Handling characteristics of resin composites in posterior teeth

In the last 10 years, tremendous improvements in strength and shade selection for resin composites have been achieved. Also, a new generation of enamel-dentin bonding systems has been developed, and patient expectations of esthetic treatment have risen. Several techniques are available for restoring posterior teeth. When a caries lesion is limited, a direct esthetic restoration is indicated. Essential elements for obtaining good, long-term clinical results for direct esthetic restorations of posterior teeth are: (1) cavity preparation; (2) knowledge of the characteristics of the three dental substrates; (3) rubber dam use and matrix and wedge placement; (4) correct use of the enamel-dentin bonding system; (5) proper selection of the resin composite material; (6) use of the multilayering technique; (7) finishing and polishing procedures; and (8) maintenance of the restoration.     

Current status of luting agents for fixed prosthodontics

STATEMENT OF THE PROBLEM: The long-term clinical outcome of fixed prosthodontic treatment depends, in part, on the use of adhesives that can provide an impervious seal between the restoration and the tooth. There are several types of available luting agents, each possessing unique properties and handling characteristics. No one product is ideal for every type of restoration. PURPOSE: The purpose of this article is to review available dental luting agents, discuss improvements and drawbacks in newly formulated adhesives, and present the indications for their use. RESULTS: Each cement type is physically and chemically unique. A single adhesive will not suffice in modern day clinical practice.     

Effect of restoration composition, shade, and thickness on the cure of a photoactivated resin cement

PURPOSE: This study investigates the effect of selected properties of a restorative material (type, shade, and thickness) on the cure of a photoactivated resin cement. MATERIALS AND METHODS: Disks of ceramic and resin-based restorative materials of two extreme shades were made to provide thicknesses of 0.5 to 3.0 mm in 0.5-mm intervals. Light transmission was measured through various thicknesses and shades of each restorative material type. The effect of light transmission, as influenced by restorative material type, shade, and thickness on resin cement cure was also determined. RESULTS: Thickness and shade of restorative material had the greatest influence on light transmission. For simulated restoration thicknesses 1.5 mm and greater, Dicor (Dentsply International Inc, York, PA) had greater transmission of light than the other materials, regardless of shade. At equal restorative material thickness, light transmission was similar for identical shades of the other three materials. Restoration shade and thickness also had the greatest influence on resin cement cure. Material type, although significant, had only a minor influence. At thicknesses of 1 to 2 mm, Dicor consistently yielded greater resin cement cure values than any other material tested. CONCLUSIONS: When considering the ability of restorative materials to transmit light for curing of photo-activated resin cements, the thickness of the restoration and its shade are much more influential than the choice of restorative material. Dicor provides greater light transmission that results in the ability to photobond restorations of greater thicknesses than the other materials. For restorations greater than 1 mm in thickness, a dual cure or chemical cure resin cement should be used to provide maximal cement properties.     

The treatment of class III maxillary furcations using a resin-ionomer. A case report

This case report uses a resin-ionomer restoration as a barrier in the treatment of a Class III furcation defect. There was a reduction in tooth mobility and plaque count, no bleeding on probing, and a decrease in probing depth with the use of the resin ionomer. The study offers another treatment option in the treatment of a seemingly hopeless maxillary molar.     

Prevalence and depth of artificial caries-like lesions adjacent to cavities prepared in roots and restored with a glass ionomer or a dentin-bonded composite material

One potential advantage of glass-ionomer materials for the treatment of root caries is their ability to release fluoride and so resist cariogenic attack. A commercially available composite material has also been reported to release fluoride which reduced caries lesions in the tooth tissue adjacent to it. The aim of this study was to assess the effectiveness of a conventional glass-ionomer restoration compared with a dentin-bonded, fluoride-releasing, composite restoration when exposed to a microbial artificial caries system. Artificial caries-like lesions produced in relation to the restorations were examined and classified either as outer (surface) lesions or as wall lesions. A split-unit experimental design allowed for within-tooth comparisons of the 2 experimental restorations at different sites on the root surface. These were either totally within the root surface or positioned at the amelo-cemental junction. Outer lesion depths were significantly (p < 0.001) shallower at all sites adjacent to the glass ionomer when compared with the composite restorations. Wall lesions were significantly (p < 0.01) more prevalent adjacent to the composite material. In addition, the cavity margin position significantly (p < 0.05) affected the incidence of wall lesions, particularly in the composite group. In conclusion, glass ionomer was successful in reducing the caries-like lesion production in the adjacent root surface. This resulted from improved marginal integrity and fluoride release from this material when compared with the composite bonding system used.     

Crown lengthening: a clinical review

The use of crown lengthening surgery as an adjunct to restorative therapy was first suggested by Rosen and Gitnick. This technique is designed to increase the clinical crown heights of teeth requiring restoration following extensive wear through attrition, abrasion and erosion. This loss of tooth tissue and resulting clinical crown height may be localized to a few teeth or affect the entire dentition. This clinical problem is reflected by the increasing number of reports of treatment of the worn dentition.     

Two-implant-supported single molar replacement: interdental space requirements and comparison to alternative options

Posterior single-tooth implant restorations are subjected to an increased risk of bending overload. A high incidence of implant fracture has been reported when using a single standard 3.75-mm-diameter implant to support a molar restoration. The purpose of this article is to demonstrate the clinical feasibility of placing two implants to support a molar restoration and to compare this treatment option to the use of a single standard implant or a wide-diameter implant. Two osseointegrated dental implants used to support a molar restoration in interdental spaces as small as 10 mm is shown to be effective and predictable in 60 restorations over the past 7 years. The use of two implants provides more surface area for osseointegration and spreads the occlusal loading forces out over a wider area, reducing the potential bending forces that would otherwise exist in a single-implant molar restoration.     

Use of provisional restorations to enhance soft-tissue contours for implant restorations

The objective of restoring missing teeth with implant-supported restorations should not merely be achieving osseointegration with an implant and a biomechanically sound restoration. The objective must be the esthetic and functional restoration of the missing teeth. To achieve this, proper treatment planning is critical. Precise implant placement and delicate soft-tissue manipulation during surgery will allow the restorative dentist to enhance the peri-implant soft-tissue contours with the use of provisional restorations. Empirically, it seems that the earlier the provisional restoration is delivered in the treatment process the more ideal the esthetics. Several methods of using provisional restorations to enhance soft-tissue contours are presented. The concept of immediately delivering provisional restorations on placement of an implant is discussed.     

Usefulness of enhanced insulin secretion during an oral glucose tolerance test as a predictor of restenosis after direct percutaneous transluminal coronary angioplasty during acute myocardial infarction in patients without diabetes mellitus

Extensive prosthodontic treatment often requires fabrication of long-term provisional restorations. Numerous materials and techniques have been described for prolonged insertion of interim restorations. This article describes a procedure for fabrication of long-term reinforced heat-processed provisional restorations based on a diagnostic wax-up. Reinforced heat-processed provisional restorations reduced flexure, which minimizes progressive loss of cement and diminished the possibility of recurrent decay. Occlusal stability and vertical dimension were maintained because of greater wear resistance. Occlusion, tooth contours, and pontic design developed in the provisional restoration were duplicated in the definitive restoration. The use of a matrix from a diagnostic wax-up facilitated fabrication of the prosthesis, and made the procedure less time-consuming and more predictable.     

The structure of tobacco ringspot virus: a link in the evolution of icosahedral capsids in the picornavirus superfamily

Electronic portal imaging devices use the high energy treatment beam to project the body interior of the patient during radiation onto a fluorescent screen that is scanned by a camera. Because of the imaging physics, the unprocessed images of very poor quality, but they are the only available information during treatment for observation of the patient's organs. This paper presents an approach that combines an associative restoration algorithm with a fuzzy image enhancement technique. By fusion of the electronic portal image (EPI) with a pre-treatment captured simulator image (SI) a higher image quality than by conventional techniques is achieved.     

Particulate bioglass compared with hydroxyapatite as a bone graft substitute

Bioactive ceramics, notably hydroxyapatite, have been used clinically in various situations in which bone augmentation and restoration are required. Particulate material has been used either alone or in conjunction with freeze dried or autologous bone, with variable clinical success. In this study a bioactive glass, 45S5 Bioglass, has been compared with hydroxyapatite in an animal model to discover whether the 2 major disadvantages of hydroxyapatite may be overcome. These are the difficulty of placing and retaining the particulate in the defect and the length of time needed before full bony restoration is achieved. Bioglass is shown to be easy to manipulate and hemostatic and allows full restoration of bone in 2 weeks, rather than the 12 weeks needed for the particulate hydroxyapatite to produce a comparable response. The Bioglass particulate is used up in the process, and any problems that may be associated with the production of a composite of bone and biomaterial are avoided in the fully restored bone. In any procedure that requires bony augmentation, this rapid response to Bioglass is expected to provide a clinical advantage.     

Selection of restorative materials, reasons for replacement, and longevity of restorations in Florida

The purpose of the present study was to obtain information relating to the types of restorative materials used, the main reason for replacement of restorations, and the age of failed restorations. Dentists in general dental practice in Florida were invited to record details from their own work pertaining to restorations. The diagnostic criteria were described and coded. The clinicians were not calibrated in the use of the criteria but they could call in for further explanation if needed. The 27 clinicians involved placed 2,035 restorations of which 53% were replacements of failed restorations. The increased use of resin based restorative material was clearly evident including posterior composites. The clinical diagnosis secondary caries was the most common reason for replacement of amalgam (56%) and composite (59%) restorations. Only discoloration showed a statistically significant difference in the reason for replacement of the two types of materials. The median age of the replaced amalgam restoration was 15 years and that of composite restoration was 8 years.     

Therapeutic technique: treatment of a borderline adolescent girl

This paper is a case presentation of an acting-out borderline adolescent girl, who had been exposed to three previous attempts at treatment. The clinical material gives evidence of diagnostic and dynamic understanding of the borderline syndrome. The treatment technique--confrontation--is elucidated with examples of its use.     

农药污染场地治理技术体系与安全利用模式及方案

农药污染场地具有污染成分复杂、异味问题突出、修复治理难度大、安全利用风险高的特点,是当前亟待解决的重点土壤环境问题。“十三五”期间,我国农药污染场地治理技术趋近成熟,安全利用模式初步形成。在总结归纳农药场地治理技术和成功案例的基础上,针对污染物类型和土质特性,构建了农药污染场地治理技术体系,提出了基于用地规划、敏感受体和污染物类型的安全利用模式与方案,以期指导农药场地污染风险管控与治理修复工作,为农药污染场地安全利用和科学管理提供依据。     

修复热处理方法及技术内涵分析

具体分析了修复热处理的技术内涵及应用途径．并对修复热处理的目的及内容进行了概述;重点讨论了材料失效机理和作为修复热处理基本原理的材料自愈合和自修复机理,并对修复热处理的基本方法和应用进行了简单介绍。     

Potential role of the peroxynitrate-poly(ADP-ribose) synthetase pathway in a rat model of severe hemorrhagic shock

PURPOSE: The purpose of this study was to assess the performance of sealants placed by senior dental students as part of a comprehensive dental care program that included periodic patient recall. METHODS: The dental records of 100 patients ranging in age from 6 to 13 years were selected for review to determine the treatments provided for first permanent molars over time. Criteria for inclusion were: 1) at least five documented recall examinations and 2) all four first permanent molars had to have been treated with an occlusal pit and fissure sealant. The data collected included: 1) the age of the patient at the time of initial sealant placement; 2) the subsequent treatment provided to the first permanent molars, including retreatment with sealant or restoration and the date the services were provided; 3) the last date of follow-up examination in the pediatric dental program. RESULTS: A total of 400 molars were followed for an average of 54 months. Fifty-two percent of all molars received no further treatment after initial placement of sealant. Approximately 35% received retreatment with sealant only. The total number of molars receiving sealant material only was 343 (86%). The total number of teeth that were judged to require restoration was 57 (14%). No relationship was noted between the patient's age at placement of the occlusal sealant and sealant performance. CONCLUSION: In a dental school clinic, occlusal sealants were effective at preventing caries in a comprehensive care program that included periodic recall.     

Recent advances in the surgical treatment of faecal incontinence

STATEMENT OF PROBLEM: Even though assessments of borderline restorative items in terms of accuracy and interexaminer variation have been reported, no attempt has been made to simultaneously evaluate diagnostic and treatment planning decision using objective normative standards. PURPOSE: This study established the accuracy of caries presence assessment as compared with gold standards, interexaminer agreement in assessment of caries presence and restorative needs, and influences of perceived caries status and restoration quality on treatment planning in borderline restorative situations. MATERIALS AND METHODS: Fifteen senior dental students in Mexico City (66% women; mean age 23.2 years) evaluated predetermined areas in 109 restored and unrestored posterior teeth in an in vitro model. Teeth were subsequently assessed for restoration quality and the presence of enamel and dentinal caries by use of histologic and specific dye techniques. Student's t test, Cohen's kappa, and Pearson's correlation analyses were used to analyze the data. RESULTS: There were significant caries misdiagnoses and substantial overtreatment proposed. In a few instances, teeth were left untreated, but usually they were programmed for restoration. Interexaminer agreement varied markedly and was not high. However, performance while correctly detecting lesions was better than in treatment planning. CONCLUSION: There was a high correlation between a diagnosis of caries and restorative treatment in unrestored teeth; the correlation was lower for restored teeth, although they were allocated to restorative treatment more often. This difference hinged on perceived quality of the restoration, an important factor in the frequency of proposed re-restoration.     

Periodontal and dental considerations in clinical crown extension: a rational basis for treatment

When the clinical crowns of teeth are dimensionally inadequate, esthetically and biologically acceptable restoration of these dental units is difficult. Often an acceptable restoration cannot be accomplished without first surgically increasing the length of the existing clinical crowns; therefore, successful management requires an understanding of both the dental and periodontal parameters of treatment. This report provides further insight into this interdependence by examining the effects of tooth form on the periodontal morphology and surgical treatment, while relating them to requirements for esthetically and biologically acceptable full-coverage dental restorations. This report also explains the role that restoration margin location and emergence profile play in the maintenance of periodontal and dental symbiosis. The effects of violation of the supracrestal gingivae by improper full-coverage restorations is also illustrated.     

The mirror as a fixation aid for the fundus camera (author''s transl)

Self-emasculation is the end result of an unusual psychiatric disorder, which initially requires surgical treatment. Only 51 cases have been reported in the English literature since 1900. No previous attempt to preserve testicular androgen function by reimplantation or grafting has been reported. We describe an unsuccessful attempt to graft the testicles in subcutaneous thigh pockets. Microscopically, the biopsied autografts showed no viable interstitial or germinal testicular tissue. The objectives of the treatment of self-emasculation injury are restoration of anatomical and functional continuity of the urethra as a urinary channel, preservation of the capacity for sustained penile erection, preservation of testicular androgen activity, prompt psychiatric evaluation and treatment of the underlying illness, and restoration of the normal appearance of the scrotum.