Cephradine (Velosef) penetration of mandibular bone

The concentration of cephradine in serum and mandibular bone was assayed in 28 patients undergoing 3rd molar surgery following a single 1 g intravenous injection. Serum and cortical bone samples taken simultaneously, contained mean cephradine concentrations of 42.11 micrograms/ml and 2.61 micrograms/g respectively. These results, when compared with those reported for other bony sites including the femoral head and knee, show a reduced bone penetration with a bone-to-serum ratio of approximately 0.06:1.

[Importance of masseter insertion surface in different mammal groups]

The objective of this study is to compare the strength of the masseter muscle in various mammals by calculating the ratio between insertion area of the masseter and total mandibular surface. We will also determine the factors capable of modifying the insertion area of this masticatory muscle.

Distribution of fluoride across cementum, dentine and alveolar bone in rats

This study was undertaken to determine the fluoride distribution in cementum and neighboring hard tissues of the rat after different levels of fluoride administration via the drinking water. Specimens of cementum with underlying dentine and adjacent bone were removed from the distal roots of the first lower molars. The fluoride distribution in each specimen was determined in samples removed sequentially using an abrasive microsampling technique. Fluoride concentrations were highest at or near the surface and decreased towards the interior of cementum, dentine and alveolar bone in both control and experimental groups. With increasing fluoride intake, concentrations increased throughout the tissue. The distribution patterns of fluoride in cementum of contralateral teeth from the same animal were similar. Fluoride concentrations in cementum were higher than those of dentine and alveolar bone.

Effects of maternal caffeine with zinc intake during gestation and lactation on bone development in newborn rats

On day 9 of gestation, pregnant dams were randomly divided into 3 groups. Dams of group 1 were fed a 20% protein diet as a control. Dams of group 2 were fed a 20% protein diet supplemented with caffeine. Dams of group 3 were fed a 20% protein diet supplemented with caffeine and zinc. The amount of caffeine added to the maternal diet was 2 mg/100 g body weight; the amount of zinc was 0.6 g/kg of diet. At birth, pups were mixed within each group, and 8 randomly selected pups from each group were assigned to each dam of the respective group and were continuously fed the same diet. On day 15, the pups were killed and cranial bones, mandibles and femurs removed. The bones were measured, and the mineral content of the mandibles and femurs was determined. Although there were no differences in the dimensions of the cranial bones among the groups, the measurements and mineral content of the mandibles and femurs were consistently affected by the caffeine in the diet. On the other hand, supplementation of the caffeine-added diets with zinc led to greatly improved bone development, reaching values up to or beyond control levels. Thus zinc supplementation of a caffeine diet given to the dams during gestation and lactation can favourably influence the otherwise impaired bone development of their offspring.

Maturation of bone and dentin matrices in rats flown on the Soviet biosatellite Cosmos 1887

We have studied the chemistry, hydroxyapatite crystal size, and maturational changes in bone and dentin from rats exposed to microgravity for 12 days in a Soviet biosatellite (Cosmos 1887). Bone ash was reduced in vertebrae (L5) but not in the non-weight-bearing calvaria or mandibles. All tissues had a relatively normal percentage composition of Ca, P, and Mg. Nevertheless, flight rat calvaria and vertebral tissues tended to exhibit lower Ca/P and higher Ca/Mg ratios that any of their weight-matched controls groups, and gradient density analysis (calvaria) indicated a strong shift to the fractions lower specific gravity that was commensurate with impaired rates of matrix-mineral maturation. X-ray diffraction data were confirmatory. Bone hydroxyapatite crystal growth in the mandibles of flight rats was preferentially altered in such a way as to reduce their size (C-axis dimension). But in the mandibular diastemal region devoid of muscle attachments, flight rat bone and dentin were normal with respect to the Ca, P, Mg, and Zn concentrations and Ca/P and Ca/Mg ratios of age-matched controls. These observations affirm the concept that while microgravity most adversely affects the maturation of newly formed matrix and mineral moieties in weight-bearing bone, such effects occur throughout the skeleton.

Metal release from plates used in jaw fracture treatment. A pilot study

This study investigated the occurrence of corrosion associated with the use of metallic implants to stabilize jaw fractures. Three different types of plates, Co-Cr and Ni-Cr alloys and Titanium, were connected in vivo to the mandibular bone surface of monkeys (Cercopithecus aethiops). The animals were killed after 3 and 6 months. The mucous membrane and bone tissue were analysed for concentrations of Co, Cr, Ni, Mo, Al, and Ti by atomic absorption spectrophometry and a radiochemical neutron activation technique. With the exception of Ti, higher concentrations of all the above elements were found in the tissue near the implants when compared with contralateral controls. However, no signs of corrosion, macroscopic or microscopic, were observed on the surface of the implants.

The effects of maternal caffeine intake during pregnancy on mineral contents of fetal rat bone

Various levels of maternal caffeine ingestion during pregnancy were investigated to determine whether caffeine will affect the mineral contents of the growing bones of fetal rats. On day 8 of gestation, rat dams were fed with a 20% protein diet supplemented with 0.5 mg, 1 mg, or 2 mg caffeine/100 g of dams body weight as an experimental group and the same without caffeine as a control until day 22 of gestation. Fetuses were removed by cesarean section on day 22 and mandibular bones were removed to study the mineral contents of calcium, phosphorus, magnesium, and zinc. Although the mandible weighed more in the 0.5-mg caffeine group as compared to the controls, an additional increase of caffeine resulted in a decrease in weight. All calcium, magnesium, and zinc contents per bone decreased in the 1- and 2-mg caffeine groups as compared to either controls or 0.5-mg caffeine group, whereas phosphorus stayed relatively constant regardless of the different levels of caffeine intake. When data are expressed as per gram of bone tissue, most of the mineral contents among the groups disappeared suggesting that normal growth and development of the fetal bone are impaired as a results of maternal caffeine intake. Caffeine intake during gestation in the present study indicates that different levels of caffeine intake may exert not only different effects on mineral contents in bone development, but also affect the growth of the fetal bone.

Stratigraphic context of fossil hominids from the Omo group deposits: northern Turkana Basin, Kenya and Ethiopia

The chronometric framework developed for Plio-Pleistocene deposits of the northern Turkana Basin is reviewed in light of recent advances in lithostratigraphy, geochemical correlation, paleomagnetic stratigraphy, and isotopic dating. The sequence is tightly controlled by 20 precise ages on volcanic materials. These ages are internally consistent but are at variance with estimates for the boundaries of the magnetic polarity time scale by about 0.07 my. This discrepancy can be only partially resolved at present. Based on the established chronometric framework and stratigraphic sequences, depositional ages can be estimated for significant marker beds. These ages can in turn be used to constrain the 449 hominid specimens thus far reported from the basin. Ages for most hominid specimens can be estimated with a precision of +/- 0.05 my. In addition, the chronometric framework will be applicable to other paleontological collections, archeological excavations, and future discoveries in the basin.

Mandibular fluoride concentration and its relation to age in roe deer (Capreolus capreolus L.)

1. Mandibular fluoride content was recorded in 63 roe deer (33 males, 30 females) between 9 months and 10 years of age, taken from an area in SW Germany not exposed to increased fluoride deposition. 2. Bone fluoride level was positively correlated with age (t-test, P less than or equal to 0.001), the increase in concentration being higher in younger animals and declining in older deer. 3. In the sample studied, no significant sex specific difference in mean mandibular fluoride concentration was found (t-test, P greater than 0.05).

A histochemical localization on Maclura pomifera lectin during osteogenesis

Mandibular condyles of 4-week-old Wistar strain rats and mandibles of ICR strain mice from 14 days gestation stage to 2 days postnatal stage were used to investigate the localization of Maclura pomifera lectin (MPA) during two modes of osteogenesis. During endochondral ossification of the mandibular condyle, MPA was only localized at the peripheral regions of calcified cartilage after the destruction of chondrocyte lacunae. Bone extracellular matrix (ECM) was not reacted with MPA. In intramembranous ossification of mice mandibles, MPA was stained intensively in the early bone ECM. The intensity of the MPA reaction decreased during bone development. In both cases of osteogenesis, chondroclasts and osteoclasts showed the strong affinity to MPA. These results indicated that the time- and position-specific changes within ECM proceeded during osteogenesis and that MPA was the useful probe to detect chondroclasts and osteoclasts.

Bone mineral content of mandibles: normal reference values--rate of age-related bone loss

The purpose was to obtain the normal sex- and age-related reference values for the bone mineral content (BMC) in the bones of the mandible and the forearms, as estimated by dual-photon absorptiometry; to examine the effect of tooth loss on the mandibular BMC, i.e., BMC in the basal part of the mandible; and to analyze the rate of the sex- and age-related BMC loss in the mandible in normal old edentulous individuals greater than or equal to 70 years of age and its relationship to the corresponding BMC loss in the forearm bones. The following groups were measured: young dentate adults (n = 100; women (W): men (M) = 1:1), young, long-term edentulous W (n =15), and old edentulous individuals (n = 24 W, 10 M). In the old group the BMC measurements were repeated after 2- or 3-year period (n = 18 W, 10 M). The analyses indicate that the mandibular BMC reference values differ by sex and age; but correction for the state of dentition seems of minimal benefit. The average BMC loss (%) in the bones of the mandible and the forearms seems to be higher in old W (1.5 and 1.4% per year) than in old M (0.9 and 0.7% per year), but of the same magnitude in each sex. The relationship between the BMC loss (%) in the two sites was significant (P less than 0.01) but rather weak. Thus, it seems important to follow the sex- and age-related BMC loss in the mandible separately.

Calcitonin gene-related peptide-immunoreactive nerve fibers in mandibular periosteum of rat: evidence for primary afferent origin

Peptidergic neurons may play a role in the local regulation of bone mineralization. The neuropeptide vasoactive intestinal peptide (VIP) increases bone resorption in vitro, while calcitonin gene-related peptide (CGRP) has been shown to inhibit bone resorption in vitro. We have previously reported that sympathetic nerves with VIP-immunoreactivity innervate bone and periosteum. In the present study we sought to determine if CGRP fibers, like VIP fibers, exist in periosteum and what their origin might be. In whole-mount preparations of mandibular periosteum from rat, CGRP- and VIP-immunoreactive (IR) nerve fibers were present as networks within the periosteum. In preparations using two-color immunofluorescence, most CGRP-IR fibers were also immunoreactive for substance P (SP). In rats in which the subperiosteal space subjacent to the mandibular molars was injected with Fast blue or Fluoro-gold, retrogradely labeled cells were seen in ipsilateral trigeminal ganglia, superior cervical ganglia, and nodose ganglia. Individual cells labeled with both CGRP immunoreactivity and retrograde tracer were seen only in the mandibular portion of the trigeminal ganglion. These data suggest that CGRP-IR nerve fibers in periosteum may be of primary afferent origin. Given the reported effects of CGRP on bone mineralization, the present results suggest that primary afferent nerves containing CGRP and SP, as well as sympathetic nerves containing VIP, may play a role in focal bone remodeling.

Prenatal protein-energy malnutrition alters various biochemical components of the membranous bones in fetal rats

The effects of prenatal protein-energy malnutrition on the biochemical parameters of the membranous bone were studied using fetal rats. Timed pregnant rats were fed a protein-deficient diet as an experimental group from day 13 of gestation, whereas control dams were fed a normal protein diet. By day 15, radioactive Na2SO4 was injected. On day 22, all fetuses were delivered by cesarean section. The hexosamine content per milligram dry tissue, and the protein and hexosamine contents per guanidine-HCl extract were greater in the mandibles but less in the calvaria of the malnourished group than in those of the controls. Calcium content per gram dry tissue was lower in both bones of the malnourished group. 35S-sulfate uptake per milligram dry tissue or milligram proteoglycan was greater in the malnourished group than in the controls in both bones. The mandible in the malnourished group had less lower-weight molecular proteoglycan subunits in the dissociative condition. Protein-energy malnutrition affects the mandible and calvaria in different ways, although both bones originate from membranous bone. Insufficient degradation of proteoglycan could be the reason for the delay of mineralization in the malnourished bones.

A comparative immunocytochemical study on the subcellular distributions of 44 kDa bone phosphoprotein and bone gamma-carboxyglutamic acid (Gla)-containing protein in osteoblasts

Bone gamma-carboxyglutamic acid (Gla)-containing protein (BGP or osteocalcin) and 44 kDa bone phosphoprotein (44K BPP, also called Sialoprotein I or osteopontin) have been localized at the ultrastructural level in osteoblasts from woven bones of newborn rats. Frozen, undecalcified sections of periodate-lysine-paraformaldehyde fixed specimens were incubated with affinity purified, monospecific antibodies against BGP or 44K BPP. The sites of the antigen-antibody reaction were demonstrated by the avidin-biotin-peroxidase complex method using the Hanker-Yates reagent as a peroxidase substrate. In some cases immunostaining could only be achieved after detergent treatment. The immunostained sections were then flat-embedded in Epon 812 and processed for electron microscopy. Strong specific intracellular labeling was obtained with both antibodies, but the patterns of staining differed significantly: BGP antigenicity was mainly located in the endoplasmic reticulum (ER), whereas 44K BPP behaved as a Golgi-specific antigen. In both cases, however, we found no evidence for immunostained secretory vesicles. There was no correlation between the expression of BGP by osteoblasts and the morphological aspect of these cells, their apparent degree of polarization with respect to the bone matrix, or their relation with the mineralized phase.

Maternal low-carbohydrate high-protein diet affects mandibular growth in diabetic newborn rats

Dams with 7 pups each were randomly assigned to two different diets. Twelve dams were fed a normal (20%) protein diet and were divided into two groups of 4 and 8 animals. Pups from group 1 (n = 28) were injected with citrate buffer as a control. Pups from group 2 (n = 56) were injected with streptozotocin. Twelve additional dams were fed a 40% protein diet. They were also divided into two groups of 4 and 8 animals. Pups from group 3 (n = 28) were injected with citrate buffer as a control. Pups from group 4 (n = 56) were injected with streptozotocin. Forty-eight hours later, diabetic status was determined using Dextrostix. On Day 15, pups were injected with [14C]proline to determine collagen synthesis and 45Ca to study mineralization. After the pups were killed, blood glucose levels were determined. Then mandibles were removed. Milk from each dam was also collected after injection of oxytocin. At the time of killing, blood glucose levels in diabetic pups were less than earlier levels, though still higher than those of controls on either diet. The weights of body and mandible, collagen contents, and the total calcium contents in the diabetic group were in general less than those of the nondiabetic group on the 20 and 40% protein diets. 45Ca uptake in the diabetic group was significantly increased compared with those of the nondiabetic rats on both diets. The percentage reduction in the mandibles of diabetic rats from those of nondiabetic rats on the 40% protein diets was consistently less than that of animals on the 20% protein diets. The higher protein contents of the maternal milk in the 40% protein group may partly be responsible for the smaller impairment of mandibular development in the diabetic over nondiabetic animals. It is concluded that maternal low-carbohydrate high-protein diets will play indirectly a beneficial role in the development of the mandibles of diabetic newborns.

Concentration of cefuroxime in the bones of albino white rats: a comparative study of femur, humerus, and mandible

The levels of cefuroxime in rat bones with a different morphology, function, blood supply, and proportion between lamellar and cancellous bone were studied, after a 24-h administration of 750mg/kg X 3. The concentrations in the right and left femora, humeri, and mandibles of the same animal were measured 2 h after the last administration. The result indicate statistically significant differences between femur and humerus (P less than 0.001), femur and mandible (P less than 0.05), and humerus and mandible (P less than 0.05).

The changes in quality of mandibular bone mineral in otherwise totally immobilized rhesus monkeys

The status of bone mineral and osteocalcin in the young adult Rhesus monkey mandible was assessed following a 14-day period of postcranial immobilization, and after 7- and 28-day recovery periods. Specimens of cortical bone taken from the compact bone at the inferior border of the jaws were ground in liquid nitrogen and sieved to a particular size below 20 micron. The bone powder was then fractionated in a bromoform-toluene density gradient to determine its mineralization profile (Ca, P, CO3, and osteocalcin), and X-ray diffraction was used to determine apatite crystal size in some fractions. There was no change in the chemistry of the mandibular bone from the immobilized animals. However, the mineralization profile in that group showed a significant shift toward the higher density fractions, indicating the presence of a greater than normal content of mature well-mineralized bone. While this trend was accentuated in the jaws following a 7-day postimmobilization recovery period, partial recovery of the normal profile was observed after a 28-day recovery period. The osteocalcin profile shifted like the mineralization profile during the immobilization and recovery periods. X-ray diffraction analyses showed that the shift in the mineralization profile during the immobilization period was associated with a decrease in apatite crystal size.

Plasminogen activators in alveolar bone in man

Plasminogen activators in alveolar bone in man was studied in quenching experiments by a fibrin slide technique with addition of monospecific antibodies against tissue plasminogen activators (t-PA) and urokinase (u-PA). The plasminogen activator activity was quenched in the slides with anti-t-PA. No quenching was observed in the slides with anti-u-PA. This does not exclude the possibility that enzymatically inactive pre-urokinase is present.

Ampicillin concentrations in human serum, gingiva, mandibular bone, dental follicle, and dental pulp following a single oral administration of bacampicillin

Ninety-six patients who underwent the extraction of impacted mandibular third molars in a nonfasting state were given a single oral dose of bacampicillin preoperatively. Specimens of serum from venous blood (n = 107), gingiva (n = 57), mandibular bone (n = 68), dental follicle (n = 56), and dental pulp (n = 43) were obtained during the operation and assayed for ampicillin content. The mean peak concentrations in serum, gingiva, mandibular bone, dental follicle, and dental pulp all occurred approximately 90 minutes after administration. The concentration ratios of the tissues to the corresponding serum at the peak time were 0.50, 0.20, 0.34, and 0.61, respectively. Bacampicillin showed good absorption by the intestine, and sufficient concentrations of the resulting metabolite, ampicillin, were found in the oral tissues.

Morphometry of orthopantomographic mandibular bone changes during radiation therapy

It is generally considered that mineral loss in the bone must amount to 30 per cent or more before any changes become visible to the naked eye in conventional radiography of the skeleton. Early changes in the mandibular bone during radiation therapy are therefore difficult to detect. Abnormalities of the bone caused by irradiation are vascular and cellular in nature. Morphometry detects the changes earlier than conventional radiography. Nineteen patients with a malignant process in the oral cavity or the naso- or hypopharynx but with no evidence of metastases in the mandibular periosteum or bone marrow were given radiation therapy. They were investigated using morphometry together with orthopantomography. The investigation demonstrated a decrease in the number of trabeculae and an increase in the amount of marrow space and compact bone during irradiation. Thus it is possible to detect early radiographic changes by morphometry, but this method is more laborious than scintigraphy. The abnormalities of the mandibular bone were reversible, which signifies the recovery of bone after irradiation with therapeutic doses.

Ampicillin concentrations in human serum, gingiva, mandibular bone, dental follicle, and dental pulp following a single oral dose of talampicillin

Eighty-one patients who underwent the extraction of impacted mandibular third molars in the nonfasting state were given a single oral dose of talampicillin (500 mg) preoperatively. Specimens of venous blood (n = 132), gingiva (n = 70), mandibular bone (n = 78), dental follicle (n = 63), and dental pulp (n = 59) were obtained during the operation and assayed for ampicillin content. The mean peak concentrations in serum (9.64 micrograms/ml), gingiva (4.72 micrograms/mg), mandibular bone (1.77 micrograms/ml), dental follicle (3.46 micrograms/ml), and dental pulp (5.53 micrograms/mg) all occurred at approximately 150 minutes after administration of talampicillin. The ratios of the corresponding serum concentration to the peak concentrations in the various oral tissues when both were plotted as drug concentration curves were: gingiva, 0.50; mandibular bone, 0.16; dental follicle, 0.34; and dental pulp, 0.52. Talampicillin was absorbed well by the intestine, and sufficient concentrations of the resulting metabolite, ampicillin, were found in oral tissues.

Dual-photon absorptiometry of mandibles: in vitro test of a new method

A new method for non-invasive in vivo measurement of changes in bone mineral content (BMC) of mandibles, comprising two-dimensional dual-photon absorptiometry (GT45), has been developed and tested in vitro on mandibular specimens. The analysis showed that: 1) in vitro precision and accuracy of the methods are high, 2) effect of fat and soft tissue on photon attenuation is slight when scanning jaws and forearm bones, 3) BMC in units (U/cm2) in standard area, comprising mandibular base and body in left molar region, is representative for BMC in total mandibular base and body, 4) cortical bone constitutes the main part of measured BMC in mandibles, and 5) BMC of molar region is highly correlated to cortical bone mass in mm3/mm2 subperiosteal surface of standard locality anterior to and below mental foramen, measured by histomorphometry. GT45 seems suitable for in vivo estimation of BMC changes in edentulous jaws and in mandibular base and body of dentate mandibles in longitudinal and cross-sectional studies. The radiation dose is negligible.

In vivo measurement of bone mineral content of mandibles by dual-photon absorptiometry

The purpose of this study was 1) to reveal the short- and long-term precision of noninvasive in vivo measurements of bone mineral content (BMC) in larger and smaller parts of mandibles and in forearm bones by a new two-dimensional dual-photon attenuation system GT45; 2) to develop normal reference values and ranges for mandibular BMC in individuals between 20-40 yr of age without known systemic diseases and with normal oral state, (n = 56, F:M = 1:1), and 3) to relate mandibular BMC with forearm bone BMC, sex and age, by comparing BMC values of a well-defined normal old test group (n = 24, F:M = 1:1, 70-81 yr of age) with the normal reference values. The analyses indicated: 1) the in vivo short- and long-term precision of the methods is high. 2) BMC of mandibles and forearm bones is significantly related to sex and age (P less than 0.01, and in mandibles of young females/males: P = 0.02). 3) BMC in mandibles and forearm bones is significantly correlated in both age groups (P less than 0.01) with relatively weak coefficients of correlation. GT45 may be used to follow BMC changes in mandibles in groups or single individuals after surgical treatment and to evaluate sex and age dependent BMC changes in mandibles and forearm bones.

Age-related changes in the content of non-reducible crosslinks in rat mandibular bone

Age-related changes in the content of non-reducible crosslink amino acids, pyridinoline and histidinoalanine, in rat mandibular bone were studied. The pyridinoline content markedly increased up to 12 months of age and thereafter slightly increased. The histidinoalanine content was low until 3 months of age, but thereafter increased significantly up to 24 months. Total collagen content remained constant throughout the experiment. From these results, pyridinoline and histidinoalanine may serve as markers for the maturation and senescence, respectively, of mandibular bone.

Identification of collagen type I and type II in chondroid tissue

This paper deals with investigations concerning the matrix of chondroid tissue. Among the 73 human fetus or child mandibles and the 42 cat mandibles we have studied histologically and microradiographically, 8 human and 3 cat mandibles were used to determine the collagen composition in chondroid tissue matrix, and 10 cat mandibles were analyzed in order to have an ultrastructural approach to chondroid tissue. Both in human and cat mandibles, types I and II collagen were identified by indirect immunofluorescence and immunoperoxidase techniques. Electron microscopic analysis shows large collagen fibrils which correspond to type I collagen, and smaller collagen fibrils, principally located at the periphery of the chondroid cells. From our investigations, chondroid tissue should be considered as being different from both bone and cartilage, although it is not a transitional tissue, since no transformation of chondroid tissue into bone is observed; it should be classified as an intermediate tissue between cartilage and bone because of its morphological characteristics.

[Nuclear spin tomographic study of the facial skeleton. I. Nuclear spin and computed tomographic anatomy]

The resolution of NMR and CT was compared using axial sections of the normal anatomic structures of the facial skeleton. It was shown that NMR was superior in differentiating muscles, tonsils, mucosa, lymph nodes and blood vessels. The demonstration of bone and its differentiation from air-containing spaces is often difficult. Metallic, non-ferromagnetic dental fillings, which cause serious artefacts on CT, do not affect NMR.

[The mineral phase of Malherbe's calcifying tumor]

The mineral phase of a calcified tumour of Malherbe (pilomatrixoma) was studied using microradiography, chemical analysis and X-ray diffraction. It was compared with the mineral phase of a piece of human mandibular bone from a matched subject with respect to age and sex. The main part of the mineral phase of the pilomatrixoma belonged to the biological apatite system; an additional whitlockite phase was found. In the homogeneous areas of the tumour, the radioopacity was similar to that of bone.

Simulating certain aspects of hypogravity: effects on bone maturation in the non-weight bearing skeleton

This study reports the effects of simulation of certain aspects of hypogravity (via partial skeletal unloading) on the growth and maturation of the non-weight bearing mandibles of 41-d and 1-yr-old rats. Partial skeletal unloading was effected by elevating the hindquarters (PULEH), and this simulation was controlled with normally loaded animals fed either ad libitum or the average amount of food consumed by the the experimental group (group-mean fed). The chemical status of the mandibles after 10 d or 14 d PULEH closely resembled that of control rats. The younger PULEH rats and their group-mean fed controls demonstrated a trend toward impaired maturation of mineral and matrix moieties; yet the concentrations of calcium (Ca) and phosphorus (P) expressed as a ratio to collagen hydroxyproline content were normally distributed within a density gradient profile which separates the mineral and matrix moieties into various age-dependent fractions. These data demonstrate that 10 d or 14 d PULEH in young or old rats, respectively, is not sufficient to elicit the maturation deficit observed in the mandibles of rats flown for 18.5 d in the Soviet Biosatellite Cosmos-1129. Unless the duration of PULEH is critical, the cephalad fluid shift which is common to PULEH and spaceflight animals cannot be solely responsible for the flight-induced maturation deficit. Because the mandibles of the PULEH rats remain antigravity-postured, the results emphasize the importance of gravity unloading to the impairment of mandibular bone matrix/mineral maturation during spaceflight. Decreased gravity and, hence, gravity unloading cannot be mimicked in ground-based models of hypokinesia.

Concentrations of cloxacillin, dicloxacillin and flucloxacillin in dental alveolar serum and mandibular bone

Deep infections caused by staphylococci are serious complications after oral surgery. Intensive antibiotic treatment is always necessary in these infections. Isoxazolylpenicillins are often used. Levels of three isoxazolylpenicillins, namely, cloxacillin, dicloxacillin and flucloxacillin, were measured in serum, dental alveolar serum and mandibular bone in 60 patients undergoing surgical removal of impacted third molars after a single dose of 500 mg. The systemic serum concentrations were higher than the dental alveolar serum concentrations in most patients. The maximum concentration in the alveolar serum was 3.8-6.4 microgram/ml for cloxacillin, 6.0-15.0 microgram/ml for dicloxacillin and 10.0-15.0 microgram/ml for flucloxacillin. The concentration in mandibular bone was 2.0 +/- 0.4 microgram/g for cloxacillin, 2.0 +/- 0.5 microgram/g for dicloxacillin and 2.0 +/- 0.5 microgram/g for flucloxacillin.

ESR on the hydroxyl ion vacancies in the apatites

Heating biological apatites and synthetic apatites in the stream of inert gas saturated with heavy water vapor, introduces OD ions which substitute for the hydroxyl (OH) ions and partially for the OH vacancies, depending on the heating time and the gas flow rate. This has been verified by ESR and partially by IR. Deuteration gives no serious alterations of the a-axis dimension or of the PO4 bands in the IR spectra. These findings have been interpreted as suggesting that the OH ions diffuse out and the OD ions diffuse in through specific pathways, and the diffusing ions interact permanently with none of the other ions in the apatite structure. Heating in dry inert gas results in the formation of hydroxyl ion vacancies. The ESR spectra of these samples in the g = 2.06 region have been interpreted in terms of O-2 and O-. The shortening of the a-axis dimension in this case has been accounted for based on the loss of structurally incorporated H2O and the loss of the OH ions on the hexad axis.

EMG, bite force, and elongation of the masseter muscle under isometric voluntary contractions and variations of vertical dimension

The relation EMG activity, bite force, and muscular elongation was studied in eight subjects with complete natural dentition during isometric contractions of the masseter muscle, measured from 7 mm to almost maximum jaw opening. EMG was registered with superficial electrodes and bite force with a gnathodynamometer. In series 1, recordings of EMG activity maintaining bite force constant (10 and 20 kg) show that EMG is high when the bite opening is 7 mm, decreases from 15 to 20 mm, and then increases again as jaw opening approaches maximum opening. In series 2, recordings of bite force maintaining EMG constant show that bite force increases up to a certain range of jaw opening (around 15 to 20 mm) and then decreases as we approach maximum jaw opening. Results show that there is for each experimental subject a physiologically optimum muscular elongation of major efficiency where the masseter develops highest muscular force with least EMG activity.

Concentrations of cephalexin in mandibular alveolar bone, blood, and oral fluids

Results from this study of 16 patients who underwent extractions and alveoloplasty indicate that cephalexin effectively penetrates alveolar bone. After cephalexin had been administered, 500 mg four times a day for 48 hours, the average concentration in bone exceeded the average minimal inhibitory concentration of six organisms commonly encountered in infections and bacteremias of dental origin. These data and the current knowledge of cephalexin suggest that cephalosporins may have a unique use in dental infections or potentially harmful bacteremias caused by susceptible organisms.

Skeletal concentrations of lead in ancient Peruvians

The level of biologic lead (expressed as the ratio of atomic lead to atomic calcium) in bones of Peruvians buried 1600 years ago was found to be 3 x 10(-8), as compared to 2100 to 3500 x 10(-8) in the bones of present-day residents of England and the United States. The ratio of barium to calcium was 2 to 3 x 10(-6) in bones of ancient Peruvians and present-day Americans. Barium and lead have similar morphologic distributions in organisms, so this discrepancy for lead must result from overexposure of present-day people to industrial lead and not from natural variations. The magnitude of this discrepancy has been confirmed by two different lines of investigation not reported in this article. This new evidence suggests that natural interactions of lead in human cells have not yet been determined because reagents, nutrients and controls used in laboratory and field studies have been contaminated with lead far in excess of naturally occurring levels.

Metallic contamination of bone during drilling procedures

The influence of drills and burs of different shapes and materials on the amount of metallic transfer was studied. In these experiments, holes were drilled in bone with radioactive tools and the amount of metal transferred to the bone was measured by means of gamma-ray spectrometry. The proportion of the drill material transferred to the bone varied widely, depending on the type of the drill, its previous usage, and on the specific element considered. Most of the drills transfer a few microgram of iron to the bone, together with smaller quantities of cobalt, tungsten, and chromium. The total quantity of material transferred to the bone from new drills exceeded that of old drills. Almost invariably, the second drilling transferred less material than did the first, even with used drills.