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Biomedical subjects

Z Hirschfeld

Publications and source records attributed to Z Hirschfeld.

At least 19 recordsLinked to original sources
PubMed2000

Analysis of lateral tooth movement during forced orthodontic eruption.

STATEMENT OF PROBLEM: Forced eruption is a prosthodontic procedure that enables the treatment of otherwise problematic restorative conditions. During the vertical orthodontic movement, the root may be moved laterally, affecting the position of a tooth in the arch. PURPOSE: This study quantified the degree of lateral movement possible during the eruptive procedure and addressed the significance of this movement from a theoretical and clinical standpoint. MATERIAL AND METHODS: A patient treatment, which demonstrated the movement in a single direction on the buccolingual axis, was isolated. On the basis of this theoretical model, a clinically relevant model was developed: A "worst-case" situation for each posterior tooth was calculated, from which clinical conclusions may be derived. RESULTS: . In a given extrusion angle of 30 degrees, a lateral movement/shift of 0.58 mm resulted per 1 mm of eruption distance. The lateral movement for every millimeter of eruption and the maximum extrusion angle for each of the maxillary and mandibular posterior teeth were calculated. CONCLUSION: The lateral movement that accompanies the forced eruption procedure may compromise or be used to esthetically enhance prosthodontic treatment.

Bicuspid↗
PubMed1999

The effect of parabens in a mouthwash and incorporated into a sustained release varnish on salivary bacteria.

OBJECTIVES: The purpose of this study was to evaluate the antimicrobial efficacy of parabens, in a mouthwash and in a slow release device, against cariogenic bacteria in the oral cavity. METHODS: Parabens were formulated in a mouthwash or in a topical slow release varnish preparation. In two separate studies, volunteers were asked to use the mouthwash or the slow release varnish applied in a personal night guard device. The levels of mutans streptococci (MS), Lactobacilli (LB) and total cultivated bacteria were measured before and after using the mouthwash or the slow release varnish. RESULTS: The mouthwash containing parabens had a minor and a short-term effect on MS and LB counts in human saliva. The use of slow release varnish containing parabens, applied in a night guard, had a prolonged antibacterial effect on both MS and LB counts. CONCLUSIONS: Parabens in a mouthwash had little effect on oral bacteria counts; however, paraben in the slow release device had a significant and an extended effect in reducing oral bacteria. Although substantial reductions in oral bacterial counts were recorded after the use of parabens in a slow release device, this effect could probably be enhanced by an improved pharmaceutical formulation.

Administration, Topical↗
PubMed1999

The effect of composite resin application and radiation techniques on dye penetration in Class II direct composite resin restorations.

This study examined the effect of the application of resin composite and radiation techniques on dye penetration in class II direct composite resin restorations. For the restorative procedure, the light-cone and the incremental layering techniques were used. The null hypothesis of this experiment was, that both techniques have the same influence on dye penetration. Evaluation of dye penetration in the restoration/tooth interface was performed in 20 extracted premolars and molars. On each tooth, two class II cavities were prepared. The cervical margin of the proximal boxes were located in dentin or in enamel. When the gingival margin of the cavity was located in enamel, a significant lower level of dye penetration of the the test group was found (Wilcoxon rank test, P = 0.0102). This study showed that the application of a transparent cone seems to be more effective than the three increments technique in the mechanical separation of the first composite increment. Transmitting the curing light into the proximal box, seems to have no positive effect on dye penetration in class II direct composite resin restorations.

Bicuspid↗
PubMed1999

A laboratory assessment of enamel hypoplasia of teeth with varying severities of dental fluorosis.

The effect of lifelong exposure to drinking-water containing fluoride on tooth enamel microhardness was investigated. Dental fluorosis of teeth from adult subjects, who lived continuously since birth in areas characterized by the hot climate of India, supplied by drinking-water containing between 0.5 and 8.7 parts/10 F, was estimated by the Dean score. Tooth enamel sections were examined from the enamel surface towards the dentino-enamel junction (DEJ) for microhardness. Separated enamel crowns were pulverized and analysed for fluoride. Regarding the distribution of the fluoride concentrations in the drinking-water, we selected a partition below and above 0.8 parts/10 F as a criterion for comparison between the results. Tooth enamel of humans from Israel living in a drinking-water area containing about 0.5 parts/10 F was also examined. Positive associations were evident between fluoride in drinking-water, fluoride concentrations in the bulk enamel and fluorosis selection. A significantly high inverse relationship was evident between the fluoride concentration of the drinking-water and the subsurface enamel microhardness. In similar fluoride-concentration drinking-water areas of India and Israel the microhardness of the subsurface enamel was less for the Indian teeth. The microhardness of the enamel near the DEJ for the three different water fluoride-concentration areas was not significantly different.

Adult↗
PubMed1998

Forced eruption technique: rationale and clinical report.

This article describes a refined, simplified forced eruption technique, and compared it with previous methods. This simplified method is easy to perform and encourages the use of adjunctive orthodontics in general practice. This relatively uncomplicated, quick, and cost-effective treatment can benefit patients.

Adult↗
PubMed1998

Amalgam alternatives--micro-leakage evaluation of clinical procedures. Part I: direct composite/composite inlay/ceramic inlay.

This study investigated the degree of dye penetration with three different types of tooth-coloured restorations. Twenty-four intact extracted molars were collected. The teeth were immediately stored in water at room temperature. Class II cavity preparations were prepared and restored with three different types of tooth-coloured restorations: A, composite resin in the incremental technique; B, composite inlay technique; and C, ceramic inlay. Specimens were subjected to 700 cycles of thermal stress. They were than immersed in 2% basic fuchsin dye. The teeth were sectioned in three planes before being ranked as to the amount of dye penetration. The highest score obtained on three plano-parallel sections was adopted as the representative value. The three groups were compared using the Kruskal Wallis non-parametric test. Dye penetration was significantly lower at the enamel margins when using the composite inlay system and the incremental technique compared to the ceramic inlay technique. The restorations placed using the composite inlay technique showed less dye penetration than the incremental technique at the dentine margins (P < 0.017).

Coloring Agents↗
PubMed1998

Amalgam alternatives-microleakage evaluation of clinical procedures. Part II: direct/indirect composite inlay systems.

This study investigated the degree of dye penetration of two composite inlay systems with different adhesive and bonding protocol. Forty whole extracted premolars and molars were collected. The teeth were immediately stored in water at room temperature. Class II cavity preparations were prepared and restored both, in the direct and the indirect techniques (Coltene Brilliant) and (Kulzer Estilux posterior CVS). The inlays were cemented with a composite luting cement (ART-Bond) and (Kulzer, Adhesive cement). Specimens were subjected to 750 cycles of thermal stress. They were than immersed in 2% Basic fuchsin dye. The teeth were sectioned in three planes before being ranked as to the amount of dye penetration. The data were analysed by the Wilcoxon's rank test at the 95% confidence level. There was no statistically significant difference between the direct and indirect technique considered separately for each composite inlay material, at the cervical margin location. The fuchsin staining in the occlusal area was limited to the enamel in all groups. By using the composite inlay, the factor of adaptation and bonding of composites to dentine become the significant factor contributing to leakage.

Coloring Agents↗
PubMed1998

In vitro bacterial adherence onto pellicle-coated aesthetic restorative materials.

Adhesion of oral bacteria to teeth and restorative materials plays an important role in the pathogenesis of oral diseases. This study investigated the initial adhesion of Streptococcus mutans to enamel and restorative materials. Three types of composites and two types of glass ionomer cements were used. The specimens were coated with freshly collected human parotid saliva. The salivary coated samples were incubated with cell-free glucosyltransferase, and further incubated with sucrose solution. Finally, the specimens were incubated with 3H-thymidine labelled bacteria. Adhesion of the bacteria to the specimens was measured by scintillation counter. SEM observations were performed on each sample. The results showed no significant differences among the materials and the control. These findings can be explained by the pellicle which coated all the specimens. This biofilm, to which the bacteria were adhered and proved to probably masked existing surface properties of the specimens resulting in similar bacterial adhesion.

Adult↗
PubMed1997

Long-term follow-up of conservative treatment of severely traumatized maxillary incisors.

We present the case of a 26-year-old man who at the age of 9 suffered severe trauma to both maxillary central incisors. The underlying malocclusion was skeletal and classified as dental Class II/1 with severe crowding. Both the maxillary central incisors and the two lower first premolars were extracted and the patient was treated with an edgewise appliance for 2 years. Acceptable occlusal relationships were achieved following orthodontic and adjunctive treatment which consisted of reshaping the maxillary lateral incisors with composite materials and grinding the canines to resemble lateral incisors. A critical evaluation of the esthetic and functional results at the age of 26 years is presented.

Child↗
PubMed1994

Effect of hydrogen peroxide and sodium perborate on the microhardness of human enamel and dentin.

The effect of 30% hydrogen peroxide and a paste of sodium perborate mixed with hydrogen peroxide at different temperatures and time intervals on the microhardness of human enamel and dentin was examined. Intact extracted human teeth were sectioned, embedded in acrylic resin, polished, and divided into four test groups related to surface treatment. The groups were 30% hydrogen peroxide at 37 degrees C, 30% hydrogen peroxide at 50 degrees C in an illuminated chamber, a paste of sodium perborate mixed with hydrogen peroxide at 37 degrees C, and a paste of sodium perborate mixed with hydrogen peroxide at 50 degrees C in an illuminated chamber. Teeth treated with distilled water at either 37 degrees C or 50 degrees C served as controls. The results indicated that treatment with 30% hydrogen peroxide reduced the microhardness of both enamel and dentin. This reduction was statistically significant after 5-min treatment for the dentin and after 15-min treatment for the enamel (p < 0.05). Treatment with sodium perborate mixed with hydrogen peroxide did not alter the microhardness of either the enamel or dentin at the tested temperatures and time intervals. It is therefore suggested that the use of high concentrations of hydrogen peroxide for bleaching purposes should be limited. Sodium perborate appears to be a less damaging bleaching agent.

Borates↗
PubMed1994

Differentiation between major and milder acute mental stress by means of the leukocyte adhesiveness/aggregation test.

Following previous observations that the adhesive state of white blood cells in the peripheral blood increases during stress, we examined 645 volunteers in various conditions of anticipatory anxiety. The volunteer subjects included 465 controls in whom stress was related solely to impending venipuncture, 149 persons under moderate stress (students before delivering a graded lecture, patients before dental treatment, etc), as well as 31 individuals under major stress (eg, before induction of anesthesia in the operating room). The respective values of aggregated leukocytes in the peripheral blood were 5.2 +/- 3.8, 6 +/- 4.2, and 19.3 +/- 9.3% of aggregated cells, with a significant difference (p < .0001) between the third and the other two groups. In both discriminant analysis and multiple regression, the leukocyte adhesiveness/aggregation test (LAAT) was shown to be superior to the white blood cell count for the detection of major stress. The LAAT had a sensitivity of 0.8, compared with only 0.35 for leukocyte count for that purpose. We concluded that the LAAT could be a powerful tool for the diagnosis of major acute mental stress and for discrimination between conditions causing major stress and those conditions that are less stressful.

Adolescent↗
PubMed1992

Marginal leakage of class II glass ionomer-composite resin restorations: an in vitro study.

This in vitro study assessed the sealing properties of two metal-reinforced glass ionomer cements, used as "extended bases" in glass ionomer-composite resin restorations. Two class II cavities were prepared in the proximal surfaces of 30 molars. The gingival margin of one was prepared in enamel and the other in cementum/dentin. Fifteen teeth (30 cavities) were restored with Ketac Silver material used as an extended base (group A). In the remaining 15 teeth (30 cavities), the extended base was in Miracle Mix material (group B). All occlusal surfaces were restored with Estilux Posterior Material. The restored teeth were thermocycled, immersed in fuchsin, washed in water, embedded, sectioned, and examined under a dissecting microscope. All restorations with margins in cementum/dentin of group A (Ketac Silver) leaked. No microleakage occurred in 12 of the 30 restorations with margins in cementum/dentin of group B (Miracle Mix). In addition, severe microleakage was present in 24 teeth of group A, as opposed to three in group B. It was concluded that the sealing properties of Miracle Mix material are superior to those of Ketac Silver material, in vitro.

Cermet Cements↗
PubMed1992

One-year clinical evaluation of an anterior composite resin.

An anterior composite resin was evaluated in a clinical study of 93 Class III and Class IV restorations placed in patients aged 12 to 50 years. The restorations were evaluated at baseline, 6 months, and 1 year. Sixty-four (79%) of the 81 restorations examined at the 1-year recall were unchanged. Marginal discoloration and changes in surface appearance and marginal adaptation accounted for most of the changes. All changes appeared in patients younger than 14 years, which may indicate that the patients had problems in oral hygiene. Replicas of randomly selected restorations showed smooth surfaces and well-sealed margins with a smooth transition from restoration to enamel. Some restorations showed marginal breakdown and a pitted irregular surface.

Adolescent↗
PubMed1991

Esthetic repair of porcelain in a complete-mouth reconstruction: a case report.

This paper presents a relatively simple method of repairing a large porcelain fracture in a porcelain-fused-to-metal crown that is part of a multi-unit fixed partial denture. The technique involves fitting a "modified" porcelain-fused-to-metal crown over the original damaged crown following some preparation of the original crown. This technique is of special value when a permanently cemented multi-unit restoration is involved, eliminating the need to replace the entire restoration and providing a durable esthetic result.

Crowns↗
PubMed1991

Marginal leakage around V-shaped cavities restored with glass-ionomer cements: an in vitro study.

The object of this investigation was to assess the degree of marginal leakage around V-shaped cervical glass-ionomer cement restorations and compare it to that around composite resin restorations. Three different glass-ionomer cements and one composite resin control were assessed by means of dye penetration. Severe microleakage at the occlusal margins was found in 70% of the glass-ionomer cement restorations, but in only 10% of the composite resin restorations. A considerable amount of dye penetration was observed at the cervical margins of all restorations, including the controls. None of the glass-ionomer cements tested showed superiority in preventing marginal leakage occlusally or gingivally.

Bicuspid↗