INTERACTION BETWEEN OZONE AND COLD SENSITIVITY IN NORWAY SPRUCE: A FACTOR CONTRIBUTING TO THE FOREST DECLINE IN CENTRAL EUROPE?

Three-year-old clonal saplings of Picea abies L. Karst. were fumigated for 60 d during the summer of 1985 with four different levels of O3 . Visible injury (in the form of severe, uniform brown necrosis and shedding of affected needles) occurred after a frost in November on the older needles of three of the clones which had received over 200 µg m-3 of O3 during the summer, 47 d previously. No visible injury occurred during the fumigation period or on the current (1985) year needles. It is suggested that the results provide preliminary evidence for an enhancement of frost sensitivity by O3 which may be significant in the current wave of forest decline affecting high-altitude forests in central Europe.

Carbon dioxide laser for de-epithelialization of periodontal flaps.

Regeneration of mineralized and soft connective tissue components of the attachment apparatus is the main goal in the treatment of periodontal diseases. Often, apical migration of epithelium (long junctional epithelium) effectively prevents the formation of bone and connective tissue attachment after periodontal surgery. The purpose of the present study was to compare conventional periodontal surgery combined with carbon dioxide laser and conventional periodontal surgery alone with respect to epithelial elimination and degree of necrosis of mucoperiosteal flaps. After signing a consent form, five patients with at least two comparable bilateral periodontal defects needing pocket elimination surgery participated in this study. The investigators randomly divided each side into test and control sites. Each patient received oral hygiene instruction and initial therapy prior to surgery. At surgery, the test site received a sulcular incision and carbon dioxide laser de-epithelialization of the outer and inner aspects of the flap. The control group received reverse bevel incision only. The surgeon performed open flap debridement on all teeth. At the time of surgery, the surgeon did a biopsy of each site and submitted specimens for histologic evaluation. A matched pairs t-test was used to analyze the data. The results show significant differences between the carbon dioxide laser and reverse bevel incision with respect to sulcular (P < or = 0.025) and gingival (external) (P < or = 0.01) flap surface epithelial elimination and tissue necrosis (P < or = 0.005). These results should be replicated with a larger number of subjects. The carbon dioxide laser eliminated sulcular and gingival (external) epithelium without disturbing underlying connective tissue. This finding supports the concept that the carbon dioxide wavelength has little or no effect on tissues beyond the target. However, neither laser nor blade eliminated all the epithelium. Researchers observed chronic inflammation in the control and test sites, with a predominance of plasma cells. Lining the sulcular and gingival (external) lased areas, investigators found coagulation necrosis covered by fibrin and coagulated blood. The laser appears to effectively remove epithelium at the time of surgery; however, future long-term, well-controlled quantitative histologic studies are needed to evaluate the effect of repeated carbon dioxide laser de-epithelialization of the gingival (external) surface of mucoperiosteal flaps at intervals during the healing period.

The relationship between first presentation and subsequent observations in heavy calculus formers.

There are few studies that provide information on the natural history of calculus formation. The purpose of this study is to evaluate the relationship between pre-scaling baseline calculus scores, the time since the last prophylaxis before baseline, and scores 8 weeks after scaling in a group of presumed heavy calculus formers. Scaling and polishing were completed on 203 subjects with Volpe-Manhold Index (VMI) calculus scores of 7 or higher, and the date of the last prophylaxis was noted. All were re-examined after 3 weeks. The group included 45.8% males and 54.2% females; the mean age was 41.74 (range = 24 to 72). Racial mix was 57.6% African-American, 39.9% white, and 2.5% other. The mean baseline VMI score was 24.07 (SD = 15.38, range = 7-97). The VMI scores were directly related (P = < .001) to the date of the last scaling and were highest in subjects whose last scaling was more than 2 years earlier (33.67) and least in subjects whose last scaling was less than 6 months previous (15.12). At 8 weeks the mean VMI score was 9.96 (SD = 7.30; range = 0-41). The VMI scores at this time were inversely related (P = < .05) to the date of the last scaling before baseline and were lowest in subjects whose last scaling was more than 2 years earlier (9.07) and highest in subjects with the last scaling less than 6 months previous to baseline (13.07).(ABSTRACT TRUNCATED AT 250 WORDS)

Clone and soil effects on the growth of young Norway spruce during 14 months exposure to ozone plus acid mist.

Five clones of 3-year old Norway spruce (Picea abies [L.] Karst), planted in a soil from the Bavarian Forest (pH 4.4) or a soil from the Calcareous Bavarian Alps (pH 6.9), were exposed for two successive vegetation periods, in closed environmental chambers, to a pollution treatment consisting of acidic mist (pH 3.0) plus ozone levels of 100 microg m(-3) with episodes of 130-360 microg m(-3); control trees were exposed to mist of pH 5.6 and ozone levels of 50 microg m(-3). Climatic and pollution protocols followed the diurnal and seasonal pattern characteristic for the Inner Bavarian Forest in Southern Germany, an area affected by the new-type forest decline. Biometric parameters were strongly related to clone and soil. Pollution treatment had a limited effect on only a few growth parameters. The stem diameter growth increment of two clones was reduced by pollution treatment in both soils, a third clone was affected in the acidic soil only. Two other clones were not affected at all. Stem volume increment of three clones, calculated as D(2)H, was reduced by pollution treatment in the neutral soil, a fourth clone was affected in the acidic soil only. Bud break was either delayed (two clones) or accelerated (two other clones) by treatment. Depending on soil and clone, needle yellowing was observed in previous years' needles in both treatment and control trees exposed to increased light intensities. The 'spotted' yellowing was not identical to symptoms found in forest decline areas and was most likely a consequence of nutrient deficiencies during the vegetation period preceding the experiment. The results of this experiment are discussed with regard to field observations and forest productivity. The complex pattern of growth responses resulting from interactions between air pollution, soil and genetic factors is considered to reflect different susceptibilities of trees to air pollutants.

Effects of ozone, acid mist and soil characteristics on clonal Norway spruce (Picea abies (L.) Karst.)--overall results and conclusions of the joint 14 month tree exposure experiment in closed chambers.

This paper summarizes and evaluates the main findings of 14 preceding papers related to the joint 14-month tree-exposure experiment carried out by the 'Munich Working Party on Air Pollution' at the GSF, Munich, FRG, from July 1986 to September 1987. The experiment tested the hypothesis that an interaction of ozone/acid mist/soil/extreme climatic conditions is the cause of decline of Norway spruce (Picea abies (L.) Karst.) at higher altitudes of the Inner Bavarian Forest. The main findings of the individual studies are presented and their implications for the hypothesis are discussed. Clear effects of soil and genetic factors (differences between clones), for example on growth and frost resistance were found. Treatment with O(3)/acid mist was shown to have effects on plant biochemistry, physiology, histology/ cytology, and growth. The wide scattering of these effects, and the lack of a consistent pattern of response across all clones does not permits a firm conclusion on the validity of the experimental hypothesis. These effects were not confounded by the nutrient stresses imposed during the initial exposure period and were not found to be cumulative during repeated treatments, as was proposed by the hypothesis. It is concluded that the experimental evidence does not indicate that ozone/acid mist are major factors to explain the Norway spruce decline on acidic sites at higher altitudes of the Inner Bavarian Forest and probably similar forest areas.

Effects of ozone, acid mist and soil characteristics on clonal Norway spruce (Picea abies (L.) Karst.)--an introduction to the joint 14 month tree exposure experiment in closed chambers.

This paper introduces a series of publications referring to a single 14-month laboratory study testing the hypothesis that the recent decline of Norway spruce (Picea abies (L.) Karst.) at higher elevations of the Bavarian Forest and comparable forests in medium-range mountains and in the calcareous Alps is caused by an interaction of elevated ozone concentrations, acid mist and site-specific soil (nutritional) characteristics. The effect of climatic extremes, a further important factor, was not included as an experimental variable but was considered by testing of the frost resistance of the experimental plants. Results of these individual studies are presented and discussed in the following 14 papers. Plants from six pre-selected clones of 3-year-old Norway spruce (Picea abies (L.) Karst.) were planted in April 1985 in an acidic soil from the Bavarian Forest, or a calcareous soil from the Bavarian Alps. After a transition period, plants were transferred, in July 1986, into four large environmental chambers and exposed for 14 months to an artificial climate and air pollutant regime based on long-term monitoring in the Inner Bavarian Forest. The climatic exposure protocol followed realistic seasonal and diurnal cycles (summer maximum temperature, 26 degrees C; total mean temperature, 9.8 degrees C; winter minimum, -14 degrees C; mean relative humidity, 70%; maximum irradiance, 500 W m(-2); daylength summer maximum, 17 h; winter minimum, 8 h). Plants were fumigated with ozone, generated from pure oxygen (control: annual mean of 50 microg m(-3); pollution treatment: annual mean of 100 microg m(-3) with 68 episodes of 130-360 microg m(-3) lasting 4-24 h), and background concentrations of SO(2) (22 microg m(-3)) and NO(2) (20 microg m(-3)); windspeed was set at a constant 0.6 m s(-1). Plants were additionally exposed to prolonged episodes of misting at pH 5.6 (control) and pH 3.0 (treatment). Simulation of the target climatic and fumigation conditions was highly reliable and reproducible (temperature +/-0.5 degrees C; rh+/-10%; ozone+/-10 microg m(-3);SO(2) and NO(2)+/-15 microg m(-3)).

Effects of low-level long-term ozone fumigation and acid mist on photosynthesis and stomata of clonal Norway spruce (Picea abies (L.) Karst.).

Four clones of 3-year-old Norway spruce (Picea abies (L.) Karst.), grown on two soils, were from July 1986 to September 1987 exposed to ozone fumigation (50 microg m(-3) as a control, 100 microg m(-3) plus peaks between 130 and 360 microg m(-3) as treatment) and acid mist of pH 3.0 (versus mist pH 5.6 in the control). Climatic conditions, identical for both control and treatment, followed a diurnal and seasonal pattern characteristic of medium high altitudes of the Bavarian Forest, an area affected by the new-type forest decline. Gas-exchange measurements were carried out on the plants from December 1986 until the end of the 14-month's exposure using a series of climate-controlled minicuvettes. ANOVA of the four clones investigated towards the end of the experiment gave hints of a treatment-related depression of the photosynthetic capacity of the previous year's needles (age-class 1986). Within this age-class only one of the clones (11) showed a significant treatment effect, indicating an age-class dependence and a genetic influence of the treatment-related depression of the photosynthetic capacity. The current year's flush was not impaired through the ozone and acid mist exposure. Analysis also revealed clear effects of soil, clone and needle age on photosynthetic parameters.

A comparison of two prophylaxis angles: disposable and autoclavable.

In a clinical trial, the authors evaluated the effectiveness of stain, plaque and debris removal, as well as patient and hygienist acceptance, of the disposable prophylaxis angle vs. the autoclavable prophylaxis angle. Thirty patients received a dental prophylaxis by hygienists for up to 45 minutes. A clinician performed blinded pre- and post-prophylaxis evaluations for stain, plaque and debris. A matched pairs t-test determined significant differences (P < .05) between groups. Significantly less stain, plaque and debris remained following use of the disposable vs. the autoclavable angle.

A clinical evaluation of a resin-modified. Glass ionomer restorative material.

Compomers, resin-modified glass ionomers, were developed to improve the physical properties and clinical handling of glass ionomers. Compomers can be designed to be light-activated and used as restoratives or liners. This article reports data collected up to 12 months after placement of both compomer restorations and liners and is part of an ongoing study evaluating the performance of this material. Based on this data, the authors conclude that this new generation of light-activated glass-ionomer restoratives provides clinical results comparable to those recorded for composite resins at 12 months.

Microleakage of Class 5 composite resin restorations: a comparison between in vivo and in vitro.

The purpose of this study was to determine if a difference exists in microleakage between in vivo and in vitro class 5 composite resin restorations using two variations of a bonding resin (Universal Bond 2 and Universal Bond 3). Class 5 cavities were prepared in 24 matched pairs of teeth on the buccal and lingual surfaces. One tooth of each pair was prepared and restored in vivo and the other in vitro. After preparation and enamel etching, Universal Bond 2 was randomly applied to one surface of each tooth in the pair and Universal Bond 3 to the other surface. Composite resin (Prisma AP.H) was placed in each preparation, light cured, and finished using a standard technique. The in vivo samples were extracted approximately 6 weeks after placement of the restorations. The in vitro samples were thermocycled for 540 cycles (5 to 55 degrees C/1-minute dwell time). All teeth were stained with silver nitrate and longitudinally divided. The teeth were scored on a ranking system of 0 being no leakage to 4 being leakage to the pulpal wall of the preparation. A Wilcoxon matched pairs signed rank test was performed on the data (P < or = 0.05). There were no statistically significant differences in microleakage between restorations using Universal Bond 2 and Universal Bond 3. There were statistically significant differences when comparing the in vivo and in vitro restorations. More microleakage occurred in the in vitro restorations.

Microleakage in facial and lingual Class 5 composite restorations: a comparison.

The purpose of this in vitro study was to determine if there is a difference in microleakage between facial and lingual enamel and cementum using two different evaluation techniques. Class 5 preparations were made in 50 teeth on the facial and lingual tooth surfaces and restored using dentin bonding and composite resin. The teeth were thermocycled, silver nitrate stained, and longitudinally sectioned into mesial and distal halves through each restoration. The mesial half was scored using a rank order system. A Kruskal-Wallis one-way ANOVA was performed. The distal half was scored by measurement, and a two-sample t-test was performed. There were no statistically significant differences (P > or = 0.05) in microleakage between facial and lingual tooth enamel or cementum surfaces using either measurement technique.

Urgent treatment in operative dentistry.

This article has described the treatment for a variety of restorative situations requiring urgent treatment. Successful management of these situations begins with a thorough knowledge of their possible causes and is reinforced by a careful history and a complete examination using all available diagnostic tools. By applying modern treatment modalities we have the ability to reduce the pain and discomfort associated with urgencies classified as restorative in nature.

A 5- and 8-year clinical evaluation of a posterior composite resin.

Class I and II posterior composite resin (Ful-Fil) restorations were placed and were clinically evaluated, according to the US Public Health Service criteria, at baseline, 6 months, 5 years, and 8 years. At 5 years/8 years, alpha scores were assigned to the following percentages of restorations: 16%/31% for color match; 65%/62% for marginal discoloration; 74%/54% for cavosurface marginal discoloration; 100%/100% for axial contour; and 81%/65% for anatomic form. At 5 years/8 years, 56%/33% of Class II restorations had tight proximal contacts; 45%/44% had light contacts; and 0%/22% had no contacts. Transient postoperative sensitivity was reported in 6% of the restorations. Indirect evaluation indicated that there was an average of 64 +/- 35 microns of wear at baseline (because of overfinishing), 105 +/- 67 microns at 6 months, 217 +/- 76 microns at 5 years, and 253 +/- 82 microns at 8 years. At 5 years, three of the restorations, and at 8 years, four additional restorations, were clinically unacceptable because of recurrent caries and/or excessive wear. Final success rates of 90% and 77% at 5 and 8 years, respectively, were calculated.

Nurses' oral health assessments of nursing home residents pre- and post-training: a pilot study.

The purpose of this study was to determine if instruction in how to perform the MDS (Minimum Data Set) oral health assessment and RAP (Resident Assessment Protocol) Summary required by federal regulations will improve nurses' accuracy of the assessments. Fifty residents, admitted within 90 days before a training lecture, were assessed by 18 nurses. A 30-minute training session demonstrated how to perform an oral examination, including hands-on practice under a dentist's supervision. Seven to ten days after the lecture, the nurses re-examined the same residents. These assessments were compared with the admission assessments and a dentist's findings (reference). The results of this study indicate that a 30-minute training session made a significant difference in improving nurses' accuracy in completing the assessments with regard to oral health status and treatment need.

The effect of nurses' background on performance of nursing home resident oral health assessments pre- and post-training.

The purpose of this study was to determine the effect of nurses' background on their accuracy in determining oral health status and treatment need of newly admitted nursing home residents before and after tutoring. Eighteen nurses examined 50 nursing home residents before and after an In-service training lecture. Examinations performed by a dentist served as reference. Background items evaluated were: regularity of each nurse's own dental visits; years since graduation from nursing school; length of experience in an LTC facility; and training received in oral health care. At the second evaluation, nurses greatly improved the % agreement on all items. The results of this study indicate that, regardless of background characteristics, the combination of training, the presence of the dentist, and knowledge that they were in a study appeared to improve nurses' performance on the assessment. Before training, more experienced nurses were better able to determine hard tissue abnormalities than their less experienced counterparts; before training, neither group performed well in assessing soft tissue lesions. Therefore, improvements in basic nursing training in this area appear to be necessary.

Clinical guidelines for managing mandibular dysfunction.

Temporomandibular disorders are a class of orofacial pain that represents a management challenge to practitioners. This article presents a definition, diagnostic classification, screening mechanism, symptomatology, and management guidelines for a sequential approach to treating temporomandibular disorder patients.

Percutaneous injuries among dental health care workers.

To evaluate percutaneous injuries among dental health care workers this survey posed two questions: Is there a difference in the number of percutaneous injuries occurring among dentists, dental hygienists, and dental assistants, and Is there a difference in the number of injuries that occur intraorally or extraorally among dental health care workers as a whole, and within each occupational group? This prospective study included demographic information and an incident report. The incident report tabulated type of injury (intraoral or extraoral), procedure during which the injury occurred, and type of instrument that caused the injury.