Identification and control of an outbreak of ciprofloxacin-susceptible EMRSA-15 on a neonatal unit

We report the identification and control of an outbreak of a ciprofloxacin-susceptible strain of UK epidemic meticillin-resistant Staphylococcus aureus (EMRSA)-15 on a neonatal unit (NNU). All babies were screened for MRSA on admission using ciprofloxacin-containing media which did not detect the outbreak strain. The first identified case was a premature baby who developed MRSA bacteraemia with associated tibial osteomyelitis and multiple subcutaneous abscesses. The outbreak strain was subsequently identified in the nasopharyngeal secretions of a second child who was not clinically infected. Screening of all patients on the NNU using non-ciprofloxacin-media identified two other colonised babies. All four patient isolates were EMRSA-15, spa type t022, SCCmec IV, Panton-Valentine leucocidin (PVL) negative, indistinguishable by pulsed-field gel electrophoresis and susceptible to all non-beta-lactam antimicrobials tested. The outbreak strain was cultured from four of 48 environmental sites in a communal milk-expressing room. Unsupervised movement of mothers to and from the milk-expressing room may have contributed to the outbreak. Control measures included cohort isolation of affected babies, improved environmental cleaning, increased emphasis on hand hygiene and education of mothers. Ciprofloxacin-containing media should be used with caution for MRSA screening in settings where ciprofloxacin-susceptible strains (including community-associated MRSA) are increasing in prevalence.

Intrauterine T-cell activation and increased proinflammatory cytokine concentrations in preterm infants with cerebral lesions

Brain injury is common in very preterm infants, and intrauterine infection is a frequent antecedent of preterm birth. We examined the relation of cerebral damage to intrauterine antigen exposure and inflammation in 50 infants who were born at 23-29 weeks' gestation. Higher concentrations of cytokines (tumour necrosis factor alpha [TNF-alpha], and interleukins [IL], 1beta, 6, and 10) and CD45RO(+) T lymphocytes in umbilical blood predicted cerebral lesions detected by magnetic resonance imaging very soon after delivery. Our results suggest that infants who mount an immune response in utero are at higher risk of cerebral lesions.

Comparison of the validity of periodontal probing measurements in smokers and non-smokers

AIM

To determine whether the reduced inflammation and bleeding and increased fibrosis reported in tobacco smokers affect the validity of clinical probing measurements by altering probe tip penetration.

METHOD

A constant force probe was used to measure probing depths and sound bone levels at six sites on 64 molar teeth (384 sites) in 20 smoking and 20 non-smoking patients from grooves made with a bur at the gingival margin prior to extraction. Connective tissue attachment levels were measured from the grooves with a dissecting microscope following extraction. Data were analysed using robust regression with sites clustered within subjects.

RESULTS

Sites in smokers showed more calculus but less bleeding than sites in non-smokers (p<0.05). The mean clinical probing depth was not significantly different (smokers: 5.54 mm, confidence intervals=4.81 to 6.28; non-smokers: 6.05 mm, ci=5.38 to 6.72). The corresponding post-extraction pocket depth measurements (smokers: 4.95 mm, ci=4.30 to 5.61; non-smokers: 5.23 mm, ci=4.49 to 5.96) were less than clinical probing depth in sites from both smokers and non-smokers (p<0.01). However, the proportional difference was less in smokers (p<0.05), particularly in deeper pockets, indicating that clinical probe tip penetration of tissue was greater in non-smokers. Regression analysis indicated that the presence of calculus and bleeding also influenced the difference in clinical probe penetration (p<0.05).

CONCLUSION

Clinical probing depth at molar sites exaggerates pocket depth, but the probe tip may be closer to the actual attachment level in smokers due to less penetration of tissue. This may be partly explained by the reduced inflammation and width of supra-bony connective tissue in smokers. These findings have clinical relevance to the successful management of periodontal patients who smoke.

Thrombopoietin in the fetus and neonate

C-mpl ligand or thrombopoietin (Tpo) is increasingly recognised as the major regulator of platelet homeostasis in humans. Relatively little is known about Tpo in the fetus and neonate but no evidence has yet been found to suggest any fundamental difference in Tpo structure, function and regulation in the fetus and neonate compared to older age groups. Tpo mRNA transcripts have been detected in the fetus as early as 6 weeks post conception and the liver appears to be the main site of Tpo production in both the fetus and neonate. The vast majority of healthy newborns have detectable levels of circulating Tpo and raised Tpo levels are commonly, but not consistently, found in thrombocytopenic neonates. In adults receptor binding and subsequent metabolism of Tpo is proposed as the main method of regulation of the circulating Tpo level. Preliminary studies in neonates showing increased Tpo levels most often during thrombocytopenia accompanied by reduced megakaryocytopoiesis supports this concept. In addition to this demonstrable fetal and neonatal endogenous Tpo production megakaryocyte progenitor and precursor cells from the fetus and from preterm and term newborns proliferate and differentiate extensively in-vitro in response to exogenous Tpo. Furthermore a recent study has shown a marked rise in platelet count in newborn rhesus monkeys administered one form of recombinant Tpo. Although these studies remain at an early stage together these findings strongly suggest that, as in adults, Tpo is the major regulator of platelet homeostasis in the fetus and neonate. Thrombocytopenia is common in sick neonates and progress in understanding this important clinical problem is likely to be greatly enhanced by the current and future research into Tpo production, function and regulation in the healthy and thrombocytopenic fetus and neonate.

Thrombopoietin has a primary role in the regulation of platelet production in preterm babies

Thrombocytopenia in the first days of life, in association with evidence of reduced megakaryocytopoiesis and platelet production at birth, is common in sick preterm babies. Thrombopoietin (Tpo) is the major regulator of platelet production in adults. However, these babies have low Tpo levels at birth, suggesting that the Tpo response to thrombocytopenia may be impaired. To test this hypothesis we 1) measured Tpo levels, 2) measured circulating megakaryocyte progenitors serially over the first 12 d of life in 13 preterm babies with early onset thrombocytopenia and in 14 control babies with evidence of normal megakaryocytopoiesis, and 3) measured Tpo levels in thrombocytopenic children (n = 13). In control babies, platelet counts and progenitor numbers remained normal and Tpo levels were consistently low-d 1:160+/-23 pg/mL (mean+/-SEM), d 4/5: 154+/-18 pg/mL and d 12: 150+/-58 pg/mL. In thrombocytopenic babies, platelet counts and megakaryocyte progenitor numbers were significantly lower than controls at d 1: platelets 130+/-14 x 10(9)/L versus 255+/-20 x 10(9)/L (p < 0.001) and megakaryocyte progenitors 552 versus 3907 colonies/mL (mean, p < 0.001), and fell further to nadir on d 4/5: platelets 76+/-6 X 10(9)/L versus 259+/-21 x 10(9)/L (p < 0.001) and MK progenitors 479 versus 2742 colonies/mL (p < 0.05). Tpo levels were only slightly raised on d 1:247+/-52 pg/mL (p = 0.24), but then rose sharply by d 4/5: 425+/-75 pg/mL (p < 0.001). By d 12, platelet count, megakaryocyte progenitors and Tpo level (145+/-29 pg/mL) had returned to control levels. Tpo levels at platelet nadir in thrombocytopenic babies were significantly lower than in thrombocytopenic children: mean 425 versus 1383 pg/mL (p < 0.001). These data show that Tpo is important in platelet homeostasis in preterm babies, with a close reciprocal relationship with platelet count and progenitor numbers during thrombocytopenia. However, the increase in Tpo levels seen in these babies was modest, despite significantly impaired megakaryocytopoiesis, and when compared with that seen in children with thrombocytopenia. This offers further evidence that preterm babies have an impaired Tpo response to thrombocytopenia and suggests that recombinant human Tpo may have a role in the prevention/treatment of preterm thrombocytopenia.

The relationship of health beliefs and psychological mood to patient adherence to oral hygiene behaviour

Patient adherence to oral hygiene instructions (compliance) is important for the success of periodontal treatment. However, there are many different definitions and measures of what constitute patient adherence. Also, many different models of patient behaviour have been studied, with inconsistent or conflicting findings. The purpose of this study was to explore the relationships between health beliefs (three aspects of dental health locus of control, health values and adherence intent), psychological mood and periodontal outcomes. Complete periodontal data were obtained for 47 untreated patients prior to instruction in oral hygiene, and again 4-6 weeks later. Psychological variables were measured by questionnaire and adherence was measured by reductions in clinical variables (plaque and inflammation). Data were analysed using an item analysis of the questionnaire to assess the internal consistency of the subscales. The results showed overall stability in the psychological variables and reductions in the clinical variables. The main result was a series of negative associations between plaque scores and adherence intent. Inflammatory variables showed some association with psychological constructs related to dependence on external factors.

Endogenous thrombopoietin levels and effect of recombinant human thrombopoietin on megakaryocyte precursors in term and preterm babies

Thrombocytopenia (platelets <150 x 10[9]/L) is common in the early newborn period. Recent evidence suggests this is due mainly to impaired fetal megakaryocytopoiesis/platelet production. The cause remains unknown. Thrombopoietin (Tpo) is now recognized as the major regulator of platelet production in adults. However, nothing is known about Tpo levels, or the role of Tpo in megakaryocytopoiesis/platelet production, in the fetus/newborn. To answer these questions we: 1) measured plasma Tpo levels by ELISA at birth in healthy term (n = 17) and preterm (gestational age, 24-34 wk) babies (n = 16), and in thrombocytopenic preterm babies (n = 13); and 2) assessed the in vitro Tpo dose response characteristics of circulating megakaryocyte precursor cells (MKp) from all three groups. The median Tpo levels were similar in term babies 145 pg/mL (range 52-237 pg/mL) compared with preterm babies 132 pg/mL (32-318 pg/mL). In the thrombocytopenic preterm babies the median Tpo level of 185 (46-264) was not significantly higher than in healthy babies, despite the fact that their median platelet counts were significantly lower--82 x 10(9)/L (range 21-135), compared with the healthy preterm babies 252 x 109/L (152-320)--p < 0.0001. Tpo levels in the thrombocytopenic preterm babies were also much lower than levels measured in three thrombocytopenic children (905, 2138, and 2700 pg/mL). MKp from all three groups showed dose-dependent proliferation in response to Tpo (p < 0.01 at 100 ng/mL Tpo). Increases in MKp were greater in healthy and thrombocytopenic preterm babies when compared with term babies: 48.2-, 24.6-, and 9.8-fold, respectively (p < 0.05 for both comparisons). These results strongly suggest that: 1) Tpo is a major regulator of megakaryocytopoiesis/platelet production in the fetus/newborn, 2) impaired fetal Tpo production may be a factor in early thrombocytopenia in preterm babies, and 3) recombinant human Tpo is likely to be effective in the treatment of early neonatal thrombocytopenia.

A randomized controlled trial of a 2% minocycline gel as an adjunct to non-surgical periodontal treatment, using a design with multiple matching criteria

Topical locally delivered minocycline is an adjunctive to non-surgical periodontal treatment, but there are few reported trials. Previous trials have reported differences between changes in probing depth in treatment and control groups, but no differences in probing attachment level. In the present study, 30 subjects were paired according to gender, age, ethnic group, smoking habits, and probing depths. Both groups received intensive oral hygiene education and root planing with local anaesthesia. Active or placebo gel was placed subgingivally at planed sites in each subject according to a double-blind protocol, immediately after instrumentation, and 2 and 4 weeks later. A periodontal examination was made with a constant force probe before instrumentation, and 6 and 12 weeks later, 2 subjects failed to complete the study, and their pairs were therefore not included in the analysis. Results were tested with analysis of covariance. Differences between groups in mean probing depth did not reach statistical significance at any visit (baseline: test (T) = 5.93 mm, control (C) = 5.74 mm; 6 weeks: T = 3.53 mm, C = 3.63 mm; 12 weeks: T = 3.29 mm, C = 3.44 mm), but mean probing attachment levels were different (p < 0.05) at both reassessments (baseline: T = 6.86 mm, C = 6.83 mm; 6 weeks: T = 4.93 mm, C = 5.30 mm; 12 weeks T = 4.91 mm, C = 5.27 mm). There was also a difference in the number of sites with bleeding on deep probing at 12 weeks (p < 0.05). This trial showed that adjunctive minocycline gel provided a more advantageous outcome for nonsurgical periodontal treatment in terms of probing attachment level and bleeding on deep probing. This trial was a good example of experimental, as opposed to community, design, and used limited resources to show a clear result.

A study of personality factors and interaction in 4th-year dental students and their teachers

No previous investigation has considered dental student and teaching staff opinions on their relationship with each other. In a day when students are increasingly asked for feedback on the quality of teaching by staff, such investigations are of particular interest. This exploratory study was designed to compare the personality characteristics of a clinical year of dental students with those of the teaching staff they most frequently encountered, and to investigate these factors for possible associations with the quality of perceived teaching-learning interaction between the 2 groups. A complete 4th year of dental students (n = 87), and those teachers whom they met regularly (n = 80), were asked to participate. Subjects completed a form of the Myers-Briggs personality questionnaire simplified for use in education, and were asked to assess their relationship with persons in the other group. All the students and 75% of the staff, after follow-up, returned usable data. There was close similarity between staff and student personality profiles, and perception of working relationships by both groups was largely independent of personality factors and temperament. There were differences in staff perception of their relationship with extrovert and introvert students. Students showed minor differences in their perception of staff relationships with respect to two other personality factors. These findings indicate a substantial similarity between staff and students, and suggest a mature and stable relationship between people in the 2 groups.

Laryngeal and diaphragmatic activities with a single expiratory load in newborn lambs

Expiratory resistive loads elicit compensatory reflexes in the neonate which regulate end-expiratory lung volume (EEV). This study investigated the coordination of laryngeal and diaphragmatic activities when awake neonatal lambs were exposed to a single breath expiratory resistive load. The lambs were chronically instrumented for recording trans-upper airway pressure and electromyographic signals from the posterior cricoarytenoid, thyroarytenoid, and diaphragm. The lambs breathed through a sealed face mask connected to a pneumotachograph and non-rebreathing valve with a loading manifold connected to the expiratory port. Single breath expiratory loads produced, decreased airflow; prolongations of PCA EMG activity and diaphragm EMG inhibition; decreased trans-upper airway resistance and increased EEV. In the post-load breath, inspiratory volume decreased, expired volume increased, and EEV returned towards control baseline. Thus, neonatal lambs compensate for a single breath expiratory load by dilating the larynx and prolonging expiratory time. In the post-load breath, integrated activities of laryngeal and diaphragmatic muscles, coupled with mechanical factors return EEV towards baseline.

A double-blind trial of tetracycline in the management of early onset periodontitis

The aim of the study was to evaluate the adjunctive effect of systemic tetracycline (250 mg qds for 14 days) in sequential root planing and surgical phases of treatment in a randomised, double-blind controlled trial. 38 patients who were under 26 years of age, in good general health and with localised (15 test/15 control) or generalised (4 test/4 control) early onset periodontitis completed the non-surgical phase. Data were analysed by ANOVA using baseline covariates and transformations where appropriate. Improvements in probing depth, probing attachment level and bleeding on probing were significantly better in the group treated with adjunctive tetracycline, at 3 months post-treatment. 26 patients (13 test/13 control) subsequently completed the surgical phase (modified Widman flap surgery with adjunctive tetracycline or placebo as before) and were re-examined at 6 months and 12 months. In the test group, 58% of the originally affected teeth required surgery compared to 75% in the control group. Surgery produced further reductions in mean probing depths but no further gains in probing attachment. There were no further statistically significant differences between test and control groups for any of the clinical measures, although the tetracycline group appeared to maintain an advantage. In conclusion, systemically administered tetracycline is a useful adjunct in the management of early onset periodontitis, particularly in non-surgical treatment.

An investigation of the validity of attachment level measurements with an automated periodontal probe

There is a need for information on the validity of probing depth and attachment level measurements made with automated probes. In this study, 34 teeth in 9 patients were measured with the Florida probe from points marked with a bur prior to extraction. After extraction, connective tissue attachment levels were measured from the same points with a dissecting microscope. Mean measurements of attachment level were similar with probing (5.13 +/- 2.08 mm) and laboratory (5.18 +/- 2.26 mm) assessments. The correlation between these measurements was 0.72 (p < 0.001), and a t-test of the paired measurements showed no difference (t = 0.44; p = 0.66). The Florida probe thus showed satisfactory validity for this group of measurements of advanced periodontitis. However, there was substantial lack of agreement between individual probing measurements and the validity criterion of laboratory attachment level measurements, and the intra-class correlation coefficient was 0.46. It was concluded that the Florida probe was suitable for studies in which measurements were averaged, but not for longitudinal study of individual sites.

Initial study of periodontal status in non-insulin-dependent diabetics in Mauritius

OBJECTIVES

Investigation of Mauritian non-insulin diabetic periodontal health.

METHODS

In Port Louis, the capital of Mauritius, 24 patients with non-insulin-dependent diabetes mellitus were matched by age with 24 controls. Because matching was incomplete for gender and race, the groups were treated as independent for data analysis. Operator-blind scores were recorded for the presence of plaque, bleeding on probing, probing depth, recession and probing attachment level.

RESULTS

When variations in plaque and age were taken into account, there was a significant difference in probing attachment level between the groups (diabetic mean = 4.16 mm, control mean = 3.09 mm), and an effect of gender on gingival bleeding which may relate to tobacco smoking.

CONCLUSION

In an isolated community with a 13% prevalence of NIDDM, this study confirms previous periodontal findings regarding the effect of the disease.

Periodontal inflammation and attachment loss: a critical problem for biological studies

BACKGROUND

In biological studies of periodontitis, there has been long-standing confusion between the ubiquitous phenomena of inflammation and the essential criterion of attachment loss. This is partly attributable to inadequate methods of clinical measurement, but seems also to be a consequence of an unproven and usually unstated assumption that the same biological processes underlie both inflammation and attachment loss. Developments in unidimensional clinical probing methods have helped in studies of periodontal treatment. However, such methods are intrinsically unsuitable in studies of periodontal diseases, and may have given them a false sense of security. the confusion has been compounded by inappropriate use of statistical techniques in an attempt to solve problems which do not arise from mathematical models but are intrinsic to measurement methods.

OBJECTIVE

This paper is a clinician's attempt to state the current difficulties and suggest some ways forward, including the development of three-dimensional measurement, non-invasive probing, and several objectives for biochemical, microbiological and immunological research.

Single-blind studies of the effects of improved periodontal health on metabolic control in type 1 diabetes mellitus

Uncontrolled studies have suggested a beneficial effect of periodontal treatment on metabolic control of insulin-dependent diabetes mellitus (IDDM). We therefore conducted controlled single-blind studies, using current metabolic status indicators in IDDM subjects free of significant complications other than periodontal diseases. In the 1st study, 41 IDDM subjects with gingivitis and early periodontitis were randomly assigned to treatment (oral hygiene and scaling) or control groups. The study was completed by 16 experimental and 15 control subjects. Reassessment after 2 months showed a Hawthorne effect in the control group, and no difference between groups. However, further analysis showed a relationship between individual metabolic control variation and gingival inflammation. A 2nd study enrolled 23 IDDM subjects with advanced periodontitis, who were randomised to treatment (full initial therapy including root planning) or control groups. Only 1 subject failed to complete the study, owing to illness. In this study, a significant response to periodontal treatment was not accompanied by any improvement in metabolic control. These results support the concept that the effect of metabolic control may be predominant in the relationship between IDDM and periodontal health.

Coenzyme Q10 and periodontal treatment: is there any beneficial effect?

Many dentists have been surprised by recent media claims of periodontal benefits with a purportedly revolutionary dietary supplement. The research literature on coenzyme Q10's periodontal effects does not extend to the international English language dental literature, which perhaps explains the surprise. A review of the available literature does not give any ground for the claims made, and selected papers are discussed to show that there is actually some evidence that coenzyme Q10 has no place in periodontal treatment.

Periodontal disease activity: a development strategy for its investigation by means of accurate 3-dimensional clinical measurement

The central problem in all previous approaches to clinical assessment of periodontal disease activity is the use of unidimensional measurement, which implies a number of unjustifiable assumptions. In addition, the use of unidimensional probing measurement has established that there are several distinct problems of validity and reliability in currently available techniques. The present paper begins with an analysis of these matters, leading to an approach to accurate clinical measurement of periodontitis in 3 dimensions, with the possibility of future development of a valid system for assessing the nature of disease activity.

Psychological mood of regular dental attenders in relation to oral hygiene behaviour and gingival health

This study examined the relationship between psychological mood, stress and oral hygiene behaviour in a group of 51 regular dental attenders. Subjects brought a saliva sample for cortisol radioimmunoassay, completed the Hospital Anxiety and Depression (HAD) Scale, were assessed for plaque and gingivitis, and were then instructed in toothbrushing. 5 weeks later, 47 subjects were given a full repeat examination. There was a slight reduction in plaque and gingivitis scores, but no change in mood as assessed by HAD Scale and salivary cortisol concentration. Mean anxiety scores were associated with gingivitis level, and mean depression scores with plaque. Neither mood nor cortisol were predictors of subsequent change in plaque or gingivitis.

A skin window study of neutrophil migration in subjects with localized juvenile periodontitis

This study investigated the effect of a chemoattractant, N-formyl-methionyl-leucyl-phenylalanine (FMLP), upon skin window migration of neutrophils into filters in 5 patients with a history of localized juvenile periodontitis (LJP) and 8 controls. On 2 occasions, each subject had 2 superficial skin abrasions made on the inner aspect of the forearm. Initial periodontal treatment was carried out on the disease group between the visits. On one skin window filters were placed that were soaked in physiological saline, and on the other filters soaked with FMLP. Leading fronts and cell densities were measured in each filter. At visit 1, LJP subjects had significantly lower leading fronts and cell densities. At visit 2, the differences were insignificant. The leading fronts for the LJP group were significantly improved on the second visit. No difference was observed between saline and FMLP. The findings of this study indicate that neutrophil migration is reduced in LJP patients where treatment is not involved, and that FMLP has no effect on neutrophil migration from the skin windows under the conditions of this study.

An in vivo study of neutrophil locomotion in relation to periodontal disease status and local chlorhexidine

Neutrophil migration from skin window abrasions was studied in 10 patients with no history of periodontitis, 10 with localised juvenile or post-juvenile periodontitis, and 10 with chronic adult periodontitis. Filters contained either saline or chlorhexidine (0.002% or 0.02%). The leading front was measured in filters placed for 30 min after cell migration had been established for 2 h. Subjects in the juvenile/post juvenile group showed a reduced range of migration distances, but were still within the normal range when compared with the other 2 groups. Chlorhexidine at 0.002% tended to increase leading front distances, and 0.02% to decrease them. We conclude that: 1) migrating neutrophils in vivo may move less far in patients with a history of juvenile periodontitis; 2) chlorhexidine may inhibit cell migration, possibly decreasing the host response in vivo if applied at current therapeutic concentrations.

Effects of chlorhexidine solution on neutrophil locomotion in vitro

The aim of this study was to ascertain the effect of low concentrations of chlorhexidine on the locomotor behaviour of neutrophils. A special feature was the use of a direct test of chemotaxis. Neutrophils recovered from peripheral blood of healthy adult volunteers were tested for chemokinesis and chemotaxis in the presence of chlorhexidine. A moderate dose-related direct response was observed in respect of both these parameters. It was also apparent that increasing concentrations of the drug inhibited a greater proportion of cells, so that there was total immobility at 0.2 per cent and many cells appeared lysed.

The effect of 1% metronidazole gel in routine maintenance of persistent furcation involvement in human beings

The aim of this study was to test adjunctive insertion of 1% metronidazole gel into furcation areas during periodontal maintenance. Ten patients were selected with paired, contralateral, Class II or III furcation involvements that also bled on constant force probing. Bleeding on probing (BOP) and gingival crevicular fluid (GCF) were measured as experimental variables. Plaque was assessed by dark-field microscopy (DFM). Following routine subgingival maintenance of these sites, a syringe was used to insert metronidazole or placebo gels into the furcations. Sites were re-examined 1 and 3 months after baseline. There was little change in either BOP or GCF. Marked longitudinal changes were found by DFM for both experimental and control sites. Experimental sites were not significantly different when compared with controls at the 5% level of probability.

Visual and tactile observational error: comparative probing reliability with recession and cementoenamel junction measurements

Probing error may arise from several sources, including visual observations and tactile detection of the cementoenamel junction (CEJ). This study examined two types of probe scale in relation to measurements of recession and CEJ from a flexible stent, and two types of probe design in addition, in relation to CEJ detection. 492 sites were studied in six patients with untreated periodontitis. Following stent construction, patients attended for measurement of recession and probing depth. This was repeated after 1 h, and then calculus was scaled in the vicinity of the CEJ. One week later, patients attended for CEJ measurements, which were similarly repeated. Measurements with an offset scale (between marks) were more reproducible in general, though no significant difference was detected between recession scores. The most reproducible detection of the CEJ was with a modified Cross calculus probe with an offset scale. A curious feature of the results was a bias affecting 9% of the recession measurements. It is possible that edematous enlargement of the gingiva occurred after the first measurement of probing depth, and was occasionally sufficient to alter the recession score.

Probing site configuration in patients with untreated periodontitis. A study of horizontal positional error

This study examined the morphology of 487 probing sites in patients with untreated periodontitis, using a constant force probe (0.25 N, 0.5 mm) and flexible stent with guide grooves, at 3 adjacent points per site, 6 sites per tooth. Sites were classified into 9 configuration types according to the relationship of the 3 adjacent points. Duplicate measurements were made and sites were analysed with special reference to whether a slight horizontal movement was likely at the second examination. 60% of individual point probing measurements were exactly reproduced, but only 23% of site configurations. 65% of configuration change was accountable on the basis of slight horizontal shift of the probe. Only 13% of configurations required the postulate of other forms of probing error. These results suggest that probing reproducibility is not always an indication of site reproducibility, and that the variation of probe position in the transverse plane is an important source of probing error, even when a stent is used.

Patterns of oviducal motility in the cow during the oestrous cycle

Microtransducers sensitive to changes in internal diameter were chronically implanted in the oviducts of 5 dairy cows. Motility patterns were recorded throughout 9 oestrous cycles. Cyclic variations in patterns of motility were observed and compared with circulating concentrations of plasma progesterone. Luteal-phase motility patterns were of low amplitude and frequency. The frequency and amplitude of motility increased 3-5 days before behavioural oestrus. This activity consisted primarily of longitudinal muscle contractions, with an interspacing of circular muscle activity occurring during oestrus. Patterns of activity after oestrus were similar to those before oestrus, with activity decreasing 3-5 days after oestrus. Transducers implanted bilaterally in 2 animals permitted observation of asynchronous patterns between right and left oviducts. Preliminary data suggested a higher level of activity in the oviduct ipsilateral to the active ovary. These variations may be due to a local effect, possibly mediated by the functional ovary or the ovum.

Upper anterior tooth mobility. Selected associations in untreated periodontitis

The relationship between buccolingual tooth mobility (TM) and other clinical parameters was studied in 124 upper anterior teeth in 21 patients with untreated periodontitis. Periapical long-cone radiographs were available for 74 teeth in the same population. TM was measured with Mühlemann's macroperiodontometer. Probing depths, attachment levels and bleeding were measured with a constant force probe. Bone levels were estimated from radiographs. Presence of occlusal contact was noted in the intercuspal position and excursive movements of the mandible. Attachment levels showed the highest correlation with TM, and radiographically estimated bone support was the next highest. Results varied according to tooth type: the attachment level of the lateral incisors showed the highest correlation with TM, while probing depths and proximal bone support showed lower associations with TM in all cases. In this population, no association was detected between the presence of occlusal contact and TM, or between inflammation and TM. Multiple and partial correlation analysis indicated that probing attachment level was the most important correlate of tooth mobility.

Short-term effect of Keyes' approach to periodontal therapy compared with modified Widman flap surgery

Keyes' method of non-surgical therapy was compared with modified Widman flap surgery in 9 patients with symmetrical periodontal disease. Following an initial oral hygiene programme, baseline measurements were recorded and paired contralateral areas were subjected randomly to the 2 techniques. 42 teeth receiving surgery were compared with 40 treated by Keyes' method. 6 sites per tooth were scored immediately prior to therapy and 3 months later, using a constant force probe with onlays. Consistent data were recorded for the 6 separate sites, which showed no baseline difference between treatments, slightly greater recession with surgery at 3 months, but no difference between treatments in probing depth and attachment levels. Mean data for individual patients showed similar consistency. Probing depth in deep sites was reduced slightly more with surgery, and there were no differences in bleeding on probing at 3 months. Both techniques gave marked improvements in health. Surprisingly, only 2 subjects preferred Keyes' technique of mechanical therapy, 6 preferred surgery, and 1 had no preference.

Response and fertility of dairy heifers following injection with prostaglandin F2α during early, middle or late diestrus

After an observed estrus, 250 dairy heifers were injected once with 25 mg of PGF(2alpha) either on cycle days 5 through 7 (E), 8 through 11 (M) or 12 through 15 (L). For five days after the PGF(2alpha) injection, heifers were inseminated at about 12 h after estrus was first observed. Observed estrual response rates were 43.0%, 83.6% and 100% for E, M and L, respectively. Average time from PGF(2alpha) to observation of estrus for E, M and L was 59, 70 and 72 h. Conception rates for heifers responding to PGF(2alpha) were 56.8%, 62.1% and 78.3% for E, M and L, respectively. Based on blood samples drawn at the time of PGF(2alpha) injection, progesterone concentration was significantly correlated with response rate but not with conception rate. When compared with M and L, E had a significantly lower response rate and conception rate as well as a shorter period between injection of PGF(2alpha) and observation of estrus.

Initial physical tests of aluminoborate cements in the context of periodontal dressing development

A new glass ionomer cement system (aluminoborate) is under consideration for dental applications, including the possibility of a periodontal dressing material. Following the development of pertinent adhesive and rheological tests, two experimental formulations were selected by a simple screening procedure and subjected to appropriate adhesive tests. One formulation proved satisfactory and was subjected to a rheological test in addition. The possible role of aluminoborates as periodontal dressing materials is discussed.

Subcutaneous tissue response in rats to an aluminoborate cement

In the interests of producing an improved periodontal dressing material, adhesive cements are under consideration. A new glass ionomer system--aluminoborates--shows some potential in this respect, and a relatively soluble formulation was chosen for a simple biological test in rats, by means of implantation in polypropylene tubes. As a positive control, the widely used aluminosilicate cement Aspa was employed, and empty tubes were used as negative controls. A simple scoring system using interval measurements was employed, and showed no difference at the 5% level between the experimental cement and either control, although slight differences were discernible between controls. The study also indicated that the side of a filled tube is not the best control for assessment of reaction at tube ends.

Adhesion of periodontal dressings to enamel in vitro

Adhesion to enamel is an important aspect of periodontal dressing retention. Details of tensile and shear bond strengths are presented for three dressing materials and a positive polycarboxylate control, and the data are discussed with regard to optimum levels of retention. A level of 2 MN/m2 is suggested for shear bond strength, and 1 MN/m2 for tensile bond strength, under the test conditions employed.

Gingival bleeding in an experimental clinical trial design

An experimental clinical trial design is described in which the onset of gingival bleeding was used as an indicator of early gingivitis. Twenty-nine dental students participated in a double-blind crossover trial utilising chlorhexidine as a known plaque inhibitor. The onset of gingival bleeding was assessed in three ways, one of which yielded a statistically significant difference in favour of the active mouthrinse (P = 0.02). The method has a role in screening agents believed to be active against gingivitis.

Validity of an assumption underlying the confirmed bleeding day measurement in an experimental clinical trial

In a clinical trial involving gingival bleeding, one measurement proved far better than the others. It was assumed that this measurement would help to eliminate certain sources of error. This paper examines data from the trial which give support to the assumption.