Microleakage of Class II composite restorations.

PURPOSES: (1) To evaluate the in vitro sealing ability of several Class II resin restorations whose gingival extension of the proximal margin was apical to the cemento-enamel junction and in dentin and (2) to determine the effect of thermocycling on leakage into the resin-tooth interface. MATERIALS AND METHODS: Mesio-occlusal and distoocclusal preparations were made in extracted human molars. The gingival floor of the proximal box, was placed 1.0mm apical to the CEJ, and was prepared to a width of 1.5mm from the cavosurface margin to the axial wall. The teeth were restored with one of seven restorations (Z100 control, Z100, Wave, F2000, Surefil, Z100 and Vitrebond Sandwich A, Z100 and Vitrebond Sandwich B) using multiple incremental placement and materials. Following storage, half the samples were thermocycled. All 70 samples were stained using silver nitrate. The entire resin restoration was then removed from the proximal box ,and starting at the cavosurface margin the gingival floor was divided into three zones of 0.5 mm each and analyzed for dye penetration, using a novel technique which utilized the aid of computer imaging software and assessed both quantitatively and qualitatively. RESULTS: There was no statistical difference in leakage for all groups in Zone 1. For Zones 2 and 3, the groups utilizing glass-ionomer liner on the cavosurface margin had significantly less microleakage (P>0.05). Although the compomer/hybrid combination had low leakage values on average, the wide range of values led to unpredictable results. The flowable/hybrid combination and the packable composite performed less favorably. CLINICAL SIGNIFICANCE: This study demonstrated the difficulty in sealing a proximal dentin margin. However, the glass-ionomer/hybrid restorative techniques is the most likely to give successful clinical results.

Post retention and post/core shear bond strength of four post systems.

As clinicians we continue to search for a post system which will give us maximum retention while maximizing resistance to root fracture. The introduction of several new post systems, with claims of high retentive and resistance to root fracture values, require that independent studies be performed to evaluate these claims. This study tested the tensile and shear dislodgment forces of four post designs that were luted into roots 10 mm apical of the CEJ. The Para Post Plus (P1) is a parallel-sided, passive design; the Para Post XT (P2) is a combination active/passive design; the Flexi-Post (F1) and the Flexi-Flange (F2) are active post designs. All systems tested were stainless steel. This study compared the test results of the four post designs for tensile and shear dislodgment. All mounted samples were loaded in tension until failure occurred. The tensile load was applied parallel to the long axis of the root, while the shear load was applied at 450 to the long axis of the root. The Flexi-Post (F1) was significantly different from the other three in the tensile test, however, the Para Post XT (P2) was significantly different to the other three in the shear test and had a better probability for survival in the Kaplan-Meier survival function test. Based on the results of this study, our recommendation is for the Para Post XT (P2).

Interactions between smokers and non-smokers in public places: a qualitative study.

Few studies have employed a qualitative approach to better understand how both smokers and non-smokers experience and make sense of no-smoking restrictions in their daily lives. We describe qualitative research involving an examination of self-reported interpersonal interactions between smokers and non-smokers in public places regarding exposure to environmental tobacco smoke (ETS). Five focus group discussions and twenty individual in-depth interviews were conducted with smokers and non-smokers in the Metropolitan Toronto region as a complement to a quantitative survey of the adult population of Ontario. Strategies used by non-smokers in responding to ETS exposures included verbal confrontations, non-verbal cues, use of a third party, and moving away. The perceived consequences of such actions, as described by both smokers and non-smokers, are discussed, together with implications for tobacco control policy and practice.

Vital pulp capping: a worthwhile procedure.

Despite the progress made in the field of pulp biology, the technique and philosophy of direct vital pulp capping remains a controversial subject. Clinicians are well aware of the immediate and long-term success rates after root canal therapy, but are less certain of the success of vital pulp capping. Researchers have demonstrated that exposed pulps will heal and form reparative dentin. It is realized now that the variable prognosis of vital pulp capping is predominately a restorative issue. The factors that can produce a successful vital pulp cap are discussed in conjunction with two popular techniques.

Factors affecting retention of post systems: a literature review.

STATEMENT OF PROBLEM: An extensive review of the published literature has revealed a wide divergence of opinion regarding the suitability of different post systems for endodontically treated teeth. As a result, the dentist has no clear guidelines concerning the selection of suitable post systems that will provide adequate retention while minimizing subsequent root fracture. PURPOSE: This study formulated, through the literature search, a set of guidelines to assist the dentist in selecting an endodontic post system that would optimize retention while limiting root fracture. RESULTS: For most clinical situations, the literature indicates that a passive parallel-sided post will, in the hands of the average practitioner, allow the dentist to successfully restore most endodontically treated teeth.

Retention and shear bond strength of two post systems.

The purpose of this study was to compare the retention and shear strength of teeth restored with the Para Plus post (P) and the C post (C1 and C2) systems. Twenty-four P, C1, and C2 posts each were placed 7 mm into recently extracted and endodontically treated maxillary anterior roots and luted with Ketac-Cem and Bis-Core respectively. In addition, 13 samples of each post type had a Bis-Core composite core placed. The tensile retention strength of the post and the shear strength of the post and core restorations when the core was loaded buccolingually at 45 degrees to the roots' long axis were determined at a strain rate of 1.3 mm/min. The C2 posts required significantly more tensile force (P < 0.0001) to remove them than the P or C1 posts. The shear strength of the post/core restorations was not significantly different (P < 0.04). The C1 restorations had 12 root fractures, the C2 restorations had 11 root fractures, and the P samples had six root fractures. It was concluded that the lack of stiffness of the C posts adversely affected the success of these restorations.

Management of accidental and iatrogenic injuries to the dentition.

This article discusses the restoration of teeth with extensive fractures extending beyond the attachment of the periodontal ligament, as well as the treatment of iatrogenic perforations observed during post space preparation. Various treatment procedures and their limitations are described, based on the authors' many years of clinical experience.

Are posts mandatory for the restoration of endodontically treated teeth?

In this era of fiscal and professional accountability, variations in the utilization of posts to improve the retention of crowns or other restorations on endodontically treated teeth are no longer acceptable. This practice ignores not only the potential for root perforations during post space preparations, but also the adhesive properties of modern resin-based materials. Since the retention of restorations hinges on many other factors, the placement of posts does not necessarily assure service quality and may even lead to deleterious changes. The need to reappraise the utilization of posts in the restoration of endodontically treated teeth cannot be overstated.

Cantilever fixed partial denture--a literature review.

In light of the increasing demand for fixed prosthetics by today's patients, the author felt the time was right for a review of an area of fixed prosthetics that is neither well understood nor well accepted. The cantilever fixed partial denture (FPD) requires more time to treatment plan and place than other comparable fixed prosthetics. However, if the necessary criteria are met, the final results can be very rewarding for the practitioner and the patient from both an esthetic and a functional standpoint. This article discusses various factors that impact on the practitioner's ability to place a cantilever FPD with the expectation of long-term success, as well as other related areas of treatment planning.

Eyeglasses and children's schemata.

The role of framed eyeglasses in children's person schemata was examined. American first graders (35 girls, 36 boys), rated by their teachers as low, medium, or high in cognitive development, judged peers photographed with and without glasses for physical attractiveness, school performance, conduct, sociability, and sociometric choice. There was a general same-sex bias in the children's ratings. The stimulus persons tended to be rated lower in attractiveness (especially if they were girls), school performance, and conduct when they were wearing glasses than when they were not wearing glasses. Glasses negatively influenced sociometric choice, but only for the most cognitively developed children. These results indicated that adults' stereotypes about people who wear glasses eventually become part of children's person schemata.

The effect of a phenylalanine and tyrosine restricted diet on elemental balance studies and plasma aminograms of patients with disseminated malignant melanoma.

Previous studies indicate dietary phenylalanine and tyrosine restriction may be of value in managing advanced cancer patients. To further evaluate this approach, we performed a 60-day study in which four patients with advanced malignant melanoma received formula diets via nasogastric tube containing only 8 mg total phenylalanine and tyrosine per kg lean body mass per day. Two of three patients completing elemental balance studies were in negative nitrogen, potassium, and phosphorus balance, suggesting an essential nutrient deficiency. Three patients tolerated the diet well, but one was non-compliant. Although no serious toxicity developed, serum albumin, total iron binding capacity and cholesterol significantly decreased (p less than 0.01) in the three complaint patients. Fasting plasma phenylalanine and tyrosine values did not significantly change during the study, but two-hour postprandial plasma phenylalanine and tyrosine concentrations fell below normal and were significantly lower than preprandial levels (p less than 0.01). There were no tumor responses.