Enamel surface alterations after repeated conditioning with HCl

Background

The aim of this study was to investigate the influence of etching time with 15 % hydrochloric acid (HCl) on the enamel surface destruction by studying the resulting roughness and erosion depth.

Methods

The vestibular surfaces of 12 extracted, caries free human incisors were divided into four quadrants, and each quadrant was etched with 15 % HCl for different numbers of etching cycles (1×2, 2×2, 3×2 and 4×2 min). Surface roughness and erosion depth were measured quantitatively with optical profilometry, and the surface morphology was imaged with scanning electron microscopy (SEM).

Results

After two minutes of 15 % HCl application a median enamel substance loss of 34.02 μm was observed. Lengthening of etching time (2×2, 3×2 and 4×2 min) resulted in significantly increase in erosion depth to each additionally, between 13.28 -15.16 μm (p < 0.05) ending up in a total median enamel surface loss of 77 μm. Regarding surface roughness no significant (p > 0.05) difference was found between unetched enamel and the etched enamel surfaces.

Conclusion

Repeated 15 % HCl conditioning of the enamel surface increases the depth of the etched surface erosion. However, the total erosion depth is rather shallow and therefore negligible.

Technical and clinical assessment of the use of a new material-based splint in orthognathic surgery

Heat or auto-cured acrylic resins are materials that are commonly used in splint construction. Newly developed light-cured resins hold promise in view of the altered characteristics of the material. The aim of this study was to evaluate how far light-curing resin-based splints can be used in orthognathic surgery. Over a period of 1 year, 141 orthognathic surgeries were planned and performed using randomly chosen light-cured splints versus auto-polymerized splints. The performance of splint fabrication, the model planning and the clinical use were assessed by different measurements. The dental technician, the orthodontist and the surgeon evaluated objective parameters (model damage, fabrication time, accuracy of registration, adjustment time) as well as subjective criteria (handling). This study revealed that the use of light-curing splints significantly improved the accuracy (97.7% versus 81.2% in the case of acrylic materials). Less time was needed for the fabrication and adjustment of the splint. There was concomitantly less model damage to be observed when light-curing resins were used (9.2% versus 83.5%) and subjective measurements revealed significantly better handling of light-curing resin-based splints. Light-curing resin splints used in orthognathic surgery seem to be advantageous.

[Coronary heart diseases and associated risk factors in newly manifested type II diabetic patients over the course of 5 years]

Using the baseline data of the diabetes intervention study (DIS) from 1126 newly manifested type II-diabetics our analysis demonstrates higher mean-values of some components of the so-called metabolic syndrome in patients with ECG-abnormalities indicating coronary heart disease (CHD) in diagnosis of diabetes compared with subjects without ECG-findings. The impact of general risk factors for the prevalence of CHD in diagnosis and after a 5-year follow-up is obviously different in both sexes. In multivariate analysis only systolic blood pressure was persistently a significant predictor in both sex groups. With increasing age life-duration gets as time-related factor importance for the development of CHD. The mathematically demonstrated association of triglyceride levels to the presence of ECG-abnormalities agrees with the results of WHO multinational study of vascular disease in diabetes mellitus. In the interventions as well as in the control-groups diabetic subjects with CHD after 5 year follow-up showed in comparison to diabetics without CHD higher levels of investigated risk factors which develop their pathogenetic effect probably by their clustering impact, because the differences of their mean-values are only in some cases significant. The common lower level of the most risk factors at the intervention group compared with the conventionally treated group is the result of the intervention measures.

[The value of hypertension and metabolic factors on the development of coronary heart disease in type II diabetic patients]

In 1,126 newly manifested type II diabetics of the diabetes intervention study (628 male, 498 female) between 30 and 55 years of age by a univariate and multivariate analysis the influence of atherogenic risk factors on the development of the coronary heart disease was tested. The diagnosis coronary heart disease is based on the ECG at rest (Minnesota-code), in 796 test persons an exercise electrocardiogram was made. In a manifestation of diabetes males with coronary heart disease showed higher mean values for systolic and diastolic blood pressure, body mass index and serum triglycerides than the control group free of coronary heart disease. In females systolic and diastolic blood pressure, uric acid level and age were significantly increased. By means of multidimensional analysis of variance as to the major findings in the ECG at rest (Q/QS type) in males the diastolic blood pressure, in females the systolic blood pressure and the serum uric acid proved to be significant. Minor findings (above all disturbances of repolarisation) were in males significantly associated with the triglycerides and the diastolic blood pressure, in the females with the systolic blood pressure and the age. Test persons with a stage of coronary heart disease which is to be recognized only in the exercise ECG in the behaviour of the mean value of the atherogenic risk factors did not differ from the control group free of findings with the exception of the increased serum triglycerides in the females.

[Cardiologic findings in newly manifested type II diabetics of the diabetes intervention study]

In 1,126 newly manifested primarily purely dietetic manageable type II-diabetics (628 men, 498 women) of the diabetes intervention study (DIS) at the age from 30 to 55 years the prevalence of the ischaemic heart disease was established with the help of the ECG in rest (Minnesota code) and in 70% of the test persons by an additional electrocardiography after work. Including the two parameters in 9.2% of the diabetic men and 26.1% of the women electrocardiographic findings of an ischaemic heart disease could be proved. The proportion of pathological findings of the ECG increased with age. While the proportion of a probable ischaemic heart disease (code 1.1-1.2) in the ECG in rest and with 1.4% the same size in the two sexes, in women, the percentage of a possible ischaemic heart disease (code 1.3, 4.1-4.3/5-5.3/8.3) prevailed with statistical significance after the 45th year of age. The at present numerically largest study on newly detected diabetics of type II gives evidences to the previous cardial lesion when the diabetes is manifest at medium age on the basis of the homogeneity of the number of patients.

[Prognostic significance of the resting ECG of diabetics--results of a 10-year analysis]

On 226 diabetics at the age of greater than or equal to 40 years the prognostic evidence of the ECG after resting using the Minnesota code was prospectively analysed with regard to the life expectancy in the subsequent 10 years. During this period 65 diabetics died, 46 of them of vascular and 19 of another cause of death. Essential results of the analysis are Diabetics with Q/QS types (code 1.1-1.2) as well as repolarisation disturbances (code 4.1-4.3/5.1-5.3) in the ECG showed a higher lethality rate in the observation period (48.8%) than those ones with an ECG unsuspicious of ischaemic heart disease (15.9%). When a hypertension is simultaneously present the prognosis is additionally loaded. The proportion of ECG-findings suspicious of ischaemic heart disease was initially only 62.3% in diabetics with coronary cause of death. A relation between codation pattern and year of death in a temporary interval to the ECG-registration could not be established.