Dental Materials

Currently, no consensus exists regarding the best adhesion protocol for zirconia used in dentistry; this is important particularly for restorations where mechanical retention is deficient. This systematic review analyzed the adhesion potential of resin-based and glass-ionomer luting cements to zirconia and aimed to highlight the possible dominant factors affecting the bond strength results to this substrate. Original scientific papers on adhesion to zirconia published in the MEDLINE (PubMed) database between 01/01/1995 and 01/06/2011 were included in this systematic review. The following MeSH terms, search terms, and their combinations were used: "Dental bonding", "Zirconium", "Zirconia", "Y-TZP", "Y-TZP ceramic", "Materials Testing/methods", "Test", "Cement", and "Resin bonding". Two reviewers performed screening and data abstraction. Descriptive statistics were performed and the frequencies o...

In case of severe dental erosion, the maxillary anterior teeth are often particularly affected. Restoring such teeth conventionally (ie, crowns) would frequently involve elective endodontic therapy and major additional loss of tooth structure. A novel, minimally invasive approach to restore eroded teeth has been developed and is currently being tested in the form of a prospective clinical trial, termed The Geneva Erosion Study. To avoid crowns, two separate veneers with different paths of insertion have been used to restore the affected anterior maxillary teeth, regardless of clinical crown length and amount of remaining enamel. This treatment is called The Sandwich Approach. The purpose of this case series study was to analyze the mid-term clinical outcome of maxillary anterior teeth affected by severe dental erosion that were restored following the Sandwich Approach. Twelve consecutively consulting patients (mean age: 39.4 years) suffering from advanced dental erosion have been en...

The restoration of anterior teeth is a difficult task, even for an experienced operator. Currently there are many different ceramic systems that can be used to achieve highly esthetic results. These include metal-ceramics with porcelain margins, Dicor, In-Ceram, Cerestore, Hi-Ceram, IPS-Empress, Cerapearl, Optec, and CAD/CAM ceramics. While metal-ceramics have been used for more than four decades, the quest for a material that transmits and refracts light like a natural tooth has inspired research into all-ceramic restorations. The purpose of this paper is to briefly discuss the properties of each of the above-mentioned materials and clinically evaluate the optical behavior of: (1) metal-ceramic crowns with castings 2 mm short of the shoulder preparation and 360-degree porcelain margins; (2) In-Ceram Spinell restorations; and (3) IPS Empress restorations, and to compare these with metal-ceramic crowns with copings to the shoulder preparation and 180-degree porcelain margins. Light t...

of the bur. Additional abrasion mesial and distal to the center line of the base can further reduce the force needed to fracture the bracket in debonding (C). Once the fracture line has been created, use either a Weingart or a How plier to squeeze and fracture the tie wings (D). How pliers tend to produce better results than Weingart pliers because of the greater distance between the plier hinge and tips, which makes for a better fit between the internal surfaces of the tips and the external surfaces of the tie wings. In most cases, the two halves of the bracket will debond simultaneously. If one half stays on the tooth, it is easily removed by applying a rocking motion with the same plier. Ceramic fragments often remain on the enamel after debonding of monocrystalline brackets1 (E), requiring removal with the same high-speed diamond bur under water cooling. Any adhesive remnants should be removed by using a low-speed, sixor 12-blade tungsten carbide bur with a smooth, rounded tip. ...

Replacement of lost teeth using oral implants is an accepted treatment modality with well-documented high long-term success rates. Conventional screw- or threaded cylinder-type implants have been used almost exclusively. Their incongruence with the extraction socket necessitates the use of a barrier membrane or bone augmentation to prevent down-growth of connective tissue or epithelium between the implant and socket. Although some minor changes in implant design have been made, the neck and abutment connection areas have not changed much in the past 30 years. Custom-made root analog implants have been employed clinically in rare instances; however, they yielded failure rates of up to 96% at 1 year of follow-up. So far, ovoid implants are the closest in design regarding resemblance to the natural tooth anatomy. Root analog zirconia implants with macroretentions were developed and produced for immediate single-stage replacement of missing or hopeless teeth. This article discusses the ...

There is no consensus in the literature regarding the potential toxicity of universal dental adhesives (UDA). Being used in close proximity to the pulp, their biocompatibility should be an important factor in dental research. The aim of the present study was to evaluate the biocompatibility of UDA in an in vitro model. The study was performed using a monocyte/macrophage peripheral blood SC cell line (ATCC CRL-9855) on four specific UDA, namely: All-Bond Universal (Bisco); CLEARFIL Universal Bond Quick (Kuraray); G-Premio BOND (GC); Single Bond Universal (3M ESPE). The cytotoxicity of the investigated UDA was measured using the XTT colorimetric assay. The genotoxicity of the analyzed compounds was evaluated using an alkaline version of the comet assay. Furthermore, flow cytometry (FC) apoptosis detection was performed using the FITC Annexin V Apoptosis Detection Kit I. FC cell-cycle arrest assessment was performed using propidium iodide staining. The study observed significant differ...

To evaluate the effect of an 8% arginine-calcium carbonate fluoride-free desensitizing paste on the surface roughness of resin composite, porcelain, amalgam, gold, and human dental enamel both prior to and following simulated toothbrushing. A resin composite (Filtek Supreme), a commercial porcelain (IPS Empress), an amalgam (Dispersalloy), gold (JIF-PF) and human dental enamel were used, as well as commercial finishing and polishing instruments. Eight two-sided samples were fabricated for each group. The composite and amalgam samples were stored at 100% relative humidity and 37 degrees C for 48 hours prior to measuring the surface roughness and completing the subsequent finishing and polishing procedures. Enamel blocks were cut from human lesion-free teeth and embedded in acrylic. The blocks were then polished flat with high polishing pastes. For gold and porcelain, the same size was used and the materials processed by a professional dental laboratory. Following storage, each surfac...

To evaluate in vivo collagen fiber behavior around two different dental implant necks placed in the mandibular bone of adult pigs. Scanning electron microscopic (SEM) and profilometric analyses were performed on both types of implant necks to evaluate the different surface morphology. Ten dental implants with machined titanium necks and 20 implants with zirconia necks were inserted into the mandibles of five adult pigs. Three months later, the animals were sacrificed; samples from the peri-implant mucosa were obtained and prepared for histologic analysis. Evaluation of collagen fiber orientation in the connective tissue surrounding the implant necks was performed by polarized light microscopy. Inflammation in the peri-implant soft tissues was also measured via the Gingival Index. Postoperative healing was uneventful; all implants, except for one of each type, were osseointegrated after 3 months. SEM and profilometric analyses confirmed that zirconia necks showed Ra, Rq, and Rz value...

This study investigated the fracture resistance of maxillary acrylic resin complete dentures subjected to long-term water immersion. Maxillary acrylic resin complete dentures were fabricated from five denture base resins. Half of the dentures were stored in water for 50 h, and the other half were kept in water for 180 days before testing. Ten specimens were fabricated per group. The flexural load at the proportional limit (FL-PL) of the dentures was tested. A two-way anova revealed a significant difference in FL-PL because of the denture base material variable. There were no significant differences in FL-PL because of the effect of water immersion and the interaction between the effect of water immersion and the denture base material. The FL-PLs of the dentures fabricated with the two conventional heat-processed resins, the pour-type autopolymerizing resin and the microwave energy-processed resin were not significantly different from each other; they were significantly higher than the light-activated resin in regard to their FL-PL. The FL-PLs of the maxillary acrylic resin complete dentures did not change after long-tern water immersion, and the FL-PL of the denture fabricated from the light-activated resin was lower than those of the other materials.

INTRODUCTION: It is known that posterior composite restorations have high failure rates and high frequency of replacement as shown by studies. This may be attributed to the inability of conventional fillers to withstand the forces of mastication in the posterior region. New methods of reinforcement such as glass fibers are being used to increase the mechanical properties of dental composites. OBJECTIVES: was to compare the effect of aging in distilled water at 37°C for 1 day, 3 months and 6 months on the flexural strength and fracture toughness of a fiber reinforced composite (EverX posterior, GC, Europe), a nano-hybrid ceramic filled composite (IPS Empress Direct, Ivoclar Vivadent, Lieschtenstein) and a nano-hybrid zirconia filled composite (Z250 XT, 3M ESPE, USA). MATERIALS AND METHODS: For each test, twenty-one specimens were fabricated from each of the three composites and were then subdivided into three subgroups of seven specimens each according to the aging period in distilled water. After each aging period, the specimens were fractured in a Universal testing machine and the results were analyzed using ANOVA and post hoc test (Fisher's LSD) at p<0.05 significance level. Following each test, the fractured surfaces of the 6 months aged specimens were examined using SEM. RESULTS: The flexural strength and fracture toughness of the fiber-reinforced composite was the highest with a statistical significance in the three aging periods followed by the nano-hybrid zirconia filled composite and the least was the nano-hybrid ceramic filled composite.SEM imaging findings were consistent with the results. CONCLUSIONS: The fiber-reinforced composite had the highest flexural strength and fracture toughness after each of the three aging periods Although aging in water decreased the mechanical properties of the fiber-reinforced composite, it still remained higher than the two nano-hybrid composites which ensures its ability to withstand forces of mastication in the posterior region.

ABSTRACT : The root canal system is an arborizational, anastomotic, byzanthine, labyrinthine complexity, morphologically comparable to a mosaic. While primary canals exist, the tributaries, accessory branches and lumina of dentinal tubules harbour extensive tissue and microflora which if left untreated remains vector for persistent and refractory pathology. Therefore root canal  shaping and cleaning is of utmost importance in the success of root canal treatment. Number of systems are available for effective shaping accounting from hand files to nickel titanium rotary files to the new single file concept “WAVE ONE” KEYWORDS : Wave One, Reciprocating Motion, Nickel Titanium, Reverse  Balanced Force Technique, vCJD
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Glass polyalkenoate cements (GPCs) have been used in dentistry for over 40 years. These novel bioactive materials are the result of a reaction between a finely ground glass (base) and a polymer (acid), usually poly(acrylic acid) (PAA), in the presence of water. This article reviews the types of PAA used as reagents (including how they vary by molar mass, molecular weight, concentration, polydispersity and content) and the way that they control the properties of the conventional GPCs (CGPCs) formulated from them. The article also considers the effect of PAA on the clinical performance of CGPCs, including biocompatibility, rheological and mechanical properties, adhesion, ion release, acid erosion and clinical durability. The review has critically evaluated the literature and clarified the role that the polyacid component of CGPCs plays in setting and maturation. This review will lead to an improved understanding of the chemistry and properties of the PAA phase which will lead to further innovation in the glass-based cements field.

Dental school graduates have many options following graduation. Many are pursuing additional education and training by doing a residency program. As more graduates consider this career path, these programs have become more competitive. This study evaluates the competitiveness of match programs in dental residency programs by assessing data over a 9-year period for programs in the National Matching Service. The number of applicants participating in the match, number of positions offered, number of positions filled, and number of positions unfilled were analyzed for General Practice Residency (GPR), Advanced Education in General Dentistry (AEGD), Oral Maxillofacial Surgery (OMS), Pediatric Dentistry (PED), Orthodontics (ORTHO) and Dental Anesthesiology (ANES). The result has been an overall increase in number of applicants for these programs. Based on positions offered, ORTHO, PED, and OMS are the most competitive programs. PED programs were the most competitive due to the increase in applicants and relatively unchanged available positions.