Profile of the dentist in the oral healthcare team in countries with developed economies.

This paper confines itself to the description of the profile of a general dentist while outlining where the boundary between specialist and generalist may lie. The profile must reflect the need to recognize that oral health is part of general health. The epidemiological trends and disease variation of a country should inform the profile of the dentist. A particular tension between the provision of oral healthcare in publicly funded and private services may result in dentists practicing dentistry in different ways. However, the curriculum should equip the practitioner for either scenario. A dentist should work to standards appropriate to the needs of the individual and the population within the country's legal and ethical framework. He/she should have communication skills appropriate to ascertain the patient's beliefs and values. A dentist should work within the principles of equity and diversity and have the knowledge and clinical competence for independent general practice, including knowledge of health promotion and prevention. He/she should participate in life-long learning, which should result in a reflective practitioner whose clinical skills reflect the current evidence base, scientific breakthroughs and needs of their patients. Within the 4-5 years of a dental degree it is not possible for a student to achieve proficiency in all areas of dentistry. He/she needs to have the ability to know their own limitations and to access appropriate specialist advice for their patients while taking responsibility for the oral healthcare they provide. The dentist has the role of leader of the oral health team and, in this capacity; he/she is responsible for diagnosis, treatment planning and the quality control of the oral treatment. The dental student on graduation must therefore understand the principles and techniques which enable the dentist to act in this role. He/she should have the abilities to communicate, delegate and collaborate both within the dental team and with other health professionals, to the benefit of the patient. The profile of a dentist should encompass the points raised but will also be based upon competency lists which are published by a variety of countries and organizations. It is important that these lists are dynamic so that they are able to change in light of new evidence and technologies.

Interactions between plant hormones regulate submergence-induced shoot elongation in the flooding-tolerant dicot Rumex palustris.

Rumex palustris has the capacity to respond to complete submergence with hyponastic (upward) growth and stimulated elongation of petioles. These adaptive responses allow survival of this plant in habitats with sustained high water levels by re-establishing contact with the aerial environment. Accumulated ethylene in submerged petioles interacts with ethylene receptor proteins and operates as a reliable sensor for the under-water environment. Further downstream in the transduction pathway, a fast and substantial decrease of the endogenous abscisic acid concentration and a certain threshold level of endogenous auxin and gibberellin are required for hyponastic growth and petiole elongation. Interactions of these plant hormones results in a significant increase of the in vitro cell wall extensibility in submerged petioles. Furthermore, the pattern of transcript accumulation of a R. palustris alpha-expansin gene correlated with the pattern of petiole elongation upon submergence.

The effect of frog pressure and downward vertical load on hoof wall weight-bearing and third phalanx displacement in the horse--an in vitro study.

A shoe was designed to combine the advantages of a reverse shoe and an adjustable heart bar shoe in the treatment of chronic laminitis. This reverse even frog pressure (REFP) shoe applies pressure uniformly over a large area of the frog solar surface. Pressure is applied vertically upward parallel to the solar surface of the frog and can be increased or decreased as required. Five clinically healthy horses were humanely euthanased and their dismembered forelimbs used in an in vitro study. Frog pressure was measured by strain gauges applied to the ground surface of the carrying tab portion of the shoe. A linear variable distance transducer (LVDT) was inserted into a hole drilled in the dorsal hoof wall. The LVDT measured movement of the third phalanx (P3) in a dorsopalmar plane relative to the dorsal hoof wall. The vertical component of hoof wall compression was measured by means of unidirectional strain gauges attached to the toe, quarter and heel of the medial hoof wall of each specimen. The entire limb was mounted vertically in a tensile testing machine and submitted to vertical downward compressive forces of 0 to 2,500 N at a rate of 5 cm/minute. The effects of increasing frog pressure on hoof wall weight-bearing and third phalanx movement within the hoof were determined. Each specimen was tested with the shoe under the following conditions: zero frog pressure; frog pressure used to treat clinical cases of chronic laminitis (7 N-cm); frog pressure clinically painful to the horse as determined prior to euthanasia; frog pressure just alleviating this pain. The specimens were also tested after shoe removal. Total weight-bearing on the hoof wall at zero frog pressure was used as the basis for comparison. Pain-causing and pain-alleviating frog pressures decreased total weight-bearing on the hoof wall (P < 0.05). Frog pressure of 7 N-cm had no statistically significant effect on hoof wall weight-bearing although there was a trend for it to decrease as load increased. Before loading, the pain-causing and pain-alleviating frog pressures resulted in a palmar movement of P3 relative to the dorsal hoof wall compared to the position of P3 at zero frog pressure (P < 0.05). This difference remained statistically significant up to 1300 N load. At higher loads, the position of P3 did not differ significantly for the different frog pressures applied. It is concluded that increased frogpressure using the REFP shoe decreases total hoof wall weight-bearing and causes palmar movement of P3 at low weight-bearing loads. Without a shoe the toe and quarter hoof wall compression remained more constant and less in magnitude, than with a shoe.

Recombinant human bone morphogenetic protein-7 in maxillary sinus floor elevation surgery in 3 patients compared to autogenous bone grafts. A clinical pilot study.

BACKGROUND/AIMS: This pilot study was designed to determine the clinical bone formation ability of a human recombinant DNA bone morphogenetic protein-7, also referred to as Osteogenic Protein-1 [OP-1] combined with a collagen carrier, implanted in the maxillary sinus of 3 patients. The results were compared with a group of 3 patients treated with sinus floor elevation and autogenous bone grafts. METHODS: 6 consecutive patients, 4 female and 2 male, between 48 and 57 years of age were treated by means of sinus floor elevation for insufficient bone height in the posterior maxilla for implant surgery. 3 patients, 2 female and 1 male, were treated with OP-1 attached to a collagen device. In these patients, 4 maxillary sinus grafting procedures according to Tatum's method were carried out. 1 g of collagen carrier containing 2.5 mg rhOP-1 mixed with 3 ml of saline was placed between the bony floor and the elevated mucosal lining of the most caudal part of the maxillary sinus, in order to increase the vertical bone dimension to place dental implants of a sufficient length. The 3 other patients, also 2 female and 1 male, with a total of 5 sinus sites, were treated with sinus floor elevation and autogenous iliac crest bone grafts. After 6 months, during dental implant preparation, bone cores were taken for histology. Thus, clinical, radiological and histological results of the 2 groups of 3 patients were compared. RESULTS: 6 months after sinus grafting with OP-1, in 1 male, well-vascularized bone-like tissue of good quality was observed clinically. This could be confirmed by histology. In the second, female, patient no bone formation was observed at all. A cyst-like granular tissue mass, without purulent content, was removed. In the 3rd, female, patient, who received bilateral sinus grafts, some bone-like formation was seen, however it showed flexible tissue which led to the decision that at 6 months after the sinus grafting, the implant placement had to be postponed. In all 5 autogenous grafted sinuses a bone appearance similar to normal maxillary bone was observed clinically as well as histologically and dental implants could be placed six months after sinus floor elevation surgery. CONCLUSIONS: These findings indicate that the OP-1 device has the potential for initiating bone formation in the human maxillary sinus within 6 months after a sinus floor elevation operation. However, the various findings in these 3 patients indicate that the behaviour of the material is at this moment insufficiently predictable, in this indication area. Further investigation is indicated before OP-1 can be successfully used instead of the "gold standard" autogenous bone graft.

Relationship between juvenile bruxing and craniomandibular dysfunction.

A longitudinal study was conducted over 5 years to investigate the relationship between juvenile bruxing and craniomandibular disorders. A total of 150 bruxers between the ages of 6 and 9 years were examined for oral parafunctions and TMJ symptoms. Of these, 126 were re-examined for the same signs and symptoms after 5 years. The results showed that only 17 individuals had retained their bruxing habit. In common with other studies, we found that symptoms reduced with age. It was concluded that juvenile bruxing was a self-limiting condition which does not progress to adult bruxism and which appeared to be unrelated to TMJ symptoms.

A clinical evaluation of a novel toothbrush design.

A new toothbrush design, the Snakebrush, was clinically evaluated along with the Flexible and Precision brushes. In this parallel, random-allocation investigation, the plaque removing qualities of the 3 brushes were evaluated over a period of 30 days. 60 patients of good dental health between the ages of 20 and 30 years formed the basis of the clinical trial. Mean plaque area scores were evaluated and recorded after a 1-min brush at baseline, day 15 and day 30. Gingivitis indices and bleeding on probing indices were also recorded at the same time intervals. Both uni- and multivariate analyses of our data suggested that the Snakebrush removed significantly more plaque than the 2 controls. For both lingual and buccal surfaces, subjects who had used the Snakebrush showed a significant decline in bleeding on probing and qinqivitis indices.

Predictors of exercise capacity and adaptability to training in patients with coronary artery disease.

PURPOSE: Systolic left ventricular dysfunction is a weak predictor of exercise tolerance in patients with chronic congestive heart failure. This study aimed to determine physiologic and other predictors of effort tolerance and adaptability to training in a wide variety of patients with coronary artery disease. METHODS: One hundred seventy-one patients (group 0) with documented coronary artery disease and various degrees of left ventricular dysfunction were enrolled into a medically supervised exercise training program for 6 months. One hundred six patients had an ejection fraction greater than 50% (group 1), 38 patients between 35% and 50% (group 2), and 27 patients less than 35% (group 3). RESULTS: Resting parameters of systolic and diastolic left ventricular function did not predict the effort tolerance of patients with coronary artery disease at any level of left ventricular impairment. Noncardiac factors including age, gender, Broca index, and forced vital capacity explained 50% of the variation in peak oxygen uptake in group 0. Peak oxygen uptake, ventilatory threshold, and treadmill time to exhaustion increased significantly after training in all groups. The magnitude of the improvement in these variables was the same for all groups. CONCLUSIONS: Noncardiac factors were better predictors of the effort tolerance of patients with coronary artery disease than parameters of left ventricular function at entry to an exercise program or after 6 months of training. A similar degree of adaptation to training was seen in all patients regardless of their degree of left ventricular systolic or diastolic dysfunction.

Dental asymmetry, maternal obesity, and smoking.

This study examines the levels of fluctuating dental asymmetry in four samples of school children: those whose mothers were obese and had smoked during the pregnancy concerned (n = 111); those whose mothers were obese non-smokers (n = 114); those whose mothers were non-obese smokers (n = 104); and those whose mothers were lean non-smokers (n = 111). The degree of fluctuating asymmetry was assessed by means of a rescaled asymmetry measure. Obesity was defined as Quetelet's index in excess of 30, and smoking status as at least 20 cigarettes per day during the pregnancy concerned. When the magnitudes of fluctuating asymmetry in children of lean smokers were compared to the control group of lean non-smokers, no significant univariate differences were found. Children of obese mothers, whether these smoked or not, were found to have significantly raised levels of asymmetry. An analysis of variance confirmed that the combination of obesity and maternal smoking was a significant predictor of fluctuating dental asymmetry. The teeth involved tended to be the maxillary first incisor and molars. It is concluded that maternal obesity has a destabilizing effect on the developing fetus and that this effect appears to be enhanced in obese mothers who smoked. This effect was absent in lean mothers, irrespective of their smoking status.

Nucleolar organizer regions (AgNORs) in odontogenic cysts and ameloblastomas.

The aim of this study was to determine whether nucleolar organizer regions (AgNORs) may be of value in distinguishing various odontogenic cysts from the unicystic ameloblastoma. Histological sections were prepared from fifteen cases each of odontogenic keratocyst, residual cyst, dentigerous cyst, unicystic ameloblastoma and conventional ameloblastoma. In each case intra-nuclear AgNOR dots were counted in 100 consecutive basal nuclei. Statistical comparison of the least squares means showed that those areas of unicystic ameloblastomas lined by characteristic epithelium had a significantly lower AgNOR count than the other groups (P < 0.05). The dentigerous cysts had significantly higher AgNOR counts than the residual cysts and unicystic ameloblastomas (P < 0.05). These differences may or may not be indicative of variations in metabolic, proliferative or transcriptional activity. We conclude that AgNOR counts are not of diagnostic significance and cannot be used to distinguish the various odontogenic cysts from one another nor from the unicystic ameloblastoma.

RNA phage KU1 has an insertion of 18 nucleotides in the start codon of its lysis gene.

We have determined the nucleotide sequence of group II RNA phage KU1. The most conspicuous difference in the comparison with other group II members such as GA and JP34 is the presence of an insertion in the start codon of the lysis gene. In GA and JP34, the coat and lysis genes overlap by one nucleotide in the configuration UAAUG. The 18-nt insertion in KU1 is positioned between the A and the U of the start codon. It does not affect the coat reading frame, but it destroys the AUG start codon and separates the previously overlapping genes by 17 nts. The insert creates a UUG codon at its 3' border which serves as the start site for lysis protein synthesis in KU1. We also show that analogous to the group I phages, such as MS2 and fr, expression of the lysis gene in KU1 and JP34 is coupled to termination of translation at the coat gene. RNA secondary structure models for the central parts of KU1 and JP34 are suggested which can account for the insertion as a separate stem-loop structure.

Delayed tooth formation in children exposed to tobacco smoke.

Panoramic radiographs of 203 Caucasoid children between the ages of seven and ten years were examined for an evaluation of dental development. Four groups were studied: a control group in which neither parent had smoked during the pregnancy concerned, a group exposed to tobacco smoke from the mother only, a group exposed to smoke from the father only, and finally a group exposed to tobacco smoke from both parents. In each case, the dental age (determined according to the method of Moorrees) was contrasted to the chronological age of the subject. Overall results showed that there were no differences in dental ages related to gender. Maximum differences between chronological and dental ages were found in children subjected to cigarette smoke from both parents. Here, a 35% reduction in dental maturation was noted. Most affected teeth were the maxillary second premolars, while the central incisors were the least affected.

Determinants of blood pressure in Sowetan infants.

A study of the effect of different variables on the blood pressure of Sowetan infants was undertaken with the Birth-to-Ten (BTT) cohort as the study population. Variables studied at 1 year included anthropometric indices, aspects of feeding practices and relationship to maternal blood pressure. Systolic blood pressure was recorded in 792 infants at 1 year; 29,3% of the variance was determined by weight, upper arm circumference, age at which formula feeds were started, length and volume of formula feeds (in order of significance). Amount of salt added to diet approached statistical significance. Data available for 353 of the 752 infants showed a correlation between the infants' and the mothers' blood pressure. The maternal blood pressure only accounted for an additional 2% of the variance; approximately 70% of blood pressure variance is therefore still unexplained. Firm recommendations with regard to use of formula feeds and the addition of salt to infants' diet are difficult to make on the basis of this limited follow-up.

Inequalities in the pattern of dental delivery in South Africa.

The pattern of dental delivery of three groups of private general practitioners were evaluated. The first group consisted of dentists who charged fees based on the National Schedule of the Dental Association of South Africa, the second charged fees at the recommended Scale of Benefit and served an urban population, while the last group served township dwellers at the Scale of Benefits. In each case, sequential claims of 500 medical scheme members were evaluated for ten randomly selected dentists within each group. Uni- and multivariate analyses revealed significant differences between these groups which centred on the use of cast restorations, bleaching of vital teeth and treatment of diseases of the oral mucosa. Because these differences do not conform to documented differences in dental needs between the two groups, it is concluded that other non-clinical factors influence the delivery of private dentistry.

Microclimatic effect on vertical migration of Haemonchus contortus and Haemonchus placei third-stage larvae on irrigated Kikuyu pasture.

The influence of microclimate on numbers of third-state larvae of haemonchus contortus and Haemonchus placei in four strata of irrigated Kikuyu pasture was assessed. On 36 different, interspersed days three replicates of pasture samples were collected on three occasions per day from 1990-1992 for larval recovery and the log10 mean counts of the larvae recovered were analysed by use of ANOVA models. Because the ground-surface area from which herbage was collected was standardized, estimated larval counts for the different strata could be compared; this was not possible in our previous studies. For H. contortus, the estimated larval counts in the four strata were predicted by microclimatic air temperature, relative humidity and soil moisture, with the coefficient-of-determination (R2) values ranging from 0.15-0.35. Of these, air temperature had the greatest effect. The same three predictors, together with illumination and wind speed, featured for H. placei, with R2 values of 0.19-0.52. With the exception of wind speed and illumination, which (for H. placei) had the opposite effect, all the microclimatic parameters listed, predicted an increase in numbers of larvae from a lower to an upper strata.

Translational control of maturation-protein synthesis in phage MS2: a role for the kinetics of RNA folding?

The gene for the maturation (A) protein of the single-stranded RNA coliphage MS2 is preceded by an untranslated leader of 130 nt. Secondary structure of the leader was deduced by phylogenetic comparison and by probing with enzymes and chemicals. The RNA folds into a cloverleaf, i.e., three stem-loop structures enclosed by a long-distance interaction (LDI). This LDI is essential for translational control. Its 3'moiety contains the Shine-Dalgarno region of the A-protein gene, whereas its complement is located 80 nt upstream, i.e., about 30 nt from the 5'-terminus of the RNA chain. Mutational analysis shows that this base pairing represses expression of the A-protein gene. We present a model in which translational starts can only take place on nonequilibrated RNA, in which base pairing between the complementary regions has not yet taken place. We suggest that this pairing is kinetically delayed by the intervening sequence, which contains the three hairpins of the cloverleaf. The model is mainly based on the observation that reducing the length of the intervening sequence reduces expression, whereas increasing the length has the opposite effect. In addition, further stabilization of the LDI by a stronger base pair does not lead to a decrease in A-protein synthesis. Such a decrease is predicted to occur if translation would be controlled by the equilibrium structure of the leader RNA. These and other observations fit a kinetic model of translational control by RNA folding.

Effects of prenatal exposure to tobacco smoke on developmental stability in children.

The effects of maternal and paternal smoking on fetal and neonatal dental development were investigated in a sample of 199 school children. Fluctuating asymmetry was evaluated in the maxillary arcades of four groups of children: those whose mothers had smoked, those whose fathers had smoked, those whose parents both had smoked, and finally, those whose parents had not smoked. When the magnitudes of fluctuating asymmetry in children exposed to parental tobacco smoke from one parent only were compared with the control group, no general univariate differences were found. Children exposed to smoke from both parents, however, showed significantly elevated levels of asymmetry in four out of six comparisons. In contrast, an analysis of variance failed to find significant differences on the basis of sex, parity, smoking status, or their interactions. It is concluded that parental smoking does not result in developmental destabilization of the fetus and neonate.