Effect of diode laser and fluoride varnish on initial surface demineralization of primary dentition enamel: an in vitro study

INTRODUCTION

Previous investigations have demonstrated improved enamel caries resistance after laser irradiation. The purpose of this in vitro study was to assess the caries-preventive potential of 809 nm diode laser treatment of the enamel of primary teeth compared to topical fluoride application.

METHODS

Eighty samples of sound primary teeth were embedded in plastic and stored in saline solution. The enamel surface of 80 samples was polished in an area of 2 x 2 mm. These tooth specimens were randomly assigned to one control and three test groups: (1) no treatment/control; (2) application of 0.1 mg of fluoride varnish (Duraphat) for 6 h; (3) diode laser application (809 nm, 140 mJ, 50 Hz, Ø 600 micro m fibre, contact mode, absorber, 1 min; ORA-LASER01 I.S.T.); and (4) combined application - laser/fluoride varnish. Caries-like lesions were created by pH-cycling. After lesion formation, longitudinal sections were taken and examined by polarized light microscopy.

RESULTS

In the control group, all samples showed lesions up to 30 micro m in depth. After laser application, lesions could be identified in 15 out of 20 samples. Topical fluoride treatment in groups 2 (varnish) and 4 (laser/varnish) completely inhibited the development of caries-like lesions in all samples.

CONCLUSION

In this in vitro investigation, topical fluoride treatment enhances the resistance of sound enamel of primary teeth more effectively than diode laser application.

Insulin Pump Therapy in Patients with Type 1 Diabetes Mellitus: Results of the Nationwide Quality Circle in Germany (ASD) 1999 - 2000

BACKGROUND AND AIMS

Only a few specialised centres in Germany initiated insulin pump therapy before 1990. Initiation of pump therapy involves the participation in a structured treatment and teaching programme (TTP). During the last decade insulin pump therapy has been widely used. The impact of this decentralisation on the quality of care is still unknown. The aim of this trial was both to evaluate the outcome of insulin pump therapy outside specialised centres and to identify features that might be associated with persistently increased HbA1 c levels.

PATIENTS AND METHODS

250 patients with type 1 diabetes mellitus (age 36.0 +/- 13.1 years; diabetes duration 16.1 +/- 9.9 years), who were on continuous subcutaneous insulin infusion (CSII) therapy during 1999 - 2000, were individually included in the study. Second examination was performed one year after participation in the in-patient TTP for insulin pump therapy. Patients were recruited from 21 member institutions of the Working Group for Structured Diabetes Therapy of the German Diabetes Association. Further details were sought by questionnaire on those patients with persistently increased HbA1c (> 1.7 fold of mean normal range.)

RESULTS

One year after participation in the TTP for CSII relative HbA1c (original value/mean normal of the local method [Müller et al., 1999]) decreased from 1.51 (0.9 - 3.2) to 1.44 (0.9 - 3.6) (p < 0.0001), severe hypoglycaemia from 0.46 to 0.12/patient/year (p < 0.001), severe ketoacidosis from 0.08 to 0.05/patients/year (p = 0.003) and hospitalisation from 5.2 to 3.1 days/patient/year (p = 0.002). In 43/207 (17%) the incidence of severe hypoglycaemia was unchanged (before 0.12 and after TTP 0.14/patients/year), there was slight increase in severe ketoacidosis (before 0.15; after TTP 0.23/patients/year) and hospitalisation days were unchanged (before 4.5; after TTP 4.4 days/patients/year). The following factors were associated with adverse outcomes: psychological problems including eating disorders and alcohol abuse (28%), lack of interest in self-management (28%) and social problems (11%). In 28% there was no follow-up treatment by diabetologists specialised in pump therapy.

CONCLUSION

The benefits of insulin pump therapy are improvement of HbA1c, reduction of hypoglycaemia, ketoacidosis and hospitalisation days as well as improved flexibility. It is possible to draw up a list of clinical criteria and service requirements, which are likely to reduce failures.

Cognitive function and quality of diabetes care in patients with Type-2-diabetes mellitus in general practitioner practice

INTRODUCTION/AIMS

The goal of the trial was the assessment of the quality of diabetes control and the cognitive function of all patients with type 2 diabetes mellitus treated in a randomly selected general practitioner practice in Thuringia, Germany. Furthermore possible interactions between patients' quality of diabetes control and their cognitive function should be analysed.

PATIENTS AND METHODS

The investigation comprised all 141 patients with type 2 diabetes mellitus (age 67.3 +/- 10.5 years, body-mass index 29.3 +/- 4.5 kg/m2, patients without insulin therapy: n = 102, with insulin therapy: n = 39) who were patients at the general practitioner practice in Wandersleben, Thuringia, Germany, between November 1999 and April 2000.

RESULTS

The mean HbA1c of all patients examined was 6.33 +/- 1.1% (normal range 3.5-6.8%). 55 patients were treated with diet (HbA1c 5.7 +/- 0.76%) and 47 patients were given oral antidiabetic drugs (HbA1c 6.5 +/- 0.76 %). 27/47 (57.4%) patients were treated with sulfonylurea, 37/47 (78,7%) with metformin, 3/47 (6,4%) with acarbose and 7/47 (14.9%) patients received glinides. 18/47 (38,3%) patients had combinations out of two or more oral antidiabetic drugs. A total of 39 patients with type 2 diabetes mellitus were treated with insulin (HbA1c 7.0 +/- 1.24%). The premorbide cognitive function of the patients was 97.9 +/- 10.0 IQ-points. It was significantly better than the actual cognitive function (91.8+/-13.5 IQ-points, p<0.001). The actual cognitive function showed a correlation with patient's age (r = -0.28, p = 0.001), educational level (r = -0.25, p = 0.006) and profession (r = -0.29, p = 0.001). Performing multivariate analysis the premorbide cognitive function (b = 0.53, p<0.001) and patient's age (b = -0.32, p<0.001) showed associations with the actual cognitive function (R-square =0.36). Associations with the HbA1c (R-square = 0.37) showed the frequency of blood glucose self monitoring (beta = 0.38, p<0.001), the blood glucose value at the time of examination (beta = 0.34, p<0.001) and the diabetes duration (beta = 0.16, p = 0.03). There were no associations between actual cognitive function and other parameters.

CONCLUSIONS

The data from this trial presents evidence which shows that treatment by general practitioners can enable patients both with and without insulin therapy to achieve a high quality of diabetes control. Hence, the results derived from ambulatory evaluations of treatment programmes can not be automatically tansferred to patients treated at hospitals. Regarding inpatient treatment, adapted structured treatment and teaching programmes are mandatory.

Effect of anti-nerve growth factor on early and late airway responses in allergic rats

BACKGROUND

The increased production of nerve growth factor (NGF) has been associated with allergen-induced airway hyperresponsiveness and enhanced airway inflammation in experimental models of asthma. The aim of this study was to investigate whether a local application of anti-NGF to the lungs may affect the allergen-specific early (EAR) and late (LAR) airway responses to ovalbumin (Ova) of Ova-sensitized brown Norway rats.

METHODS

Rats were sensitized systemically with Ova and were boosted twice intratracheally with Ova aerosol using a microsprayer. Two hours before every boost, the animals were pretreated either with aerosolized anti-NGF or with a control antibody. On day 21, all animals were challenged with inhalational Ova aerosol and pulmonary resistance was recorded in anesthetized, orotracheally intubated animals during the early and late asthmatic responses. In addition, differential cell counts from bronchoalveolar lavage and serum immunoglobulin E (IgE) levels were determined 48 h post-Ova challenge.

RESULTS

Pretreatment with anti-NGF significantly attenuated the EAR but had no significant effect on the LAR. Serum IgE levels and inflammatory cell influx into the lungs were not affected by anti-NGF pretreatment.

CONCLUSION

The data from this study suggest that NGF is directly involved in the development of the EAR without affecting the inflammatory airway response or LAR.

The possibility of detecting subgingival calculus by laser-fluorescence in vitro

The aim of the present study was to investigate laser-fluorescence effects on the root surface. The possibility of detecting subgingival calculus should be evaluated to control complete calculus removal after scaling and root planing. Twenty freshly extracted human teeth, partially covered with calculus on the root surface, were fixed on a translation stage. The specimens were irradiated by light from a laser source (diode laser, <1 mW) with a wavelength of 655 nm using the Diagnodent trade mark -system. To simulate the conditions in a periodontal pocket during the measurement procedure, the teeth were covered by a layer of physiological saline solution or blood in order to determine the influence of different inflammatory fluids. The root surface was scanned on a line of about 1 cm in steps of 0.5 mm. The start and end was marked by a notch. The results of the laser-fluorescence detection were compared to clinical and histological findings. Clinically apparent calculus on the root surface was always accompanied with a statistically significant increase of laser-fluorescence values ( p < 0.05). These values were not influenced by the different fluids ( p < 0.05). The laser-fluorescence values were reproducible ( p > 0.05). After scaling, when no debris remained at the root surface, laser-fluorescence values decreased significantly ( p < 0.05). The histological findings supported the clinical results. In conclusion, the present study indicates that laser-fluorescence values on the root surface are strongly correlated to the presence of calculus. This fluorescence effect can basically be used to develop a new detecting system for subgingival calculus in periodontal pockets.

Effect of smoking on risk factors for cardiovascular disease in patients with diabetes mellitus and renal insufficiency

BACKGROUND

Many studies have been published demonstrating a strong correlation between smoking, renal lesions and cardiovascular morbidity and mortality. Possible contributing factors are elevated blood pressure values, changes in vascular reactivity, concentrations of lipids, fibrinogen and carboxyhemoglobin, in patients with diabetes mellitus, the quality of diabetes control and insulin resistance. Other possible risk factors may include advanced glycation end (AGE)-products, total plasma homocysteine and metabolites as well as symmetrical (SDMA) and asymmetrical (ADMA) dimethylarginine. It was the goal of the present trial to investigate the serum concentrations of these >new<, possible risk factors in a selection free population of patients with type 1 and insulin-treated type 2 diabetes mellitus, in patients with chronic renal insufficiency and in renal transplant recipients. The second aim was to analyse the effect of cigarette smoking on the levels of these laboratory parameters.

PATIENTS AND METHODS

A total of 544 subjects (n = 98 patients with chronic renal insufficiency without hemodialysis, n = 84 patients with hemodialysis, n = 50 renal transplant recipients, n = 114 patients with type 1 and n = 147 patients with insulin treated type 2 diabetes mellitus, n = 51 healthy controls) participated in the trial.

RESULTS

Patients with renal insufficiency had significantly higher concentrations of the AGE-products N-epsilon-Carboxymethyllysine (CML) and pentosidine compared with both groups of patients with insulin-treated diabetes mellitus and the healthy controls. In patients with type 1 diabetes there was a positive correlation between HbA1c and the concentration of CML (r = 0.405, p = 0.017) and between the pentosidine-concentration and the serum creatinine-level (r = 0.482, p = 0.001). In type 2 diabetes there was a correlation between CML and diastolic blood pressure (r = 0.239, p = 0.039). In comparison to the healthy controls, patients with renal diseases and patients after kidney transplantation had higher concentrations of total plasma homocysteine and its metabolites. Similar results were found for SDMA and ADMA: Patients with chronic renal insufficiency both with and without hemodialysis had significantly higher values than the renal transplant recipients and healthy controls. A clear influence of cigarette smoking on the levels of the laboratory parameters measured could not be determined in any group; neither in the patients with diabetes mellitus, nor in the patients with renal diseases, nor in the healthy controls.

CONCLUSIONS

The present trial demonstrates an increase in the parameters linked to the development of cardiovascular diseases including total plasma homocysteine, its metabolites, the dimethylarginines SDMA and ADMA and advanced glycation end-products depending on the degree of renal insufficiency. Moreover, in patients with insulin-treated diabetes mellitus, the concentrations of the AGE-products CML and pentosidine seem to be strongly influenced by the quality of diabetes control and blood pressure levels. There was no influence of cigarette smoking on the levels of the laboratory parameters measured.

Electrochemical in situ reaction cell for X-ray scattering, diffraction and spectroscopy

A versatile electrochemical in situ reaction cell for long-term hard X-ray experiments on battery electrodes is described. Applications include the small-angle scattering, diffraction and absorption spectroscopy of lithium manganese oxide electrodes.

Supermode suppression to below -130 dBc/Hz in a 10 GHz harmonically mode-locked external sigma cavity semiconductor laser

We demonstrate supermode suppression to levels below -125 dBc/Hz and -132 dBc/Hz using Fabry-Perot etalons with finesse values of 180 and 650, respectively, for a 10 GHz harmonically mode-locked external sigma cavity semiconductor laser. The laser was hybridly mode-locked using direct electrical modulation in a compact package without the need for an external modulator.

[Changes of periprosthetic bone mineral density in cementless bicontact stem implantation; influence of different parameters--a prospective 4-year follow-up]

AIM

This prospective study describes the periprosthetic BMD (bone mineral density) after implantation of the cementless Bicontact stem over a period of 4 years. Additionally, the influence of several relevant parameters like age, sex, BMI (body mass index) and the influence of the stem-size on the periprosthetic BMD course were investigated.

METHOD

Measurement of the periprosthetic BMD in 36 patients (15 female, 21 male) in a prospective longitudinal study over 4 years with DEXA (dual energy X Ray absorptiometry) of the proximal Gruen zones 1 and 7.

RESULTS

We found a good precision of the method in vivo with a CV (coefficient of variation) of 1.04 %. There was a decline of the periprosthetic BMD at the whole proximal stem (ROI 0) of 20 % in the first 6 months. Afterwards there was a significant increase at the lateral stem (ROI 1) of 3.46 %, in contrast no significant change could be found medially, maybe as a result of a more lateral induction of power. The investigated parameters BMI, age and sex had no influence on the relative course of mineralisation. At stem sizes bigger than 15 the decline of BMD was significantly larger than at the stem sizes smaller than 15.

CONCLUSION

DEXA is a sufficiently precise method to investigate periprosthetic BMD. The postoperative periprosthetic course of mineralisation and the extent of BMD loss in the first 6 months after the Bicontact stem is similar to other periprosthetic BMD courses of prosthesis with a similar design. The course of mineralisation in "smaller" stems is obviously more auspicious than the course of "bigger" stems.

Endodontic and surgical treatment of a geminated maxillary incisor

AIM

A geminated maxillary incisor required complex multidisciplinary treatment to preserve health and restore aesthetics. This report describes the coordination of coronal division, root extraction, bone grafting, endodontic treatment and orthodontics in achieving treatment goals. It is the intention of this report to show how a difficult case could be managed by properly coordinated multidisciplinary care.

SUMMARY

Pulp testing of the geminated central right maxillary incisor gave a normal response. Radiographic investigation indicated a connection of the pulp chambers. Both the mesial and distal root were filled with gutta-percha. The connection between the two root canals was sealed with a flowable dentine-bonded resin. After dividing the crown with a diamond bur, the mesial part of the tooth was removed and the extraction socket was filled with beta-tricalcium phosphate ceramic (Cerasorb). Radiographs taken immediately after surgery and after 6 months showed no periodontal or periapical lesions. No signs of external resorption were identified. The diastema between the central incisors was closed by orthodontic treatment.

KEY LEARNING POINTS

Geminated teeth may present aesthetic and functional problems which require multidisciplinary care. Careful clinical and radiographic examination is essential to decide on the fate of the coronal and root halves involved. A proper coordination between endodontic and surgical treatment may result in maintaining one tooth half, even if a midroot connection between the pulp chambers becomes evident. Orthograde endodontic treatment, hemisection and orthodontics may solve the aesthetic problem of a geminated tooth.

Analysis of the two common alpha-1-antitrypsin deficiency alleles PiMS and PiMZ as modifiers of Pseudomonas aeruginosa susceptibility in cystic fibrosis

Lung disease is the direct cause of death in more than 90% of cystic fibrosis (CF) patients. Proteinase-antiproteinase imbalances are common in CF and alpha-1-antitrypsin (AAT) deficiency. We investigated the hypothesis that the AAT deficiency alleles PiS and PiZ contribute to pulmonary prognosis in CF. Two hundred and sixty-nine CF patients from Southern Germany were included in this study. The serum concentrations of AAT and C-reactive protein (CRP) were determined by nephelometry, and patients were screened by polymerase chain reaction (PCR) and restriction enzyme digest for the common AAT deficiency alleles PiS and PiZ. The onset of chronic bacterial colonization by Pseudomonas aeruginosa (Pae) was correlated with the AAT phenotypes PiMM, PiMS and PiMZ. Only three out of nine CF patients (33%) diagnosed with either PiMS or PiMZ had developed chronic Pae lung infection earlier in their lives. The remaining six patients showing a PiMS or PiMZ phenotype showed a later onset of chronic Pae lung infection. Our results indicate that PiMS and PiMZ are not associated with worse pulmonary prognosis in CF. These data need to be confirmed in studies with a much larger number of cases.

Clinical and microbiological effects of local chlorhexidine applications

AIM

To study the effects of an application of chlorhexidine varnish (40%) on dental plaque.

DESIGN

Randomised controlled clinical trial.

SUBJECTS

40 patients (50% females), aged 25-34 years after undergoing any necessary restorative treatment. Exactly one half of these individuals practiced good oral hygiene, the efforts of the others were poor.

METHOD

Test groups received a chlorhexidine varnish application, the control group received a placebo varnish. Initially and after 2 and 6 weeks, a modified Dentocult SM-test, bleeding on probing, and a plaque index (Quigley-Hein) were recorded.

RESULTS

In contrast to the control group, improvements in plaque index and bleeding on probing scores were found in patients with poor oral hygiene. The results of the Dentocult SM-tests showed a considerable reduction of streptococcus colonisation. The test group with good oral hygiene showed only slight improvement of the examined indices after chlorhexidine application. The index parameters of all patients of the placebo groups remained unchanged over the examination time period.

CONCLUSION

The application of a chlorhexidine varnish reduced the quantity of the Streptococcus mutans colonies significantly and improved clinical parameters in patients with elevated plaque accumulation.

Dynamics of tight and adherens junctions under EGTA treatment

The dynamics of tight junctions (TJs) and adherens junctions (AJs) under EGTA treatment were investigated in Madin Darby canine kidney (MDCK) cells. Detailed information about the behavior of TJ and AJ proteins during the opening and resealing of TJs and AJs is still scarce. By means of the "calcium chelation" method, the distribution and colocalization of junctional proteins were studied with confocal laser scanning microscopy using a deconvolution algorithm for high-resolution images. Colocalization was analyzed for pairs of the following proteins: ZO-1, occludin, claudin-1, E-cadherin and F-actin. Significant differences were found for the analyzed pairs in control cells compared to EGTA-treated cells with respect to the position of the colocalization maxima within the cell monolayers as well as with respect to the amount of colocalized voxels. Under EGTA treatment, colocalization for ZO-1/occludin, ZO-1/claudin-1, claudin-1/occludin, E-cadherin/occludin and E-cadherin/claudin-1 dropped below 35% of the control value. Only for the ZO-1/E-cadherin pair, the amount of colocalized voxels increased and a shift to a more basal position was observed. During the opening of TJs and AJs, ZO-1 colocalized with E-cadherin in the lateral membrane region, whereas in controls, ZO-1 colocalized with occludin and claudin-1 in the junctional complex. The combination of deconvolution with colocalization analysis of confocal data sets offers a powerful tool to investigate the spatial relationship of TJ and AJ proteins during assembly and disassembly of cell-cell contacts.

Measurement of residual phase noise and longitudinal-mode linewidth in a hybridly mode-locked external linear cavity semiconductor laser

We report measurements of the residual phase-noise knee position and longitudinal-mode linewidth of a hybridly mode-locked external linear cavity semiconductor laser as a function of laser cavity length. Excellent agreement between these measurements suggests a direct relationship between rms pulse-to-pulse timing jitter and average longitudinal-mode linewidth. This relationship leads to a fundamental limit in the timing jitter of mode-locked lasers.

Er:YAG laser scaling of diseased root surfaces

BACKGROUND

The removal of calculus and plaque is an essential component of a therapeutic approach to control periodontal disease. Er:YAG laser scaling was recently introduced as an alternative to conventional scaling procedures. In this histological study, the effects of laser instrumentation of diseased root surfaces are compared to mechanical removal of plaque and calculus with ultrasonic instruments and scalers.

METHODS

Areas of subgingival calculus were identified on 40 freshly extracted human teeth. Each of these areas was randomly divided into 2 equal parts. The control site was treated either with scaling and root planing or with an ultrasonic instrument. The test site was cleaned using an Er:YAG laser according to the manufacturer's instructions. The end point of debridement was the inability to mechanically or visibly detect any remaining calculus. After pre- and postsurgical photographs and impressions for scanning electronic microscopic investigation, a plastic embedding technique was used to cut the undecalcified roots into 15 microm thick sections.

RESULTS

Clinically and histologically, scaling resulted in complete debridement at all samples, producing a smooth root surface. At the test sites, laser scaling was accompanied by an increased removal of tissue and roughened surfaces.

CONCLUSIONS

Laser scaling results in an increased loss of cementum and dentin, which should be taken into account in clinical situations.

Ultralow noise and supermode suppression in an actively mode-locked external-cavity semiconductor diode ring laser

We report what is to our knowledge the lowest phase and amplitude noise characteristics achieved to date in a 10-GHz pulse train produced by the active harmonic mode locking of an external-cavity semiconductor diode laser. Supermode noise has also been suppressed below -140 dBc/Hz by use of a high-finesse fiber Fabry-Perot etalon as an intracavity filter. Novel noise sideband measurements that extend to the Nyquist offset frequency suggest a significant advantage in using harmonic (rather than fundamental) mode locking to produce ultralow-noise pulse trains, owing to the relationship between the noise roll-off frequency and the fundamental cavity frequency.