Critical Appraisal

Bonding of resin to dentin involves three basic steps: etching, priming, and bonding. Many of the simplified systems currently on the market have combined priming and bonding steps, forming the so-called one-bottle adhesives. Another approach to simplification is combining the etching and priming steps to formulate self-etching primers. The development of self-etching primers has taken place mainly in Japan. This review analyzes several recent publications on this interesting aspect of resin bonding to enamel and dentin.     

Critical Appraisal

Many dentists still view zinc phosphate as the "gold standard" for luting cast and porcelain-fused-to-metal restorations. Introduced in 1879, zinc phosphate cement has withstood the test of time and gained a reputation for reliability despite its nonadhesive qualities and association with postcementation sensitivity when handled improperly. Hewer classes of luting cements have been introduced, including polycarboxylate, glass ionomer, resin-reinforced (resin-modified) glass ionomer, and resin composite. Several of these materials have advantages over zinc phosphate, including adhesion to alloys and tooth structure, fluoride release, and improved physical properties. Conversely, they also exhibit some disadvantages, such as higher cost, complex handling requirements, and adhesive qualities that can make retrieval of castings impossible. This "Critical Appraisal" reviews recent articles dealing with newer luting cements in an effort to give readers some assistance in their selection and use.
Two publications address the effect of handling and manipulation variables on the physical properties of various cements. Another in vitro investigation highlights the margin sealing effect of resin-modified glass ionomer composite (GIC) with and without saliva contamination. Finally, a large retrospective study reports clinical outcomes of anterior and posterior alumina core all-ceramic crowns luted with a resin-modified GIC. The significance of each publication is discussed below.     

Critical Appraisal

Bonding of resin to dentin involves three basic steps: etching, priming, and bonding. Many of the simplified systems currently on the market have combined priming and bonding steps, forming the so-called one-bottle adhesives. Another approach to simplification is combining the etching and priming steps to formulate self-etching primers. The development of self-etching primers has taken place mainly in Japan. This review analyzes several recent publications on this interesting aspect of resin bonding to enamel and dentin.     

Critical Appraisal

Surprisingly, many clinicians fail to realize that the quality of their direct, tooth-colored restorations is directly related to the extent to which the polymer is cured, and that the extent of cure relies heavily on the quality of photoinitiating systems. In this second of two Critical Appraisal articles, attention is drawn to issues related to polymerization shrinkage and preparation design, variation in light intensity output, and direction of composite shrinkage. Many references presented are classic in the field, having been published over a decade ago, but these are still relevant to everyday clinical dentistry.     

Critical Appraisal

The topic of visible light-curing has become controversial in recent years. Strong interest from dentists and manufacturers as well as from researchers and scientists has brought about the publication of numerous articles on the topic. In view of the great quantity of frequently conflicting information, it is important to accurately analyze and interpret the results and the conclusions of these studies. Because multiple factors can influence the resulting polymerization process, it might still be too soon to favor one of the new curing techniques rather than the conventional one that has been used for many years. By trying to understand the complex phenomenon of composite polymerization, dentists will be able to make decisions based on scientific proofs rather than on momentary trends. To fulfill this goal, this first of two critical appraisals is devoted to the effect of different curing techniques on the properties and characteristics of the cured composite. The second appraisal, to appear in a subsequent issue of the Journal of Esthetic and Restorative Dentistry, will address the issue of polymerization contraction stress effects on the adhesive bond between enamel or dentin and the composite restoration.     

Critical Appraisal

Several manufacturers have introduced "condensable" or, more accurately, "packable" composites for restoration of posterior teeth. Typically, the differences between these and more traditional composites are an increase in stiffness and a reduction in stickiness. However, some manufacturers have made claims of improved physical properties for their materials. This review evaluates the published laboratory research on packable composites.     

Critical Appraisal

The use of all-ceramic fixed partial dentures is still controversial, although materials for ceramic frameworks have been introduced into the market and new materials and techniques and technologies for their fabrication are constantly evolving. In the quest to provide scientific data evaluating these new systems and to provide clinicians with guidelines for their use, in vitro studies followed by clinical ones have been and are currently performed. Although in vitro strength studies provide both clinicians and researchers with useful information for selecting ceramic materials and techniques for further research, they might not directly predict or reflect clinical performance. To enhance their clinical relevance, in vitro studies should better mimic oral conditions, such as cyclic loading and contact stresses, tooth mobility, temperature changes, and chemically assisted degradation. Such in vitro studies simulating oral conditions will provide clinically relevant information. However, clinicians must rely on the results of properly designed clinical studies to determine the efficacy of all-ceramic fixed partial dentures before prescribing such treatment to their patients. This "Critical Appraisal" continues a discussion of the in vitro studies. Part III will discuss the clinical studies on the clinical performance of all-ceramic fixed partial dentures.     

Critical Appraisal: At-home bleaching: pulpal effects and tooth sensitivity issues, part I

The most common side effect of at-home bleaching is transient tooth sensitivity. Despite its high frequency, this phenomenon is not well understood. This two-part Critical Appraisal presents a summary and analysis of several articles on tooth sensitivity issues with at-home bleaching. The first installment reviews articles that focus on the incidence of sensitivity, long-term effects of bleaching, and related pulpal concerns. The second installment also will cover pulpal concerns, as well as the prevention of sensitivity during at-home whitening treatments.     

Relevant Anatomic and Biomechanical Studies for Implant Possibilities on the Atrophic Maxilla: Critical Appraisal and Literature Review

Purpose: The purpose of this review was to highlight anatomic and biomechanical aspects of atrophic maxillae for implant possibilities. Materials and Methods: A MEDLINE electronic search of the years 1966 to 2009 was conducted with the keywords “atrophic,”“resorbed,”“edentulous,” and “maxilla.” Results: Twenty papers presented the following findings: (1) previous use of a removable prosthesis is a risk factor for resorption, with flabby tissues related to the severity of resorption; (2) implants in the reconstructed maxilla (≤5 mm) and supporting overdentures had a higher risk for bone loss based on the worse periimplant soft‐tissue health observed; (3) bleeding on probing was found with pocket depths ≥5 mm in half of the zygomatic implants; (4) prevalence of bone septa is higher in atrophic maxillae, and changes on nasopalatine canal can reduce up to 44.4% of the full length of buccal bone plates; (5) female patients have less medullar bone quantity and connectivity than male patients; (6) transectioning of nutrient vessels is easier and accelerates resorption; (7) stress does not concentrate on maxillary sinus base cortical bone contiguous to trabecular bone; (8) splinted implants receive nine times less load than nonsplinted implants even under oblique loading; (9) implant stability quotient (ISQ) values for implants ranged between 60 and 65; (10) in vivo force transfer to implants is similar between fixed prostheses and overdentures; (11) inclined implants generate better biomechanical responses; (12) masticatory efficiency and bite forces improve in maxillectomized patients who receive obturators with milled bar attachments. Conclusion: Sound implant‐supported choices for an atrophic maxilla must be made with a thorough understanding of its anatomic and biomechanical factors.     

Critical Appraisal. Effects of bleaching on tooth structure and restorations, part I: effects on enamel

Tooth whitening has become a common treatment over the last 15 years, and much research has been reported on the effects of bleaching procedures on enamel, dentin, and restorative materials. We are presenting a series of Critical Appraisals on this topic, beginning this issue with a focus on the effects of bleaching on enamel.