackets was evaluated: 270 brackets were bonded with GC Fuji Ortho onto teeth soaked with saliva, and 270 bonded with System 1+. In group A, GC Fuji Ortho recorded an overall failure rate (34.5%) significantly higher (p < 0.05) than System 1+ (9%) when applied onto completely dry teeth. Conversely, in group B, no statistically significant differences (p > 0.05) between the failure rates of the two bonding agents were found when GC Fuji Ortho was used on teeth soaked with saliva. It was concluded, therefore, that GC Fuji Ortho shows clinically acceptable bond strengths when bonded onto moist teeth, but not when used on dry enamel. Both bonding agents failed mostly at the enamel/adhesive interface, without causing any enamel damage.     

A histomorphometric evaluation of factors influencing the healing of bony defects surrounding implants

PURPOSE: The authors' aim was to perform a histomorphometric study of the healing of bone defects created adjacent to titanium and hydroxyapatite (HA) -coated implants and covered with either a resorbable or a nonresorbable membrane in combination with different filler materials and to evaluate to what degree coating, membrane, and/or filler influenced the healing of the defects. MATERIALS AND METHODS: Posterior teeth were extracted from the mandibles of 10 baboons, and 12 implants were placed in each animal in the edentulous areas. The implants were either titanium or HA-coated, the membranes were either Vicryl, Gore-Tex, or Resolut, and the filler was either demineralized freeze-dried bone (DFDB), autogenous bone, or Biocoral. The implants were observed for either 3, 6, 9, 12, or 18 months. The volume of newly generated tissue and the relative contribution of bone, marrow, and filler were evaluated, as was relative extension of resorption, formation, and quiescent surface. RESULTS: The results indicated that autogenous bone is still the gold standard, but both the DFDB and Biocoral compared favorably to it. Both filler materials were being gradually replaced by bone; this process was not yet finished at 18 months postsurgery. DISCUSSION: Since even the sterilization of DFDB cannot exclude the possibility of a disease transmission, it is important to find an appropriate substitute. Both filler and membranes contributed to the re-establishment of the original volume; better results were achieved with the Vicryl and Gore-Tex membranes than with the Resolut. Biocoral can be considered an effective material. CONCLUSION: A bony defect is not necessarily a contraindication for the placement of an implant. (More than 50 references.)     

Clinical comparison between a resin-reinforced self-cured glass ionomer cement and a composite resin for direct bonding of orthodontic brackets Part 1: wetting with water

The purpose of this study was to compare the clinical performance of a resin-reinforced self-cured glass ionomer cement to a standard composite resin in a split mouth design, by using both systems for direct bonding of orthodontic stainless steel brackets in every patient. Forty eight patients (34 females and 14 males, of which 29 were adults > 18 years of age) with fixed appliances were followed for a mean period of 10 months (range 4–16 months). The performance of 864 stainless steel brackets was evaluated: 404 brackets were bonded with GC Fuji Ortho glass ionomer cement (GC Industrial, Tokyo, Japan) onto teeth soaked with water, and 460 were bonded with System 1 + composite resin (Ormco, Glendora, CA). System 1 + recorded an overall failure rate (18.2%) significantly higher (p < 0.05) than GC Fuji Ortho (7.9%). There were no statistically significant differences (p> 0.05) between the failure rates in the upper and lower arches with either material. Both in the upper and lower arches, System 1 + exhibited a failure rate significantly higher (p < 0.05) than GC Fuji Ortho. When the bonding performance of the six anterior teeth was compared with first and second premolars, no statistically significant differences were found (p> 0.05) between bonding agents in either arch. System 1 + exhibited a failure rate significantly higher (p < 0.05) than GC Fuji Ortho, both in the anterior and posterior segments. Both bonding agents failed mainly at the enamel—adhesive interface, without causing any damage to the enamel.