Genetic predisposition to external apical root resorption in orthodontic patients: linkage of chromosome-18 marker.

External apical root resorption (EARR) is a common orthodontic treatment sequela. Previous studies implicate a substantial genetic component for EARR. Using a candidate gene approach, we investigated possible linkage of EARR associated with orthodontic treatment with the TNSALP, TNFalpha, and TNFRSF11A gene loci. The sample was comprised of 38 American Caucasian families with a total of 79 siblings who completed comprehensive orthodontic treatment. EARR was assessed by means of pre- and post-treatment radiographs. Buccal swab cells were collected for extraction and analysis of DNA. No evidence of linkage was found with EARR and the TNFalpha and TNSALP genes. Non-parametric sibling pair linkage analysis identified evidence of linkage (LOD = 2.5; p = 0.02) of EARR affecting the maxillary central incisor with the microsatellite marker D18S64 (tightly linked to TNFRSF11A). This indicates that the TNFRSF11A locus, or another tightly linked gene, is associated with EARR.

Planned cesarean hysterectomy: A preferred alternative to separate operations.

OBJECTIVE: The aim of this study was to evaluate our institutional experience with planned cesarean hysterectomy. STUDY DESIGN: In this retrospective case-control investigation of a 16-year experience, 100 pregnant women who underwent planned cesarean hysterectomy were compared with 37 patients who underwent cesarean delivery followed by a hysterectomy performed within 6 months. RESULTS: Women undergoing planned cesarean hysterectomy did not have any demonstrable increase in intraoperative or postoperative complications when compared with the cesarean delivery plus later hysterectomy group. Primarily as a result of significantly reduced hospital stay and shorter total operative time, there was a significant financial advantage associated with a single planned cesarean hysterectomy with respect to separate operations. CONCLUSIONS: A policy to undertake planned cesarean hysterectomy for carefully selected patients appeared to produce advantages without increasing risks for these patients. Secondarily, it provided resident physicians the opportunity to learn the operation with supervision and under controlled circumstances.

The impact of leiomyomas on pregnancy.

In this retrospective case control investigation, 51 pregnant patients who were diagnosed by ultrasound with uterine myomas were compared to 102 randomly selected control patients to determine if the ultrasound diagnosis of one or more leiomyoma is associated with increased untoward pregnancy outcomes compared to controls. Women with uterine myomas were older (p = 0.001), more likely to be African American (p = 0.001), and undergo Caesarean delivery (p = 0.03) than controls. However, when women who underwent abdominal delivery for previous myomectomy (n = 5) were excluded from analysis, there was no significant difference in the incidence of Caesarean delivery. Overall, there was no difference in the incidence of obstetric complications between groups even when the data was stratified for large and/or multiple leiomyomas. The discovery of uterine leiomyomas by gestational ultrasound does not appear to place the patient at increased risk for preterm labour, early delivery, or other untoward pregnancy outcomes.

Changes in patient screening for a clinical study of dental implants after increased awareness of tobacco use as a risk factor.

Independent external monitoring committees are an important part of scientific clinical trials. They monitor patient safety, study progress, investigators' performance, and accurate interpretation/reporting of the study data. Data trends observed by a study monitoring committee detected a change in the pattern of patient screening by investigators after an increased awareness that tobacco use could directly compromise the osseointegration of root-form dental implants. This increased awareness is believed to have altered the number of active smokers accepted into a multicenter prospective dental implant study. Recent data analyses indicate that the success ratios were improved by alterations in this discretionary inclusion-exclusion criterion.

Angiogenesis and osteogenesis in an orthopedically expanded suture.

The purpose of this study was to examine the angiogenic and the subsequent osteogenic responses during a 96-hour time-course after sutural expansion. Fifty rats were divided into: (1) a control group that received only angiogenic induction through injection of 5 ng/gm recombinant human endothelial cell growth factor (rhECGF); (2) an experimental group that received orthopedic expansion and rhECGF; (3) a sham group that received expansion and sodium chloride (NaCl) injection; and (4) a baseline group that received no expansion or injection. All rats were injected with 3H-thymidine (1.0 microCi/gm) 1 hour before death to label the DNA of S-phase cells. Demineralized sections (4 microm thick) were stained with hematoxylin and eosin. Angiogenesis and cell migration were analyzed with a previously established cell kinetics model. Analysis of variance was used to test the hypothesis that enhancement of angiogenesis stimulates reestablishment of osteogenic capability. Blood vessel number, area, and endothelial cell-labeled index significantly increased in experimental groups, but no difference was found between control and baseline groups. Labeled-pericyte index and activated pericyte numbers in the experimental group were also higher than in the sham groups. These results show that supplemental rhECGF enhances angiogenesis in expanded sutures but not in nonexpanded sutures. Data also suggest that pericytes are the source of osteoblasts in an orthopedically expanded suture.

Angiogenic induction and cell migration in an orthopaedically expanded maxillary suture in the rat.

The purpose was to examine the effect of an angiogenic factor on cell migration patterns and osteoblast histogenesis during the 96 h following orthopaedic expansion of the anterior maxillary suture. Fifty rats were divided into four groups: (1) a control group that received only angiogenic induction via injection of 5 ng/g body wt recombinant human endothelial-cell growth factor; (2) an experimental group that received orthopaedic expansion and angiogenic induction; (3) a sham group that received orthopaedic expansion and normal saline injection; and (4) a baseline group that received no expansion or injection. The experimental and sham groups were subdivided to conduct experiments over 1, 2, 3 or 4 days. The anterior portion of each maxilla was dissected free and demineralized. Sections (4 microns thick) were cut from every block and stained with Mayer's haematoxylin and eosin. Cell migration was analysed using a previously established cell-kinetics model. The osteoprogenitor cells were divided into four categories according to nuclear volume: A cells (40-79 microns3), B cells (80-119 microns3), C cells (120-169 microns3) and D cells (> or = 169 microns3 A' cells are the portion of the A cell population that responds to osteogenic stimulus. As previously defined in periodontal ligament, the reciprocal association of a decreasing number of less differentiated (A + A) cells and an increasing number of C + D cells, as a function of distance from the nearest major blood vessel, was consistently found in all groups. This suggests a vascularly oriented gradient of progressively more differentiated osteoprogenitor cells. Also, A + A' cells were predominately located within 20 microns of the nearest major blood vessel whereas the C + D cells were found at a distance > 30 microns from the nearest major blood vessel. These results suggest that the A'-->C shift occurs 20-30 microns from the nearest major blood vessel. In the angiogenic induction groups, the numbers of committed osteoprogenitors (A + A') were significantly higher than in the sham group at day 1. At day 3, the numbers of preosteoblasts (C + D) in angiogenic sutures were significantly higher than in the sham groups. This enhancement of preosteoblast population strongly suggests the possible role of activated pericytes in expanded sutures as a source of osteoprogenitor cells.

Autoimmune diseases in pregnancy.

Autoimmune diseases are a significant problem in women of reproductive age. This article reviews some of the more common autoimmune disorders and discusses their diagnosis and management during pregnancy. The effects of the autoimmune disorder on pregnancy and the effects of pregnancy on the course of the autoimmune disorder are also discussed with an emphasis on the implications for clinical management.

Detection of intra-amniotic infection by gas-liquid chromatography.

The use of gas-liquid chromatography to detect short-chain organic acids in the amniotic fluid of patients with amnionitis has been previously described. Most of the studies describe patients in the early third trimester with such infections. The purpose of the current study was to confirm the correlation of infection with increased production of organic acids and to assess the effect of gestational age on the presence of these short-chain fatty acids in the amniotic fluid. Six patients with confirmed chorioamnionitis were used as positive control subjects. Seventy-two patients at various gestational ages from 18 to 42 weeks with negative Gram's stain and culture results from the amniotic fluid were used as negative control subjects. The data revealed an increased production of organic acids, particularly pyruvic, oxalic and succinic, in patients with amnionitis regardless of gestational age. Interestingly, patients with noninfected amniotic fluid also revealed an increase in the concentrations of volatile organic acids between 27 and 32 weeks' gestation. It appears from this study that previous results correlating chorioamnionitis with an increased production of organic acids in the amniotic fluid may have been confounded by gestational age.

Bone physiology and metabolism in dental implantology: risk factors for osteoporosis and other metabolic bone diseases.

Placing a dental implant elicits a time-dependent bone response controlled by wound-healing factors (cytokines, bioelectrical signals), biomechanics (gravitational, functional, and therapeutic loads), and mineral metabolism (hormones, diet, excretion). The osseous response to an implant involves four physiological stages: (1) endosteal and periosteal callus formation; (2) compaction and remodeling of the callus; (3) remodeling (turnover) of the nonvital interface and adjacent bone; and (4) maturation (secondary mineralization) of new bone. Long-term maintenance of a rigid implant interface is related to continual bone remodeling. Common metabolic bone disorders affecting potential implant patients are osteopenia ("osteoporosis"), renal osteodystrophy, osteomalacia, and Paget's disease. The most prevalent problem is a long-term negative calcium balance leading to a compromise in bone strength. Symptomatic osteoporosis (usually wrist, hip, and/or spine fractures) affects 4 to 50 percent of the population depending on age, race, sex, endocrine status, and life-style. Postmenopausal white and Asian females present the greatest risk. The jaws of "osteoporotic" adults are variably affected because of the moderating influence of mechanical function. Management of metabolic bone disorders is an important consideration in diagnosis, treatment planning, and long-term monitoring of dental implants. Bone metabolic counseling, a natural extension of preventative dentistry, is an unexpected benefit readily appreciated by patients and their families.

Histologic evaluation of the bone/graft interface after mandibular augmentation with hydroxylapatite/purified fibrillar collagen composite implants.

Samples of the bone/graft interface were evaluated histologically in five patients 1 year after mandibular ridge augmentation with a composite of hydroxylapatite particles in a matrix of purified fibrillar collagen (HA/PFC). The resulting defects were refilled with HA/PFC after the biopsy specimens were obtained. Histologic examination of the specimens yielded no evidence of purified fibrillar collagen. Hydroxylapatite particles were surrounded by dense fibrous host connective tissue, trabeculae of woven and lamellar bone, or both. HA/PFC was found to be biocompatible with human tissue and receptive to direct bone apposition on the hydroxylapatite particles.

A comparative study of temporomandibular symptoms following mandibular advancement by bilateral sagittal split osteotomies: rigid versus nonrigid fixation.

Rigid fixation to attach proximal and distal segments during bony healing of osteotomy sites has become increasingly popular. The effects of rigid fixation on the temporomandibular joints have been questioned. The purpose of this study was to evaluate the effects of rigid fixation after bilateral sagittal split osteotomies on temporomandibular dysfunction symptoms. Forty patients who had mandibular advancement surgery were evaluated for temporomandibular joint dysfunction. Twenty had received rigid fixation, and twenty had received nonrigid fixation. It was determined that there was no statistically significant difference in temporomandibular signs or symptoms between patients who were treated with rigid internal fixation for bilateral sagittal split osteotomies for mandibular advancement and those patients who were treated with nonrigid wire fixation.

The incidence of preterm labor and specific risk factors.

A retrospective review of patients at high risk for preterm delivery because of twin gestation, uterine malformation, incompetent cervix, or previous preterm delivery was carried out to assess the rates of preterm labor and spontaneous preterm birth. Among the 119 patients with multifetal gestation, 46% had preterm labor and 36% delivered before 37 weeks' gestation. In the 58 patients with an anomalous uterus, the rate of preterm labor was 19%, and 14% had early deliveries. Of those with incompetent cervices (115), one-fourth had preterm labor and 17% had an early birth. When a history of one or more preterm deliveries was present, the preterm labor rate ranged from 41-68%, with an early delivery rate of 30-47%. Prophylactic tocolytic therapy did not prolong gestations significantly. Maternal smoking did not have an adverse effect on the incidence of preterm labor except in twin pregnancies, for which early delivery was more likely. The percentages for preterm delivery are slightly lower than those found in the literature; this may be attributable to improvement in preterm birth prevention efforts including patient education, more frequent examinations, home uterine activity monitoring, and daily nursing contact.

Comparative sensitivity of sea urchin sperm bioassays to metals and pesticides.

A simple sperm/fertilization bioassay, primarily using sea urchin gametes, has been developed and used by a variety of laboratories. This assay was recently refined into a standard test and is now being used by the U.S. Environmental Protection Agency and others for toxicity testing in marine waters. One factor that has lagged behind the development of this assay is the comparison of its sensitivity to various common toxicants as compared to other bioassay systems and life stages of other marine organisms. The objective of this study was to compare the sensitivity of a standardized sea urchin sperm/fertilization assay to the responses of embryo, larval, and adult marine organisms to metals (Ag, Cd, Cu, Pb, Zn) and pesticides (DDT, Dieldrin, Endrin, Endosulfan) added to natural seawater. The results, although highly variable, generally showed that sperm/fertilization and embryo assays were quite sensitive to the metals tested, but that the larval and adult assays were more sensitive to the pesticides. These comparative data, together with other studies of complex effluents, show that the standardized sperm/fertilization bioassay is an especially quick and useful tool for biomonitoring of marine waters.

Osseous adaptation to continuous loading of rigid endosseous implants.

Titanium implants, with an acid-etched surface, were screwed into holes 3 mm in diameter, about 1 cm apart, carefully prepared with an internally irrigated, surgical bur in the femurs of 3- to 6-month-old rabbits. During the first 3 days after surgery, fluorescent bone labels revealed extensive bone formation, particularly at the endosteal margin of the surgical defect, indicating preservation of a high degree of osteogenic capacity. A lattice of coarse, woven bone began encapsulating the implant within 3 days. By the end of 6 weeks, mature, lamellar bone filled voids at or near the implant surface and a rigid bone/implant interface was routinely achieved. Nonspecific, subperiosteal bony hypertrophy was noted within 6 weeks after implants were placed in young, growing animals (3 months old), but not in adults (6 months old). After 6 to 12 weeks of healing, a 100-gm load was applied for 4 to 8 weeks by stretching a stainless steel spring between the implants. All but one of twenty loaded implants remained rigid. Immediate loading of four pairs of implants resulted in spontaneous spiral-type ("torsional") fractures of the femur within 1 week. These results indicate that (1) relatively simple and inexpensive titanium implants develop a rigid osseous interface, (2) 6 weeks is an adequate healing period, prior to loading, to attain rigid stability and avoid spontaneous fracture, (3) continuously loaded implants remain stable within the bone, (4) bone formation is observed on periosteal surfaces subjected to concave flexure (compression), (5) cancellous-type bone orients perpendicularly between loaded implants, apparently corresponding to lines of stress, (6) new secondary osteons are propagated at or near the surface of loaded implants, (7) the remodeling (turnover) cycle for rabbit compact bone is about 6 weeks, and (8) endosseous implants have potential as a source of firm osseous anchorage for orthodontics and dentofacial orthopedics.

Cell population dynamics of periodontal ligament stimulated with parathyroid extract.

Young adult rats were injected with parathyroid extract (PTE). Periodontal ligament (PDL) adjacent to a previously resorbing alveolar bone surface was divided into four zones number I to IV, from bone to cementum. Zones I and IV were within 25 mmu of the bone and cementum surfaces, respectively, while a line bisecting the center of the PDL separated Zones II and III. A net increase of about 16 total nuclei in all zones was observed during the first five hours after PTE administration. Since local mitosis accounted for no more than two nuclei, approximately 14 cells apparently migrated into the area. Over the first five hours Zones I and II combined showed a 21-cell increase, being apparently the sole recipients of cells migrating into the field (14) plus approximately seven more from Zone III, which lost cells during the time period. The concurrent histological observation in Zone II, of increased intravascular monocytes and perivascular macrophages during the first five hours, suggests cells are migrating into Zone II via vascular channels. The data suggest two sources for increased PDL cellularity associated with stimulated osteoclast histogenesis: (1) local PDL cellular proliferation and (2) influx of migrating cells (probably through vascular channels) during first five hours after PTE.