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Biomedical subjects

B Hugo

Publications and source records attributed to B Hugo.

At least 19 recordsLinked to original sources
PubMed2001

Comparison of photo-activation versus chemical or dual-curing of resin-based luting cements regarding flexural strength, modulus and surface hardness.

This study investigated the efficiency of chemical activation of dual-cure resin-based luting cements as compared with light- and dual-curing. Curing was performed by (i) mixing base and catalyst without subsequent irradiation (chemical curing=CC), (ii) mixing base and catalyst with direct irradiation (dual-cure=DC) or with (iii) irradiation through 2.5 mm of leucite-reinforced glass-ceramics (IPS Empress, Ivoclar) (dual-cure through porcelain=DCtP), (iv) using only the base paste with direct irradiation (light-curing=LC) or with (v) irradiation through porcelain (light-curing through porcelain=LCtP). Specimens of four fine-hybrid DC resin composites and one self-cure hybrid resin composite (only CC) were prepared and tested after 24 h for flexural strength, modulus of elasticity (ISO 4049) and surface hardness (Vickers). For all materials and parameters, dual-curing produced higher values than LC, even when irradiation was performed through porcelain. Following self-curing without photo-activation, flexural strength was 68.9-85.9%, the modulus 59.2-94.5% and Vickers hardness 86.1-101.4% of the corresponding values obtained by dual-curing with direct irradiation. Light-curing through porcelain as compared with direct irradiation reduced the values for most parameters and materials. In contrast, dual-curing maintained flexural strength for all, the modulus for three and the hardness for one of the materials. The mechanical properties of the self-curing resin cement ranged between those of the DC materials.

Aluminum Silicates↗
PubMed2001

[In vivo study of small class II composite fillings].

This clinical trial aimed at studying the medium term performance in routine clinical practice of drop-shaped Class II resin composite restorations. 111 preparations were completed with the Sonicsys micro-tips (KaVo) and filled with either of two light-cured composites (Tetric Flow, Tetric Ceram, Vivadent, Schaan, Liechtenstein) by 11 dentists in a university clinic. The restorations were evaluated after half a year and then annually, using the US Public Health Service criteria. After one to three years of service nearly all restorations were clinically successful and acceptable for continued use. In four cases, incomplete caries excavation was the cause of failure. We conclude that the drop-shaped Class-II-resin composite restoration should be considered a routine operative treatment for small proximal lesions in posterior teeth.

Adult↗
PubMed2001

[In vitro study of marginal quality of small approximal composite fillings].

The aim of the study was to compare different preparation methods and filling techniques for class II microcavities in vitro. The following methods were evaluated: Sonicsys halftorpedo, Sonicsys halfsphere, Sonicsys approx, Siplus, Piezo cavity system and rotating finishing bur. Every cavity type was obturated with a flowable (Tetric flow) and with a hybrid composite (Tetric ceram). One group consisted of prefabricated ceramic inlays (Sonicsys approx) and one group was filled with a three-site light curing technique. This resulted in 128 composite fillings. The evaluation of the quality of the margins under the SEM demonstrated a statistically significant higher percentage of perfect margins for Siplus compared with the PCS-System (88% versus 58% perfect margins). Marginal adaptation before and after thermocycling demonstrated the following results: Bewelled margins showed in general better adaptation than box-shaped cavities. Similar results were found for normal and flowable composites. Microcavities with occlusal access prepared with the sonicsys halfsphere showed in general better marginal adaptation in comparison to the other methods tested. It was concluded that simple obturation techniques can lead to a stable adaptation of the margins.

Composite Resins↗
PubMed2001

[A retrospective in vivo study of Sonicsys approx restorations].

The purpose of this retrospective study was to determine the longevity and quality of Class II resin composite restorations with Sonicsys approx inserts placed in private practice. In 79 patients 213 composite restorations with margins in enamel and in dentin were evaluated clinically using a modified version of established USPHS-Criteria. The mean time in clinical service was 18+-8 months. The majority of the restorations investigated were rated as "good" (Alpha) or "clinically acceptable" (Bravo). In more than 90% sufficient proximal contact points were evaluated. Seven restorations had no contact to their adjacent tooth. Only one failed after an average period of 18 months in clinical service because of loss of the ceramic insert and was replaced. It is concluded that the composite restoration in combination with Sonicsys insert is an appropriate system for the restoration of Class II lesions in premolar and permanent molar teeth.

Ceramics↗
PubMed2000

Comparison between a plasma arc light source and conventional halogen curing units regarding flexural strength, modulus, and hardness of photoactivated resin composites.

The plasma arc curing light Apollo 95 E (DMDS) is compared to conventional curing lights of different radiation intensities (Vivalux, Vivadent, 250 mW/cm2; Spectrum, DeTrey, 550 mW/cm2; Translux CL, Kulzer, 950 mW/cm2). For this purpose, photoactivated resin composites were irradiated using the respective curing lights and tested for flexural strength, modulus of elasticity (ISO 4049), and hardness (Vickers, Knoop) 24 h after curing. For the hybrid composites containing only camphoroquinone (CQ) as a photoinitiator (Herculite XRV, Kerr; Z100, 3 M), flexural strength, modulus of elasticity, and surface hardness after plasma curing with two cycles of 3 s or with the step-curing mode were not significantly lower than after 40 s of irradiation using the high energy (Translux CL) or medium energy conventional light (Spectrum). However, irradiation by only one cycle of 3 s failed to produce adequate mechanical properties. Similar results were observed for the surface hardness of the CQ containing microfilled composite (Silux Plus, 3 M), whereas flexural strength and modulus of elasticity after plasma curing only reached the level of the weak conventional light (Vivalux). For the hybrid composites containing both CQ and photoinitiators absorbing at shorter wavelengths (370-450 nm) (Solitaire, Kulzer; Definite, Degussa), plasma curing produced inferior properties mechanical than conventional curing; only the flexural strength of Solitaire and the Vickers hardness of Definite reached levels not significantly lower than those observed for the weak conventional light (Vivalux). The suitability of plasma arc curing for different resin composites depends on which photoinitiators they contain.

Composite Resins↗
PubMed1999

[Oscillating procedures in the preparation technic (I)].

An optimal preparation technique should meet the following requirements: a cavity that does not extend beyond the carious lesion; maximum preservation of sound tooth substance, preparation and margin design adapted to the requirements of the restorative material and its adhesion properties, prevention of adjacent tooth damage, and low technique sensitivity. Oscillating instruments with one diamond-coated and one polished surface have been developed to overcome the limitations of conventional preparation designs dictated by rotary burs. Previously untreated carious lesions were prepared using a modified air-scaler handpiece (Sonicsys) with various working tips allowing interproximal cavity preparation with minimal extension and a low risk of damaging the neighboring tooth. Another oscillating system is based on the EVA-System. It uses files for the preparation of interproximal bevels and for the finishing of margins of interproximal box, crown and veneer preparations. These oscillating instruments overcome the major limitations of rotary burs for tooth preparation and facilitate conventional cavity preparation. In addition, they allow the use of cavity designs that could not be achieved with conventional instruments.

Crowns↗
PubMed1999

[Oscillating procedures in the preparation technic (II). Their development and application possibilities].

The acceptance and use of amalgam as an everyday filling material is decreasing. Today, direct composite fillings are widely used to restore even extensive lesions in premolars and molars. The sonoabrasive method presented here uses special working tip geometries (SONSICSYS approx) to a allow a "finishing preparation" of standardized interproximal cavities. In this process, the "negative shape" of the working tip is transferred to the tooth. It is now possible, for the first time, to accurately restore class II box cavities using prefabricated ceramic inlays. Complicated layering techniques are no longer necessary and there is no risk of compromising interproximal contacts remaining occlusal defects can be restored with conventional composites. The use of special SONICSYS working tips for ceramic and cast gold cavity preparations ensures precise cavity geometries with "close-to-perfect" margins. The sonoabrasive method greatly lowers the technique sensitivity of such difficult types of preparations.

Bicuspid↗
PubMed1999

A highly sensitive, nested polymerase chain reaction based method using simple dna extraction to detect malaria sporozoites in mosquitos.

Dried Anopheles farauti mosquitos caught in Solomon Islands in 1990 were examined for malaria sporozoites by ELISA and nested polymerase chain reaction (PCR). Only heads and thoraces were used. Plasmodium genus-specific nested PCR amplifications were carried out on all samples. Of the 402 pools of mosquitos that were processed, 30 were positive for malaria. Nest 1 products of positive samples were subjected to further PCR amplifications with species-specific primers for P. falciparum and P. vivax. Twenty pools were positive for P. vivax by PCR while only 7 were positive by ELISA. For P. falciparum 2 pools were positive by both ELISA and PCR, and one of these was a pool which was positive for P. vivax by PCR and ELISA. Thus the sensitivity of PCR for P. vivax was 100% while the specificity was 96.7%. For P. falciparum the sensitivity and specificity were 100%. The PCR technique is highly sensitive and can be used on dried mosquitos which makes it a valuable tool for determining sporozoite rates of mosquitos, even in remote areas.

Animals↗
PubMed1998

Preparation and restoration of small interproximal carious lesions with sonic instruments.

Partially diamond-coated oscillating preparation instruments are particularly suited for cutting minute interproximal cavities. This review presents an oscillating preparation system with newly designed working tips for cutting and finishing proximal microcavities. Analysis of the margins of various cavity designs prepared with this instrumentation exhibited outlines that were essentially free of defects. The method and instruments presented allow cutting of minute first intervention cavities of interproximal lesions with defect-related extension. Enhanced margins can be attained without concomitant damage to adjacent tooth surfaces.

Bicuspid↗
PubMed1996

Assessment of the combined orthodontic-surgical treatment from the patients' point of view. A longitudinal study.

In a longitudinal study, 40 patients who underwent a combined orthodontic-surgical treatment, were interviewed 4 weeks before operation and 1 week and/or half a year after surgery in order to evaluate patients' expectations and appraisal of the operation and their psycho-social situation. The comparisons between the patients' pre- and postoperative statements yielded the following picture: the patients showed a high degree of satisfaction with the result of the operation. They judged their postoperative facial appearance, with the help of a "semantic differential', to be significantly more attractive. Satisfaction also was expressed in a higher degree of psychological well-being and thus an increase in self-confidence and motivation. Postoperatively, the "Giessen test' showed also a distinctly positive change of the patients' mood and improved experiences with social interaction. Before the operation almost half of the patients feared sensitivity loss or disturbance. One out of 5 patients did in fact suffer from this problem--but not from pain--half a year after the operation. Some patients felt they had received insufficient prior information about the procedure and the risk of the operation. In spite of all burdens for the patients, the assessment of the result of the operation is (generally) positive, not only from the medical point of view.

Adolescent↗
PubMed1995

Removal of hard tooth structure by ROOTSHAPE root planing files used with a modified EVA contra-angle.

The results of numerous recent investigations indicate that root contamination with bacteria and endotoxins is limited to the root surface only. Therefore, methods on root surfaces instrumentation that preserve root substance should be focused on. Newly available instruments or treatment systems should be evaluated for their root substance-removing potential. The devices for root planing presented here comprised specific files (Rootshape) (with diamond-coating on their convex working surfaces used in conjunction with a water-spray-cooled contra-angle head transforming rotational movements into translatory oscillations. The substance-removal potential of rigid and flexible files with diamond coatings of 2-4, 15, 25 and 40 microns compared with that of regular hand curettes, was evaluated under various working forces. The results demonstrated, that depending on the grit size of the diamond coating, the Rootshape files removed less and in no instance greater amounts of root surface substance than did hand instruments.

Analysis of Variance↗
PubMed1995

[A mathematical model for the treatment of root surfaces with rigid and flexible instruments].

The objective of this study was to assess the accessibility of root surfaces using stiff instruments in order to evaluate the advantages of a new flexible instrument-set for the treatment of periodontally diseased roots. 100 extracted human teeth were sectioned and histologically prepared. They were divided into two groups each containing 50 sections. Group I showing the interproximal, group II the buccal/lingual morphology. Slides were taken of each section under a constant magnification (3.2x) and a selected number of distances and angles were measured on each section. Using trigonometric functions the following parameters were calculated and set in relation with hypothetical probing depths ranging from 0-15 mm: 1.) instrument length; 2.) change of the instrument angulation; 3.) theoretical deflection of the gums. Statistical analysis was performed using Student's t-test. For a given probing depth the instrument length was independent of the sites and the deflection of the gums. When a deflection of the gums was assumed, the instrument angulation was constant; an exponential decrease of the angulation with increasing probing depth was found with gum deflection. The deflection was increasing with increasing probing depth, showing statistically significant differences between interproximal and buccal/lingual sites (p < or = 0.05). In conclusion the instrument length seems not to be an impeding factor for the accessibility of root surfaces in contrast to the instrument angulation and the fact that teeth are encircled by the gum. Due to morphological reasons stiff instruments seem to be inferior to flexible instruments when a non-surgical root treatment is performed.(ABSTRACT TRUNCATED AT 250 WORDS)

Dental Scaling↗
PubMed1995

[Personnel and instrumental differences in the treatment of root surfaces. A comparison on a phantom model].

The treatment of root surfaces in periodontal lesions with mechanical instruments is becoming more and more popular as an alternative to the conventional treatment with curets. In this in-vitro study a phantom head with a simulated periodontitis was used. The aim of this investigation was to determine the percentage of the subgingival non-treated root surfaces after treatment with different instruments and by different persons. Newly developed mechanical file instruments (Rootshape) were tested. Hand curets served as control group. The treatment of the teeth was carried out by three groups, each including 4 people. Group one were dental hygienists (DH), group two dentists with (Spez) and group three dentist without (Zaz) experience in the therapy of periodontal diseases. They were asked to perform a scaling and root planing on six teeth (16, 21, 24, 36, 41, 44) both with curets and Rootshape files. The size of the non-treated areas was subsequently determined planimetrically and expressed as percentage of the entire subgingival root surface. Independent of the group the percentage after file treatment was significantly lower (mean 9.85 +/- 7.78%) than that after curet-treatment (mean 14.74 +/- 10.20%). Significant differences were found when the three groups were compared after treatment either with files or curets (DH 9.61 +/- 8.02%, Spez 12.11 +/- 8.01%, Zaz 15.18 +/- 11.01%; p < 0.001). Zaz working with files achieved as good results as DH or Spez with curets (p < or = 0.05). The results indicate that the files represent an alternative to hand instruments concerning the accessibility of root surfaces.

Dental Hygienists↗
PubMed1992

[The effect of 2 finishing methods on the micromorphology of the proximal box margin. An in-vivo study].

Minipreparations of class II cavities often are not employed in daily practice mainly because adequate instruments for finishing the axial box margin and the proximo-cervical curvature were not available. The purpose of this in vivo study was to assess the morphology of the proximal box margin after finishing with two different methods. 81 class II minicavities for amalgam restorations were prepared by 4 dental practitioners. One method for finishing the axial box margin and the proximo-cervical curved border was the use of a modified EVA-System with the total amplitude reduced to 0.4 mm and a highly flexible file (Cavishape, grain 25 microns). The other method was the use of an axial margin trimmer. The micromorphology of the two methods was investigated by means of scanning electron microscopy and a score system as described earlier (Lussi et al. 1987). The margins of the axial box as well as of the proximo-cervical curvature were significantly better finished with the EVA-System and the highly flexible file compared to the axial margin trimmer (p < 0.001). The finishing time for the box margin was not significantly different using the EVA instrument or the axial margin trimmer. These findings confirm other in vitro investigations. This in vivo study shows that the modified EVA instrument with the highly flexible file (Cavishape, grain 25 microns) is clearly superior to the axial margin trimmer in finishing the box margin. This device allowed a significant better finishing of the axial box margin and the proximo-cervical curvature of minicavities in daily practice.

Chi-Square Distribution↗
PubMed1992

[The preparation of enamel margin beveling in proximal cavities].

Minicavities for posterior composite resin restorations were prepared in 24 caries-free teeth. The aim of this in vitro study was to evaluate the micromorphology of the proximal cavosurface bevel. The cavosurface bevel has been employed for many years as an accepted modification for composite restorations in permanent anterior teeth. The bevel provides more exposed enamel rod ends available for bonding. Using the acid-etch technique the resin-enamel bond is stronger with etched transverse sections of enamel prisms than with longitudinal sections. Enamel in the proximal and gingival wall of class II cavity preparations for restoration with composite should be beveled because prism direction is at right angles to the surface. The aim of this study was therefore to compare two methods for beveling the box margins of small proximal cavity preparations. One method for the preparation of the proximal bevel was the use of a modified EVA-System with the total amplitude reduced to 0.4 mm, the fixation of the file position and a new developed file (Bevelshape, grain 40 microns). The form of this file was modified in order to produce a short cavosurface bevel of the gingival and proximal wall without danger of damaging the adjacent tooth. The other method was the use of an axial margin trimmer. The micromorphology of the two methods was investigated by means of scanning electron microscopy and a score system as described earlier (Lussi et al. 1987). Statistical analysis revealed significant differences between the two groups. As compared to the axial margin trimmer the new device allowed a significant better finishing of the proximal bevel (p < or = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Dental Caries↗
PubMed1992

[The status of the dentition in 2 Swiss population groups before the introduction of refined sugar].

Caries and parodontitis have been one of the most spread diseases of mankind. In an archaeological study, 53 graves of Bernese patricians were exhumed. 22 skulls of adults with 392 teeth were examined. They lived between the 16th and the 18th century in the community of Worb BE. In some cases identification could be accomplished by comparison of oil paintings with skulls, using a computerized technique. The aim of this study was to evaluate the prevalence of caries, the loss of periodontal bone, the amount of calculus and of abrasion. To compare the dental situation with another population segment sex- and age-matched dates were used. This second population segment lived between the 12th and 18th century and belonged to a lower social class than the patricians from Worb. The comparison of these two groups showed significant differences only in the abrasion pattern. We conclude that the social class did not significantly influence most of the parameters studied here. The different abrasion pattern could be due to different dietary habits.

Alveolar Bone Loss↗