OBJECTIVES:(1) To assess whether there is evidence of an association between the number of peri-implant tissue complications and patient characteristics such as gender, diabetes status, smoking status, and bite force; (2) To assess whether there is evidence of an association between the number of peri-implant tissue complications and location of the implant, surgical technique used, bone graft status and sinus lift status.MATERIALS AND METHODS:This randomized, controlled clinical trial included a total of 176 implants (OsseoSpeed, DENTSPLY) in 67 participants with 88 fixed dental prostheses. Information was obtained from health histories, a baseline exam, surgical notes, and post-operative exams. The data were analyzed using Fisher's exact and Mann-Whitney tests and generalized estimating equations using logistic regression with a significance level set at 0.05.RESULTS:All 176 implants survived within a recall period of 3 years, but 11 implants demonstrated peri-implant tissue complications. Ten sites showed dehiscence and one case exhibited vertical bone loss. There was a statistically significant association between surgical technique used (1-stage or 2-stage) and the presence of soft tissue complications (P = 0.005), where 2-stage surgery was associated with a higher frequency of peri-implant soft tissue complications. A correlation, although not statistically significant (P = 0.077), was noted, between peri-implant tissue complications and bone grafting, suggesting a possible role for this factor as well.CONCLUSIONS:Participants who did not require any second-stage surgery at the implant sites experienced fewer complications. Therefore, additional surgical procedures should be performed judiciously considering their possible effects on peri-implant tissue health.CLINICAL SIGNIFICANCE:The clinical implication of this research study is that secondary surgery should be considered with caution during implant placement and it should be performed only when other options have been exhausted, as it has been shown to have a direct adverse effect on the long-term peri-implant tissue health.

Objective. This study was performed to evaluate the biocompatibility of nine types of pure metals using 36 experimental prosthetic titanium-based alloys containing 5, 10, 15, and 20 wt% of each substituted metal.Methods. The cell viabilities for pure metals on Ti alloys that contain these elements were compared with that of commercially pure (CP) Ti using the WST-1 test and agar overlay test.Results. The ranking of pure metal cytotoxicity from most potent to least potent was: Co > Cu > In > Ag > Cr > Sn > Au > Pd > Pt > CP Ti. The cell viability ratios for pure Co, Cu, In, and Ag were 13.9 +/- 4.6%, 21.7 +/- 10.4%, 24.1 +/- 1 5.7%, and 24.8 +/- 6.0%, respectively, which were significantly lower than that for the control group (p < 0.05). Pure Pd and Pt demonstrated good biocompatibility with cell viabilities of 93.8 +/- 9.6% and 97.2 +/- 7.1%, respectively. The Ti-5Pd alloy exhibited the highest cell viability (128.4 +/- 21.4%), which was greater than that of GP Ti. By alloying pure Co or Cu with Ti, the cell viabilities for the Ti-xCo and Ti-xCu alloys increased significantly up to 10 wt% of the alloying element followed by a gradual decrease with a further increase in the concentration of the alloying element. Based on the agar overlay test, pure Ag, Co, Cr, Cu, and In were ranked as 'moderately cytotoxic', whereas all Ti alloys were ranked as 'noncytotoxic'.Signcance. The cytotoxicity of pure Ag, Co, Cr, Cu, and In suggests a need for attention in alloy design. The cytotoxicity of alloying elements became more biocompatible when they were alloyed with titanium. However, the cytotoxicity of titanium alloys was observed when the concentration of the alloying element exceeded its respective allowable limit. The results obtained in this study can serve as a guide for the development of new Ti-based alloy systems. (C) 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

PURPOSE:Occlusal reduction is considered a fundamental step for providing adequate and uniform space for the ceramic prosthesis; however, a flat occlusal surface is usually found. The prosthesis design influences the resistance to deformation and the stress state within the ceramic. This finite element (FE) study analyzes the influence of changing the substructure design on the stress distribution of a metal-ceramic crown in a premolar tooth with three types of occlusal reduction.MATERIALS AND METHODS:Each part of three-dimensional metal ceramic complete crown models was designed according to the space provided by different levels of occlusal reduction and the same external morphology of the tooth. Three models were designed: (1) correct occlusal reduction with a uniform thickness of the substructure (0.3 mm) and the veneering porcelain (1.5 mm); (2) flat occlusal reduction with different thicknesses of veneering porcelain to produce a uniform substructure; and (3) a flat occlusal reduction with different thicknesses of substructure for a uniform thickness of veneering porcelain.RESULTS:Stress distributions were very similar in the three models. The highest tensile stresses were concentrated immediately below the midline fissure in both the veneering porcelain and the metal alloy substructure. Although models with flat occlusal reduction had lower stress values, this preparation results from a reduction that removes a greater amount of sound tissue, which may increase the probability of dental pulp injury.CONCLUSIONS:Occlusal reduction must be anatomic; however, when a flat occlusal reduction already exists, the substructure must reproduce the correct anatomic form to allow a uniform thickness of the veneering porcelain.

Objective: Fractures of posterior fixed dental all-ceramic prostheses can be caused by one or more factors including prosthesis design, flaw distribution, direction and magnitude of occlusal loading, nature of supporting infrastructure (tooth root/implant), and presence of adjacent teeth. This clinical study of implant-supported, all-ceramic fixed dental prostheses, determined the effects of (1) presence of a tooth distal to the most distal retainer; (2) prosthesis loading either along the non-load bearing or load bearing areas; (3) presence of excursive contacts or maximum intercuspation contacts in the prosthesis; and (4) magnitude of bite force on the occurrence of veneer ceramic fracture.Methods: 89 implant-supported FDPs were randomized as either a three-unit posterior metal-ceramic (Au-Pd-Ag alloy and InLine POM, Ivoclar, Vivadent) FDP or a ceramicceramic (ZirCAD and ZirPress, Ivoclar, Vivadent) FDP. Two implants (Osseospeed, Dentsply) and custom abutments (Atlantis, Dentsply) supported these FDPs, which were cemented with resin cement (RelyX Universal Cement). Baseline photographs were made with markings of teeth from maximum intercuspation (MI) and excursive function. Patients were recalled at 6 months and 1-3 years. Fractures were observed, their locations recorded, and images compared with baseline photographs of occlusal contacts.Conclusion: No significant relationship existed between the occurrence of fracture and: (1) the magnitude of bite force; (2) a tooth distal to the most distal retainer; and (3) contacts in load-bearing or non-load-bearing areas. However, there was a significantly higher likelihood of fracture in areas with MI contacts only.Clinical significance: Because of the absence of a periodontal ligament, this clinical study demonstrates that there is a need to evaluate occlusion differently with implant-supported prostheses than with natural tooth supported prostheses. Implant supported prostheses should have minimal occlusion and lighter contacts than those supported by natural dentition. (C)2014 Elsevier Ltd. All rights reserved.

Recent reports on bilayer ceramic crown prostheses suggest that fractures of the veneering ceramic represent the most common reason for prosthesis failure.Objective. The aims of this study were to test the hypotheses that: (1) an increase in core ceramic/veneer ceramic thickness ratio for a crown thickness of 1.6 mm reduces the time-dependent fracture probability (Pf) of bilayer crowns with a lithium- disilicate-based glass-ceramic core, and (2) oblique loading, within the central fossa, increases Pf for 1.6mm-thick crowns compared with vertical loading.Materials and methods. Time-dependent fracture probabilities were calculated for 1.6-mmthick, veneered lithium- disilicate-based glass-ceramic molar crowns as a function of core/veneer thickness ratio and load orientation in the central fossa area. Time-dependent fracture probability analyses were computed by CARES/Life software and finite element analysis, using dynamic fatigue strength data for monolithic discs of a lithium-disilicate glass-ceramic core (Empress 2), and ceramic veneer (Empress 2 Veneer Ceramic).Results. Predicted fracture probabilities (Pf) for centrally loaded 1.6-mm-thick bilayer crowns over periods of 1, 5, and 10 years are 1.2%, 2.7%, and 3.5%, respectively, for a core/veneer thickness ratio of 1.0 (0.8 mm/0.8 mm), and 2.5%, 5.1%, and 7.0%, respectively, for a core/veneer thickness ratio of 0.33 (0.4 mm/1.2 mm).Conclusion. CARES/Life results support the proposed crown design and load orientation hypotheses.Signcance. The application of dynamic fatigue data, finite element stress analysis, and CARES/Life analysis represent an optimal approach to optimize fixed dental prosthesis designs produced from dental ceramics and to predict time-dependent fracture probabilities of ceramic-based fixed dental prostheses that can minimize the risk for clinical failures. (C) 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

PURPOSE:Analyzing the clinical performance of restorative materials is important, as there is an expectation that these materials and procedures will restore teeth and do no harm. The objective of this research study was to characterize the clinical performance of metal-ceramic crowns, core ceramic crowns, and core ceramic/veneer ceramic crowns based on 11 clinical criteria.MATERIALS AND METHODS:An IRB-approved, randomized, controlled clinical trial was conducted as a single-blind pilot study. The following three types of full crowns were fabricated: (1) metal-ceramic crown (MC) made from a Pd-Au-Ag-Sn-In alloy (Argedent 62) and a glass-ceramic veneer (IPS d.SIGN veneer); (2) non-veneered (glazed) lithium disilicate glass-ceramic crown (LDC) (IPS e.max Press core and e.max Ceram Glaze); and (3) veneered lithia disilicate glass-ceramic crown (LDC/V) with glass-ceramic veneer (IPS Empress 2 core and IPS Eris). Single-unit crowns were randomly assigned. Patients were recalled for each of 3 years and were evaluated by two calibrated clinicians. Thirty-six crowns were placed in 31 patients. A total of 12 crowns of each of the three crown types were studied. Eleven criteria were evaluated: tissue health, marginal integrity, secondary caries, proximal contact, anatomic contour, occlusion, surface texture, cracks/chips (fractures), color match, tooth sensitivity, and wear (of crowns and opposing enamel). Numerical rankings ranged from 1 to 4, with 4 being excellent, and 1 indicating a need for immediate replacement. Statistical analysis of the numerical rankings was performed using a Fisher's exact test.RESULTS:There was no statistically significant difference between performance of the core ceramic crowns and the two veneered crowns at year 1 and year 2 (p > 0.05). All crowns were rated either as excellent or good for each of the clinical criteria; however, between years 2 and 3, gradual roughening of the occlusal surface occurred in some of the ceramic-ceramic crowns, possibly caused by dissolution and wear of the glaze. Statistically significant differences in surface texture (p= 0.0013) and crown wear (p= 0.0078) were found at year 3 between the metal-ceramic crowns and the lithium-disilicate-based crowns.CONCLUSION:Based on the 11 criteria, the clinical performance of ceramic-ceramic crowns was comparable to that of the metal-ceramic crowns after 2 years; however, gradual roughening occurred between years 2 and 3, which resulted in differences in surface texture and wear.

We tested the hypotheses that glass-ceramic veneers and overglazes degrade by ion exchange in an acidic environment, and that they degrade by breakdown of the silica network in a basic environment. Disk specimens of glass-ceramic veneer and glaze were fabricated and immersed in pH 2, 7, or 10 buffer solutions, for 1, 3, 5, 10, 15, and 30 days. Each specimen was placed in a shaker bath containing de-ionized distilled water at 80°C. Concentrations of Al(3+), Ca(2+), Zn(2+), Li(2+), and Si(4+) were analyzed by means of inductively coupled plasma atomic emission spectrometry (ICP/AES). Statistical analyses were performed by factorial ANOVA. Significant differences occurred among leached ion concentrations as a function of material type, solution pH, and exposure time. A substantial release of Si occurred at pH 10 over time, leading to a breakdown of the glass phase. At pH 2, dissolution was controlled by an ionic exchange mechanism. We conclude that ceramic veneers and glazes may be susceptible to considerable degradation in low- and high-pH buffer solutions.

Zirconia-based dental prostheses undergo various grinding steps and heat treatments in preparation for dental patient use. Post-sintered grinding induces a tetragonal-to-monoclinic phase transformation that may lead to failure. These grinding conditions were simulated on fully sintered yttria-stabilized zirconia (Ivoclar IPS e.max ZirCAD, Ivoclar Vivadent, Schaan, Liechtenstein) using two applied loads (10 and 40 N) and different sizes of diamond grinding media (15-, 45-, and 70-μm particles). X-ray diffraction (XRD) and Raman spectroscopy were shown to be inadequate to analyze the monoclinic phase within the surface. Grazing incidence XRD correctly identified the presence of monoclinic phase on the ground zirconia surfaces. However, we conclude that, given the resulting ground microstructure, this technique only provides a qualitative measure for the depth profiles of the monoclinic phase for different grinding conditions. It was shown that regeneration of zirconia converts all monoclinic phase to the tetragonal phase, including conversion in specimens that were subjected to the harshest grinding conditions.

PURPOSEThe aim of this study was to determine the survival rates over time of implant-supported ceramic-ceramic and metal-ceramic prostheses as a function of core-veneer thickness ratio, gingival connector embrasure design, and connector height.MATERIALS AND METHODSAn IRB-approved, randomized, controlled clinical trial was conducted as a single-blind pilot study involving 55 patients missing three teeth in either one or two posterior areas. These patients (34 women; 21 men; age range 52-75 years) were recruited for the study to receive a three-unit implant-supported fixed dental prosthesis (FDP). Two implants were placed for each of the 72 FDPs in the study. The implants (Osseospeed, Astra Tech), which were made of titanium, were grit blasted. A gold-shaded, custom-milled titanium abutment (Atlantis, Astra Tech), was secured to each implant body. Each of the 72 FDPs in 55 patients were randomly assigned based on one of the following options: (1) A.MATERIALceramic-ceramic (Yttria-stabilized zirconia core, pressable fluorapatite glass-ceramic, IPS e.max ZirCAD, and ZirPress, Ivoclar Vivadent) B. metal-ceramic (palladium-based noble alloy, Capricorn, Ivoclar Vivadent, with press-on leucite-reinforced glass-ceramic veneer, IPS InLine POM, Ivoclar Vivadent); (2) occlusal veneer thickness (0.5, 1.0, and 1.5 mm); (3) curvature of gingival embrasure (0.25, 0.5, and 0.75 mm diameter); and (4) connector height (3, 4, and 5 mm). FDPs were fabricated and cemented with dual-cure resin cement (RelyX, Universal Cement, 3M ESPE). Patients were recalled at 6 months, 1 year, and 2 years. FDPs were examined for cracks, fracture, and general surface quality.RESULTSRecall exams of 72 prostheses revealed 10 chipping fractures. No fractures occurred within the connector or embrasure areas. Two-sided Fisher's exact tests showed no significant correlation between fractures and type of material system (p = 0.51), veneer thickness (p = 0.75), radius of curvature of gingival embrasure (p = 0.68), and connector height (p = 0.91).CONCLUSIONSAlthough there were no significant associations between connector height, curvature of gingival embrasure, core/veneer thickness ratio, and material system and the survival probability of implant-supported FDPs with zirconia as a core material, the small number of fractures precludes a definitive conclusion on the dominant controlling factor.

Objective: This study was performed to evaluate the biocompatibility of nine types of pure metal ingots (Ag, Al, Cr, Cu, Mn, Mo, Nb, V, Zr) and 36 experimental titanium (Ti) alloys containing 5, 10, 15, and 20 wt% of each alloying element.Methods: The cell viabilities for each test group were compared with that of CP-Ti using the WST-1 test and agar overlay test.Results: The ranking of pure metal cytotoxicity from most potent to least potent was as follows: Cu > Al > Ag > V > Mn > Cr > Zr > Nb > Mo > CP-Ti. The mean cell viabilities for pure Cu, Al, Ag, V, and Mn were 21.6%, 25.3%, 31.7%, 31.7%, and 32.7%, respectively, which were significantly lower than that for the control group (p < 0.05). The mean cell viabilities for pure Zr and Cr were 74.1% and 60.6%, respectively (p < 0.05). Pure Mo and Nb demonstrated good biocompatibility with mean cell viabilities of 93.3% and 93.0%, respectively. The mean cell viabilities for all the Ti-based alloy groups were higher than 80% except for Ti-20Nb (79.6%) and Ti-10V (66.9%). The Ti-10Nb alloy exhibited the highest cell viability (124.8%), which was higher than that of CP-Ti. Based on agar overlay test, pure Ag, Cr, Cu, Mn, and V were ranked as 'moderately cytotoxic', whereas the rest of the tested pure metals and all Ti alloys, except Ti-10V (mild cytotoxicity), were ranked as 'noncytotoxic'.Significance: The results obtained in this study can serve as a guide for the development of new Ti-based alloy implant systems. (C) 2013 Elsevier LtdElsevier B. V. All rights reserved.

The aim of this study was to evaluate the bond strength of three adhesive systems: Excite™, Adper Prompt L-Pop™ and AdheSE One™ to varying degrees of fluorotic enamel using micro-tensile bond strength (μTBS) tests. Human enamel was classified according to the Thylstrup and Fejerskov Index. The interface resin-enamel was observed using stereoscopic and electron microscopy. The Excite™, achieved the highest μTBS when bonded to healthy enamel and decreased as the degree of fluorosis increased (p<0.05). The Prompt L-Pop™ improved the bonding on moderate and severe fluorosis. The μTBS of the AdheSE One™, was significantly lower in all degrees of fluorotic enamel (p<0.05) indicating a very poor bonding ability to enamel. These results will provide clinicians with preliminary data to assist them in the selection of the most effective adhesive systems for treatment of fluorosis enamel, resulting in more successful restorative care.

"Nothing worthwhile is ever without complications."Nora RobertsThe recent increase in reports from clinical studies of ceramic chipping has raised the question of which criteria should constitute success or failure of total-ceramic prostheses. Terminologies such as minor chipping [1], partial chipping, technical complications [2,3], and biological complications have crept into the dental terminology and they have complicated our classification of success and failure of these crown and bridge restorations. Some journals have permitted the reporting of fractures as "complications" and they are not necessarily classified as failures in the study. One study has attempted to classify chipping fractures according to their severity and subsequent treatment [4]. This is a promising approach to resolve the challenges to the classification of chipping fracture.The term 'chipping fracture' is more descriptive than 'chipping' since the latter term tends to imply an event of minor consequence. Two types of statistics are reported routinely in these studies, i.e., percent success, which is a measure of restorations that survive without any adverse effects, and percent survival, which is a measure of all restorations that survive even though they may have exhibited chipping fracture or they may have been repaired. Why has this scenario occurred? One possible explanation is that many of these types of fractures are very small and do not affect function or esthetics. Another reason is that corporate sponsors prefer to use the term chipping since it does not connote failure in the sense that the term fracture does. In any event, we need to be more precise in our scientific observations of fracture and classifications of the various types of fracture including details on the location of fracture and the prosthesis design configuration. Because of the lack of standardized methods for describing chipping fractures, materials scientists are unable to properly analyze the effect of material properties and design factors on the time-dependent survival probability of ceramic fixed dental prostheses (FDPs). Based on the review of clinical trials and systematic reviews of these trials, the present study was designed to develop guidelines for classifying the functional performance, success, survival, and susceptibility to chipping fracture, and subsequent treatment of ceramic and metal-ceramic restorations. Objective. To develop comprehensive descriptive guidelines and a clinical reporting form to assist dental scientists in their analyses of chipping fracture behavior of metal-ceramic and all-ceramic prostheses with particular emphasis on veneered-zirconia restorations. These guidelines are required to optimize the recording of fracture features that can be used to differentiate ceramic chipping fracture from bulk fracture and to assist dentists in identifying subsequent treatment that may minimize the need to replace affected restorations.A recording form for clinical fracture observations must be sufficiently clear and complete so that dental health professionals can translate the most relevant information in a context that allows their patients to fully understand the potential risks and benefits of treatment with ceramic restorations. It should clearly allow a clinician to determine whether or not a ceramic fracture constitutes a failure, which requires replacement of the prosthesis, or whether the fracture surface is relatively small or located in a nonfunctional area, i.e., one that is not contribute to occlusion, esthetics, proximal contacts, or food impaction.To accomplish this task, a review of the relevant publications of clinical trials was necessary to identify the variability in reporting of fracture events. The reviews were focused on clinical research studies of zirconia-based FDPs and PFM FDPs, which had been monitored through recall exams for three years or more. These reports and systematic reviews of all relevant publications were published in English dental journals between 2004 and 2010. The primary focus in this review was on the susceptibility to chipping fracture or bulk fracture of veneered zirconia-based fixed dental prostheses ( FDPs) and metal-ceramic FDPs, which are also referred to in this paper as porcelain-fused-to-metal ( PFM) FDPs. (C) 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Objectives. Test the hypotheses that there are equivalent wear rates for enamel-versus-enamel and ceramic-versus-enamel, analyzing the in vivo wear of crown ceramics, their natural enamel antagonists, and the corresponding two contralateral teeth; and, that bite force does not correlate with the wear.Methods. A controlled, clinical trial was conducted involving patients needing full coverage crowns opposing enamel antagonists. Bite forces were measured using a bilateral gnathodynamometer. Single-unit restorations of metal/ceramic (Argedent 62, Argen Corp/IPS d.SIGN veneer); or, core-ceramic/veneer from either, Empress2/Eris, or e.max Press core/e.max Ceram glaze (ceramics: Ivoclar Vivadent, USA) were randomly assigned, fabricated and cemented. Impressions were made of the ceramic crowns, as well as each maxillary and mandibular quadrant at one week (baseline) and one, two and three years. Resulting models were scanned (3D laser scanner). Maximum wear was calculated by superimposing baseline with annual images.Results. There were a total of thirty-six crowns required for thirty-one patients. Each restoration had three associated enamel teeth: crown, (1) antagonist, (2) contralateral and (3) contralateral-antagonist. SAS PROC MIXED (alpha = 0.05) indicated no statistical significance for mean maximum wear among crown ceramics, enamel antagonists and contralaterals. However, enamel wear was statistically significant in relation to intraoral location (p = 0.04) and among years (p < 0.02). Analyzed alone, the enamel contralateral-antagonist exhibited significantly greater wear (p < 0.001). Considering all wear sites, there was no correlation with bite force (p = 0.15).Significance. The ceramics and their antagonists exhibited in vivo wear rates within the range of normal enamel. Future studies should examine the wear implications of the contralateral-antagonist enamel. (c) 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

The aim of this study was to analyze the molecular structure of enamel with fluorosis using micro-Raman spectroscopy and compare it with that of healthy enamel. Eighty extracted human molars were classified into four fluorosis groups according to the Thylstrup-Fejerskov Index (TFI) [TFI: 0, Healthy enamel; 1-3, mild; 4-5, moderate; 6-9, severe fluorosis]. All samples were analyzed by micro-Raman spectroscopy. The integral areas of ν(1) (960 cm(-1)) phosphate peak as well as B-type carbonate peak (1070 cm(-1)) were obtained to analyze structural differences among the specimens. Although the differences were not statistically significant (P > 0.05), the mean of integral areas of ν(1) phosphate peak among groups indicated greater mineralization in the severe fluorosis group. However, there were statistically significant differences in the intensities, and the integral areas of B-type carbonate peak among groups (P < 0.05). Therefore, mineralization of the carbonate peak at 1070 cm(-1) decreased significantly in fluorotic groups, suggesting that carbonate ions are easily dissolved in the presence of fluoride. Although structurally fluorotic teeth are not more susceptible to dental caries, serious alteration in its surface topography may cause retention of bacterial plaque and formation of enamel caries. Micro-Raman spectroscopy is a useful tool for analyzing the molecular structure of healthy and fluorotic human enamel.

The aim was to characterize by atomic force microscopy (AFM) the nanostructure of human dentin surfaces affected by dental fluorosis (DF) before and after phosphoric acid etching. This study included 240 human dentin samples classified according to the severity of DF, which were divided into four groups using the Thylstrup-Fejerskov Index (TFI). Samples were analyzed by AFM before and after acid etching for 15, 30, and 60 s. The roughness (R(a)) for healthy dentin, and dentin with mild, moderate, and severe fluorosis were 440 nm, 442 nm, 445 nm, and 449 nm, respectively. After 15, 30, and 60 s of acid etching, all healthy and fluorotic dentin samples increased in roughness (p<0.05). The diameter of dentinal tubule orifices (D(t)) in healthy human dentin increased after acid etching for 60 s. We conclude that effective etching times are 15 s for healthy and mild dentin fluorosis, 30-s for moderately fluorosed dentin, and 45-60 s for severe fluorotic dentin.