Dentin micro-architecture using harmonic generation microscopy.

OBJECTIVES: We present a novel way to create high-resolution three-dimensional images of tooth dentin by harmonic generation scanning laser microscopy. METHODS: The images were taken using a pulsed infrared laser. Three-dimensional reconstruction enables the visualization of individual tubules and the collagen fibrils mesh around them with an optical resolution of approximately 1 microm. RESULTS: The images show micro-morphological details of the dentinal tubules as well as the collagen fibrils at a depth of up to about 200 microm. The data show that while collagen fibrils are organized in planes perpendicular to the tubules, close to the dentin enamel junction they lie also along the long axis of the tubules. CONCLUSIONS: The unique 3D information opens the opportunity to study the collagen fibril arrangement in relation to the tubule orientation within the dentin matrix, and may be applied to study the micro-morphology of normal versus altered dentin.

The effect of an intermediate layer of flowable composite resin on microleakage in packable composite restorations.

OBJECTIVES: The aim of the present study was to evaluate the effect of a thin layer of flowable composite on microleakage in Class II direct packable composite resin restorations on young permanent teeth in vitro. METHODS: Twenty sound human premolars and molars extracted for orthodontic reasons were selected for this study. The teeth were randomly assigned into two groups of 10 teeth each (groups A and B). Class II cavities were prepared as uniformly as possible in the mesial and distal aspects of each tooth. The gingival margin extended apically approximately 0.5 mm beyond the cemento-enamel junction, in the dentin. Cavities in group A were restored with packable composite and Alert/Flow-it flowable composite, while groups B cavities were restored with Pyramid/Aeliteflo. The control cavities in groups A1 and B1 were restored with only packable composite. The teeth were immersed in 2% methylene blue solution for 24 h to allow dye penetration into possible existing gaps between the tooth substance and the restorative material. All teeth were subjected to thermocycling. RESULTS: The dye penetration ranged between 6.6 and 7.2 mm. No significant difference was found between the control and the experimental groups. CONCLUSION: The use of flowable composite resin as intermediate material does not reduce microleakage.

Evaluation of cetylpyridinium chloride for infection control in storage solution.

Storage solution is used in in vitro experimental studies to prevent dehydration of teeth collected immediately after extraction and to prevent bacterial and fungal growth in the storage media. The chemical nature of the storing agent may affect the tooth structure and material properties at the tested interface. The aim of this study was to evaluate the use of 0.1% cetylpyridinium chloride (CPC) as a new storage solution and to assess the possible effect of 0.1% thymol on microleakage and bond strength. Forty extracted human teeth were collected from 10 different dental clinics. Immediately after extraction, the teeth were randomly divided and immersed in four different storage solutions. Two test solutions of 0.1% CPC (group C) and 0.1% thymol (group T) were compared with phosphate-buffered saline (Group S - positive control) and to 3% H2O2 (group H - negative control). Bond strength test and dye penetration evaluation were then carried out. The findings suggest that the use of 0.1% CPC as storage solution does not affect bond strength to enamel. However, it may increase dye penetration at the cervical margin. The effect of 0.1% thymol on shear bond strength and dye penetration is similar to the effect of phosphate-buffered saline.

[Carisolv, a change in the perception of caries treatment--a chemo-mechanical removal of caries].

This paper reviews the chemo-mechanical method (Carisolv) for caries removal. The mechanism of action and some treatment choices are described. Modern dentistry aims to preserve tooth structure by minimal invasive procedures. Chemo-mechanical removal of caries is a new method with the advantage of selective removal of severely demineralized dentin. This enhances the caries diagnostic ability of the clinician. Ensuring chair side caries diagnosis and removal, based on a biological principle, helps to preserve as much healthy tissue as possible. This method is most comfortable for the patient. On the other hand treatment time is prolonged. In most cases, the method has to be used in combination with a conventional bur. Caries lesions in which removal of enamel or a restoration is needed cannot be treated exclusively by the chemo-mechanical method. However, the chemo-mechanical caries treatment can be used as the first choice of treatment in specific cases in the prosthodontic and pediatric field.

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.

Use of female controlled microbicidal products for HIV risk reduction.

Many over-the-counter microbicidal contraceptive methods reduce the risk of acquiring sexually transmitted diseases. This pilot project compared the use of female controlled barrier methods in an extremely high-risk population of low-income drug abusing women following an intervention designed to promote HIV risk reduction and barrier use. An HIV transmission risk reduction interactive intervention emphasizing self-esteem, assertiveness and sexual negotiation was offered to 41 drug dependent women. Participants were randomly assigned to one of two conditions, a male and female condom condition or a male and female condom plus N-9 products (vaginal suppositories, film, gel) condition. Results from the three-month follow-up period suggest that there may be a synergistic effect of availability of multiple protective methods on the overall rate of protective behaviours. The use of the male condom for penile/vaginal sex increased from 19% at study entry to 27% during the three-month follow-up period. The total protected sexual episode rate, calculated to include use of the other protective barriers distributed, was 60%. Thus, the condom use rate was not found to decrease because of the availability of alternative methods of protection. Future research should address the use of microbicidal products to empower women to prevent STD/HIV transmission.

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.

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.

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).

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.