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Purpose: To assess the accuracy of linear measurements of bone loss within infrabony defects on digitized radiographs after digital filtering particularly designed to image periodontal bone loss., Methods: Before surgery, 50 standardized radiographs of 50 infrabony defects were obtained. Intrasurgically the distances from the cementoenamel-junction (CEJ) to the alveolar crest (AC), from the CEJ to the bottom of the bony defect (BD), and the depth of the infrabony component (INFRA) were assessed. All radiographs were digitized and the distances CEJ-AC, CEJ-BD, and INFRA were measured on digitized but unchanged radiographs and after use of the filter., Results: There was a small overestimation of CEJ-AC (0.35-0.68 mm) and underestimation of CEJ-BD (0.84-1.12 mm) and INFRA (0.66-0.76 mm). Accuracy of measurement of the distance CEJ-AC was influenced by vertical angulation difference (P= 0.047) and the intrasurgical CEJ-AC (P= 0.003). Accuracy of CEJ-BD was influenced by intrasurgically assessed bone loss (P= 0.012). Accuracy of INFRA was influenced by individual patient, intrasurgically assessed INFRA (P< 0.001), and filter (P= 0.018).

Purpose: To compare different image processing modes (filters) on the reproducibility and accuracy of the assessment of proximal carious lesions viewed in direct digital radiographs. Variables studied were exposure time and tissue scatter radiation., Methods: Standardized direct digital radiographs of 50 extracted teeth were obtained and 44 areas of proximal caries were detected histologically. Four radiographs were obtained of each tooth using a charge coupled device sensor. Two radiographs were obtained with and two without tissue scatter radiation equivalent (TSRE) each of them at normal exposure time (0.06 second) and underexposed (0.01 second). On each of the 200 radiographs, the central depth (CD) of each carious lesion was measured at 21-fold magnification both on the unchanged image and after use of two different filters (median, median plus inversion). All measurements were repeated after 1 week to estimate reproducibility. Histometric CD assessments provided a gold standard for comparison with the radiographic measurements (accuracy)., Results: Whereas reproducibility was not influenced significantly by any of the investigated parameters, defect type and exposure time influenced the overall accuracy of CD measurements. Basic digital filtering of radiographic images failed to result in statistically significant improvement of the accuracy of CD measurements.

Purpose: To evaluate if the in vitro quality of preventive fissure sealants made with compomer-based materials can be improved by modifying the method of application., Methods: Delton resin-based sealant, Dyract Flow and Dyract Seal compomers were used. The manufacturer's instructions were modified by prolonging the application time of the materials used and by applying the sealer in two layers. Extracted caries-free human molars were fissure sealed under standardized conditions and then exposed to a thermocycling procedure and a dye penetration test. Following the preparation of ground slices the samples were assessed by means of a light microscope and a scanning electron microscope. Statistical analysis of the results was done using a chi-square test., Results: The modified application of the two-compomer-based fissure sealers improved distinctly the quality of such fissure sealants. This was observed with respect to the criteria sealing ability, absence of pores in the sealant and complete filling of the fissure in wide as well as in narrow fissures. Compomer-based fissure sealants applied with the modified technique were equal to conventional resin-based composite fissure sealants regarding sealing ability and complete filling of the fissure. With respect to absence of pores, compomer-based sealants were superior to resin-based composite sealants.

Purpose: To compare the effects of different image processing modes (filters) on the reproducibility and validity of the assessment of interproximal carious lesions viewed in digitized radiographic images., Materials and Methods: Variables studied were film type, exposure time, and tissue scatter radiation. Images were assessed in relation to film type, exposure time and tissue scatter. Standardized radiographs of 50 extracted teeth were obtained and 44 areas of interproximal caries were detected. Six radiographs were obtained of each tooth and digitized using FRIACOM software. Four were made using D-type film with and without soft tissue scatter equivalent at normal exposure time (0.32 seconds) and underexposed (0.16 seconds). Two were made using E-type film with TSE normal (0.16 seconds) and underexposed (0.08 seconds). On each of the 300 radiographs, the central depth (CD) of each carious lesion was measured at 18x magnification both on the unchanged radiographic image and after use of two different filters. All measurements were repeated after 1 week to estimate reproducibility., Results: Histometric CD assessments provided a gold standard for comparison with the radiographic measurements (validity). Whereas reproducibility was not influenced by one of the filters, filter "structure" improved the overall validity of CD measurements. In this study, digital manipulations of radiographic images resulted in statistically significant improvement of the validity of CD measurements.

Purpose: To determine, whether different tooth colored materials and application techniques influence the proximal contact strengths (PCS) in vitro., Materials and Methods: Standardized MO-cavities for direct restorations were prepared into 360 artificial lower first molars. Eight groups were formed (n = 45) and restored with amalgam (1), low (2, 3), medium (4, 5) and high (6, 7) viscosity hybrid composites and compared to the original contact strengths of the unprepared teeth (8). The restored teeth were mounted into a socket simulating physiological tooth mobility. PCS were quantified by measuring the forces necessary for passing the proximal contact with floss under standardized conditions using a universal testing machine., Results: PCS ranged from 1.32 +/- 0.56 N for the low viscosity composite to 9.90 +/- 1.98 N for the Amalgam restoration. Medium (5.65 +/- 1.08 N) and high viscosity hybrid composites (5.90 +/- 1.45 N) inserted in a multi-layer technique showed no statistically significant differences to the original PCS of the unprepared teeth (5.76 +/- 0.53 N).

Purpose: To compare the cleaning efficacy of a battery-powered toothbrush with an oscillating/rotating action (Dr. Best Powerclean) and a standard flat-trimmed manual toothbrush (Elmex super 39) in a single-blind, cross-over clinical study., Materials and Methods: 78 healthy subjects took part in the study. Subjects were asked to abstain from all oral hygiene procedures for 48 hours, after which hard and soft oral tissues were examined. Plaque was then scored using the Turesky modification of the Quigley-Hein Index, and subjects were instructed to brush their teeth for a total time of 1 minute with either one or the other brush, according to a predetermined randomization schedule. Immediately after brushing, plaque was scored again and hard and soft tissues were re-examined. All plaque scoring was carried out by the same investigator who was blind with respect to the brushes used. Subjects were instructed to continue with their usual oral care routine throughout the study period. They were scheduled to return after 12-14 days, having again abstained from all oral hygiene for 48 hours prior to the visit, in order to repeat the evaluation sequence but brushing with the alternative brush. Prior to analysis of the results, data from the two phases of the study were combined., Results: Both toothbrushes were found to be safe as used in the study. Using the non-parametric Wilcoxon test for paired samples, whole mouth plaque scores were found to be reduced significantly from 2.04 +/- 0.60 to 1.57 +/- 0.51 by the Powerclean toothbrush (P < 0.001), and from 1.99 +/- 0.65 to 1.27 +/- 0.52 by the manual toothbrush (P < 0.001). At approximal surfaces, the plaque scores were also significantly reduced from 2.14 +/- 0.0.59 to 1.69 +/- 0.50 for the Powerclean (P < 0.001), and from 2.08 +/- 0.64 to 1.40 +/- 0.57 for the manual toothbrush (P < 0.001). A comparison of the two brushes revealed that the manual toothbrush removed significantly more plaque than the Powerclean, both for the whole mouth and approximal surfaces (P < 0.001). The Powerclean reduced whole mouth plaque by 23.2 +/- 11.5% compared to 37.8 +/- 14.0% for the manual toothbrush and approximal plaque by 20.9 +/- 10.6% and 34.9 +/- 14.0%, respectively. It is concluded that the Dr. Best Powerclean toothbrush is not as effective as a standard flat-trimmed manual toothbrush.

Purpose: To test the hypothesis that simulation of an intrapulpal pressure during the application of dentin bonding systems influences hybrid layer formation in vitro., Materials and Methods: 180 teeth and three different bonding agents were used for shear bond strength measurements and for confocal laser scanning microscopy studies on the dentin-composite interface. The bonding agents (30 teeth each material) were applied without (90 teeth, Group A) and with intrapulpal pressure simulation of 34 cm H20 with water (90 teeth, Group B). 45 specimens from each group were sheared in a testing machine, and 45 teeth from each group were used for CLSM studies after labeling the primer components of the bonding agents with a fluorescent dye., Results: After simulation of pulpal pressure the bond strengths decreased significantly in all groups (Syntac [without/with]: 16.0 +/- 4.5/8.0 +/- 3.7, P= 0.001; Gluma: 13.3 +/- 4.6/8.4 +/- 4.4, P= 0.008; Prime & Bond NT: 14.8 +/- 5.8/8.7 +/- 5.7, P= 0.007; n = 15 each; U-tests). There were no significant differences between the hybrid layer thickness without/with simulation of pulpal pressure (Syntac: 3.6 +/- 0.6/4.1 + 1.2, P= 0.35; Gluma: 3.5 +/- 0.6/3.7 + 0.9, P= 0.49; Prime & Bond NT: 3.5 +/- 0.9/3.8 + 0.8, P= 0.44; n = 15 each; U-tests). In the case of simulation of an intrapulpal pressure, CLSM examination revealed a distinctly shallower penetration of the adhesives into dentin compared to the samples treated without intrapulpal pressure.

The term "nanoleakage" was introduced to describe a specific type of leakage within the dentin margins of restorations. Nanoleakage appears as a consequence of the acid etching procedure allowing the penetration of oral and pulpal liquids such as acids into porosities within or adjacent to the hybrid layer. Nanoleakage is independent from microleakage. The amount of penetration depends on the type of bonding agent and on different parameters of the application technique (e.g. etching time, dentin moisture). Nanoleakage is much less extensive than microleakage and has probably no short-term clinical relevance. The long-term stability of the adhesive bond between dentin and restorative material, however, might be adversely affected. Nevertheless, based on the knowledge to date, acid etching prior to dentin bonding should be performed.

Purpose: To correlate the thickness of the dentin/resin hybrid layer and the influence of different etching times to the composite resin tensile bond strength., Materials and Methods: 775 human molars were prepared by removing the occlusal cusps to expose middle dentin using a microtome saw. Five commercially available dentin bonding agents were applied according to the manufacturers' instructions. Only the etching times were varied. For confocal laser scanning microscopy (CLSM) measurements, 325 teeth were used and the etching times were varied (not etched, 15, 30, 60 or 120 seconds). The primer components or self-priming adhesive, respectively, were fluorescence-labeled by rhodamine B isothiocyanate. In each case, the prepared surfaces were then covered by a layer of composite resin, sectioned and examined using a CLSM in fluorescent mode. The extension of hybrid layers was quantified by measuring the distances between the dentin-composite junction to a visible boundary. For the tensile bond strength measurements (Zwick testing machine), 450 molars were prepared, using different dentin etching times (not etched, 15, 30, 60, 120 and 180 seconds)., Results: A hybrid layer was found in all etched teeth. The CLSM data gave evidence for an exponent-function relationship between the periods of etching and the thickness of the hybrid layer. The highest tensile bond strengths were achieved after 15 s of etching, followed by 30 s and 60 s. Under these etching conditions and irrespective of the bonding agent, bond strengths were significantly higher (P < or = 0.05) than without etching or after 120 and 180 s of etching. There was no linear correlation between the thickness of the hybrid layer and the bond strength.